Aneurysms of the posterior circulation: detection and treatment planning using volume-rendered three-dimensional helical computerized tomography angiography

Monitoring neurointerventional radiation doses using dose-tracking software: implications for the establishment of local diagnostic reference levels

OBJECTIVES

There is potential for high radiation exposure during neurointerventional procedures. Increasing regulatory requirements mandate dose monitoring of patients and staff, and justification of high levels of radiation exposure. This paper demonstrates the potential to use radiation dose-tracking software to establish local diagnostic reference levels.

METHODS

Consecutive neurointerventional procedures, performed in a single institution within a one-year period, were retrospectively studied. Dose area product (DAP) data were collected using dose-tracking software and clinical data obtained from a prospectively generated patient treatment database.

RESULTS

Two hundred and sixty-four procedures met the selection criteria. Median DAP was 100 Gy.cm² for aneurysm coiling procedures, 259 Gy.cm² for arteriovenous malformation (AVM) embolisation procedures, 87 Gy.cm² for stroke thrombolysis/thrombectomy, and 74 Gy.cm² for four-vessel angiography. One hundred and nine aneurysm coiling procedures were further studied. Six significant variables were assessed using stepwise regression analysis to determine effect on DAP. Aneurysm location (anterior vs posterior circulation) had the single biggest effect (p = 0.004).

CONCLUSIONS

This paper confirms variable radiation exposures during neurointerventional procedures. The 75th percentile (used to define diagnostic reference levels) of DAP measurements represents a reasonable guidance metric for monitoring purposes. Results indicate that aneurysm location has the greatest impact on dose during coiling procedures and that anterior and posterior circulation coiling procedures should have separate diagnostic reference levels.

KEY POINTS

• Dose-tracking software is useful for monitoring patient radiation dose during neurointerventional procedures • This paper provides a template for methodology applicable to any interventional suite • Local diagnostic reference levels were defined by using the 75th percentile of DAP as per International Commission on Radiological Protection recommendations • Aneurysm location is the biggest determinant of radiation dose during coiling procedures. • Anterior and posterior circulation coiling procedures should have separate diagnostic reference levels.

Anatomic Features of Paraclinoid Aneurysms: Computed Tomography Angiography Study of 144 Aneurysms in 136 Consecutive Patients

BACKGROUND

Paraclinoid aneurysms are among the most challenging aneurysms to treat. Computed tomography (CT) angiography helps in evaluating the radiological characteristics of these aneurysms next to bony structures.

OBJECTIVE

To present the CT angiography characteristics of paraclinoid aneurysms in order to better understand such pathology.

METHODS

The study examined CT angiography-based anatomical characteristics obtained retrospectively from 136 patients with 144 paraclinoid aneurysms selected from single-defined catchment populations in Finland. We examined the diameters of the parent artery (internal carotid artery), the location of the aneurysm, its dimensions (width, height, neck), and aneurysm wall irregularity.

RESULTS

We analyzed 144 paraclinoid aneurysms in 136 patients admitted to the hospital during 2000-2014. Multivariable analysis reveals that rupture aneurysms have the following radiological features: aneurysm larger than 5 mm in diameter (P = .006), irregular wall (P = .046), superior location, larger aspect ratio (P = .039), and neck wider than parent artery (P < .001).

CONCLUSION

Smaller diameter of the internal carotid artery and superior location, as well as a large and irregular aneurysm wall, are radiological characteristics of ruptured paraclinoid aneurysms, which CT angiography can measure easily.

Dual- versus Single-Energy CT-Angiography Imaging for Patients Undergoing Intracranial Aneurysm Repair

BACKGROUND

The invasiveness and risk of thromboembolic complications of catheter angiography underline the need for alternative imaging modalities in patients following intracranial aneurysm (IA) repair. However, the overall image quality of existing noninvasive imaging modalities, such as single-energy CT angiography (SE-CTA), compromises its value in this respect.

OBJECTIVE

We prospectively investigated the value of a novel dual-energy CTA (DE-CTA) scanner and algorithm for assessing the degree of occlusion and parent vessel patency in patients following IA repair.

METHODS

A prospective cohort of 17 patients underwent DE-CTA imaging following surgical or endovascular IA repair. This dataset was matched with an identical historical cohort of 17 patients, who underwent IA repair and SE-CTA imaging. Beam-hardening artifacts, as a measure for objective imaging quality were analyzed based on the volume of a prolate ellipsoid, whereas subjective imaging quality at the IA site and corresponding parent vessels was rated by 2 independent neuroradiologists on a scale from 4 (excellent, no artifacts) to 1 (poor, severe artifacts).

RESULTS

Objective DE-CTA image quality was markedly higher, compared to SE-CTA in patients undergoing surgical (0.77 ± 0.23 vs. 10.91 ± 1.88 mL, respectively; p < 0.001) or endovascular (32.36 ± 10.62 vs. 107.63 ± 24.51 mL, respectively; p = 0.026) IA repair. Subjective image quality for DE-CTA was significantly improved compared to SE-CTA in the surgical group but not in the endovascular group. The calculated dose values for DE-CTA in our study remain markedly below the legally required radiation dose limits.

CONCLUSION

The imaging quality of DE-CTA, especially for patients undergoing surgical IA repair, is distinctly superior, compared to SE-CTA imaging. Therefore, DE-CTA may serve as a noninvasive alternative for assessing the IA occlusion rate and parent vessel patency.

Use of Follow-Up Imaging in Isolated Perimesencephalic Subarachnoid Hemorrhage

Background and Purpose—

Multiple studies have shown that negative computed tomographic angiograms (CTAs) are reliable in excluding aneurysms in patients with isolated perimesencephalic subarachnoid hemorrhage (pSAH). We evaluate the use of digital subtraction angiography versus CTA for initial diagnosis and of angiographic follow-ups in patients with pSAH by performing an institutional analysis and a meta-analysis of literature.

Methods—

Retrospective institutional analysis of patients with pSAH was performed from 2008 to 2014. The number and types of follow-up imaging studies were tabulated. Initial and follow-up studies were evaluated by an experienced neuroradiologist for intracranial aneurysm. Meta-analysis of literature was performed to assess the use of initial digital subtraction angiography and of follow-up imaging.

Results—

Our institutional review revealed no additional use of initial digital subtraction angiography or of any angiographic follow-up after initial negative CTA in patients with pSAH on noncontrast CT. Meta-analysis of 40 studies yielded a total of 1031 patients. Only 8 aneurysms were first diagnosed on follow-ups (0.78%). Careful review showed that some of these aneurysms reported on follow-up are of questionable validity. Initial digital subtraction angiography and follow-up imaging after a negative initial CTA showed no statistically significant benefits.

Conclusions—

In patients meeting the strict imaging criteria of pSAH, initial negative CTA is reliable in excluding aneurysms. A critical review of the literature through meta-analysis shows no foundation for multiple follow-up studies in patients with pSAH.

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.

Cost-effectiveness of CTA, MRA and DSA in patients with non-traumatic subarachnoid haemorrhage

Objectives

Intra-arterial digital subtraction angiography (DSA), magnetic resonance angiography (MRA) and computed tomographic angiography (CTA) are imaging modalities used for diagnostic work-up of non-traumatic subarachnoid haemorrhage. The aim of our study was to compare the cost-effectiveness of MRA, DSA and CTA in the first year after the bleed.

Methods

A decision model was used to calculate costs and benefits (in quality-adjusted life-years [QALYs]) that accrued to cohorts of 1,000 patients. Costs and characteristics of diagnostic tests, therapy, patients’ quality of life and associated costs were respected. The diagnostic strategy with highest QALYs and lowest costs was considered most cost-effective.

Results

DSA was the most effective diagnostic option, yielding on average 0.6039 QALYs (95 % CI, 0.5761–0.6327) per patient, followed by CTA 0.5983 QALYs (95 % CI, 0.5704–0.6278) and MRA 0.5947 QALYs (95 % CI, 0.5674–0.6237). Cost was lowest for DSA (39,808 €; 95 % CI, 37,182–42,663), followed by CTA (40,748 €; 95 % CI, 37,937–43,831) and MRA (41,814 €; 95 % CI, 38,730–45,146). A strategy of CTA followed by DSA if CTA was negative or coiling deemed not feasible, was as effective as DSA alone at average costs of 39,767€ (95 % CI, 36,903–42,402).

Conclusion

A combined strategy of CTA and DSA was found to be the most cost-effective diagnostic approach.

Main Messages

• We defined a standard model for cost-effectiveness analysis in diagnostic imaging.

• Comparing total 1-year health costs and benefits, CTA is superior to MRA.

• A strategy of combining CTA and DSA was found to be the most cost-effective diagnostic approach.

Calcifications associated with pediatric intracranial arterial aneurysms: incidence and correlation with pathogenetic subtypes

BACKGROUND AND PURPOSE

Little is known about calcifications associated with pediatric intracranial arterial aneurysms (IAA). We sought to characterize calcifications associated with pediatric IAA according to aneurysm pathogenetic subtype.

MATERIALS AND METHODS

Patients with IAA less than 20 years of age were retrospectively identified. Three fellowship-trained neuroradiologists independently reviewed each patient's CT studies for calcifications of the parent artery or aneurysm. Aneurysmal calcification (ANC) was correlated with characteristics of the patient (age, sex) and aneurysm pathogenetic subtype, size, morphology, rupture status, and location.

RESULTS

Thirty-three patients (mean age 10 years) with 43 IAA were analyzed. There were no parent artery calcifications. Nine IAA were calcified. IAA in children with non-hemodynamic risk factors (arteriopathy, trauma, infection, tumor) were more commonly calcified than idiopathic IAA (p = 0.029). More than one third of the pediatric IAAs in this group (arteriopathy, infection trauma, tumor) were calcified. IAA ≥ 10 mm were more likely to be calcified (p = 0.03). IAA that were ruptured at presentation were less likely to be calcified (p = 0.03). ANC was not significantly associated with patient age (≤10 years vs. >10 years), sex, morphology (fusiform vs. saccular) or location (anterior vs. posterior circulation).

CONCLUSION

Aneurysmal but not parent artery calcifications are associated with a significant minority of pediatric IAA. Pediatric ANCs are associated with underlying non-hemodynamic vascular risk factors (arteriopathy, infection, trauma, and tumor), size ≥10 mm and non-hemorrhagic presentation.

State of the art in managing nontraumatic intracerebral hemorrhage

Nontraumatic intracerebral hemorrhage constitutes a major public health problem worldwide. Intracerebral hemorrhage leads to a high rate of morbidity and mortality. To date, no medical or surgical trials have clearly attested to the benefit of a particular therapy. The aim of this review was to summarize the best evidence for management decision-making in intracerebral hemorrhage.

Cerebrovascular biomodeling for aneurysm surgery: simulation-based training by means of rapid prototyping technologies

OBJECTIVE

Opportunities for developing procedural skills are progressively rare. Therefore, sophisticated educational tools are highly warranted.

METHODS

This study compared stereolithography and 3-dimensional printing for simulating cerebral aneurysm surgery. The latter jets multiple materials simultaneously and thus has the ability to print assemblies of multiple materials with different features. The authors created the solid skull and the cerebral vessels in different materials to simulate the real aneurysm when clipped.

RESULTS

Precise plastic replicas of complex anatomical data provide intuitive tactile views that can be scrutinized from any perspective. Hollowed out vessel sections allow serial clipping efforts, evaluation of different clips, and clip positions. The models can be used for accurate prediction of vascular anatomy, for optimization of teaching surgical skills, for advanced procedural competency training, and for patient counseling.

CONCLUSION

Simultaneous 3-dimensional printing is the most promising rapid prototyping technique to produce biomodels that meet the high demands of neurovascular surgery.

Applications of multislice CT angiography in the surgical clipping and endovascular coiling of intracranial aneurysms

Prompt diagnosis and therapy of aneurysms are critical for patients with nontraumatic subarachnoid hemorrhage (SAH). The aim of our study was to assess the clinical usefulness of multislice computed tomography angiography (CTA) in the surgical and endovascular treatment of intracranial aneurysms. A total of 195 cases with 206 intracranial aneurysms underwent CTA. Fifty (24%) aneurysms underwent surgical clipping while 156 (76%) aneurysms underwent endovascular coiling. In the five missed aneurysms at digital substraction angiography and the nine aneurysms with mass intracerebral hematomas, surgical treatment was successfully performed based on 16-slice CTA alone, and the other 36 aneurysms were clipped on the main basis of the CTA. The intraoperative findings correlated well with the CTA findings and all aneurysms were clipped successfully. Sixteen-slice CTA image information has been shown to determine the choice of aneurysm therapy and assist the surgical and endovascular treatment of intracranial aneurysms.

Application of multislice computed tomographic angiography in diagnosis and treatment of intracranial aneurysms

OBJECTIVES

The aim of the study is to assess the clinical value of 16-row multislice computed tomographic angiography (CTA) for detection and treatment of intracranial aneurysms.

PATIENTS AND METHODS

Between January 2005 and October 2008, 388 patients were included and successively underwent 16-slice CTA for suspected intracranial aneurysms. Three neuroradiologists independently reviewed CTA and DSA images. The combined interpretations of digital subtraction angiography (DSA) and surgical findings were considered as the ultimate reference standard against which the diagnostic accuracy of CTA and DSA were compared.

RESULTS

The reference standard revealed 287 aneurysms in 256 patients. There was no statistically significant difference in accuracy between 16-slice CTA and conventional DSA. The sensitivity, specificity, and accuracy of 16-slice CTA in detecting all aneurysms were 98.3, 97.0, and 97.9%, respectively, on a per-aneurysm basis. The sensitivity of 16-slice CTA was 90.0% for reader 1 and 93.3% for reader 2 for less than 3mm aneurysms. One hundred eighty-nine aneurysms were deemed amenable to endovascular therapy on the basis of CTA images, 98% of whom (185) were successfully treated with this method. Forty-eight aneurysms were considered candidates for surgical treatment, and all aneurysms were deemed completely occluded during surgical clipping. Sixteen-slice CTA images provided important preoperative information, which could assist the endovascular and surgical therapy of aneurysms.

CONCLUSIONS

Sixteen-slice CTA is a highly accurate imaging examination of the first line imaging technique for the detection of intracranial aneurysms, and it can provide sufficient diagnostic information in guiding the surgical and endovascular therapy of aneurysms.

Negative CT angiography findings in patients with spontaneous subarachnoid hemorrhage: When is digital subtraction angiography still needed?

BACKGROUND AND PURPOSE

CTA is becoming the frontline modality to reveal aneurysms in patients with SAH. However, in about 20% of SAH patients no aneurysm is found. In these cases, intra-arterial DSA is still performed. Our aim was to evaluate whether negative findings on CTA can reliably exclude aneurysms in patients with acute SAH.

MATERIALS AND METHODS

We conducted a retrospective analysis of all negative findings on CTAs performed from 2005 to 2009 in patients with spontaneous SAH. Findings were compared with DSA. CTAs were performed with a 64-section multidetector row CT scanner.

RESULTS

One hundred ninety-three patients with SAH and negative findings on CTA who underwent subsequent DSA were identified. The distribution of blood on unenhanced CT was the following: PMH in 93 patients, diffuse aneurysmal pattern in 50, no blood on CT (xanthochromic LP) in 32, and peripheral sulcal distribution in 18. All patients with PMH had negative findings on DSA. One patient with no blood on CT had vasculitis on DSA. Six of 18 (33%) patients with peripheral blood had vasculitis on DSA. Three of these were also diagnosed by CTA. All except 1 patient with diffuse aneurysmal blood had negative findings on DSA. One patient was diagnosed with an aneurysm on DSA (1/50, 0.5%). Repeat delayed DSA performed in 28 of these patients revealed a small aneurysm in 4 (14%). Five patients had a complication of DSA (2.6%); 1 was a clinical stroke (0.5%).

CONCLUSIONS

In patients with SAH, negative CTA findings are reliable in ruling out aneurysms in the PMH pattern or no blood on CT. DSA is indicated in the diffuse aneurysmal pattern of SAH, and repeat delayed DSA is required if the initial DSA findings are negative. When the blood is peripheral, CTA should be scrutinized for vasculitis and DSA is recommended for confirmation.

Sixteen-row multislice computed tomography angiography in the diagnosis and characterization of intracranial aneurysms: comparison with conventional angiography and intraoperative findings

Object

The goal of this study was to prospectively compare the effectiveness of 16-slice computed tomography (CT) angiography with that of conventional digital subtraction (DS) angiography and the surgical findings used to detect and characterize intracranial aneurysms.

Methods

Two hundred forty-four consecutive patients underwent both CT angiography and DS angiography no more than 3 days apart. Computed tomography angiography was performed with a 16-row multislice CT scanner in which a collimation of 0.75 mm was used. Two observers independently reviewed the CT images, and 1 of the 3 attending neuroradiologists reviewed the DS angiograms. They determined the presence, location, quantitation, and characterization of the intracranial aneurysms. Statistical results were calculated independently for the image interpretation performed by the 2 CT scan readers and the DS angiogram reader by using the combination of DS angiography or intraoperative findings or both as a reference standard.

Results

One hundred thirty-six patients harboring 153 intracranial aneurysms were included in this series. There was no statistically significant difference in sensitivity between 16-slice CT angiography and conventional DS angiography (p > 0.05). The sensitivities of 16-slice CT angiography for aneurysms < 5 mm, 5–10 mm, and > 10 mm were 94.8, 100, and 100%, respectively, on a per-aneurysm basis. The overall sensitivity and specificity of CT angiography for aneurysms were 98.0 and 99.1%, respectively. Sixteen-slice CT angiograms were clearer and more accurate in depicting the relationship of aneurysms to bone structures and adjacent branch vessels.

Conclusions

Computed tomography angiography using a 16-slice scanner is an accurate tool for detecting and characterizing intracranial aneurysms, including small aneurysms. Noninvasive 16-slice CT angiography will become a viable replacement for conventional DS angiography in the diagnosis and characterization of aneurysms.

Diagnostic accuracy of CT angiography with matched mask bone elimination for detection of intracranial aneurysms: comparison with digital subtraction angiography and 3D rotational angiography

BACKGROUND AND PURPOSE

Our aim was to determine the diagnostic accuracy of multisection CT angiography combined with matched mask bone elimination (CTA-MMBE) for detection of intracranial aneurysms compared with digital subtraction angiography (DSA) and 3D rotational angiography (3DRA).

MATERIALS AND METHODS

Between January 2004 and February 2006, 108 patients who presented with clinically suspected subarachnoid hemorrhage underwent both CTA-MMBE and DSA for diagnosis of an intracranial aneurysm. Two neuroradiologists, independently, evaluated 27 predefined vessel locations in the CTA-MMBE images for the presence of an aneurysm. After consensus, diagnostic accuracy of CTA was calculated per predefined location and per patient. Interobserver agreement was calculated with kappa statistics.

RESULTS

In 88 patients (81%), 117 aneurysms (82 ruptured, 35 unruptured) were present on DSA. CTA-MMBE detected all ruptured aneurysms except 1. Overall specificity, sensitivity, positive predictive value, and negative predictive value of CTA-MMBE were 0.99, 0.90, 0.98, and 0.95 per patient and 0.91, 1.00, 0.97, and 0.99 per location, respectively. Sensitivity was 0.99 for aneurysms >/=3 mm and 0.38 for aneurysms <3 mm. Interobserver agreement for aneurysm detection was excellent (kappa value of 0.92 per location and 0.80 per patient).

CONCLUSION

CTA-MMBE is accurate in detecting intracranial aneurysms in any projection without overprojecting bone. CTA-MMBE has limited sensitivity in detecting very small aneurysms. Our data suggest that DSA and 3DRA can be limited to the vessel harboring the ruptured aneurysm before endovascular treatment, after detection of a ruptured aneurysm with CTA.

Treatment decision in ruptured intracranial aneurysms: comparison between multi-detector row CT angiography and digital subtraction angiography

OBJECTIVE

The aim of this study was to determine the accuracy of multi-detector row computed tomography angiography (CTA) for the triage of patients with acutely ruptured aneurysms, and to assess how therapeutic decisions based on this method compared with digital subtraction angiography (DSA).

METHODS

Twenty-seven consecutive patients with acute subarachnoid hemorrhage were included, and underwent both CTA and DSA. CTA was performed on a 16-detector row CT scanner with a 0.75-mm collimation and a 0.558-beam pitch. Two readers reviewed the CTA data, and two different readers reviewed the DSA data. Aneurysm characteristics were recorded and treatment by surgical clipping or endovascular coil embolization was proposed.

RESULTS

A total of 24 aneurysms were identified on DSA in 21 patients. Sensitivity and specificity for CTA were 100% and 83%, respectively, on a per-aneurysm-basis. The correlation between DSA and CTA for the determination of sac and neck sizes was very good (r=0.92, and r=0.95, respectively, P<0.0001). Sensitivity and specificity for the detection of arterial branches incorporated into the aneurysmal sac or neck were 50% and 100%, respectively. In three aneurysms, readers judged CTA inappropriate for triage, because peri-aneurysmal branches were not properly visualized. Overall agreement between CTA and DSA regarding the therapeutic decision between surgical clipping and endovascular coil embolization in 24 aneurysms was good (kappa=0.76).

CONCLUSION

Multi-detector row CTA provides accurate anatomic information for aneurysm location as well as sac and neck sizes; however, the technique appears to have a low sensitivity in detecting branches incorporated into the aneurysmal sac.

Noninvasive imaging of treated cerebral aneurysms, Part II: CT angiographic follow-up of surgically clipped aneurysms

Although not useful for the evaluation of coiled aneurysms, CT angiography (CTA) is far superior to MR angiography (MRA) for the evaluation of aneurysms after surgical clipping. Using the latest multidetector row scanners and optimized imaging parameters, CTA can often effectively depict and follow small aneurysm remnants; demonstrate patency, stenosis, or vasospasm in the adjacent parent vessels; and provide surveillance of the entire cerebrovasculature for de novo aneurysms after surgical clipping. Despite these advances, conventional angiography remains the gold standard for the evaluation of surgically treated aneurysms and should be liberally used to resolve any cases of diagnostic uncertainty on noninvasive imaging.

Nouvelles techniques en imagerie vasculaire cervico-encéphalique et médullaire

Recent technical progress of MRI and CT made it possible to widen the field of exploration of the noninvasive vascular imaging in the study of supra-aortic, encephalic and medullary vessels. MRI of the carotid plaques, CT angiography in the detection of the intracranial aneurysms, intracranial time-resolved MRA and MRA of the spinal cord took their place in the field of the noninvasive vascular imaging.

Acute subarachnoid hemorrhage: using 64-slice multidetector CT angiography to “triage” patients’ treatment

INTRODUCTION

To evaluate the clinical role of CT angiography (CTA) in patients with acute subarachnoid hemorrhage (SAH) for treatment decision-making.

METHODS

Consecutive patients with acute SAH had CTA using a 64-slice scanner for initial clinical decision-making. Image processing included multiplanar volume reformatted (MPVR) maximum intensity projections (MIP) and 3D volume-rendered reconstructions. CTAs were used for (1) evaluating the cause of SAH, and (2) triaging aneurysm-bearing patients to the more appropriate management, either surgical clipping or endovascular coiling. CTA findings were confirmed by neurosurgical exploration or catheter angiography (digital subtraction angiography, DSA). Successful coiling provided evidence that triaging to endovascular treatment was correct.

RESULTS

Included in the study were 73 patients. CTA findings were confirmed by DSA or neurosurgical operation in 65 patients, and of these 65, 47 had aneurysmal SAH, 3 had vasculitis, 1 had arterial dissection and 14 had no underlying arterial abnormality. The cause of SAH was detected with CTA in 62 out of the 65 patients (95.4%, sensitivity 94%, specificity 100%). CTA revealed the aneurysm in 46 of 47 patients (98%, sensitivity 98%, specificity 100%, positive predictive value 100%, negative predictive value 82.3%), 1 of 3 vasculitides and 1 of 1 dissection. Of the 46 patients with aneurysm, 44 (95.7%) were referred for treatment based on CTA. In 2 patients (2 of 46, 4.4%) CTA was not informative enough to choose treatment requiring DSA. Of the 44 patients, 27 (61.4%) were referred to endovascular treatment and successful coiling was achieved in 25 (25 of 27, 92.6%).

CONCLUSION

CTA using a 64-slice scanner is an accurate tool for detecting and characterizing aneurysms in acute SAH. CTA is useful in the decision process whether to coil or clip an aneurysm.