What is the most sensitive non-invasive imaging strategy for the diagnosis of intracranial aneurysms?

Association Between Flow Acceleration in the Carotid Artery and Intracranial Aneurysms

OBJECTIVES

In physiologic pulsatile flow, velocity acceleration is an independent factor determining wall shear stress experienced by the vascular endothelium. The purpose of this study was to evaluate Doppler indices of systolic velocity acceleration in extracranial cerebral vessels and the occurrence of intracranial aneurysms.

METHODS

We reviewed medical records and 3.0-T brain magnetic resonance imaging with 3-dimensional time-of-flight magnetic resonance angiography of 1323 adults who underwent health checkups from June 2006 to November 2011, in whom 53 intracranial aneurysms were identified in 45 patients. Doppler ultrasound parameters of the carotid and vertebral arteries were analyzed in these 45 patients with aneurysms and compared with another 45 control participants matched for age and sex. We defined the maximum systolic acceleration (ACC_max ) as the maximum slope of the early phase of systolic acceleration on the Doppler waveform and the maximum acceleration index (AI_max ) as the ratio of the ACC_max and peak systolic velocity.

RESULTS

The Doppler analysis showed a significantly increased AI_max and ACC_max in the common carotid artery (CCA), internal carotid artery, and vertebral artery in the aneurysm group. A cutoff 13.89 s^-1 for the AI_max of the CCA had sensitivity of 80% with a negative predictive value of 99% for intracranial aneurysms.

CONCLUSIONS

This study suggests that the AI_max of the CCA with a cutoff of 13.89 s^-1 may be an alternative to 3-dimensional time-of-flight magnetic resonance angiography or computed tomographic angiography as a screening tool for intracranial aneurysms. Further prospective studies are needed to validate the diagnostic performance and cost-effectiveness of these indices for screening.

Meta-analysis of computed tomography angiography versus magnetic resonance angiography for intracranial aneurysm

BACKGROUND

Whether the diagnosis value of computed tomography angiography (CTA) for intracranial aneurysm is in accordance with magnetic resonance angiography (MRA) remains inconclusive. This meta-analysis aims to synthesize relevant studies to compare the diagnostic efficacies of the 2 methods.

METHODS

Potentially relevant studies were selected through PubMed, Embase, Wanfang, Chongqing VIP, and China National Knowledge Infrastructure databases by using the core terms "computer tomography angiography" (CTA) and "magnetic resonance angiography" (MRA) and "intracranial aneurysm*" in the titles, abstracts, and keywords of the articles. Quality Assessment for Diagnostic Accuracy Studies (QUADAS-2) was utilized to evaluate the quality. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were count. Summary receiver operating characteristic curves (SROC) and area under the curve (AUC) were used to summarize the overall diagnostic performance. Statistical analyses were performed by Stata version 12.0 and MetaDisc 1.4 software.

RESULTS

Ten articles were identified in this current paper. For CTA, the pooled estimates of diagnostic parameters for intracranial aneurysm were as follows: sensitivity, 0.84 (95%CI = 0.81-0.86); specificity, 0.85 (95%CI = 0.79-0.89); PLR, 4.09 (95%CI = 2.45-6.81); NLR, 0.18 (95%CI = 0.11-0.28); DOR, 23.74 (95%CI = 10.49-53.74); AUC, 0.90, respectively. For MRA, the pooled estimates of diagnostic parameters for intracranial aneurysm were as follows: sensitivity, 0.80 (95%CI = 0.77-0.83); specificity, 0.87 (95%CI = 0.82-0.91); PLR, 3.61 (95%CI = 1.72-7.55); NLR; 0.27 (95%CI = 0.21-0.35); DOR, 16.77 (95%CI = 7.38-38.11); AUC, 0.87, respectively. No significant difference was found the AUC value between CTA and MRA for intracranial aneurysm (Z = 0.828, P > .05).

CONCLUSION

This comprehensive meta-analysis demonstrated that the diagnosis value of CTA was in accordance with MRA for intracranial aneurysm. However, considering the limitation of sample size, the results should be treated with caution.

Non-enhanced MR imaging of cerebral aneurysms: 7 Tesla versus 1.5 Tesla

PURPOSE

To prospectively evaluate 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) in comparison to 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of unruptured intracranial aneurysms (UIA).

MATERIAL AND METHODS

Sixteen neurosurgical patients (male n = 5, female n = 11) with single or multiple UIA were enrolled in this trial. All patients were accordingly examined at 7 Tesla and 1.5 Tesla MRI utilizing dedicated head coils. The following sequences were obtained: 7 Tesla TOF MRA, 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced MPRAGE. Image analysis was performed by two radiologists with regard to delineation of aneurysm features (dome, neck, parent vessel), presence of artifacts, vessel-tissue-contrast and overall image quality. Interobserver accordance and intermethod comparisons were calculated by kappa coefficient and Lin's concordance correlation coefficient.

RESULTS

A total of 20 intracranial aneurysms were detected in 16 patients, with two patients showing multiple aneurysms (n = 2, n = 4). Out of 20 intracranial aneurysms, 14 aneurysms were located in the anterior circulation and 6 aneurysms in the posterior circulation. 7 Tesla MPRAGE imaging was superior over 1.5 and 7 Tesla TOF MRA in the assessment of all considered aneurysm and image quality features (e.g. image quality: mean MPRAGE7T: 5.0; mean TOF7T: 4.3; mean TOF1.5T: 4.3). Ratings for 7 Tesla TOF MRA were equal or higher over 1.5 Tesla TOF MRA for all assessed features except for artifact delineation (mean TOF7T: 4.3; mean TOF1.5T 4.4). Interobserver accordance was good to excellent for most ratings.

CONCLUSION

7 Tesla MPRAGE imaging demonstrated its superiority in the detection and assessment of UIA as well as overall imaging features, offering excellent interobserver accordance and highest scores for all ratings. Hence, it may bear the potential to serve as a high-quality diagnostic tool for pretherapeutic assessment and follow-up of untreated UIA.

Diagnostic Accuracy of Magnetic Resonance Angiography for Detection of Intracranial Aneurysms in Patients with Acute Subarachnoid Hemorrhage; A Comparison to Digital Subtraction Angiography

OBJECTIVES

To determine the diagnostic accuracy of magnetic resonance angiography (MRA) compared to intra-arterial digital subtraction angiography (DSA) in detection of intracranial aneurysms in those suffering from acute subarachnoid hemorrhage (SAH).

METHODS

This observational diagnostic study was performed at a tertiary teaching hospital and reference center in Shiraz, Iran. We included 55 patients who presented to our center with the diagnosis of acute SAH. All the patients underwent MRA and DSA during their hospital course in order to detect the intracranial aneurysms. The time-of-flight MRA protocol was used and the results were compared to the results of DSA as the gold standard test. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for MRA.

RESULTS

The mean age of the patients was 46.3 ± 7.9 including 26 (47.3%%) men and 29 (52.7%) women. In 46 patients, 51 intracranial aneurysms were diagnosed by DSA (5 patients had two aneurysms). No evidence of intracranial aneurysm was found in 9 patients with subarachnoid hemorrhage. MRA correctly identified 42 of the 51 aneurysms (sensitivity 82%) and missed 9 small aneurysms (less than 10 mm). MRA revealed one false- positive finding, resulting in a specificity of 88.8%. The PPC and NPV for MRA were 97% and 47%, respectively. The diagnostic accuracy per aneurysm was 0.83 for MRA.

CONCLUSION

High sensitivity and specificity of MRA compared to DSA in diagnosis of intracranial aneurysms in those with acute SAH indicate that MRA could be reliably used as a diagnostic tool for this purpose. However we cannot recommend it as a routine substitute for DSA before surgery.

Intracranial aneurysm in childhood and interrupted aortic arch

BACKGROUND

Intracranial aneurysms are very rare in children. Headache and nausea/vomiting are the most prominent clinical findings. The only effective treatment is obliteration of aneurysm by surgical or endovascular techniques. Interrupted aortic arch is also a rare, congenital cardiovascular malformation characterized by the lack of continuity between the ascending and descending thoracic aorta. Aortic interruption is an uncommon cause of intracranial aneurysm. The course of disease is lethal unless effective collateral flow develops. Long-term survival may be possible with surgical repair.

METHOD

We report on a 17-year-old boy affected with interrupted aortic arch disease and associated multiple intracranial aneurysms. Both aneurysms clipped successfully. After patient had recovered, he referred to cardiovascular surgery for further treatment.

CONCLUSION

Surgical or endovascular obliteration remains the main therapy for intracranial aneurysms. Accompanying systemic diseases such as interrupted aortic arch challenge the management of both diseases.

Iatrogenic intracranial aneurysms in childhood: case-based update

PURPOSE

Iatrogenic aneurysms are very rare in children. Characteristic clinical manifestations are variable and asymptomatic course is possible especially for fusiform dilatation of internal carotid artery. Even though radiological diagnosis is easy, the management of iatrogenic intracranial aneurysm is still a subject for discussion.

METHODS

Fusiform dilatations of internal carotid artery were diagnosed on three pediatric patients during follow-up imaging after primary surgery for suprasellar-parasellar tumor. All patients were asymptomatic. Conservative treatment was proposed because the lesion did not show any progression in subsequent examinations. Patients are stable under conservative treatment.

CONCLUSIONS

Iatrogenic aneurysm may have an unusual presentation and their therapy still remains unclear. Fusiform dilatation of internal carotid artery rarely causes symptoms and there is no published paper of subarachnoid bleeding. Treatment would be difficult, since the main arterial branches arise from the dilated carotid segment. Conservative treatment is a choice only if aneurysm has no progression or in case of spontaneous healing. Intervention should be performed only in case of progression or if the aneurysm becomes symptomatic.

A mathematical model of utility for single screening of asymptomatic unruptured intracranial aneurysms at the age of 50 years

BACKGROUND

Although rupture of intracranial aneurysms carries high mortality and morbidity rates, the clinical and financial benefit of screening certain high-risk groups is uncertain. We designed a mathematical model to interrogate the clinical benefit and cost-effectiveness of screening.

METHODS

A decision tree analysis model was used to calculate the outcome and cost of two scenarios applied to the same population: one-off screening for intracranial aneurysms versus not screening. Each scenario had an associated gain or loss of Quality Adjusted Life Years (QALY) and cost; the difference between the two scenarios was calculated. The variable inputs were the aneurysm prevalence and risk of rupture after 5 years. Sensitivity analyses were performed to determine the effects of altering various factors on outcomes.

RESULTS

Screening of the asymptomatic general population results in a QALY loss, equating to a negative clinical impact. The threshold 5-year risk of rupture at which screening resulted in a gain in QALYs was 13 %. This held true for any prevalence between 1 and 25 %. Risk of rupture had a greater impact on outcome than prevalence. Halving the risk of intervention (either surgery or coiling) reduced the threshold 5-year risk of rupture at which screening results in gain of QALYs to 6 %. The age of screening also had important effects on outcome.

CONCLUSIONS

The QALY benefit and cost-effectiveness of screening are most sensitive to the 5-year risk of rupture. Screening is beneficial only in populations with a high risk of rupture; this should be the focus of future research.

[Development of new intracranial saccular aneurysms]

Newly formed aneurysms developing from a cerebral vessel which had appeared to be normal in a previous angiographic study are very rare. Four cases of angiographically documented newly developed saccular aneurysms are described in this report. In all four patients, the new aneurysms were symptomatic, causing subarachnoid hemorrhage (SAH). Repeat angiography, performed after the second SAH, revealed new aneurysms that were not demonstrated on initial angiograms after the first SAH. They were clipped with good postoperative course. Our observations and literature data suggest that some patients with SAH need further neuroradiological followup. The presence of the risk factors and age of the patient should be taken into consideration.

An approach to the patient with painful ophthalmoplegia, with a focus on Tolosa-Hunt syndrome

The differential diagnosis of painful ophthalmoplegia is extensive and consists of numerous sinister etiologies, including neoplasms (ie, primary intracranial tumors, local or distant metastases), vascular (eg, aneurysm, carotid dissection, and carotid-cavernous fistula), inflammatory (ie, orbital pseudotumor, giant cell arteritis, sarcoidosis, and Tolosa-Hunt syndrome), and infectious etiologies (ie, fungal and mycobacterial), as well as other miscellaneous conditions (ie, ophthalmoplegic migraine and microvascular infarcts secondary to diabetes). A systematic approach to the evaluation of painful ophthalmoplegia can lead to prompt recognition of serious disorders that can be associated with significant morbidity or mortality if left untreated. Inflammatory conditions such as Tolosa-Hunt syndrome and orbital pseudotumor are highly responsive to corticosteroids but should be diagnoses of exclusion.

Subarachnoid haemorrhage

Subarachnoid haemorrhage accounts for only 5% of strokes, but occurs at a fairly young age. Sudden headache is the cardinal feature, but patients might not report the mode of onset. CT brain scanning is normal in most patients with sudden headache, but to exclude subarachnoid haemorrhage or other serious disorders, a carefully planned lumbar puncture is also needed. Aneurysms are the cause of subarachnoid haemorrhage in 85% of cases. The case fatality after aneurysmal haemorrhage is 50%; one in eight patients with subarachnoid haemorrhage dies outside hospital. Rebleeding is the most imminent danger; a first aim is therefore occlusion of the aneurysm. Endovascular obliteration by means of platinum spirals (coiling) is the preferred mode of treatment, but some patients require a direct neurosurgical approach (clipping). Another complication is delayed cerebral ischaemia; the risk is reduced with oral nimodipine and probably by maintaining circulatory volume. Hydrocephalus might cause gradual obtundation in the first few hours or days; it can be treated by lumbar puncture or ventricular drainage, dependent on the site of obstruction.

Enlargement to a saccular aneurysm and subsequent rupture of infundibular widening of posterior communicating artery

A small dilatation known as infundibular widening (IFw) is frequently seen (7%-25%) on the posterior communicating artery (PComA) at its origin from the internal carotid artery. Development and subsequent rupture of an aneurysm on a previously radiographically demonstrated IFw has rarely been documented. We present two patients who suffered from subarachnoid hemorrhage (SAH). Initial cerebral angiography demonstrated IFw on PComA. They were readmitted to the hospital 9 and 11 years later, after a new SAH. Repeated cerebral angiography revealed an aneurysm arising from the site where the IFw had been seen previously in both cases. The aneurysms were clipped with favorable outcome. This report adds two new cases documenting enlargement of PComAIFw into an aneurysm. Patients with PComAIFw, especially those who have experienced SAH, should be considered for periodic follow-up to rule out the development of an aneurysm over time.

Current Diagnostic Modalities for Intracranial Aneurysms

Aneurysm diagnosis has evolved considerably over the last years. Technological advances have brought CT angiography and MR angiography to the forefront of ruptured and nonruptured intracranial aneurysm diagnosis. This article highlights current diagnostic modalities for intracranial aneurysms.

Computed tomographic angiography for the evaluation of aneurysmal subarachnoid hemorrhage

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Traumatic cerebral aneurysm formation following ventriculoperitoneal shunt insertion

INTRODUCTION

Iatrogenic intracranial aneurysms are rare in children.

CASE REPORT

A 15-year-old girl presented in coma with a fixed dilated left pupil six weeks following removal of a long-standing left-sided ventriculoperitoneal shunt. Computed tomography (CT) and cerebral angiography revealed a left temporoparietal intracerebral haemorrhage with a fusiform distal middle cerebral artery aneurysm. The patient underwent image-guided localisation of the aneurysm to enable evacuation of the haemorrhage and resection of the fusiform aneurysm.

CONCLUSION

A high index of suspicion is required for diagnosis and early treatment to prevent unnecessary morbidity and mortality.

Painful ophthalmoplegia: Overview with a focus on tolosa-hunt syndrome

Painful ophthalmoplegia is an important presenting complaint to emergency departments, ophthalmologists, and neurologists. The etiological differential diagnosis of painful ophthalmoplegia is extensive and consists of numerous sinister etiologies including vascular (eg, aneurysm, carotid dissection, carotid-cavernous fistula), neoplasms (eg, primary intracranial tumors, local or distant metastases), inflammatory conditions (eg, orbital pseudotumor, sarcoidosis, Tolosa-Hunt syndrome), infectious etiologies (eg, fungal, mycobacterial), and other conditions (eg, microvascular infarcts secondary to diabetes, ophthalmoplegic migraine, giant cell arteritis). A systematic approach to the evaluation of painful ophthalmoplegia can lead to prompt recognition of serious disorders that if left untreated, can be associated with significant morbidity or mortality. Inflammatory conditions such as Tolosa-Hunt syndrome and orbital pseudotumor are highly responsive to corticosteroids, but should be diagnoses of exclusion.

Geometrical accuracy and fusion of multimodal vascular images: A phantom study

The aim of this work was to compare the geometrical accuracy of x-ray angiography, magnetic resonance imaging (MRI), x-ray computed tomography (XCT), and ultrasound imaging (B-mode and IVUS, or intravascular ultrasound) for measuring the lumen diameters of blood vessels. An image fusion method was also developed to improve these measurements. The images were acquired from a phantom that mimic vessels of known diameters. After acquisition, the multimodal images were coregistered by manual alignment of fiducial markers, and then by maximization of mutual information. The fusion method was performed by means of a fuzzy logic modeling approach followed by a combination process based on a possibilistic theory. The results showed (i) the better geometrical accuracy of XCT and IVUS compared to the other modalities, and (ii) the better accuracy and smaller variability of fused images compared to single modalities, with respect to most diameters investigated. For XCT, the error varied from 0.4% to 5.4%, depending on the vessel diameter that ranged from 0.93 to 6.24 mm. For IVUS, the error ranged from -0.3% to 1.7% but the smallest vessel (0.93 mm) could not be investigated because of the probe size. Compared to others fusion schemes, the XCT-MRI fused images provided the best results for both accuracy (from -1.6% to 0.2% for the three largest vessels) and robustness (mean relative error of 1.9%). To conclude, this work underlined both the usefulness of the multimodality vascular phantom as a validation tool and the utility of image fusion in the vascular context.

A rapid noninvasive method to visualize ruptured aneurysms in the emergency room: three-dimensional power Doppler imaging

OBJECT

Three-dimensional (3D) power Doppler ultrasonography imaging provides a rapid, noninvasive visualization of ruptured intracranial aneurysms, including their relationship to other vascular structures.

METHODS

The authors used transcranial 3D power Doppler imaging in the emergency room to examine patients with acute subarachnoid hemorrhage. In all patients, the ruptured aneurysm was rapidly located with 3D power Doppler imaging. Conventional x-ray angiography confirmed both the ultrasonography-based diagnosis and the location of aneurysmal bleeding.

CONCLUSIONS

These preliminary results indicate that 3D power Doppler imaging is a rapid, noninvasive screening method for the visualization of ruptured aneurysms.

Unruptured intracranial aneurysms: benign curiosity or ticking bomb?

15 years ago, the treatment of incidentally discovered intracranial aneurysms was straightforward with a good evidence base behind it. When intracranial aneurysms were identified, people were referred to neurosurgeons who would offer surgical repair if the patient was in reasonable health and had a good life expectancy. Since that time, several studies have given contradictory evidence for what should be done with these lesions, and a new technique for the repair of aneurysms, endovascular coil embolisation, has been developed. Here we review the research and make several recommendations. First, incidentally discovered aneurysms in the anterior circulation less than 7 mm in size in people with no personal or family history of subarachnoid haemorrhage should be left untreated. Second, people with remaining life expectancy of less than 20 years or so (ie, those over age 60 years) should be informed that from a statistical point of view the benefits of treatment do not outweigh the risks. Third, in all other cases treatment with surgical clipping or coil embolisation should be advised. And finally, if surgical treatment is not feasible then medical hypotensive treatment may be a viable alternative.

Detection of Intracranial Aneurysms: Multi–Detector Row CT Angiography Compared with DSA

PURPOSE

To prospectively compare the effectiveness of multi-detector row computed tomographic (CT) angiography with that of conventional intraarterial digital subtraction angiography (DSA) used to detect intracranial aneurysms in patients with nontraumatic acute subarachnoid hemorrhage.

MATERIALS AND METHODS

Thirty-five consecutive adult patients with acute subarachnoid hemorrhage were recruited into the institutional review board-approved study and gave informed consent. All patients underwent both multi-detector row CT angiography and DSA no more than 12 hours apart. CT angiography was performed with a multi-detector row scanner (four detector rows) by using collimation of 1.25 mm and pitch of 3. Images were interpreted at computer workstations in a blinded fashion. Two radiologists independently reviewed the CT images, and two other radiologists independently reviewed the DSA images. The presence and location of aneurysms were rated on a five-point scale for certainty. Sensitivity and specificity were calculated independently for image interpretation performed by the two CT image readers and the second DSA image reader by using the first DSA reader's interpretation as the reference standard.

RESULTS

A total of 26 aneurysms were detected at DSA in 21 patients, and no aneurysms were detected in 14 patients. Sensitivity and specificity for CT angiography were, respectively, 90% and 93% for reader 1 and 81% and 93% for reader 2. The mean diameter of aneurysms detected on CT angiographic images was 4.4 mm, and the smallest aneurysm detected was 2.2 mm in diameter. Aneurysms that were missed at initial interpretation of CT angiographic images were identified at retrospective reading.

CONCLUSION

Multi-detector row CT angiography has high sensitivity and specificity for detection of intracranial aneurysms, including small aneurysms, in patients with nontraumatic acute subarachnoid hemorrhage.

Screening for intracranial aneurysms in autosomal dominant polycystic kidney disease. Review Article

Screening patients with autosomal dominant polycystic kidney disease (ADPKD) for asymptomatic intracranial aneurysms has been proposed as a method of reducing the morbidity and mortality associated with aneurysm rupture. However, recent studies have shown lower spontaneous rupture rates of small aneurysms and higher risks of significant complications with interventions than previously reported. Risk-benefit analysis has not demonstrated any benefit of screening ADPKD patients without a history of subarachnoid haemorrhage (SAH) for intracranial aneurysms, and has suggested that screening might cause harm.

Biomathematical modeling and analysis of blood flow in an intracranial aneurysm

The basic hypothesis of this study is that the intracranial aneurysm may enlarge and rupture due to dynamic instabilities of the blood flow and pressure inside the aneurysm. The specific question we attempted to answer is: which parameter(s) of aneurysmal geometry can serve as a reliable predictor(s) for aneurysmal rupture? We consider an idealized cylindrical aneurysm of the human common carotid artery and develop a mathematical model of blood flow through a normal artery and aneurysm connected in series. The mathematical model is nonlinear. It comprises nonlinear rheological properties of the normal artery and aneurysmal materials, and the inertial and resistance properties of the blood flow. The model equations were solved numerically and analyzed by methods of nonlinear dynamics. The critical aneurysmal diameter (CAD) is defined as a boundary point between the stable and unstable states of the model equations. The results confirm that a limit point of flow stability can occur only for a certain difference between aneurysmal and artery radii which are pre-disposed from a difference in their material properties. It was shown that CAD is dependent on both aneurysmal length and age of patient. Finally, the results suggest that the ratio between aneurysmal and normal artery diameters is a more reliable predictor of the aneurysmal rupture than the diameter alone. We conclude that an aneurysm diameter twice that of the normal artery could be dangerous.

Multislice computerized tomography angiography in the evaluation of intracranial aneurysms: a comparison with intraarterial digital subtraction angiography

OBJECT

The goal of this study was to assess the diagnostic accuracy of computerized tomography (CT) angiography performed with the aid of multislice technology (MSCT angiography) in the investigation of intracranial aneurysms, by comparing this method with intraarterial digital subtraction (IADS) angiography.

METHODS

Fifty consecutive adult patients, who successively underwent MSCT angiography (four rows) and IADS angiography of intracranial vessels, were prospectively identified. The MSCT angiography studies consisted of 1.25-mm slices, with 0.8-mm reconstruction intervals, a pitch of 0.75, and timing determined by a test bolus. Two neuroradiologists, who were blinded to the initial interpretation of the MSCT angiograms as well as to those of the IADS angiograms, independently reviewed the MSCT angiograms for the detection and characterization of intracranial aneurysms. Forty-nine intracranial aneurysms were identified in 40 patients; 33 of these lesions were responsible for subarachnoid hemorrhage. The sensitivity, specificity, and accuracy of MSCT angiography in the detection of intracranial aneurysms were 94.8, 95.2, and 94.9%, respectively, on a per-aneurysm basis and 99, 95.2, and 98.3%, respectively, on a per-patient basis. Interobserver agreement was 98%. There was an excellent correlation between aneurysm size assessed using MSCT angiography and that determined by IADS angiography (slope = 0.916, r = 0.877, p < 0.001); however, 2 mm stood as the cutoff size below which the sensitivity of MSCT angiography was statistically lower. That method displayed great accuracy in characterizing the morphological characteristics of the aneurysm.

CONCLUSIONS

Multislice CT angiography is an accurate and robust noninvasive screening test for intracranial aneurysms. It performs better than that reported for single-slice CT angiography. Introduction of eight- and especially 16-row MSCT angiography will provide further progression through thinner slices, a lower pitch, and a purely arterial phase.

Computed tomography scan of the head in patients with migraine or tension-type headache

A retrospective study was performed in order to evaluate the frequency of abnormalities found by computed tomography (CT) scan of the head in 78 patients with migraine or tension-type headache. In the present study CT scan was normal in 61.5% of the patients with migraine or tension-type headache. A number of abnormalities were encountered in more than one third of the patients studied, including inflammatory sinus disease (19.2%), cysticercosis (3.9%), unruptuted cerebral aneurysm (2.6%), basilar impression (2.6%), intracranial lipoma (2.6%), arachnoid cyst (2.6%), empty sella (2.6%), intracranial neoplasm (2.6%), and others (2.6%). None of these lesions were symptomatic or responsible by the headache picture, therefore, considered incidental findings. In conclusion, the fortuitous encounter of some abnormalities on CT scan of the head is often higher than what we could predict in patients suffering migraine or tension-type headache. We briefly discuss clinical, epidemiologic, and practical management of some of the abnormalities detected by CT scan as well as the indication to request a neuroimaging investigation.

Intracranial vascular calcifications mimicking small saccular aneurysms on CT angiography: a technical note and case description

The authors describe a case of intracranial vascular calcifications that mimicked small saccular aneurysms on CT angiography (CTA). The density of two vascular calcifications was visually similar to that of contrast in the parent vessel, making them indistinguishable from aneurysmal outpouchings. Comparison of the CTA with the non-contrast head CT (NCCT) was critical to distinguish low-density calcifications from tiny aneurysms.