The Value Of 64-detector Spiral Ct Angiography In The Diagnosis Of Intracranial Aneurysm

Background and objective: Intracranial aneurysm(AN) is the primarycause of spontaneous subarachnoid hemorrhage(SAH), accounting for 70%～85%.The mortality and mutilation rates are both quite high. So early diagnosis and timely treatment are clinically significant for the prognosis.Now, the common intracranial aneurysm diagnosis modalities are Magnetic Resonance Angiography(MRA), Digital Subtraction Angiography(DSA) and Computed Tomography Angiography (CTA). With the characters of non-invasive, fast operation, low cost, less complication and indications, wide range of using, high sensitivity and the three-dimensional image, CTA are used to clinical application more and more. Also with the rapid development of multi-detector spiral CT, the diagnostic accuracy of intracranial aneurysms has been greatly improved. The literature reported that the diagnosis coincidence rate of intracranial aneurysm by multi-detector spiral CT angiography could be to 100%.The basic principle of CTA is to combine the acquisition technique of volume CT and computer three-dimensional reconstruction image processing technology. Through many studies, scholars present that CTA can be used as the preferred diagnostic method for the diagnosis of intracranial aneurysm. With the advantage of intracranial aneurysm three-dimensional display, arbitrary angle repeated observation, appearance and measurement of internal structure, vascular walls, relationship with adjacent structures and aneurysm carrying artery, the sensitivity and specificity of CTA is close to DSA. GE 64-detector lightspeed VCT, representing the new generation of CT, scan faster, 0.35 second/cycle, spatial resolution 0.4mm, thinner slice 0.625mm, contain more information, with post-processing images more accurate and clear, for example: volume rendering, maximum intensity projection, multi-planar reconstruction, curved planar reconstruction, advanced vessel analysis, et al. The delay time of setting precisely is the success to 64-detector on head-neck CTA and the key to diagnosis intracranial aneurysm. Nowadays, there are two subtraction tracing scan style on use as low-dose bolus test tracing scan style and timing bolus tracking scan style of Smart Prep software. To investigate the subtraction technique and the advantages of 64 detector spiral CT in the diagnosis of intracranial aneurysm, we design this subject.Materials and method: CTA imagines of 70 cases with intracranialaneurysm confirmed by surgery or DSA from May 2008 to February 2009 in the hospital were collected, with male 32 cases, female 38 cases, between 10～77 years, 54.7 years old on average. Within the patients, DSA inspected 20 cases, interventional coil embolized 22 intracranial aneurysms at the same time, 50 cases with surgical clipped or strengthening with parcels to 55 intracranial aneurysms. All imagines were processed on GE advantage workstation 4.3(ADW 4.3).①Assess the different trigger scan style according to whether the ICA and VA are clear, the skull base and cervical bone structures remain or the main branches of blood vessels appear.②Evaluate the image quantities according to the intracranial aneurysm appearance, 3D relations, smooth degree and vessels.③Observe the intracranial aneurysm on CTA imagines, record the therapy scheme, the location and complications of each intracranial aneurysm, compute the proportion of various types by intracranial aneurysm thrombus.④Measure the maximum diameter of each intracranial aneurysm on CTA 2D-VR and MPR Reformat image and DSA by three radiologist, compare the measurement between the CTA, DSA or the operation, Group intracranial aneurysms by the maximum diameter of intracranial aneurysm. All the data treated by SPSS13.0,with P<0.05 for the test standard.Results:①50 cases were used by low-dose bolus test tracing scan style, and 20 cases by timing bolus tracking scan style of Smart Prep software. The reconstruction image quantity is different between low-dose bolus test tracing scan style and timing bolus tracking trigger scan style (Z=2.626, P=0.009).②The results of all the reconstruction images compared: the aneurysms shape side VR and MPR, MIP and MPR are all different (x~2=7.277, 5.463,both P <0.05), VR and MIP is not different (x~2 =4.899,P=0.062), the aneurysms three-dimensional side VR and MPR, MIP and MPR are different(x~2=7.218, 6.870, both P <0.05), VR and MIP is not different(x~2=2.828,P=0.50), the aneurysms evenness side VR and MIP, VR and MPR, MIP and MPR are all different(x~2=4.669, 6.164, 2.524, all P<0.05), the overall side VR andMPR, MIP and MPR are different(x~2=4.716, 5.778, both P<0.05), VR and MIP is not different(x~2 = 1.298,P=0.194).③79 intracranial aneurysms were found in 70 patients, single 62 (88.6%) , double 7 (10.0%) , trigger 1 (1.4%) .77 intracranial aneurysms with therapy, the coincidence rate of CTA diagnosing is 100%, 2 were misjudged.④Different location of the intracranial aneurysms: A com artery 15(19.5%), ICA-C7 segment 12(15.6%), ICA-C4 segment 10(13.0%), MCB 8(10.4%), P com artery 8(10.4%), ICA-C5 segment 5(5.2%), MCA-M1 segment 4(5.2%), ACA-A2 segment 4(5.2%), BA 4(5.2%), ACA-A1 segment 3 (3.9%), PCA2(2.6%), ICA-C6 segment 1 (1.3%), VA1 (1.3%) . Styles by the intracranial aneurysm size: giant 2 (2.6%), large 4 (5.2%), middle 29 (37.7%), small 42 (54.5%) .⑤There are no difference between the maximum diameter of intracranial aneurysm measured by CTA 2D-VR images and MPR Reformat images (F=0.066, P=0.945), no difference between 2D-VR and DSA measured (F=0.200, P=0.853), no difference between 2D-VR and the operation measured (t=0.363, P=0.850).Conclusion:1. Automatic bolus tracking of the Smart Rrep software is the better subtraction trigger scan style within 64-detector spiral CT in cerebral and carotid CTA.2. VR images are the best to assess the intracranial aneurysm location, shape, three dimensional relation and the whole vessels, MIP images are better to assess the intracranial aneurysm shape, the whole vessels, the calcification extent and scope of vessels wall, worse than VR images on intracranial aneurysm evenness and the whole vessels. MPR images display the intracranial aneurysm, are worse to the intracranial aneurysm three-dimensional and whole vessels.3. 64-detector CTA could be used to observe the thrombosis within intracranial aneurysm and diagnosis the complications.4. Both the 64-detector CTA 2D-VR images and MPR reformat images could be used to measure the maximum diameter of intracranial aneurysm, CTA 2D-VR is accurate and convenient to measure.