Assessment of Pre- and Post-Operative Cerebral Perfusion in Anterior Circulation Intracranial Aneurysm Clipping Patients at Hospital Sungai Buloh Using CT Perfusion Scan and Correlations to Fisher, Navarro and WFNS Scores

Background: Intracranial aneurysms may rupture and are typically associated with high morbidity and mortality, commonly due to vasospasm after rupture. Once the aneurysm ruptures, the patient’s cerebral blood flow may be disturbed during the acute phase, affecting cerebral circulation and thus cerebral perfusion prior to the onset of vasospasm. Fisher and Navarro scores are used to predict vasospasm, while World Federation of Neurosurgical Societies (WFNS) scores are used to predict patient outcomes. Several score modifications are available to obtain higher sensitivity and specificity for the prediction of vasospasm development, but these scores are still unsuccessful. Alternatively, cerebral CT perfusion scan (CTP) is a non-invasive method for measuring cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) in regions of interests (ROI) to obtain the cerebral perfusion status as well as detecting vasospasm. Methods: A total of 30 patients’ data with clipped anterior circulation intracranial aneurysms admitted to the hospital between 1 January 2013 and 30 June 2014, were collected from the hospital’s electronic database. The data collected included patients’ admissions demographic profiles, Fisher, Navarro and WFNS scores; and their immediate pre- and postoperative CTP parameters. Results: This study found a significant increase in post-operative MTT (pre- and postoperative MTT) were 9.75 (SD = 1.31) and 10.44 (SD = 1.56) respectively, (P < 0.001)) as well as a significant reduction in post-operative CBF (pre- and post-operative mean CBF were 195.29 (SD = 24.92) and 179.49 (SD = 31.17) respectively (P < 0.001)). There were no significant differences in CBV. There were no significant correlations between the pre- and post-operative CTP parameters and Fisher, Navarro or WFNS scores. Conclusion: Despite the interest in using Fisher, Navarro and WFNS scores to predict vasospasm and patient outcomes for ruptured intracranial aneurysms, this study found no significant correlations between these scores in either pre- or post-operative CTP parameters. These results explain the disagreement in the field regarding the multiple proposed grading systems for vasospasm prediction. CTP measures more than just anatomical structures; therefore, it is more sensitive towards minor changes in cerebral perfusion that would not be detected by WFNS, Fisher or Navarro scores.

Transarterial Embolization with Berenstein Liquid Coils and N-butyl Cyanoacrylate in a Vein of Galen Aneurysmal Malformation: a Case Report

A 12-week-old baby with a vein of Galen aneurysmal malformation (VGAM) was successfully treated with performing transarterial microcatheter-directed embolization with Berenstein Liquid Coils and n-butyl cyanoacrylate in the feeding arteries. Post-procedure angiography showed a marked decrease of the blood flow into the dilated vein of Galen. Three months later, follow-up angiography showed that the vein of Galen aneurysmal malformation had totally disappeared, and the baby recovered very well without any sequelae. We report here on this interesting case along with a review of the relevant literature, and we aim to enhance physicians' awareness of the treatment for VGAMs.

N-butyl Cyanoacrylate Embolization of Intracranial Mycotic Aneurysm: A Case Report / 신경중재치료의학

The intracranial mycotic aneurysms are a rare complication in patients with infective endocarditis, and the management of the aneurysm is controversial. We presented a case of a 50-year-old woman who had infective endocarditis, complicated by an intracranial mycotic aneurysm of distal branch of the right anterior cerebral artery. Endovascular treatment using cyanoacrylate led to a successful result.

Glue Embolization of Aneurysm after Stenting in Canine Carotid Arteries - Technical Feasibility

PURPOSE: Coiling or infusion of embolic materials into a wide necked aneurysm can be performed with stenting. The purpose of our study is to assess the technical feasibility of aneurysm treatment with glue embolization after stenting. MATERIALS AND METHODS: We used four Wallstents for surgically repairing eight canine carotid aneurysms. After confirmation of the aneurysms on the angiogram, we introduced a 6-7 F guiding catheter in order to deploy the stents. After stenting, we passed a microcatheter into the aneurysm lumen through the stent mesh. 28% glue was slowly injected until the glue cast completely filled the lumen. We evaluated the passage of a microcatheter through the stent meshwork, formation of the glue cast and the stents' ability to protection for any leakage of glue. The follow-up angiogram was obtained for two dogs, one to three times until 8 weeks, and then we sacrificed the dogs and performed pathologic examinations. RESULTS: Stenting was successful in all cases except one in which the vessel was occluded because the stent was not completely expanded within the lumen. The microcatheter could not pass through the stent mesh in one aneurysm. The two week follow-up angiogram showed complete occlusion of the aneurysm and a patent carotid lumen in a case after successful stenting and glue embolization without distal migration of glue. Tungsten in the glue was noted to migrate out of aneurysm into the soft tissue of the neck. Histopathologic examination showed successful obliteration and stable organization of the aneurysmal lumen with ingrowth of fibroblasts and a foreign body reaction. In contrast, the aneurysms without the glue embolization being performed showed partially thrombosed aneurysmal lumens that became smaller and indistinct on the 8 week follow-up angiograms. Histopathologic examination showed a disorganized thrombus with numerous recanalizations. CONCLUSION: Glue embolization after stenting could be performed for aneurysm without distal migration of the glue or gluing of the catheter. This concept appears to be useful for applications to the further research and the treatment of aneurysm.

Migration of a Slipped Aneurysmal Clip from the Intracranium into the Spinal Canal: Case Report

Very rarely, clips used for the ligation of intracranial aneurysms become detached and subsequently migrate into the spinal canal, causing lumbar pain or radiculopathy by compressing nerve roots or inducing inflammatory processes in their newly established location. However, it is easy to overlook the migration of the clip, because there may be either no noticeable symptoms, or a herniated disk may be mistakenly diagnosed as being the source of the present symptoms. Herein, the authors report a case in which an aneurysmal clip migrated into the spinal cord.

Turnover in Intracranial Aneurysm Phantoms: Its Relation to Neck Size

PURPOSE: To evaluate the physiologic background of aneurysms poorly visualized during 3D-TOF MRA, contrast-enhanced MRA (CEMRA) and DSA due to hemodynamic isolation. MATERIALS AND METHODS: Using handmade elastic silicon phantoms to represent terminal basilar tip aneurysms, 3D-TOF MRA, CEMRA and DSA were used to determine blood turnover. Aneurysmal neck size was 2 mm and 10 mm, and the use of a pulsatile pump also helped recreate human physiologic parameters. We compared the results with those of computational fluid dynamics. RESULTS: DSA images of the narrow-necked aneurysm showed that a small volume of contrast medium washed into it during the systolic phase. As the width of its neck increased, the turnover volume of fragments of contrast bolus also increased. At CEMRA, the broad-necked aneurysm was visualized as the main bolus of Gd-DT PA passed through it, and at delayed CEMRA, the narrow-necked aneurysm was visualized faintly after the passage of bolus Gd-DT PA. The results correlated closely with those of 3DTOF MRA and computational fluid dynamics. CONCLUSION: The visualization of intracranial aneurysms at 3D-TOF MRA, CEMRA and DSA was greatly dependent upon blood turnover, which varied according to aneurismal neck size. A narrow-necked aneurysm might be missed at 3D-TOF MRA, CEMRA and DSA due to hemodynamic isolation.

Unruptured Aneurysms with Cranial Nerve Symptoms: Efficacy of Endosaccular Guglielmi Detachable Coil Treatment

OBJECTIVE: To evaluate the efficacy of endosaccular Guglielmi detachable coil (GDC) treatment of unruptured aneurysms causing cranial nerve (CN) symptoms. MATERIALS AND METHODS: Among a database of 218 patients whose aneurysms were treated using GDC, seven patients met the criteria for unruptured aneurysms presenting with symptoms and signs of CN palsy. Changes in CN symptoms before and after GDC treatment were reviewed. RESULTS: Aneurysms were located in the internal carotid-posterior communicating artery (n=3), the basilar bifurcation (n=1) and the cavernous internal carotid artery (n=3). CN symptoms included ptosis (n=6), mydriasis (n=2), and extraocular muscle (EOM) disorder (CN III: n=4; CN VI: n=3). Overall, improvement or resolution of CN symptoms after treatment was noted in five patients. CN symptoms in cases involving small (< or =10 mm) and intradural aneurysms tended to respond better to GDC treatment. Ptosis was the initial symptom to show improvement, while EOM dysfunction responded least favourably. CONCLUSION: GDC coil packing appears to be an appropriate treatment method for the relief of CN symptoms associated with intracranial aneurysms.

Infraoptic Course of the Anterior Cerebral Artery: Case Report

An infraoptic anterior cerebral artery (ACA) arising at a low bifurcation of the internal carotid artery is a rare anomaly, of which about 33 cases have been reported to date, often in association with cerebral aneurysms. We describe a case involving an infraoptic ACA in which a ruptured middle cerebral artery aneurysm was also present. Angiography revealed the presence of an abnormal solitary ACA, arising from the intracranial proximal internal carotid artery near the origin of the ophthalmic artery, and a contralateral middle cerebral artery aneurysm. Magnetic resonance imaging showed that the ACA passed below the ipsilateral optic nerve, anterior to the optic chiasm, to join the normally positioned anterior communicating artery above the optic chiasm.

Stent Assisted Coil Embolization of a Dissecting Aneurysm of the Vertebral Artery: A Case Involving a Patient with Hypoplasia of the Contralateral Vertebral Artery

A dissecting aneurysm of the vertebral artery may be treated conservatively, surgically, or using an endovascular approach. Proximal clipping, wrapping or trapping are surgical treatment methods, and endovascular treatment with coils and balloons is performed where a dissecting aneurysm is located near the midline or the appropriate surgical manipulation is difficult. As the contralateral vertebral artery of this patient was hypoplastic, the stent-assisted coil embolization technique was employed to preserve the ipsilateral vertebral artery. We describe a clinical case of dissecting aneurysm of the vertebral artery occurring in a patient in whom a hypoplastic contralateral vertebral artery was successfully treated.

Comparison of CT Angiography and Digital Subtraction Angiography in the Evaluation of Intracranial Aneurysmal Neck

PURPOSE: To compare the usefulness of three-dimensional multislice CT angiography(CTA) and digital subtraction angiography (DSA) in the evaluation of intracranial aneurysmal neck. MATERIALS AND METHODS: Nineteen patients with intracranial aneurysm (23 cases) underwent DSA and subsequent CTA. Using a multislice CT scanner and the SSD(shaded surface display) technique, clipping, cutting and the MPR technique, three-dimensional images were obtained. These were (a) external, (b) internal, from the direction of the parent artery, (c) internal, from the direction of the aneurysmal dome, and (d) an aneurysmal cutting image. The CTA findings were retrospectively compared with the DSA images. RESULTS: Twenty aneurysms were small and three were large. In eleven cases aneurysm neck was small, in nine it was wide, and in three it was relatively wide. For aneurysnal neck evaluation, CTA was superior to DSA in six of nine wide-neck aneurysms and all three large-sized wide-neck aneurysms. In small neck aneurysms 8 of 11 cases and in relatively wide neck all 3 cases showed similarly good images by both modalities. Of the 23 cases demonstrated by four different images, 14 cases showed the best image in internal image from parent artery direction and 6 cases showed similarly good image in both aneurysmal cutting image and internal image from parent artery direction. In the evaluation of wide neck aneurysms, 7 of 9 cases showed the best image at internal image from parent artery direction, compared with other three different images. In two cases of aneurysms, calcification was visible in the aneurysmal wall, so it was difficult to evaluate the aneurysmal neck. CONCLUSION: CTA was superior to DSA in the evaluating the intracranial aneurysmal neck. CTA maybe an additional available modality to evaluate the aneurysmal neck which is difficult to detect by the DSA. And the information of intracranial aneurysmal neck through CTA will be of value in surgical and endovascular treatment.

GDC Embolization of Wide-necked Cerebral Aneurysms Using Balloon-Assisted Technique

PURPOSE: The main factor limiting endovascular treatment of intracranial aneurysms is the shape of the a-neurysmal sac, especially the width of the neck. We describe an early experience and technical aspects of treating wide-necked cerebral aneurysm using a Guglielmi detachable coil (GDC) and simultaneous application of a temporary balloon. MATERIALS AND METHODS: Four cases of unruptured wide-necked cerebral aneurysm were treated with GDC, with simultaneous application of a temporary balloon. Patients were aged between 29 and 49 years. On admission, clinical presentation was subarachnoid hemorrhage (SAH) in all cases. Hunt and Hess grade was II in two cases, III in one case, and traumatic SAH in one case. In all patients angiography revealed an asymptomatic a-neurysm after rupture of another aneurysm or traumatic SAH. The aneurysms were occluded with GDC-10, and a Cirrus balloon occlusion system was used simultaneously. All procedures were performed under endo-tracheal general anesthesia and systemic heparinization. RESULTS: All cases were treated successfully, without parent artery compromise. The occlusion rate at the end of the procedure was total in three cases and subtotal in one. In one case a heparin-related hematoma occurred during post-procedural treatment and the patient eventually expired. One patient underwent follow-up angiography after 6 months, and the coil was not changed. CONCLUSION: An aneurysm may not be completely occluded, but with regard to coil compaction and parent artery preservation, the technique is an attractive alternative.

Prediction of Parent Artery of Anterior Communicating Artery Aneurysm on CT Angiography

PURPOSE: To determine whether CT angiography can predict the parent artery of an anterior communicating aneurysm on the basis of characteristics of the aneurysm and precommunicating anterior cerebral artery. MATERIALS AND METHODS: Eighteen patients with anterior communicating aneurysm were studied prospectively using CT angiography and conventional angiography. The parent artery of an aneurysm was predicted by evaluating aneurysm neck location, direction of aneurysm projection, and size of the precommunicating anterior cerebral artery, as seen on CT angiography. A somatom Plus-4 spiral CT scanner was used and shaded-surface display three-dimensional images were constructed. RESULTS: Aneurysm neck was located near the parent artery in 12 cases(66.7%), and aneurysm projection was against the parent artery in 11 cases(61.1 %). The parent artery of the anterior cerebral artery was larger in 15 cases (8 3 .3 %), including ten cases of hypoplasia or agenesis of the contralateral anterior cerebral artery. In 17 of 18 aneurysms(94.4%) the parent artery seen on DSA was correctly predicted by CT angiography. CONCLUSION: Teh parent artery of an anterior communicating aneurysm can be predicted by evaluating a-neurysm neck location, direction of aneurysm projection, and precommunicating anterior cerebral artery, as seen on CT angiography.

Diagnostic Accuracy of Three-dimensional CT Angiography in Intracranial Aneurysms

PURPOSE: To determine the accuracy of three-dimensional CT angiography(CTA) in the diagnosis of intracranialaneurysms. MATERIALS AND METHODS: 3D-CTA was performed in 46 consecutive patients with subarachnoid hemorrhage orsuspected intracranial aneurysm. Images were obtained using a helical CT scanner and the SSD techinque. 3D CTAfindings were reviewed retrospectively and independently in blind fashion by two neuroradiologists. Digitalsubtraction angiography(DSA) was used as the reference standard. RESULTS: DSA revealed, in 36 patients, 40aneurysms ranging from 2mm to 12mm in maximal diameter, and negative findings in 10 patients. For observer 1, theaccuracy of 3D-CTA for all aneurysms and all patients was 85.2% and 82.7%, respectively. For observer 2, therespective figures were 94.6% and 91.9%. The agreement rates between the two observers were 86% for all aneurysmsand 87% for all patients (Kappa value 0.58, 0.59). CONCLUSION: Three-dimensional CTA is a useful imagingtechnique for the diagnosis of intracranial aneurysms, with an accuracy of over 85%

Radiologic Findings of Acute Spontaneous Subdural Hematomas

PURPOSE: To evaluate the characteristic CT and cerebral angiographic findings in patients with acutespontaneous subdural hematomas and correlate these imaging findings with causes of bleeding and clinical outcome. MATERIALS AND METHODS: Twenty-one patients with nontraumatic acute spontaneous subdural hematoma presentingduring the last five years underwent CT scanning and cerebral angiography was performed in twelve. To determinethe cause of bleeding, CT and angiographic findings were retrospectively analysed. Clinical history, laboratoryand operative findings, and final clinical outcome were reviewed. RESULTS: The 21 cases of acute spontaneoussubdural hematomas were caused by cerebral vascular abnormalities(n=10), infantile hemorrhagic disease(n=5), orwere of unknown origin(n=6). All ten cases of cerebral vascular abnormality were confirmed angiographically; sixwere aneurysms, three were arteriovenous malformations, and one was moyamoya disease. On CT, subarachnoidhemorrhage was seen to be associated with aneurysms, intracerebral hemorrhage with arteriovenous malformations,and intraventricular hemorrhage with moyamoya disease. All five patients with hemorrhagic disease were infantsaged 1-17 months ; characteristic diffuse distribution of subdural hematoma in both temporoparietal-occipitalregions is typical. The average overall mortality rate was 52.4%(11/21). In patients with cerebral vascularabnormalities, mortality was as low as 20%(2/10), but in hemorrhagic disease was high (60%). In cases of unknownorigin it was 100%. CONCLUSION: Acute spontaneous subdural hematoma is a rare condition, and the mortality rateis high. In patients with acute spontaneous subdural hematoma, as seen on CT, associated subarachnoid orintracerebral hemorrhage is strongly indicative of intracerebral vascular abnormalities such as aneurysm andarteriovenous malformation, and cerebral angiography is necessary. To ensure proper treatment and thus morkedlyreduce mortality, the causes of bleeding should be prompty determined by means of cerebral angiography.

CT and Angiographic Analysis of Posterior Communicating Artery Aneurysms: What Factors Influence the Amount of Subarachnoid Blood?

PURPOSE: To determine how clinical and angiographic factors relate to the amount of subarachnoid blooddetected by computerized tomography in patients with a ruptured aneurysm. MATERIALS AND METHODS: Between January1996 and December 1997, 22 patients with a posterior communicating artery aneurysm were retrospectively evaluated. RESULTS: Oval(three of four cases), funnel(both cases), and daughter-sac (four of five cases) types of aneurysmalsac were found among the 13 patients with a large amount of subarachnoid blood ; eight of these had a past historyof hypertension or diabetes. Seven of eleven cases of cylindrical-type aneurysmal sac were found among the 9patients with a small amount of sularachnoid blood ; eight of these had no past history of hypertension ordiabetes. The average S/N ratio (ratio of maximum sac length to neck diameter) of patients with a small amount ofblood was higher than that of patients with a large amount of blood(2.72 vs 2.07). CONCLUSION: Although manyfactors influence the amount of subarachnoid blood in an aneurysmal rupture, we found that a large amount of bloodwas frequently present in the oval, funnel and daughter sac types of aneurysm, when S/N ratio was low, and when anunderlying disease such as hypertension or diabetes was present. Conversely, a small amount of blood was presentin the cylindrical type, when S/N ratio was high, and where there was no of underlying disease.

CT Angiography in the Diagnosis of Cerebral Aneurysm: Comparison of MIP and SSD Techniques

PURPOSE: To evaluate the usefulness of CT angiography and to compare SSD(Shaded Surface Display) andMIP(Maximum Intensity Projection) in the diagnosis and preoperative evaluation of the cerebral aneurysms. MATERIALS AND METHODS: Twenty-six aneurysms in 20 patients were diagnosed on conventional angiography and surgerywas performed. For preoperative evaluation, all patients underwent CT angiography, with spiral CT for preoperativeevaluation. Using SSD and MIP techniques, the results were proccessed and compared; three radiologistsretrospectively analysed detectability, size, neck visualization, delineation of shape, direction, therelationship with surrounding vessels-including the feeding artery of the aneurysm-and intraluminal thrombicontaining calcification. RESULTS: Twenty five of 26 aneurysms (96.2%) were detected by CT angiography, while MIPand SSD depicted 25 (96.2%) and 24 (92.3%), respectively. The largest diameter of the aneurysms was 11-15mm infour cases, 6-10mm in ten, and 3-5mm in 12 (mean 7.38mm, SD=3.34). With regard to detectability, MIP led to onefalse negative result, and SSD to two false negative and one false-positive results. Aneurysm neck assessment byMIP was clear in 96.0% of cases (24/25), and by SSD in 83.3% (20/24). For the depiction of directions and feedingvessels of the aneurysms, and intraluminal thrombi containing calcification, MIP was superior to SSD, while fordepicting shape and the relationship with surrounding structures, SSD was superior to MIP. CONCLUSION: For theassessment of cerebral aneurysms, MIP is somewhat superior to SSD. The characteristics of aneurysms and theirrelationship with surrounding structures can, however, be better evaluated by combining the two techniques.

Usefulness of Rotational Angiography in the Assessment of Cerebral Aneurysm and Arteriovenous Malformation

PURPOSE: To evaluate the role of rotational angiography in the diagnosis, characterization, and postoperativeassessment of aneurysm, and in the analysis of arteriovenous malformation(AVM). MATERIALS AND METHODS: Between May1995 and February 1997, 31 patients who had undergone DSA and rotational angiography were retrospectivelyevaluated. Rotational angiographic and lateral DSA images were compared by two radiologists, and in 22 patientswith aneurysmal clipping, location, visibility of the aneurysmal neck, vascular branch anatomy, and projection andshape of the aneurysm were evaluated. The presence or absence of residual aneurysmal neck was evaluated in eightpostoperative patients, and the anatomy of feeder artery and intranidal aneurysm were evaluated in five AVMpatients. RESULT: Twenty-seven aneurysms were found in 22 of 26 patients in whom DSA had indicated thispossibility. Rotational angiography was superior to conventional DSA in the assessment of neck(67%), vascularbranch anatomy(41%), and projection(22%), location(19%), and shape(15%) of the aneurysm. Rotational angiographyhelped confirm the absence of aneurysm at 11 sites, and was also superior to conventional DSA for confirming theabscence of residual neck in four of eight postoperative patients, and to evaluate feeder artery in four of fiveAVM patients. CONCLUSION: Rotational angiography is better than conventional DSA for the evaluation of aneurysmand AVM.

Usefulness of 3 Dimensional CT Angiography in the Diagnosis of Intracranial Aneurysms: Comparative Study with Conventional Angiography

PURPOSE: To assess the diagnostic capability of three-dimensional CT angiography(3D-CTA) in the diagnosis of intracranial aneurysms, compared with conventional angiography. MATERIALS AND METHODS: Twenty-two patients with intracranial aneurysms were studied using 3D-CTA and conventional angiography. Three-dimensional images were obtained with a helical CT scanner using SSD(shaded surface display) technique. 3D-CTA findings were retrospectively compared with conventional angiography with respect to lesion detection and delineation of the aneurysms. RESULTS: Of the 25 aneurysms demonstrated by conventional angiography, 23(92.0%) were detected by 3D-CTA. Aneurysmal necks were clearly visualized in 17 of 25 aneurysms(68.0%) with conventional angiography, and 19 of 23(82.6%) with 3D-CTA. And 3D-CTA is also superior to conventional angiography in aneurysmal delineation. CONCLUSION: 3D-CTA is thought to be a potential imaging modality in the evaluation of intracranial aneurysm, especially in aneurysmal delineation.

Comparison of Magnetic Resonance Angiography and CT Angiography in the Evaluation of Intracranial Aneurysm

PURPOSE: The purpose of this study was to assess the relative diagnostic capability of magnetic resonance angiography(MRA) and CT angiography(CTA) in the evaluation of intracranial aneurysm. MATERIALS AND METHODS: MRA and CTA were performed in 14 intracranial aneurysms (Including four which were ruptured) confirmed in the II patients involved by conventional angiography(CA). The size(in largest dimension) of the aneurysms ranged between 3 mm and 20 mm and the mean was 10.5 mm. For MRA, the 3D TOF method, with magnetization transfer suppression, wasused at 1.5T. For CTA, twenty seconds after beginning the injection of contrast media(100mL with use of a power injector at the rate of 3 mL/sec), CT scanning(30-second exposure and 60-mm length) was performed with a table speed of 2 mm/sec and a section thickness of 2mm. The resulting data were reformatted by MIP. MRA and CTA were compared with regard to the detection of aneurysms and their neck, size, shape, direction, intensity and relationship to adjacent bony structures or vessels. RESULTS: All aneurysms were clearly visualized with CTA. Inone case with a 3-mm aneurysm, however, this was not defined on MRA. Of the 13 aneurysms demonstrated by both MRA and CTA, eight were seen equally well with both modalities. CTA was considered to be superior to MRA in fivecases, either because calcification in the aneurysm wall was seen only on CTA(n = 3) or because the relationship with adjacent bony structures were seen better with CTA(n = 2). With CTA, the intensities of the aneurysm were homogeneous in all cases ; with MRA, however, the intensities of three large aneurysms were different. CONCLUSION: MRA and CTA may be useful in the evaluation of intracranial aneurysm, CTA has specific advantages over MRA inthe evaluation of large aneurysms, calcification of aneurysm wall and relationship with adjacent bony structure.