Dual-energy CT head bone and hard plaque removal for quantification of calcified carotid stenosis: utility and comparison with digital subtraction angiography

We evaluated quantification of calcified carotid stenosis by dual-energy (DE) CTA and dual-energy head bone and hard plaque removal (DE hard plaque removal) and compared the results to those of digital subtraction angiography (DSA). Eighteen vessels (13 patients) with densely calcified carotid stenosis were examined by dual-source CT in the dual-energy mode (tube voltages 140 kV and 80 kV). Head bone and hard plaques were removed from the dual-energy images by using commercial software. Carotid stenosis was quantified according to NASCET criteria on MIP images and DSA images at the same plane. Correlation between DE CTA and DSA was determined by cross tabulation. Accuracies for stenosis detection and grading were calculated. Stenosis could be evaluated in all vessels by DE CTA after applying DE hard plaque removal. In contrast, conventional CTA failed to show stenosis in 13 out of 18 vessels due to overlapping hard plaque. Good correlation between DE plaque removal images and DSA images was observed (r ² = 0.9504) for stenosis grading. Sensitivity and specificity to detect hemodynamically relevant (>70%) stenosis was 100% and 92%, respectively. Dual-energy head bone and hard plaque removal is a promising tool for the evaluation of densely calcified carotid stenosis.     

数字减影CT血管成像与三维数字减影血管造影(DSA)技术检测颅内动脉瘤的比较研究

目的评价数字减影CT血管成像技术对颅内动脉瘤诊断的准确度,将三维旋转数字减影血管造影(DSA)技术作为参考标准,进行单中心大队列样本的研究。材料与方法本研究免除机构审查委员会批准,因为它本质上是回顾性的     

Subtraction CT angiography for evaluation of intracranial aneurysms: comparison with conventional CT angiography

The purpose of our study was to compare the diagnostic performance of subtraction computed tomography angiography (CTA) with conventional nonsubtracted CTA and digital subtraction angiography (DSA) for the detection of intracranial aneurysms. A total of 76 patients underwent both subtraction CTA and conventional CTA for the detection and therapy planning of suspected intracranial aneurysms. Subtraction and conventional CTA images were independently assessed by two readers in a blinded manner. The possibility of endovascular treatment or surgical clipping was also assessed based on information provided by CT angiograms alone. In 64 patients, 75 aneurysms were present on DSA. On a per-aneurysm basis, the sensitivity of subtraction CTA was 98.6% for reader 1, and 100% for reader 2. However, sensitivity of conventional CTA was 94.6% for reader 1, and 93.3% for reader 2. Therapeutic decisions could be made regarding 63 patients based on information provided by subtraction CTA images. However, conventional CTA provided sufficient information to make this decision for 55 patients. Conventional CTA has limited sensitivity in detecting very small aneurysms as well as aneurysms adjacent to bone. Subtraction CTA performed on a 64-row multidetector CT is an accurate and promising diagnostic tool that seems to be equivalent to 2D DSA for the detection and pretreatment planning of intracranial aneurysms.     

Subtracted 3D CT angiography for evaluation of internal carotid artery aneurysms: comparison with conventional digital subtraction angiography

BACKGROUND AND PURPOSE: 3D computed tomographic angiography (3DCTA) has been used recently for the evaluation of intracerebral aneurysms, but it is difficult to use this technique to visualize aneurysms near the base of the skull because of the presence of bone. Subtracted 3DCTA could replace digital subtraction angiography (DSA) for evaluation of aneurysms near the base of the skull if the 2 methods were to give similar results. The aim of this study was to compare the evaluation of aneurysms of the internal carotid artery (ICA) near the base of the skull by subtracted 3DCTA and DSA. METHODS: CTA and DSA were obtained in 25 patients with unruptured aneurysms of the ICA. To create subtracted 3DCTA images, we used a volume subtraction (VS) method, wherein nonenhanced volume data are subtracted from enhanced volume data. CTA and DSA were reviewed by 2 neuroradiologists who performed the detection and characterization of aneurysms of the ICA by using 2D multiplanar reformatted (MPR) and VS- and nonsubtracted (NS)-3DCTA images with volume rendering techniques. RESULTS: DSA detected 29 aneurysms in the 25 patients. VS-3DCTA detected all 29 aneurysms in the 25 patients and was equivalent to DSA for evaluating their characteristics (location, size, and direction). NS-3DCTA detected 19 (1 cavernous, 4 ophthalmic, 1 superior hypophyseal, 7 posterior communicating, and 6 anterior choroidal artery) of these 29 aneurysms, but it could not characterize ophthalmic and superior hypophyseal artery aneurysms because they were only partly visible on NS-3DCTA because of bony structures. 2D-MPR images detected all but the small aneurysms (24 of 29 detected). VS-3DCTA and 2D-MPR could visualize all branching arteries (ophthalmic, posterior communicating, and anterior choroidal) detected by DSA, but NS-3DCTA could not visualize ophthalmic arteries because of the presence of bony structures. CONCLUSION: VS-3DCTA can be used as an alternative to DSA for preoperative examination of aneurysms near the skull base, where it provides equivalent identification and characterization.     

3.0T时间飞跃法MRA诊断颅内动脉瘤-与DSA对照

目的评价3.0T时间飞跃法磁共振血管成像(3.0TTOFMRA)对颅内动脉瘤的诊断价值。方法对34例临床提示颅内动脉瘤患者前瞻性行3.0TTOFMRA及脑血管DSA检查。所有图像由3名医师分成2组在工作站上进行读片。第1组由2名高年资神经影像组医师分别独立阅读重建的最大密度投影(MIP)图像;第2组由1名高年资神经影像组医师同时阅读MIP和原始数据图像(sourceimage)。以DSA诊断结果作为标准,评价3.0TTOFMRA诊断颅内动脉瘤的灵敏度、特异度及正确率。结果DSA共检测20枚动脉瘤(19例),其中颈内动脉7例,前交通动脉5例,后交通动脉5例,大脑前、中动脉各1例。TOFMRA总体诊断灵敏度、特异度、正确率分别为94.8%、89.4%和91.4%。第2组的诊断有效性最高,两组间诊断阳性率差异无统计学意义(χ2=0.242,P>0.05和χ2=0.172,P>0.05)。结论3.0TTOFMRA作为一种快速、无创的影像检查方法,能够很好显示颅内动脉瘤。MIP结合Source图像可提高3.0TTOFMRA诊断的准确性。     

Renal artery stenosis: evaluation with intravenous digital subtraction angiography

The ability of diagnostic intravenous digital subtraction angiography (IVDSA) to demonstrate the degree of renal artery stenosis was compared with that of intraarterial angiography in 45 patients with 92 arteries. Stenotic lesions on both IVDSA and intraarterial studies were classified as normal (0% stenosis), minor (less than 50%), low grade (50%-80%), and high grade (80%-99%). There was agreement about the degree of stenosis in 90% of the cases. IVDSA grading was correct in 94% of atheromatous lesions and in 56% of the fibromuscular dysplastic lesions. In the high-grade atheromatous lesions, the degree of stenosis was slightly overestimated on IVDSA studies in 22.5% of the cases. In fibromuscular dysplasia, stenosis was underestimated in 33% of the cases.     

Diagnostic accuracy of CT angiography with matched mask bone elimination for detection of intracranial aneurysms: comparison with digital subtraction angiography and 3D rotational angiography

BACKGROUND AND PURPOSE: Our aim was to determine the diagnostic accuracy of multisection CT angiography combined with matched mask bone elimination (CTA-MMBE) for detection of intracranial aneurysms compared with digital subtraction angiography (DSA) and 3D rotational angiography (3DRA).MATERIALS AND METHODS: Between January 2004 and February 2006, 108 patients who presented with clinically suspected subarachnoid hemorrhage underwent both CTA-MMBE and DSA for diagnosis of an intracranial aneurysm. Two neuroradiologists, independently, evaluated 27 predefined vessel locations in the CTA-MMBE images for the presence of an aneurysm. After consensus, diagnostic accuracy of CTA was calculated per predefined location and per patient. Interobserver agreement was calculated with κ statistics.RESULTS: In 88 patients (81%), 117 aneurysms (82 ruptured, 35 unruptured) were present on DSA. CTA-MMBE detected all ruptured aneurysms except 1. Overall specificity, sensitivity, positive predictive value, and negative predictive value of CTA-MMBE were 0.99, 0.90, 0.98, and 0.95 per patient and 0.91, 1.00, 0.97, and 0.99 per location, respectively. Sensitivity was 0.99 for aneurysms ≥3 mm and 0.38 for aneurysms <3 mm. Interobserver agreement for aneurysm detection was excellent (κ value of 0.92 per location and 0.80 per patient).CONCLUSION: CTA-MMBE is accurate in detecting intracranial aneurysms in any projection without overprojecting bone. CTA-MMBE has limited sensitivity in detecting very small aneurysms. Our data suggest that DSA and 3DRA can be limited to the vessel harboring the ruptured aneurysm before endovascular treatment, after detection of a ruptured aneurysm with CTA.

In current clinical practice, CT angiography (CTA) is the most frequently used noninvasive diagnostic tool for detection of intracranial aneurysms in the acute setting.^1–8 However, detection of intracranial aneurysms by CTA is limited because axial source section evaluation is tedious and 3D visualization is hampered by overprojecting bone, especially in the region of the skull base.^2,9–13 Several methods to remove bone, such as subtraction and manual or automated bone editing, have been developed.^7,8,14–19 Drawbacks of these methods are the complexity of use, dependence on the user, or high dose of radiation.Matched mask bone elimination (MMBE) is a relatively new technique to remove bone from CTA source images (CTA-MMBE) in an automatic and user-independent way with little additional radiation dose.^20–22 In CTA-MMBE, a second nonenhanced low-dose scan (about a quarter of the radiation dose of a regular CTA) is used to identify bony structures that can subsequently be masked in the CTA scan.Digital subtraction angiography (DSA) is the gold standard for detection of intracranial aneurysms. Extension of DSA with 3D rotational angiography (3DRA) can further improve detection of intracranial aneurysms that may be obscured by overprojecting vessels.^23–25 The advantages of DSA over CTA are superior spatial and contrast resolution, no interference of bony structures, and the possibility to perform direct endovascular interventions.^26,27 However, DSA is an invasive technique with a small but significant risk of neurologic complications, estimated to occur in 0.3%–1.8% of patients.^28,29The purpose of this study was to determine the diagnostic accuracy of CTA-MMBE for detection of intracranial aneurysms in a large patient population with clinically suspected subarachnoid hemorrhage (SAH) with DSA and 3DRA as reference standards.     

Magnetic resonance angiography of intracranial aneurysms: comparison with intra-arterial digital subtraction angiography

Summary Magnetic resonance angiography (MRA) with flow rephased gradient-echo sequences is a new non-invasive method for vascular imaging. We compared MRA and intra-arterial digital subtraction angiography in 18 patients with intracranial aneurysms to test whether MRA presently provides an alternative to cerebral angiography for the diagnosis of these anomalies. MRA showed 19 of the 22 aneurysms detected (86.4%). However, problems, especially with turbulent or slow flow, resulted in 6 studies (27.3%) with limited and 2 with questionable demonstration of an aneurysm, and 1 false negative study. At present, MRA is definitely inferior to angiography for the demonstration of intracranial aneurysms, due to its lower resolution and other limitations.     

Intracranial vascular stenosis and occlusive disease: evaluation with CT angiography, MR angiography, and digital subtraction angiography

BACKGROUND AND PURPOSE: Although digital subtraction angiography (DSA) provides excellent visualization of the intracranial vasculature, it has several limitations. Our purpose was to evaluate the ability of helical CT angiography (CTA) to help detect and quantify intracranial stenosis and occlusion compared with DSA and MR angiography (MRA). METHODS: Twenty-eight patients underwent CTA, DSA, and 3D time-of-flight (TOF) MRA for suspected cerebrovascular lesions. All three studies were performed within a 30-day period. Two readers blinded to prior estimated or calculated stenoses, patient history and clinical information examined 672 vessel segments. Lesions were categorized as normal (0-9%), mild (10-29%), moderate (30-69%), severe (70-99%), or occluded (no flow detected). DSA was the reference standard. Unblinded consensus readings were obtained for all discrepancies. RESULTS: A total of 115 diseased vessel segments were identified. After consensus interpretation, CTA revealed higher sensitivity than that of MRA for intracranial stenosis (98% versus 70%, P < .001) and occlusion (100% versus 87%, P = .02). CTA had a higher positive predictive value than that of MRA for both stenosis (93% versus 65%, P < .001) and occlusion (100% versus 59%, P < .001). CTA had a high interoperator reliability. In 6 of 28 patients (21%), all 6 with low-flow states in the posterior circulation, CTA was superior to DSA in detection of vessel patency. CONCLUSION: CTA has a higher sensitivity and positive predictive value than MRA and is recommended over TOF MRA for detection of intracranial stenosis and occlusion. CTA has a high interoperator reliability. CTA is superior to DSA in the evaluation of posterior circulation steno-occlusive disease when slow flow is present. CTA results had a significant effect on patient clinical management.     

Detection and evaluation of intracranial aneurysms with 16-row multislice CT angiography: comparison with conventional angiography

The aim of our study was to compare multidetector row computed tomography (CT) angiography (MDCTA) with digital subtraction angiography (DSA) in the detection and characterization of intracranial aneurysms. Between September 2005 and May 2007, 55 consecutive patients with suspected intracranial aneurysms underwent conventional DSA and MDCTA. Thirty-two women and 23 men were enrolled in the study. The mean patient age was 54 (range = 26–79 years). All MDCTA and DSA images were independently evaluated on a workstation by two radiologists, who had 8 and 6 years of experience in CT vascular imaging and angiography. Using DSA as the gold standard, the sensitivity and specificity of CT angiography was calculated for each reader with 95% confidence intervals. The sensitivity was also calculated for aneurysms smaller than 3 mm with 95% confidence intervals. The agreement between the readers for detecting aneurysms was calculated using kappa statistics. A kappa statistic greater than 0.75 was considered an excellent agreement beyond chance, a kappa statistic of 0.4–0.75, fair to good agreement, and a kappa statistic less than 0.4, poor agreement. At DSA, 64 aneurysms were present in 50 patients involved in the study; seven patients had two aneurysms each, and four patients had three aneurysms each. In five patients, no aneurysm was detected by using MDCTA and DSA, and evaluations were considered as true negative by MDCTA. These five patients also had negative findings at repeat DSA. For readers 1 and 2, the sensitivity of MDCT in detecting aneursyms were 96.9% (95% CI = 89.3–99.1%; 62 of 64) and 98.4 % (95% CI = 91.7–99.7%; 63 of 64), respectively. The spescificity was100% (95% CI = 99.7–100%; 1,256 of 1,256) for both readers. The kappa value indicating interobserver agreement was in the category of excellent (kappa = 0.99 (95% CI = 0.97–1). Regarding the aneurysms smaller than 3 mm, for readers 1 and 2, the sensitivities were 84.6% (95% CI = 57.8–95.7%; 11 of 13) and 92.3% (95% CI = 66.7–98.6; 12 of 13), respectively. MDCTA is accurate in the detection and characterization of intracranial aneurysms and can be used as a reliable alternative imaging technique to DSA. A strategy of using CT angiography as the primary method, with DSA reserved for any cases of uncertainty, appears safe and reliable.     

Postoperative multidetector computed tomography angiography after aneurysm clipping: comparison with digital subtraction angiography

OBJECTIVES: To evaluate the usefulness of multidetector computed tomography angiography (MDCTA) as a noninvasive diagnostic modality for the detection of aneurysm remnants after clipping of intracranial aneurysms. METHODS: Thirty-eight patients who had aneurysm clipping and had undergone MDCTA and digital subtraction angiography (DSA) were enrolled in this study. In 16 of the 38 patients, MDCTA was performed with 16-channel MDCTA, in 20 patients with 4-channel MDCTA, and in 2 with both. Two neuroradiologists evaluated the image quality of MDCTA with a 3-point rating scale and the presence of the residual aneurysm sac with a 5-point rating scale. Receiver operating characteristic analysis was used to measure the diagnostic performance of MDCTA. RESULTS: Forty-nine surgically clipped aneurysms were evaluated in this study. The overall diagnostic accuracy of MDCTA was 88.1% (95% confidence interval: 0.761-0.954). The ability of 16-channel MDCTA to discriminate between surgical clips and parent vessels was superior to that of 4-channel MDCTA (P=0.005). CONCLUSION: Multidetector computed tomography angiography is a valuable noninvasive diagnostic modality for the assessment of aneurysm remnants in patients after aneurysm clipping.     

Fibromuscular dysplasia of renal arteries: comparison of intravenous digital subtraction angiography with conventional angiography

Intravenous digital subtraction angiography (IV-DSA) was compared with conventional arteriography (CA) in 14 patients with fibromuscular dysplasia (FMD) of at least one renal artery. IV-DSA identified 29 of the 34 renal arteries detected by CA. A diagnostic quality IV-DSA examination was obtained in 23 of 29 renal arteries (78%). In adequately imaged renal arteries, IV-DSA correctly identified 12 of 20 FMD renal arteries, misdiagnosed 8 FMD renal arteries as normal and correctly identified 3 normal renal arteries. These poor results, due to poor spatial resolution and subtraction artifacts inherent in the IV-DSA system, warrant careful interpretation of negative examinations and further evaluation of high risk patients.