Endovascular surgery based solely on noninvasive preprocedural imaging

Arterial Duplex Ultrasound is the Most Cost-Effective, Noninvasive Diagnostic Imaging Modality before Treatment of Lower-Extremity Arterial Occlusive Disease

Introduction

Multiple noninvasive imaging modalities (duplex ultrasound, magnetic resonance angiography, and computed tomographic angiography) are now available for diagnostic evaluation of lower-extremity arterial occlusive disease (LEOD). This study was performed to determine the effectiveness of duplex ultrasound as the primary diagnostic imaging test before endovascular treatment and to estimate the potential cost-savings compared with the use of other technologies.

Methods

The diagnostic evaluations of all patients treated for LEOD by a single vascular specialist between July 2004 and February 2008 were reviewed. The medical records were reviewed for the initial noninvasive diagnostic imaging study, type of intervention, and patency of revascularization. Medicare reimbursement rates (2007) for each imaging modality were used to compare costs of diagnostic testing.

Results

A total of 128 endovascular interventions were performed in 89 patients. Arterial duplex imaging was the primary and only diagnostic study performed prior to endovascular treatment in 108 (84%) of procedures. If preintervention magnetic resonance angiography or computed tomographic angiography had been used in these patients instead of duplex, the costs for diagnostic imaging alone would have increased by $96,064 and $44,762, respectively.

Conclusion

Arterial duplex ultrasound can be effectively used as the preferred modality for noninvasive imaging of LEOD, resulting in substantial cost savings.

Selection of Patients with Lower Limb Arterial Occlusive Disease for Endovascular Treatment of the Iliac Arteries with Duplex Scanning

The aim of this study was to evaluate the role of duplex scanning in selection of patients with lower limb arterial occlusive disease for endovascular treatment of the iliac arteries. From January 1995 through May 2000, 183 patients having chronic lower limb arterial insufficiency who underwent duplex scanning of the lower extremity arteries with available aortoiliac scans within 3 months before conventional aortoiliac diagnostic angiography and/or endovascular intervention of the iliac arteries were studied retrospectively. The findings obtained from duplex scanning and angiography were analyzed in a blinded manner by 2 investigators. Limbs having category 1, 2, and 3 lesions according to duplex scan findings were interpreted as being suitable for endovascular intervention. The comparison between duplex scan findings and angiography was analyzed by the third investigator.

During 93 percutaneous transluminal angioplasty (PTA) procedures, 133 arterial segments, common or external iliac, were dilated with stent placement in 70. Bilateral interventions were performed in 25 cases, and of 68 unilateral interventions, 57 were at only 1 arterial segment. The accuracy, sensitivity, specificity, and negative and positive predictive values of duplex scanning to appropriately categorize the iliac artery lesions into suitable or unsuitable for endovascular intervention were 90%, 95%, 83%, 90%, and 92%, respectively when the inconclusive duplex scans were excluded (11%). In 6 patients with lesions suitable for PTA according to duplex scanning and angiography, PTA was not performed owing to clinical reasons. The accuracy of duplex scanning in predicting the performance of endovascular intervention was 88%.

It is concluded that iliac artery endovascular procedures in limbs with chronic occlusive disease can be reliably planned according to duplex scan findings.

Duplex ultrasound scanning of peripheral arterial disease of the lower limb

OBJECTIVES

To assess the reliability and applicability of duplex ultrasound scanning (DUS) of lower limb arteries, compared with digital subtraction angiography (DSA), in patients with peripheral arterial disease (PAD).

DESIGN

A prospective, blinded, comparative study.

MATERIALS AND METHODS

A total of 169 patients were examined by DUS and DSA. Intermittent claudication (IC) was present in 42 (25%) patients and critical limb ischaemia (CLI) in 127 (75%) patients. To allow segment-to-segment comparison, the arterial tree was divided into 15 segments. In total, 2535 segments were examined using kappa (κ) statistics to test the agreement.

RESULTS

The agreement between DUS and DSA was very good (κ>0.8) or good (0.8 ≥ κ>0.6) in most segments, but moderate (0.6 ≥ κ>0.4) in the tibio-peroneal trunk and the peroneal artery. Agreement between the two techniques was significantly better in the supragenicular (κ=0.75 (95% confidence interval (CI): 0.70-0.80)) than in the infragenicular segments (κ=0.63 (0.59-0.67)) (p<0.001). Similarly, the technical success rate was significantly higher in the supragenicular segments (DUS: 100%; DSA: 99%) than in the infragenicular segments (both 93%) (p<0.001). DUS was the best technique for imaging of the distal crural arteries (92% vs. 97%; p<0.001) and DSA was the best technique for imaging of the proximal crural arteries (95% vs. 91%; p<0.01). Neither the agreement nor the technical success rate was influenced by the severity of PAD, that is, IC versus CLI.

CONCLUSION

The agreement between DUS and DSA was generally good, irrespective of the severity of ischaemia. DUS performed better in the supragenicular arteries than in the infragenicular arteries. However, DUS compared favourably with DSA in both tibial vessels, particularly in the distal part, which makes DUS a useful non-invasive alternative to DSA.

Does Medicare Have an Implicit Cost-Effectiveness Threshold?

Background. Despite the huge cost of the program, the Centers for Medicare and Medicaid Services (CMS) has maintained a policy that cost-effectiveness is not considered in national coverage determinations (NCDs). Objective. To assess whether an implicit cost-effectiveness threshold exists and to determine if economic evidence has been considered in previous NCDs. Methods. A literature search was conducted to identify estimates of cost-effectiveness relevant to each NCD from 1999—2007 (n = 103). The economic evaluation that best represented each coverage decision was included in a review of the cost-effectiveness of medical interventions considered in NCDs. Results. Of the 64 coverage decisions determined to have a corresponding cost-effectiveness estimate, 49 were associated with a positive coverage decision and 15 with a noncoverage decision. Of the positive decisions, 20 were associated with an economic evaluation that estimated the intervention to be dominant (costs less and was more effective than the alternative), 12 with an incremental cost-effectiveness ratio (ICER) of less than $50,000, 8 with an ICER greater than $50,000 but less than $100,000, and 9 with an ICER greater than $100,000. Fourteen of the sample of 64 decision memos cited or discussed cost-effectiveness information. Conclusions. CMS is covering a number of interventions that do not appear to be cost-effective, suggesting that resources could be allocated more efficiently. Although the authors identified several instances where cost-effectiveness evidence was cited in NCDs, they found no clear evidence of an implicit threshold.

Limitations of and Lessons Learned from Clinical Experience of 1,020 Duplex Arteriography

Objective: Due to the inherent risks, deficiencies and cost associated with contrast arteriography (CA), our group has been utitilizing duplex arteriography (DA) for evaluating the arteries of the lower extremity for patients undergoing lower extremity revascularization. In an effort to further explore the strengths and weaknesses of DA, we reviewed our evolving experience with DA from January 1, 1998, to January 1, 2005.

Patients and Methods: The arterial segments starting from mid-abdominal aorta to the pedal arteries were studied in cross-sectional and longitudinal planes using a variety of scanheads of 7–4, 10–5, 12–5, 5–2 and 3–2 MHz extended operative frequency range to obtain high-quality B-mode, color and power Doppler images as well as velocity spectra. In 906 patients, 1,020 duplex arteriograms were obtained. The ages ranged from 30–98 years old with a mean of 73±11 (SD) years. Fifty percent of the patients were diabetics. Indications for the examination included: tissue loss (409), rest pain (221), claudication (310), acute ischemia (74), popliteal aneurysm (45), SFA aneurysm (2), abdominal aortic aneurysms (AAA) (10) and failing bypass (55). Prior procedures had been performed in 262. DA was performed by six technologists (4 of whom are MDs). In all, 207 DA were performed intraoperatively and the remainder, preoperatively.

Results: The resultant procedures based upon DA included: bypass to the popliteal artery (262) and bypass to an infrapopliteal artery (325), endovascular procedures (363), thrombectomy (11), embolectomy (9), inflow bypass procedures to the femoral arteries (46), débridment (4), amputation (8) and no intervention (75). The areas not visualized well included: iliac (73), femoral (26), popliteal (17), and infrapopliteal (221). Additional imaging after DA was deemed necessary in 102 cases to obtain enough information to plan lower extremity revascularization. Factors associated with increased need to obtain CA included: DM ( p<.001), infrapopliteal calcification ( p<.001), older age ( p = .01) and limb threatening ischemia ( p<.001). Factors not associated with the need to obtain CA included: which technologist performed the exam, whether the technologist has a medical degree and whether the patient underwent prior revascularization.

Conclusions: In 90% of patients reviewed, DA is able to obtain the needed information to plan lower extremity revascularization. Severe tibial vessel calcification is the most common cause of an incomplete DA exam and determines when alternative imaging modalities need to be obtained.

Cost-effectiveness of identifying aortoiliac and femoropopliteal arterial disease with angiography or duplex scanning

OBJECTIVES

Cost-effectiveness analysis of three diagnostic imaging strategies for the assessment of aortoiliac and femoropopliteal arteries in patients with peripheral arterial occlusive disease. The strategies were: angiography as the reference strategy, duplex scanning (DS) plus supplementary angiography (S1) and DS plus confirmative angiography (S2).

DESIGN, MATERIALS AND METHODS

A decision model was built with sensitivity and specificity data from literature, supplemented with prospective hospital cost data in Euro (euro). The probability of correctly identifying the status of a lesion was taken as the primary outcome. We compared strategies by assessing the extra costs per additional correctly identified case.

RESULTS

Assuming no false positive or false negative results, angiography is the most effective strategy if the prevalence of significant obstructive lesions in the aortoiliac and femoropopliteal tract exceeds 70%, or if the sensitivity of duplex scanning is lower than 83%. In case of lower prevalence, strategy S1 becomes equally or even more effective than angiography. At a prevalence of 75%, performing angiography costs euro 8443 per extra correctly identified case compared with strategy S1.

CONCLUSIONS

In most situations angiography is more effective than diagnostic strategy S1. However, if society is unwilling to pay more than euro 8443 for knowing a patient's disease status, diagnostic strategy S1 is a cost-effective alternative to angiography, especially at lower prevalence values.

A Prospective Feasibility Study of Duplex Ultrasound Arterial Mapping, Digital-Subtraction Angiography, and Magnetic Resonance Angiography in Management of Critical Lower Limb Ischemia by Endovascular Revascularization

Duplex ultrasound arterial mapping (DUAM) allows precise evaluation of peripheral vascular disease (PVD). However, magnetic resonance angiography (MRA) and digital-subtraction angiography (DSA) are the diagnostic tools used most frequently prior to intervention. Our aim was to compare clinical pragmatism, hemodynamic outcomes, and cost-effectiveness when using DUAM alone compared to DSA or MRA as preoperative assessment tools for endovascular revascularization (EvR) in critical lower limb ischemia (CLI). From 2002 through 2005, 465 patients were referred with PVD. Of these, 199 had CLI and 137 required EvR. Preoperative diagnostic evaluation included DUAM (n = 41), DSA (n = 50), or MRA (n = 46). EvR was aortoiliac in 27% of cases and infrainguinal in 73%. Patients were assessed at day 1, 6 weeks, 3 months, and 6 months. Composite end points were relief of rest pain, ulcer/gangrene healing, and increase in perfusion pressure, as measured by ankle-brachial index (ABI) and digital pressures. Patency by DUAM, limb salvage, morbidity, mortality, length of stay, and cost-effectiveness were compared between groups using nonparametric t-test, analysis of variance, and Kaplan-Meier analysis. The three groups were comparable in terms of age, sex, comorbidity, and Society for Vascular Surgery/International Society of Cardiovascular Surgery clinical classification. Six-month mean improvement in ABI in the DUAM group was comparable to that in the DSA group (P = 0.25) and significantly better than that in the MRA group (P < 0.05). Six-month patency rates for the DUAM group were comparable to those in the DSA group (P = 0.68, relative risk [RR] = 0.74, 95% confidence interval [CI] 0.18-2.99) and superior to that in the MRA group (P = 0.022, RR = 0.255, 95% CI 0.09-0.71). Length of hospital stay was lower in the DUAM group compared with the DSA group (P < 0.0001) and the MRA group (P = 0.0003). The cost of DUAM is lower than that of both DSA and MRA. DUAM accurately identified the total number of target lesions for revascularization; however, MRA overestimated it. Our results indicate that DUAM is outstanding when compared with other available modalities as a preoperative imaging tool in a successful EvR program. DUAM is a minimally invasive preoperative evaluation for EvR and offers precise consecutive data with patency and limb salvage rates comparable to EvR based on DSA and superior to MRA. We believe that our feasibility study has established DUAM as an economically proficient primary modality for investigating patients with CLI that significantly shortens length of hospital stay.

Preprocedural imaging: new options to reduce need for contrast angiography

In vascular surgery, the gold standard for evaluation of the lower-extremity arterial tree has long been contrast arteriography (CA). Associated risks of CA are well-documented and include severe allergic reactions, arterial injury and/or hemorrhage, and contrast-induced nephropathy. Increasingly, less-invasive techniques, with fewer inherent risks for complication, are being explored as diagnostic alternatives. Magnetic resonance angiography, computed tomography angiography, and duplex arteriography, each offer distinct advantages, though are not without limitation. This review explores the indications, advantages, and disadvantages of these newer technologies and provides a comparison to CA as a means for defining the anatomic features of patients undergoing lower-extremity revascularization. This data suggests that noninvasive imaging technologies may, in the future, play an increasingly important role in the surgical evaluation of the patient with lower-extremity ischemia.

Magnetic resonance angiography versus duplex arteriography in patients undergoing lower extremity revascularization: which is the best replacement for contrast arteriography?

OBJECTIVE

In an effort to explore alternatives to contrast material-enhanced arteriography, we compared magnetic resonance angiography (MRA) and duplex arteriography (DA) with contrast arteriography (CA) for defining anatomic features in patients undergoing lower extremity revascularization.

METHODS

From August 1, 2001, to August 1, 2002, 61 consecutive inpatients (64 limbs) with chronic lower extremity ischemia underwent CA, MRA, and DA before undergoing lower extremity revascularization procedures. The reports of these tests and images were compared prospectively, and the differences in the iliac, femoropopliteal, and infrapopliteal segments were noted. The vessels were classified as mildly diseased (<50%), moderately diseased (50%-70%), severely diseased (71%-99%), or occluded. The studies and treatment plans based on these data were compared.

RESULTS

Mean patient age was 76 +/- 10 years (SD). Indications for the procedures included gangrene (43%), ischemic ulcer (28%), rest pain (19%), severe claudication (9%), and failing bypass (1%). During this period 35 patients were ineligible for the protocol, because they could not undergo MRA (n=27) or angiography (n=8). Of the total 192 segments in the 64 patients (iliac, femoropopliteal, tibial), 17% were not able to be fully assessed with DA, and 7% with MRA. Disagreements with CA and DA were found in the iliac, femoropopliteal, and tibial segments in 0%, 7%, and 14% of cases, respectively, and between CA and MRA in 10%, 26%, and 42% of cases, respectively. Two of 9 differences (22%) between DA and CA were thought to be clinically significant, and 28 of 45 differences (62%) between MRA and CA were thought to be clinically significant.

CONCLUSIONS

A review of the data obtained in this series indicates that MRA does not yet seem to yield adequate data, at least in this highly selected population at our institution. When severe calcification is identified, CA may be necessary in patients undergoing DA.

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.

Gadolinium-enhanced MR Angiography as First-Line Preoperative Imaging in High-Risk Patients with Lower Limb Ischemia

PURPOSE

To assess the clinical relevance of gadolinium-enhanced MR angiography (Gd-MRA) as the first-line angiographic examination for planning lower limb revascularization in patients at high risk of complications after contrast arteriography (CA).

METHOD

Forty-five consecutive patients at high risk of post-CA complications because of chronic renal insufficiency, diabetes mellitus, advanced age, or the need for brachial artery catheterization or graft puncture had Gd-MRA as first-line angiography before a surgical or endovascular procedure for lower limb ischemia.

RESULTS

After Gd-MRA, 59 procedures were performed, including 38 surgical reconstructions, 17 endovascular procedures, and four amputations. Complementary CA was only required in seven patients for whom a below-knee bypass was planned. Cumulative patency rates at 1 and 24 months were, respectively, 91% and 91% for suprainguinal bypasses, 100% and 92% for infrainguinal above-knee bypasses, 80% and 57% for below-knee bypasses, and 92% and 76% for iliofemoral angioplasties. After 24 months of follow-up, limb salvage, amputation, and mortality rates were, respectively, 86%, 3.5%, and 7% for stage II ischemia and 48%, 11%, and 30% for stages III and IV.

CONCLUSION

Gd-MRA can be proposed for first-line preoperative imaging in the management of lower limb ischemia for patients at high risk and permits the selective use of CA as a second-line examination if a below-knee bypass is required.

Contrast Material–enhanced, Moving-Table MR Angiography versus Digital Subtraction Angiography for Surveillance of Peripheral Arterial Bypass Grafts

PURPOSE

To assess the accuracy of moving-table MR angiography (MRA) in the evaluation of peripheral bypass grafts.

MATERIALS AND METHODS

There were 39 patients who had had peripheral bypass graft surgery and then subsequently underwent digital subtraction angiography (DSA) and contrast material-enhanced MRA, which was performed with moving-table software on a 1.0-T system before and during administration of 40 mL gadolinium. For evaluation, every bypass graft was divided into three parts and every leg into 14 segments. Disease severity was scored in four categories (0%-29%, 30%-69%, 70%-99%, 100%). Results were compared with those of the DSA. A total of 147 bypass graft segments and 938 vessel segments were classified.

RESULTS

In 132 of the assessable 147 bypass segments, disease gradings with both methods were congruent; however, 13 stenoses were misinterpreted by MRA for one grade and two additional lesions by two grades, leading to an accuracy in precise stenoses detection of 89.9%. The sensitivity and specificity values in the detection of bypass graft stenoses >69% (grade 3 + 4 lesions) reached 90.0% and 98.3%, respectively. In 821 of 938 vessel segments the accuracy of MRA in stenoses detection reached 87.5%. The sensitivity and specificity values in the detection of grade 3 + 4 lesions were 95.6% and 94.0% for the native vessels, respectively.

CONCLUSION

Moving-table MRA was as accurate in assessing bypass grafts as it was for the native arteries and showed a great accuracy in stenosis detection compared with DSA. Therefore, MRA is a promising modality for bypass graft surveillance and might be a noninvasive alternative to DSA in this regard.

Peripheral MR angiography

Peripheral arterial occlusive disease is a chronic and progressive disease with a reported incidence rate from 4.5% to 8.8% in men over 55 years of age. The diagnosis is usually made clinically, but for treatment planning and control, imaging of the peripheral arteries is required. Since its introduction in 1994, contrast-enhanced MR angiography has demonstrated a high diagnostic confidence and has replaced the invasive intra-arterial DSA, which is still the current gold standard for many different indications. For the peripheral arteries, clinical use of MR angiography was hampered for some years by the unsolved problem of the large imaging volume and the small diameter of the distal arteries. However, since the availability of ultra-fast high-gradient sequences and the possibility of moving-bed imaging, contrast-enhanced MR angiography, over the last few years, has shown its enormous potential and high accuracy in the diagnosis and follow-up of patients suffering from peripheral arterial occlusive disease. Exciting innovations in hardware and software allows very fast, very accurate, and very robust noninvasive imaging of the peripheral arteries, and both treatment planning as well as follow-up can be performed using contrast-enhanced MR angiography. The following review introduces the basic concepts of peripheral MR angiography--focusing on contrast enhanced imaging--and presents the different techniques as well as some potential limitations and how they could be solved. Finally, this article provides a look into the already-begun future of peripheral contrast-enhanced MR angiography with hybrid and combination techniques.

Comparison of Magnetic Resonance Angiography (MRA) and Duplex Ultrasound Arterial Mapping (DUAM) prior to infrainguinal arterial reconstruction

OBJECTIVE

the purpose of this study is to compare Magnetic Resonance Angiography (MRA) to Duplex Ultrasound Arterial Mapping (DUAM) and intraoperative findings to determine the clinical, accuracy of MRA for planning lower extremity revascularization procedures.

METHODS

forty-two patients who underwent lower extremity revascularization procedures had both MRA and DUAM evaluations. These data were analyzed retrospectively and two distinct endpoints were considered. First, we compared the MRA and DUAM findings for aorto-iliac, femoral-popliteal and infra-popliteal segments to intraoperative findings and evaluated the degree to which they agreed. Second, if there was a disagreement between imaging modalities, it was established whether a change in operative procedure would have resulted.

RESULTS

MRA and DUAM findings agreed in 26 of 31 cases (83%) of aorto-iliac segments, in 25 of 31 cases (81%) of femoral-popliteal segments, and in 16 of 21 cases (76%) of infra-popliteal segments. In total, DUAM agreed with intraoperative findings in 98% of cases while MRA agreed in 82% (p<.001). Disagreement between intraoperative findings and DUAM lead to an alternate surgical procedure in only one case (2%) while disagreement with MRA lead to a different procedure in 38% of cases (p<.001).

CONCLUSIONS

these data show that MRA is not yet adequate to replace conventional angiography and is less accurate that DUAM. Further improvements are necessary before MRA can be used as the sole modality for formulation of a pre-operative plan for lower extremity revascularization.

Lower extremity stepping-table magnetic resonance angiography with multilevel contrast timing and segmented contrast infusion

OBJECTIVES

Standard lower extremity contrast-enhanced magnetic resonance angiography (LE-CEMRA) with single injection bolus-chase methods on the basis of a single pelvis timing run can be accurate for depicting most vascular occlusive lesions but may fall short of catheter-based angiography when imaging tibial and pedal vessels. Magnetic resonance angiography techniques with a second contrast timing bolus and separate acquisitions for the calves and the pelvis greatly improve reliability and reduce venous contamination to levels that may render conventional angiography obsolete.

METHODS

From July to December 2001, 60 consecutive patients underwent LE-CEMRA of the calves with separate stepping-table acquisitions of the pelvis and thighs. Forty-five (75%) had complete or partial angiographic correlation during an endoluminal intervention or operative completion study. Lower extremity vessels were divided into anatomic segments (aortoiliac, femoropopliteal, tibial-pedal) for review. Three blinded observers assessed magnetic resonance source partitions, maximum-intensity projections, and volume-rendered images. Disease per segment was graded from insignificant (<20%) to occluded (100%) in 10% increments. Segments were also scored for venous contamination (scale, 0 to 3) and diagnostic quality (scale, 1 to 5). Digital subtraction angiograms were assessed similarly but separately.

RESULTS

The combination dual-timing/dual-injection technique had an overall sensitivity, specificity, and accuracy of 99%, 97%, and 98%. Venous contamination and artifact were virtually eliminated with combined technique LE-CEMRA. Diagnostic quality of calf and foot vessels was significantly superior to conventional bolus-chase magnetic resonance techniques (P <.01).

CONCLUSION

Hybrid dual-acquisition LE-CEMRA allows complete timing specification that consistently produces high-quality, artifact-free images of the calf and pedal vessels. These techniques may be accurate enough to replace conventional digital subtraction angiogram for evaluation of lower extremity vascular occlusive disease.

Ultrasound imaging of infrainguinal arterial disease has a high interobserver agreement

OBJECTIVES

to evaluate and compare the operator dependency of duplex ultrasound and digital subtraction arteriography (DSA) in patients suffering from chronic lower limb ischaemia.

DESIGN

prospective and blinded validation study.

MATERIAL

twenty-six consecutive patients (13 male and 13 females) with severe claudication (n=6, 23%), rest pain (n=7, 27%) or tissue loss (n=13, 50%).

METHODS

two physicians independently performed a duplex scan of the lower limb from groin to foot (15 segments). Segments were classified as insignificantly (<50% stenosis) or significantly (>50% stenosis or occlusion) diseased. DSA was performed within 24h of the duplex scanning and was independently reported by two radiologists in the same manner. Interobserver agreement was assessed for both diagnostic methods. After 10 months the arteriograms were reassessed and the intraobserver agreement calculated.

RESULTS

for the limb as a whole the interobserver agreement was good and similar for both duplex and DSA, with kappa-values of 0.79 (95%-CI: 0.72-0.86) and 0.80 (0.74-0.87). In the femoral, crural and pedal segments the interobserver agreement was similar for both methods. The intraobserver agreement between the two DSA readings was 0.84 (0.79-0.90).

CONCLUSION

ultrasound is comparable to arteriography when visualising arterial occlusive disease in patients with chronic lower limb ischaemia.

Selection of patients with infrainguinal arterial occlusive disease for percutaneous transluminal angioplasty with duplex scanning

AIM

To evaluate the role of duplex scanning in the selection of patients with infrainguinal arterial occlusive disease for percutaneous transluminal angioplasty (PTA).

MATERIAL AND METHODS

From January 1995 through May 2000, 702 patients (952 limbs), with chronic lower extremity ischemia due to infrainguinal atherosclerotic disease diagnosed by duplex scanning, were retrospectively studied. Diagnostic angiography (130 limbs) or infrainguinal PTA (108 limbs) was performed in 238 limbs. Two investigators retrospectively analyzed the duplex examinations and angiographies in a blinded manner and used similar criteria for the interpretation of lesions suitable or not suitable for PTA.

RESULTS

The superficial femoral, popliteal and crural artery lesions were correctly selected for PTA in 85%, 66% and 32%, respectively. The accuracy, sensitivity, specificity, negative predictive value and positive predictive value of duplex scanning to appropriately categorize femoropopliteal lesions as suitable or unsuitable for PTA were 89%, 83%, 92%, 94% and 78%, respectively. The accuracy of duplex scanning for predicting the performance of infrainguinal PTA was 83%.

CONCLUSION

Duplex scanning has an important impact on the selection of treatment modalities in limbs with infrainguinal arterial occlusive disease. Femoropopliteal lesions can be reliably selected to PTA according to duplex scan findings.

Duplex scanning as the sole preoperative imaging method for infrainguinal arterial surgery

OBJECTIVE

to evaluate preoperative duplex as the sole investigation prior to lower limb reconstruction. Design retrospective analysis.

MATERIALS AND METHODS

between January 1995 and December 1999, 157 of 329 surgical interventions for chronic infrainguinal arterial or aneurysmal disease were performed without preoperative angiography.

RESULTS

in patients undergoing femoral artery endarterectomy, the extent of the stenosis and the status of the distal deep femoral artery were correctly diagnosed with duplex scanning in all but one patient. Duplex scan findings in patients undergoing infrainguinal bypass procedures were in agreement with the findings obtained from on-table angiography in regard to the selection of optimal outflow anastomotic sites in 123 (98%). Duplex scanning correctly evaluated the status of runoff in 113 (90%). There were no significant differences in 30-day occlusion rate and patency at 12 months between reconstructions performed with and without preoperative angiography.

CONCLUSION

in patients with conclusive duplex scan findings there is no need to perform angiography prior to lower limb reconstruction.

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.

Surveillance of peripheral arterial bypass grafts with three-dimensional MR angiography: comparison with digital subtraction angiography

OBJECTIVE

The purpose of this study was to use contrast-enhanced three-dimensional MR angiography to assess the patency of peripheral arterial bypass grafts of the lower extremity.

SUBJECTS AND METHODS

The study included 39 patients with 45 lower limb grafts. Twenty-eight were saphenous vein grafts, 13 were expanded polytetrafluoroethylene, and two were Dacron grafts. Digital subtraction angiography correlation was available for 30 patients (31 grafts). MR angiography was performed on a 1.5-T system with a multichannel quadrature phased array peripheral vascular coil. The scanning delay was determined with a test bolus technique, using half-time to maximum signal intensity in the graft. Arterial imaging was accomplished with two three-dimensional MR angiography acquisitions with gadopentetate dimeglumine administered using an automated injector. The pelvic and femoral arteries were imaged, the MR table was repositioned, and the lower limb arteries were imaged. The three-dimensional MR angiography sequence used the following parameters: TR/TE, 5.2/1.5 msec; inversion time, 28 msec; flip angle, 30 degrees. The proximal anastomosis, graft, and distal anastomosis were characterized as normal, stenosed, occluded, or ectatic or aneurysmatic.

RESULTS

Sensitivity and specificity values for MR angiography regarding the assessment of grafts were 100% for 87 evaluable segments for which digital subtraction angiography correlation was available: stenosis (n = 10), occlusions (n = 9), ectasia or aneurysms (n = 8). Six segments could not be assessed because of the presence of intravascular stents or metallic clips.

CONCLUSION

Contrast-enhanced three-dimensional MR angiography is well suited for the characterization of arterial grafts, for planning subsequent vascular interventions, and for excluding further lesions.

Endovascular procedures under near-real-time magnetic resonance imaging guidance: an experimental feasibility study

PURPOSE

The purpose of this study was to assess the feasibility of insertion of endovascular stents and the precision of an open-field interventional magnetic resonance imaging (iMRI) system in an in vivo model.

METHODS

A feasibility study was undertaken at a university-affiliated hospital. Three male piglets with an average age of 6 months and a weight between 70 and 77 kg and two 3-month-old male piglets that weighed 40 to 44 kg were anesthetized. The five piglets underwent placement of nitinol stents inserted through the right femoral artery, under the guidance of a SIGNA-SP 0. 5T open-configuration iMRI unit. With a dedicated high-resolution near-real-time MRI sequence, the stent was guided and deployed onto a predefined target.

RESULTS

The main outcome measures were the duration of the procedure from the beginning of positioning to the end of deployment of the stent, the final position of the stent in relation to the target on the iMRI screen, and comparison with autopsy findings. Three stents were deployed within the aorta at the level of the renal arteries, and two were deployed within the right iliac artery just below the aortic trifurcation. The average duration of the endovascular deployment was 13 minutes. There was an agreement of 0.6 mm in the position of the stent as observed on iMR images and found at autopsy. When the piglets were sacrificed, the average distance between the stents and the predefined target was 7. 8 mm, mostly because of the migration of one stent. Axial views allowed for accurate determination of stent impaction on the vascular wall.

CONCLUSIONS

This study confirms the feasibility of stent deployment under near-real-time MRI guidance. It also emphasizes some inherent characteristics that hold promise with regard to other conventional techniques: stents and vascular structures are visualized in near-real-time in any desired plane, and the technique is performed without the potential adverse effects of ionizing radiations and iodinated contrast agents.

Lower extremity arteriography with use of iodinated contrast material or gadodiamide to supplement CO2 angiography in patients with renal insufficiency

PURPOSE

To determine if the use of nonionic contrast material, as compared to the use of gadodiamide to supplement carbon dioxide angiography in patients with peripheral vascular disease (PVD) and chronic renal insufficiency (CRI), results in significant worsening of renal function.

MATERIALS AND METHODS

Lower extremity angiographic procedures (diagnostic and diagnostic/intervention) were performed in 40 patients with CRI (baseline serum creatinine [Cr] > 1.5 mg/dL) using CO2 alone or CO2 supplemented with the use of either nonionic contrast material or gadodiamide (up to 0.4 mmol/kg). Serum creatinine levels were obtained before the procedure and at 48 hours after the procedure. The peak Cr level was also determined for patients with a significant (> 0.5 mg/dL) Cr elevation.

RESULTS

Forty-two lower extremity angiographic procedures (19 diagnostic and 23 diagnostic/interventions) were performed in 40 consecutive patients from August 1997 to October 1998, with a mean preprocedure Cr of 2.2 mg/dL and a mean postprocedure Cr of 2.4 mg/dL. Twenty-five of the 40 patients (63%) had diabetes mellitus. Fifteen procedures, including six interventions, were performed utilizing CO2 and nonionic contrast material in 15 patients. Six of these 15 patients (40%) demonstrated a Cr increase > 0.5 mg/dL at 48 hours. Seven procedures, including two interventions, were performed with CO2 alone in seven patients. No patients in this group demonstrated an increase in serum creatinine of greater than 0.5 mg/dL at 48 hours. Twenty procedures, including 15 interventions, were performed with CO2 and gadodiamide in 18 patients. In one of these 20 procedures (5%) there was an increase in Cr > 0.5 mg/dL at 48 hours The difference in worsening renal function for the nonionic contrast group (six of 15) compared with the CO2/gadodiamide group (one of 20) was statistically significant (P = .03). When comparing the use of CO2 and nonionic contrast material versus CO2 alone and with gadodiamide (six of 15 versus one of 27), the difference is also statistically significant (P < .01). The average volume of supplemental contrast material was similar in the nonionic contrast material and gadodiamide groups, as was the average volume of supplemental nonionic contrast material in the six patients with an increased Cr.

CONCLUSION

The use of small volumes of nonionic contrast material to supplement CO2 angiography in patients with PVD and CRI can be associated with a significant increased risk of worsening renal function when compared to angiography performed with CO2 alone or CO2 and gadodiamide.