Detection Of Cerebral Aneurysms Research Articles

Can Computed Tomography Angiography of the Brain Replace Lumbar Puncture in the Evaluation of Acute‐onset Headache After a Negative Noncontrast Cranial Computed Tomography Scan?

The primary goal of evaluation for acute-onset headache is to exclude aneurysmal subarachnoid hemorrhage (SAH). Noncontrast cranial computed tomography (CT), followed by lumbar puncture (LP) if the CT is negative, is the current standard of care. Computed tomography angiography (CTA) of the brain has become more available and more sensitive for the detection of cerebral aneurysms. This study addresses the role of CT/CTA versus CT/LP in the diagnostic workup of acute-onset headache. This article reviews the recent literature for the prevalence of SAH in emergency department (ED) headache patients, the sensitivity of CT for diagnosing acute SAH, and the sensitivity and specificity of CTA for cerebral aneurysms. An equivalence study comparing CT/LP and CT/CTA would require 3,000 + subjects. As an alternative, the authors constructed a mathematical probability model to determine the posttest probability of excluding aneurysmal or arterial venous malformation (AVM) SAH with a CT/CTA strategy. SAH prevalence in ED headache patients was conservatively estimated at 15%. Representative studies reported CT sensitivity for SAH to be 91% (95% confidence interval [CI] = 82% to 97%) and sensitivity of CTA for aneurysm to be 97.9% (95% CI = 88.9% to 99.9%). Based on these data, the posttest probability of excluding aneurysmal SAH after a negative CT/CTA was 99.43% (95% CI = 98.86% to 99.81%). CT followed by CTA can exclude SAH with a greater than 99% posttest probability. In ED patients complaining of acute-onset headache without significant SAH risk factors, CT/CTA may offer a less invasive and more specific diagnostic paradigm. If one chooses to offer LP after CT/CTA, informed consent for LP should put the pretest risk of a missed aneurysmal SAH at less than 1%.

Congenital Absence of the Left Internal Carotid Artery

The absence of the internal carotid artery (ICA) is a rare congenital anomaly, occurring in <0.01% of the population. Aplasia of the ICA may be harmless; however, the significance of ICA aplasia may be associated with conditions of clinical importance, such as in the setting of surgery, thromboembolic disease, and detection of cerebral aneurysms, and therefore should prompt further evaluation to rule out abnormalities. We present a case of left ICA aplasia diagnosed after work-up of neurological events. The incidence of intracranial aneurysm in association with aplasia has been reported as 25-43% compared to 2-4% in the general population. Mechanisms to explain the association between aplasia and intracranial aneurysms include embryological development or hemodynamic derangement. Recognition of this anomaly becomes important in thromboembolic disease as emboli in one cerebral hemisphere may be explained by atherosclerotic disease in the contralateral common carotid artery or vertebrobasilar system. Of significance, planning endarterectomy denotes consideration as both cerebral hemispheres may be dependent upon the atheromatous carotid. Recognizing this anomaly is important and may help prevent false diagnosis of carotid dissections or high-grade carotid stenosis.

Nanorobot for Brain Aneurysm

In this paper we present how nanoelectronics should advance medicine, providing details on the teleoperated techniques and equipment design methodology necessary for the effective development of nanorobots. The platform architecture describes how to use a nanorobot for intracranial prognosis, and shows how it should be integrated for medical instrumentation. Furthermore, the current study establishes proteomics, nanobioelectronics, and electromagnetics as the basis to advance medical nanorobotics. To illustrate the proposed approach, the nanorobots must search for protein overexpression signals in order to recognize initial stages of aneurysm. An advanced nanomechatromics simulator, using a three-dimensional task-based environment, is implemented to provide an effective tool for device prototyping and medical instrumentation analysis. Thus, based on clinical data and nanobioelectronics, the proposed model offers details about how a nanorobot should help with the early detection of cerebral aneurysm.

Role of Neuroradiology in Evaluating Cerebral Aneurysms

Intracranial aneurysms are common lesions with an adult prevalence rate between one and five percent in autopsy studies 1. Fortunately, most aneurysms are small and an estimated 50 to 80 percent of all aneurysms do not rupture during the course of a person's lifetime 2. Intracranial aneurysms are considered to be sporadically acquired lesions, although a rare familiar form has been described3. Clinically, cerebral aneurysms can be silent or give rise to focal neurological symptoms or rupture leading to the dramatic event of subarachnoid haemorrhage. Nowadays the gold standard technique for the detection of cerebral aneurysms is considered to be digital subtraction angiography (DSA) offering both dynamic and morphological information on the intracranial circulation. However, DSA is relatively expensive and not widely available. DSA also carries a potential risk of transient, reversible or permanent neurological and non neurological complications even though the actual risk is much lower than is perceived 4-13` In view of this, the ideal technique to evaluate cerebral aneurysms should be non invasive, easy and quick to perform, offering high spatial resolution and yielding optimal information on aneurysm location, size of its dome and neck, any parietal abnormality, collateral arteries originating from the dome and the relation between the parent artery and surrounding vascular and/or nervous structures. Nowadays, the diagnostic work-up in patients with cerebral aneurysms or subarachnoid haemorrhage (SAH) includes several imaging techniques such as DSA, Computed Tomography Angiography (CTA) and Magnetic Resonance Angiography (MRA). Worldwide neuroradiological experience during the past 15 years has led to a consensus on the major role of CTA in evaluating patients with intracranial aneurysms. CTA is a minimally invasive, less expensive technique than DSA and MRA, easy and quick to perform and often able to provide correct information on the presence, dimensions and anatomical location of cerebral aneurysms. Volumetric acquisition allows the neuroradiologist to obtain oblique, axial and para-axial views for better display of the aneurysm dome and neck 12-19. The most important limit of CTA, widely accepted and common to most multislice CT scanners, is its dimensional constraints: most aneurysms with a dome diameter smaller than 3 mm (so-called baby aneurysms) can often be missed by CTA examination. MRA, with different acquisition techniques (Time of flight - TOF or Phase Contrast - PC), is increasingly available, but its potential role remains limited by motion and vessels artefacts, sometimes even with contrast media injection. In addition, MRA is still considered a high cost procedure, strongly affected by the already known absolute and relative contraindications and some technical difficulties (particularly when dealing with SAH patients) 20-26. In spite of these drawbacks, MRA has an important role in the follow-up of embolized cerebral aneurysms after endovascular treatment. In these cases, MRA sequences (TOF or PC), even without contrast media injection, are highly reliable in displaying major residual flow within the coil mesh or in the neck region of the aneurysm. Figure 1 A-D CT and CTA (MIP and SSD) of a basilar aneurysm.

Comparing the Accuracy of Digital Subtraction Angiography, CT Angiography and MR Angiography at Estimating the Volume of Cerebral Aneurysms

While there are many studies that compare imaging modalities in the detection of cerebralaneurysms there are no existing studies that compare two dimensional digital subtraction angiography (DSA), CT angiography (CTA) and MR angiography (MRA) in calculating the volume of cerebral aneurysms. This study will compare these imaging modalities on seven in vitro models of known volume. Seven silicone models of cerebral aneurysms were chosen representing slight variations in geometric shape and size. The volume of each model was measured by weighing the amount of water required to fill the aneurysm to the parentartery. Contrast enhanced images of the modelswere taken with DSA, CTA and MRA. The images were interpreted by four independent readers and the volumes were calculated. The measured volumes from the water weight analysis were compared to the volumes calculated from the interpreter's measurements. The accuracy of DSA, CTA and MRA were compared using the percent of absolute and true variance from the measured volume. The average percent absolute variance for DSA was 14.3%, CTA was 16.8% and MRA was 18.6%. While these differences were minimal, comparing the percent of true variance demonstrated an average variance of -1.9% for DSA, 16.1% for CTA and -15.9% for MRA. Calculating the volume of cerebral aneurysms, while increasingly important, is difficult and error prone. It is important to understand the limitations and inherent errors before relyingon calculated volumes in clinical decision making. Regardless of imaging modality, one should consider error rates of 14-19% for calculatingvolume while keeping in mind the tendencyfor CTA to overestimate volume, MRA to underestimate volume and DSA to both under and overestimate equally.

Detection of cerebral aneurysms in nontraumatic subarachnoid haemorrhage: role of multislice CT angiography in 130 consecutive patients

The leading cause of a nontraumatic subarachnoid haemorrhage is rupture of an intracranial aneurysm. The aim of this study was to assess the usefulness of multislice computed tomography angiography (CTA) in identifying and evaluating cerebral aneurysms by comparing it with intra-arterial digital subtraction angiography (DSA) and intraoperative findings. During a 20-month period (June 2004 and February 2006), 130 patients with a CT diagnosis of nontraumatic acute subarachnoid haemorrhage were prospectively recruited to this study and underwent 16-detector CTA and DSA (57 men, 73 women; mean age 59.5 years). Twenty-five patients who underwent DSA alone postclipping were excluded. CTA and DSA were evaluated by the performing radiologist to assess the presence of one or more aneurysms and their morphological characteristics. CTA detected 133 aneurysms, whereas DSA identified 134: the aneurysm missed by CTA was 2 mm in size. CTA is fast and relatively noninvasive, and its sensitivity appears similar to that of DSA in detecting and evaluating intracranial aneurysms, even those smaller than 3 mm. This study confirms the value of CTA as the primary imaging technique in subarachnoid haemorrhage, with DSA reserved for selected patients.

Venous loop mimicking middle cerebral artery bifurcation aneurysm on computed tomographic angiography—case report

Background CT angiography has been widely used for the detection of cerebral aneurysm. However, there are still limitations despite improving CT angiographic techniques. We describe the unusual case of the detection of a false-positive aneurysm on CT angiography. Case Description A 64-year-old man presented with a 14-day history of severe headache and nuchal rigidity. Brain CT demonstrated no subarachnoid hemorrhage, but cerebrospinal fluid appeared xanthochromic in 3 successive tubes after lumbar puncture. Subsequent CT angiography suggested an aneurysm at the bifurcation of the left MCA. However, at operation, prominent sylvian vein superimposed on the bifurcation of the left MCA, and there was no aneurysm. Follow-up monitoring with conventional angiography at 2 weeks showed no abnormal findings. The patient recovered uneventfully. Conclusion The case demonstrates that although CT angiography has a reportedly high specificity and sensitivity for the detection of intracranial aneurysm, careful interpretation is required to diagnose intracranial aneurysms.

Computed Tomographic Angiography for the Evaluation of Aneurysmal Subarachnoid Hemorrhage

Computed tomography (CT) followed by lumbar puncture (LP) is currently the criterion standard for diagnosing subarachnoid hemorrhage (SAH) in the emergency department (ED); however, this is based on studies involving a limited number of patients. The authors sought to assess the ability of CT angiography (CTA), a new diagnostic modality, in conjunction with CT/LP to detect SAH. Consecutive patients presenting to the ED with symptoms concerning for SAH were approached. All patients had an intravenous catheter placed and underwent a noncontrast head CT followed by CTA. Patients whose CT did not reveal evidence of SAH or other pathology underwent LP in the ED. CTAs were read within 24 hours by a neuroradiologist blinded to the patient's history. A total of 131 patients were approached, 116 were enrolled, and 106 completed the study. In six of 116 patients (5.1%), aneurysm was found on CTA with normal CT and positive findings on LP; three had a positive CTA with normal CT and LP findings (one of which had a negative cerebral angiogram), and there was one false-positive CTA. Follow-up of all 131 patients showed no previously undiagnosed intracranial pathology. In this patient population, 4.3% (5/116) were ultimately found to have an SAH and/or aneurysm. In this pilot study, CTA was found to be useful in the detection of cerebral aneurysms and may be useful in the diagnosis of aneurysmal SAH. A larger multicenter study would be useful to confirm these results.

Application of CT Angiography of Complex Cerebrovascular Lesions during Surgical Decision Making

Helical computed tomographic angiography (CTA) is a relatively new noninvasive volumetric imaging technique. Since early reports in the 1990s, CTA has rapidly improved image resolution and scan volume. Cerebral arteries can be imaged clearly, which is advantageous in the diagnosis of vascular diseases such as cerebral aneurysms, arteriovenous malformations, and cerebrovascular occlusive disease. Before attacking a cerebrovascular lesion near or in the skull base, precise preoperative knowledge of anatomic relationships between the bony and neurovascular structures is critical for obtaining successful outcomes. The sensitivity of CTA for the detection of cerebral aneurysms < or = 5 mm in diameter may be higher than that of digital subtraction angiography (DSA), with equal specificity and high interoperator reliability. With minor modification to the technique, paraclinoid vascular lesions can be depicted using CTA. We present our experience using CTA in addition to DSA to obtain important anatomic information about skull base vascular lesions that assisted in the clinical decision-making process.

Transcranial color-coded duplex sonography.

Transcranial color-coded duplex sonography (TCCS) enables the reliable assessment of intracranial stenoses, occlusions, and cross-flow through the circle of Willis without using potentially hazardous compression tests. Transpulmonary ultrasound contrast agents (UCAs) increase the number of conclusive TCCS investigations, which suggests that UCAs may provide the conclusive evaluation of intracranial arteries in most patients with ischemic cerebrovascular disease. Further, contrast-enhanced TCCS may become an important tool both for the management of acute ischemic stroke by assessing intracranial hemodynamics and the displacement and diameter changes in supratentorial ventricles. TCCS is useful for the detection and monitoring of intracranial vasospasm, may visualize larger supratentorial hematomas with subcortical location and hemorrhagic transformation of ischemic infarcts, and provides the incidental detection of cerebral aneurysms and arteriovenous malformations. Second-generation UCAs and new ultrasound machines are very likely to further increase the frequency of conclusive TCCS studies. Power-based three-dimensional, contrast-enhanced TCCS is an important further development, which would make the method much less operator dependent. Site-targeted UCAs appear to provide a new and exciting method for ultrasonic diagnosis and management of patients with ischemic cerebrovascular disease.

Application of three-dimensional CT angiography (3D-CTA) to cerebral aneurysms

BACKGROUND 3D CT angiography (3D-CTA) is a noninvasive imaging modality for cerebral aneurysms. 3D-CTA is helpful in the evaluation of the configuration of the aneurysm, the surrounding vessels, and the inside of the aneurysm dome. Clinical application of this technique in complicated large cerebral aneurysms showed that with 3D-CT endoscopic imaging, anatomical details of cerebral aneurysms such as the orifice of the aneurysm, intraluminal thrombus, and calcification of the wall could be clearly demonstrated. Using the 3D-imaging method with helical CT, virtual views of various surgical approaches can be compared preoperatively. This information was found to be very useful for determining difficult aneurysms for coil embolization or direct surgery including complicated and broad-based aneurysms. METHODS Helical CT scanners (TOSHIBA X-vigor) are used for intracranial vascular lesions. At present, nearly stereoscopic images at a pixel size of 0.35 × 0.35 × 0.4 mm are obtained by reconstruction under the following conditions: slice thickness, 0.8 mm; couch top speed, 1.0 mm/sec.; 130 kV; 220 mA; visual field, 18 cm in diameter (11 cm after extension); pitch, 0.4 mm; and opposed beam interpolation. RESULTS AND CLINICAL APPLICATION By virtual vascular 3D-CT endoscopy, the lumen of the cerebral aneurysm is displayed by the surface rendering method. Its clinical applications include 1) Demonstration of three-dimensional aneurysm morphology, including the dome and the neck region; 2) Preoperative simulation; 3) Confirmation of parent blood vessels flowing into and out of aneurysms and visualization of aneurysmal lumen calcification. Coronal and sagittal sections can demonstrate whether the branches arise from the aneurysm or aneurysmal neck. The limitation of 3D-CTA is in delineating perforating arteries that are less than 1.2 mm in diameter. The problem with virtual vascular 3D-CT endoscopic images is that endoscopic findings in the vascular wall are incomplete because of the partial volume effect and pulsation of the aneurysm and vascular wall. CONCLUSIONS Helical Scanning-CT (HES-CT) is an excellent noninvasive diagnostic modality for cerebral aneurysm detection. 3D-CT angiography has distinct advantages in evaluating aneurysms and selecting the most appropriate therapeutic modality.

Three-dimensional spiral CT angiography in the detection of cerebral aneurysm.

The value of CT angiography in the detection and evaluation of aneurysms was compared to digital subtraction angiography (DSA). Seventeen patients with acute subarachnoid hemorrhage (SAH) or with known or suspected aneurysm were investigated by means of spiral CT angiography, which included 3D reconstruction. These findings were compared with those at DSA. In 16 patients, 20 aneurysms were found; the remaining patient had an ectatic vessel that simulated an aneurysm. Seventeen of the angiographically proved aneurysms were detected at CT angiography (sensitivity 85%). One further aneurysm was identified retrospectively as the result of greater experience in the method. All the aneurysms that escaped detection at CT were 3 mm in size. All the vessels of the circle of Willis, except for the posterior communicating artery, were properly evaluated at CT angiography. Difficulties were encountered in assessing the posterior communicating artery and the extradural segment of the internal carotid artery owing to their close spatial relationship to the bony structures of the skull base and the cavernous sinus. CT angiography is a low-risk technique with a low level of invasiveness that is useful in following up known aneurysms. The 3D reconstruction yields further topographic information that helps in the planning of endovascular or surgical intervention. The facility for rotating the reconstructed vessels and displaying them from different angles is of particular value in cases difficult to assess at angiography.

Advances in the diagnosis of cerebrovascular pathology

Up to now, digital subtraction angiography (DSA) has been considered the gold standard for the detection of cerebrovascular pathology. Two noninvasive angiographic modalities have experienced an impressive recent improvement: magnetic resonance angiography (MRA) and three-dimensional computed tomographic angiography (CTA). With the latest modifications in postprocessing, the resolution of MRA has become similar to that of DSA. MRA can accurately delineate vessels less than 1 mm and aneurysms equal to or greater than 3 mm in diameter. Three-dimensional reconstructionfrom MR images can also be used for planning the surgery of cerebrovascular pathology. Three-dimensional CTA has greater resolution than MRA and has excellent correlation with DSA. CTA is extremely sensitive for the detection of cerebral aneurysms: Compared with DSA its sensitivity is about 97% and its specificity 100%. Although DSA is an invasive procedure, it still possesses greater resolution than MRA and CTA. In the hands of the skilled neuroradiologist, it carries a low risk and is the best method for the evaluation of cross-flow or vascular reserve and for postoperative control. MRA and CTA can replace DSA for the depiction of ruptured or unruptured cerebral aneurysms. As a result of the widespread use of noninvasive angiographic methods, an increasing number of unruptured aneurysms will be diagnosed. It is currently accepted that unruptured aneurysms greater than 5 mm in diameter should be surgically clipped. The wrapping technique is not generally considered to be an effective treatment of cerebral aneurysms.

Three-dimensional spiral CT angiography in the detection of cerebral aneurysm

Three-dimensional spiral CT angiography in the detection of cerebral aneurysm

Three-dimensional computed tomographic angiography in detection of cerebral aneurysms in acute subarachnoid hemorrhage.

Three-dimensional computed tomographic angiography (CTA) is a recently developed imaging modality. We demonstrate the value of this noninvasive method in replacing digital subtraction angiography (DSA) in the detection of aneurysms of the circle of Willis in patients with subarachnoid hemorrhage admitted to our institution. A helical acquisition was performed for computed tomographic scans obtained for 120 patients with a 1 mm per second table speed and a 1-mm collimation, 1:1 pitch. Axial source images were transferred on a console Advantage Windows workstation (General Electric, Milwaukee, WI) and CTA was obtained using maximum intensity projection reconstruction. All patients had undergone DSA of the circle of Willis (80 patients preoperatively and 40 postoperatively). A total of 129 aneurysms were detected in 107 patients. Three-dimensional CTA disclosed nothing abnormal in 13 patients. Ninety-two patients sustained one aneurysm, 10 patients sustained two, 3 patients sustained three, and 2 patients sustained four. All results were confirmed by DSA. In two cases, aneurysms of the middle cerebral artery were defected by CTA but not by DSA. When using angiographic views, the aneurysm was always masked by a branch of the middle cerebral artery. The sensitivity of three-dimensional CTA is comparable with that of DSA, and its specificity is 100%. Because CTA is simple, quick, noninvasive, and reliable, we think that it can eventually replace DSA.

Optimization of parameters for the detection of cerebral aneurysms: CT angiography of a model.

To optimize parameters with computed tomographic angiography for the detection of cerebral aneurysms. Model aneurysms were placed randomly at various branch points and scanned multiple times with spiral technique. The final analysis included 63 branch points and 22 aneurysms. Each spiral scan used a different parameter combination. Collimation ranged from 1.5 to 4.0 mm and pitch ranged from 1:1 to 1.5:1. Images were constructed with shaded surface display (SSD) and maximum intensity projection (MIP) algorithms and were interpreted by three readers for the presence or absence of aneurysm. The receiver operating characteristic (ROC) curve area for 1.5-mm collimation was greater than those of 3- or 4-mm collimation (P < .01 and P < .001, respectively). There was no statistically significant difference in the ROC curve areas between 3- and 4-mm collimation (P = .37). There was no statistically significant decrease in ROC curve area when increasing pitch from 1:1 to 1.5:1 for any value of collimation (P = .96). For all parameter combinations the ROC curve areas for SSD images was greater than that of MIP images (P < .0001). For cerebral aneurysm detection, narrow collimation is superior to wider collimation. Mild increases in pitch do not substantially degrade diagnostic accuracy. SSD offers improved diagnostic accuracy over MIP display in this model.

Negative MRI versus real disease

A 76-year-old diabetic woman presented with progressive binocular vertical diplopia and right eye pain. Examination revealed a pupil-involving partial right third cranial nerve palsy, with development of anisocoria over the course of several hours. MRI of the brain showed no mass lesion. MRA, even with retrospective review of the images, failed to clearly identify a 1 cm right posterior communicating artery aneurysm detected by subsequent conventional cerebral angiography. While MRA has been reported to be highly sensitive in cerebral aneurysm detection at some centers, other investigators have indicated less favorable data. Standardized protocols for data acquisition and meticulous attention to proper post-processing and image interpretation are essential if MRA is to supplant invasive arteriography. Currently, conventional (x-ray) angiography remains the gold standard for aneurysm detection, while MRA possesses excellent potential in this regard.

Transcranial color-coded duplex sonography in cerebral aneurysms.

Diagnosis and successful therapy before rupture of cerebral aneurysms would be most desirable in view of the high mortality and morbidity rates of aneurysmal subarachnoid hemorrhage. Using transcranial color-coded duplex sonography, we studied radiologically proven cerebral aneurysms to define ultrasonographic criteria and sensitivity for their diagnosis and detection. Twenty-nine consecutive patients with 30 radiologically proven cerebral aneurysms were prospectively examined using transcranial color-coded duplex sonography. The sonographer was aware of cerebral computed tomographic and magnetic resonance imaging findings but was blinded to the results of cerebral angiography. Ultrasonographic findings for aneurysms studied were as follows: (1) Scanning planes that transsected approximately mid-aneurysm showed a round or oval mass that was divided by a "separation zone" into red and blue areas. (2) The "separation zone" was characterized by dark or no colors. (3) Peripheral scanning planes showed monochromatic images. (4) No turbulence was found. (5) No spontaneous fluctuations were detected. Twenty-three of 27 (85%) nonthrombosed aneurysms with a diameter of 6 to 25 mm were identified. The walls and three thrombosed and four nonthrombosed aneurysms (mean diameter, 5 mm) were missed. Transcranial color-coded duplex sonography can provide the diagnosis of nonthrombosed aneurysm using the above-cited criteria because of its capacity to reveal flow phenomena. It is not the method of choice in the search for aneurysms because small and thrombosed aneurysms are missed. Careful visual inspection of the intracranial arteries to permit incidental detection of cerebral aneurysms should be part of every transcranial color-coded duplex examination.

Noninvasive detection of intracranial vascular lesions by recording blood flow sounds.

Transorbital blood flow sound recordings have the potential to be used for noninvasive detection of cerebral aneurysms and arteriovenous malformations. We describe our system and experience in detecting intracranial cerebrovascular disease. We investigated the noninvasive detection of intracranial vascular lesions by recording and analyzing the intracranial blood flow sounds. A new small transducer was placed on the unilateral eyelid to record the intracranial blood flow sounds, which were amplified and converted to digital data at a sampling frequency of 2000 Hz to provide a spectral analysis. No spectral peaks were recorded in 30 healthy adults. Sharp peaks were recorded in 12 of 15 patients with unclipped aneurysms, and broad peaks were recorded in two patients with vasospasm after aneurysmal clipping and in all patients with severe intracranial internal carotid artery stenosis. This noninvasive technique has the potential to be very useful in the detection of intracranial cerebrovascular disease, including aneurysm and arterial stenosis, and could be used in mass screening examinations.

Screening of Cerebral Aneurysm by Transcranial Doppler Ultrasonography

The significance of transcranial Doppler ultrasonography (TCD) in the detection of cerebral aneurysm was studied in twenty patients with subarachnoid hemorrhage. Transcranial Doppler arteriography (TCDA) and transcranial Doppler Tomography (TCDT) were used for evaluation in this study. In five of twenty patients (25%), turbulent flow in the aneurysm of the middle cerebral artery and internal carotid artery was detected. The diameter of the aneurysms was larger than 10 mm, except for one patient with a small aneurysm. The detection rate of cerebral aneurysm was the highest when TCDT was used.Cerebral aneurysms can be detected by conventional TCD, but the detection rate is not satisfactory compared with other neuroimaging modalities.Further development of TCD devices is needed for practical screening of an unruptured cerebral aneurysm.