| Background:According to previous studies, the incidence of subarachnoid hemorrhage is about 90/1 million, about 85% of which is because of intracranial aneurysm rupture. Although the incidence of aneurysm ruptured subarachnoid hemorrhage is not high, it causes high mortality and morbidity. Hence, even about only 5% of all strokes, the socio-economic loss of SAH is comparable to that of the more common ischemic and hemorrhagic strokes.The prevalence of intracranial aneurysms is about 1%-6% in adults. But in crowd with a family history of aneurysms, the prevalence rate can be as high as 9.5%. Intracranial aneurysms appear mostly in bifurcation of vascular, especially the bifurcation of the brain base blood vessels, such as Willis ring or nearby bifurcation. The majority of intracranial aneurysms (80-85%) are located in the anterior circulation, most commonly at the junction of the internal carotid artery and the posterior communicating artery, the anterior communicating artery complex, or the trifurcation of the middle cerebral artery. Aneurysms of the posterior circulation are most frequently located at the bifurcation of the basilar artery or the junction of a vertebral artery and the ipsilateral posterior inferior cerebellar artery. Multiple intracranial aneurysms, usually two or three in number, are found in 20-30% of patients.Due to lack of specific symptoms and signs, the diagnosis of intracranial aneurysms is usually retrospective diagnosis. For aneurysmal subarachnoid hemorrhage, its early diagnosis can be achieved by CT examination, especially in the early onset of CT examination revealed a typical distributed in subarachnoid/basement pool of blood. Digital subtraction angiography (DSA) technology is regarded as the "gold standard" of the diagnosis of intracranial aneurysms. It could present high resolution by using 1024 x 1024 pixel imaging, and achieve good sensitivity and specificity. However, as invasive operation, the DSA requires high experience and technique. And it takes more time and cost than CT angiography. All these factors limit DSA applying in grass root hospitals. Compared with DSA, CT angiography is rapid, noninvasive and economical. Because good presentation of the aneurysm neck, parent artery and the skull, CT angiography is of great help to work out plans of aneurysms clip. For larger aneurysms, CT angiography especially multi-slice CT angiography can achieve high diagnosis accuracy similar to DSA. Hence, CT angiography (CTA) is being increasingly applied to the diagnosis of intracranial aneurysms.Aims:To calculate the sensitivity and specificity of computed tomographic angiography (CTA) in the diagnosis of intracranial aneurysms in patients suspected with acute subarachnoid hemorrhage (SAH) at presentation.Methods:A systematic search for relevant studies was performed of the PubMed/MEDLINE EBSCO, and Scopus databases. The methodologic quality of each study was assessed by using the Quality Assessment of Diagnostic Accuracy Studies tool. The inclusion criteria were met by 58 studies. Heterogeneity was tested, and the presence of publication bias was visually assessed (by using a funnel plot). A meta-analysis of the reported sensitivity and specificity of each study with 95% confidence intervals (CIs) was performed on a per-patient level and a per-aneurysm level.A retrospective review compared head CTA performed after hours for SAH to the results of DSA. The sensitivity and specificity of CTA were classified on a per-patient and per-aneurysm basis. The accuracy of CTA was also determined according to aneurysm location and number.Results:The selected studies showed moderate heterogeneity. And moderate-heterogeneity studies that investigated only sensitivity or specificity were excluded from the pooled analyses by using a bivariate random effects model. The studies had good methodologic quality. Pooled sensitivity was 0.991 (0.982-1.00,95%CI), and pooled specificity was 0.931 (0.903-0.951,95%CI). Potential sources of variability among the studies were variations in the methodologic features (quality score), CT examination procedure (number of rows on the multi-detector CT scanner), the standard of reference used, and the prevalence of ruptured intracranial aneurysms. There was little evidence for publication bias, which may have led to overestimation of the diagnostic accuracy of CT angiography. The diagnostic accuracy of CT angiography with 64- or 320-row multi-slice CT was significantly higher than that of single- or 4-row multi-slice CT, especially in detecting small aneurysms of ≤3mm in diameter.When using intra-arterial digital subtraction angiography,331 aneurysms (true positives and false negatives) were detected in 300 of the 429 patients..The mean diameter of aneurysms was 4.14 mm. A total of 320 aneurysms (true positives) were confirmed by using digital subtraction angiography.94 aneurysms were missed when using 16-row multi-slice CT angiography.11 aneurysms were not confirmed by digital subtraction angiography and were considered to be false positive evaluations. The sensitivity for detecting aneurysms<3 mm,3 to 5 mm,5 to 10mm, and>10mm on a per-aneurysm basis was 0.548 (0.462-0.634,95%CI),0.852 (0.789-0.902,95%CI), 0.912 (0.847-0.965,95%CI), and 1.00 (0.990-1.00,95%CI), respectively. The sensitivity, specificity, and accuracy of multi-slice CT angiography for detecting aneurysms on a per-patient basis were 0.851 (0.809-0.889,95%CI),0.951 (0.909-0.977, 95%CI), respectively. It is easier to detect aneurysms located in anterior communicating artery or middle cerebral artery than any other location, and the sensitivity was 0.837(0.760-0.897,95%CI), and 0.805(0.651-0.902,95%CI), respectively. For ruptured aneurysms, sensitivity was 0.874 (0.823-0.916,95%CI), higher than unruptured aneurysms. The sensitivity of patients with 4 or 5 Hunt-Hess scores was 0.933 (0.685-0.998,95%CI), and it was 0.857 (0.801-0.902,95%CI) of patients with lower Hunt-Hess scores.Conclusions:From meta-analysis it is found that for aneurysm more than 3mm, all the CT angiography showed a high diagnostic accuracy, and with the number of row CT increasing, the accuracy of CT angiography is higher. For aneurysm less than 3mm,64-row and 320-row CT angiography showed good diagnostic accuracy, but lower row CT angiography couldn’t find smaller aneurysms.According to data of CT angiography from our center, the CT angiography showed preferable sensitivity and specificity; the sensitivity and specificity respectively is 85.1% and 95.1% per patient, and 77.3% and 94.1% per aneurysm. But for aneurysms less than 3 mm in diameter or located in the posterior fossa or close to the base, sensitivity and specificity of CT angiography in the diagnosis of intracranial aneurysms is decreased., Therefore, CT angiography can hardly replace DSA for the diagnosis of intracranial aneurysms in clinical application... |
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