Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.59 (MIP)
 4,906 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of this study was to analyse with 3D TOF MR angiography the anatomical variants of the circle of Willis (CW) in 109 consecutive patients. In all cases, the quality of exams was sufficient to analyse the anatomy of CW. Nevertheless, MRA over estimated hypoplastic segments because incomplete CW were more frequently demonstrated with MRA than in anatomic literature. This lack of MRA sensitivity was related to artifacts as MIP artifacts and blood flow artifacts. MRA sensitivity was improved by analysis of partitions with MIP reconstructions.
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PMID:[Anatomy of the circle of Willis with 3D time of flight magnetic resonance angiography and analysis of partitions]. 747 97

The diagnostic role of Magnetic Resonance Imaging (MRI) was investigated in the study of abdominal aortic aneurysms and compared with that of Computed Tomography (CT) and digital subtraction angiography (DSA). Magnetic Resonance angiography (MRA) was performed on 21 patients with radiologically proved abdominal aortic aneurysms, using a superconductive 1.5 T magnet (GE, Signa Advantage); the 2D TOF technique with gradient-echo sequences was used (SPGR: FA 45-60 degrees, TR/TE 33/7, ST 2 mm, 1 nex, 256 x 128 matrix, inferior presaturation and flow compensation). The images acquired on the axial plane were reconstructed according to MIP and rotated on the z-axis from +90 degrees to -90 degrees. In all cases SE 2D T1- and T2-weighted sequences were acquired on the axial plane. Twelve patients were examined with MRI, CT and DSA; 3 with MRI and CT; 2 with MRI and DSA and finally 4 with MRI only. The radiologic studies were then reviewed blind and the results of the different methods compared. In all cases MRI yielded similar information to CT and DSA as to aneurysm extent and size, vessel involvement, status of visceral, iliac and common femoral arteries and finally the conditions of perianeurysmatic tissues. The authors conclude that MRI is a useful and accurate technique for the preoperative examination of abdominal aortic aneurysm patients.
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PMID:[The magnetic resonance imaging of abdominal aortic aneurysms]. 782 72

MR angiography of the lumbar venous plexuses (MR venography, MRV) was performed with thirty-one cases using a 1.5 T superconducting MR unit. Two MRV techniques, FISP based subtraction method and FLASH based TOF method were used for this study. After obtaining coronal or axial data acquisition, angiographic images were reconstructed by MIP method. Gd-DTPA was injected in all cases. The over all detectability of the lumbar venous plexuses was more than 77% on coronal data acquisition with subtraction method that better delineated slow-in-plane flow with optimal tissue signal suppression around the vessels. The coronal images were superior to axial ones in terms of wider demonstration of vertebral venous plexuses. Whole lumbar spine can be demonstrated in coronal plane. The use of Gd-DTPA to reduce the saturation effect of venous flow was necessary for better visualization of the lumbar venous plexuses.
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PMID:[2D MR angiography of lumbar venous plexuses]. 812 69

This work was aimed at investigating the diagnostic role of Magnetic Resonance angiography (MRA) versus spin-echo images in the study of carotid paragangliomas. Ten patients affected with carotid paragangliomas were studied; surgery was the gold standard. MR examinations were performed with a superconductive 1.5 T magnet and a linear head coil. T1-weighted (TR 500 ms, TE 15 ms, 256 x 256 matrix) and T2-weighted (TR 2000 ms, TE 15/90 ms, 256 x 256 matrix) spin-echo sequences were acquired. TOF 3D (flash: FA 25 degrees, TR 30 ms, TE 7 ms) MRA images were acquired; coronal and sagittal images were rotated according to the MIP. Spin-echo images demonstrated the typical "salt and pepper" pattern in all cases. In 6 cases (lesion diameter > 3 cm) the vascular structures of the paragangliomas and carotid dislocation were clearly demonstrated by MRA. MRA also depicted carotid dislocation in all cases. In conclusion, in the evaluation of carotid paragangliomas > 3 cm diameter, MRA yields complementary information on vascular structures and dislocation of carotid vessels to spin-echo MR sequences.
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PMID:[Neoplasms of the glomus caroticum: magnetic resonance angiography versus magnetic resonance]. 812 36

This work was aimed at investigating the value of Gd-DTPA to demonstrate distal renal artery branches with 3D TOF Magnetic Resonance angiography (MRA). Ten volunteers and two patients with proximal-distal renal artery stenoses were studied with MRA; all subjects were studied before and after Gd-DTPA. MRA was performed with a 1.5-T superconductive magnet (Magnetom Siemens); the FISP 3D sequence was used with the following setting: FA 25 degrees, TR 40 ms, TE 6 ms, slice thickness 64 mm with 64 partitions and MA 256 x 256. This setting was not changed from pre- to post-contrast scans. The images acquired on the z axis were rotated, according to the MIP, on the axial and the sagittal axes, from 0 degrees to 180 degrees, with a 15 degrees step. 0.2 ml/kg of Gd-DTPA were injected as bolus during 3D acquisitions; the injection was started half-way through acquisition. To evaluate and compare pre- and post-contrast MRA images, the signal-to-noise (S/N) ratio and the demonstration of the various renal artery segments were studied. Average S/N ratio was 2.3 in the right renal artery and 2.1 in the left renal artery on pre-contrast MRA images, while it was 0.9 in the left renal artery and 0.8 in the right renal artery on post-contrast MRA images. These differences were statistically significant (p < 0.01). As for the demonstration of the distal segments and of the bifurcations, enhanced MRA was no better than unenhanced MRA. As for the demonstration of distal segment stenoses, enhanced MRA proved no better than unenhanced MRA in both patients. To conclude, in our experience MRA after Gd-DTPA failed to allow the systematic demonstration of the distal segments and of the bifurcations of the renal arteries.
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PMID:[Renal arteries: angiography with TOF 3D magnetic resonance with and without contrast media (Gd-DTPA)]. 814 62

The reliability of Magnetic Resonance Angiography (MRA) was investigated in the study of stenosis and obstruction of carotid bifurcation; digital carotidography was the gold standard. Twenty-five consecutive patients with clinical suspicion of cerebrovascular insufficiency entered the study. MRA was performed with a 1.5 T superconductive magnet (Magnetom Siemens) and a linear head coil. The TOF 3D (FA 20 degrees, TR 30 ms, TE 7 ms) technique was applied. Images were acquired on the sagittal plane and rotated in postprocessing according to MIP on the z axis from 60 to 120 degrees (step 5). MRA exhibit 80.5% sensitivity, 96% specificity, 89.4% accuracy, 94.7% positive predictive value and 86.3% negative predictive value. When calculating the interrupted flow relative to hemodynamically significant stenoses (range 31%-occlusions), MRA sensitivity was 80.5%, specificity 100%, negative predictive value 86.3%, positive predictive value 94.7% and overall diagnostic accuracy 91.2%. MRA is to be considered a diagnostically reliable procedure in the study of carotid bifurcation and its diagnostic accuracy may even be increased in the future by the possible assessment of over- and underestimated cases.
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PMID:[Carotid bifurcation: angiography with magnetic resonance versus carotid angiography]. 821 May 34

The diagnostic role of Magnetic Resonance angiography (MRA) was investigated in the study of the abdominal aorta. To obviate the problems relative to motion and respiratory artifacts, the TOF 2D (FISP 2D) technique was employed, together with a superconductive 1.5 T magnet. Fourteen volunteers were studied. The images acquired on the coronal and sagittal planes were processed according to MIP and target MIP, with a rotation on the z axis. The abdominal aorta was clearly demonstrated in 100% of cases, the celiac trunk in 42.8% of cases on coronal and in 100% on sagittal images. The superior mesenteric artery was depicted in 35.7% of cases on coronal and in 100% of subjects on sagittal acquisitions. The renal and iliac arteries were demonstrated in 100% of cases on coronal images only, while dorso-spinal and lumbar arteries were always clearly depicted on sagittal scans only. To evaluate the diagnostic reliability of MRA, 6 patients with abdominal aortic aneurysms were also studied and angiography and surgery were assumed as the gold standard. In all cases MRA yielded similar information to angiography and surgery as to aneurysm extent, vessel involvement and left renal vein course; moreover, MRA allowed the assessment of both the thrombotic and the calcific components of the aneurysm. Unenhanced MRA with the TOF 2D technique allows the detailed depiction of the aorta in about 20 minutes. Our preliminary results in the study of aneurysms are encouraging relative to the future diagnostic role of MRA in the abdominal aorta.
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PMID:[Abdominal aorta: role of angiography with magnetic resonance]. 849 62

The diagnostic role of Magnetic Resonance Angiography (MRA) was investigated in the study of the thoracic and abdominal aorta. Thirty-two patients with different conditions were examined: the thoracic aorta was affected in 7 cases (3 aneurysms, 2 dissections, 2 tumors) and the abdominal aorta in 25 cases (21 aneurysms, 3 stenoses and 1 dissection). Moreover, 2 kinkings and 1 dextroposition of the thoracic aorta were observed as occasional findings, together with 15 abdominal aorta kinking cases. A 1.5-T superconductive magnet (Magnetom, Siemens) with circular polarization body coil and the 2D TOF (FL 18 degrees, TR 30 ms, TE 10 ms, ST 5 mm, 1-mm overlap) technique were used. The images acquired on the coronal and sagittal or parasagittal planes were rotated from -45 degrees to 45 degrees and from 60 degrees to 120 degrees during post-processing, according to MIP. Digital angiography was the gold standard in all cases, angiography and CT were the gold standards for aneurysms, and surgery for the lesions reaching the thoracic aorta. The 2D TOF technique allowed excellent visualization of both the thoracic and the abdominal aorta. In thoracic aorta conditions, MRA always identified aneurysms and assessed their relationship to epiaortic branchings. Moreover, MRA identified 2 cases of thoracic aorta dissection. In one case (1/2) MRA failed to depict aortic wall infiltration by tumor. In 21 abdominal aorta aneurysms, MRA always correctly demonstrated both the extent of the aneurysm and its relationships to renal and iliac arteries. Moreover, the thrombotic aneurysmal component was demonstrated, together with left renal vein course, which was retroaortic in 4 cases. Abnormal course, stenoses (2 cases) and dissection of the abdominal aorta were always identified by MRA.
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PMID:[2D TOF angio-MR of the thoraco-abdominal aorta. Technique and clinical applications]. 851 60

This work was aimed at investigating the diagnostic accuracy of Magnetic Resonance Angiography (MRA) in the study of the portal vein in liver transplant recipients. Ten patients (7 men and 3 women; mean age: 45 years) were examined 7-180 days after transplantation. The indications to liver transplant follow: post-infective active chronic hepatitis (4 patients), post-alcoholic chronic hepatitis (2 patients), HCC (2 patients), sclerosing cholangitis (1 patient) and primary biliary cirrhosis (1 patient). MRA images were acquired with the 2D TOF technique (TR 50 ms, TE 6.9 ms; FA 30 degrees, 40 slices; 6-mm thickness with 1-mm overlapping; 2 averages; 7.06 TA; matrix: 192 x 256). Axial scans were reconstructed with the MIP technique. Phase contrast sequences with retrospective cardiac triggering were also acquired for flow quantitation (TR/TE/FA: 26/9.3/20 degrees; FOV 150; matrix: 96 x 128; 4 averages, VENC = 20 cm/s). MRA yielded good quality images of the anatomy of the main portal vein and of the bifurcation in all cases, while a signal loss was observed in the peripheral branches. In all cases, the anastomosis could be studied at the portal vein. On MIP reconstructed images, the anastomosis appeared as a relative stenosis (4), while on 2D images it appeared as a small hypodense area on the vessel margin, because of the slight paramagnetic effect of the vascular suture. No thrombi were depicted in any patient and flow was hepatopetal in all cases. In conclusion, MRA is a useful tool for portal system studies in liver transplant recipients, because it permits the panoramic depiction of the portal system and the quantitation of flow (10).
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PMID:[Magnetic resonance angiography of the portal vein in liver transplant recipients]. 883 Mar 62

The cost of treatment of ischemic stroke (second cause of death for elderly patients) is increasing. carotid bifurcation surgery can change the prognosis (as proven by NASCET and ECST studies) for symptomatic patients with over 70% of carotid narrowing. Exploration of the carotid bifurcation is an important step in the diagnosis and must assess the degree of stenosis, the smoothness of the plaque and describe the collateral vessels. Duplex sonography is used to analyze the plaque and to measure the hemodynamic consequences beyond the stenosis. Transcranial Doppler is used to study the hemodynamic consequences at the circle of Willis. 3D TOF MR Angiography visualizes vessels using MIP but with a risk of overestimation of the degree of stenosis. A good morphological study of the circle of Willis can be achieved. With spiral CT, 3D data bases can be acquired with a single injection of contrast medium. Analysis is based on native, reformatted and MIP images. The image quality is generally good, but decreases in the case of huge calcifications. Brain examination can be performed in the same session, looking for rupture of the blood-brain barrier. Angiography remains the gold standard with a high complication rate. It allows excellent analysis from the aortic arch to distal cortical vessels. Isotope studies are only performed in difficult cases (vertebro-basilar lesions, differential diagnosis). Duplex ultrasound is performed first in all protocols. Until recently, angiography was performed before surgery, but the current tendency is to use a less invasive examination (MR angiography or CT angiography) and angiography is then only performed when necessary. A knowledge of the respective advantages of each technique is essential in order to adapt the protocols to each local team.
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PMID:[Multimodal approach to carotid bifurcation in atherosclerosis]. 968 16


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