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.     

Spiral CT angiography and surgical correlations in the evaluation of intracranial aneurysms

We investigated the accuracy of spiral computed tomography angiography (CTA) in the detection and study of intracranial aneurysms by comparing CTA with selective angiograms and surgical findings. Twenty-six patients (9 men and 17 women; mean age 53.1 ± 1.8 years) with suspected intracranial aneurysms were submitted to CTA (1- to 2-mm slices, pitch 1:1, 24 s, RI = 1) after a conventional CT examination showing subarachnoid hemorrhage (SAH) in 19 cases and during neuroradiological investigations performed for other reasons in 7 cases. One hundred twenty to 150 ml iodate contrast agent (0.3–0.4 gI/ml) were injected intravenously at 5 ml/s rate and with 12- to 25-s delay calculated with a preliminary test bolus. Three-dimensional shaded surface display (3D SSD) and maximum intensity projection (MIP) reconstructions were obtained from axial images. Then, within 48 h, all patients were submitted to digital subtraction angiography (DSA), with separate assessment of CTA and DSA findings. Twenty-two aneurysms shown by CTA were confirmed at DSA and surgery (true positives), whereas the vascular lesion was not confirmed at DSA in 2 cases (false positives). The presence of intracranial aneurysms was excluded at both CTA and subsequent DSA in 7 cases (true negatives) and there were no false negatives; sensitivity was 100 %, specificity 77.8 %, and diagnostic accuracy 93.5 %. Computed tomography angiography aneurysm location was confirmed at surgery in all cases, with very high accuracy in assessing the presence of an aneurysm neck (100 %). Computed tomography angiography accurately depicted the aneurysm shape in 20 of 22 cases, but failed to depict its multilobed nature in 2 cases. The mean aneurysm diameter calculated at CTA was 0.99 ± 0.12 cm vs 1.09 ± 0.11 cm at surgery (p < 0.01). The present results suggest that the high sensitivity of CTA, if confirmed by further studies, might help in avoiding having to resort to arteriography after negative CTA in SAH patients. Received 15 July 1997; Revision received 30 September 1997; Accepted 5 November 1997     

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

AIM: The aim of this study was to assess the usefulness of 16-row multislice CT angiography (CTA) in evaluating intracranial aneurysms, by comparison with conventional digital subtraction angiography (DSA) and intraoperative findings. METHODS: A consecutive series of 57 patients, scheduled for DSA for suspected intracranial aneurysm, was prospectively recruited to have CTA. This was performed with a 16-detector row machine, detector interval 0.75 mm, 0.5 rotation/s, table speed 10mm/rotation and reconstruction interval 0.40 mm. CTA studies were independently and randomly assessed by two neuroradiologists and a vascular neurosurgeon blinded to the DSA and surgical findings. Review of CTA was performed on workstations with an interactive 3D volume-rendered algorithm. RESULTS: DSA or intraoperative findings or both confirmed 53 aneurysms in 44 patients. For both independent readers, sensitivity and specificity per aneurysm of DSA were 96.2% and 100%, respectively. Sensitivity and specificity of CTA were also 96.2% and 100%, respectively. Mean diameter of aneurysms was 6.3mm (range 1.9 to 28.1 mm, SD 5.2 mm). For aneurysms of less than 3 mm, CTA had a sensitivity of 91.7% for each reader. Although the neurosurgeon would have been happy to proceed to surgery on the basis of CTA alone in all cases, he judged that DSA might have provided helpful additional anatomical information in 5 patients. CONCLUSION: The diagnostic accuracy of 16-slice CTA is promising and appears equivalent to that of DSA for detection and evaluation of intracranial aneurysms. A strategy of using CTA as the primary imaging method, with DSA reserved for cases of uncertainty, appears to be practical and safe.     

Comparison of 16-row multislice CT angiography with conventional angiography for detection and evaluation of intracranial aneurysms

Purpose

The aim of this study is to compare the diagnostic performance of 16-row computed tomographic angiography (MDCTA) with digital subtraction angiography (DSA) for the detection and characterization of intracranial aneurysms in patients with nontraumatic subarachnoid hemorrhages (SAH).

Materials and methods

One-hundred and twelve consecutive patients with suspected intracranial aneurysm underwent both 16-row MDCTA and DSA. The MDCT angiograms were interpreted in a blinded fashion by using combination with VRI, MIP and MPR techniques. Sensitivity specificity and accuracy were calculated for the CTA and DSA. The results were compared with each other. The DSA reader's interpretation was accepted as the reference standard.

Results

A total of 164 aneurysms were detected at DSA in 112 patients, no aneurysms were detected by DSA and MDCTA in 16 patients. Eight aneurysms were missed by MDCTA. The overall sensitivity, specificity, and accuracy of MDCTA on a per-aneurysm basis were 95.1%, 94.1%, and 95%, respectively. According to the size of the aneurysm less than 3 mm; sensitivity, specificity and diagnostic accuracy of MDCTA were 86.1%, 94.1%, 88.6%, respectively.

Conclusion

This study suggests that MDCTA is equally as sensitive as DSA in the detection of intracranial aneurysms of greater than 3 mm, and it also reveals 100% detection rate for ruptured aneurysms.     

Value of CT and MR angiography for diagnostics of intracranial aneurysms

Digital subtraction angiography (DSA) is still considered the gold standard in neurovascular imaging. However, due to permanent progress in the field of cross-sectional imaging modalities many questions can be answered with these less invasive methods. The following article gives an overview of the principles of computed tomography angiography (CTA) and magnetic resonance angiography (MRA) and demonstrates the growing importance in the diagnosis and follow-up of intracranial aneurysms.     

CT血管成像和MR血管成像对颅内动脉瘤诊断价值的比较

目的 采用Meta分析法比较CT血管成像（computer tomography angiography，CTA）和MR血管成像（magnetic resonance angiography，MRA）对颅内动脉瘤的诊断价值。方法 检索Cochrane图书馆、Medline、Ovid数据库和中国期刊网中有关的中英文文献，按照Cochran协作网推荐的诊断试验纳入标准选取A级文献，并提取纳入研究的诊断信息。统计分析采用Meta-Test version 0．9软件，检验异质性，再根据异质性结果选择相应的效应模犁。对所纳入的研究予以加权定量合并，计算汇总敏感度和特异度及其95％可信区间，绘制汇总受试者工作特征曲线（SROC）。结果 按照纳入标准共获取文献11篇，其中有关CTA诊断颅内动脉瘤4篇（单层螺旋CT），MRA为5篇[三维时间飞跃法（3D TOF）]，二者共同研究者2篇；前瞻性研究7篇，回顾性4篇；各组研究均存在异质性，按照随机效应模型对纳入文献行汇总分析。结果显示，对于每个颅内动脉瘤CTA诊断的敏感度、特异度及95％可信区间分别为0．84（0．78～0．88）和0．77（0．68～0．84），MRA分别为0．68（0．63～0．72）和0．76（0．70～0．82）；SROC曲线下面积分别为95．40％和79．71％。结论 对于每个颅内动脉瘤，CTA诊断的准确性明显高于3D TOF法MRA。     

Bone-subtraction CT angiography: evaluation of two different fully automated image-registration procedures for interscan motion compensation

BACKGROUND AND PURPOSE: Bone-subtraction techniques have been shown to enhance CT angiography (CTA) interpretation, but motion can lead to incomplete bone removal. The aim of this study was to evaluate 2 novel registration techniques to compensate for patient motion. MATERIALS AND METHODS: Fifty-four patients underwent bone-subtraction CTA (BSCTA) for the evaluation of the neck vessels with 64-section CT. We tested 3 different registration procedures: pure rigid registration (BSCTA), slab-based registration (SB-BSCTA), and a partially rigid registration (PR-BSCTA) approach. Subtraction quality for the assessment of different vascular segments was evaluated by 2 examiners in a blinded fashion. The Cohen kappa test was applied for interobserver variability, and the Wilcoxon signed rank test, for differences between the procedures. Motion between the corresponding datasets was measured and plotted against image-quality scores. RESULTS: Algorithms with motion compensation revealed higher image-quality scores (SB-BSCTA, mean 4.31; PR-BSCTA, mean 4.43) than pure rigid registration (BSCTA, mean 3.88). PR-BSCTA was rated superior to SB-BSCTA for the evaluation of the cervical internal and external carotid arteries (P<.001), whereas there was no significant difference for the other vessels (P=.157-.655). Both algorithms were clearly superior to pure rigid registration for all vessels except the basilar and ophthalmic artery. Interobserver agreement was high (kappa=0.46-0.98). CONCLUSION: Bone-subtraction algorithms with motion compensation provided higher image-quality scores than pure rigid registration methods, especially in cases with complex motion. PR-BSCTA was rated superior to SB-BSCTA in the visualization of the internal and external carotid arteries.     

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.     

64层螺旋CTA在颅内动脉瘤术前及术后的应用价值

目的：探讨64层螺旋CT血管造影（CTA）对颅内动脉瘤术前诊断及术后评价的应用价值。方法：回顾性分析临床怀疑为颅内动脉瘤患者25例,行64层螺旋CTA检查,其中21例诊断为动脉瘤,并经手术证实,术后亦行CTA复查,通过比较两次CTA结果评价动脉瘤夹闭情况。结果：在25例患者中共发现21例25个动脉瘤,CTA可清楚显示的动脉瘤位置、大小形态及与周围结构的关系,与手术所见一致（符合率100％）;术后CTA能够清楚显示动脉瘤体消失,载瘤动脉与动脉瘤夹之间关系及动脉瘤夹的数量和位置。结论：64层CTA在诊断颅内动脉瘤及动脉瘤术后随访中具有重要临床价值。     

数字减影CT血管造影对颅内动脉瘤的诊断价值

目的 :探讨数字减影CT血管造影(digital subtraction CT angiography,DSCTA)对颅内动脉瘤的诊断价值。方法 :回顾性分析30例颅内动脉瘤合并自发性蛛网膜下腔出血患者的临床及影像学资料,并行MIP、VR观察动脉瘤。结果:30例共37个动脉瘤,前交通动脉6个,大脑前动脉2个,大脑中动脉9个,后交通动脉16个,基底动脉2个,颈内动脉2个。23例单发,7例多部位动脉瘤。DSCTA共发现35个动脉瘤,漏诊2个。动脉瘤大小3 mm×2.9 mm~12 mm×10 mm。18例行弹簧钢圈栓塞。7例行开颅夹闭术。DSCTA检查的敏感度为94.59%,特异度为100%,准确率为94.59%。结论:DSCTA是一种快速准确诊断颅内动脉瘤的非侵袭性检查方法,对颅内动脉瘤的检出具有极高的敏感性和特异性,为临床治疗方案的选择提供了可靠依据,有极高的临床价值。     

Sixty-four-row multisection CT angiography for detection and evaluation of ruptured intracranial aneurysms: interobserver and intertechnique reproducibility

BACKGROUND AND PURPOSE: The purpose of this work was to assess intertechnique and interobserver reproducibility of 64-row multisection CT angiography (CTA) used to detect and evaluate intracranial aneurysms. MATERIALS AND METHODS: From October 2005 to November 2006, 54 consecutive patients with nontraumatic subarachnoid hemorrhage (SAH) underwent both CTA and digital substraction angiography (DSA). Four radiologists independently reviewed CT images, and 2 other radiologists reviewed DSA images. Aneurysm diameter (D), neck width (N), and the presence of a branch arising from the sac were assessed. RESULTS: DSA revealed 67 aneurysms in 48 patients and no aneurysm in 6 patients. Mean sensitivity and specificity of CTA for the detection of intracranial aneurysms were, respectively, 94% and 90.2%. For aneurysms less than 3 mm, CTA had a mean sensitivity of 70.4%. Intertechnique and interobserver agreements were good for the detection of aneurysms (mean kappa = 0.673 and 0.732, respectively) and for the measurement of their necks (mean kappa = 0.753 and 0.779, respectively). Intertechnique and interobserver agreements were excellent for the measurement of aneurysm diameters (mean kappa = 0.847 and 0.876, respectively). In addition, CTA was accurate in determining the N/D ratio of aneurysms and adjacent arterial branches. However, the N/D ratio was overestimated by all of the readers at CTA. CONCLUSION: Sixty-four-row multisection CTA is an imaging method with a good interobserver reproducibility and a high sensitivity and specificity for the detection and the morphologic evaluation of ruptured intracranial aneurysms. It may be used as an alternative to DSA as a first-intention imaging technique in patients with SAH.     

螺旋CT血管造影诊断颅内动脉瘤的研究

目的：评价螺旋CT脑血管造影的临床应用价值。方法：对24例脑血管病变行螺旋CT血管造影检查，三维重建采用表面遮盖法显示(surface shaded display，SSD)，最大密度投影(maximum intensity projection，MIP)。结果：螺旋CT血管造影能较好显示正常脑血管的形态和病变，在24例进行CTA造影的患者中，颅内动脉瘤17例。有7例SCTA未见异常。在11例进行DSA造影的患者中，有10例与SCTA结果相符，仅1例DSA诊断小脑上动脉动脉瘤，而SCTA显示阴性。结论：SCTA是诊断颅内动脉瘤的一种有效无创性检查方法，具有重要的诊断价值。     

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     

Three-dimensional rotational angiography for craniotomy planning and postintervention evaluation of intracranial aneurysms

Purpose

The authors evaluated the usefulness of three-dimensional rotational angiography (3DRA) in surgical planning and postoperative evaluation of cerebral aneurysms.

Materials and methods

A total of 111 consecutive aneurysms in 100 patients (32 emergency referrals due to haemorrhage) were evaluated with 3DRA over a period of 3 years. The rotational study was always performed with a single injection of 20 cc of contrast agent in the afferent vessel after diagnostic cerebral angiography in the two orthogonal projections. Three-dimensional reconstructions were obtained for the pre- and postoperative assessment.

Results

Three-dimensional RA provides a virtual view of the surgical field with the same orientation required for the surgical approach and, compared with surgical findings, reliably defined location, orientation, morphology and relationship with parent vessels of the aneurysm in all cases. Postoperatively, it allowed better assessment of any residual lesion and of the relationship between surgical clips and parent vessels, compared with standard 2D angiography.

Conclusions

3DRA is a reliable method for preliminary assessment of cerebral aneurysms undergoing surgery. It provides multiple projections with a preview of the surgical field and study of lesion characteristics, which can help achieve faster and safer surgery. Compared with 2D angiography, the 3D model, with its multiple views, allows better assessment of postoperative outcomes. The method also significantly reduces the number of angiographic projections and therefore radiation and contrast-medium dose to the patient.     

Subtraction CT angiography with controlled-orbit helical scanning for detection of intracranial aneurysms.

PURPOSEOur goal was to evaluate the utility of subtraction three-dimensional CT angiography for the detection of intracranial aneurysms.METHODSThirty-six patients with intracranial aneurysms were examined using newly devised controlled-orbit helical scanning and conventional angiography. Three-dimensional CT angiograms and subtraction 3-D CT angiograms were compared with conventional angiograms for their characterization of intracranial aneurysms.RESULTSFifty aneurysms were depicted on conventional angiograms, of which 48 (96%) were seen on the 3-D CT angiograms. Three-dimensional CT angiography was superior or equivalent to conventional angiography for depicting the shape, direction, and location of 33 (66%) of 50 aneurysms; however, it was often less useful than conventional angiography in delineating intracranial aneurysms adjacent to bone. Subtraction 3-D CT angiograms were obtained in 32 patients with a total of 46 aneurysms (in four cases, aneurysms were not depicted owing to excessive motion artifacts), and were superior or equivalent to conventional angiograms in all 46 cases.CONCLUSIONSSubtraction 3-D CT angiography with the use of controlled-orbit helical scanning is effective in the detection of intracranial aneurysms.     

Value of dual-energy CT angiography in patients with treated intracranial aneurysms

Purpose

To evaluate the ability of dual-energy CT angiography (DECTA) in metal artifact reduction in patients with treated intracranial aneurysms by comparing DECTA-based virtual monoenergetic extrapolations (VMEs) and mixed images (MI).

Methods

Thirty-five patients underwent prospectively a dual-source DECTA (Somatom Force, Siemens Medical Solutions, Forchheim, Germany) after aneurysm repair. A total number of 40 aneurysms (23 treated by coil embolization and 17 treated by surgical clipping) were analyzed. Mixed images (equivalent to a conventional single-energy CT angiography) were compared to VMEs at 75, 95, and 115 keV. Artifact severity was assessed quantitatively by measuring the mean attenuation value and standard deviation within regions of interest placed in the most hypodense coil or clip artifact area. Artifact severity score and contrast vessel score were also assessed qualitatively by two independent blinded readers.

Results

In those aneurysms treated by surgical clipping, quantitative and qualitative analyses showed significant reduction of artifacts on VMEs compared to MI with the best compromise being obtained at 95 keV in order to keep an optimal vessel contrast in the adjacent vessel. In those aneurysms treated by coil embolization, there was no significant reduction of artifacts both on quantitative and qualitative analyses.

Conclusion

Dual-source DECTA was helpful in order to reduce clip artifacts on VMEs with the optimal adjacent vessel visualization obtained at 95 keV, whereas this technique was not helpful in aneurysms treated by coiling.