Sixty-four-row multislice computed tomographic angiography in the diagnosis and characterization of intracranial aneurysms: comparison with 3D rotational angiography

Neurovascular Imaging with Ultra-High-Resolution Photon-Counting CT: Preliminary Findings on Image-Quality Evaluation

BACKGROUND AND PURPOSE

The first-generation photon-counting detector CT was recently introduced into clinical practice and represents a promising innovation in high-resolution CT imaging. The purpose of this study was to assess the image quality of ultra-high-resolution photon-counting detector CT compared with energy-integrating detector CT and to explore different reconstruction kernel sharpness levels for the evaluation of intracranial aneurysms.

MATERIALS AND METHODS

Ten patients with intracranial saccular aneurysms who had previously undergone conventional energy-integrating detector CT were prospectively enrolled. CT angiograms were acquired on a clinical dual-source photon-counting detector CT in ultra-high-resolution mode and reconstructed with 4 vascular kernels (Bv36, Bv40, Bv44, Bv48). Quantitative and qualitative image-quality parameters of the intracranial arteries were evaluated. For the quantitative analysis (image noise, SNR, contrast-to-noise ratio), ROIs were manually placed at standard anatomic intracranial and extracranial locations by 1 author. In addition, vessel border sharpness was evaluated quantitatively. For the qualitative analysis, 3 blinded neuroradiologists rated photon-counting detector CT and energy-integrating detector CT image quality for the evaluation of the intracranial vessels (ie, the aneurysms and 9 standard vascular branching locations) on a 5-point Likert-type scale. Additionally, readers independently selected their preferred kernel among the 4 kernels evaluated on photon-counting detector CT.

RESULTS

In terms of quantitative image quality, Bv48, the sharpest kernel, yielded increased image noise and decreased SNR and contrast-to-noise ratio parameters compared with Bv36, the smoothest kernel. Compared with energy-integrating detector CT, the Bv48 kernel offered better quantitative image quality for the evaluation of small intracranial vessels (P < .001). Image-quality ratings of the Bv48 were superior to those of the energy-integrating detector CT and not significantly different from ratings of the B44 reconstruction kernel. When comparing side by side all 4 photon-counting detector reconstruction kernels, readers selected the B48 kernel as the best to visualize the aneurysms in 80% of cases.

CONCLUSIONS

Ultra-high-resolution photon-counting detector CT provides improved image quality for neurovascular imaging. Although the less sharp kernels provided superior SNR and contrast-to-noise ratio, the sharpest kernels delivered the best subjective image quality on photon-counting detector CT for the evaluation of intracranial aneurysms.

Vein of Galen aneurysmal malformation associated with brain abscess: A computed tomography case report

Vein of Galen malformation (VGM) is a rare congenital, uncommon intracerebral vascular anomaly rarely complicated with the development of brain abscess as secondary to primary infection or after endovascular treatment. We report a very rare finding of a vein of Galen aneurysm associated with a large brain abscess at the time of diagnosis. A 12-year-old boy with a high-grade fever, severe headache, and recurrent episodes of convulsions came into the radiology department of Kassala Advanced Diagnostic Center. On a Siemens 16-slice scanner, brain non-contrast enhanced computed tomography (NECT) and contrast enhanced CT (CECT) was used to determine the source of the acute headache and convulsions which revealed a right frontal peripherally enhancing cystic lesion measuring 5.7 × 4.7 × 5.3 cm2 surrounded by massive vasogenic edema causing mass effect with midline shift to the left side by 1.5 cm suggestive of brain abscess. There is evidence of another avidly enhancing lesion seen within the third ventricle continuous with a straight sinus surrounded by extensive vascular loops consistent with an aneurysm of the vein of Galen, it was causing compression of the cerebral aqueduct with upstream mild hydrocephalus with dilated both lateral ventricles. Late presentation, diagnosis, and treatment also lead to an increase in the morbidities and mortalities of such case conditions. Urgent intervention should be considered for better outcomes.

ACR Appropriateness Criteria® Cerebrovascular Diseases-Aneurysm, Vascular Malformation, and Subarachnoid Hemorrhage

Cerebrovascular disease is a broad topic. This document focuses on the imaging recommendations for the varied clinical scenarios involving intracranial aneurysms, vascular malformations, and vasculitis, which all carry high risk of morbidity and mortality. Additional imaging recommendations regarding complications of these conditions, including subarachnoid hemorrhage and vasospasm, are also covered. While each variant presentation has unique imaging recommendations, the major focus of this document is neurovascular imaging techniques. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Three-Dimensional Virtual Reality Simulation to Safe Planning Neurosurgical Procedure in Brain Aneurysms, Latin American Single-Center Experience: Advantages and Limitations

Background The neurosurgical approach to clipping cerebral aneurysms has been a complex challenge for all neurosurgeon experts in cerebrovascular surgery. The three-dimensional computed tomography angiography (3D-CTA) allows identifying bone and vascular structures close to an aneurysm to simulate in virtual 3D images, the appropriate and safest approach to cerebral aneurysm clipping.

Objectives This study aims to share our experience using 3D simulation as a support to the safe planning for cerebrovascular disease surgery.

Materials and Methods We reviewed the surgical outcomes from a cerebrovascular neurosurgeon using the 3D-CTA images in 360-degree reconstruction in the planning of the preoperative surgical procedure for the treatment of brain aneurysm. In all patients, the virtual surgical approach was replicated in real-time surgery.

Results We analyzed 34 patients around 51 ± 8 years of age. Of these, 76.5% (n = 26) and 23.5% (n = 8) were males and females, respectively. Saccular aneurysms were the most frequent (85%), the Arteries affected by aneurysms were middle cerebral artery (n = 6), basilar tip (n = 6), vertebral artery in V3 and V4 (n = 6), and posterior cerebral artery (n = 5). The virtual surgical pterional approach was the most frequently used (50%), followed by fronto-orbito-zigomático (29%) and far lateral (15%) approaches. There were no intraoperative complications in any patient.

Conclusion Preoperative 3D virtual reality simulation is a great support tool to perform a safe surgical procedure in real-time for the treatment of simple and complex brain aneurysms.

Digital Subtraction Angiography for CT Angiogram Negative Haemorrhages

BACKGROUND

In patients with subarachnoid haemorrhage (SAH) and a negative finding on CT angiography (CTA), further imaging with digital subtraction angiography (DSA) is commonly performed to identify the source of bleeding. The purpose of this study was to investigate whether negative findings on CTA can reliably exclude aneurysms in patients with acute SAH.

METHODS

This retrospective study identified all DSAs performed between August 2010 and July 2014 within our institution. CT angiography was performed with a 64-section multidetector row CT scanner. Only DSAs from patients with confirmed SAH and a negative CTA result were included in the final analyses. A fellowship-trained neuroradiologist reviewed the imaging results.

RESULTS

Of the 857 DSAs, 50 (5.83%) were performed in 35 patients with CTA-negative SAH. Of the 35 patients, three (8.57%) had positive findings on the DSA. In one patient, suspicious dissection of the extra- and intra-cranial segment of the right vertebral artery could not be confirmed even in retrospect. In the second patient, the suspicious finding of tiny protuberance from the left paraclinoid internal carotid artery (ICA) on DSA did not change on follow-up and did not change patient's management. The third patient had a posterior inferior cerebellar artery aneurysm, which was not seen on the initial CTA owing to the incomplete coverage of the head on the CTA.

CONCLUSION

In patients with SAH, negative findings on a technically sound CTA are reliable in ruling out aneurysms in any pattern of SAH or no blood on CT. Our observations need to be confirmed with larger prospective studies.

Contrast Enhancement of Aneurysm Sac Post-Pipeline Treatment Interpreted as Recanalization

Multiple imaging modalities are available to evaluate aneurysms post-flow diverter (FD) placement. Though digital subtraction angiography (DSA) is the gold standard imaging modality post-FD placement, it is not perfect, and neither are other techniques, including contrast-enhanced magnetic resonance angiography (CE-MRA) and magnetic resonance imaging (MRI). We present a case of a 73-year-old woman with a right internal carotid artery (ICA) aneurysm treated with a pipeline embolization device (PED). Initial follow-up post-PED placement by three-dimensional time-of-flight (3D-TOF) MRA demonstrated aneurysm occlusion, which was confirmed by computed tomography angiography (CTA) and CE-MRA in subsequent follow-up appointments. However, repeat CE-MRA two years later suggested recanalization of the aneurysm. After discussion with neuroradiologists and follow-up with a dynamic MRA, this finding was determined to be false. These findings shed light on the potential pitfall of using CE-MRA alone or any single imaging modality in the assessment of aneurysms post-PED placement. Our case report explores various imaging modalities used in the assessment of aneurysms post-PED placement and highlights the need to use multiple techniques for an accurate assessment.

Accuracy of 320-detector row nonsubtracted and subtracted volume CT angiography in evaluating small cerebral aneurysms

OBJECTIVE The study aimed to assess the diagnostic accuracy of 320-detector row nonsubtracted and subtracted volume CT angiography (VCTA) in detecting small cerebral aneurysms (< 3 mm) compared with 3D digital subtraction angiography (3D DSA). METHODS Six hundred sixty-two patients underwent 320-detector row VCTA and 3D DSA for suspected cerebral aneurysms. Five neuroradiologists independently reviewed VCTA and 3D DSA images. The 3D DSA was considered the reference standard, and the sensitivity, specificity, and accuracy of nonsubtracted and subtracted VCTA in depicting small aneurysms were analyzed. A p value < 0.05 was considered a significant difference. RESULTS According to 3D DSA images, 98 small cerebral aneurysms were identified in 90 of 662 patients. Nonsubtracted VCTA depicted 90 small aneurysms. Ten small aneurysms were missed, and 2 small aneurysms were misdiagnosed. The missed small aneurysms were located almost in the internal carotid artery, near bone tissue. The sensitivity, specificity, and accuracy of nonsubtracted VCTA in depicting small aneurysms were 89.8%, 99.2%, and 96.5%, respectively, on a per-aneurysm basis. Subtracted VCTA depicted 97 small aneurysms. Three small aneurysms were missed, and 2 small aneurysms were misdiagnosed. The sensitivity, specificity, and accuracy of subtracted VCTA in depicting small aneurysms were 96.9%, 99.2%, and 98.6%, respectively, on a per-aneurysm basis. There was no difference in accuracy between subtracted VCTA and 3D DSA (p = 1.000). However, nonsubtracted VCTA had significantly less sensitivity than 3D DSA and subtracted VCTA (p = 0.039 and 0.016, respectively). CONCLUSIONS Subtracted 320-detector row VCTA is sensitive enough to replace 3D DSA in the diagnosis of small cerebral aneurysms (< 3 mm). The accuracy rate of nonsubtracted VCTA was lower than that of subtracted VCTA and 3D DSA, especially in the assessment of small internal carotid artery aneurysms adjacent to the skull base.

Diagnosis and Treatment of Intracranial Aneurysms with 320-Detector Row Volumetric Computed Tomography Angiography

OBJECTIVES

The objective of the study was to determine the clinical utility of 320-detector row volume-computed tomographic angiography (VCTA) in the management of intracranial aneurysms.

METHODS

Between February 2011 and May 2015, 550 patients successfully underwent 320-detector row VCTA for suspected intracranial aneurysms. Three-dimensional (3D) digital subtraction angiography (DSA) was used as the ultimate reference standard, and the sensitivity, specificity, and accuracy of both nonsubtracted and subtracted VCTA in identifying aneurysms were analyzed.

RESULTS

Nonsubtracted VCTA identified 417 aneurysms (2 false-positive readings, 12 false-negative readings). The diagnostic sensitivity, specificity, and accuracy of non-subtracted VCTA, on a per-aneurysm basis, were 97.2%, 99.0%, and 97.6%, respectively. Subtracted VCTA identified 426 aneurysms (2 false-positive readings, 3 false-negative readings). The sensitivity, specificity, and accuracy of subtracted VCTA, on a per-aneurysm basis, were 99.3%, 99.0%, and 99.2%, respectively. No differences in diagnostic accuracy were found between subtracted VCTA and 3D DSA. Nonsubtracted VCTA, however, was observed to be significantly less sensitive than 3D DSA and subtracted VCTA. Twenty-six aneurysm cases were referred for surgical treatment based on VCTA imaging. All aneurysms were deemed completely occluded during surgical clipping. On the basis of VCTA imaging, 299 aneurysms were found suitable for endovascular coiling, of which 293 aneurysms (98%) were treated successfully.

CONCLUSIONS

The 320-detector row subtracted VCTA technique is an effective, first-line diagnostic imaging modality for surgical and endovascular treatment of aneurysms. The nonsubtracted VCTA was less accurate than the subtracted VCTA, especially for intracranial aneurysms adjoining bone tissue.

Aneurysmal subarachnoid haemorrhage from a neuroimaging perspective

Neuroimaging is a key element in the management of patients suffering from subarachnoid haemorrhage (SAH). In this article, we review the current literature to provide a summary of the existing neuroimaging methods available in clinical practice. Noncontrast computed tomography is highly sensitive in detecting subarachnoid blood, especially within 6 hours of haemorrhage. However, lumbar puncture should follow a negative noncontrast computed tomography scan in patients with symptoms suspicious of SAH. Computed tomography angiography is slowly replacing digital subtraction angiography as the first-line technique for the diagnosis and treatment planning of cerebral aneurysms, but digital subtraction angiography is still required in patients with diffuse SAH and negative initial computed tomography angiography. Delayed cerebral ischaemia is a common and serious complication after SAH. The modern concept of delayed cerebral ischaemia monitoring is shifting from modalities that measure vessel diameter to techniques focusing on brain perfusion. Lastly, evolving modalities applied to assess cerebral physiological, functional and cognitive sequelae after SAH, such as functional magnetic resonance imaging or positron emission tomography, are discussed. These new techniques may have the advantage over structural modalities due to their ability to assess brain physiology and function in real time. However, their use remains mainly experimental and the literature supporting their practice is still scarce.

The study of fetal-type posterior cerebral circulation on multislice CT angiography and its influence on cerebral ischemic strokes

PURPOSE

The purpose was to evaluate if patients with partial and full fetal-type posterior cerebral artery (PCA) could be more prone to lead to ischemic strokes on multislice computed tomographic angiography (MSCTA).

METHODS

A total of 202 patients who had undergone MSCTA examinations were divided into three groups: patients with full fetal-type posterior (FTP), patients with partial FTP, and patients without FTP. The odds ratio of having ischemic strokes was calculated.

RESULTS

The odds of having ischemic strokes in patients with full and partial FTP were 1.448 and 3.027, while P values were .391 and .0307, respectively.

CONCLUSION

Patients with a partial fetal-type PCA could be more prone to develop ischemic strokes.

Benefit of a Sharp Computed Tomography Angiography Reconstruction Kernel for Improved Characterization of Intracranial Aneurysms

BACKGROUND:

Computed tomography angiography (CTA) is the first-line imaging modality used for cerebral aneurysms because of its speed and sensitivity for detection, although digital subtraction angiography is often required for more detailed aneurysm shape delineation.

OBJECTIVE:

To determine whether a sharper CTA reconstruction kernel can better characterize an aneurysm and improve decision-making before intervention.

METHODS:

Fifteen patients presenting with aneurysmal subarachnoid hemorrhage underwent 64-row CTA. CTA data were reconstructed using the default H20f smooth kernel and a H60f sharp kernel and compared with contemporaneous catheter 3-dimensional rotational angiography (3DRA). Aneurysm neck, width, and aspect ratio measurements were made using intensity line plots of identical projections on all imaging datasets and compared by matched-pair statistics.

RESULTS:

Aneurysm neck measurements from the H20f smooth kernel revealed overestimation compared with both the sharp kernel (greater by 0.64 ± 0.21 mm, P &lt; .01) and 3DRA (greater by 0.68 ± 0.19 mm, P &lt; .01). There was no statistically significant difference between 3DRA and the sharp kernel CTA measurements. Neck measurements correlated well between the H60f kernel and 3DRA but not between the H20f Kernel and 3DRA (R 0.97 vs 0.86).

CONCLUSION:

H60f sharp CTA kernel reconstruction provides more accurate anatomic characterization of cerebral aneurysms than the H20f smooth kernel at the expense of less visually pleasing reconstructions. Because it does not require additional contrast, radiation, or imaging hardware and is more similar to 3DRA, it may aid in selecting the appropriate treatment strategy before to evaluation by catheter-based angiography.

Yield of catheter angiography after computed tomography negative, lumbar puncture positive subarachnoid hemorrhage [corrected]

BACKGROUND AND PURPOSE

Patients suspected of having aneurysmal subarachnoid hemorrhage (SAH) are initially evaluated with noncontrast head computed tomography. If the computed tomography is negative, but clinical concern for SAH is high, a lumbar puncture with cerebrospinal fluid analysis is typically performed. The purpose of this study was to evaluate the accuracy of cerebrospinal fluid xanthochromia and erythrocytosis for aneurysmal SAH.

METHODS

Medical records of all patients who underwent catheter angiography at Barnes Jewish Hospital between July 2002 and April 2012 for clinical suspicion of a ruptured brain aneurysm after a negative computed tomography scan and a lumbar puncture suspicious for SAH were reviewed. The cerebrospinal fluid analysis results, angiographic findings, and outcomes of each case were recorded.

RESULTS

Fifty-seven patients were identified. Two angiographic lesions were identified in patients with xanthochromia (2/24 patients, ie, 8.3%), both of which were confirmed to have ruptured. The diagnostic yield in patients with nonclearing erythrocytosis and no xanthochromia was 6.3% (1/16 patients), although this lesion was not considered the source of SAH.

CONCLUSIONS

Catheter angiography should be performed in patients with computed tomography negative but suspicious lumbar puncture, particularly in the presence of xanthochromia. The benefit of angiography in patients with erythrocytosis only is unclear and deserves future study.

Evaluating of small intracranial aneurysms by 64-detector CT Angiography: a comparison with 3-dimensional rotation DSA or surgical findings

BACKGROUND AND PURPOSE

The diagnostic performance of 64-detector computed tomographic angiography (CTA) for detection of small intracranial aneurysms (SIAs) was evaluated.

METHODS

In this prospective study, 112 consecutive patients underwent 64-detector CTA before volume-rendering rotation digital subtraction angiography (VR-RDSA) or surgery. VR-RDSA or intraoperative findings or both were used as the gold standards. The accuracy, sensitivity, specificity, and positive predictive values (PPV) and negative predictive values (NPV), as measures to detect or rule out SIAs, were determined by patient-based and aneurysm size-based evaluations.

RESULTS

The reference standard methods revealed 84 small aneurysms in 71 patients. The results of patient-based 64-detector CTA evaluation for SIAs were: accuracy, 98.2%; sensitivity, 98.6%; specificity, 97.6%; PPV, 98.6%; and NPV, 97.6%. The aneurysm-based evaluation results were: accuracy, 96.8%; sensitivity, 97.6%; specificity, 95.1%; PPV, 97.6%; and NPV, 95.1%. Two false-positive and two false-negative findings for aneurysms <3 mm in size occurred in the 64-detector CTA analysis.

CONCLUSION

The diagnostic performance of 64-detector CTA did not improve much compared with 16-detector CTA for detecting SIAs, especially for very small aneurysms. VR-RDSA is still necessary for patients with a history of subarachnoid hemorrhage if the CTA findings are negative.

Is this subarachnoid hemorrhage significant? A National Survey of Neurosurgeons

BACKGROUND

Previously all subarachnoid hemorrhage (SAH) patients were admitted, whereas now patients with angiography may be discharged.

OBJECTIVE

To survey neurosurgeons to determine current practice and what constitutes a clinically significant subarachnoid hemorrhage.

METHODS

We surveyed all neurosurgeons listed in the Canadian Medical Directory. We used a modified Dillman technique with up to five mailed surveys plus a pre-notification letter. Neurosurgeons rated the significance of 13 scenarios of subarachnoid hemorrhage. Scenarios varied from aneurysmal subarachnoid hemorrhage to patients with isolated xanthochromia in cerebrospinal fluid. Each scenario was rated for clinical significance using a 5-point scale [1(always) to 5(never)].

RESULTS

Of the 224 surveyed, 115 neurosurgeons responded. Scenarios with aneurysms requiring intervention, arteriovenous malformations, death or any surgical intervention all had median responses of 1 (IQR 1, 1). Scenarios having xanthochromia and few red blood cells in cerebrospinal fluid with negative computerized tomogram (CT) and angiography had median responses of 3 (IQR 1, 4). Scenarios with perimesencephalic pattern on CT with negative angiography had median of 3 (IQR 2, 4). Scenarios where patient is discharged from the emergency department had median of 4 (IQR 3, 5).

CONCLUSION

Subarachnoid hemorrhages due to aneurysms or arteriovenous malformations causing death or requiring surgical intervention are always clinically significant. Other types of nonaneurysmal subarachnoid hemorrhages had inconsistent ratings for clinical significance. These survey results highlight the need for further discussions to standardize the diagnosis of what constitutes a clinically significant subarachnoid hemorrhage and what care should be afforded to these patients.