This study shows the normal flow pattern in the descending thoracic aorta and its reversal in coarctation due to collateral flow. Thus, VENC-MR can measure collateral flow in coarctation and serves as a unique method for providing this important measurement of the severity of coarctation of the aorta.

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Neuroprotected CAS is associated in about 25% of cases with predominantly silent cerebral ischemia. Our findings suggest manipulation of endoluminal equipment in the supraaortic vessels to be a major risk factor for cerebral embolism during neuroprotected CAS.

The purpose of this study was to evaluate our capability to use coronally acquired. cardiac-gated two-dimensional phase-contrast MR angiography (MRA) to correctly detect and grade arteriosclerotic lesions from the aortic bifurcation to the popliteal artery. SUBJECTS AND METHODS. One hundred fifteen patients with a total of 253 arteriosclerotic lesions proven by intraarterial digital subtraction angiography were examined prospectively by two-dimensional phase-contrast MRA. MRA was perfirmed from the aortic bifurcation to the popliteal trifurcation. Imaging paranleters were TRITE. 83/9 msec; flip angle, I 1#{176}; matrix. 256 x 192: acquisitions. two; slice thickness. 80 mm: and field of view. 320 mm. ECG gating was used routinely and eight to 10 phases were acquired during the cardiac cycle. Velocity encoding was set to 30 cmlsec in the iliac arteries and to 20 em/sec in the femoral and popliteal arteries. Detected stenoses were graded in the following manner: I e4, to less than 50% stenosis, group 1 : 50 7c to less than 7SCk stenosis, group 2: 7SCk to less than I00% stenosis. group 3: and total occlusion, group 4. RESULTS. All arteriosclerotic lesions were revealed by MRA. Two hundred seventeen of 253 lesions were also graded correctly. Sensitivity was 95%, specificity was 90%. positive predictive value was 90%. and negative predictive value was 96%. The weighted kappa index was .92. Sensitivity and specificity for occlusions were both 1OO % ; for high-grade stenoses. 94% and 91 C4 respectively: for moderate stenoses. 84C/ and 94C% , respectively: and for mild stenoses. 79'F and lOOck. respectively. CONCLUSION. Two-dimensional phase-contrast MRA can provide MR angiograms with high sensitivity and specificity for high-grade stenoses in a reasonable amount of time in patients with peripheral artery occlusive disease.

The purpose of this study was to evaluate the capability of contrast-enhanced breath-hold fast imaging with steady-state precession (FISP) three-dimensional MR angiography (MRA) to detect stenotic lesions of the abdominal aorta, the renal arteries, and the iliac arteries by using a K-space-centered 20-ml gadolinium-diethylene pentaacetic acid (Gd-DTPA) bolus. Fifty patients were studied before conventional x-ray angiography. Contrast-enhanced breath-hold FISP three-dimensional MRA was applied in the coronal view, centered at the renal arteries. Twenty ml of Gd-DTPA was used in all subjects. A test bolus was applied to determine the injection time for the K-space-centered bolus injection. Of 300 segments, 284 segments were classified correctly, 11 were overestimated, and five were underestimated. Sensitivity was 98%, specificity was 96%, positive predictive value was 96%, negative predictive value was 98%, and accuracy was 97%. Of the 50 patients studied, 43 were staged correctly. No venous overlay was seen in 31 patients; partial overlay was seen in 16 patients, and venous structure overlay obscuring arterial anatomy was found in two patients. Six of nine accessory renal arteries could be identified by MRA. Intraobserver variability was .94. This study has shown the ability of contrast-enhanced breath-hold FISP three-dimensional MRA to detect and grade vascular lesions in the abdominal aorta and the renal arteries. The method may serve as a screening tool in the future.

Contrast-enhanced MR angiography is comparable to digital subtraction angiography for the detection of stenosis greater than 50% and occlusion in the iliofemoral arteries. Stent patency can be determined, but contrast-enhanced MR angiography is not suitable for stent evaluation owing to signal intensity dropout; however, it provides information about the vascular anatomic areas proximal and distal to the stent.

Bolus-chasing 3D-CE-MRA with manual table movement is a simple, robust and easy to perform technique which provides high quality angiograms of the lower extremity arterial system and is comparable to, i.a., DSA for the diagnosis of PVD.