MR angiography of the pedal arteries with gadobenate dimeglumine, a contrast agent with increased relaxivity, and comparison with selective intraarterial DSA

PURPOSE: To compare gadobenate dimeglumine (Gd-BOPTA)-enhanced MR angiography (i.e., contrast-enhanced MRA [CE-MRA]) of the pedal vasculature with selective digital subtraction angiography (DSA) in patients with peripheral arterial occlusive disease (PAOD). MATERIALS AND METHODS: A total of 22 patients with PAOD were prospectively examined at 1.5T. For contrast enhancement, 0.1 mmol/kg body weight of Gd-BOPTA were applied. MRA consisted of dynamic imaging with acquisition of six consecutive data sets. Acquisition time for each data set was 24 seconds, voxel size was 1.0 x 1.0 x 1.3 mm(3). A total of 20 out of 22 patient underwent selective DSA, two patients fine-needle DSA. DSA and MRA were performed within seven days. Image analysis was independently done by two observers with assessment of overall image quality, motion artifacts, detection of patent vessel segments of the distal calf and pedal vessels, and the number of patent metatarsal arteries. After four weeks, a consensus reading of DSA images was done. A second consensus reading of CE-MRA was performed after a further six weeks. RESULTS: Consensus readings of MRA and DSA revealed higher image quality and fewer motion artifacts for MRA (P = 0.021 and P = 0.008, respectively, sign test); interobserver agreement was good (kappa = 0.78) for image quality, and moderate (kappa = 0.46) for motion artifacts. There were no differences between CE-MRA and DSA in detecting patent vessel segments with a high degree of agreement (kappa = 0.89), and interobserver agreement for MRA was substantial (kappa = 0.89). Significantly more vessels were assessed as partially occluded on DSA than on CE-MRA (P = 0.004). There was a good agreement between DSA and CE-MRA for assessment of relevant vessel stenosis (kappa = 0.61); interobserver agreement for MRA was good (kappa = 0.65). CE-MRA detected significantly more patent metatarsal arteries than did DSA (P < 0.001). CONCLUSION: Gd-BOPTA-enhanced MRA is comparable to DSA for assessment of the pedal vasculature, and is able to delineate significantly more patent vessels without segmental occlusions and more metatarsal arteries than selective DSA.     

Doppler ultrasound and contrast-enhanced magnetic resonance angiography in assessing carotid artery stenosis

PURPOSE: This study prospectively compares Doppler ultrasound (Doppler US) and contrast-enhanced magnetic resonance angiography (CE-MRA) with digital subtraction angiography (DSA) and endarterectomy findings to determine the accuracy in assessing carotid artery stenosis. MATERIALS AND METHODS: Thirty-two patients underwent carotid endarterectomy, 21 studied with Doppler US, CE-MRA and DSA and 11 with Doppler US and CE-MRA. In 41 carotid arteries, the degree of stenosis was analysed with Doppler US and CE-MRA and compared with DSA by using the Spearman rank correlation coefficient. Nine out of 32 endarterectomies were done using the eversion technique, and it was possible to compare Doppler US, CE-MRA and DSA with the specimen measurement. Twenty-three out of 32 endarterectomies were done using the standard technique, and the presence of ulcers was documented. RESULTS: There was a significant Doppler US/DSA (Rs=0.86; p<0.001) and CE-MRA/DSA (Rs=0.81; p<0.001) correlation for the degree of stenosis. The diagnostic accuracy of the three methods was the same (89%). Ulcers were most frequently seen at CE-MRA, with a diagnostic accuracy of 85%. CONCLUSIONS: These data suggest that endarterectomy on the basis of Doppler US and CE-MRA can be considered appropriate. CEMRA was the best noninvasive imaging modality to detect plaque ulceration.     

Gadobenate dimeglumine-enhanced MR angiography: Diagnostic performance of four doses for detection and grading of carotid, renal, and aorto-iliac stenoses compared to digital subtraction angiography

PURPOSE: To determine the diagnostic performance of contrast-enhanced MR angiography (CE-MRA) with four doses of gadobenate dimeglumine for detection of significant steno-occlusive disease of the carotid, renal, and pelvic vasculature. MATERIALS AND METHODS: Eighty-four patients with suspected disease of the renal (n = 16), pelvic (n = 41), or carotid (n = 27) arteries underwent CE-MRA (3D-spoiled gradient-echo sequences) at 1.5T. CE-MRA was performed with gadobenate dimeglumine at 0.025, 0.05, 0.1, or 0.2 mmol/kg (23, 24, 19, and 18 patients, respectively) administered at 2 mL/sec. Accuracy, sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) for detection of significant disease (>50% stenosis or occlusion for renal/pelvic arteries; >70% stenosis or occlusion for carotid arteries) was determined by three fully blinded, independent radiologists using conventional digital subtraction angiography (DSA) as reference standard. All comparisons were tested statistically (ANOVA, chi-square, and Mantel-Haenszel tests as appropriate) and reader agreement (kappa) was assessed. RESULTS: Values for accuracy, sensitivity, specificity, PPV, and NPV on CE-MRA were consistently higher for 0.1 mmol/kg gadobenate dimeglumine (accuracy = 95.2-97.3%, sensitivity = 84.2% (all readers), specificity = 96.9-99.2%, PPV = 80.0-94.1%, NPV = 97.6-97.7%). The greater accuracy of the 0.1 mmol/kg dose was significant (P < 0.01, all readers) compared to all other dose groups. Agreement between the three readers was good for all dose groups (kappa >/=0.58), with the highest percent agreement (85.7%) noted for the 0.1 mmol/kg dose. CONCLUSION: Significantly better diagnostic performance on CE-MRA of the renal, pelvic, and carotid arteries is achieved with a gadobenate dimeglumine dose of 0.1 mmol/kg bodyweight.     

Magnetic resonance angiography with contrast media in the study of carotid arteries

PURPOSE: Purpose of our study was to determine the feasibility and accuracy of contrast enhanced Turbo-MRA (CE-MRA) in the evaluation of patients with carotid artery stenosis, using a dynamic technique with multiple acquisitions. MATERIAL AND METHODS: 37 patients with suspected carotid artery stenosis were studied with a 1.5 T magnet (Siemens Vision Plus) using, with a neck phased array coil, a dynamic tridimensional T1 weighted spoiled GRE (TR/TE/NEX: 3.8/1.4/1; Matrix = 110 x 160; FOV = 163 x 260 mm TA = 10 seconds for each sequence); 4 consecutive sequences were performed during the same breath hold, acquired after i.v. bolus injection with a power injector (Spectris, Medrad) of 15 ml of Gd-DTPA followed by 10 ml of saline solution (flow rate 2 ml/s). The beginning of the sequence coincided with the injection of Gd-DTPA. Images were reconstructed using a standard MIP algorithm, by selecting which of the sequences provided the highest enhancement. In all patients a DSA was also performed. Images were separately evaluated using conventional angiography as the gold standard and assessed for degree of stenosis by using NASCET criteria, and morphology of the plaque. RESULTS: CE-MRA correctly evaluated the degree of stenosis in 71 of the 74 patients, while overestimated the remaining 3 cases correctly evaluated by DSA. In 12 cases ulcerations were adequately demonstrated by one of the radiologist, while 11 on 12 were depicted by the other one. CE MRA allowed to detect tandem lesions of the internal carotid arteries (by both radiologists) in 13 of 74 carotids studied. Stenosis at the origin of the common carotid arteries were correctly detected in 9 cases. Sensitivity, specificity and accuracy were respectively of 98, 97 and 99%. DISCUSSION AND CONCLUSIONS: In order to perform an optimal CE-MRA a dynamic technique must be performed to avoid venous filling. The possibility to use ultrafast imaging allows to selectively image the carotid arteries without jugular filling. The well known tendency to overestimate the degree of stenosis has not been found in this group of patients. CE-MRA is a rapid, reliable method to evaluate patients with suspected carotid artery stenosis. These results allow to consider dynamic CE-MRA as a valid method for direct imaging of the carotid arteries.     

Contrast-enhanced 3D MR angiography of the carotid artery: comparison with conventional digital subtraction angiography

BACKGROUND AND PURPOSE: Since 1996, several preliminary studies have shown the usefulness of contrast material-enhanced MR angiography for imaging supraaortic vessels. The aim of this study was to compare the accuracy of contrast-enhanced 3D MR angiography with that of digital subtraction angiography (DSA) in the evaluation of carotid artery stenosis. METHODS: A blinded comparison of first-pass contrast-enhanced MR angiography with conventional DSA was performed in 120 patients (240 arteries). MR angiography was performed with a 1.5-T magnet with gradient overdrive equipment, by using a coronal radiofrequency-spoiled 3D fast low-angle-shot sequence after the intravenous injection of gadodiamide. The guidelines of the North American Symptomatic Carotid Endarterectomy Trial for measuring stenosis of the internal carotid artery were applied on maximum intensity projection (MIP) images and conventional catheter angiograms. RESULTS: Grading of stenoses on MR angiograms agreed with grading of stenoses on DSA images in 89% of arteries. In the severe stenosis group (70-99%), agreement was 93%. All internal carotid occlusions (n = 28) and seven of nine pseudo-occlusions were accurately detected with contrast-enhanced MR angiography. The correlation between MR angiography and DSA for determination of minimal, moderate, and severe stenoses and occlusion was statistically significant (r = 0.91, P<.001). CONCLUSIONS: This investigation with a large number of patients confirms that contrast-enhanced MR angiography could become a diagnostic alternative to DSA in the treatment of patients with carotid artery disease.     

三维对比剂增强MR血管成像对颈部动脉病变的诊断价值

目的　分析三维对比剂增强MR血管成像 (3DCE MRA)显示的颈部动脉常见病变 ;与DSA比较 ,明确 3DCE MRA诊断颈部动脉病变的价值。方法　对 741例超声多普勒怀疑颈部动脉疾病的患者进行 3DCE MRA成像 ,并根据其病变表现总结分类。 2 0 6例病人同时行DSA检查 ,将颈部动脉分为颈总、颈内、颈外、锁骨下及椎动脉 5个部位 ,由 2位放射学专家独立评估DSA及 3DCE MRA血管资料。结果　 3 6 7%病例 (2 72 / 741)显示无异常。 63 2 9% (469/ 741)显示颈部动脉有病变 ,共计 82 7段 ,其中动脉粥样斑块占 3 4 2 2 % (2 83段 ) ,动脉狭窄占 3 4 46% (2 85段 ) ,动脉闭塞占 3 3 8% (2 8段 ) ,动脉发育纤细占 14 87% (12 3段 ) ;动脉开口变异占 3 87% (3 2段 ) ,动脉扭曲占 3 63 % (3 0段 ) ,动脉瘤占 0 72 % (6段 ) ,动脉夹层占 1 2 1% (10段 ) ,肿瘤包绕或推压动脉占 1 45% (12段 ) ,术后复查占2 18% (18段 )。对 2 0 6例的 412段血管与DSA比较 ,3DCE MRA在颈总动脉、颈内动脉及椎动脉的阳性检出率差异有显著性意义 (P <0 0 1) ,主要是对动脉粥样斑块 (2 56段与 2 83段 )和动脉狭窄 (2 58段与 2 85段 )存在一定的高估。但对 412段血管整个样本 ,两种方法在同一部位诊断各种血管病变差异无显著性意义 (P >0 0     

Carotid artery stenosis: accuracy of contrast-enhanced MR angiography for diagnosis

PURPOSE: To assess accuracy of contrast material-enhanced magnetic resonance (MR) angiography as compared with three-dimensional (3D) time-of-flight (TOF) MR angiography and reference digital subtraction angiography (DSA) in diagnosis of carotid artery stenosis. MATERIALS AND METHODS: Enhanced and 3D TOF MR angiography and DSA were performed in 51 consecutive patients suspected of having carotid artery stenosis at duplex ultrasonography. Stenoses were measured by two independent observers blinded to clinical information and other test results. Pearson correlation coefficients were used, and kappa for interobserver variabilities was estimated. Sensitivity and specificity of enhanced and 3D TOF MR angiography were calculated and compared with those of DSA. RESULTS: Pearson correlation coefficients were 0.94 (P <.01) for enhanced angiography versus DSA, 0.92 (P <.01) for 3D TOF angiography versus DSA, and 0.93 (P <.01) for enhanced versus 3D TOF angiography for observer 1 and 0.94 (P <.01), 0.95 (P <.01), and 0.94 (P <.01), respectively, for observer 2. kappa statistics were 0.81 for enhanced angiography, 0.79 for 3D TOF angiography, and 0.78 for DSA. Stenosis measurements of observer 1 at enhanced MR angiography, with inclusion of carotid arteries on the symptomatic side only, compared with those of DSA yielded a sensitivity of 90% (95% CI: 68%, 99%) and a specificity of 77% (95% CI: 55%, 92%). 3D TOF angiography yielded a sensitivity of 86% (95% CI: 67%, 97%) and a specificity of 73% (95% CI: 50%, 89%) compared with those of DSA. For observer 2, sensitivity and specificity for enhanced angiography were 91% (95% CI: 70%, 99%) and 76% (95% CI: 52%, 91%), respectively, and 90% (95% CI: 68%, 99%) and 77% (95% CI: 51%, 92%), respectively, for 3D TOF angiography. CONCLUSION: Accuracy of enhanced MR angiography in diagnosis of severe stenosis is similar to that of 3D TOF MR angiography.     

Internal carotid artery stenosis: accuracy of subjective visual impression for evaluation with digital subtraction angiography and contrast-enhanced MR angiography

PURPOSE: To prospectively determine, for both digital subtraction angiography (DSA) and contrast material-enhanced magnetic resonance (MR) angiography, the accuracy of subjective visual impression (SVI) in the evaluation of internal carotid artery (ICA) stenosis, with objective caliper measurements serving as the reference standard. MATERIALS AND METHODS: Local ethics committee approval and written informed patient consent were obtained. A total of 142 symptomatic patients (41 women, 101 men; mean age, 70 years; age range, 44-89 years) suspected of having ICA stenosis on the basis of Doppler ultrasonographic findings underwent both DSA and contrast-enhanced MR angiography. With each modality, three independent neuroradiologists who were blinded to other test results first visually estimated and subsequently objectively measured stenoses. Diagnostic accuracy and percentage misclassification for correct categorization of 70%-99% stenosis were calculated for SVI, with objective measurements serving as the reference standard. Interobserver variability was determined with kappa statistics. RESULTS: After exclusion of arteries that were unsuitable for measurement, 180 vessels remained for analysis with DSA and 159 vessels remained for analysis with contrast-enhanced MR angiography. With respect to 70%-99% stenosis, SVI was associated with average misclassification of 8.9% for DSA (8.9%, 7.8%, and 10.0% for readers A, B, and C, respectively) and of 11.7% for contrast-enhanced MR angiography (11.3%, 8.8%, and 15.1% for readers A, B, and C, respectively). Negative predictive values were excellent (92.3%-100%). Interobserver variability was higher for SVI (DSA, kappa = 0.62-0.71; contrast-enhanced MR angiography, kappa = 0.57-0.69) than for objective measurements (DSA, kappa = 0.75-0.80; contrast-enhanced MR angiography, kappa = 0.66-0.72). CONCLUSION: SVI alone is not recommended for evaluation of ICA stenosis with both DSA and contrast-enhanced MR angiography. SVI may be acceptable as an initial screening tool to exclude the presence of 70%-99% stenosis, but caliper measurements are warranted to confirm the presence of such stenosis.     

Stenosis detection with MR angiography and digital subtraction angiography in dysfunctional hemodialysis access fistulas and grafts

PURPOSE: To prospectively assess three-dimensional contrast material-enhanced magnetic resonance (MR) angiography for stenosis depiction in malfunctioning hemodialysis arteriovenous fistulas (AVFs) and grafts (AVGs), as compared with digital subtraction angiography (DSA). MATERIALS AND METHODS: Ethical review board approval and written informed consent were obtained. MR angiography and DSA were performed in 51 dysfunctional hemodialysis fistulas and grafts in 48 consecutive patients. Vascular tree of accesses was divided into between three and eight segments depending on access type (AVF or AVG) and length of venous outflow. Images obtained with MR and DSA were interpreted by two MR radiologists and two interventional radiologists, respectively, who were blinded to information from each other and other studies. DSA was reference standard for stenosis detection. Sensitivity, specificity, and predictive values with 95% confidence intervals (CIs) of contrast-enhanced MR in detection of vascular segments containing hemodynamically significant (> or =50%) stenosis were calculated. Linear-weighted kappa statistic was calculated for contrast-enhanced MR and DSA to determine interobserver agreement regarding stenosis detection. RESULTS: A total of 282 vascular segments were evaluated. Contrast-enhanced MR depicted three false-positive stenoses and all but two of 70 significant stenoses depicted with DSA. Sensitivity, specificity, and positive and negative predictive values of MR in detection of vessel segments with significant stenoses were 97% (95% CI: 90%, 99%), 99% (95% CI: 96%, 100%), 96% (95% CI: 88%, 99%), and 99% (95% CI: 97%, 100%), respectively. MR demonstrated significant stenosis in four of five nondiagnostic DSA segments, whereas DSA showed no significant stenosis in four nondiagnostic MR segments. Linear-weighted kappa statistic for interobserver agreement regarding stenosis detection was 0.92 (95% CI: 0.89, 0.95) for MR and 0.95 (95% CI: 0.92, 0.97) for DSA. CONCLUSION: MR angiography depicts stenoses in dysfunctional hemodialysis accesses but has limited clinical value as result of current inability to perform MR-guided access interventions after stenosis detection. MR of dysfunctional access should be considered only if nondiagnostic vascular segment is present at DSA.     

Multidetector CT angiography of the aortoiliac system and lower extremities: a prospective comparison with digital subtraction angiography

OBJECTIVE: Our objective was to determine whether multidetector CT (MDCT) angiography is an accurate and reliable method of revealing atheroocclusive disease of the aortoiliac system and the lower extremities compared with digital subtraction angiography (DSA). SUBJECTS AND METHODS: Forty-one patients with ischemic legs underwent both MDCT angiography and DSA of the aortoiliac system and the legs. The arterial supply of the legs was divided into 35 segments. Three independent observers rated each segment according to the maximal degree of arterial stenosis. Consensus interpretation was used to calculate the sensitivity and specificity of MDCT angiography in showing arterial occlusions and stenoses of at least 75%. Intertechnique agreement was measured for each anatomic segment, and interobserver agreement was calculated for both techniques. Agreement was quantified using the kappa statistic. RESULTS: The sensitivity and specificity of MDCT angiography for depicting arterial occlusions and stenoses of at least 75% were 88.6% and 97.7%, and 92.2% and 96.8%, respectively. Substantial intertechnique agreement (kappa > 0.4) was present in 102 (97.1%) of 105 arterial segments. Substantial interobserver agreement was present in 104 (99.0%) of 105 comparisons for both MDCT angiography and DSA with an average kappa value of 0.84 for CT and 0.78 for DSA. MDCT angiography showed more patent segments than DSA (1192 vs 1091). All nine segments seen on DSA and not seen on MDCT angiography were in the calves. Of 110 segments seen on MDCT angiography and not seen on DSA, 100 (90.9%) were in the calves. CONCLUSION: MDCT angiography was accurate in showing arterial atheroocclusive disease with reliability similar to DSA. MDCT angiography showed more vascular segments than DSA, particularly within calf vessels.     

3.0T高分辨率CE-MRA对颈部血管狭窄的诊断价值

目的探讨三维对比增强磁共振血管成像(3D CE-MRA)在颈部动脉血管狭窄诊断中的临床应用价值。方法对23例临床拟诊颈部动脉血管狭窄行数字减影血管造影(DSA)的患者行颈部3D CE-MRA。将两种方法检查结果进行相关性比较。结果 23例患者共230个节段血管,3D CE-MRA显示了227个节段,共诊断出74处(32.6%)狭窄,其中28处轻度狭窄,22处中度狭窄,20处重度狭窄,4处闭塞;DSA共显示了230个节段的血管,共诊断出69处(30.4%)血管狭窄,其中24处轻度狭窄,23处中度狭窄,19处重度狭窄,3处闭塞。与DSA相比,3DCE-MRA对颈部动脉轻度、中度、重度狭窄及动脉闭塞的显示敏感性均为100%,特异性分别为85.71%、90.91%、90%和75%,两种检查方法对颈部动脉狭窄程度的判断有良好的一致性(κ=0.921,P=0.000)。结论 3.0T 3DCE-MRA能够可靠的评价颈部动脉狭窄性病变,基本可以替代DSA检查。     

Contrast-enhanced MR angiography of the carotid and vertebrobasilar circulations

BACKGROUND AND PURPOSE: Contrast-enhanced MR angiography (CE MRA) is a proven diagnostic tool in evaluation of the carotid arteries; however, few studies have addressed its accuracy in the vertebrobasilar system. The purpose of this study was to assess the sensitivity and specificity of CE MRA compared with digital subtraction angiography (DSA) for detection of vertebrobasilar disease. METHODS: Forty patients with suspected atherosclerotic disease of the carotid and vertebrobasilar circulations underwent CE MRA on a 1.5 T MR imaging scanner by use of a coronal 3D gradient-echo pulse sequence after intravenous injection of gadolinium diethylene triamine penta-acetic acid. All patients had correlative DSA within a 1-month period. CE MRA images were randomized and then independently assessed by 2 observers who were blinded to the DSA results. DSA examinations were analyzed in a similar manner. Each observer was asked to report the presence or absence of clinically significant stenosis (>50%), occlusion, fistula, aneurysm, and dissection. The MRA findings were then correlated with DSA. RESULTS: The sensitivity and specificity of MRA for detection of disease in the entire carotid and vertebrobasilar systems were 90% and 97%, respectively; for the carotid system alone, the sensitivity and specificity were 94% and 97%, respectively; and for the vertebrobasilar system they were 88% and 98% respectively. The overall interobserver reliability was 98% (kappa = 0.92). CONCLUSION: CE MRA is accurate at detecting disease not only in the carotid vessels, but also in the vertebrobasilar circulation, and has the potential to provide a comprehensive and noninvasive evaluation of the head and neck arteries in a single study.     

Magnetic resonance angiography of the carotid arteries using three different techniques: accuracy compared with intraarterial x-ray angiography and endarterectomy specimens

PURPOSE: To compare three different magnetic resonance angiography (MRA) techniques with x-ray angiography and endarterectomy specimens. MATERIALS AND METHODS: Twenty-one patients underwent x-ray angiography, three-dimensional time-of-flight (TOF) focusing on the carotid bifurcation, high-resolution (HR) contrast-enhanced (CE) MRA, and time-resolved CE MRA. Stenoses of internal carotid arteries were evaluated by three independent observers on identical projection of x-ray angiography and MRA. Maximum stenosis grades on MRA were assessed additionally and correlated with endarterectomy specimens in 12 cases. RESULTS: Sensitivity for the detection of severe stenoses was excellent (100%) for all MRA techniques, and specificity was superior for three-dimensional TOF (96.7%) compared with HR CE MRA (80.6%) and time-resolved CE MRA (83.9%). The correlation between x-ray angiography and MRA for all stenoses was slightly superior for three-dimensional TOF and HR CE MRA compared with the time-resolved technique (kappa = 0.87 and 0.86 vs. 0.84). The same trend was seen for the interobserver agreement and for the correlation with endarterectomy specimens. Eleven up to 17 stenoses (depending on the MRA technique) were graded higher using additional projections. CONCLUSION: Three-dimensional TOF MRA yielded even more accurate results than HR CE MRA in grading of stenoses near the carotid bifurcation. Therefore, a combination of both methods seems to be advantageous.     

Multi-detector row CT angiography in the assessment of carotid artery disease in symptomatic patients: comparison with rotational angiography and digital subtraction angiography

BACKGROUND AND PURPOSE: Compared with the single-detector technique, multi-detector row CT angiography permits larger anatomic coverage that includes both the epiaortic and entire carotid circulations. We evaluated the accuracy of multi-detector row CT angiography by using multiplanar reformation (MPR) for measuring carotid artery diameters compared with that of rotational angiography. We also evaluated the diagnostic performance of CT angiography compared with digital subtraction angiography (DSA). METHODS: In 35 patients, CT angiograms of 70 carotid arteries were compared with DSA images, and CT angiograms of 33 carotid arteries were compared with rotational angiograms. CT angiographic interpretation was performed first interactively at a workstation. Diameter measurements of normal and stenosed carotid arteries were performed on cross-sectional and oblique sagittal MPRs. Degree of stenosis was calculated per North American Symptomatic Carotid Endarterectomy Trial criteria independently by two observers for each technique. RESULTS: Degree of stenosis was slightly underestimated with CT angiography, with mean differences (+/- SD) per observer of 6.9 +/- 17.6% and 10.7 +/- 16.1% for cross-sectional and 2.8 +/- 19.2% and 9.1 +/- 16.8% for oblique sagittal MPRs compared with rotational angiography. CT angiography was somewhat inaccurate for measuring the absolute minimal diameter of high-grade stenoses. On symptomatic sides (n = 35), interactive CT angiographic interpretation combined with MPR measurements for lesions with a visual estimate of 50% or greater stenosis achieved a sensitivity of 95% (20/21) and specificity of 93% (13/14) in the detection of carotid stenosis (>/= 50%) verified with DSA. CONCLUSION: Regardless of slight underestimation of carotid stenosis with CT angiography compared with rotational angiography, diagnostic performance of CT angiography with interactive interpretation proved to be good. Also, the method is highly sensitive for detection of carotid artery stenosis, indicating the suitability of CT angiography as a screening method for symptomatic patients. For hemodynamically significant stenoses revealed by CT angiographic screening, conventional angiography still seems to be necessary.     

Multiphase magnetic resonance angiography of the abdominal and pelvic arteries: results of a bicenter multireader analysis.

RATIONALE AND OBJECTIVES: The objective is to assess the diagnostic accuracy and interobserver variability of multiphase 3D gadolinium-enhanced magnetic resonance angiography (3D-Gd-MRA) for assessment of abdominal and pelvic vascular disease. METHODS: In 41 patients from two different institutions multiphase 3D-Gd-MRA of the aorta and pelvis was performed using an identical scanning protocol. In a single breath-hold three to four consecutive phases were acquired. Stenoses in the renal arteries, and aorta and pelvic arteries were independently evaluated by three readers and compared with digital subtraction angiography. Interobserver variability was compared by means of a kappa statistic. RESULTS: Accuracy for stenosis grading consistently ranged between 80% and 90% for all three readers in all vessel segments studied. Good interobserver agreement was found with kappa values exceeding 0.75. Vessel segments with delayed fill-in could be reliably detected on the multiple successive MRA phases. Overall, MRA was rated slightly superior to Digital Subtraction Angiography in terms of interobserver variability, diagnostic confidence and image quality. CONCLUSIONS: Multiphase MRA is a highly robust technique with reproducible accuracy for different observers and different institutions. It can therefore be recommended for screening of atherosclerotic abdominal and pelvic disease.     

Peripheral arterial disease: comparison of color duplex US and contrast-enhanced MR angiography for diagnosis

PURPOSE: To prospectively compare the diagnostic accuracies of color duplex ultrasonography (US) and contrast material-enhanced magnetic resonance (MR) angiography and to assess interobserver agreement regarding contrast-enhanced MR angiographic findings in patients suspected of having peripheral arterial disease (PAD). MATERIALS AND METHODS: The institutional review board approved the study, and all patients provided signed informed consent. Two hundred ninety-five patients referred for diagnostic and preinterventional work-up of PAD with duplex US also underwent gadolinium-enhanced MR angiography. Data sets were reviewed for presence or absence of 50% or greater luminal reduction, which indicated hemodynamically significant stenosis, and to determine interobserver agreement. At duplex US, a peak systolic velocity ratio of 2.5 or greater indicated significant stenosis. Primary outcome measures were differences between duplex US and contrast-enhanced MR angiography in sensitivity and specificity for detection of significant stenosis, as assessed with the McNemar test, and interobserver agreement between the two contrast-enhanced MR angiogram readings, expressed as quadratic weighted kappa values. Intraarterial digital subtraction angiography (DSA) was the reference standard. RESULTS: Two hundred forty-nine patients had at least one hemodynamically significant stenotic lesion at contrast-enhanced MR angiography, duplex US, or both examinations. One hundred fifty-two patients underwent intraarterial DSA. The quadratic weighted kappa for agreement regarding the presence of 50% or greater stenosis at contrast-enhanced MR angiography was 0.89 (95% confidence interval [CI]: 0.87, 0.91). Sensitivity of duplex US was 76% (95% CI: 69%, 82%); specificity, 93% (95% CI: 91%, 95%); and accuracy, 89%. Sensitivity and specificity of contrast-enhanced MR angiography were 84% (95% CI: 78%, 89%) and 97% (95% CI: 95%, 98%), respectively; accuracy was 94%. Sensitivity (P = .002) and specificity (P = .03) of contrast-enhanced MR angiography were significantly higher. CONCLUSION: Results of this prospective comparison between contrast-enhanced MR angiography and duplex US provide evidence that contrast-enhanced MR angiography is more sensitive and specific for diagnosis and preinterventional work-up of PAD.     

Assessment of aortoiliac and renal arteries: MR angiography with parallel acquisition versus conventional MR angiography and digital subtraction angiography

PURPOSE: To prospectively compare the image quality, sensitivity, and specificity of three-dimensional gadolinium-enhanced magnetic resonance (MR) angiography accelerated by parallel acquisition (ie, fast MR angiography) with MR angiography not accelerated by parallel acquisition (ie, conventional MR angiography) for assessment of aortoiliac and renal arteries, with digital subtraction angiography (DSA) as the reference standard. MATERIALS AND METHODS: The study was approved by the institutional review board; informed consent was obtained from all patients. Forty consecutive patients (33 men, seven women; mean age, 63 years) suspected of having aortoiliac and renal arterial stenoses and thus examined with DSA underwent both fast (mean imaging time, 17 seconds) and conventional (mean imaging time, 29 seconds) MR angiography. The arterial tree was divided into segments for image analysis. Two readers independently evaluated all MR angiograms for image quality, presence of arterial stenosis, and renal arterial variants. Image quality, sensitivity, and specificity were analyzed on per-patient and per-segment bases for multiple comparisons (with Bonferroni correction) and for dependencies between segments (with patient as the primary sample unit). Interobserver agreement was evaluated by using kappa statistics. RESULTS: Overall, the image quality with fast MR angiography was significantly better (P=.001) than that with conventional MR angiography. At per-segment analysis, the image quality of fast MR angiograms of the distal renal artery tended to be better than that of conventional MR angiograms of these vessels. Differences in sensitivity for the detection of arterial stenosis between the two MR angiography techniques were not significant for either reader. Interobserver agreement in the detection of variant renal artery anatomy was excellent with both conventional and fast MR angiography (kappa=1.00). CONCLUSION: Fast MR angiography and conventional MR angiography do not differ significantly in terms of arterial stenosis grading or renal arterial variant detection.     

Interobserver agreement for the interpretation of contrast-enhanced 3D MR angiography and MDCT angiography in peripheral arterial disease

OBJECTIVE: The objective of our study was to compare interobserver agreement for interpretations of contrast-enhanced 3D MR angiography and MDCT angiography in patients with peripheral arterial disease. SUBJECTS AND METHODS: Of 226 eligible patients, 69 were excluded. The remaining 157 consecutive patients were prospectively randomized to either MR angiography (n = 78) or MDCT angiography (n = 79). Two observers independently evaluated for arterial stenosis or occlusion on MR angiography (2,157 segments) and MDCT angiography (2,419 segments) using a 5-point ordinal scale. Vessel wall calcifications were noted. Interobserver agreement for each technique was evaluated with a weighted kappa (kappa(w)) statistic. RESULTS: Although interobserver agreement for both was excellent, the interobserver agreement for MR angiography (kappa(w) = 0.90; 95% confidence interval [CI], 0.89-0.92) was higher than that for MDCT angiography (kappa(w) = 0.85; 95% CI, 0.83-0.86) for reporting the degree of arterial stenosis or occlusion in all segments. For the different anatomic locations, the interobserver agreement for MR angiography versus MDCT angiography was as follows: aortoiliac (kappa(w) =0.91 vs 0.84, respectively), femoropopliteal (kappa(w) = 0.91 vs 0.87), and crural (kappa(w) = 0.90 vs 0.83) segments. The interobserver agreement of MDCT angiography significantly decreased in the presence of calcifications but was still good for all anatomic locations. The lowest agreement was found for crural segments in the presence of calcifications (kappa(w) = 0.67). With MR angiography, there were 12 times more nondiagnostic segments than with MDCT angiography (81 vs 7, respectively). CONCLUSION: Interpretations of MR angiography and MDCT angiography for peripheral arterial disease have an excellent interobserver agreement. MR angiography has a higher interobserver agreement than MDCT angiography, and the presence of calcified segments significantly decreases interobserver agreement for MDCT angiography.     

Renal arteries: optimization of three-dimensional gadolinium-enhanced MR angiography with bolus-timing-independent fast multiphase acquisition in a single breath hold.

PURPOSE: To compare two different three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) angiographic techniques. MATERIALS AND METHODS: In 26 patients suspected of having renal artery stenosis, results with fast multiphase 3D MR angiography were compared to those with standard 3D MR angiography in 37 patients. With both techniques, 31-second breath-hold acquisitions were performed. Multiphase angiography comprised five discrete 6.4-second acquisitions without bolus timing, and standard angiography comprised a single acquisition based on test-bolus timing. Two readers evaluated images obtained with both techniques in terms of image quality, artifacts, and vessel conspicuity. Accuracy of findings on the multiphase 3D MR angiograms for assessment of renal artery stenosis was determined by comparing them to digital subtraction angiograms and surgical findings. RESULTS: In the early arterial phase, multiphase 3D MR angiograms showed no image degradation by venous overlay, whereas standard 3D MR angiograms depicted at least minor overlay in 53 of 83 renal arteries (P < .001). Less parenchymal enhancement in the early arterial phase resulted in a higher vessel conspicuity for the divisions and segmental arteries (P < .001). Both readers detected and correctly graded 18 of 20 stenoses on the multiphase angiograms with almost perfect interobserver agreement (kappa > 0.89). CONCLUSION: Renal multiphase 3D MR angiography is an accurate technique requiring no bolus timing. The performance of early arterial phase imaging leads to improved depiction, particularly of the distal renovascular tree, compared to that with standard single-phase 3D MR angiography.     

Initial experience with balanced turbo field echo in depicting carotid artery stenosis: comparison with multiple overlapping thin slab acquisition and 3D contrast-enhanced magnetic resonance angiography

PURPOSE: To compare balanced turbo field echo (bTFE) with multiple overlapping thin slice acquisition (MOTSA) and contrast-enhanced MR angiography (CE-MRA) in depicting carotid artery stenosis. MATERIALS AND METHODS: In this study 86 patients with cerebrovascular disease, who had been referred for a carotid examination, were imaged. All of the patients underwent MOTSA and one of four bTFE sequences followed by CE-MRA. Formatted maximum intensity projections (MIPs) and source images were read in a blinded fashion by a radiologist. Inter- and intrasequence statistical analyses were performed. RESULTS: We first compared image quality (IQ) and fat, background, and venous suppression using four distinct bTFE protocols in 118 carotid arteries, and found that bTFE4 performed the best. We then compared IQ, grades of stenosis, and background and venous suppression among bTFE4, MOTSA, and CE-MRA. bTFE produced significantly better IQ and venous suppression (P < 0.001), and higher SNR and CNR (P < 0.05) when compared to MOTSA. CONCLUSION: The bTFE sequence is robust and provides high-quality images in patients with mild to moderate carotid artery stenosis. Even though there is a tendency to overestimate stenosis with bTFE compared to CE-MRA, the shorter scan time of bTFE coupled with enhanced SNR and CNR measurements validates it as a clinically useful adjunct to MOTSA, if not a replacement.