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Query: HUMANGGP:010955 (mda-7)
 464 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study was carried out to evaluate time-of-flight RA in renal artery stenosis (RAS) in selected hypertensive patients (n = 41). In i.a. DSA studies, 10 unilateral, 8 bilateral RAS, and 4 unilateral RA occlusions were proven. MRA was done in coronal and axial 2D technique (FLASH), and in 3D technique (FISP) using GE-pulse sequences. DSA results were correlated with both 2D-individual slices, 2D- and 3D-MIP angiograms. Highest sensitivity and specificity was found for the axial 2D individual slice analysis (88%, 85% resp.), followed by the 3D-MIP MRA (78%, 80% resp.), and axial 2D-MIP MRA (73%, 79% resp.). MRA of renal arteries used in this study shows to be not adequate to DSA results due to many drawbacks. All MRA techniques, in particular the 3D-technique, tend to overestimate RAS occasionally pretending occlusions.
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PMID:[The evaluation of 2D- and 3D-"time of flight" magnetic resonance angiography (MRA) in the diagnosis of renal artery stenoses]. 163 7

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 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 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

Twenty volunteers were examined by means of 2D and 3D time of flight (TOF) Magnetic Resonance angiography (MRA) of the renal arteries. The possible diagnostic applications of MRA were also evaluated in 6 patients with renovascular diseases. MRA examinations of the renal arteries were performed with a 1.5 T superconductive magnet (Magnetom Siemens) and circular body coil. Ten volunteers were studied with 3D FISP sequences (FA 25 degrees, TR 40 ms, TE 7 ms, ST 1 mm, Ma 256 x 256, FOV 500); the images were acquired on the axial plane and were rotated, in MIP and target MIP, on the axial (z) and sagittal (x) axes. The other 10 volunteers were studied with 2D FLASH sequences (FA 18 degrees, TR 300 ms, TE 8 ms, ST 4 mm, overlap 1 mm, Ma 256 x 256, FOV 500); the images were acquired on the axial and coronal planes and were rotated, in MIP and target MIP, on the axial (z) and sagittal (x) axes. The ostium and proximal segments (1-15 mm) were always easily identified with 2D and 3D sequences, the distal segments (16-35 mm) were also clearly demonstrated in 11 cases with 3D (55%) and in 16 cases with 2D (85%) sequences. The bifurcations and branch vessels of the renal arteries were easily depicted with 3D TOF sequences in 7 cases only. Combined 3D and 2D TOF images permitted the thorough evaluation of the renal arteries. In renovascular diseases, 2D and 3D TOF images clearly demonstrated occlusions and stenoses of the proximal segment (1-15 mm). 2D TOF sequences only permitted the visualization of a case of fibromuscular dysplasia in the distal segment. Our results suggest that 2D and 3D TOF MRA exhibits good potentials as a noninvasive screening technique for the evaluation of renovascular diseases.
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PMID:[Angiography with magnetic resonance++ of the renal arteries: bidimensional versus tridimensional "time of flight" technique]. 849 63

The aim of this work was to optimize the magnetic resonance angiography (MRA) technique for the selective study of the pulmonary veins. Twenty consecutive patients (13 men and 7 women; mean age: 30.5 years) were examined. MRA was performed with a 1 T superconductive magnet and the 3D time of flight (TOF) technique. Fast sequences (3D FISP: TR 58 ms, TE 6 ms, FA 20 degrees, matrix 192 x 256; and 2D FLASH: TR 44 ms, TE 10 ms, FA 30 degrees, matrix 192 x 256) were used. Coronal and sagittal images were submitted to MIP processing; presaturation pulses for the pulmonary arteries were located in the mediastinal region. In the right lung, 3D TOF on the coronal plane well showed 124 veins, while sagittal images showed 106 veins. In the left lung, 3D TOF on the coronal plane well showed 96 vessels, while sagittal images showed 44 vessels. In the right lung, 2D TOF on the coronal plane well showed 54 veins, while sagittal images showed 36 vessels. In the left lung, 2D TOF on the coronal plane well showed 22 vessels, while sagittal images showed 21 vessels. Therefore, 3D TOF yielded better results than 2D TOF (p < 0.05). To conclude, 3D TOF with contrast agent administration is a useful tool to study the pulmonary veins; those with a larger caliber are better depicted and the integration of coronal and sagittal images depicts more veins.
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PMID:[Magnetic resonance angiography in the study of pulmonary veins: TOF 3D versus 2D]. 924 15