Interventional radiology. Metal mesh prostheses in the treatment of strictures. Interventional surgery - X-ray endovascular surgery
At the intersection of radiology and surgery, a new clinical area has emerged - interventional radiology. Its essence is a combination of diagnostic X-ray and therapeutic measures in one procedure. First, the nature and extent of lesions are determined using x-ray studies, and then the necessary medical manipulations are performed. These procedures are performed by an X-ray surgeon in an X-ray room equipped for surgical interventions and angiographic studies. Medical procedures, as a rule, are implemented percutaneously with the help of special instruments (needles, catheters, conductors, stylets, etc.). The most widely used X-ray endovascular interventions. In oncological practice, X-ray endovascular occlusion (transcatheter occlusion of a vessel) is used, for example, to stop pulmonary, gastric, and intestinal bleeding. It is also used in some surgical interventions (for tumors of the kidney this method facilitates removal of the neoplasm). The X-ray endovascular method has become widespread for the selective administration of radioactive medical preparations, with tumor chemotherapy, since local effects of drugs are often more effective than intramuscular or intravenous.
Extravasal (extravascular) manipulations are also carried out. Under the control of X-ray television, bronchial catheterization is performed to obtain biopsy material. Under X-ray control, in particular CT, percutaneous transthoracic punctures of intrapulmonary or mediastinal formations are performed. Held aspiration biopsy to establish the nature of intrathoracic and abdominal formations, infiltrates, which saves patients from trial thoracotomy or laparotomy. It is also carried out to identify non-palpable formations in the mammary gland. Punctures are performed using X-ray television transmission, including CT, or using ultrasound. Can be used for targeted biopsy various methods radiodiagnosis. Each method has its own advantages and limitations. The choice of biopsy technique depends on the individual case and indications. For example, the cross section obtained with CT makes it possible to accurately localize anatomical structures and neoplasms, which makes it possible to use CT for organ puncture. Most often, CT is used in the following cases: biopsy of formations, the visualization of which is difficult with other research methods; formations with a diameter of less than 3 cm, deeply located formations or located close to the vessels, intestine, bones; drainage of abdominal abscesses; repeat biopsy for unsuccessful attempts using other methods.
From all of the above, it follows that the application beam methods research individual bodies and systems should be used in a targeted manner, taking into account the clinical objectives and the nature of the disease.
Interventional radiology is a branch of medical radiology that develops the scientific foundations and clinical application therapeutic and diagnostic manipulations carried out under the control of radiological examination.
Interventions consist of two stages. The first stage includes a radiation study (X-ray television transillumination, computed tomography, ultrasound or radionuclide scanning, etc.), aimed at establishing the nature and extent of the lesion. At the second stage, usually without interrupting the study, the doctor performs the necessary therapeutic manipulations (catheterization, puncture, prosthetics, etc.), which are often not inferior in efficiency, and sometimes even superior to surgical interventions, and at the same time have a number of advantages compared to them. They are more gentle, in most cases do not require general anesthesia; the duration and cost of treatment are significantly reduced; morbidity and mortality are reduced. Interventional interventions can be the initial stage in the preparation of severely weakened patients for the operation required in the subsequent operation.
Indications for interventional interventions are very wide, which is associated with a variety of tasks that can be solved using the methods of interventional radiology. Common contraindications are serious condition sick, acute infectious diseases, mental disorders, decompensation of the functions of the cardiovascular system, liver, kidneys, when using iodine-containing radiopaque substances - hypersensitivity to iodine preparations.
Preparation of the patient begins with explaining to him the purpose and methodology of the procedure. Depending on the type of intervention, different forms of premedication and anesthesia are used. All interventional interventions can be conditionally divided into two groups: X-ray endovascular and extravasal.
X-ray endovascular interventions, which have received the greatest recognition, are intravascular diagnostic and therapeutic manipulations carried out under X-ray control. Their main types are X-ray endovascular dilation, or angioplasty, X-ray endovascular prosthetics and X-ray endovascular occlusion.
vascular interventions.
1. Arterial angioplasty in peripheral and central vascular pathology.
This range of interventions includes balloon dilatation of arteries, vascular stenting, atherectomy. At obliterating diseases lower extremities, often, there is a need to restore the lumen of the affected vessels in order to eliminate ischemia. For this purpose, in 1964, Dotter and Judkins began to use a set of coaxial catheters for bougienage of the lumen of the arteries. But the greatest progress was made after the introduction of a special balloon catheter in 1976 by Gruntzig. Inflating the balloon, installed in the place of narrowing of the vessel, leads to the restoration of its lumen either in full or in sizes that allow to provide adequate nutrition limbs. In addition, there is the possibility of multiple dilations. In subsequent years, balloon dilations began to be used on brachiocephalic, coronary, renal, mesenteric arteries, hemodialysis fistulas. However, the inevitable traumatization of the intima, its subsequent hyperplasia, gives a high percentage of restenoses. In this regard, intravascular metal or nitinol prostheses - stents - have been developed. There are several modifications of stents, which can be divided into self-expanding and balloon expandable. Accordingly, the method of their implantation also differs. Wallstent placement is preceded by balloon dilatation, and with balloon expandable stents, this occurs simultaneously. Moreover, the use of polyethylene-coated stents allows them to be used for the treatment of aortic aneurysms and large arteries(including fusiform and large aneurysms) by creating a new vessel lumen. AT last years stenting of the vena cava with their compression by tumors, as well as any hollow tubular structures, such as the esophagus, pylorus, biliary tract, intestines, trachea and bronchi, ureters, nasolacrimal canal, began to be used. The main indications for such procedures are malignant inoperable tumors. Despite the palliative nature, dysphagia, esophageal-respiratory fistulas, mechanical jaundice, intestinal obstruction, urostasis.
2. The fight against pathological thrombosis.
Currently, regional thrombolysis has become widely used. The closest possible installation of the catheter to the thrombus allows to increase the efficiency and reduce the doses of fibrinolytic drugs administered through it, thereby reducing side effects such treatment. Some companies have developed systems for intravascular mechanical thrombus retraction and suction of fresh clots.
The most effective method of combating pulmonary embolism is the installation of metal filters in the inferior vena cava. This creates an obstacle in the way of large migrating blood clots. To install the filter, either transfemoral or transjugular access is used, a special system for installing and delivering the filter. Filters differ in their modification. The best known are the Gunther-Tulip and Bird's Nest filters from William Cook Europe, and the Greenfield filter from Medi-Tech/Boston Scientific.
3. Vascular embolizations.
This type of intervention is used to stop bleeding of various localization, treat a number of tumors, as well as for some aneurysms and vascular anomalies. Oily contrast agents, hemostatic gelatin sponge, Ivalon, sotradecol, 96% are used as embolizing agents. ethanol, metal coils, autohemoclots, microspheres with ferromagnets, etc. Hemostatic embolization is very effective in gastrointestinal bleeding, severe injuries pelvis, advanced bleeding tumors of the lung, kidney, bladder and female genitalia.
The method of chemoembolization of the hepatic artery is widely used in malignant primary and metastatic liver tumors. Here, the properties of oily contrast agents (lipiodol, etiodol, etiotrast, mayodil and iodolipol) have found application. When injected into the hepatic artery, they penetrate and deposit much more actively in the tumor tissue than in the hepatic parenchyma. Mixed with cytostatics (most often with doxorubicin), they have not only an ischemic, but also a chemotherapeutic effect. Some authors consider hepatic artery chemoembolization an alternative to liver resection for solitary tumor lesions, and for multiple liver metastases, although palliative, but the only way prolong the life of the patient and its quality.
Among other pathologies in which embolization is effective, it should be noted arteriovenous malformations, aneurysms of cerebral vessels with a clearly defined neck, some tumors of the musculoskeletal system, and open ductus arteriosus.
At the intersection of radiology and surgery, a new clinical area has emerged - interventional radiology. Its essence is a combination of diagnostic X-ray and therapeutic measures in one procedure. First, the nature and extent of the lesions are determined using x-ray studies, and then the necessary medical manipulations are performed. These procedures are performed by an X-ray surgeon in an X-ray room equipped for surgical interventions and angiographic studies. Medical procedures, as a rule, are carried out percutaneously with the help of special instruments (needles, catheters, conductors, stylets, etc.). The most widely used X-ray endovascular interventions. In oncological practice, X-ray endovascular occlusion (transcatheter occlusion of a vessel) is used, for example, to stop pulmonary, gastric, and intestinal bleeding. It is also used in some surgical interventions (for kidney tumors, this method facilitates the removal of the neoplasm). The X-ray endovascular method has become widespread for the selective administration of radioactive drugs, during tumor chemotherapy, since the local effect of drugs is often more effective than intramuscular or intravenous.
Extravasal (extravascular) manipulations are also carried out. Under the control of X-ray television, bronchial catheterization is performed to obtain biopsy material. Under X-ray control, in particular CT, percutaneous transthoracic punctures of intrapulmonary or mediastinal formations are performed. An aspiration biopsy is performed to determine the nature of intrathoracic and abdominal formations, infiltrates, which saves patients from trial thoracotomy or laparotomy. It is also carried out to identify non-palpable formations in the mammary gland. Punctures are performed using X-ray television transillumination, including CT, or using ultrasound. For targeted biopsy, various methods of radiation diagnostics can be used. Each method has its own advantages and limitations. The choice of biopsy technique depends on the individual case and indications. For example, the cross section obtained with CT makes it possible to accurately localize anatomical structures and neoplasms, which makes it possible to use CT for organ puncture. Most often, CT is used in the following cases: biopsy of formations, the visualization of which is difficult with other research methods; formations with a diameter of less than 3 cm, deeply located formations or located close to the vessels, intestine, bones; drainage of abdominal abscesses; re-biopsy in case of unsuccessful attempts to use other methods.
From all of the above, it follows that the use of radiation methods for examining individual organs and systems should be used purposefully, taking into account clinical problems and the nature of the disease.
The owners of the patent RU 2580189:
The group of inventions relates to the field of medicine. A method for magnetic resonance imaging (MRI) of a moving part of a patient's body placed in the examination area of the MRI machine, said method comprising the steps of: a) collecting trace data from a microcoil attached to an interventional instrument inserted into the body part, b) affecting the body part with a sequence of pulses to obtain one or more MR signals from it, wherein the movement and/or rotation parameters describing the movement of the body part are derived from the tracked data, the pulse sequence parameters being corrected so as to compensate for movement in the image by means of shift or rotation when scanning in accordance with the parameters of movement and / or rotation, while the MRI apparatus for implementing the method includes a main magnetic coil for generating a uniform constant magnetic field in the study area, a number of gradient coils for generating switchable magnetic field gradients in different in different directions in space in the study area, an RF coil for generating RF pulses in the study area and/or for receiving MR signals from the patient's body located in the study area, a control unit for controlling the time sequence of RF pulses and switchable magnetic field gradients, and a reconstruction unit. The information carrier contains computer-executable commands for implementing the MRI method of a moving part of the patient's body placed in the area of study of the MRI apparatus. The use of this group of inventions will reduce the scanning time and provide effective motion compensation. 3 n. and 8 z.p. f-ly, 2 ill.
FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES
The present invention relates to the field of magnetic resonance (MR) imaging. It relates to a method of MRI imaging of at least a moving part of a patient's body placed in an examination area of an MRI machine. The present invention also relates to an MRI machine and to a computer program for execution on an MRI machine.
BACKGROUND OF THE INVENTION
MR imaging techniques that use the interaction between magnetic fields and nuclear spins to form 2D or 3D images are now widely used, especially in the field of medical diagnostics, because for soft tissue imaging they are superior to other imaging techniques in many ways. relationships, do not require ionizing radiation and are generally non-invasive.
According to the MRI technique in general, the body of the patient to be examined is placed in a strong uniform magnetic field, the direction of which at the same time determines the axis (usually the z-axis) of the coordinate system on which the measurement is based. The magnetic field creates various energy levels individual nuclear spins depending on the strength of the magnetic field, which can be excited (spin resonance) by exposure to an electromagnetic alternating field (RF field) of a certain frequency (the so-called Larmor frequency, or MR frequency). From a macroscopic point of view, the distribution of individual nuclear spins forms an overall magnetization that can be brought out of equilibrium by the action of an electromagnetic pulse of the appropriate frequency (RF pulse), with the magnetic field located perpendicular to the z-axis, so that the magnetization comes into precessional motion around the z-axis . The precessional motion describes the surface of a cone whose aperture angle is called the deflection angle. The value of the deflection angle depends on the magnitude and duration of the applied electromagnetic pulse. In the case of the so-called 90° momentum, the spins deviate from the z-axis into the transverse plane (the deflection angle is 90°).
After the termination of the RF pulse, the magnetization returns to the initial state of equilibrium, in which the magnetization in the z direction increases again with one time constant T1 (spin-lattice or longitudinal relaxation time), and the magnetization in the direction perpendicular to the z axis is restored with another time constant T2 ( spin-spin or transverse relaxation time). The change in magnetization can be detected by RF receiving coils that are positioned and oriented within the examination area of the MRI machine such that the change in magnetization is measured in a direction perpendicular to the z-axis. The drop in transverse magnetization is accompanied, after application of, for example, a 90° pulse, by the transition of nuclear spins (caused by local inhomogeneities of the magnetic field) from an ordered state with the same phase to a state in which all phase angles are uniformly distributed (dephasing). The skew can be compensated for with a refocusing pulse (eg 180° pulse). This results in an echo (spin echo) in the receiving coils.
In order to create a spatial resolution in the body, linear gradients of the magnetic field in the direction of the three principal axes are imposed on a uniform magnetic field, which leads to a linear spatial dependence of the spin resonance frequency. The signal detected by the receiving coils in this case contains components of different frequencies that can be associated with different locations in the body. The signal data received by the receiving coils corresponds to the spatial frequency range and is referred to as k-space data. The k-space data typically includes a plurality of lines obtained with different phase encodings. Each row is digitized by collecting a number of samples. The k-space dataset is converted into an MR image, for example by means of a Fourier transform.
Cardiac interventional MR imaging is a promising tool in which precise localization of the interventional instrument can be combined with excellent soft tissue contrast. Moreover, functional information from the heart can be obtained through appropriate MRI techniques. The combination of MR imaging with tracking of interventional instruments is particularly attractive for therapeutic applications that require therapy monitoring, such as, for example, MR electrophysiological effects. However, cardiac MR imaging involves a trade-off between spatial resolution, scan time, and signal-to-noise ratio (SNR). Therefore, effective motion compensation is extremely important. Obtaining sufficient MR data for image reconstruction takes a finite period of time. The movement of the object being imaged, such as the rhythmic movement of the heart, in combination with respiratory movement patient, during a given finite acquisition time, typically results in motion artifacts on the corresponding reconstructed MR image. Acquisition time can only be reduced very slightly if a specific MR image resolution is set. On dynamic MR tomographic scans required for monitoring therapy, the movement of the examined object during data acquisition leads to various kinds blurring, mispositioning, and deformation artifacts. Prospective motion correction methods, such as the so-called navigator method or PACE, have been developed to overcome motion-related problems through prospective correction of tomography parameters, i.e. parameters of the pulse train used to receive the MR signal, which determine the location and orientation of the image field (FOV) within the imaging area. In the navigator method, an MR data set is obtained from a pencil-shaped area (navigator beam) that intersects the diaphragm of the patient being examined. This region is interactively positioned such that the position of the diaphragm can be reconstructed from the acquired MR data set and used for real-time FOV motion correction. The navigator method is primarily used to minimize the influence of respiratory movement in cardiac studies. In contrast to the navigator method, which requires a navigator beam to detect misalignments due to motion, the aforementioned PACE method uses pre-acquired dynamic images to prospectively correct tomography parameters in successive dynamic images. In addition, it is known to use ECG-based synchronization to synchronize imaging with the rhythmic movement of the heart, thereby reducing motion artifacts caused by the cardiac cycle.
Prior art motion compensation approaches suffer from the need to increase scan time due to the reduced scan duty cycle. In addition, the aforementioned navigator method requires complex scan planning.
On the other hand, it has recently been shown that MR imaging is able to visualize the effect of cardiac electrophysiological ablation shortly after ablation, and it has been demonstrated that ablation-related physiological changes can be identified by in situ MR imaging. However, there are currently limitations in image quality due to limited signal-to-noise ratio (SNR) and motion artifacts.
SUMMARY OF THE INVENTION
From the foregoing, it is easy to understand that there is a need for an improved method of interventional MR imaging. Therefore, it is an object of the present invention to enable controlled MRI therapy of moving body parts that does not require ECG synchronization, navigator techniques, or other time consuming or complex motion compensation methods.
In accordance with the present invention, a method for MR imaging of a moving part of a patient's body placed in the area of study of an MRI machine is described. This method includes the steps:
a) collecting traceable data from an interventional instrument inserted into the body part,
b) exposing said body part with a sequence of pulses to obtain one or more MR signals from it, wherein the movement and/or rotation parameters describing the movement of the body part (22) (10) are derived from the tracked data, and the pulse sequence parameters are corrected, so in order to compensate for the movement in accordance with the movement and/or rotation parameters, wherein the movement and/or rotation parameters describing the movement of the part (22) of the body (10) are derived from the tracked data, the pulse train parameters are corrected so as to compensate for the movement in accordance with the parameters movement and/or rotation,
c) obtaining the MP signal data set by repeating steps a) and b) several times,
d) reconstructing one or more MR images from the MR signal data set.
The method according to the present invention allows to obtain motion-compensated MR images at the location of an interventional instrument that has been inserted into a corresponding moving part (such as, for example, the heart) of the patient's body. The essence of the present invention is the use of tracked data, i.e. localization information collected from the interventional instrument to compensate for motion in the image. Said interventional tool preferably contains an active tracking means in order to report its location and orientation within the examined body part to the MRI machine used for imaging. Known active MR tracking techniques that use one or more RF microcoils attached to an interventional instrument are well suited to the method of the present invention. However, known passive markers that can be used in MR imaging in combination with suitable detection algorithms are also acceptable. Other non-MR based tracking methods can also be applied. In this case, a suitable interface is needed between the respective tracking system and the MRI machine in order to enable the use of tracked data in the management of sequences of the MRI machine.
Preferably, the tracked data collected in accordance with the present invention includes information regarding the instantaneous location (x, y, z coordinates) and/or orientation (Euler angles) of at least a portion of an interventional instrument (e.g., a catheter tip) within a region research. Where RF microcoils are attached to the interventional instrument, the corresponding RF microcoils are preferably connected to the MRI machine via a suitable transmission line (RF, optical or wireless). Suitable interfaces for incorporating such MR-based tracking into MR imaging techniques are known per se in the art (see, for example, US Pat. No. 2008/0097189 A1). Thus, the MRI machine includes a suitable software, which implements pulse sequences for receiving MR signals and collecting and estimating the coordinates of microcoils.
In the method according to the present invention, as mentioned above, the moving body part to be examined is subjected to a pulse train in order to obtain MR signals for image reconstruction, the pulse train parameters being corrected based on the monitored data. This means that the MRI machine adapts the scan parameters based on the tracked data, thereby causing the scan geometry to shift and/or rotate according to the moving anatomical structure being examined in real time. This adjustment of tomography parameters can be applied in accordance with the present invention even to individual rows of k-space. Correcting tomography parameters during acquisition of MR signals allows for prospective correction of random motion near the interventional instrument. The approach of the present invention is particularly useful for MRI-monitored therapies such as, for example, catheter ablation. The present invention utilizes the location information contained in the tracked data from an interventional instrument that remains in a fixed geometric location relative to the anatomical structure.
In accordance with a preferred embodiment of the present invention, dynamic MR image series are reconstructed from repeatedly acquired MR signal datasets. This means that a 4D MR scan is performed, with the pulse train parameters being continuously adjusted based on the collected tracking data, so that the FOV remains in a substantially time-constant geometric location with respect to the moving body part being examined.
If the intervention tool inadvertently "slips", i.e. moves relative to the anatomical structure being imaged and/or treated, there is an immediate enhancement of motion artifacts in MR images reconstructed in accordance with the present invention. These artifacts can be automatically detected and an appropriate alert can be generated for the user of the MRI machine and/or the interventionist.
Alternatively, the movement of the interventional tool relative to the moving body part can be detected in accordance with the present invention by detecting the deviation of the movement of the interventional tool from a repetitive movement pattern based on repeatedly collected tracking data. This method of detecting "slip" of the interventional tool can also be used to generate an alert to the interventionist.
The method according to the present invention thus preferably allows automatic detection of an incorrectly fixed position of a therapeutic or diagnostic interventional device in relation to the anatomical structure being treated and/or examined, while increasing the accuracy of the procedure. medical procedure and, consequently, the result of treatment. For this reason, the method of the present invention is particularly useful for interventional cardiac MR imaging using a trackable catheter-like device. Experienced specialist, performing the intervention, is able to firmly fix the interventional instrument in relation to the local cardiac anatomical structure, both in order to carry out treatment and to conduct any diagnosis. The tracked interventional instrument can then be immediately used to detect the local movement of the cardiac anatomical structure very accurately and with high temporal resolution. In accordance with the present invention, said tracking data allows for prospective motion correction in the image, i.e. by obtaining individual lines or segments of k-space, and thereby making it possible to obtain motion compensated MR signals without the need for navigation, ECG switching, or other methods of motion evaluation and/or compensation. Thus, faster MR imaging of the local anatomical structure becomes possible, which can be used to improve SNR while reducing motion artifacts. In the case of an actively tracked ablation catheter, the scan of the lesion can be efficiently performed without any geometric planning since the interventional instrument is located in close proximity to the lesion and therefore can be used directly to determine the FOV. This can be extremely useful for many point ablations, for example, to form a ring or a line of connected ablations, which is necessary for isolating the pulmonary veins. At the same time, the accuracy of the treatment procedure is greatly improved, since unintentional "sliding" of the instrument relative to the anatomical structure being treated is immediately and reliably recognized due to the principle of the present invention.
The method according to the present invention can be successfully combined with PROPELLER tomography. In the well-known PROPELLER concept (Periodic Rotation of Superimposed Parallel Lines with Improved Reconstruction), MP signals are collected in k-space into N bands, each of which consists of parallel lines corresponding to the lowest frequency L phase-coding lines in the k-space Cartesian sampling scheme. Each stripe, also referred to as a k-space vane, rotates 180°/N in k-space so that the complete MR data set approximately fills a circle in k-space. One of the essential features of the PROPELLER technology is that for each k-space blade, a central circular part of the k-space with a diameter L is obtained. central part can be used to reconstruct a low resolution image for each k-space vane. These low-resolution images or their k-spatial representations can be compared with each other in order to eliminate in-plane shifts and phase errors that are due to the movement of the object under study. In addition, a suitable method, such as cross-correlation, can be applied to determine which k-space vanes were obtained with a significant in-plane offset. Since the MR signals are combined in k-space prior to the reconstruction of the final MR image, the areas where the k-space vanes overlap preferably use MR data from the k-space vanes with the least amount of in-plane motion, so that artifacts caused by in-plane motion are decrease. The PROPELLER approach uses oversampling in the central part of k-space in order to obtain an MR imaging method that is robust to the movement of the body part being examined. The method according to the present invention can be used to correct the position and/or rotation of individual sequence k-space blades in the PROPELLER approach based on the collected tracking data. In this way, extremely accurate motion correction is achieved by combining the correlation of redundant data at the center of k-space with the collected tracked data from an interventional instrument that is fixed relative to the anatomical structure being examined.
The method according to the present invention described above can be carried out by means of an MRI apparatus including at least one main magnetic coil for generating a uniform constant magnetic field in the region of interest, a number of gradient coils for generating switchable magnetic field gradients in different directions in space in study area, at least one RF coil for generating RF pulses in the study area and for receiving MR signals from the patient's body located in the study area, a control unit for controlling the time sequence of RF pulses and switchable magnetic field gradients, a reconstruction unit and an imaging unit. To do possible fee tracked data from an interventional instrument according to the present invention, a suitable instrument tracking system must be connected to the MRI machine. For active MR-based tracking, at least one RF microcoil may be attached to the interventional instrument, with the tracked data collected by the MRI machine in the form of MR signals generated or detected by the RF microcoil.
The method according to the present invention can be successfully implemented on most of the MRI machines currently used in clinical practice. To this end, it is only necessary to use a computer program with which the MRI apparatus is controlled so that it performs the above-described steps of the method according to the present invention. Said computer program may be either on a storage medium or on a data network so that it can be downloaded for installation on the control unit of the MRI machine.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings disclose preferred embodiments of the present invention. It should be understood, however, that these drawings are for illustrative purposes only and not as a definition of the limits of the present invention. On the drawings
figure 1 shows the MRI apparatus for implementing the method according to the present invention;
figure 2 schematically shows the moving heart of a patient examined in accordance with the method according to the present invention.
DETAILED DESCRIPTION
Figure 1 shows the machine 1 MRI. This apparatus contains superconducting or resistive main magnetic coils 2 so that a substantially uniform time-constant main magnetic field is generated along the z-axis throughout the region of interest.
The magnetic resonance generation and control system applies a series of RF pulses and switchable magnetic field gradients to reverse or excite nuclear magnetic spins, induce magnetic resonance, refocus magnetic resonance, control magnetic resonance, encode magnetic resonance spatially or otherwise, saturate spins, and so on. similar, in order to conduct an MRI scan.
More specifically, the gradient pulse amplifier 3 applies current pulses to selected whole body gradient coils 4, 5 and 6 along the x, y and z axes of the region of interest. A digital RF emitter 7 transmits RF pulses or pulse packets through a receive/transmit switch 8 to a whole body RF bulk coil 9 to transmit RF pulses to the area of interest. A typical MR pulse train consists of a burst of short duration RF pulse segments which, together with each other and any applied magnetic field gradients, perform a selected nuclear magnetic resonance operation. The RF pulses are used to saturate, resonate, invert the magnetization, refocus the resonance, or manipulate the resonance and select the body part 10 placed in the region of interest. The MR signals are also detected by the RF volumetric coil 9 for the whole body.
To form MR images of limited areas of the body 10 using parallel imaging, a set of local array RF coils 11, 12, 13 is placed near the area selected for imaging. Matrix coils 11, 12, 13 can be used to receive MR signals induced by RF radiation from a whole body coil.
The resulting MR signals detected by the whole body RF surround coil 9 and/or the RF matrix coils 11, 12, 13 are demodulated by the receiver 14, preferably including a preamplifier (not shown). The receiver 14 is connected to the RF coils 9, 11, 12 and 13 via a receive/transmit switch 8.
The host computer 15 controls the gradient pulse amplifier 3 and the emitter 7 to generate any of a plurality of MR pulse sequences such as fast spin echo (TSE) imaging and the like. For the selected sequence, receiver 14 receives one or more lines of MR data in quick succession after each RF excitation pulse. The acquisition system 16 performs A/D conversion of the received signals and converts each line of MP data into a digital format suitable for further processing. AT modern devices The MRI acquisition system 16 is a separate computer that is specialized in acquiring raw image data.
Ultimately, the digital raw image data is reconstructed into an image representation by a reconstruction processor 17 that applies a Fourier transform or other suitable reconstruction algorithms such as SENSE or SMASH. The MR image may represent a flat section of the patient, an array of parallel flat slices, a three-dimensional volume, or the like. The image is then stored in image storage where it can be accessed to convert slices, projections, or other portions of the image representation into a suitable format for rendering, such as by a video monitor 18 that provides a human-readable display of the resulting MR image.
An interventional instrument 19, such as, for example, an ablation catheter, is inserted into the body 10 of the patient. The catheter 19 is connected to the receiving channel of the MRI machine 1 through the interface 21. The RF microcoil 20 is attached to the distal end of the catheter 19, which makes possible localization catheter tip by detecting MR signals with RF microcoil 20 in the presence of magnetic field gradients.
Figure 2 shows a schematic section of the patient's heart 22 at two different times, separated by a time interval Δt. The ablative catheter 19 is inserted into the heart 22, with the tip of the catheter, to which the microcoil 20 is attached, firmly fixed in the myocardium. Because the tip of the catheter 19 remains locally fixed with respect to the anatomical structure of the heart, the location information obtained from the tracked data collected by the microcoil 20 is used in accordance with the present invention to adjust the pulse train scan parameters in order to achieve real-time motion correction of the FOV 23 . Figure 2 shows that the position and orientation of the FOV 23 has changed over the time interval Δt. The actively tracked ablation catheter 19 is thus used to detect local movement of the anatomical structure in order to perform prospective correction of movement in the image. The FOV 23 moves and rotates so that it remains in a fixed geometric location with respect to the anatomical structure of the heart 22 under study. No navigator synchronization, ECG synchronization, or other motion compensation methods are required. The lesion created by the ablative catheter 19 can be directly scanned in high image quality, i. e. no motion artifacts caused by breathing and/or rhythmic motion of the heart 22. If the catheter 19 "slips" so that the catheter 19 moves in relation to the anatomical structure of the heart 22, motion artifacts immediately appear on the MR image reconstructed from the received MR signals. This occurs because the anatomical structure no longer remains in a fixed geometric location with respect to the FOV 23. A sharp increase in image artifacts can be used to generate an appropriate warning to the intervening specialist.
1. The method of magnetic resonance (MR) tomography of the moving part (22) of the body (10) of the patient, placed in the area of study of the apparatus (1) MRI, and this method contains the steps in which:
a) collect tracked data from at least one microcoil attached to the intervention tool (19) introduced into the part (22) of the body (10),
b) act on the part (22) of the body (10) with a sequence of pulses to obtain from it one or more MR signals, and the parameters of movement and / or rotation describing the movement of the part (22) of the body (10) are derived from the tracked data, and the parameters pulse sequences are corrected so as to compensate for movement in the image by shifting or rotating during scanning in accordance with the parameters of translation and / or rotation,
c) obtaining the MP signal data set by repeating steps a) and b) several times,
d) reconstructing one or more MR images from the MR signal data set.
2. The method of claim. 1, in which the tracked data includes information regarding the instantaneous position and/or orientation of at least part of the interventional tool (19) within the study area.
3. The method according to claim 1 or 2, wherein the movement of the interventional tool (19) relative to the part (22) of the body (10) is detected by detecting motion artifacts in the reconstructed MR image.
4. The method according to claim 3, wherein the pulse train parameters are corrected in step b) so that the image field (23) (FOV) remains in a substantially constant time geometric location with respect to the moving body part (22) ( ten).
5. The method of claim 1, wherein the dynamic series of MR images are reconstructed from repeatedly acquired MR signal datasets.
6. The method according to claim 5, wherein the movement of the interventional tool (19) with respect to the body part (22) (10) is detected by detecting a deviation of the movement of the interventional tool (19) from a repetitive movement pattern based on repeatedly collected monitoring data.
7. The method of claim 1, wherein the pulse train is a PROPELLER sequence, wherein the position and/or rotation of the individual k-space blades of the PROPELLER sequence is corrected in step b) based on the collected monitoring data.
8. Apparatus for magnetic resonance imaging (MRI) for implementing the method according to paragraphs. 1-7, moreover, the MRI apparatus (1) includes at least one main magnetic coil (2) for generating a uniform constant magnetic field in the study area, a number of gradient coils (4, 5, 6) for generating switchable magnetic field gradients in in different directions in space in the study area, at least one RF coil (9) for generating RF pulses in the study area and / or for receiving MR signals from the patient's body (10) located in the study area, a control unit (15) for monitoring of the time sequence of RF pulses and switchable magnetic field gradients and a reconstruction unit (17), moreover, the specified MRI apparatus (1) is configured to perform the following steps:
a) collecting tracked data from at least one micro-coil attached to an interventional tool (19) introduced into the moving part (22) of the body (10),
b) exposing the part (22) of the body (10) to a pulse sequence comprising RF pulses generated by the RF coil (9) and switchable magnetic field gradients generated by the gradient coils (4, 5, 6) to obtain one or more MR signals from the part (22), wherein the movement and/or rotation parameters describing the movement of the body part (22) (10) are derived from the tracked data, the pulse train parameters being corrected so as to compensate for the movement in the image by means of a shift or rotation when scanning in accordance with the parameters of movement and/or rotation, using the control unit (15) and/or reconstruction unit (17) based on the tracked data,
c) obtaining an MP signal data set by repeating steps a) and b) several times,
d) reconstructing one or more MR images from the MR signal data set.
9. An MRI apparatus according to claim 8, wherein the monitored data is collected by the MRI apparatus (1) in the form of MR signals generated or detected by at least one RF microcoil (20).
10. The MRI apparatus of claim 8, also including an instrument tracking system for collecting tracked data in step a).
11. An information carrier containing computer-executable commands for instructing the computer to carry out the method of magnetic resonance (MR) tomography of the moving part (22) of the patient's body (10) placed in the area of study of the MRI apparatus (1), comprising the steps of:
a) collect tracked data from at least one microcoil attached to the intervention tool (19),
b) generating a sequence of pulses to obtain one or more MR signals from a moving part of the body of the patient, and the parameters of movement and/or rotation describing the movement of the part (22) of the body (10) are derived from the tracked data, and the parameters of the sequence of pulses are corrected so that compensate for movement in the image by shifting or rotating during scanning in accordance with the parameters of translation and / or rotation,
c) obtaining the MP signal data set by repeating steps a) and b) several times,
d) reconstructing one or more MR images from the MR signal data set.
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SUBSTANCE: group of inventions relates to medical equipment, namely to magnetic resonance imaging systems. The medical device includes a magnetic resonance imaging system that includes a magnet, a clinical device, and a slip ring assembly capable of supplying power to the clinical device. The slip ring assembly comprises a cylindrical body, a rotary element on which the clinical device is mounted, the first cylindrical conductor and the second cylindrical conductor, which partially overlap. The second cylindrical conductor is connected to the cylindrical body, the first cylindrical conductor and the second cylindrical conductor are electrically isolated. The slip ring assembly also includes a first set of conductive elements, each of the set of conductive elements being connected to a second cylindrical conductor, and a brush holder assembly comprising a first brush and a second brush, wherein the first brush is configured to contact the first cylindrical conductor when the rotary element rotates. around the axis of symmetry. The second brush is configured to make contact with the set of conductive elements when the rotary element rotates around the axis of symmetry. EFFECT: inventions make it possible to weaken the magnetic field generated by the slip ring assembly. 2 n. and 13 z.p. f-ly, 7 ill.
The group of inventions relates to the field of medicine. A method for magnetic resonance imaging of a moving part of a patient's body placed in the area of study of an MRI apparatus, the method comprising the steps of: of the body by a pulse train to receive from it one or more MR signals, and the movement and/or rotation parameters describing the movement of the body part are derived from the tracked data, and the pulse train parameters are corrected so as to compensate for movement in the image by shifting or rotating during scanning in accordance with with translation and/or rotation parameters, c) obtaining a set of MR signal data by repeating steps a) and b) several times, d) reconstructing one or more MR images from the set of MR signal data. At the same time, the MRI apparatus for implementing the method includes a main magnetic coil for generating a uniform constant magnetic field in the study area, a number of gradient coils for generating switchable magnetic field gradients in different directions in space in the study area, an RF coil for generating RF pulses in the study area and or for receiving MR signals from the patient's body located in the study area, a control unit for controlling the time sequence of RF pulses and switchable magnetic field gradients, and a reconstruction unit. The information carrier contains computer-executable commands for implementing the MRI method of a moving part of the patient's body placed in the area of study of the MRI apparatus. The use of this group of inventions will reduce the scanning time and provide effective motion compensation. 3 n. and 8 z.p. f-ly, 2 ill.
Interventional radiology a branch of medical radiology that develops the scientific foundations and clinical application of therapeutic and diagnostic manipulations carried out under the control of radiation research. R.'s formation and. became possible with the introduction of electronics, automation, television, and computer technology into medicine. The technology of interventional interventions is based on the use of electro-optical converters, X-ray television devices, digital (digital) radiography, devices for high-speed X-ray photography, X-ray cinematography, video magnetic recording, devices for ultrasonic and radionuclide scanning. A big role and R.'s development and. the development of a technique for percutaneous catheterization of blood vessels and the design of special instruments for catheterization of blood vessels, bile ducts, ureters, targeted punctures and biopsies of deeply located organs played a role. Interventions consist of two stages. The first stage includes a radiation study (, computed tomography, ultrasound or radionuclide, etc.), aimed at establishing the nature and extent of the lesion. At the second stage, usually without interrupting the study, he performs the necessary therapeutic manipulations (catheterization, puncture, etc.), which are often not inferior in efficiency, and sometimes even superior to surgical interventions, and at the same time have a number of advantages compared to them. They are more gentle, in most cases do not require general anesthesia; the duration and cost of treatment are significantly reduced; the percentage of complications and decrease. Interventional interventions can be the initial stage in the preparation of severely weakened patients for the operation required in the subsequent operation. R.'s development and. required the creation of a specialized office as part of the radiology department. Most often it is angiographic for intracavitary and intravascular studies, serviced by an X-ray surgical team, and which includes an X-ray surgeon, a specialist in ultrasound diagnostics, X-ray technician, nurse, photo lab technician. Employees of the X-ray surgical team must master the methods of intensive care and resuscitation. Indications for interventional interventions are very wide, which is associated with a variety of tasks that can be solved using the methods of interventional radiology. General contraindications are the serious condition of the patient, acute, mental disorders, functions of the cardiovascular system, liver, kidneys, when using iodine-containing radiopaque substances - increased to iodine preparations. Preparation of the patient begins with explaining to him the purpose and methodology of the procedure. Depending on the type of intervention, different forms of premedication and anesthesia are used. All interventional interventions can be conditionally divided into two groups: X-ray endovascular and extravasal. X-ray endovascular interventions, which have received the most recognition, are intravascular diagnostic and therapeutic manipulations carried out under x-ray control. Their main types are X-ray endovascular, or angioplasty, X-ray endovascular prosthetics and X-ray endovascular. X-ray endovascular dilatation is one of the most effective ways treatment of limited (usually no more than 10 cm) segmental stenoses of vessels. This method is used in approximately 15% of patients requiring surgical treatment of occlusive vascular lesions. X-ray endovascular dilatation is performed with atherosclerotic narrowing coronary arteries heart, stenosis of the brachiocephalic branches of the aortic arch, stenosis of the renal arteries of a fibromuscular or atherosclerotic nature, with narrowing of the celiac trunk and upper mesenteric artery, with occlusive lesions of the general and external iliac arteries and vessels of the lower extremities. X-ray endovascular dilation is performed under local anesthesia. First, in the affected through angiographic enter radiopaque agent for exact definition localization of stenosis, its degree and nature ( rice. one
). A therapeutic double-lumen catheter, such as a Gruntzig catheter, is then inserted into the lumen of the angiographic catheter. It consists of a main tube with a hole at the end and a polyethylene sheath surrounding it, forming near end section balloon expansion. Thus, there are two gaps in the Gruntzig balloon: one internal and the second - between the main catheter and its sheath. After removal of the angiographic catheter, the conductor of the therapeutic catheter is carefully introduced into the area of stenosis under the control of X-ray television. A syringe equipped with a manometer is used to infuse a dilute radiopaque substance into the lumen formed by the inner tube and the sheath, as a result of which the balloon, evenly stretching, exerts pressure on the walls of the narrowed part of the vessel. Dilatation is repeated several times, after which the catheter is removed. In the atherosclerotic process, under the influence of compression, atheromatous plaques are crushed and pressed against the vessel wall. Contraindications are diffuse stenoses, sharp bends and twisting of the arteries, eccentric location of the stenosis site. X-ray endovascular dilatation can be accompanied by complications, among which there are bleeding at the puncture site of blood vessels, arteries and (the most dangerous) thrombus formation, as well as detached atheromatous masses. The disadvantage of X-ray endovascular dilatation is the occurrence of restenosis. To expand the lumen of the vessel, the use of laser tunneling has begun. It is carried out into the affected artery, equipped with fiberglass optics, which serves as a conductor for laser beam causing "evaporation" of atheromatous plaque. X-ray endovascular prosthesis is the introduction of an endoprosthesis into the expanded area of the vessel, which makes it possible to avoid restenosis after endovascular dilatation. There are self-expanding and inflatable steel, as well as spiral prostheses made of nitinol, which is an alloy of nickel and titanium. Nitinol has high elasticity and the ability to restore the previously given to it certain conditions shape. The straightened nitinol wire passed through the catheter, under the influence of blood temperature, takes the previous form of a spiral and serves as a supporting frame, preventing restenosis. gradually covered with fibrin and overgrown with endothelial cells. X-ray endovascular occlusion is the introduction of some material (embolus) into a blood vessel through a catheter for the purpose of temporary or permanent obturation of its lumen. It is more often used to stop bleeding (pulmonary, gastric, hepatic, intestinal), the source of which is previously established using endoscopic, radiation and other studies. The introduction and advancement of a catheter made of an elastic radiopaque material is carried out according to the Seldinger method. When the catheter reaches the intended level, angiography is performed, and then embolization. The material for the embolus is selected in each case individually, taking into account the nature of the pathological process and the caliber of the artery. Dissolving emboli are administered for temporary vascular lumen occlusion, insoluble emboli for permanent occlusion. Substances harmless to the body are used: gelatinous hemostatic sponges, muscular , blood clots, plastic or metal, Teflon threads, silicone and latex tear-off cans. Persistent embolization allows you to get a Gianturco spiral, which is a coil of elastic steel wire with woolen and (or) Teflon threads 4-5 long reinforced at the end cm. The proximal end of the coil has a blind channel for insertion of the axial stylet, which allows the wire to be straightened out to be inserted into the catheter. In the blood vessel, the helix returns to its original shape and becomes a scaffold for thrombus formation. In the area of adherence of the spiral to the intima of the vessel, aseptic occurs, which contributes to the organization of the thrombus. Most often, X-ray endovascular occlusion is used to treat extensive hemangiomas in hard-to-reach areas. X-ray endovascular occlusion has gained recognition in lung diseases accompanied by repeated hemoptysis and recurrent pulmonary bleeding. Based on the data x-ray examination source of hemoptysis, perform catheterization of the bronchial vessel supplying blood to the affected lung. After clarifying the nature of pathological changes in the arteries using arteriography, embolization is performed. Endovascular embolization is used for thrombosis of aneurysms, separation of congenital and acquired arteriovenous fistulas, closure of an ungrown arterial (bothallus) duct and a defect in the heart septum. Endovascular embolization is sometimes used to reduce vascularity. malignant neoplasm, incl. before surgical intervention, which can help reduce blood loss during surgery (for example, with a kidney). A complication of X-ray endovascular occlusion is tissue, leading in some cases to the development of a heart attack. The procedure may be accompanied by local temporary pain, nausea, fever. X-ray endovascular interventions include many other manipulations: transcatheter, transcatheter removal of foreign (for example, from the pulmonary artery and the heart cavity), dissolution of blood clots in the lumen of blood vessels. Great progress has been made in the thrombolytic therapy of patients with acute infarction myocardium, thromboembolism pulmonary arteries as well as in the treatment acute pancreatitis, and in particular pancreatic necrosis, by transcatheter long-term regional infusion of therapeutic drugs. Methods for the selective administration of chemotherapeutic drugs and radioactive substances are used in oncology. One of the directions of X-ray endovascular interventions is the transcatheter destruction of the tissues of some organs (for example, the adrenal glands in severe Itsenko-Cushing's disease, the spleen in a number of blood diseases). For this purpose, several milliliters of a radiopaque substance are injected through a catheter into the outlet vein of the corresponding organ, as a result of which the vessel ruptures, and the radiopaque substance enters the parenchyma. The resulting tissue causes destruction of the organ tissue, which can contribute to the rapid elimination of the clinical manifestations of the disease (an effect similar to the removal of the adrenal glands and splenectomy). A frequent X-ray endovascular intervention is a special filter in the inferior vena cava (kava filter). This operation is performed in patients who are threatened by the pulmonary arteries (in particular, with thrombophlebitis of the deep veins of the pelvis and lower extremities). Having established the presence of thrombosis and its localization with the help of ultrasound and phlebography, catheterization of the vena cava is carried out and strengthened in the lumen. Extravasal interventional interventions include endobronchial, endobiliary, endoesophageal, endourinal and other manipulations. X-ray endobronchial interventions include catheterization bronchial tree, performed under the control of X-ray television transillumination, in order to obtain material for morphological studies from areas inaccessible to the bronchoscope. With progressive strictures of the trachea, with softening of the cartilage of the trachea and bronchi, temporary and permanent metal and nitinol prostheses are used. Endobiliary X-ray surgical interventions are being improved. With obstructive jaundice, through percutaneous puncture and catheterization of the bile ducts, they are decompressed and an outflow of bile is created - external or internal bile ducts ( rice. 2
). Preparations are injected into the bile ducts to dissolve small stones, small stones are removed from the ducts with the help of special tools, biliodigestive fistulas are expanded, in particular, anastomoses between the common bile duct and the duodenum when it narrows. In sharply weakened patients with acute cholecystitis, transcatheter obliteration is performed. cystic duct, after which anti-inflammatory therapy is carried out, culminating in crushing and removal of calculi. Percutaneous gastrostomy, jejunostomy, and cholecystostomy are increasingly being used. To eliminate narrowing of the digestive canal, incl. esophagus, perform balloon dilatation ( rice. 3
). The basis of X-ray endourinal manipulations is most often percutaneous and catheterization of the renal pelvis with obstruction of the ureter. In this way, manometry and contrasting of the pelvicalyceal system (antegrade pyelography) are carried out, medicinal substances are administered. Through an artificially created nephrostomy, a biopsy, stricture of the ureter and its balloon expansion are performed. Noteworthy is dilatation and endoprosthetics of the urethra in case of adenoma. prostate and similar manipulations for cervical stricture. Interventional methods for examining the fetus and treating its diseases are coming into practice. So, under the control of ultrasound scanning, an early biopsy of the chorion, fetal skin, blood sampling, and elimination of urinary tract obstruction are carried out. Interventional studies are used for puncture of non-palpable formations in the mammary gland, identified by mammography. The puncture is performed under the control of X-ray television transillumination. After the study, a special needle is left in the gland tissue, which serves as a guide for sectoral resection. Under the control of fluoroscopy or computed tomography, percutaneous transthoracic punctures of intrapulmonary and mediastinal formations are performed. Similarly, incl. under the control of ultrasound scanning, puncture and biopsy of pathological foci in other tissues and organs are performed. The most common interventional manipulations were puncture and abscesses of various localization with their subsequent drainage. The technique is used for cysts of the thyroid, pancreas, kidneys, liver, etc., abscesses of the lungs, liver, pancreas, and abdominal cavity. puncture with a stylet catheter under the control of ultrasound scanning, computed tomography or fluoroscopy. After removal of purulent contents through the catheter, drugs are poured into the cavity. left in the cavity to repeat the procedure. With the help of radiation research methods, the dynamics of the process is observed. Bibliography: Rabkin I.Kh. X-ray endovascular prosthetics. , No. 6, p. 137, 1988; Rabkin I.Kh., Matevosov A.L. and Getman L.I. X-ray endovascular, M., 1987. Rice. 2b). Cholangiograms of a patient with a stricture of the common bile duct: after dilatation of the common bile duct, a plastic endoprosthesis was introduced into it (indicated by arrows).
1. Small medical encyclopedia. - M.: Medical Encyclopedia. 1991-96 2. First health care. - M.: Bolshaya Russian Encyclopedia. 1994 3. encyclopedic Dictionary medical terms. - M.: Soviet Encyclopedia. - 1982-1984.
- Radiology, military
See what "Interventional Radiology" is in other dictionaries:
Radiology branch of medicine that studies the use of ionizing radiation for diagnosis (radiodiagnosis) and treatment (radiotherapy) various diseases, as well as diseases and pathological conditions arising from exposure ... ... Wikipedia
I Radiology medical field clinical medicine studying the application x-ray radiation to study the structure and functions of organs and systems, as well as to diagnose human diseases. Originated at the end of the 19th century. after opening in 1895 ... ... Medical Encyclopedia
Chronic relapsing disease, the main symptom of which is the formation of a defect (ulcer) in the wall of the stomach or duodenum. In foreign literature, to refer to this disease, the terms "ulcer ... ... Medical Encyclopedia
I X-ray diagnostics recognition of injuries and diseases of various human organs and systems using X-ray examination. At the initial stage of development, the radiological region of R. was limited to studies of the respiratory organs ... ... Medical Encyclopedia
