CT angiographic analysis of carotid artery stenosis: comparison of manual assessment, semiautomatic vessel analysis, and digital subtraction angiography

BACKGROUND AND PURPOSE: To compare multisection CT angiography (CTA) analyzed with source/maximum intensity projection (MIP) images as well as semiautomated vessel analysis software with intra-arterial digital subtraction angiography (DSA) in detection and grading of carotid artery bifurcation stenosis. METHODS: Consecutive patients with sonography evidence of a marked internal carotid artery stenosis underwent both carotid CTA and DSA (37 patients, 73 vessels). In CTA, the grade of stenosis was determined using axial source and MIP images as well as vessel analysis. The scans were blind-analyzed by 2 neuroradiologists using the NASCET criteria. RESULTS: Correlation of CTA source/MIP images versus DSA estimates of stenosis (R = 0.95) was higher than for the vessel analysis method versus DSA (R = 0.89). Compared with DSA, CTA source/MIP images underestimated high (78.2% versus 86.4%, P < .05) and moderate grades of stenosis (57.3% versus 63.1%, P < .05) to a lesser extent than the vessel analysis method (68.5% versus 83.5% and 51.8% versus 63.1%, P < .05). For a high-grade stenosis, sensitivity and specificity of source/MIP image CTA were 75% and 96%, respectively, whereas for the vessel analysis method, they were 47% and 96%, respectively. For moderate stenosis, the source/MIP image CTA sensitivity and specificity were 88% and 82%, respectively, and for vessel analysis method, 62% and 82%, respectively. CTA detected all 4 occlusions. CONCLUSION: In evaluation of carotid stenosis, CTA provides an adequate, less invasive alternative with a high correlation to conventional DSA, though it tends to underestimate clinically relevant grades of stenosis. Its accuracy is not improved by semiautomated analysis. The data support the use of CTA in confirming carotid occlusion.     

CT angiography,MR angiography and rotational digital subtraction angiography for volumetric assessment of intracranial aneurysms. An experimental study

The purpose of our experimental study was to assess the accuracy and precision of CT angiography (CTA), MR angiography (MRA) and rotational digital subtraction angiography (DSA) for measuring the volume of an in vitro aneurysm model. A rigid model of the anterior cerebral circulation harbouring an anterior communicating aneurysm was connected to a pulsatile circuit. It was studied using unenhanced 3D time-of-flight MRA, contrast-enhanced CTA and rotational DSA angiography. The source images were then postprocessed on dedicated workstations to calculate the volume of the aneurysm. CTA was more accurate than MRA (P=0.0019). Rotational DSA was more accurate than CTA, although the difference did not reach statistical significance (P=0.1605), and significantly more accurate than MRA (P<0.00001). CTA was more precise than MRA (P=0.12), although this did not reach statistical significance. Rotational DSA can be part of the diagnosis, treatment planning and support endovascular treatment of intracranial aneurysms. The emerging endovascular treatment techniques which consist of using liquid polymers as implants to exclude aneurysms from arterial circulation would certainly benefit from this precise measurement of the volume of aneurysms.     

MR和CT血管造影在诊断颈动脉狭窄及内膜切除术后随访中的价值

目的 探讨磁共振血管造影（MRA）、CT血管造影（CTA）在诊断颈动脉狭窄及内膜切除术后随访中的价值。方法 11例22支颈动脉行MRA、CTA、CT仿真内窥镜（CTVE）、多普勒超声（DUS）检查。12支结果与DSA对照。3支颈动脉重度狭窄者行内膜切除术,MRA采用二维、三维时间飞越法。CTA经最大强度投影（MIP）及遮盖表现显示法（SSD）三维重建。应用导航功能行CTVE成像。结果 颈动脉轻度狭窄8支,中度狭窄3支,重度狭窄5支,闭塞1支,5支正常。12支颈动脉与DSA对照：CTA评估血管狭窄与DSA相符者11支,MRA与DSA相符者9支,DUS与DSA相符者7支。CTA、CTVE显示斑块、壁血栓6支,3支手术证实。术后MRA示狭窄解除,CTA示斑块消失。结论 MRA、DUS可用于颈动脉狭窄的筛选及术后随访。CTA评估血管狭窄程度与DSA、手术比较有较好的一致性,并能直接显示钙化斑块。     

Intracranial stenoocclusive disease: double-detector helical CT angiography versus digital subtraction angiography.

BACKGROUND AND PURPOSE: To our knowledge, no large-scale studies comparing the accuracy of CT angiography (CTA) to intraarterial digital subtraction angiography (DSA) of intracranial stenosis have been reported. We attempted to determine the diagnostic value of intracranial CT angiography (CTA) of normal vasculature and variants as well as of stenoocclusive disease. METHODS: One-hundred and twelve patients underwent CTA and intraarterial angiography, and 2205 vascular segments were examined to ascertain presence, visibility, and degree of arterial stenoses (n = 105) as well as anatomic variants. Source, maximum intensity projection (MIP), and MIP-generated multiplanar reformatted (MPR) images were evaluated. RESULTS: All 55 anatomic variants were identified correctly. Visibility of small-vessel segments was increased from 75% to 83% by using source images. MPR was helpful in differentiating distal vertebral hypoplasia from stenosis and in overcoming artifacts. All 43 occlusive segments were graded correctly (sensitivity = 100%, predictive value = 93.4%) as follows: severely stenotic ([n = 23], sensitivity = 78%, predictive value = 81.8%); moderately stenotic ([n = 36], sensitivity = 61%, predictive value = 84.6%); and mildly stenotic ([n = 3], sensitivity = 66%, predictive value = 28%). Normal segments (n = 2100) had a sensitivity of 99.5%, and CTA evinced a specificity of 99% for detecting stenoocclusive disease. Approximately one-third of wrong assessments were related to the petrous segment of the carotid artery. CONCLUSION: CTA with double-detector technology and advanced postprocessing algorithms, including MPR, is about as reliable as MRA in depicting the vasculature of the anterior and posterior circulation and in grading intracranial stenoocclusive lesions, with the exception of the petrous segment of the carotid artery. CTA might be superior to MRA in the evaluation of poststenotic low-flow segments.     

3 T contrast-enhanced magnetic resonance angiography for evaluation of the intracranial arteries: comparison with time-of-flight magnetic resonance angiography and multislice computed tomography angiography

PURPOSE: We sought to prospectively evaluate the image quality and visualization of the intracranial arteries using high spatial resolution contrast-enhanced magnetic resonance angiography (CE-MRA) at 3 T and to perform intraindividual comparison with time-of-flight (TOF) MRA and multislice CT angiography (CTA). MATERIALS AND METHODS: Twelve patients (5 men, 7 women, 37-71 years of age) with suspected cerebrovascular disease prospectively underwent MRA and CTA. MRA was performed on a 3 T MR system, including both 3-dimensional (3D) TOF (Voxel dimension: 0.6 x 0.5 x 0.9 mm in 5 minutes and 40 seconds) and 3D CE-MRA (voxel dimension: 0.7 x 0.7 x 0.8 mm in 20 seconds, using parallel acquisition with an acceleration factor of 4). CTA images were acquired on a 16-slice CT scanner (voxel dimension: 0.35 x 0.35 x 0.8 mm in 17 seconds). The image quality and visualization of up to 26 intracranial arterial segments in each study was evaluated by 2 experienced radiologists. The arterial diameter for selective intracranial arteries was measured independently on each of the 3 studies, and statistical analysis and comparative correlation was performed. RESULTS: A total of 312 arterial segments were examined by CE-MRA, TOF-MRA, and CTA. The majority of intracranial arteries (87%) were visualized with diagnostic image quality on CE-MRA with a significant correlation to TOF (R values = 0.84; 95% confidence interval 0.79-0.86, P < 0.0001), and to CTA (R values = 0.74; 95% confidence interavl 0.68-0.78, P < 0.001). The image quality for small intracranial arteries, including the anterior-inferior cerebellar artery, the posterior communicating artery, and the M3 branch of the middle cerebral artery, was significantly lower on CE-MRA compared with TOF and CTA (P < 0.03). There was a significant correlation for the dimensional measurements of arterial diameters at CE-MRA with TOF (r = 0.88, 95% confidence interval 0.81-0.93), and CTA (r = 0.83, 95% confidence interval 0.73-0.90). CONCLUSION: The described 3 T CE-MRA protocol, spanning from the cervical to the intracranial vessels, visualized and characterized the majority of intracranial arteries with image quality comparable with that obtained using TOF-MRA and CTA. Further clinical studies are required to establish the accuracy of the technique in a broader clinical setting.     

MR angiography of steno-occlusive lesions of intracranial arteries: a comparative study between turbo MRA and conventional MRA]

PURPOSE: To compare the quality and diagnostic accuracy of images of intracranial steno-occlusive lesions obtained by conventional MRA and turbo MRA reconstructed using the zero-filled interpolation technique in the slice-select direction. MATERIALS AND METHODS: Eighteen patients with suspected steno-occlusive lesions of the intracranial arteries were studied with two types of three-dimensional time-of-flight angiography and conventional digital subtraction angiography. In total, 45 steno-occlusive lesions were quantitatively measured using calipers and correlated with DSA stenosis. A phantom that simulated vessels with stenosis was also imaged using the two types of MRA under the same conditions as those employed in the clinical study. RESULTS: Compared with conventional MRA, turbo MRA reduced the jaggedness of vessels and offered appearances more similar to those of DSA in the antero-posterior and lateral views. The severity of stenosis was classified into five grades based on the percentage of occlusion: not significant (0-24%), mild (25-49%), moderate (50-74%), severe (75-99%), and occlusive (100%). Neither turbo MRA nor conventional MRA showed any discrepancy from DSA above grade-1 stenosis. CONCLUSION: The advantage of turbo MRA is its ability to reduce the jaggedness of vessels on conventional MRA, and to simplify the recognition of vessel contours without prolonging acquisition time. Turbo MRA and conventional MRA have equally high diagnostic accuracy for steno-occlusive lesions.     

CT angiography in the assessment of carotid artery atherosclerosis

Objective: The aim of the study was to evaluate the ability of CT angiography (CTA) to detect atherosclerosis of the carotid arteries in comparison with 3D time-of-flight MR angiography (3D TOF MRA), using contrast angiography and intravascular ultrasound (IVUS) as a reference.Material and Methods: Contrast angiography and CTA were performed in 31 patients (mean age 65 years, range 45-79). The image quality was evaluated, atherosclerotic lesions were registered, and diameter stenosis degree was visually estimated from axial source images of CTA and 3D TOF MRA (21 patients), and results of interpretations were compared. The comparison of quantitative measurements was performed using IVUS as a reference.Results: Contrast angiography detected 51 lesions (mean diameter stenosis 50%, range 10-100%), and CTA detected all same lesions. CTA provided better image quality and consistency of image interpretation than 3D TOF MRA. IVUS verified 29 atherosclerotic lesions with a mean diameter stenosis of 35%, (range 4-40%). CTA yielded a sensitivity of 96% to 100% (≤10% or ≤20% diameter stenosis regarded as normal) for the detection of lesions with reference to IVUS.Conclusion: CTA seems feasible and accurate for the detection of atherosclerosis in carotid arteries.     

Multidirectional depiction of internal carotid arterial stenosis: three-dimensional time-of-flight MR angiography versus rotational and conventional digital subtraction angiography

PURPOSE: To evaluate whether and to what extent greater number of projection images obtained at three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography versus conventional digital subtraction angiography (DSA) causes overestimation of internal carotid arterial (ICA) stenosis. MATERIALS AND METHODS: DSA (two or three projections), rotational angiography (16 or 32 projections), and 3D TOF MR angiography (12 projections) were performed in 47 stenotic ICAs of 38 symptomatic patients. Two observers independently measured maximum stenosis, and the mean differences among MR angiography, DSA, and rotational angiography were compared. RESULTS: Three rotational and five MR angiograms were nondiagnostic. Seven MR angiograms of ICA stenoses showed a signal void and were excluded from analysis. On the remaining 32 angiograms, mean differences in maximum stenosis for observers 1 and 2, respectively, were 7% (95% CI: 3%, 12%) and 8% (95% CI: 3%, 13%) at MR angiography versus DSA and 2% (95% CI: -2%, 7%) and -1% (95% CI: -5%, 3%) at MR angiography versus rotational angiography. ICA stenosis was graded significantly higher at MR angiography versus DSA, whereas, it was not overestimated at MR angiography versus rotational angiography. The difference in maximum stenosis at MR angiography versus DSA was significantly different from that of MR angiography versus rotational angiography. CONCLUSION: Apparent overestimation of ICA stenosis at 3D TOF MR angiography versus conventional DSA may be partly explained by the greater number of projection images available at 3D TOF MR angiography.     

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.     

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。     

MR angiography at 3T versus digital subtraction angiography in the follow-up of intracranial aneurysms treated with detachable coils

BACKGROUND AND PURPOSE: Digital subtraction angiography (DSA) is used to follow-up intracranial aneurysms treated with detachable coils to identify recurrence and determine need for additional treatment. However, DSA is invasive and involves a small risk of neurologic complications. We assessed the feasibility and usefulness of 3D time-of-flight (TOF) MR angiography (MRA) performed at 3T compared with DSA for the follow-up of coil-treated intracranial aneurysms. METHODS: In a prospective study, 20 consecutive patients with 21 intracranial aneurysms treated with coils underwent DSA and nonenhanced and enhanced multiple overlapping thin-slab acquisition 3D TOF MRA at 3T on the same day at a mean follow-up of 6 months (range, 4-14 months) after coil placement. MRA images were evaluated for presence of artifacts, presence and size of aneurysm remnants and recurrences, patency of parent and branch vessels, and added value of contrast material enhancement. MRA and DSA findings were compared. RESULTS: Interobserver agreement of MRA was good, as was agreement between MRA and DSA. All three recurrences that needed additional treatment were detected with MRA. Minor disagreement occurred in four cases: three coil-treated aneurysms were scored on MRA images as having a small remnant, whereas on DSA images these aneurysms were occluded; the other aneurysm was scored on MRA images as having a small remnant, whereas on DSA images this was a small recurrence. Use of contrast material had no additional value. Coil-related MR imaging artifacts were minimal and did not interfere with evaluation of the occlusion status of the aneurysm. CONCLUSION: High-spatial-resolution 3D TOF MRA at 3T is feasible and useful in the follow-up of patients with intracranial aneurysms treated with coil placement.     

Imaging of aortoiliac arterial disease. Duplex ultrasound and MR angiography versus digital subtraction angiography

Purpose: To evaluate and compare the diagnostic accuracy of duplex ultrasound (US) and MR angiography (MRA) at 1.0 T in aortoiliac arterial disease using digital subtraction angiography (DSA) as the reference standard. In addition, a comparison of the 2D time-of flight (TOF) and 3D contrast-enhanced MRA (CE MRA) techniques was performed.Material and Methods: Prospectively, 39 patients with symptoms of lower-extremity arterial occlusive disease were examined using US, TOF MRA, CE MRA and DSA. Significant lesions (stenosis ≥50%) and occlusions were evaluated blindly for each method.Results: For all segments, the sensitivity for US, TOF MRA and CE MRA with regard to significant lesions was 0.72, 0.81 and 0.81, respectively, and the specificity for each was 0.97, 0.91 and 0.92, respectively. For significant lesions above the inguinal ligament the corresponding sensitivity was 0.84, 0.89 and 0.94 and the specificity 0.93, 0.82 and 0.73, respectively. The specificity was higher when the two MRA methods were combined. TOF MRA overgraded 7 segments as occluded. In most cases, the length of the occlusions was correctly determined on CE MRA, overestimated on TOF MRA and uncertain on US.Conclusion: Neither US nor MRA were sufficiently accurate to fully replace angiography. MRA was preferable to US as a non-invasive test when vascular intervention was contemplated. Although CE MRA was superior to TOF MRA, the most accurate results were achieved when the two methods were combined.     

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.     

Comparative assessment of helical CT-angiography, 2D TOF MR-angiography and 3D gadolinium enhanced MRA in aorto-iliac occlusive disease

PURPOSE: To compare helical CT-angiography (CTA) and two techniques of MR angiography (MRA) to conventional angiography in aorto-iliac occlusive disease. MATERIALS AND METHODS: The abdominal aorta and iliac arteries in 22 patients (4 for preoperative assessment of abdominal aortic aneurysm and 18 for peripheral vascular disease) were imaged using four techniques: digital subtraction angiography ("gold standard"), 2D TOF MR angiography, 3D Gd-enhanced MR angiography and helical CT angiography. Source (CTA and 2D TOF MRA) and MIPed images (after subtraction measures before and after gadolinium injection for 3D Gd-MRA) were reviewed. RESULTS: Sensitivity, specificity and accuracy for the detection of significant (>50%) stenosis and occlusion of aorto-iliac arteries were respectively: 38%, 89%, 77% for 2D TOF MRA; 75%, 71%, 72% for 3D Gd-MRA and 95%, 90%, 92% for CTA. Excluding the internal iliac arteries, results were 54%, 96%, 88% for 2D TOF MRA; 96%, 80%, 83% for 3D Gd-MRA and 92%, 93%, 95% for CTA. CONCLUSION: 3D Gd-MRA, a technique with potential for further improvement, is superior to 2D TOF MRA for detecting significant stenosis and occlusion of aorto-iliac arteries. Results at Gd-MRA are nearly similar to those at CTA (after excluding internal iliac arteries). Results at Gd-MRA are not affected by calcified plaque.     

脑血管狭窄与闭塞的MRA与DSA对照研究

目的：评价ＭＲＡ诊断脑血管狭窄与闭塞的价值又限度，并对假阳性、假阴性进行分析。材料与方法：对１４例患者的１２０根正常、狭窄与闭塞血管进行３Ｄ－ＴＯＦ ＭＯＴＳＡ ＭＲＡ和ＤＳＡ对照分析。结果：１４例１２０根血管ＭＲＡ与ＤＳＡ诊断相符合血管数为１０９根（９０．８％），ＭＲＡ对正常脑血管的敏感性、特异性、准确性分别为９１％、９０．３％、９０．８％；对狭窄血管分别为８３．３％、９２．１％、９０．８％；对     

Failing Hemodialysis Arteriovenous Fistula and Percutaneous Treatment: Imaging with CT, MRI and Digital Subtraction Angiography

Purpose: To evaluate failing hemodialysis arteriovenous fistulas with helical CT angiography (CTA), MR angiography (MRA), and digital subtraction angiography (DSA), and to compare the efficacy of the three techniques in detecting the number, location, grade, and extent of stenoses and in assessing the technical results of percutaneous transluminal angioplasty (PTA) and stenting. Methods: Thirteen patients with Brescia-Cimino arteriovenous fistula malfunction underwent MRA and CTA of the fistula and, within 1 week, DSA. A total of 11 PTAs were performed; in three cases an MR-compatible stent was placed. DSA served as the gold standard for comparison in all patients. The presence, site, and number of stenoses or occlusions and the technical results of percutaneous procedures were assessed with DSA, CTA, and MRA. Results: MRA underestimated a single stenosis in one patient; CTA and MRA did not overestimate any stenosis. Significant artifacts related to stent geometry and/or underlying metal were seen in MRA sequences in two cases. Conclusions: CT and MRI can provide information regarding the degree of vascular impairment, helping to stratify patients into those who can have PTA (single or multiple stenoses) versus those who require an operative procedure (occlusion). Conventional angiography can be reserved for candidates for percutaneous intervention.     

3D TRICKS MRA对颈动脉粥样硬化狭窄的诊断价值

目的：探讨3D TRICKS MRA对颈动脉粥样硬化狭窄的诊断价值。方法：对43例临床疑诊颈动脉粥样硬化狭窄的患者行2D TOF MRA和3D TRICKS MRA检查,其中31例同期行DSA检查,以颈总动脉法（CC法）计算狭窄率。结果：颈动脉闭塞2支,重度狭窄10支,中度狭窄31支,轻度狭窄25支,正常18支。2D TOF MRA、3D TRICKS MRA与DSA对照,显示狭窄部位均与DSA所示相符。2D TOF MRA高估狭窄程度6支,3D TRICKS MRA高估狭窄程度1支。以DSA为标准,2D TOF MRA诊断颈动脉狭窄的敏感度、特异度、诊断符合率分别为91.6%,85.7%,90.3%（K=0.737）;3D TRICKS MRA诊断颈动脉狭窄的敏感度、特异度、诊断符合率分别为97.9%,100%,98.4%（K=0.955）。两种方法对诊断颈动脉狭窄的敏感度、特异度和诊断符合率差异均具有统计学意义（P〈0.05）。结论：3D TRICKS MRA与DSA对评估颈动脉粥样硬化狭窄具有极好的一致性（K=0.955）,明显优于2D TOF MRA（K=0.737,P〈0.05）,是对颈动脉粥样硬化狭窄筛查、术前评估、术后随访的最佳检查方法,能基本替代DSA检查。     

CT angiography and MR angiography in the evaluation of carotid cavernous sinus fistula prior to embolization: a comparison of techniques

BACKGROUND AND PURPOSE: This study compared CT angiography (CTA), MR angiography (MRA), and digital subtraction angiography (DSA) in elucidating the size and location of carotid cavernous sinus fistulas (CCFs) before embolization treatment. METHODS: This was a retrospective study of 53 patients with angiographically confirmed CCF. All patients underwent pre- and postcontrast-enhanced CTA and DSA, and 50 patients also underwent MRA. Two neuroradiologists rated detectability of the fistula tract as "good," "moderate," or "poor" in source images obtained by using each procedure. The chi(2) test was used to compare the imaging modalities with respect to their ability to detect fistulas. RESULTS: CTA did not differ significantly from DSA (P = .155), and both CTA (P = .001) and DSA (P = .007) performed significantly better than MRA in the population as a whole. Differences in performance among the methods, however, depended upon the segmental location of the fistula along the internal carotid artery (ICA). CTA and MRA were similar in detection of CCFs in patients with a fistula at segment 3. CTA significantly outperformed MRA in patients with a fistula at segment 4, who accounted for approximately half of the population. CONCLUSIONS: CTA source imaging has proved itself as useful as DSA for detecting CCFs. Of the 2 noninvasive techniques, CTA performed better than MRA in the population as a whole and in most patients whose fistula was located at segment 4 or 5 of the ICA.     

Non-invasive assessment of epiaortic vessels. Comparison of magnetic resonance angiography with gadolinium, spiral computerized tomography angiography, and digital angiography

PURPOSE: The aim of the study was to compare gadolinium-enhanced MRA (Gd-MRA), Computed Tomography angiography (CTA) and digital subtraction angiography (DSA) in the evaluation of carotid stenosis. MATERIAL AND METHODS: Thirty patients with US-proven internal carotid artery stenosis over 50%, underwent Gd-MRA, CTA and DSA. Gd-MRA was acquired using the keyhole technique. RESULTS: The overall agreement was 90% for Gd-MRA and 93% for CTA. Gd-MRA and CTA overestimated 5 and 4 cases of mild stenosis and 1 case each of moderate stenosis, respectively. Gd-MRA better delineated ulcerated plaques, tandem lesions and pseudo-occlusions. DISCUSSION AND CONCLUSIONS: Because of the high speed acquisition breath-hold is no longer necessary for Gd-MRA and more delayed phases were analysed when necessary. The main limitation of Gd-MRA was represented by insufficient volume coverage that allowed the visualisation of supraaortic vessels from the arch only in 57% of the cases. Calcified plaques were very well detected by CTA and not by Gd-MRA. In our experience Gd-MRA represents the second step non invasive tool in patients with US-proven carotid stenosis. This leads to avoid conventional angiography in most cases.     

Time-of-Flight MR Angiography of Carotid Artery Stenosis: Does a Flow Void Represent Severe Stenosis?

BACKGROUND AND PURPOSE: Time-of-flight (TOF) magnetic resonance angiography (MRA) is commonly used to visualize the carotid arteries; however, flow void artifacts can appear. Our purpose was to determine the frequency and diagnostic meaning of flow voids by using real patient data, as part of a larger study of MRA compared with the criterion standard, digital subtraction angiography (DSA). METHODS: In 1997-2000, 390 consecutive patients with sonographic findings suggestive of carotid artery stenosis were included in this study. All patients subsequently underwent three-dimensional (3D) TOF MRA and conventional DSA. The frequency of flow void artifacts on 3D TOF MRA images were compared with stenosis measurements on DSA images. RESULTS: We recorded 107 flow voids (16%) during 3D TOF MRA of 662 carotid arteries. DSA images were available for comparison in 102 cases. The median percentage of stenosis in this subgroup of flow voids on MRA images was 80%, compared with measurements on DSA images according to the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria. Stenoses ranged from 36% to 100% (occlusion). Three flow voids (2.9%) were in the 0-49% range; 11 (10.8%), in the 50-69% range; and 86 (84.3%), in the 70-99% range. Two flow voids (2.0%) represented occlusions. The positive predictive value of a flow void artifact for the presence of severe (70-99%) stenosis was 84.3% (95% CI: 77.3%, 91.4%). CONCLUSION: Flow void artifacts represented severe stenosis in most of the arteries. According to our data, the assumption that flow voids on 3D TOF MRA images represent severe stenosis is justified.