***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Purpose : To prospect ively determine feasibility and diagnostic accuracy of 3D contrast-enhanced MR-angiography ( CE-MRA ) at 3.0 tesla ( T ) in patients with peripheral arterial occlusive disease .  Digital subtraction angiography ( DSA ) was used as reference st and ard . Material and Methods : Thirty consecutive patients with suspected peripheral arterial occlusive disease were examined on a 3.0 T MR system by using the integrated whole body coil . A 4-station examination protocol in hybrid technique was chosen , containing 2 gadodiamide injections , the first one for imaging the calf and foot arteries ( single-step technique ) and the second injection for the visualization of the aortoiliacal and femoral arteries ( bolus-chase MRA ) . All patients underwent DSA within the following 48 hours . The arterial tree of each leg was divided in 15 segments and 4 anatomic regions ( iliacal , femoral , popliteal/proximal calf , distal calf/foot ) . Two radiologists analyzed the MR-images with regard to image quality , grade of stenosis , and venous overlap . DSA-images were analyzed by 2 radiologists in consensus with regard to the stenosis grade . Results : Eight hundred eighty-five and 884 of 889 arterial segments at CE-MRA were rated with excellent or good diagnostic image quality by observer 1 and observer 2 , respectively . In only 3 segments image quality was affected by venous contamination . Sensitivity of CE-MRA for determination of relevant arterial stenoses ( 50%–99 % ) and occlusions — as compared with DSA — was 95.3 % ( both observer ) and specificity was 98.5 % and 97.8 % for observer 1 and observer 2 , respectively . Conclusion : Peripheral hybrid CE-MRA at 3.0 T is feasible and proved to be reliable at depiction of stenoses and occlusions of the whole pelvic and lower leg arterial system PURPOSE To prospect ively study the diagnostic performance of hybrid single-dose contrast-enhanced MRA of peripheral arterial disease ( PAD ) , with digital subtraction angiography ( DSA ) as the reference st and ard . MATERIAL S AND METHODS Hybrid MRA , combining time resolved imaging of contrast kinetics and two-station bolus-chase sequences , of lower limb was performed in 31 PAD patients ( 21 men , 10 women ; mean age , 72 years ) with two separate gadobenate dimeglumine ( 8 mL ) injections in each sequence . Two independent blinded readers analyzed the vascular stenosis ( 32 segments in each limb ) . Sensitivity , specificity , and accuracy in all vascular segments and segments below popliteal artery were calculated . Interobserver agreements on MRA and intermodality agreements between MRA and DSA were calculated by using k statistics . RESULTS Sensitivity , specificity , and accuracy of the hybrid MRA with regard to hemodynamically significant stenosis in all vascular segments were 92 % , 97 % , and 95 % for reader 1 , and 90 % , 92 % , and 92 % , for reader 2 , respectively . The interobsever agreements on MRA were good ( k = 0.77 - 0.74 ) for all- grade stenosis , and excellent ( k = 0.82 - 0.81 ) for hemadynamically significant stenosis . The intermodality agreements are good to excellent ( k = 0.73 - 0.94 ) . CONCLUSION Single-dose hybrid MRA is a safe and reliable noninvasive alternative to conventional DSA in the assessment of PAD patients The purpose of this study was to assess the diagnostic value of two-dimensional ( 2D ) MR subtraction angiography of lower extremities in patients with symptomatic peripheral arterial occlusive disease with conventional angiography as the st and ard of reference . Twenty patients were prospect ively included .  2D subtraction MR angiography ( MRA ) consisted of multisection gradient-recalled echo ( GRE ) acquisitions with the shortest TE available on our machine ( 4 msec ) , obtained in the coronal plane before and after intravenous bolus administration of gadolinium chelate . MR images were reconstructed after subtraction with a maximum-pixel-intensity-projection ( MIP ) algorithm . MRA was performed in all cases 1 - 4 days before diagnostic angiography . In a prospect i ve blinded analysis , the number and location of significant ( ie , > 50 % ) stenoses and occlusions were evaluated for each vascular segment . Sensitivity and specificity were used to evaluate MRA data . Significant stenoses ( 38 of 46 , 83 % ) and occlusions ( 66 of 67 , 99 % ) seen at conventional angiography were identified with MRA . The sensitivity and specificity of MRA  for determination of stenoses > 50 % or occlusions was 100 % and 97 % , respectively . The location and extent of stenoses and /or occlusions on MRA and angiograms were well correlated ( kappa values , r = .73 , P < .05 ) . Contrast 2D MR subtraction angiography , by providing comparable information to that of conventional angiography , is well suited to evaluate the presence and severity of atherosclerotic lesions of the lower limbs PURPOSE To prospect ively compare contrast-enhanced ( CE ) magnetic resonance ( MR ) angiography against digital subtraction angiography ( DSA ) in patients with critical lower-limb ischemia . MATERIAL S AND METHODS Thirty patients with critical lower limb ischemia underwent both CE MR angiography and DSA . CE MR angiography commenced with a dedicated high-resolution study of the below-knee arteries followed by a three-station bolus-chase examination . Two blinded observers recorded the severity of the most significant stenosis within each arterial segment . Interobserver agreement was calculated and , with DSA as the reference st and ard , the sensitivity and specificity of CE MR angiography for the detection of significant stenosis ( > or=50 % luminal narrowing ) or occlusion was calculated . RESULTS All 390 arterial segments were scored by both observers . Sensitivity was higher in the distal segments ( 92%-96 % ) compared with the proximal segments ( 69%-79 % ) . Specificity was similar in distal ( 90%-91 % ) and more proximal segments ( 86%-96 % ) . Overall , interobserver agreement was excellent ( kappa = 0.95 for CE MR angiography and DSA ) and was superior within the distal segments . Twenty-eight segments that were considered occluded on DSA were shown to be patent on CE MR angiography and 16 segments that were considered occluded on CE MR angiography were shown to be patent on DSA . CONCLUSIONS In patients with critical lower-limb ischemia , CE MR angiography with high-resolution distal imaging is highly accurate for assessment of the below-knee arteries . Both DSA and CE MR angiography may identify patent vessels that are considered occluded based on the other modality The purpose of this study was to include the pedal vasculature into the coverage of peripheral multistation magnetic resonance angiography ( 3DceMRA ) . A total of 216 patients suffering from peripheral vascular disease were examined with a modified hybrid dual-bolus technique . The cruropedal arteries were acquired first with two sagittal slabs and time-resolved 3D sequences . Then the aortofemoral vessels were visualized using the bolus-chase technique and a second contrast injection . Interventional procedures were performed in 104 patients , and in 69 of those , the cruropedal vessels were also examined with digital subtraction angiography ( iaDSA ) . Using 3DceMRA , the cruropedal arteries were displayed with both excellent and good quality in 95 % ( 205/216 cases ) , and without any venous overlay in 94 % ( 203/216 cases ) . The aortofemoral vessels were not jeopardized by the first contrast injection . With iaDSA as the st and ard of reference , observed sensitivity of 3DceMRA was found in ranges from 80 % ( 29 % , 99 % ) to 100 % ( 86 % , 100 % ) for assessing significant stenoses , and observed specificity ranged between 93 % [ 80 % , 98 % ] and 100 % ( 82 % , 100 % ) . In conclusion , hybrid dual-bolus 3DceMRA significantly reduces the limitations of st and ard single-bolus 3DceMRA in anatomic coverage and temporal resolution of the cruropedal arteries , thus providing high- quality images of the entire peripheral vasculature PURPOSE To prospect ively determine feasibility of contrast material -enhanced magnetic resonance ( MR ) angiography of the peripheral arteries from distal aorta to pedal arteries with a 1.0-T system and a dedicated phased-array coil . MATERIAL S AND METHODS Twenty-seven patients with peripheral arteriosclerotic occlusive disease underwent contrast-enhanced MR angiography with an automatic moving-table technique . In addition , lower-leg and pedal arteries were examined without table movement ( hybrid technique ) . Two radiologists independently review ed MR angiograms to assess image quality and grade stenosis in 13 segments per leg . Each was blinded to patients ' clinical data . Twenty-five of the patients also underwent conventional angiography .  Stenosis grade at conventional angiography was assessed by two radiologists in consensus . Interobserver variability for stenosis grade at MR angiography was calculated with Cohen kappa test . Specificity and sensitivity of MR angiography  in detection of stenosis of more than 50 % and occlusion were calculated for both observers . The study was approved by the local ethics committee . RESULTS In 14 of the 27 patients , hybrid technique was superior to moving-table technique because there was less venous overlap ( 11 patients ) , fewer motion artifacts ( one patient ) , or both ( two patients ) . In nine patients , there was no difference between techniques ; in four patients , moving-table technique was superior . Stenosis grade was analyzed in 698 segments with MR angiography and in 638 segments with both conventional and MR angiography . Kappa analysis of interobserver agreement with MR angiography yielded a score of 0.84 . For the 638 segments evaluated with both conventional and MR angiography , observers 1 and 2 assigned same grade of stenosis with both modalities in 558 and 555 segments , respectively . Sensitivity for stenoses greater than 50 % and occlusion was 94.4 % and 91.1 % for observers 1 and 2 , respectively , and specificity was 90.6 % and 91.3 % . More distal runoff vessels were shown with MR angiography in seven cases and with conventional angiography in two cases . CONCLUSION Contrast-enhanced MR angiography of the peripheral vessels with a 1.0-T system and dedicated peripheral angiography coil is feasible , and in some cases , it provides additional information compared with conventional angiography Purpose : To determine whether contrast-enhanced 3D MR angiography ( CE MRA ) could replace digital subtraction angiography ( DSA ) for the evaluation of atherosclerotic peripheral vascular disease of the lower leg and foot . Material and Methods : Thirty-five patients with symptoms of atherosclerotic disease of the leg were examined prospect ively with CE MRA of the foot and the lower legs as well as with DSA from the aorta to the pedal arches . The MRA technique was focused on optimal imaging of the arteries of the foot . Results : The agreement between CE MRA and DSA  for grading of stenosis was moderate to good ( weighted κ-values 0.48–0.80 ) . The sensitivity of CE MRA  for detection of significant stenosis ( ≥ 50 % ) was 92 % and the specificity was 64 % with DSA as gold st and ard . Conclusion : CE MRA is a fairly accurate method for the demonstration of atherosclerotic disease below the knee including the pedal arches . It can replace DSA for the assessment of distal arteries in patients with impaired renal function . However , image quality and resolution still needs to be improved before CE MRA can become the method of choice in all patients PURPOSE To prospect ively compare the accuracy of 16-detector row computed tomographic ( CT ) angiography with conventional digital subtraction angiography ( DSA ) as the reference st and ard in the assessment of aortoiliac and lower extremity arteries in patients with peripheral arterial disease . MATERIAL S AND METHODS This study was approved by the institutional review board , and informed consent was obtained . A total of 39 consecutive patients ( 27 men [ mean age , 66 years ] and 12 women [ mean age , 64 years ] ) with peripheral arterial disease underwent both conventional DSA and 16-detector row CT angiography .  For data analysis , the arterial vascular system was divided into 35 segments . A total of 1365 arterial segments were analyzed for arterial stenosis by two independent blinded readers using a four-point grading system ( grade 1 , < 10 % luminal narrowing ; grade 2 , 10%-49 % luminal narrowing ; grade 3 , 50%-99 % luminal narrowing ; grade 4 , occlusion ) . Interobserver agreements were calculated by using kappa statistics . A third independent blinded reader assessed possible reasons for disagreements between 16-detector 
    Output:
    
Conclusion CTA and CE-MRA are accurate techniques for evaluating disease severity of aortotibial arteries in patients with CLI or IC .
No significant differences in the diagnostic performance of the two techniques between patients with CLI and IC were found .
Key Points• Computed tomography and contrast-enhanced magnetic resonance angiography can both demonstrate arterial disease.• CTA and CE-MRA can both accurately evaluate arteries in peripheral arterial disease.• Diagnostic performances of critical limb ischaemia and intermittent claudication are not different.• Separate imaging technique of tibial arteries by CE-MRA is preferred.• CTA and CE-MRA can distinguish confidently between high- grade stenoses and occlusions