Intracranial aneurysms: evaluation by MR angiography

The purpose of this study was to compare the accuracy of a volume gradient-echo MR angiography (MRA) technique with that of intraarterial digital subtraction angiography (IA DSA) in the identification of intracranial aneurysms. The intracranial vasculature was examined in 47 patients by MRA and compared with IA DSA findings in 19 of these patients who had saccular or giant intracranial aneurysms. The remaining 28 patients, in whom no aneurysm was found, served as a control group. MRA was performed with the use of a velocity-compensated gradient-echo sequence (TR = 40-50/TE = 7-15) with a 15 degrees flip angle. The sensitivity and specificity were calculated for the evaluation of the cine 3D reconstructions (cine MRA) only, cine MRA + inspection of the individual partitions, and cine MRA + individual partitions + spin-echo studies. Of 21 aneurysms, of which three were missed in two patients, the sensitivity varied from 67% for cine MRA only to 86% for the cine MRA + partitions + spin-echo studies; of the 19 patients, among whom it was assumed that the diagnosis of any one aneurysm in a patient would lead to angiography and detection of additional aneurysms, the sensitivity varied from 73% for the cine MRA only to 95% for the cine MRA + partitions + spin-echo studies. The results of this study suggest that MRA can define the circle of Willis sufficiently to allow detection of intracranial aneurysms as small as 3-4 mm. MRA holds promise as a truly noninvasive screening examination of intracranial vasculature in patients at risk for aneurysms.     

Intracranial aneurysms: evaluation by MR angiography

The purpose of this study was to compare the accuracy of a volume gradient-echo MR angiography (MRA) technique with that of intraarterial digital subtraction angiography (IA DSA) in the identification of intracranial aneurysms. The intracranial vasculature was examined in 47 patients by MRA and compared with IA DSA findings in 19 of these patients who had saccular or giant intracranial aneurysms. The remaining 28 patients, in whom no aneurysm was found, served as a control group. MRA was performed with the use of a velocity-compensated gradient-echo sequence (TR = 40-50/TE = 7-15) with a 15 degree flip angle. The sensitivity and specificity were calculated for the evaluation of the cine 3D reconstructions (cine MRA) only, cine MRA + inspection of the individual partitions, and cine MRA + individual partitions + spin-echo studies. Of 21 aneurysms, of which three were missed in two patients, the sensitivity varied from 67% for cine MRA only to 86% for the cine MRA + partitions + spin-echo studies; of the 19 patients, among whom it was assumed that the diagnosis of any one aneurysm in a patient would lead to angiography and detection of additional aneurysms, the sensitivity varied from 73% for the cine MRA only to 95% for the cine MRA + partitions + spin-echo studies. The results of this study suggest that MRA can define the circle of Willis sufficiently to allow detection of intracranial aneurysms as small as 3-4 mm. MRA holds promise as a truly noninvasive screening examination of intracranial vasculature in patients at risk for aneurysms.     

Intracranial aneurysms and vascular malformations: comparison of time-of-flight and phase-contrast MR angiography

Twenty-seven patients with 14 aneurysms and 17 vascular malformations were each examined with both time-of-flight (TF) and phase-contrast (PC) magnetic resonance angiography of the head. Three-dimensional (3D) PC imaging depicted the patent lumen of the aneurysms, while 3D TF imaging depicted the patent lumen and a subacute thrombus if present. The 3D PC techniques were superior to 3D TF methods in depicting aneurysms larger than 15 mm. PC angiography allowed velocity resolution of vascular lesions and yielded functional flow information by directly depicting collateral flow to vascular lesions. Artifacts present on TF images were due to substances with short T1, hemosiderin, and surgical clips. Artifacts present on PC images were due to flow-related aliasing. The results showed that PC techniques have specific advantages over TF techniques, including identification of large aneurysms, velocity resolution of vascular lesions, depiction of flow direction about the circle of Willis, and less degradation by artifacts.     

颅内动脉瘤双源CT血管成像与常规和三维DSA结果的比较

目的 评价双源CT血管成像(DSCTA)在颅内动脉瘤诊断中的价值,并与常规和三维旋转DSA进行对照研究.方法 95例自发性蛛网膜下腔出血患者同时进行了DSCTA和DSA检查,用2种方法分别评价动脉瘤的检出率、形态、长轴及动脉瘤瘤颈/短轴(N/D)比值.动脉瘤N/D值比较采用配对t检验,长轴比较采用两相关样本的非参数检验.结果 95例患者,DSA在63例患者中检出67个动脉瘤,DSCTA在60例患者中检出64个动脉瘤,32例患者未检测到动脉瘤.DSCrA检测动脉瘤总的诊断敏感性、特异性、阳性预测值及阴性预测值分别为94.2%、100.0%、100.0%、91.4%.DSCTA对长径33 nnn动脉瘤的检出率与DSA一致,其诊断敏感性、特异性均为100%;长径＜3 mm动脉瘤的诊断敏感性和特异性分别为80.O%和100.0%.DSA与DSCTA所测动脉瘤N/D比值分别为0.46±0.14、0.51±0.18,差异无统计学意义(t=3.20,P＞0.05);长轴中位数分别为4.9、4.8 mm,差异也无统计学意义(Z=-1.309,P＞0.05).结论 DSCTA在诊断颅内动脉瘤方面与常规和三维旋转DSA相比有很高的敏感性和特异性.提高了小动脉瘤的检出率,可作为一种无创性的常规筛查方法.     

Intracranial aneurysms at MR angiography: effect of computer-aided diagnosis on radiologists' detection performance

PURPOSE: To retrospectively evaluate the effect of computer-aided detection (CAD) on radiologists' performance in detection of intracranial aneurysms with magnetic resonance (MR) angiography. MATERIALS AND METHODS: The institutional review board approved this study and did not require patient informed consent. Fifty maximum intensity projection MR angiograms in 50 patients were used for observer performance study. The group included 22 patients (age range, 43-86 years; mean, 60.2 years; 6 men and 16 women) with intracranial aneurysms and 28 patients (age range, 32-80 years; mean, 58.8 years; 10 men and 18 women) without aneurysms. The MR angiograms were obtained with three-dimensional time-of-flight 1.5-T MR imaging. Fifteen radiologists, including eight neuroradiologists and seven general radiologists, participated in the observer performance test. They interpreted the angiograms first without and then with the aid of the computer output by using an automated computerized scheme. The observers' performance without and with the computer output was evaluated with receiver operating characteristic analysis. RESULTS: For all 15 observers, average area under the receiver operating characteristic curve (A(z)) value for detection of aneurysms was increased significantly from 0.931 to 0.983 (P = .001) when they used the computer output. A(z) values for general radiologists and neuroradiologists increased from 0.894 to 0.983 (P = .022) and from 0.963 to 0.984 (P = .014), respectively. Improvement in the performance of general radiologists in terms of the A(z) value was much greater than that of neuroradiologists. Performance of general radiologists with CAD (A(z) = 0.983) slightly exceeded that of neuroradiologists without CAD (A(z) = 0.963) (P = .048). CONCLUSION: CAD improved neuroradiologists' and general radiologists' performance for detection of intracranial aneurysms with MR angiography; improvement was greater for general radiologists than it was for neuroradiologists.     

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.     

Intracranial aneurysms: evaluation in 200 patients with spiral CT angiography

The goal of this study was to assess the usefulness of spiral CT angiography (CTA) with three- dimensional reconstructions in defining intracranial aneurysms, particularly around the Circle of Willis. Two hundred consecutive patients with angiographic and/or surgical correlation were studied between 1993 and 1998, with CTA performed on a GE HiSpeed unit and Windows workstation. The following clinical situations were evaluated: conventional CT suspicion of an aneurysm; follow-up of treated aneurysm remnants or of untreated aneurysms; subarachnoid haemorrhage (SAH) and negative angiography; family or past aneurysm history; and for improved definition of aneurysm anatomy. Spiral CTA detected 140 of 144 aneurysms, and an overall sensitivity of 97 %, including 30 of 32 aneurysms 3 mm or less in size. In 38 patients with SAH and negative angiography, CTA found six of the seven aneurysms finally diagnosed. There was no significant artefact in 17 of 23 patients (74 %) with clips. The specificity of CTA was 86 % with 8 false-positive cases. Spiral CTA is very useful in demonstrating intracranial aneurysms. Received: 13 April 1999 Revised: 22 March 2000 Accepted: 3 May 2000     

Multi-section CT angiography for detection of cerebral aneurysms

BACKGROUND AND PURPOSE: Multi-section CT has great potential for use in vascular studies. Our purpose was to determine the accuracy of multi-section CT angiography in detecting cerebral aneurysms compared with digital subtraction angiography or surgery. METHODS: One hundred consecutive patients who underwent multi-section CT angiography and either digital subtraction angiography or surgery were included in the study. Multi-section CT angiography and digital subtraction angiography results were evaluated independently by different neuroradiologists who performed aneurysm detection, quantitation, and characterization by using 2D multiplanar reconstructions, 3D maximum intensity projection, and volume-rendered techniques. RESULTS: When using intra-arterial digital subtraction angiography or surgery, 113 aneurysms (true positives and false negatives) were detected in 83 of the 100 patients. A total of 106 aneurysms (true positives) were confirmed by using digital subtraction angiography or surgery, or both. Seven aneurysms were missed when using multi-section CT angiography. Eight aneurysms were not confirmed by digital subtraction angiography and were considered to be false positive evaluations. The sensitivity for detecting aneurysms < 4 mm, 4 to 10 mm, and > 10 mm on a per-aneurysm basis was 0.84 (95% confidence interval: 0.72, 0.92), 0.97 (95% confidence interval: 0.91, 0.99), and 1.00 (95% confidence interval: 0.88, 1.00), respectively. The sensitivity, specificity, and accuracy of multi-section CT angiography for detecting aneurysms on a per-patient basis were 0.99 (95% confidence interval: 0.96, 1.00), 0.88 (95% confidence interval: 0.69, 0.94), and 0.98 (95% confidence interval: 0.95, 1.00), respectively. CONCLUSION: Multi-section CT angiography has a high sensitivity in detecting aneurysms (especially aneurysms > 3 mm). However, CT angiography is currently not sensitive enough to replace digital subtraction angiography.     

Intracranial granulocytic sarcoma: CT, MR, and angiography.

Granulocytic sarcoma is a rare, solid tumor composed of immature granulocytes usually found in association with systemic leukemia in younger patients. We present a case of granulocytic sarcoma occurring in an elderly female with no evidence of systemic leukemia. Computed tomography, MR (with and without Gd-DTPA), and angiography showed features commonly found in meningiomas.     

Intracranial MR angiography: a direct comparison of three time-of-flight techniques.

During the past few years, several time-of-flight MR angiographic techniques have been described for rapid, reliable, noninvasive vascular evaluation. This investigation was performed to directly compare three time-of-flight methods in imaging the intracranial vasculature: a single-volume method, a sequential two-dimensional slice technique, and a technique using the sequential acquisition of multiple thin volumes. Thirty-two normal volunteers were imaged, and direct comparisons of the three techniques were performed in 20 subjects. Analysis of the resulting images revealed optimal depiction of large vessels with the single-volume and multiple thin-volume methods, small vessels with the multiple thin-volume technique, and venous structures with the sequential two-dimensional slice acquisition. The effects of progressive spin saturation in time-of-flight MR angiography are discussed along with the individual benefits and disadvantages of each method. We conclude that the diagnostic value of intracranial time-of-flight MR angiography can be maximized through tailoring the angiographic method to the suspected abnormality based on the requirements for spatial resolution and slow-flow sensitivity, as suggested by the clinical history or prior imaging studies.     

Aortoiliac and renal arteries: prospective intraindividual comparison of contrast-enhanced three-dimensional MR angiography and multi-detector row CT angiography

PURPOSE: To compare contrast material-enhanced three-dimensional (3D) magnetic resonance (MR) angiography and multi-detector row computed tomographic (CT) angiography in the same patients for assessment of the aortoiliac and renal arteries, with digital subtraction angiography (DSA) as the standard of reference. MATERIALS AND METHODS: DSA, 3D MR angiography, and multi-detector row CT angiography were performed in 46 consecutive patients. A total of 769 arterial segments were analyzed for arterial stenosis by using a four-point grading system. Aneurysmal changes were noted. The time required for performing 3D reconstructions and image analysis of both MR and CT data sets was measured. Patient acceptance for each modality was assessed with a visual analogue scale. Statistical analysis of data was performed. RESULTS: Sensitivity of MR angiography for detection of hemodynamically significant arterial stenosis was 92% for reader 1 and 93% for reader 2, and specificity was 100% and 99%, respectively. Sensitivity of CT angiography was 91% for reader 1 and 92% for reader 2, and specificity was 99% and 99%, respectively. Differences between the two modalities were not significant. Interobserver and intermodality agreement was excellent (kappa = 0.88-0.90). The time for performance of 3D reconstruction and image analysis of CT data sets was significantly longer than that for MR data sets (P <.001). Patient acceptance was best for CT angiography (P =.016). CONCLUSION: There is no statistically significant difference between 3D MR angiography and multi-detector row CT angiography in the detection of hemodynamically significant arterial stenosis of the aortoiliac and renal arteries.     

颅内动脉瘤320排CTA与DSA对照分析

目的 探讨320排CTA对颅内动脉瘤诊断的临床应用价值.方法 收集2010-04-2011-03期间行320排CTA和DSA检查的颅内动脉瘤患者33例.将CTA图像质量按颅底骨质残留及血管显示情况分为4个等级,再以DSA所见为对照,分析320排CTA诊断颅内动脉瘤的敏感性及粗符合率.结果 33例经320排CTA检出颅内动脉瘤30例33个、动静脉畸形(AVM)2例、颅内动脉瘤合并AVM 1例;经DSA证实有颅内动脉瘤30例33个、AVM 3例,其中动脉瘤"假阳性"1例;有22例行手术治疗.320排CTA诊断颅内动脉瘤敏感性为100%,粗符合率为97.0%.结论 与DSA比较,320排CTA诊断颅内动脉瘤有较高的敏感性及粗符合率,在术前筛查方面具有广泛的临床应用前景.     

Intracranial aneurysms: detection with three-dimensional CT angiography with volume rendering--comparison with conventional angiographic and surgical findings

PURPOSE: To assess the diagnostic accuracy of three-dimensional (3D) computed tomographic (CT) angiography for intracranial aneurysms. MATERIALS AND METHODS: The 3D CT angiograms obtained in 49 patients with or without intracranial aneurysms were evaluated by four blinded observers. Results were compared with findings at conventional angiography or surgery. A volume-rendering method was used, and 13 images obtained in different directions were reviewed in each study. The diameter of aneurysms was divided into four sizes: large, greater than 13 mm; medium, 5-12 mm; small, 3-4 mm; and very small, less than 3 mm. Results were also evaluated by means of receiver operating characteristic analysis. RESULTS: At conventional angiography, 47 aneurysms, including 14 less than 3 mm, were depicted in 35 patients. The mean sensitivity of CT angiography for very small aneurysms was 64%; small, 83%; medium, 95%; and large, 100%. Some very small aneurysms that were not depicted at conventional angiography were depicted at CT angiography, and one was proved at surgery. CONCLUSION: CT angiography has good sensitivity for depiction of intracranial aneurysms 3 mm or larger and relatively good sensitivity for aneurysms less than 3 mm. CT angiography may be a noninvasive technique for detection of asymptomatic unruptured or ruptured aneurysms.