Peripheral arteries in diabetic patients: standard bolus-chase and time-resolved MR angiography

PURPOSE: To prospectively determine the diagnostic performance of a combination of standard bolus-chase magnetic resonance (MR) angiography and MR angiography with time-resolved imaging of contrast kinetics (TRICKS) for depicting severity of peripheral vascular disease of the lower extremity, including the pedal arteries, in diabetic patients with digital subtraction angiography (DSA) as the reference standard. MATERIALS AND METHODS: An ethical committee approved this study; written informed consent was obtained from patients. Standard three-station and TRICKS MR angiography of the calf and foot were performed in 31 consecutive diabetic patients (23 men, eight women; mean age, 67 years; range, 43-81 years). Two readers separately assessed images of arterial segments as diagnostic or nondiagnostic and graded stenosis. Results were compared with those at DSA when the corresponding arterial segments were considered diagnostic at DSA. Wilcoxon signed rank test was used to determine if a significant difference between imaging techniques existed, and kappa statistics were used to determine interobserver agreement. RESULTS: The difference between standard MR angiography and DSA regarding the number of diagnostic segments in the thigh was not significant (P = .50). A significantly higher number of calf and foot segments was considered diagnostic at TRICKS MR angiography than at standard MR angiography (P < .025). Sixteen of 26 segments in the foot that were considered nondiagnostic at DSA were considered diagnostic at TRICKS MR angiography. Average sensitivity of standard MR angiography for depicting hemodynamically significant arterial stenosis was 84% (reader 1) and 83% (reader 2) in the thigh and 78% (reader 1) and 80% (reader 2) in the calf. For both readers, average specificity was 97% in the thigh and 90% in the calf. Sensitivity and specificity of TRICKS MR angiography in the calf and foot were improved compared with those at standard MR angiography. CONCLUSION: TRICKS MR angiography of the distal calf and pedal vessels is superior to standard MR angiography regarding the number of diagnostic segments and assessment of the degree of luminal narrowing.     

Peripheral vascular disease: comparison of continuous MR angiography and conventional MR angiography--pilot study

The aim of this study was to prospectively assess the accuracy of three-dimensional magnetic resonance (MR) angiography for evaluation of stenosis in the peripheral arterial system with a continuous moving table technique, with conventional MR angiography as reference. This study was approved by the local institutional review board; informed consent was obtained. Five healthy male volunteers (mean age, 27 years; range, 24-35 years) and four men and one woman (mean age, 63 years; range, 46-78 years) with peripheral arterial occlusive disease were examined. Images obtained with both techniques showed excellent concordance (Cohen kappa = 0.75). Images obtained with a conventional protocol had higher quality compared with those obtained with the continuous technique (mean, 1.07 +/- 0.25 [standard deviation] vs 1.58 +/- 0.6; P < .05); small vessels appeared sharper on them. For detection of significant stenosis and occlusion, accuracy, sensitivity, and specificity of the continuous technique were 92.8%, 100%, and 89.2%, respectively.     

Peripheral vascular disease: correlation of MR imaging and angiography

The capability of magnetic resonance (MR) imaging for detecting aortic, iliac, and femoral stenoses and occlusions was evaluated. Multisection spin-echo studies at 0.35 tesla were obtained of the infrarenal aorta to the femoral bifurcation in 24 patients, all of whom had undergone intraarterial angiography within 14 days of imaging. Transaxial MR images were compared with the angiograms. Arterial stenoses and occlusions in these vessels detected by MR imaging correlated with angiographic findings in 91% of the instances. Protrusional atherosclerotic plaques and occlusions and stenoses in the aortoiliac region were demonstrated accurately on MR images; complications of previous vascular surgery, such as aneurysms at sites of previous anastomoses or endarterectomy, were also identified. Due to the limited spatial resolution, MR images failed to demonstrate some femoral stenoses. MR imaging may be used for evaluation of aortoiliac vascular disease and for follow-up study after surgical revascularization. However, the limited spatial resolution, noncomposite display of the aortoiliofemoral circulation, and lack of evaluation of peripheral runoff provided by current MR imaging techniques militate against its replacing angiography prior to vascular intervention.     

Peripheral vascular occlusive disease: evaluation with contrast-enhanced moving-bed MR angiography versus digital subtraction angiography in 106 patients

OBJECTIVE: The purpose of our study was to compare contrast-enhanced moving-bed MR angiography and digital subtraction angiography in the evaluation of peripheral vascular occlusive disease. MATERIALS AND METHODS: This retrospective report includes 106 patients (45 women, 61 men) with known or suspected peripheral vascular occlusive disease who underwent MR angiography and intraarterial digital subtraction angiography of the peripheral arteries. MR angiography was performed on a 1.0-T unit using a moving-bed technique. Every leg was divided into 14 vascular segments, and severity of disease was scored in four categories. Digital subtraction angiography was the standard of reference. RESULTS: In the 106 patients, 2378 vessel segments were evaluated with both imaging modalities. In 2156 segments, MR angiography and digital subtraction angiography were concordant for stenosis classification, in 188 segments the two modalities differed in one category, and in 24 segments they differed in two categories. MR angiography achieved sensitivity and specificity of 96.7% and 95.8%, respectively, for differentiating nonsignificant from hemodynamically significant stenosis (kappa = 0.91). CONCLUSION: This study indicates that MR angiography is an accurate imaging modality in clinical practice. Our data support the concept that MR angiography can modify the diagnosis of suspected peripheral vascular occlusive disease.     

Peripheral vessels: MR angiography with dedicated phased-array coil with large-field-of-view adapter feasibility study

At magnetic resonance (MR) angiography with conventional phased-array coils, visualization of the vascular tree from the infrarenal aorta to the pedal arch is not possible in most patients. For this purpose, the authors developed a dedicated adapter with a large field of view that allows coverage of a body length of approximately 1,380 mm. Among five patients with peripheral arteriosclerotic disease, four underwent both conventional angiography and MR angiography. One hundred fourteen vascular segments from the infrarenal aorta to the feet were evaluated. Agreement between findings at conventional angiography and those at MR angiography was 94.7% (108 of 114) for all segments (96.1% [25 of 26] in the abdomen or pelvis, 97.5% [39 of 40] in the thigh, and 91.7% [44 of 48] in the calf or foot).     

Peripheral arterial disease: gadolinium-enhanced MR angiography versus color-guided duplex US--a meta-analysis

PURPOSE: To summarize and compare the published data on gadolinium-enhanced magnetic resonance (MR) angiography and color-guided duplex ultrasonography (US) for the work-up for peripheral arterial disease. MATERIALS AND METHODS: Studies published between January 1984 and November 1998 were included if (a) gadolinium-enhanced MR angiography and/or color-guided duplex US were performed for evaluation of arterial stenoses and occlusions in the work-up for peripheral arterial disease of the lower extremities, (b) conventional angiography was the reference standard, and (c) absolute numbers of true-positive, false-negative, true-negative, and false-positive results were available or derivable. RESULTS: With a random effects model, pooled sensitivity for MR angiography (97.5% [95% CI: 95.7%, 99.3%]) was higher than that for duplex US (87.6% [95% CI: 84.4%, 90.8%]). Pooled specificities were similar: 96.2% (95% CI: 94.4%, 97.9%) for MR angiography and 94.7% (95% CI: 93.2%, 96.2%) for duplex US. Summary receiver operating characteristic analysis demonstrated better discriminatory power for MR angiography than for duplex US. Regression coefficients for MR angiography versus US were 1.67 (95% CI: -0.23, 3.56) with adjustment for covariates, 2.11 (95% CI: 0.12, 4.09) without such adjustment, and 1.73 (95% CI: 0.44, 3.02) with a random effects model. CONCLUSION: Gadolinium-enhanced MR angiography has better discriminatory power than does color-guided duplex US and is a highly sensitive and specific method, as compared with conventional angiography, for the work-up for peripheral arterial disease.     

Peripheral arterial disease: sensitivity-encoded multiposition MR angiography compared with intraarterial angiography and conventional multiposition MR angiography

A sensitivity-encoded magnetic resonance (MR) angiography protocol was developed in which imaging times in the pelvic and upper-leg positions were reduced and isotropic submillimeter voxel volumes were acquired in the lower-leg position. To achieve this, sensitivity encoding and random central-k-space segmentation in a centric filling order were applied. Results with this technique were compared with those with midstream aortic digital subtraction angiography (DSA) (as the reference standard) and conventional MR angiography in 15 patients with peripheral vascular disease. The results show that sensitivity-encoded MR angiography demonstrates increased diagnostic accuracy in comparison to that with conventional MR angiography and depicts more open infragenual arterial segments compared with both midstream aortic DSA and conventional MR angiography.     

Peripheral arterial occlusive disease: role of MR angiography

PURPOSE: Magnetic resonance angiography (MRA) has recently become instrumental in the diagnosis of arterial disease in various body districts and is gaining an increasingly important role in the study of peripheral vascularisation. The aim of our study was to evaluate the reliability of MRA using digital subtraction angiography (DSA) as the reference standard. MATERIALS AND METHODS: Between November 2003 and August 2004, 30 patients with known peripheral arterial disease were studied by MRA and DSA. MRA was performed with a Philips Intera 1.5 T, with acquisitions from the coeliac trunk to the feet. For acquisitions of the feet and ankles we used unenhanced time-of-flight (TOF) sequences with a head coil. The angiographic sequence was acquired in three volumes of 40-45 cm after administration of paramagnetic contrast material. RESULTS: In the patients with peripheral arterial disease, the technique provided a precise evaluation of the stenosis (mild, moderate, severe) or obstruction of the peripheral district as well as the detection of other diseases, such as stenosis of the renal arteries or aneurysms. CONCLUSIONS: Total-body three-dimensional (3D) MRA allows a fast, safe, and accurate assessment of the arterial system in patients with arteriosclerosis and can be considered an alternative to DSA in the management of patients with steno-obstructive disease of the peripheral arteries.     

Peripheral arterial occlusive disease: P-31 MR spectroscopy of calf muscle

The effect of a graded exercise protocol on phosphorus-31 magnetic resonance (MR) spectroscopy of calf skeletal muscle in nine healthy (control) subjects and 16 patients with symptomatic peripheral arterial occlusive disease (PAOD) was assessed. Ankle-brachial pressure indexes were obtained in all 16 patients, and 10 patients underwent peripheral arteriography. Temporal profiles of pH and the inorganic phosphorus (Pi) index were calculated from the spectra. A Pi-index recovery rate constant was calculated for each subject. Arteriograms were graded by calculating the runoff resistance in the limb of interest. The pH profiles during exercise did not differ significantly between the PAOD patients and control subjects. The Pi-index recovery rate constant in the PAOD patients was significantly (P less than .01) smaller than in the control subjects. There was no significant correlation between recovery rate and the ankle-brachial pressure indexes, but there was a strong negative correlation between recovery rates and angiographic resistance grades, with smaller recovery rate constants in patients with increased arterial resistance. It is concluded that P-31 MR spectroscopy shows promise as a direct measure of tissue perfusion.     

MR angiography for assessment of peripheral vascular disease

Contrast-enhanced 3D MRA is emerging as a powerful noninvasive imaging modality for the assessment of patients with PVD. Its clinical utility using current technology has already been well established, and the continuous development of hard- and software will likely result in significantly improved performance. Thus, Gd-enhanced MRA is likely to emerge as the dominant noninvasive imaging modality for PVD worldwide.     

Prospective blinded evaluation of Gd-DOTA- versus Gd-BOPTA-enhanced peripheral MR angiography,as compared with digital subtraction angiography

PURPOSE: To compare the diagnostic accuracy of gadobenate dimeglumine (Gd-BOPTA)-enhanced versus gadoterate meglumine (Gd-DOTA)-enhanced magnetic resonance (MR) angiography in patients with peripheral arterial occlusive disease (PAOD). MATERIALS AND METHODS: Fifty-six patients underwent MR angiography enhanced with either Gd-DOTA (28 patients) or Gd-BOPTA (28 patients). All arterial segments from the renal arteries to the distal run-off vessels were evaluated for disease severity. The sensitivity, specificity, and accuracy of MR angiography enhanced with both agents separately were evaluated with a paired t test; digital subtraction angiography was the reference standard. Interobserver variability was assessed by using the Cohen test. RESULTS: Diagnostic MR angiograms were obtained in all 56 patients. Overall, sensitivity and specificity of Gd-DOTA-enhanced MR angiography were 96% and 93%, respectively, for observer 1 and 96% and 85%, respectively, for observer 2 (kappa = 0.82). Corresponding values for Gd-BOPTA-enhanced MR angiography were 94% and 93%, respectively, for observer 1 and 94% and 89%, respectively, for observer 2 (kappa = 0.78). No consistent differences between the two contrast materials in assessment of PAOD in the renal to popliteal arteries were observed. For assessment below the knee, specificity was slightly higher in the Gd-BOPTA group-91% and 84% for observers 1 and 2, respectively-than in the Gd-DOTA group-89% and 77%, respectively (P <.01). The number of nonassessable below-the-knee segments was significantly lower in the Gd-BOPTA group: nine of 299 segments versus 25 of 312 segments in the Gd-DOTA group (P <.01). CONCLUSION: At MR angiography of the distal run-off vessels, Gd-BOPTA yielded higher specificity and a significantly smaller number of nonassessable segments than Gd-DOTA. The diagnostic accuracy of the two gadolinium chelates at peripheral MR angiography was comparable in the renal to popliteal arteries.     

Peripheral vascular disease: combined 3D bolus chase and dynamic 2D MR angiography compared with x-ray angiography for treatment planning

PURPOSE: To compare combined three-dimensional (3D) and two-dimensional (2D) contrast material-enhanced magnetic resonance (MR) angiography with x-ray angiography for planning treatment of peripheral vascular disease. MATERIALS AND METHODS: Three radiologists retrospectively reviewed the pretreatment x-ray angiographic and MR angiographic studies obtained in 30 consecutive patients: 15 patients (15 limbs) evaluated for limb salvage and 15 patients (20 limbs) evaluated because of claudication. MR angiography included acquisition of 2D contrast-enhanced MR digital subtraction angiograms of the area from the adductor canal to the feet and 3D spoiled gradient-recalled-echo bolus chase MR angiograms obtained in three stations from the aorta to the middle portion of the calf. Each reader reviewed the x-ray and MR angiograms to determine the inflow and outflow segments for a hypothetical bypass graft placement. RESULTS: The three readers selected identical segments for inflow at MR angiography and x-ray angiography in 32, 32, and 35 of the 35 limbs evaluated (mean percentages of agreement [95% CI ]: 91% [77%, 98%], 91% [77%, 98%], and 95% [90%, 100%], respectively). The readers selected identical segments for outflow in 32, 32, and 34 of the 35 limbs evaluated (mean percentages of agreement [95% CI]: 91% [77%, 98%], 91% [77%, 98%], and 97% [85%, 100%], respectively). CONCLUSION: Preliminary data support the combining of 2D MR digital subtraction angiography with 3D bolus chase MR angiography to extend the utility of 3D MR angiography in treatment planning to include patients being evaluated for limb salvage, as well as those being evaluated for claudication.