Three-dimensional computerized tomography angiography—guided surgery of acutely ruptured cerebral anuerysms

Impact of Aneurysmal Subarachnoid Hemorrhage Severity on Contrast Media Arrival Time in Head Computed Tomography Angiography

Aim This study aims to evaluate the effect of subarachnoid hemorrhage (SAH) severity on contrast media (CM) arrival time in head computed tomography angiography (CTA) at SAH onset. Method A total of 67 patients who underwent head CTA were evaluated; 41 patients developed SAH (SAH group), and 26 patients had suspected unruptured cerebral aneurysms (non-SAH group). The patients of the SAH group were divided into mild (grades I-III), semi-severe (grade IV), and severe (grade V) groups according to Japanese guidelines. CM arrival time was measured for each case. Results The CM arrival time increased with SAH severity. The semi-severe and severe groups exhibited significantly longer CM arrival times compared to the non-SAH group (non-SAH: 11.1 ± 2.03, mild: 13.2 ± 2.97, semi-severe: 15.8 ± 3.45, severe: 16.6 ± 3.40). Conclusion The CM arrival time increases with SAH severity in head CTA at SAH onset. Therefore, it is important for operators to be aware of the possibility of slower-than-usual timing in severe cases of SAH.

The utility of dual-energy computed tomography angiography for the evaluation of brain aneurysms after endovascular coiling: a prospective study

BACKGROUND

Non-invasive alternatives to digital subtraction angiography (DSA) for follow-up of patients with coiled aneurysms are sought.

PURPOSE

To compare a novel method of dual-energy computed tomography angiography (DE-CTA) for postoperative assessment of coiled brain aneurysms to detect aneurysm recanalization and patency of adjacent blood vessels, with DSA.

MATERIAL AND METHODS

Patients who underwent endovascular cerebral aneurysm coiling were prospectively evaluated postoperatively by both DE-CTA and conventional DSA. CTA was performed using a novel dual-energy method with single-source and fast kilovoltage switching. DSA was performed using biplanar cerebral angiography. An experienced neuroradiologist and neurosurgeon, both blinded to the original radiological results, reviewed the images.

RESULTS

A total of 54 patients (16 men, 38 women; mean age=47.6 + 9 years) with 55 coiled aneurysms were enrolled in our study between July 2014 and June 2015: 29 patients had suffered a subarachnoid hemorrhage and 26 patients had an incidentally found cerebral aneurysm. All patients had at least one DSA and DE-CTA performed at most one week apart. DE-CTA showed a 100% sensitivity and specificity in detection of complete aneurysm occlusion and 80% sensitivity and specificity for detection of residual necks and domes. DE-CTA successfully detected all vascular diameter changes as comparable to DSA with minimal interfering artifact.

CONCLUSION

DE-CTA is a promising non-invasive alternative to conventional catheter-based angiography for identification of aneurysm recurrence and assessment of adjacent arteries after endovascular coiling. It allows for far more rapid image acquisition than DSA, is non-invasive, and is widely available at clinical centers.

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.

[Navigation in vascular neurosurgery]

Literature review is devoted to the role of frameless neuronavigation in surgery of distal aneurysms, cavernomas, arteriovenous malformations, Kimmerle's anomaly and revascularization surgeries. Visualization methods used in preoperative preparation of patients with vascular lesions compatible with frameless neuronavigation and the methods of intraoperative visualization as an addition to navigation are described.

A Multicenter Analysis of Computed Tomography Angiography Alone Versus Digital Subtraction Angiography for the Surgical Treatment of Poor-Grade Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Poor-grade aneurysmal subarachnoid hemorrhage (aSAH) is associated with increased intracranial pressure, and these patients are unstable with a high risk of rebleeding. Computed tomography angiography (CTA) has been proposed as an examination tool for the rapid detection of ruptured aneurysms. We aimed to determine the safety and efficacy of CTA alone for surgical treatment of poor-grade aSAH compared with digital subtraction angiography (DSA).

METHODS

We conducted a multicenter retrospective analysis of 144 patients with poor-grade aSAH who underwent surgical treatment for 2 different cohorts. Patients were grouped into CTA alone and DSA groups. Baseline characteristics, postoperative complications, and clinical outcomes at discharge and at last follow-up were compared between the 2 groups. Multivariate logistic regression models were used to assess the association between CTA alone and clinical outcomes after we adjusted for potential confounders.

RESULTS

Of the 116 patients included, 42 (36.2%) patents received CTA alone and 74 patients (63.7%), including 12 patients with CTA and DSA and 62 patients with DSA alone, received DSA before surgical treatment. Patients with larger ruptured aneurysms (P = 0.006), aneurysm sizes of larger than 5 mm (P = 0.025), presence of single aneurysms (P = 0.018), and presence of intraventricular hemorrhage (P = 0.019) more often received CTA alone. All ruptured aneurysms were clipped successfully during surgery. There were no statistically significant differences in postoperative complications and clinical outcomes between the 2 groups.

CONCLUSIONS

Although CTA alone can be safely and effectively used in most patients requiring surgical treatment, additional DSA may be considered in patients with smaller ruptured aneurysms or in those with multiple aneurysms.

Pattern of Cerebral Aneurysms in a Kenyan Population as Seen at an Urban Hospital

BACKGROUND

Intracranial aneurysms constitute a significant part of the caseload for any neurosurgical service. Despite the occurrence of intracranial aneurysms and the availability of advanced diagnostic tools and management options, there is a paucity of published data concerning aneurysm patterns in Kenya.

METHODS

This was a combined retrospective and prospective quantitative descriptive study. Following ethical approval, all patients with cerebral aneurysms seen on computed tomography angiography who presented at Nairobi Hospital between May 2010 and June 2014 were included. A standardized questionnaire was used to collect data on patient characteristics, indications for imaging, and radiologic findings. Analysis was carried out SPSS for Windows version 15.0.

RESULTS

The study included 121 patients with a female (71.9%) predominance; most (30.58%) of the patients were aged 50-59 years. There were 151 aneurysms observed, with 85.95% of patients having solitary aneurysms and 14.05% having multiple aneurysms; 82.1% of the aneurysms were located in the anterior circulation. Mean aneurysm size was 6.92 mm, mean neck diameter was 2.79 mm, and the range of diameter/neck ratio was 1-11.88 (mean 1.16). The rate of subarachnoid bleeding displayed an exponential increase with aneurysms 3 mm in size and appeared to plateau thereafter despite increasing aneurysm size. Most (78.8%) of the observed anterior communicating artery aneurysms were ruptured.

CONCLUSIONS

Most patients were postmenopausal women, who had a higher rate of aneurysms with an elevated risk of rupture for small aneurysms; this suggests that clinicians need to be more vigilant and have a higher index of suspicion in such patients with subtle clinical signs. This study revealed a pattern of aneurysms in accord with previous reports and is expected to serve as a basis for further research on aneurysm management, outcome, and prognostic indicators in the Kenyan population.

Effects of a high-pitch protocol and a hybrid iterative reconstruction algorithm on image quality of cerebral subtracted 3D CT angiography

PURPOSE

To evaluate the image quality and the radiation dose of 3D-computed tomography angiography (3D-CTA) with a high-pitch protocol and a hybrid iterative reconstruction (HIR).

MATERIALS AND METHODS

This was a prospective study and thirty patients were scanned at a 0.51-helical pitch with filtered back-projection (FBP, protocol-A), and 30 patients were scanned at a 0.91-helical pitch with FBP and HIR (protocol-B and C). The mean volume CT dose index (CTDI(vol)), image noise, and mean cerebral arterial and venous attenuation were compared between the three protocols. Two readers assessed image noise, arterial contrast and venous overlap.

RESULTS

The mean CTDI(vol) of protocol-B/C (38.9 mGy) was lower than that of protocol-A (49.7 mGy). Mean image noise of protocol-B [12.6 ± 1.3 Hounsfield units (HU)] was higher than that of protocol-A (10.3 ± 1.2 HU). There was no significant difference in arterial attenuation between protocol-A (327.5 ± 57.5 HU) and C (327.7 ± 59.4 HU). Venous attenuation of protocol-C (148.5 ± 50.4 HU) was lower than that of protocol-A (185.9 ± 50.6 HU). In qualitative analysis, the image noise of protocol-B was higher than that of protocol-A/C. Venous enhancement of protocol-B/C was more inconspicuous than that of protocol-A.

CONCLUSIONS

3D-CTA with a high-pitch protocol and HIR can reduce radiation dose while decreasing venous enhancement and image noise to an adequate level for diagnosis.

Usefulness of monochromatic imaging with metal artifact reduction software for computed tomography angiography after intracranial aneurysm coil embolization

BACKGROUND

Recently, a newly developed fast-kV switching dual energy CT scanner with a gemstone detector generates virtual high keV images as monochromatic imaging (MI). Each MI can be reconstructed by metal artifact reduction software (MARS) to reduce metal artifact.

PURPOSE

To evaluate the degree of metal artifacts reduction and vessel visualization around the platinum coils using dual energy CT with MARS.

MATERIAL AND METHODS

Dual energy CT was performed using a Discovery CT750 HD scanner (GE Healthcare, Milwaukee, WI, USA). In a phantom study, we measured the mean standard deviation within regions of interest around a 10-mm-diameter platinum coil mass on MI with and without MARS. Thirteen patients who underwent CTA after endovascular embolization for cerebral aneurysm with platinum coils were included in a clinical study. We visually assessed the arteries around the platinum coil mass on MI with and without MARS.

RESULTS

Each standard deviation near the coil mass on MI with MARS was significantly lower than that without MARS in a phantom study. On CTA of a clinical study, better visibility of neighboring arteries was obtained in 11 of 13 patients on MI with MARS compared to without MARS due to metal artifact reduction.

CONCLUSION

Dual energy CT with MARS reduces metal artifact of platinum coils, resulting in favorable vessel visualization around the coil mass on CTA after embolization.

Re-exploration of the craniotomy after surgical treatment of unruptured intracranial aneurysms

BACKGROUND

Unplanned re-exploration of the craniotomy after surgical treatment of unruptured intracranial aneurysms (UIAs) is sometimes required, but the underlying causes and rates of these procedures are seldom reported. This study retrospectively analyzed the causes of such re-explorations to identify methods for decreasing their necessity.

METHOD

From January 2000 to December 2011, 1,720 patients with a total of 1,938 UIAs underwent surgical treatment at our institution. From this cohort, 26 patients (1.5 %) with 38 UIAs required re-exploration. Clinical data, aneurysm characteristics, treatment methods, and the incidence and causes of re-exploration of the craniotomy were analyzed for these 26 patients.

RESULTS

Several causes of re-exploration were identified: compromised distal blood flow (eight patients, 0.47 %), hemorrhagic venous infarction (four patients, 0.23 %), brain retraction injury (three patients, 0.17 %), newly identified aneurysms (three patients, 0.17 %), bleeding from an incompletely clipped aneurysm (two patients, 0.12 %), epidural hematoma (two patients, 0.12 %), failed aneurysm clipping (two patients, 0.12 %) and other causes (two patients, 0.12 %). Annual re-exploration incidence rates ranged from 0 to 3.1 %. Annual incidence rates gradually decreased following the introduction of several intraoperative monitoring systems.

CONCLUSIONS

Precise surgical planning and careful operative techniques can reduce the incidence of unplanned re-exploration of the craniotomy. The introduction of various intraoperative monitoring systems can also contribute to a reduction in this incidence.

Clinical value of multi-slice 3-dimensional computed tomographic angiography in the preoperative assessment of meningioma

The aim of this study was to evaluate the clinical value of multislice 3-dimensional computed tomographic angiography (3D-CTA) in the preoperative assessment of meningiomas. A total of 331 cases with meningiomas confirmed by CT and MRI were examined using 3D-CTA. The locations of the tumors were observed to be as follows: parasagittal and falcine in 125 cases, sphenoidal in 39 cases, in the olfactory groove in 19 cases, tentorial in 21 cases, parasellar in 33 cases, petroclival in 29 cases, intraventricular in 7 cases and on the convexity of the brain in 58 cases. The reconstructed images were processed by shaded volume rendering, maximum intensity projection and color-shaded surface display. The 3D-CTA images were used to imitate the surgical approach. Surgery was performed according to the information provided in the 3D-CTA images. 3D-CTA provided clear 3D images of the meningioma and the relationship with the adjacent vessels and the skull base, and demonstrated the optimal surgical approach for removing the neoplasm. The results of 3D-CTA corresponded extremely well with the surgical observations. 3D-CTA is able to provide 3D images of the meningioma, adjacent vessels and the bones in the skull base. Furthermore, 3D-CTA supplies information vital in the selection of the optimal surgical approach and information that aids the management of the sinus during the surgery. 3D-CTA is of great value in the preoperative evaluation of meningiomas.

Comparing accuracy of cerebral aneurysm size measurements from three routine investigations: computed tomography, magnetic resonance imaging, and digital subtraction angiography

Modern imaging technologies, such as computed tomography (CT) angiography, magnetic resonance (MR) angiography, and digital subtraction (DS) angiography are widely used for pretreatment evaluation of cerebral aneurysms, but the relative accuracies of these modalities are unclear. This study compared the measurements of aneurysm neck and dome height and width on CT angiography, time-of-flight (TOF)-MR angiography, and DS angiography using a three-dimensional workstation. An elastic model of a side-wall aneurysm was connected to an artificial heart pulsatile circuit system. The aneurysm model was prepared using a silicone membrane of 0.6-mm thickness under normal physiological circulation parameters. Using this aneurysm model, three-dimensional TOF-MR angiography, contrast-enhanced CT angiography, and DS angiography were performed. Source images were post-processed on a dedicated workstation to calculate the aneurysm size. DS angiography measurements were found to be the most accurate. In contrast, aneurysm neck sizes measured on CT angiography were significantly wider than actual values (p < 0.05) and aneurysm heights measured using TOF-MR angiography were significantly lower than actual values (p < 0.01). In this in-vitro model, at least one aneurysm dimension measured with CT angiography and with TOF-MR angiography differed significantly from actual values. Aneurysm neck width markedly affects therapeutic planning, as a wide neck requires craniotomy or endovascular treatment using an adjunctive device, so inaccuracies should be considered when aneurysm treatment is planned using modern methods of visualization.

Nontraumatic subarachnoid hemorrhage management: evaluation with reduced iodine volume at CT angiography

PURPOSE

To evaluate the technical quality and the diagnostic performance of a protocol with use of low volumes of contrast medium (25 mL) at 64-detector spiral computed tomography (CT) in the diagnosis and management of adult, nontraumatic subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

This study was performed outside the United States and was approved by the institutional review board. Intracranial CT angiography was performed in 73 consecutive patients with nontraumatic SAH diagnosed at nonenhanced CT. Image quality was evaluated by two observers using two criteria: degree of arterial enhancement and venous contamination. The two independent readers evaluated diagnostic performance (lesion detection and correct therapeutic decision-making process) by using rotational angiographic findings as the standard of reference. Sensitivity, specificity, and positive and negative predictive values were calculated for patients who underwent CT angiography and three-dimensional rotational angiography. The intraclass correlation coefficient was calculated to assess interobserver concordance concerning aneurysm measurements and therapeutic management.

RESULTS

All aneurysms were detected, either ruptured or unruptured. Arterial opacification was excellent in 62 cases (85%), and venous contamination was absent or minor in 61 cases (84%). In 95% of cases, CT angiographic findings allowed optimal therapeutic management. The intraclass correlation coefficient ranged between 0.93 and 0.95, indicating excellent interobserver agreement.

CONCLUSION

With only 25 mL of iodinated contrast medium focused on the arterial phase, 64-detector CT angiography allowed satisfactory diagnostic and therapeutic management of nontraumatic SAH.

Bilateral middle cerebral artery aneurysms: a comparative study of unilateral and bilateral approaches

The best surgical method for the treatment of patients with bilateral middle cerebral artery (bMCA) aneurysms has not been fully determined yet. The main purpose of this study is to compare the surgical results of unilateral and bilateral approaches to bMCA aneurysms including mean operation time, mean hospital stay, and mean cost, in the experience of the same neurosurgical team. Between January 2001 and June 2010, 22 patients with bMCA aneurysms were surgically treated in our institution. In 12 cases (54.5 %), ipsilateral and contralateral MCA aneurysms were successfully clipped via unilateral approach. In the remaining 10 cases, bilateral approach was necessary because of some technical difficulties. Although the surgical results were almost the same, mean operation time and mean hospital stay were, respectively, 46 and 37 % shorter and mean cost per person was 23 % lower for the patients in the unilateral group. In addition, the severity of brain edema, total length of the contralateral (A1+M1) segment, and the configuration of contralateral aneurysm were found to be the determinant parameters affecting the feasibility of the unilateral approach. To our knowledge, this is the first study in the literature that compares the clinical outcomes of unilateral and bilateral approaches to bMCA aneurysms. The results of surgery for both approaches are almost the same. However, the unilateral approach has certain advantages compared to the bilateral approach. Therefore, the unilateral approach may be a good alternative in surgical management of patients with bMCA aneurysms in selected cases and the abovementioned parameters can help the neurosurgeon in patient selection.

Angiographic CT with intravenous contrast injection compared with conventional rotational angiography in the diagnostic work-up of cerebral aneurysms

BACKGROUND AND PURPOSE

Noninvasive imaging of cerebral aneurysms is still considered inferior to conventional angiography. The purpose of this study was to evaluate the diagnostic accuracy of ivACT in the assessment of intracranial aneurysms compared with 3D-DSA.

MATERIALS AND METHODS

We included 13 patients with 15 incidental unruptured saccular aneurysms scheduled for diagnostic angiographic work-up in our study. In each patient, we performed an ivACT and a conventional angiography including a 3D rotational run. During postprocessing, MPR images were generated for each technique. Maximal aneurysm diameter, neck diameter, aneurysm height, maximum width, bulge height, parent artery diameter, and angle between the parent artery and aneurysm apex were measured for each aneurysm.

RESULTS

3D-DSA and ivACT both provided images of high quality without artificial disturbances (ie, motion artifacts). Measurements of all parameters resulted in comparable values for both modalities with a strong correlation (P ≤ .001).

CONCLUSIONS

ivACT is feasible for the noninvasive visualization of saccular cerebral aneurysms and may provide reliable diagnostic information for the assessment of aneurysm size and geometry comparable with conventional intra-arterial 3D rotational angiography. These preliminary results might be a first promising step to replacing conventional angiography in preinterventional aneurysm imaging.

Noninvasive imaging techniques in the diagnosis and management of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating condition, requiring prompt diagnosis and therapeutic intervention as well as close monitoring for the development of complications including vasospasm (VS). Although digital subtraction angiography is still considered the gold standard for the diagnosis of aSAH (and vasospasm), new and less invasive modalities are emerging including ultrasound, CT, CT angiography and CT perfusion, and MR imaging. The current evidence for the use of these newer modalities is described for the diagnosis of aSAH and the management of its sequelae including VS.

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.

Separate demonstration of arterial- and venous-phase by 3D-CT angiography for brain tumors using 64-multidetector row CT: 3D-CT arteriography and 3D-CT venography

We assessed the usefulness of the separate demonstration of the arterial- and venous phase on 3D-CT angiography (3D-CTA) using a 64-multidetector row CT (MDCT) scanner for the surgery of brain tumors. Nineteen patients with meningiomas (n=11), schwannomas, metastatic brain tumors (n=2 each), glioblastoma multiforme, malignant lymphoma, craniopharyngioma, and embryonal carcinoma (n=1 each) underwent scanning on a 64-MDCT scanner. After dynamic CT scanning to determine the scan timing for the arterial- and venous-phase, we individually scanned the arterial- and venous phase for 4 sec after injecting a nonionic contrast medium. Using the CT threshold setting and subtraction and cutting techniques, we produced individual 3D-CT images of the arteries, veins, tumors, and bones. The operators subjectively assessed the usefulness of these images in comparison with 3D-CTA. We separately demonstrated the arterial- and venous phase on 3D-CTA covering the entire head in all 19 cases. The 3D-CT arteriographs, 3D-CT venographs, and the fused 3D-CT images facilitated our understanding of the 3D anatomic relationship among the tumor, arteries, veins, and bony structures. In 14 of 19 cases our method provided the surgically valuable findings; the information on the anatomical relation between tumor and the surrounding arteries and veins (in 13 cases) the identification of anatomical course of the encased vessels (in one), and feeding arteries and draining veins (in one), and discrimination between the venous sinus and tumor (in one). The anatomical information yielded by our technique makes safer surgery possible. If more detailed information which 3D-CTA cannot provide is required, our method should be performed.

Advanced imaging applications for endovascular procedures

Advanced imaging techniques, particularly in CT and MRI, have become state-of-the-art to support the performance of interventional neuroradiologic procedures. Multidetector CT scanners with submillimeter detectors and real-time workstations have allowed the use of a noninvasive study, CT angiography, as a first-line diagnostic study at many institutions to detect and evaluate the morphology of aneurysms. Follow-up for postsubarachnoid spasm now includes transcranial Doppler, CT angiography, and sometimes perfusion to guide therapy. While both intracranial and extracranial stenosis have long been well evaluated by MR and CT angiography, information about the intimal wall and plaque morphology is now possible. In the setting of acute ischemia, CT with perfusion or MR with diffusion and perfusion has increased the ability to separate territory at risk from infarcted tissue, and can help to guide more appropriate intervention. This article addresses current state-of the-art imaging applications as well as a few techniques on the horizon that show great promise in helping to characterize those lesions amenable to endovascular therapy.

Usefulness of preoperative three-dimensional computed tomographic angiography with two-dimensional computed tomographic imaging for rupture point detection of middle cerebral artery aneurysms

OBJECTIVE

We report the technique of three-dimensional computed tomographic (CT) angiography with a two-dimensional CT image aiding in the early operation of ruptured middle cerebral artery aneurysms. This combined image allows the prediction of the rupture point in the aneurysm and may reduce the risk of rupture during early clipping surgery.

METHODS

The findings for 14 patients with 14 middle cerebral artery ruptured aneurysms who underwent subsequent early clipping were analyzed. The average aneurysm size was 8.5 mm, and there were two large and one giant aneurysms. CT examinations were performed by means of a multidetector CT scanner (Aquilion M16; Toshiba Medical Systems, Tokyo, Japan) and reconstructed with a workstation (ZIO M900 QUADRA; Amin Co., Ltd., Tokyo, Japan). We constructed an operating view through three-dimensional CT angiography for a lateral transsylvian approach with a two-dimensional CT image (nonshaded volume-rendering image), which was perpendicular to the direction of the surgical approach. Using this combined image, we predicted the rupture point of the aneurysm and successfully performed clipping surgery through a lateral transsylvian approach. Rupture points were confirmed at the time of surgery. Rupture points of 13 out of 14 aneurysms appeared as we expected, but one differed; all aneurysms were successfully clipped. Thirteen of the 14 patients could be clipped without rupture at surgery, but the remaining patient experienced rupture just after craniotomy.

CONCLUSION

The combination of three-dimensional CT angiography and two-dimensional CT images may help improve the surgical outcome by indicating aneurysmal rupture points, leading to the prevention of rupture.

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.

Surgical planning for retrosigmoid craniotomies improved by 3D computed tomography venography

OBJECTIVE

It is impossible to precisely anticipate the crooked course of the transverse and sigmoid sinuses and their individual relationship to superficial landmarks such as the asterion during retrosigmoid approaches. This study was designed to evaluate this anatomical relationship with the help of a surgical planning system and to analyze the impact of these in vivo findings on trepanation placement in retrosigmoid craniotomies.

METHODS

In a consecutive series of 123 patients with pathologies located in the cerebellopontine angle, 72 patients underwent surgical planning for retrosigmoid craniotomies based on 3D volumetric renderings of computed tomography venography. By opacity modulation of surfaces in 3D images the position of the asterion was assessed in relationship to the transverse-sigmoid sinus transition (TST) and compared to its intraoperative localization. We evaluated the impact of this additional information on trepanation placement.

RESULTS

The spatial relationship of the asterion and the underlying TST complex could be identified and recorded in 66 out of 72 cases. In the remaining 6 cases the sutures were ossified and not visible in the 3D CT reconstructions. The asterion was located on top of the TST in 51 cases, above the TST in 4 cases, and below the TST in 11 cases. The location of the trepanation was modified in 27 cases due to the preoperative imaging findings with major and minor modifications in 10 and 17 cases, respectively.

CONCLUSION

Volume-rendered images provide reliable 3D visualization of complex and hidden anatomical structures in the posterior fossa and thereby increase the precision in retrosigmoid approaches.

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.

Computed Tomographic Angiography as the Primary Diagnostic Study in Spontaneous Subarachnoid Hemorrhage

PURPOSE

To evaluate the utility of computed tomographic angiography (CTA) as the primary diagnostic investigation in patients with spontaneous subarachnoid hemorrhage (SAH), and to correlate the results with intraoperative findings in those with ruptured aneurysms.

MATERIALS AND METHODS

A retrospective review of 243 patients with spontaneous SAH was performed. The patients selected were those with acute SAH confirmed by noncontrast head computed tomography or by cerebrospinal fluid findings from a lumbar puncture. Patients subsequently underwent preoperative three-dimensional CTA as the sole or primary diagnostic study. The results of the CTA were correlated with the intraoperative findings in those patients undergoing emergent surgical clipping of acutely ruptured intracranial aneurysms.

RESULTS

CTA correctly detected the ruptured aneurysm in 170 of the 171 cases, which required surgical clipping. Our data demonstrates that CTA has a 99.4% detection rate in acutely ruptured aneurysms as compared to intraoperative findings [confidence interval 97.8-99.9%].

CONCLUSION

CTA can provide prompt and accurate diagnostic and anatomic information in the setting of SAH with an excellent detection rate in acute ruptured aneurysms. These findings suggest an increased role for CTA in the evaluation of cerebral aneurysms.

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.

Multislice CT angiography in the selection of patients with ruptured intracranial aneurysms suitable for clipping or coiling

Introduction

We sought to establish whether CT angiography (CTA) can be applied to the planning and performance of clipping or coiling in ruptured intracranial aneurysms without recourse to intraarterial digital subtraction angiography (IA-DSA).

Methods

Over the period April 2003 to January 2006 in all patients presenting with a subarachnoid haemorrhage CTA was performed primarily. If CTA demonstrated an aneurysm, coiling or clipping was undertaken. IA-DSA was limited to patients with negative or inconclusive CTA findings. We compared CTA images with findings at surgery or coiling in patients with positive CTA findings and in patients with negative and inconclusive findings in whom IA-DSA had been performed.

Results

In this study, 224 consecutive patients (mean age 52.7 years, 135 women) were included. In 133 patients (59%) CTA demonstrated an aneurysm, and CTA was followed directly by neurosurgical (n = 55) or endovascular treatment (n = 78). In 31 patients (14%) CTA findings were categorized as inconclusive, and in 60 (27%) CTA findings were negative. One patient received surgical treatment on the basis of false-positive CTA findings. In 17 patients in whom CTA findings were inconclusive, IA-DSA provided further diagnostic information required for correct patient selection for any therapy. Five ruptured aneurysms in patients with a nonperimesencephalic SAH were negative on CTA, and four of these were also false-negative on IA-DSA. On a patient basis the positive predictive value, negative predictive value, sensitivity, specificity and accuracy of CTA for symptomatic aneurysms were 99%, 90%, 96%, 98% and 96%, respectively.

Conclusion

CTA should be used as the first diagnostic modality in the selection of patients for surgical or endovascular treatment of ruptured intracranial aneurysms. If CTA renders inconclusive results, IA-DSA should be performed. With negative CTA results the complementary value of IA-DSA is marginal. IA-DSA is not needed in patients with negative CTA and classic perimesencephalic SAH. Repeat IA-DSA or CTA should still be performed in patients with a nonperimesencephalic SAH.

CRANIOTOMY AND CLIPPING OF INTRACRANIAL ANEURYSM IN A STEREOSCOPIC VIRTUAL REALITY ENVIRONMENT

OBJECTIVE

The release of results of International Subarachnoid Aneurysm Trial in 2003 caused a shift in the paradigm of management of ruptured intracranial aneurysms. The cases selected for microsurgical clipping nowadays are usually those patients with aneurysms that are not suitable for embolization, and are often complex and difficult. We devised an innovative application of operative planning and training for craniotomy and microsurgical clipping of intracranial aneurysms in a stereoscopic virtual reality environment.

METHODS

Patient-specific Digital Imaging and Communications in Medicine data from computed tomographic angiography of the intracranial circulation and cranium were transferred to the workstation (Dextroscope; Volume Interactions Pte. Ltd., Singapore, Singapore). An aneurysm clip database was loaded into the patient data set. Three-dimensional volume rendering was followed by data coregistration and fusion.

RESULTS

Virtual head positioning and craniotomy were carried out to simulate the microscopic visualization. Clip selection could be carried out with reference to the angle of application. This allows one to see the exposure and degree of obliteration of an aneurysm with the various angles of approach.

CONCLUSION

The virtual craniotomy and microsurgical clipping application simulated the operative environment. Its role in neurosurgical training is encouraging and should be further developed.

Pitfalls in the preoperative evaluation of subarachnoid hemorrhage without digital subtraction angiography: report on 2 cases

BACKGROUND

Digital subtraction angiography has been used in the diagnosis of aneurysmal SAH and as a preoperative imaging method. However, new methods such as MRA and CTA are now deemed by many institutions to provide sufficient information to allow surgery to go ahead without a preliminary DSA scan. We report on 2 cases of SAH in which there were additional lesions that were difficult to evaluate because of the lack of DSA information.

CASE DESCRIPTIONS

The fist patient demonstrated SAH with IVH. Computed tomographic angiography revealed an ACoA aneurysm with a bleb. We first thought that the SAH and IVH were both caused by a ruptured ACoA aneurysm but noted that hemorrhage pattern was inconsistent with the location and orientation of the aneurysm. A DSA scan revealed a dural arteriovenous fistula in the region of the craniocervical junction, supplied by the right occipital artery. We surmised that the SAH and IVH were caused by a large varix of DAVF and that the ACoA aneurysm would be unruptured. The second patient presented with a 1-week history of headaches and nausea and was diagnosed to have an SAH caused by a ruptured MCA aneurysm. We suspected vasospasm in the second portion of the MCA on CTA, but could not precisely evaluate the affected lesions. A diffusion-weighted MRI scan 4 days after surgery revealed a high-intensity area in the region of the right MCA. The MCA had already seemed to be affected at admission because vasospasm rarely develops within 4 days of the onset of SAH.

CONCLUSIONS

As long as the CTA scan is of adequate quality and shows the aneurysm clearly, we consider that an additional DSA provides little useful information for surgery. However, in such cases, the information from a DSA scan is needed for the evaluation of secondary factors that are not directly associated with the aneurysm.

High-concentration contrast media (HCCM) in CT angiography of the carotid system: impact on therapeutic decision making

BACKGROUND

CT angiography (CTA) is a minimally invasive technique that enables precise delineation of extracranial and intracranial vascular anatomy and pathology based on high intravascular density. With a 64-slice MDCT scanner, improved first-pass vascular visualization can be obtained with HCCM (400 mg I/ml) using 25 ml for combined intra-and extracranial studies and 20 ml for intracranial examinations alone. We reviewed 23 patients with extra-cranial stenoocclusive disease and 12 patients with intra-cranial aneurysms. Two additional patients presented with a mycotic aneurysm and a micro arteriovenous malformation (micro-AVM).

RESULTS

In 23 patients with 27 significant (> or =70%) vascular stenoses, high intraluminal contrast density and optimal projection of the stenosis profile facilitated precise delineation of the residual lumen in all vessels affected. Pseudoocclusion was present in 3 of the 27 vessels (11%) and ulceration in 5 (18.5%). CTA, in contrast to digital subtraction angiography (DSA) and magnetic resonance angiography (MRA), was able to delineate the mural constituents of stenoses, particularly marked calcification (present in 17 of 27 vessels, 62.9%). Eccentric vessel wall narrowing indicated dissection in three vessels (11%) and circular postradiation fibrosis was found in two vessels (7.4%). High-quality CTA obviated the need for DSA for diagnostic purposes in every patient. The decision regarding surgical treatment in nine vessels (33%) was influenced by the location of the stenosis relative to the carotid bifurcation, the length of the stenosis, and the level of the carotid bifurcation. Endovascular treatment in 12 vessels (44.4%) and the appropriate choice and placement of endovascular devices was affected by the anatomic configuration of the supraaortic vessels, and by the intrastenotic dimensions relative to the dimensions of the vessel proximal and distal to the stenosis. The anatomic availability of collaterals, relevant for both treatments, was determined via the anterior communicating artery (ACoA) in 91.3% of patients and the posterior communicating artery (PCoA) in 80.4% of patients. Intracranial CTA displayed the lesion location, configuration, size, and orientation in each of the 12 patients with intracranial aneurysms and in the two patients with a micro-AVM and a mycotic aneurysm. The correct diagnosis was established prior to DSA in each patient. Following CTA, the role of DSA was relegated to endovascular therapy in three aneurysms. For surgical candidates, DSA served to exclude potential multiplicity in ten saccular aneurysms and in one mycotic aneurysm. CTA provided information supplementary to DSA in 11 of the 13 aneurysms (84.6%). Delineation of blebs, calcification, thrombus, or incorporation of branches facilitated risk stratification with respect to rupture and to surgical or endovascular treatment.

CONCLUSION

Advantages of CTA, such as virtual independence from the hemodynamic situation, delineation of landmarks and vessel wall calcification, and the ability to quantify vessels and aneurysms, distinguish this technique from other noninvasive vascular imaging techniques and DSA. Acquired with the use of iodinated HCCM, CT angiograms permit excellent recognition of appropriate diagnostic and interventional treatment paths, thereby facilitating improved decision-making regarding endovascular or surgical treatment.

Rebleeding from ruptured intracranial aneurysms in North Eastern Province of Japan. A cooperative study

OBJECT

Rebleeding from ruptured intracranial aneurysms is a major cause of death and disability. With regard to the factors that precipitate the rebleeding and influence the time course after initial bleeding, previous reports differ in their results, and the number of patients investigated was not sufficient for valid conclusions. This study was thus designed to clarify the factors related to rebleeding from ruptured intracranial aneurysms in a large group of patients of the North Eastern Province of Japan.

METHODS

We found 181 patients with rebleeding after hospitalization among 5612 cases of ruptured intracranial aneurysms from January 1997 to December 2001 in 33 major hospitals in the North Eastern Province of Japan. We analyzed the data with respect to the time course after bleeding and rebleeding, the arterial blood pressure, the situation when rebleeding occurred, the methods of neuroimaging, the level of consciousness, the treatment and the outcome.

RESULTS

Of 181 patients who were hospitalized, rebleeding occurred in 65 (35.9%) within 3 h and 88 (48.6%) within 6 h after the initial subarachnoid hemorrhage (SAH). The consciousness level before the rebleeding varied widely in distribution, but belonged to the drowsiness or less [Japan coma scale (JCS) single-digit] in 83 patients (45.8%), but after rebleeding, JCS triple-digits (semicoma to coma) included 152 patients (84.0%). Systolic arterial blood pressure prior to rebleeding was most commonly between 120 and 140 mmHg. Rebleeding did occur more frequently during angiography (totally 29 patients, 20%) and much less frequently during 3D-CTA and MRA procedures (a single case). Treatment consisted of aneurysm neck clipping in 72 patients (40.0%), endovascular therapy with coils in 4 patients (2.2%) and conservative ones in 103 patients (56.9%). As to outcome, 109 patients with rebleeding (60.2%) died in 3 months following initial SAH.

CONCLUSION

Rebleeding occurs more frequently in the earlier period after the initial SAH than previously believed. Thus, more aggressive pharmacologically induced systemic arterial hypotension appears to be important for preventing rebleeding but ultimate outcome of more aggressive hypotension is yet to be determined. If feasible, in order to avoid catheter-angiography related rebleeding, evaluations solely with 3D-CTA and MRA should be in consideration and earlier surgical intervention seems essential as rebleeding does occur often within the first 3 h of onset.

CT angiography "spot sign" predicts hematoma expansion in acute intracerebral hemorrhage

BACKGROUND AND PURPOSE

Morbidity and mortality in spontaneous intracerebral hemorrhage (ICH) are correlated with hematoma progression. We hypothesized that the presence of tiny, enhancing foci ("spot sign") within acute hematomas is associated with hematoma expansion.

METHODS

We prospectively studied 39 consecutive patients with spontaneous ICH by computed tomography angiography within 3 hours of symptom onset. Scans were reviewed by 3 readers. Patients were dichotomized according to the presence or absence of the spot sign. Clinical and radiological outcomes were compared between groups. The predictive value of this sign was assessed in a multivariate analysis.

RESULTS

Thirteen patients (33%) demonstrated 31 enhancing foci. Baseline clinical variables were similar in both groups. Hematoma expansion occurred in 11 patients (28%) on follow-up. Seventy-seven percent of patients with and 4% without hematoma expansion demonstrated the spot sign (P<0.0001). Sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio for expansion were 91%, 89%, 77%, 96%, and 8.5, respectively. Interobserver agreement was high (kappa=0.92 to 0.94). In patients with the spot sign, mean volume change was greater (P=0.008), extravasation more common (P=0.0005), and median hospital stay longer (P=0.04), and fewer patients achieved a good outcome (modified Rankin Scale score <2), although the latter was not significant (P=0.16). No differences in hydrocephalus (P=1.00), surgical intervention (P=1.00), or death (P=0.60) were noted between groups. In multiple regression, the spot sign independently predicted hematoma expansion (P=0.0003).

CONCLUSIONS

The computed tomography angiography spot sign is associated with the presence and extent of hematoma progression. Fewer patients achieve a good clinical outcome and hospital stay was longer. Further studies are warranted to validate the ability of this sign to predict clinical outcomes.