Magnetic resonance angiography of the distal lower extremity

Ten-year technical and clinical outcomes in TransAtlantic Inter-Society Consensus II infrainguinal C/D lesions using duplex ultrasound arterial mapping as the sole imaging modality for critical lower limb ischemia

OBJECTIVE

The aim of this study was to evaluate duplex ultrasound arterial mapping (DUAM) as the sole imaging modality when planning for bypass surgery (BS) and endovascular revascularization (EvR) in patients with critical limb ischemia for TransAtlantic Inter-Society Consensus (TASC) II C/D infrainguinal lesions.

METHODS

This was a retrospective review evaluating the accuracy of DUAM as the sole imaging tool in determining patient suitability for BS vs EvR. Primary outcomes were the sensitivity and specificity of DUAM compared with intraoperative digital subtraction angiography. Secondary outcomes were procedural, hemodynamic, and clinical outcomes, amputation-free survival, and freedom from major adverse clinical events.

RESULTS

From 2002 to 2012, a total of 4783 patients with peripheral arterial disease were referred, of whom 622 critical limb ischemia patients underwent revascularization for TASC C and D lesions (EvR: n = 423; BS: n = 199). Seventy-four percent of EvR and 82% of BS were performed for TASC D (P = .218). The DUAM showed sensitivity of 97% and specificity of 98% in identifying lesions requiring intervention. Of the 520 procedures performed with DUAM alone, there was no difference regarding the number of procedures performed for occlusive or de novo lesions (EvR: 65% and 71%; BS: 87% and 78%; P = .056). Immediate clinical improvement to the Rutherford category ≤3 was 96% for EvR and 97% for BS (P = .78). Hemodynamic success was 79% for EvR and 77% for BS (P = .72). Six-year freedom from binary restenosis was 71.6% for EvR and 67.4% for BS (P = .724). Six-year freedom from target lesion revascularization was 81.1% for EvR and 70.3% for BS (P = .3571). Six-year sustained clinical improvement was 79.5% for EvR and 66.7% for BS (P = .294). Six-year amputation-free survival was 77.2% for EvR and 74.6% for BS (P = .837). There was a significant difference in risk of major adverse clinical events between EvR and BS (51% vs 70%; P = .034). Only 16.4% of patients required magnetic resonance angiography, which tended to overestimate lesions with 84% agreement with intraoperative findings. Six-year binary restenosis was 71% for DUAM procedures compared with 55% for magnetic resonance angiography procedures (P = .001), which was solely based on the prospective modality.

CONCLUSIONS

The DUAM epitomizes a minimally invasive, economically proficient modality for road mapping procedural outcome in BS and EvR. It allows for high patient turnover with procedural and clinical success without compromising hemodynamic outcome. The DUAM is superior to other available modalities as the sole preoperative imaging tool in a successful limb salvage program.

From the RSNA Refresher Courses

Acquired diseases of the aorta and peripheral arteries are common. Owing to technical advances, magnetic resonance (MR) angiography has become the primary imaging modality for assessment of aortic and peripheral arterial disease. Contrast material-enhanced MR angiography is a rapid and robust technique that has emerged as the principal MR angiographic technique for evaluation of vascular disease. Two-dimensional time-of-flight MR angiography still has some well-validated applications, especially in distal peripheral vascular disease. Phase-contrast flow imaging is an important technique for quantification of blood flow. Black-blood imaging is a valuable tool for evaluation of the vessel wall. Understanding the principles of the main MR angiographic techniques is essential for consistent acquisition of diagnostic images. In addition, tailoring the acquisition parameters and the imaging protocol to the vessel being imaged and the clinical question is mandatory for optimal results. Future technical developments that will lead to faster image acquisition and better contrast agents promise to further improve image quality.

Electrotherapy reverses inframalleolar ischemia: a retrospective, observational study

OBJECTIVE

To determine if high-voltage pulsed current (HVPC) augments ischemic wound healing and increases periwound perfusion.

DESIGN

A 5-year, retrospective, observational study was conducted on successive patients with ischemic wounds who were poor candidates for revascularization.

INTERVENTION

HVPC was applied directly to wounds at greater than 100 volts, 100 pulses per second, 1 hour per day. In addition to HVPC, patients received standard care for ischemic wounds at the study facility. Ischemic wounds for which HVPC was not clinically indicated or not available received standard care alone.

MAIN OUTCOME MEASURES

Wound area measured by planimetry, wound appearance observed by digital imaging techniques, and microcirculation monitored by transcutaneous oxygen (TcPo(2)) levels.

RESULTS

The group that received HVPC plus standard care showed smaller wound areas from weeks 20 though 52 after the start of treatment compared with the group that received standard care alone (P <.05; Mann-Whitney test). One year after the start of treatment, 90% of HVPC-treated wounds were healed, compared with 29% of the wounds that received only standard care (P <.05; Fisher exact test). For the HVPC group, maximum periwound TcPo(2) improved during electrotherapy (6 +/- 8 mm Hg [standard deviation; SD] at baseline improved to 26 +/- 20 SD, during HVPC, P <.05; Wilcoxon signed rank test).

CONCLUSION

The results of this retrospective trial demonstrate that HVPC plus standard care improved the healing rate of high-risk ischemic wounds. A direct relationship was shown between improved healing rates and increased periwound perfusion. A prospective randomized controlled trial is needed to further support these observational, preliminary findings.

Ankle-arm index versus angiography for the preassessment of the fibula free flap

Peripheral arterial occlusive disease or congenital anomalies of the major crural arteries may limit the use of the fibula free flap and should be detected preoperatively. Conventional selective angiography is the definitive standard imaging method for making this diagnosis, but it has drawbacks. A safer, cheaper, more accurate, and noninvasive alternative is desirable. The authors sought to test the hypothesis that the ankle-arm index of each of the three crural arteries, combined with pencil Doppler examination of the peroneal skin perforators, would provide adequate information to restrict the use of angiography to cases in which the outcomes of either or both of these options are insufficient. The ankle-arm index data of each of the three crural arteries, as well as pencil Doppler examination of the peroneal skin perforators of both legs of nine prospectively included patients and the nonoperated legs of 13 retrospectively included patients, were compared statistically in four different ways with the preoperative angiographic findings. A combined ankle-arm index and pencil Doppler examination is not accurate enough to detect legs or arteries with subclinical peripheral arterial occlusive disease or vascular variation and, hence, is not a sufficient basis on which to develop the surgical plan for a fibula free flap.

Electrotherapy reoxygenates inframalleolar ischemic wounds on diabetic patients: a case series

OBJECTIVE

To retrospectively evaluate the ability of high voltage pulsed current (HVPC) to increase microcirculation in critically ischemic wounds (transcutaneous oxygen [TcPO(2)] less than 10 mm Hg) and, as a result, to improve wound healing.

DESIGN AND METHODS

Clinical case series with successive adult diabetic subjects (3 men and 3 women) with nonsurgical ischemic malleolar or inframalleolar skin lesions, each subject serving as his or her own control. Wound area and TcPO(2) were measured periodically. Presence of distal arteriosclerosis was assessed on 5 patients by 2-dimensional, time-of-flight magnetic resonance angiography. End point was either complete wound closure or leg amputation.

RESULTS

Maximum mean TcPO(2) was 2 +/- 2 mm Hg at the wound edge before the start of electrotherapy. After electrotherapy began, maximum TcPO(2) was 33 +/- 18 mm Hg (N=6; P<.05, Wilcoxon signed rank test). After treatment with HVPC, 4 patients' wounds healed and 2 patients underwent amputation. As expected, healed patients initially deteriorated after the start of treatment, but their wounds began healing when the perilesion TcPO(2) measurement exceeded 20 mm Hg. Thereafter, the wounds closed at a predictable rate. Complete closure occurred for patients who had a relatively low atherosclerotic burden.

CONCLUSION

The results of this clinical case series suggest that electrotherapy can improve periwound microcirculation of ischemic inframalleolar skin lesions.

Contrast enhanced MR angiography in the assessment of relevant stenoses in occlusive disease of the pelvic and lower limb arteries: diagnostic value of a two-step examination protocol in comparison to conventional DSA

INTRODUCTION/OBJECTIVES

Contrast-enhanced MRA (ce-MRA) has been claimed by many authors as a replacement of conventional angiography evaluating peripheral arterial occlusive disease. However, reliable detection of relevant stenoses (>70%) has to be provided for planning vascular interventions. Only few data in the literature focuses on this crucial problem. The purpose of this study was to evaluate this topic using a two-step body-coil-based MRA protocol.

METHODS AND PATIENTS

Forty three patients presenting with 82 stenoses >/=50% and 61 stenoses >70% on conventional catheter angiogram received fast Gadolinium-DTPA-enhanced high resolution 3D MR angiography at 1.5 T covering the pelvic and peripheral vascular tree in two examination steps using the body-coil. The data were evaluated double-blinded by three readers distinguishing moderate (50-70%) from severe stenoses (>70%).

RESULTS

Overall sensitivity/specificity/accuracy was 84/60/70% evaluating 143 segments. Specificity was rather poor in the iliac (58%) and crural (50%) region and moderate in the femoral and popliteal level (73%). The negative predictive value ranged between 78 and 91%. The grade of stenosis tend to be overestimated rather than underestimated in all levels with positive predictive values between 55 and 78%.

DISCUSSIONS AND CONCLUSIONS

Body-coil-based contrast-enhanced MRA has limited potential in distinguishing moderate from severe stenoses in peripheral occlusive disease. Overestimations are more common than underestimations. Both occur mainly in small-sized crural arteries but also in larger iliac arteries where vessel course in partition direction may cause inadequacy between voxel size and lumen diameter in severe stenosis.

Peripheral vascular surgery and magnetic resonance arteriography--a review

OBJECTIVES

to review the current status of lower limb MRA.

DESIGN

a literature review based predominantly on a MEDLINE database search of English-language publications from January 1991 to October 2000.

MATERIALS AND METHODS

twenty-eight articles, concerning non-enhanced MRA (13), gadolinium-enhanced MRA (14) or both (1), met the predefined requirement for quality. Results gadolinium-enhanced MRA (CE-MRA) seems to be more accurate, quicker and associated with fewer problems than non-enhanced (TOF) MRA. TOF-MRA has a sensitivity and specificity of 93% (range 64-100%) and 88% (range 57-100%) respectively, and CE-MRA presents values of 96% (range 71-100%) and 96% (63-100%), respectively, using conventional arteriography as the gold standard. Some articles report a substantial incidence of runoff vessels suitable for distal bypass visible on MRA but invisible on conventional arteriography. Gadolinium contrast is given intravenously and is generally well tolerated and has no known nephrotoxicity.

CONCLUSION

CE-MRA is accurate compared to conventional arteriography, has the potential to increase the limb salvage rate for selected patients, is non-invasive and well tolerated.

Dynamic contrast-enhanced MR angiography from the distal aorta to the ankle joint with a step-by-step technique

OBJECTIVE

The aim of this study was to visualize the arteries from the distal aorta to the ankle joint and to determine the accuracy of MR angiography for detecting stenoses and occlusions.

SUBJECTS AND METHODS

Twenty-four patients with peripheral arterial occlusive disease underwent digital subtraction angiography and were examined on a 1.5-T MR scanner. The transit time for contrast material was determined with a test bolus injection. A T1-weighted three-dimensional gradient-echo sequence with short TR and TE was used for a dynamic measurement at the level of the iliac arteries, the upper leg, and the lower leg arteries. For each level a single dose of gadolinium was injected into an antecubital vein with an MR power injector. Maximal-intensity-projection reconstructions were calculated after subtraction of the first measurement at each level. Two experienced MR radiologists who were unaware of the digital subtraction angiography results interactively evaluated both the MIP reconstructions and the single slices on a workstation, first independently and then in a consensus interpretation.

RESULTS

With digital subtraction angiography, 80 hemodynamically significant stenoses and 39 occlusions were detected. For the stenoses and occlusions, a sensitivity of 100% was found for MR angiography. The specificity for the assessment of stenoses and occlusions was 98% and 94%, respectively, for the iliac arteries; 98% and 94%, respectively, for the upper leg arteries; and 94% and 95%, respectively, for the lower leg arteries. Most false-positive findings of occlusion were due to metal stents present in the iliac (n = 3) and upper leg (n = 4) arteries.

CONCLUSION

The MR imaging technique that we used revealed the arteries from the distal aorta to the ankle and proved to be reliable at showing arterial stenoses and occlusions.

Peripheral arterial disease: meta-analysis of the diagnostic performance of MR angiography

PURPOSE

To summarize the overall diagnostic performance of magnetic resonance (MR) angiography in the evaluation of peripheral arteriosclerotic occlusive disease and to identify the most important sources of variation in diagnostic accuracy between studies.

MATERIALS AND METHODS

A search strategy in MEDLINE and citation tracking were used to identify relevant English-language articles published since 1991. Each article was critically appraised for examination, patient, and study design characteristics. The accuracy data from different studies were analyzed by constructing summary receiver operating characteristic curves; multiple linear regression was used to examine the variation between study results.

RESULTS

Twenty-three studies were included. There was much heterogeneity in the study results, which could not be explained as differences in the threshold for a positive result. About half of the variation was due to the type of MR angiographic examination and the extent of image evaluation. The relative diagnostic odds ratio (DOR) for three-dimensional (3D) gadolinium-enhanced MR angiography compared with two-dimensional (2D) time-of-flight MR angiography was 7.46 (95% CI: 2.48, 22.20). The relative DOR for review of transverse source images or multiplanar reformations in addition to maximum intensity projections (MIPs) compared with the use of only MIPs for image evaluation was 4.53 (95% CI: 1.46, 13.87).

CONCLUSION

The diagnostic accuracy of 3D gadolinium-enhanced MR angiography is superior to that of 2D time-of-flight MR angiography. Also, the review of transverse source images or use of additional postprocessing techniques, such as multiplanar reformation, results in significantly better diagnostic performance.

Comparison of treatment plans for lower extremity arterial occlusive disease made with electrocardiography-triggered two-dimensional time-of-flight magnetic resonance angiography and digital subtraction angiography

BACKGROUND

The purpose of the study was to determine whether preoperative treatment plans for patients with lower extremity ischemia can be made with electrocardiography (EKG)-triggered two-dimensional (2D) time-of-flight (TOF) magnetic resonance angiography (MRA) as accurately as digital subtraction angiography (DSA).

METHODS

Forty patients were prospectively evaluated with the combination of EKG-triggered 2D TOF MRA, DSA, and pulse volume recordings. Blinded reviewers graded arterial segments for disease severity. Accuracy of separate MRA- and DSA-based treatment plans was compared with the procedures performed based on all available information.

RESULTS

There was an 86% exact match between MRA- and DSA-based plans (92% MRA and 94% DSA accuracy). The MRA-based plan accurately predicted 90% of suprainguinal and 95% of infrainguinal procedures, whereas the DSA-based plan accurately predicted 100% of suprainguinal and 85% of infrainguinal procedures. Two-year primary patency was 83% for all procedures. Radiologists' review of disease severity resulted in a mean exact correlation between studies of 81% (kappa = 0.64). The agreement between radiologists interpreting the MRA was 84% (kappa = 0.7) compared with 82% (kappa = 0.66) for the DSA.

CONCLUSIONS

MRA- and DSA-based preoperative management plans were of comparable efficacy. Significant interobserver variability was seen with the interpretations of both preoperative studies. EKG-triggered 2D TOF MRA can be used to plan arterial reconstructions; however, all patients require arterial pressure measurements prior to suprainguinal repair and confirmatory intraoperative angiography during infrainguinal revascularization.

Stepping-table gadolinium-enhanced digital subtraction MR angiography of the aorta and lower extremity arteries: preliminary experience

PURPOSE

To compare stepping-table digital subtraction gadolinium-enhanced magnetic resonance (MR) angiography of the distal aorta and lower extremity arteries with conventional catheter digital subtraction x-ray angiography in patients with arterio-occlusive disease.

MATERIALS AND METHODS

Twenty patients underwent both conventional catheter angiography and fast three-dimensional gadolinium-enhanced MR angiography of the aorta and outflow vessels at 1.5 T; the images were acquired in three consecutive imaging locations during a single infusion of a gadolinium chelate.

RESULTS

Compared with catheter angiography, according to the findings of two blinded independent reviewers, MR angiography had sensitivities of 81% and 89% and specificities of 91% and 95%, respectively, for demonstration of insignificant (< or = 50%) stenosis versus significant (51%-100%) stenosis. For demonstration of occlusion, the sensitivity and specificity were 94% and 97%, respectively, by consensus. There was good interobserver correlation between the two readers overall (kappa = 0.65 for reporting the degree of narrowing in all lesions; 0.86, for reporting of insignificant versus significant stenoses; and 0.928, for reporting of occluded versus patient segments).

CONCLUSION

Stepping-table digital subtraction contrast material-enhanced MR angiography has high accuracy compared with catheter angiography in patients with arterio-occlusive disease of the aorta and outflow vessels. These preliminary study results suggest that this technique may ultimately provide a safe, noninvasive, and cost-effective alternative to catheter angiography.

Lower extremity occlusive disease: diagnostic imaging with a combination of cardiac-gated 2D phase-contrast and cardiac-gated 2D time-of-flight MRA

PURPOSE

The goal of this work was to test the ability of a combination of 2D phase-contrast MR angiography (2D-PC-MRA) and triggered 2D time-of-flight MRA (2D-TOF-MRA) in comparison to intraarterial digital subtraction angiography (DSA) to correctly diagnose the location and shape of occlusive lesions in the iliac and femoral arteries and to determine whether 2D-TOF-MRA is helpful to clarify questionable lesions demonstrated by 2D-PC-MRA.

METHODS

In 50 patients with claudication, 2D-PC-MRA was performed in three consecutive coronal positions from the aortic bifurcation to below the trifurcation. Axial 2D-TOF-MRA was performed additionally at the site of detected lesions of >50% and lesions in doubt to obtain more precise information about the stenosis. Lesions were classified as follows: low grade occlusion, <50%; high grade occlusion, >50%. MRA was performed within 24 h of a DSA examination.

RESULTS

In all patients, the arterial tree from the aortic bifurcation to the trifurcation could be visualized. One hundred twelve lesions were detected by MRA. Sensitivity was 96% and specificity was 92%. Sixty-two lesions were classified as high grade occlusion and reevaluated. In this category, sensitivity was 100% and specificity was 96%.

CONCLUSION

The combination of 2D-PC-MRA with triggered 2D-TOF-MRA detects stenotic lesions in the lower extremity arterial system with high sensitivity and specificity.

Comparison of two-dimensional MR digital subtraction angiography of the lower extremity with x-ray angiography

PURPOSE

To perform a preliminary evaluation of the diagnostic accuracy of contrast-enhanced, two-dimensional (2D) magnetic resonance (MR) digital subtraction angiography (DSA) of the lower extremity by comparison with x-ray angiography (XRA).

MATERIALS AND METHODS

Forty lower extremities in 22 patients were imaged at multiple levels with both XRA and 2D MR DSA. Images were retrospectively analyzed by three radiologists in a randomized blinded manner. Seventeen vascular segments were graded as an insignificant lesion, a significant lesion, or as an occlusion. With the use of segments well depicted with XRA as the gold standard, the sensitivity, specificity, and accuracy of 2D MR DSA, as compared with XRA, were evaluated. The McNemar-Stuart-Maxwell test was performed to determine the significance of any differences found.

RESULTS

Three hundred eighty-three arterial segments were evaluated with both techniques. Three hundred one segments were well depicted with XRA. There was no significant difference between 2D MR DSA and XRA for assessing the degree of occlusive disease in these 301 segments (.25 < P < .5). The sensitivity, specificity, and diagnostic accuracy of 2D MR DSA were found to be 90%, 98%, and 93%, respectively.

CONCLUSION

Two-dimensional MR DSA is an accurate method for assessing arterial lesions in the lower extremity.

A phase contrast (PC) rephase/dephase sequence of magnetic resonance angiography (MRA): a new technique for imaging distal run-off in the pre-operative evaluation of peripheral vascular disease

OBJECTIVE

To prospectively compare a 3-D phase contrast (PC) magnetic resonance angiography (MRA) sequence (rephase/dephase) with digital subtraction angiography (DSA) in pre-operative evaluation for femoropopliteal grafting in peripheral vascular disease. Assessment of distal run-off vessels and suggested siting of distal graft anastomosis to the above or below knee segment of the popliteal artery was made.

METHODS

Twenty-two lower extremities booked for infra-inguinal vascular reconstruction were imaged pre-operatively using MRA and DSA. A PC rephase/dephase sequence which includes gradient motion refocusing (Siemens 1.0 T Magnetom Impact TR 50 ms, TE 14/14 ms and 15 degree flip angle) and 3-D MIP algorithm reconstruction was used to obtain the MR images. Standard techniques were used to obtain the DSA images, and the mean and median time between imaging modalities was one month. Blinded review by a consultant vascular radiologist scored nine vessel segments for each limb and assessed which popliteal arterial segment would be most suitable for distal anastomosis.

RESULTS

The score from DSA and MRA agreed for 155/198 vessel segments (kappa 0.57) and the suggested siting for distal anastomosis agreed for 19/22 limbs (kappa 0.72). Eighteen limbs had surgery as planned (distal anastomosis to the above knee popliteal eight limbs, below knee popliteal 10 limbs). For three limbs the siting of the distal anastomosis suggested by DSA and MRA disagreed. The more accurate modality was proved for one of three limbs and showed MRA to be superior to DSA.

CONCLUSION

Three-dimensional PC rephase/dephase MRA is a promising technique which compared well with DSA in the pre-operative assessment of distal run-off for femoropopliteal grafting.

Donor site evaluation for fibula free flap transfer

PURPOSE

The role of routine preoperative angiography in patients undergoing fibula flap transfer remains controversial. A recent survey of experienced microvascular surgeons indicated that routine angiography may be unnecessary in patients with no symptoms of peripheral vascular disease and normal lower extremity pulses. To study the necessity of performing preoperative vascular imaging studies, the incidence of congenital and acquired vascular anomalies that prevented the harvest of a fibula flap is reported in a series of patients undergoing evaluation for oromandibular reconstruction

PATIENTS AND METHODS

A series of 19 consecutive patients who underwent preoperative lower extremity vascular imaging studies in anticipation of performing a fibula free flap is presented.

RESULTS

Angiographic findings significantly altered the surgical reconstruction that was performed in 4 of 19 (21%) patients. Three patients with a history or examination suggestive of peripheral vascular disease were excluded on the basis of the findings at the time of radiographic study. In a fourth patient, the contralateral leg was used for reconstruction when preoperative angiography showed a dominant peroneal artery supplying the foot in the extremity initially considered for flap harvest.

CONCLUSION

History and physical examination are not helpful in detecting most congenital vascular anomalies that would place the foot at risk for ischemia if the peroneal artery is sacrificed. The findings of this small series are consistent with the previously documented incidence of anomalous blood supply to the foot and demonstrate the need for preoperative vascular imaging studies in patients undergoing fibula free flap transfer to avoid a potentially catastrophic complication.

Utility of magnetic resonance arteriography for distal lower extremity revascularization

PURPOSE

Magnetic resonance arteriography (MRA) of the lower extremities affords several possible advantages over conventional contrast arteriography (CA). We hypothesized that MRA of the infrageniculate vessels was sufficiently accurate to replace CA before revascularization procedures in patients with limb-threatening ischemia.

METHODS

Fifty-three extremities in 49 patients were prospectively evaluated before attempted infrageniculate revascularization procedures with preoperative infrageniculate time-of-flight MRA (cost, $170/study) and standard contrast arteriography (cost, $1310/study) of the aortoiliac and runoff vessels. Independent operative plans were formulated based on the MRA and CA results before the revascularization procedure. Intraoperative, prebypass arteriograms (IOA; cost, $46/study) were obtained in all patients to confirm the adequacy of the distal runoff. The preoperative plans formulated by the results of MRA and CA were compared with the actual procedure performed based on the IOA. All arteriograms (CA, MRA, IOA) were reviewed after the operation by two independent reviewers, and the number of patent vessel segments and those with < 50% stenosis was determined.

RESULTS

Revascularization procedures were performed in 44 of 53 extremities (83%), and amputation was performed in nine extremities (17%) because of an absence of a suitable bypass target. The CA and MRA were equally effective in predicting the optimal operative plans as determined from IOA (CA, 42 of 53 [77%] vs MRA, 40 of 53 [75%]; p = 0.79). More patent vessel segments were seen on CA than MRA (reviewer A, 229 vs 174, kappa = 0.32; reviewer B, 321 vs 314, kappa = 0.46); however, a comparable number of segments were seen if the vessels of the foot were excluded. The accuracy (reviewer A, 78% vs 68%, p = 0.003; reviewer B, 75% vs 67%, p = 0.003) and sensitivity (reviewer A, 69% vs 51%, p = 0.001; reviewer B, 68% vs 46%, p = 0.0001) of CA relative to IOA were superior to those of MRA, although the specificity was comparable (reviewer A, 86% vs 90%, p = 0.31; reviewer B, 82% vs 87%, p = 0.52). The combination of MRA and IOA would have resulted in the optimal operative plan in 51 of the 53 cases (96%) and was comparable with CA and IOA (53 of 53; 100%; p = 0.50). Substitution of MRA and IOA for CA and IOA could potentially have saved an estimated $60,420.

CONCLUSIONS

The combination of MRA and IOA provides an accurate, cost-efficient strategy for visualization of the infrageniculate vessels before revascularization procedures.

Three-dimensional flow-independent peripheral angiography

A magnetization-prepared sequence, T2-Prep-IR, exploits T1, T2, and chemical shift differences to suppress background tissues relative to arterial blood. The resulting flow-independent angiograms depict vessels with any orientation and flow velocity. No extrinsic contrast agent is required. Muscle is the dominant source of background signal in normal volunteers. However, long-T2 deep venous blood and nonvascular fluids such as edema also contribute background signal in some patients. Three sets of imaging parameters are described to address patient-specific contrast requirements. A rapid, spiral-based, three-dimensional readout is utilized to generate high-resolution angiograms of the lower extremities. Comparisons with x-ray angiography and two-dimensional time-of-flight angiography indicate that this flow-independent technique has unique capabilities to accurately depict stenoses and to visualize slow flow and in-plane vessels.