Volume-rendered helical computerized tomography angiography in the detection and characterization of intracranial aneurysms

OBJECT: The goal of this study was to evaluate the utility of volume-rendered helical computerized tomography (CT) angiography in patients with intracranial aneurysms. The authors compared the abilities of CT angiography, digital subtraction (DS) angiography, and three-dimensional time-of-flight magnetic resonance (MR) angiography to characterize aneurysms. METHODS: Helical CT angiography was performed in 45 patients with suspected intracranial aneurysms by using volume-rendered multiplanar reformatted (MPR) images. Digital subtraction angiography was performed using biplane angiography. These studies and those performed using MR angiography were interpreted in a blinded manner. Two neurosurgeons and two interventional neuroradiologists independently graded the utility of CT angiography with respect to aneurysm characterization. Fifty-five aneurysms were detected. Of these, 48 were evaluated for treatment. Computerized tomography angiography was judged to be superior to both DS and MR angiography in the evaluation of the arterial branching pattern at the aneurysm neck (compared with DS angiography, p = 0.001, and with MR angiography, p = 0.007), aneurysm neck geometry (compared with DS angiography, p = 0.001, and with MR angiography, p = 0.001), arterial branch incorporation (compared with DS angiography, p = 0.021, and with MR angiography, p = 0.001), mural thrombus (compared with DS angiography, p < 0.001), and mural calcification (compared with DS angiography, p < 0.001, and with MR angiography, p < 0.001). For surgical cases, CT angiography had a significant impact on treatment path (p = 0.001), operative approach (p = 0.001), and preoperative clip selection (p < 0.001). For endovascular cases, CT angiography had an impact on treatment path (p < 0.02), DS angiography study time (p = 0.01), contrast agent usage (p = 0.01), and coil selection (p = 0.02). Computerized tomography angiography provided unique information about 39 (81%) of 48 aneurysms, especially when compared with DS angiography (p = 0.003). The sensitivity and specificity of CT angiography compared with DS angiography was 1. The sensitivity and specificity of CT and DS angiography studies compared with operative findings were 0.98 and 1, respectively. CONCLUSIONS: Computerized tomography angiography is equal to DS angiography in the detection and superior to DS angiography and MR angiography in the characterization of brain aneurysms. Information contained in volume-rendered CT angiography images had a significant impact on case management.     

Three-dimensional helical computerized tomography angiography in the diagnosis,characterization, and management of middle cerebral artery aneurysms: comparison with conventional angiography and intraoperative findings

OBJECT: Middle cerebral artery (MCA) aneurysms can be difficult to detect and characterize. The authors describe the utility and impact of helical computerized tomography (CT) angiography for the evaluation of aneurysms in this location, and compare this modality with digital subtraction (DS) angiography and intraoperative findings. METHODS: Two hundred fifty-one patients with suspected cerebral aneurysms underwent CT angiography. Two-dimensional multiplanar reformatted images and three-dimensional CT angiograms were examined by two independent readers in a blinded fashion. Results were compared with findings on DS angiograms to determine the relative efficacy of these modalities in the detection and characterization of aneurysms. Questionnaires completed by neurosurgeons and endovascular therapists were used to determine the impact of CT angiograms on aneurysm management. Twenty-eight patients harboring 31 MCA aneurysms and 26 patients without aneurysms were identified using CT angiography. The sensitivity of CT angiography and DS angiography for MCA aneurysms was 97%; both techniques showed 100% specificity. In 76% of evaluations, the CT angiography studies provided information not available on DS angiography examinations. For the characterization of aneurysms, CT angiography was rated superior (72%) or equal (20%) to DS angiography in 92% of cases evaluated (p < 0.001). Computerized tomography angiography was evaluated as the only study needed for patient triage in 82% of cases (p < 0.001), and as the only study needed for treatment planning in 89% of surgically treated (p < 0.001) and in 63% of endovascularly treated cases (p < 0.001). The information acquired on CT angiograms changed the initial treatment plan in 24 (67%) of these 36 complex lesions (p < 0.01). The aneurysm appearance intraoperatively was identical or nearly identical to that seen on CT angiograms in 17 (89%) of 19 of the surgically treated cases. CONCLUSIONS: Computerized tomography angiography has unique advantages over DS angiography and is a viable alternative to the latter modality in the diagnosis, triage, and treatment planning in patients with MCA aneurysms.     

Limitations of three-dimensional reconstructed computerized tomography angiography after clip placement for intracranial aneurysms

OBJECT: The authors compared the usefulness of three-dimensional (3D) reconstructed computerized tomography (CT) angiography with 3D digital subtraction (DS) angiography in assessing intracranial aneurysms after clip placement. A retrospective review of clinical cases was performed. METHODS: Between May 2001 and May 2003, 17 patients with a total of 20 intracranial aneurysms underwent 3D CT and 3D DS angiography following clip placement. The authors assessed the presence or absence of residual aneurysm necks and stenoocclusive changes in the parent artery and the neighboring artery. The efficacy of CT angiographic visualization was also evaluated. In 12 of the 20 aneurysms, both 3D modalities similarly demonstrated the residual aneurysm neck and stenoocclusive changes in the parent artery and neighboring artery. Three-dimensional CT angiography failed to demonstrate three of the aneurysms, and the studies were not considered suitable for evaluation because of the presence of metallic artifacts. In the remaining five studies, the 3D CT angiograms did not effectively demonstrate the neighboring and parent arteries. The detectability of residual aneurysm necks was correlated with the clip material and with the number of clips applied. CONCLUSIONS: Three-dimensional DS angiography is still necessary in cases involving multiple clips or with cobalt alloy clips because the clips appear as metal artifacts on 3D CT angiography.     

Comparison of multislice computerized tomography angiography and digital subtraction angiography in the postoperative evaluation of patients with clipped aneurysms

OBJECT: In this study the accuracy of multislice computerized tomography (MSCT) angiography in the postoperative examination of clip-occluded intracranial aneurysms was compared with that of intraarterial digital subtraction (DS) angiography METHODS: Forty-nine consecutive patients with 60 clipped aneurysms (41 of which had ruptured) were studied with the aid of postoperative MSCT and DS angiography. Both types of radiological studies were reviewed independently by two observers to assess the quality of the images, the artifacts left by the clips, the completeness of aneurysm occlusion, the patency of the parent vessel, and the duration and cost of the examination. The quality of MSCT angiography was good in 42 patients (86%). Poor-quality MSCT angiograms (14%) were a result of the late acquisition of images in three patients and the presence of clip or motion artifacts in four. Occlusion of the aneurysm on good-quality MSCT angiograms was confirmed in all but two patients in whom a small (2-mm) remnant was confirmed on DS angiograms. In one patient, occlusion of a parent vessel was seen on DS angiograms but missed on MSCT angiograms. The sensitivity and specificity for detecting neck remnants on MSCT angiography were both 100%, and the sensitivity and specificity for evaluating vessel patency were 80 and 100%, respectively (95% confidence interval 29.2-100%). Interobserver agreements were 0.765 and 0.86, respectively. The mean duration of the examination was 13 minutes for MSCT angiography and 75 minutes for DS angiography (p < 0.05). Multislice CT angiography was highly cost effective (p < 0.01). CONCLUSIONS: Current-generation MSCT angiography is an accurate noninvasive tool used for assessment of clipped aneurysms in the anterior circulation. Its high sensitivity and low cost warrant its use for postoperative routine control examinations following clip placement on an aneurysm. Digital subtraction angiography must be performed if the interpretation of MSCT angiograms is doubtful or if the aneurysm is located in the posterior circulation.     

Ruptured aneurysm arising from the proximal end of an azygos anterior cerebral artery--case report

A 59-year-old woman presented with subarachnoid hemorrhage. Conventional angiography and three-dimensional computed tomography (3-D CT) angiography showed a saccular aneurysm at the junction of the azygos anterior cerebral artery (ACA) and the left A1 segment. This aneurysm was associated with a fenestration of the right hypoplastic A1 segment. The aneurysm neck was completely clipped, preserving the azygos ACA and other perforators. Aneurysm of the azygos ACA is almost always located at the distal bifurcation, and rarely at the proximal end. Proximal azygos ACA aneurysm can mimic anterior communicating artery aneurysm. Therefore, accurate preoperative diagnosis is critical using 3-D CT angiography as well as conventional angiography, and close follow up of patient is necessary to monitor for development of a de novo aneurysm at the distal bifurcation of the azygos ACA.     

Simulation of clipping position for cerebral aneurysms using three-dimensional computed tomography angiography

A novel method for the simulation of the clipping position for cerebral aneurysms based on three-dimensional computed tomography (3D CT) angiography was evaluated. Rotating the regional 3D CT angiography images including the aneurysm provided the virtual intraoperative views of 36 cerebral aneurysms that were eligible for clipping through a pterional approach with a perpendicularly applied straight clip. The cut-along-trace function of the 3D CT workstation was used to simulate the clipping position. The presence or absence of aneurysm remnants was preoperatively evaluated by observing the clipping simulation image. Intraoperative endoscopy and postoperative cerebral angiography were routinely performed to confirm the completeness of obliterations. Nineteen of 21 aneurysms for which complete obliteration was preoperatively expected were confirmed to have no aneurysm remnant. Nine of 15 aneurysms which were expected to have aneurysm remnant were confirmed to persist. The clipping simulation images could correctly predict aneurysm remnant after the initial clipping with a sensitivity of 90.5% and specificity of 60%. The present simulation method can predict aneurysm remnants and improve the likelihood of complete obliteration by clipping.     

Surgical anatomy of the cerebral arteries in patients with subarachnoid hemorrhage: comparison of computerized tomography angiography and digital subtraction angiography.

OBJECT: The purpose of this study was to compare computerized tomography (CT) angiography and digital subtraction (DS) angiography studies in patients with subarachnoid hemorrhage (SAH) to assess their vascular anatomy relevant to cerebral aneurysm surgery. METHODS: From a prospective series of 100 patients with SAH, the authors selected 73 patients whose CT angiography studies were of adequate quality and in whom DS angiography of both carotid arteries had been performed. Eleven patients with no DS angiographic studies of the vertebrobasilar artery were only evaluated for the anterior half of the circle of Willis. Anterior communicating arteries (ACoAs), both precommunicating anterior cerebral arteries (A1 segments), both posterior communicating arteries (PCoAs), and both precommunicating posterior cerebral arteries (P1 segments) were assessed on CT angiography and DS angiography by two independent observers. CONCLUSIONS: Computerized tomography angiography compares well with DS angiography for visualizing normal-sized arteries, and is superior for visualizing ACoAs and hypoplastic A1 and P, segments. Important preoperative aspects such as dominant A1 segments and PCoAs are equally well seen using either modality. Neither method enabled the authors to visualize more than 50% of PCoAs. Use of CT angiography can provide the required preoperative anatomical information for aneurysm surgery in most patients with SAH.     

Abdominal Aortic Aneurysm Measurements for Endovascular Repair: Intra- and Interobserver Variability of CT Measurements

OBJECTIVES: to evaluate the intra- and interobserver variability in measurements of the aorta and iliac arteries in patients with abdominal aortic aneurysms (AAAs) considered for endovascular repair using computed tomography angiography (CTA). METHODS: the diameter of the neck, aneurysm, right and left iliac artery were measured by 5 observers in 10 consecutive patients. Measurements were performed on hard copy using a ruler and on a workstation using an electronic caliper. RESULTS: the intraobserver variability showed a decrease going from hard copy to workstation in the standard deviation of the differences of the paired observations for the neck from 3.54 mm to 1.18 mm; for the aorta from 4.16 to 1.72 mm; for the right iliac from 1.87 to 1.01 mm; for the left iliac from 2.07 to 0.87 mm. The interobserver variability showed a similar decrease for the neck in all ten pairs of observers; for the aorta in two, for the right iliac and left iliac in five. However, the difference between observers regularly exceeded 2 mm. CONCLUSION: the use of a workstation and electronic calipers results in lower intra- and interobserver variability. However, the results still show a clinically relevant difference between the observers. Therefore, it is necessary to develop an automatic observer-independent measurement technique.     

Assessment of brain aneurysms by using high-resolution magnetic resonance angiography after endovascular coil delivery

OBJECT: Digital subtraction (DS) angiography is the current gold standard of assessing intracranial aneurysms after coil placement. Magnetic resonance (MR) angiography offers a noninvasive, low-risk alternative, but its accuracy in delineating coil-treated aneurysms remains uncertain. The objective of this study, therefore, is to compare a high-resolution MR angiography protocol relative to DS angiography for the evaluation of coil-treated aneurysms. METHODS: In 2003, the authors initiated a prospective protocol of following up patients with coil-treated brain aneurysms using both 1.5-tesla gadolinium-enhanced MR angiography and biplanar DS angiography. Using acquired images, the subject aneurysm was independently scored for degree of remnant identified (complete obliteration, residual neck, or residual aneurysm) and the surgeon's ability to visualize the parent vessel (excellent, fair, or poor). RESULTS: Thirty-seven patients with 42 coil-treated aneurysms were enrolled for a total of 44 paired MR angiography-DS angiography tests (median 9 days between tests). An excellent correlation was found between DS and MR angiography for assessing any residual aneurysm, but not for visualizing the parent vessel (K = 0.86 for residual aneurysm and 0.10 for parent vessel visualization). Paramagnetic artifact from the coil mass was minimal, and in some cases MR angiography identified contrast permeation into the coil mass not revealed by DS angiography. An intravascular microstent typically impeded proper visualization of the parent vessel on MR angiography. CONCLUSIONS: Magnetic resonance angiography is a noninvasive and safe means of follow-up review for patients with coil-treated brain aneurysms. Compared with DS angiography, MR angiography accurately delineates residual aneurysm necks and parent vessel patency (in the absence of a stent), and offers superior visualization of contrast filling within the coil mass. Use of MR angiography may obviate the need for routine diagnostic DS angiography in select patients.     

Intraaneurysmal flow dynamics study featuring an acrylic aneurysm model manufactured using a computerized tomography angiogram as a mold.

OBJECT: To obtain precise flow profiles in patients' aneurysms, the authors developed a new in vitro study method featuring an aneurysm model manufactured using three-dimensional computerized tomography (3D CT) angiography. METHODS: A clear acrylic basilar artery (BA) tip aneurysm model manufactured from a patient's 3D CT angiogram was used to analyze flow modifications during one cardiac cycle. Stereolithography was utilized to create the aneurysm model. Three-dimensional flow profiles within the aneurysm model were obtained from velocity measurements by using laser Doppler velocimetry. The aneurysm inflow/outflow zones changed dynamically in their location, size of their cross-sectional area, and also in their shapes over one cardiac cycle. The flow velocity at the inflow zone was 16.8 to 81.9% of the highest axial velocity in the BA with a pulsatility index (PI) of 1.1. The flow velocity at the outflow zone was 16.8 to 34.3% of the highest axial velocity of the BA, with a PI of 0.68. The shear stress along the walls of the aneurysm was calculated from the fluid velocity measured at a distance of 0.5 mm from the wall. The highest value of shear stress was observed at the bleb of the aneurysm. CONCLUSIONS: This clear acrylic model of a BA tip aneurysm manufactured using a CT angiogram allowed qualitative and quantitative analysis of its flow during a cardiac cycle. Accumulated knowledge from this type of study may reveal pertinent information about aneurysmal flow dynamics that will help practitioners understand the relationship among anatomy, flow dynamics, and the natural history of aneurysms.     

Morphology Parameters for Mirror Posterior Communicating Artery Aneurysm Rupture Risk Assessment

Recent studies have shown that posterior communicating artery (PComA) aneurysms are more likely to rupture. However, surgical intervention for PComA aneurysms may be associated with increased treatment-related morbidity rate. Therefore, it is meaningful to investigate the factors related to PComA aneurysm rupture. The purpose of this study was to identify morphological parameters that significantly correlate with PComA aneurysm rupture. We divided 14 pairs of mirror posterior communicating artery aneurysms (PComA-MANs) into ruptured and unruptured groups. Computed tomography angiography (CTA) imaging was evaluated with three-dimensional (3D) Slicer to generate models of the aneurysms and surrounding vasculature. Nine morphological parameters [size, height, width, neck width, aspect ratio (AR), bottleneck factor (BNF), height/width ratio (H/W), size ratio (SR), and bleb formation] were examined in the two groups for significance with respect to rupture. By contrast, statistically significant differences were found in ruptured and unruptured group for size, AR, BNF, SR, and bleb formation (P < 0.05). Parameters that had no significant differences between the two groups were height (P = 0.103), width (P = 0.078), neck width (P = 0.808), and H/W (P = 0.417). We conclude that MANs may be a useful model for the morphological analysis of intracranial aneurysm rupture. Larger size, higher AR, BNF, SR, and bleb formation may be related to rupture of PComA aneurysms. Larger sample studies minimizing the interference from patient-related factors and aneurysm type were expected for acquiring more accurate assessment of the relationship between these parameters and PComA aneurysm rupture.     

Predicting aneurysm rupture probabilities through the application of a computed tomography angiography-derived binary logistic regression model

OBJECT:The goal of this study was to establish a biomathematical model to accurately predict the probability of aneurysm rupture. Biomathematical models incorporate various physical and dynamic phenomena that provide insight into why certain aneurysms grow or rupture. Prior studies have demonstrated that regression models may determine which parameters of an aneurysm contribute to rupture. In this study, the authors derived a modified binary logistic regression model and then validated it in a distinct cohort of patients to assess the model's stability. METHODS:Patients were examined with CT angiography. Three-dimensional reconstructions were generated and aneurysm height, width, and neck size were obtained in 2 orthogonal planes. Forward stepwise binary logistic regression was performed and then applied to a prospective cohort of 49 aneurysms in 37 patients (not included in the original derivation of the equation) to determine the log-odds of rupture for this aneurysm. RESULTS:A total of 279 aneurysms (156 ruptured and 123 unruptured) were observed in 217 patients. Four of 6 linear dimensions and the aspect ratio were significantly larger (each with p < 0.01) in ruptured aneurysms than unruptured aneurysms. Calculated volume and aneurysm location were correlated with rupture risk. Binary logistic regression applied to an independent prospective cohort demonstrated the model's stability, showing 83% sensitivity and 80% accuracy. CONCLUSIONS:This binary logistic regression model of aneurysm rupture identified the status of an aneurysm with good accuracy. The use of this technique and its validation suggests that biomorphometric data and their relationships may be valuable in determining the status of an aneurysm.     

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

OBJECT: The aim of this study was to determine whether computerized tomography (CT) angiography could be used to identify and characterize aneurysms of the posterior circulation and guide optimal treatment selection, and how data obtained using this method compared with intraoperative findings. METHODS: Patients suspected of harboring brain aneurysms underwent CT angiography and digital subtraction (DS) angiography; the results were prospectively interpreted by blinded independent evaluators. All patients with posterior circulation aneurysms were consecutively enrolled in the study. After treatment, neurosurgeons and endovascular therapists evaluated the ability of CT and DS angiography to demonstrate features of the lesions important for triage between treatment options (Wilcoxon signed-rank test) and to allow for coil or clip preselection and complete treatment planning (McNemar test of proportions), while using intraoperative findings as the basis of truth. In 242 patients overall, CT angiography detected 38 aneurysms and two aneurysmal blisters in 32 patients. The sensitivity of CT angiography in revealing posterior circulation aneurysms was 100% compared with DS angiography, with no false-positive results. Furthermore, CT angiography was sufficient as the sole study at triage for 65% of the posterior circulation aneurysms (26 of 40 lesions; p < 0.001), including 62% of the complex lesions (p < 0.001), and permitted coil or clip preselection in 74% of treated cases (20 of 27 cases; p < 0.002). Results of CT angiography revealed information about mural calcification and intraluminal thrombus not available on DS angiography, which affected patient care. CONCLUSIONS: In this study population, CT angiography was comparable to DS angiography in the detection and characterization of aneurysms of the posterior circulation. Computerized tomography angiography was used successfully to triage patients between endovascular and neurosurgical treatment options in a significant proportion of cases and permitted treatment planning in more than 70% of treated cases.     

Computerized tomography angiography in patients with subarachnoid hemorrhage: from aneurysm detection to treatment without conventional angiography.

OBJECT: The purpose of this study was to determine prospectively whether and to what extent computerized tomography (CT) angiography can serve as the sole imaging method for a preoperative workup in patients with ruptured intracranial aneurysms. METHODS: During a 1-year period, all patients who presented to the authors' hospital with subarachnoid hemorrhage demonstrated by unenhanced CT scanning or lumbar puncture underwent CT angiography. Two radiologists evaluated the CT angiography source images and maximum intensity projection slabs and arrived at a consensus. They categorized the quality of the CT angiography as adequate or inadequate and classified aneurysms that were detected as definitely or possibly present. The parent artery of anterior communicating artery aneurysms was identified by asymmetrical anterior cerebral artery size and asymmetrical aneurysm location. The parent artery was indicated by the larger A1 segment in cases of asymmetrical A1 size. Only CT angiograms of adequate quality that revealed aneurysms classified as definitely present and with an unequivocal parent artery were presented to the neurosurgeons, who decided whether preoperative digital subtraction (DS) angiography should still be performed. Forty-nine of the 100 studied patients did not undergo surgery because of poor clinical condition, nonaneurysmal cause of the hemorrhage, or endovascular treatment of the ruptured aneurysm. Of the 51 patients who underwent surgery, radiologists required DS angiography in 17 patients; the imaging technique provided greater certainty in 13 instances. The neurosurgeons required DS angiography 11 times; this provided additional information in two instances. Twenty-three (45%) of the 51 patients were surgically treated successfully on the basis of CT angiography findings alone. CONCLUSIONS: Computerized tomography angiography can replace DS angiography as the preoperative neuroimaging technique in a substantial proportion of patients with ruptured intracranial aneurysms.     

Comparison of Scientific Calipers and Computer-Enabled CT Review for the Measurement of Skull Base and Craniomaxillofacial Dimensions

Traditionally, cadaveric studies and plain-film cephalometrics provided information about craniomaxillofacial proportions and measurements; however, advances in computer technology now permit software-based review of computed tomography (CT)-based models. Distances between standardized anatomic points were measured on five dried human skulls with standard scientific calipers (Geneva Gauge, Albany, NY) and through computer workstation (StealthStation 2.6.4, Medtronic Surgical Navigation Technology, Louisville, CO) review of corresponding CT scans. Differences in measurements between the caliper and CT model were not statistically significant for each parameter. Measurements obtained by computer workstation CT review of the cranial skull base are an accurate representation of actual bony anatomy. Such information has important implications for surgical planning and clinical research.     

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.     

Use of spiral computerized tomography angiography in patients with subarachnoid hemorrhage in whom subtraction angiography did not reveal cerebral aneurysms

OBJECT: Patients with subarachnoid hemorrhage (SAH) in whom angiography does not demonstrate diagnostic findings sometimes suffer recurrent disease and actually harbor undetected cerebral aneurysms. The management strategy for such cases remains controversial, but technological advances in spiral computerized tomography (CT) angiography are changing the picture. The purpose of this prospective study was to examine how spiral CT angiography can contribute to the detection of cerebral aneurysms that cannot be visualized on angiography. METHODS: In 134 consecutive patients with SAH, a prospective search for the source of bleeding was performed using digital subtraction (DS) and spiral CT angiography. In 21 patients in whom initial DS angiography yielded no diagnostic findings, spiral CT angiography was performed within 3 days. Patients in whom CT angiography provided no diagnostic results underwent second and third DS angiography sessions after approximately 2 weeks and 6 months, respectively. Six patients with perimesencephalic SAH were included in the 21 cases. Six of the other 15 patients had small cerebral aneurysms detectable by spiral CT angiography, five involving the anterior communicating artery and one the middle cerebral artery. Two patients in whom initial angiograms did not demonstrate diagnostic findings proved to have a ruptured dissecting aneurysm of the vertebral artery; in one case this was revealed at autopsy and in the other during the second DS angiography session. A third DS angiography session revealed no diagnostic results in 13 patients. CONCLUSIONS: Spiral CT angiography was useful in the detection of cerebral aneurysms in patients with SAH in whom angiography revealed no diagnostic findings. Anterior communicating artery aneurysms are generally well hidden in these types of SAH cases. A repeated angiography session was warranted in patients with nonperimesencephalic SAH and in whom initial angiography revealed no diagnostic findings, although a third session was thought to be superfluous.     

Microsurgical management of cerebral aneurysms based in CT angiography with three-dimensional reconstruction (3D-CTA) and without preoperative cerebral angiography

Summary  Objective. To study the posibilities of the microsurgical management of ruptured intracranial aneurysms with the sole preoperative information provided by computed tomography angiography with three-dimensional reconstruction (3D-CTA).  Methods. Patients were studied with 3D-CTA after diagnosis of subarachnoid hemorrhage. If the study had an adequate quality and revealed an aneurysm congruent with the clinical findings or neurological examination and/or with the location of the bleeding on computed tomography (CT) scan an early microsurgical clipping of the lesion was done. When the quality of the 3D-CTA study was not adequate or the quality being adequate displayed no lesions or the findings were not accurate enough to warrant direct microsurgical treatment, the patient was studied with cerebral digital substraction (DS) angiography. A total of 44 consecutive patients harbouring a total of 47 intracranial aneurysms diagnosed by 3D-CTA and without preoperative DS angiography were submitted to microsurgical clipping and included in the study.  Results. The overall mortality was 15.9% and the favourable results evaluated 6 months after discharge by means of the Glasgow Outcome Scale reached 70.4%. All lesions were successfully clipped. Surgery was done a mean of 4.1 days after the admission bleeding. A total of four microlesions undiagnosed by 3D-CTA were found at surgery and clipped. Postoperative DS angiography and necropsy findings were also used as control of the 3D-CTA findings but no additional information was provided excepting the finding in DS angiography of an asymptomatic intracavernous aneurysm. Therefore the sensitivity of the 3D-CTA for diagnosis of symtomatic aneurysms was 100% and the overall sensitivity 90.4%.  Conclusions. We have reached similar results in patients operated on with or without preoperative angiography. 3D-CTA provides very valuable anatomical information, which has an additional value in the microsurgical treatment of aneurysms of the anterior communicating artery complex. Finally, selected cases of ruptured intracranial aneurysms can be successfully managed with the preoperative information provided by 3D-CTA and without DS angiography.     

Angiographically occult, progressively expanding, giant vertebral artery aneurysm. Case report

Hunterian ligation is a well-known treatment for complex aneurysms not amenable to direct microsurgical clip application. After proximal parent vessel occlusion, cerebral angiography is typically used to confirm aneurysm thrombosis. The authors report on a vertebral artery (VA) aneurysm that had progressively expanded and caused brainstem compression after hunterian ligation, despite nondiagnostic findings on both conventional and computed tomography (CT) angiography at multiple time points. This 64-year-old woman underwent hunterian ligation of a 1.8-cm VA aneurysm at the origin of the right posterior inferior cerebellar artery. An immediately postoperative conventional angiogram and follow-up CT angiograms obtained 5 and 6 years postligation confirmed complete obliteration of the lesion. Nine years after the initial surgery, however, the patient experienced neurological deterioration. Although CTs showed substantial aneurysm enlargement together with pontine compression, angiograms once again demonstrated complete right VA occlusion with no retrograde filling of the aneurysm. On reexploration, the aneurysm was effectively debulked, clipped, and obliterated. Arterial bleeding was found in the lesion neck, as was evidence of microrecanalization. Hunterian ligation for complex aneurysms carries the risk of microrecanalization and lesion expansion despite nondiagnostic angiography. Although this ligation procedure remains a viable treatment option in carefully selected patients, an extended follow-up evaluation period may be required even when imaging suggests aneurysm obliteration.     

Prospective evaluation of surgical microscope-integrated intraoperative near-infrared indocyanine green videoangiography during aneurysm surgery

OBJECT: The authors prospectively compared a new technique of surgical microscope-based indocyanine green (ICG) videoangiography with intraoperative or postoperative digital subtraction (DS) angiography. METHOD: The technique was performed during 187 surgical procedures in which 124 aneurysms in 114 patients were clipped. Using a newly developed setup, the ICG technique has been integrated into an operating microscope (Carl Zeiss Co., Oberkochen, Germany). A microscope-integrated light source containing infrared excitation light illuminates the operating field. The dye is injected intravenously into the patient, and intravascular fluorescence from within the blood vessels is imaged using a video camera attached to the microscope. The patency of parent, branching, and perforating arteries and documentation of clip occlusion of the aneurysm as shown by ICG videoangiography were compared with intraoperative or postoperative findings on DS angiography. The results of ICG videoangiography corresponded with intra- or postoperative DS angiography in 90% of cases. The ICG technique missed mild but hemodynamically irrelevant stenosis that was evident on DS angiography in 7.3% of cases. The ICG technique missed angiographically relevant findings in three cases (one hemodynamically relevant stenosis and two residual aneurysm necks [2.7% of cases]). In two cases the missed findings were clinically and surgically inconsequential; in the third case, a 4-mm residual neck may require a second procedure. Indocyanine green videoangiography provided significant information for the surgeon in 9% of cases, most of which led to clip correction. CONCLUSIONS: Microscope-based ICG videoangiography is simple and provides real-time information about the patency of vessels of all sizes and about the aneurysm sac. This technique may be useful during routine aneurysm surgery as an independent form of angiography or as an adjunct to intra- or postoperative DS angiography.