Preoperative high-frequency duplex scanning of potential pedal target vessels

OBJECTIVE: The aim of this prospective study conducted at a tertiary referral center was to evaluate the efficacy of high-frequency duplex scanning in the preoperative evaluation of potential pedal target vessels.Material and methods The study population consisted of thirty-three consecutive diabetics suffering critical limb ischemia, with indications of infra-popliteal occlusive disease. Duplex ultrasound was performed by an angiologist unaware of any prior imaging procedures. The pedal vessels were divided into four segments. The inner diameter-, the grade of calcification (on a scale from 1-to-3), the maximal systolic velocity, and the resistance index ([V.max syst-V min syst]/V max syst), were assessed by using a 13-MHz probe, and the pedal target vessel best suited for surgery was identified.Results of duplex scanning were compared to (1) the results of selective digital subtraction angiography (DSA) and contrast-enhanced magnetic resonance angiography (CE-MRA) studies interpreted by two radiologists, (2) the site of distal anastomosis predicted by a vascular surgeon according to DSA and CE-MRA studies, (3) the definitive site of distal anastomosis, and (4) early postoperative results (patency at three months). RESULTS: Duplex scanning depicted significantly more pedal vascular segments than selective DSA- (P =.004, McNemar test). Agreement in predicting the site of distal anastomosis expressed as kappa value as follows: duplex versus DSA/CE-MRA, kappa 0.71;-DSA/CE-MRA versus definitive anastomosis, kappa 0.67; -and duplex versus definitive anastomosis kappa 0.82.Two patients were excluded from surgery as all three imaging modalities failed to demonstrate a pedal target vessel. Two patients had exploratory dissection of a pedal vessel (according to CE-MRA findings) that turned out to be occluded (as predicted by duplex scanning). In one patient the operation had to be terminated due to lack of autologous bypass material. In 31 patients who underwent pedal artery bypass, the resistance index could not be correlated to the run-off as assessed by intra-operative angiography. CONCLUSIONS: High-frequency duplex focusing on the vacular-morphology is a worthwhile diagnostic tool to evaluate-potential pedal target vessels and extremely helpful when contrast-related methods (selective DSA, CE-MRA) do not sufficiently depict the pedal vasculature.     

Colour-coded duplex imaging and dependent Doppler ultrasonography in the assessment of cruropedal vessels

BACKGROUND: It has been suggested that ultrasonography could replace diagnostic arteriography in the assessment of patients who present with leg ischaemia. This study investigated a group of consecutive patients who had femorodistal bypass and who were assessed before operation with colour-coded duplex and dependent Doppler insonation alone. METHODS: Thirty-seven consecutive patients with critical lower limb ischaemia underwent surgical exploration with a view to femorodistal bypass. Results of preoperative colour-coded duplex and dependent Doppler insonation were compared with intraoperative arteriograms and surgical findings. RESULTS: There was very good agreement between colour-coded duplex imaging and dependent Doppler insonation with intraoperative angiography and surgical findings in the prediction of the optimal run-off vessel (kappa = 1.0) and the site of the distal anastomosis (kappa = 0.85; 95 per cent confidence interval 0.71-1.0). There was also very good agreement between dependent Doppler insonation and intraoperative arteriography (kappa = 1.0) in predicting pedal arch patency and the predominant feeding vessel. CONCLUSION: Assessment of leg arteries before femorodistal bypass can be performed accurately with non-invasive colour-coded duplex imaging and dependent Doppler insonation alone, thus obviating the need for preoperative arteriography.     

Contrast-enhanced magnetic resonance angiography for preoperative imaging of deep inferior epigastric artery perforator flaps: advantages and disadvantages compared with computed tomography angiography: a United Kingdom perspective

The anatomy of the anterior abdominal wall is highly variable and leads to uncertainty when harvesting a deep inferior epigastric artery perforator flap. Presurgical imaging has been shown to reduce the operating time, as well as reduce the rates of flap and donor site complications. The importance of imaging of the venous system has also been recognized for reducing the risk of venous congestion. The modalities currently available for presurgical imaging include handheld Doppler ultrasound, duplex ultrasound, computed tomographic angiography (CTA), and contrast-enhanced magnetic resonance angiography (CE-MRA). Of these, the most promising are CTA and CE-MRA, and advantages and disadvantages exist for both modalities. In this article, we review the use of CE-MRA for preoperative flap imaging and report our experience with its use in deep inferior epigastric artery perforator flap harvest, as well as compare it with CTA. We also explore the future directions for presurgical flap imaging.     

Accuracy and utility of three-dimensional contrast-enhanced magnetic resonance angiography in planning carotid stenting

BACKGROUND: Contrast-enhanced magnetic resonance angiography (CE-MRA) is a proven diagnostic tool for the evaluation of carotid stenosis; however, its utility in planning carotid artery stenting (CAS) has not been addressed. This study assessed the accuracy of three-dimensional CE-MRA as a noninvasive screening tool, compared with digital subtraction angiography (DSA), for evaluating carotid and arch morphology before CAS. METHODS: In a series of 96 CAS procedures during a 2-year period, CE-MRAs and DSAs with complete visualization from the aortic arch to the intracranial circulation were obtained before CAS in 60 patients. Four additional patients, initially considered potential candidates for CAS, were also evaluated with CE-MRA and DSA. The two-by-two table method, receiver operating characteristic curve, and Bland-Altman analyses were used to characterize the ability of CE-MRA to discriminate carotid and arch anatomy, suitability for CAS, and degree of carotid stenosis. RESULTS: The sensitivity and specificity of CE-MRA were, respectively, 100% and 100% to determine CAS suitability, 87% and 100% to define aortic arch type, 93% and 100% to determine severe carotid tortuosity, and 75% and 98% to detect ulcerated plaques. CE-MRA had 87% sensitivity and 100% specificity for the detection of carotid stenosis >/=80%. The accuracy of CE MRA to determine optimal imaging angles and stent and embolic protection device sizes was >90%. The operative technique for CAS was altered because of the findings of preoperative CE-MRA in 22 procedures (38%). The most frequent change in the operative plan was the use of the telescoping technique in 11 cases (18%). CAS was aborted in four patients (5%) due to unfavorable anatomy identified on CE-MRA, including prohibitive internal carotid artery tortuosity (n = 1), long string sign of the internal carotid artery (n = 2), and concomitant intracranial disease (n = 1). Among patients considered suitable for CAS by CE-MRA, technical success was 100%, and the 30-day stroke/death rate was 1.6%. CONCLUSIONS: Contrast-enhanced magnetic resonance angiography of the arch and carotid arteries is accurate in determining suitability for CAS and may alter the operative technique. Certain anatomic contraindications for CAS may be detected without DSA. Although CE-MRA is less accurate to estimate the degree of stenosis, it can accurately predict imaging angles, and stent and embolic protection device size, which may facilitate safe and expeditious CAS.     

Gadolinium-enhanced magnetic resonance angiography, colour duplex and digital subtraction angiography of the lower limb arteries from the aorta to the tibio-peroneal trunk in patients with intermittent claudication.

OBJECTIVES: To evaluate the sensitivity, specificity, positive and negative predictive value of contrast-enhanced (gadolinium) magnetic resonance imaging (CE-MRA) and colour duplex ultrasound (CDU) of lower limb arteries. DESIGN: Prospective, single centre study. MATERIAL AND METHODS: A consecutive series of 58 patients with intermittent claudication (IC) were examined with CE-MRA and CDU from the infrarenal aorta to the tibio-peroneal trunk with digital subtraction angiography (DSA) as reference. The arterial tree was divided into 15 segments, pooled into three regions; suprainguinal, thigh and knee. Sensitivity, specificity, positive and negative predictive values for significant obstructions were calculated. Cohen Kappa statistics was used to establish agreement between the three methods. RESULTS: The sensitivity (specificity in parentheses) for significant obstructions in the suprainguinal region were 96% (94%) for CE-MRA and 91% (96%) for CDU, in the thigh region 92% (95%) for CE-MRA and 76% (99%) for CDU, and in the knee region 93% (96%) for CE-MRA and 33% (98%) for CDU. CDU failed to visualize 10% of suprainguinal, 2% of thigh and 13% of knee-region arterial segments. CONCLUSIONS: Both CE-MRA and CDU are good alternatives to DSA in the suprainguinal- and thigh-region. In the knee region only CE-MRA can be relied upon as an alternative to DSA. Imaging by CDU is not suited to situations were evaluation of runoff vessels is important.     

Die bildgebende Diagnostik pedaler Anschlussgefäße

In the case of critical forefoot ischemia, pedal artery bypasses can restore a palpable foot pulse and thus create the prerequisite for healing an ulcer or gangrene. The aim of this paper is to compare intra-arterial digital angiography, contrast-enhanced MR angiography and duplex sonography in order to detect pedal arteries suitable for bypass procedures. Selective angiography, injecting the contrast agent at the level of the femoral artery, is still the standard procedure. In the future, contrast-enhanced MR angiography will probably replace conventional angiography due to its noninvasive character. Duplex ultrasound using highly sensitive probes seems to be a valuable complementary tool and is the only means of gaining direct information about the blood flow in the pedal target vessel.     

Pedal artery imaging using DSA,CE-MRA and duplex

Diabetic macroangiopathy is associated with a typical disease pattern, mostly affecting the tibial but sparing the pedal arteries. Bypass grafts to these patent pedal vessels have evolved into a feasible technique. Restoring a palpable pulse in the ischemic foot they create the prerequisite to heal an ulcer or gangrene. Preoperative evaluation of pedal arteries demands a detailed depiction of the entire pedal vascular system. At present, the main options for preoperative pedal artery imaging are selective DSA contrast enhanced MRA and Duplex ultrasound. The aim of this review article is to give a survey of these three techniques and to determine their potential to depict pedal run off vessels. Selective DSA is still the standard diagnostic tool in preoperative pedal artery imaging. CE MRA offers high contrast related resolution but in-plane resolution is inferior to the concurrent imaging techniques. Duplex is the preferable method to evaluate a pedal artery's diameter and morphology. Both, CE MRA and Duplex are worthwhile additional imaging techniques in case DSA did not sufficiently depict the pedal vasculature.     

Assessment of apparent internal carotid occlusion on ultrasound: prospective comparison of contrast-enhanced ultrasound, magnetic resonance angiography and digital subtraction angiography.

OBJECTIVES: Modern conventional ultrasound is sensitive to slow flow, but may misclassify some tight stenoses as occlusion. Symptomatic patients with tight proximal internal carotid artery stenoses may benefit from carotid endarterectomy but those with occlusion or long-segment disease do not. DESIGN: A prospective study of the diagnostic accuracy of contrast-enhanced ultrasound (CE-US), 2D time-of-flight magnetic resonance angiography (2D-TOF MRA) and contrast-enhanced magnetic resonance angiography (CE-MRA) against a reference standard of digital subtraction angiography (DSA) in patients with apparent carotid occlusion on conventional ultrasound. MATERIALS AND METHODS: Thirty-one patients with apparent carotid occlusion on conventional ultrasound and with recent ispilateral hemispheric transient ischaemeic attacks (TIAs) were studied. The primary endpoint was confirmation of occlusion with a secondary endpoint of identification of a surgically correctible lesion. RESULTS: The sensitivity and specificity of CE-US, 2D-TOF MRA and CE-MRA for patency were 1 & 1, 0.33 & 1 and 0.6 & 1 respectively and for the detection of a surgically correctible lesion were 1 & 0.96, 0.67 & 1 and 1 and 0.96 respectively. CE-US was difficult to interpret, precluding confident diagnosis in 5 cases. CONCLUSIONS: 2D-TOF MRA had poor sensitivity for patency and cannot be recommended as a second-line investigation to assess vessels apparently occluded on conventional ultrasound. Confident diagnosis on CE-US and CE-MRA accurately identified occlusion. If occlusion is confirmed by either of these modalities, no further imaging is required. The relative advantages of CE-US or CE-MRA in this situation are uncertain.     

Comparison of intra-arterial digital subtraction angiography, magnetic resonance angiography and duplex ultrasonography for measuring carotid artery stenosis

BACKGROUND: Duplex ultrasonography and magnetic resonance angiography (MRA) are becoming competitive alternatives to angiography for determining the degree of internal carotid artery (ICA) stenosis. Varying reports have been published regarding the suitability of each technique for grading ICA disease. This retrospective study compared the merits of these three modalities for measuring ICA stenosis. METHODS: One hundred and eleven patients being considered for carotid endarterectomy underwent intra-arterial digital subtraction angiography (DSA) via arch injection. Duplex imaging was performed in all patients and MRA in 50. The degree of carotid stenosis estimated by the three modalities was compared. RESULTS: There was good correlation between subjectively graded MRA and DSA images (r = 0.87, P < 0.001, n = 82 carotids) but poor correlation for objective estimates. MRA tended to underestimate the degree of stenosis (bias - 4.5 per cent) compared with DSA, but showed good correlation with duplex ultrasonography estimates (r = 0. 86, P < 0.001, n = 87 carotids). Both non-invasive modalities produced high values of sensitivity and specificity in estimating stenoses of greater than 70 per cent. MRA was less sensitive for distinguishing between severe stenosis and complete occlusion. CONCLUSION: This study did not resolve the debate regarding the method of choice as both MRA and duplex ultrasonography were accurate for imaging carotid stenoses.     

Overestimation of carotid artery stenosis with magnetic resonance angiography compared with digital subtraction angiography

BACKGROUND AND PURPOSE: Three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) is generally considered to overestimate the degree of stenosis in the internal carotid artery (ICA) in comparison with the reference standard intraarterial digital subtraction angiography (DSA). We evaluated whether the degree of stenosis was more accurately assessed with 3D TOF MRA if corresponding projections on MRA and DSA were compared instead of comparison of maximal stenosis at MRA with maximal stenosis at DSA. METHODS: From February 1997 to December 1999, we included 186 symptomatic and 17 asymptomatic consecutive patients suspected of having carotid artery stenosis on the basis of clinical presentation and screening with duplex ultrasound scan examination. All patients subsequently underwent DSA and MRA imaging. From each ICA, 12 maximum intensity projections with 3D TOF MRA and two or three projections with DSA were obtained. First, we compared the maximal stenosis at MRA with the maximal stenosis at DSA. Subsequently, we used the stenosis at MRA measured on the projection corresponding with the DSA projection that showed the maximal stenosis. For both strategies, the mean differences in stenosis and sensitivity and specificity for assessment of severe stenosis (70% to 99%) were calculated and compared. RESULTS: The MRA and DSA images of 354 ICAs could be compared. The sensitivity and specificity of MRA with the projection that showed the maximal stenosis were 92.6% (95% CI, 85.3% to 97.0%) and 82.7% (95% CI, 78.1% to 87.3%), respectively. The sensitivity and specificity with the MRA projection, corresponding with the DSA projection showing the maximal stenosis, were 88.3% (95% CI, 81.8% to 94.8%) and 89.6% (95% CI, 85.9% to 93.3%), respectively. The mean difference between maximal stenosis at MRA and DSA was 7.5% (95% CI, 5.2% to 9.9%). The mean difference between stenosis at MRA and DSA in corresponding projections was 0.4% (95% CI, -2.0% to 2.7%). CONCLUSION: If corresponding MRA and intraarterial DSA projections are compared, 3D TOF MRA does not overestimate carotid stenosis.     

Contrast-enhanced magnetic resonance angiography of mammary artery grafts after minimally invasive coronary bypass surgery

BACKGROUND: The aim of the study was to investigate the application of the contrast-enhanced magnetic resonance angiography (CE-MRA) for the visualization of left internal mammary artery (LIMA) bypass. METHODS: A total of 30 patients with LIMA bypass (22 men, 8 women, 35 to 77 years) received a CE-MRA 4 to 20 days after surgery. The non-ECG-triggered CE-MRA was performed during expiration using a body array coil at a 1.5 Tesla scanner (Magnetom-Vision). A three-dimensional gradient-echo sequence with slice interpolation technique was applied. For the three-dimensional visualization, single coronal slices were postprocessed with maximal intensity projection. Of 30 patients 22 agreed to a comparative coronary angiography. RESULTS: Five bypasses were identified up to the end-to-side anastomosis. A total of 80% of the bypass course was detectable in 13 patients and 60% in 11 patients. In two LIMA bypasses only 30% of the proximal part could be viewed; one was found by conventional coronary angiography to be occluded. The other conventional coronary angiography showed the LIMA bypass to be patent. CONCLUSIONS: The complete course of the LIMA bypass to the left anterior descending coronary artery can be visualized by the MRA technique. The most reliable imaging of the distal anastomosis can be realized by reducing the negative influence of the beating heart.     

Pedal bypass grafting on arteriographically invisible foot arteries detected by duplex ultrasound for limb salvage

AIM: In this study the long-term outcomes in patients undergoing pedal bypass grafting were evaluated and the risk of graft occlusion was related to whether, preoperatively, the pedal arteries were visualized by angiography or not and were only detected by duplex ultrasonography. METHODS: In 2000-2005, 81 pedal bypass grafts were performed in patients with chronic critical lower-limb ischemia, of which 54 (66.7%) had diabetes. Tissue loss (SVS/ISCVS-category 5) was recorded in 68 (84%) limbs and rest pain (SVS/ISCVS-category 4) in 13 (16%) limbs. In 24 limbs (29.6%) bypass grafts were implanted on the pedal arteries that had not been visualized by preoperative angiography, but had been detected only by duplex ultrasound. RESULTS: During the follow-up (median, 17 months; range, 3-69 months), 18 grafts (22.2%) failed. Seven limbs had to be treated by early thrombectomy, which resulted in long-term graft patency and limb salvage. The early postoperative mortality rate was 2.5%. Cumulative primary and secondary graft patency rates, and limb-salvage rates were 70.2%, 80.2% and 82.4%, respectively. No significant difference in graft occlusion was found between the patients with visible and those with not visible pedal arteries on preoperative arteriograms (Fisher's exact test). CONCLUSIONS: Duplex ultrasonography is a reliable modality for detection of target pedal arteries not visualized by preoperative arteriography and it helps reduce the number of patients with non-operable arterial occlusion disease by about 25%.     

三维增强核磁共振血管造影在内脏动脉瘤诊治中的应用

目的 探讨三维增强核磁共振血管造影在内脏动脉瘤诊治中的临床价值.方法 对43例内脏动脉瘤患者行三维增强MR血管造影检查,19例同期行数字减影血管造影(digital subtraction angiography,DSA).三维增强MR血管造影用屏气超快速三维梯度回波序列,图像减影后进行三维重建.结果 43例共50个内脏动脉瘤,涉及脾动脉32个(其中5例脾动脉异位起源于肠系膜上动脉),占64%;肠系膜上动脉7个(14%),腹腔动脉干5个(1例为腹腔系膜干),肾动脉4个,肝动脉2个.三维增强MR血管造影能清楚显示动脉瘤部位、大小、形态,并在立体直观显示动脉瘤及其与周围血管脏器关系方面优于DSA.43例中,行栓塞治疗15例,手术9例,保守观察19例.结论 三维增强MR血管造影能尤创、准确诊断内脏动脉瘤,所提供的三维解剖细节有助于临床治疗方案的制定,可作为内脏动脉瘤的首选检查方法.     

Diagnostic imaging of carotid stenosis: ultrasound, magnetic resonance imaging, and computed tomography angiography

Carotid artery stenosis is increasingly a cause of stroke in Japan. Diagnostic imaging techniques are available, including ultrasound, 3D computed tomography angiography (CTA), magnetic resonance imaging (MRI), and cerebral angiography (DSA). The stenosis ratio measuring vessel diameter is a major criteria for surgical indications. CTA and DSA are definitive diagnostic procedures. Plaque imaging reveals a lipid-rich core, intraplaque hemorrhage, and thin fibrous cap. Atheromatic plaque with these components of vulnerable plaque is also a risk factor for stroke in addition to the stenosis ratio. As screening methods, ultrasound and magnetic resonance angiography are useful. Ultrasound and MRI provide valuable information on plaque imaging. Angiography remains essential for carotid stenting. For screening study prior to surgical or endovascular treatment and follow-up, the appropriate imaging modality should be selected for each patient with carotid stenosis to prevent stroke.     

Preoperative angiographic score and intraoperative flow as predictors of the mid-term patency of infrapopliteal bypass grafts.

OBJECTIVES: preoperative angiographic characteristics of the outflow tract have emerged as a predictive factor for the outcome of infrapopliteal reconstructions. Direct flow measurement can be routinely performed intraoperatively, but little is known regarding its impact on graft outcome. The present study was undertaken to compare the value of these parameters in predicting the mid-term patency of infrapopliteal bypass grafts. DESIGN: retrospective clinical study. PATIENTS: 172 infrapopliteal reconstructions using autogenous vein were performed, of which 92 had a crural and 80 a pedal recipient artery. METHODS: the preoperative angiogram was scored according to the SVS/ISCVS Ad Hoc Committee. At the end of the operation flow was measured with a transit-time flowmeter. Follow-up consisted of pressure measurements and duplex scanning. RESULTS: the runoff score had no impact on femorocrural graft patency. For pedal grafts there was a tendency for inferior outcome with high runoff score, as the 1-year assisted primary patency for grafts with a completely occluded pedal arch was 11% compared with 52% for grafts with lower scores (p=0.056). Both intraoperative volume graft flow and maximum flow capacity had a highly significant influence on the outcome on crural reconstructions on univariate analysis. For pedal reconstructions only a a severely reduced maximum flow capacity after injection of papaverin was associated with an adverse outcome. Multivariate analysis revealed that maximum flow capacity was an independent significant factor affecting patency of femoroinfrapopliteal grafts (relative risk=0.53 per 30 ml/min increase, p<0.001). The runoff score was also a weak independent predictor of 1-year assisted primary patency in these grafts (relative risk=1.9 for a score >4 in crural and a score >5.5 in pedal grafts, p=0.036). CONCLUSIONS: a completely occluded pedal arch in preoperative angiography was associated with poor infrapopliteal bypass outcome. Graft flow and maximal flow capacity are good predictors of the 1-year graft patency of femorocrural bypasses.     

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.     

Comparison of duplex ultrasound with digital subtraction angiography in the assessment of infra-inguinal autologous vein bypass grafts

BACKGROUND: Postoperative surveillance of infra-inguinal vein grafts has arisen because of the high incidence of vein graft stenoses, which frequently progress to vein graft occlusion. The use of duplex ultrasound as the primary imaging method for graft surveillance is well established. This study aims to compare the accuracy of duplex ultrasound with the reference standard of digital subtraction angiography in the assessment of infra-inguinal vein grafts. METHODS: Sixty patients underwent routine postoperative duplex ultrasound as part of the local graft surveillance programme. Angiography was subsequently carried out on 18 grafts. Each lower limb arterial tree was divided into three segments (native arteries proximal to the graft, the graft itself and native arteries distal to the graft) resulting in a total of 42 comparisons. Degree of diameter stenosis on ultrasound was compared with angiography findings to determine concordance. Agreement was also expressed as a kappa value. RESULTS: Overall accuracy of duplex ultrasound was 88% (37/42). A kappa value of 0.80 indicates good agreement. In three of the five discordant cases, ultrasound correctly identified a stenosis, but overestimated the degree of stenosis compared with angiography. In each of the remaining two discordant cases, ultrasound identified a focal stenosis that was not apparent on angiography. In both cases, the area of duplex described abnormality responded to balloon angioplasty. CONCLUSION: Duplex ultrasound as part of the local vein graft surveillance programme is a reliable and accurate method in the detection of failing grafts and in some instances may be more sensitive.     

Morphologic and functional magnetic resonance imaging of renal artery stenosis: a multireader tricenter study.

The effect of combined morphologic and functional magnetic resonance (MR) imaging on the interobserver and intermodality variability for the grading of renal artery stenosis is assessed. In a randomized, blinded tricenter analysis, seven readers evaluated 43 renal arteries on x-ray digital subtraction angiography (DSA), 3D-Gadolinium MR angiography (3D-Gd-MRA), cine phase-contrast flow measurement (PC-flow), and a combined analysis of the last two. Interobserver variability was assessed for the grading of renal artery stenosis as well as regional vessel visibility. Intermodality variability for stenosis grading was analyzed in cases in which the readers agreed on the degree of stenosis in DSA. DSA had a substantial interobserver variability for the grading of stenosis (mean kappa kappa 0.64). 3D-Gd-MRA revealed a slightly improved interobserver variability but incorrectly graded 6 of 34 stenoses on a two-point scale (<50%, > or =50%). The combined approach of 3D-Gd-MRA and PC-flow revealed the best (P = 0.0003) interobserver variability (median kappa = 0.75) and almost perfect intermodality agreement with DSA (97% of cases). These findings were confirmed in a prospective analysis of 97 renal arteries. The vessel visibility of the renal artery ostium was significantly better in 3D-Gd-MRA than in DSA, whereas the visibility of the hilar and intrarenal vessels was significantly worse (P = 0.0001). A combined morphologic and functional MR examination significantly reduces interobserver variability and offers reliable and reproducible grading of renal artery stenosis based on stenosis morphology and hemodynamic changes. It can be considered a safe and noninvasive alternative for diagnostic DSA in cases that do not require assessment of intrarenal vessels.     

Patients' preferences for MR angiography and duplex US in the work-up of peripheral arterial disease.

PURPOSE: To measure patients' preferences for magnetic resonance (MR) angiography and duplex ultrasound (US) in the imaging work-up of peripheral arterial disease (PAD). METHODS: Ninety-eight patients, who underwent both MR angiography and duplex US, received a questionnaire by mail and their preferences for imaging work-up were assessed in a telephone interview. The questionnaire consisted of one question on which imaging test they preferred, a rating scale score ranging from 0 (not bothersome at all) to 10 (extremely bothersome), and specific questions on whether patients experienced discomfort due to the imaging work-up. Responses were presented as means and frequencies, and differences were tested by non-parametric tests. RESULTS: Half of the patient population (50%) had no preference for MR angiography or duplex US, 41% had a preference for MR angiography, and 9% had a preference for duplex US. The average rating scale scores for MR angiography (1.6) and duplex US (1.7) were not significantly different (p=0.53). Four out of 98 (4%) patients responded that they experienced pain during the MR angiography versus 18 (18%) for duplex US (p=0.001). Eight out of 98 (8%) patients responded that they were anxious during the MR angiography versus 1 (1%) for duplex US (p=0.02). CONCLUSION: The results suggest that the majority of patients have no preference between MR angiography and duplex US in the diagnostic work-up of PAD. Among patients who do have a preference, MR angiography was preferred over duplex US.     

Gadolinium-enhanced three-dimensional magnetic resonance angiography versus conventional digital subtraction angiography: which modality is superior in evaluating living kidney donors?

This study evaluates the correlation of magnetic resonance angiography (MRA) and digital subtraction angiography (DSA) with the operative vessel findings in living kidney donors. The intraoperative vessel findings of 52 living renal donors were compared with the preoperative diagnoses of each imaging technique. Sixty-seven arteries were found during explantation. Forty kidneys showed a single arterial blood supply, and 12 kidneys showed a multiple arterial blood supply. No advantage of either imaging method was found for arterial imaging. There were 55 veins identified during organ harvesting. MRA could not determine the venous system in one donor (1.9%) and failed to detect one small pole vein in another. DSA did not yield a venous diagnosis in seven patients (13.5%) and yielded misdiagnoses in four patients. The correct diagnosis of renal donor veins differed significantly in favor of MRA (kappa 0.79 vs. 0.45; P=0.008). MRA is superior to DSA in assessing the renal vasculature in living kidney donors.