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.     

Treatment of recurrent previously coiled anterior circulation aneurysm with minimally invasive keyhole craniotomy: report of two cases.

The use of minimally invasive techniques has not yet been reported for the treatment of recurrent aneurysms after coil embolization. A 47-year-old man with a long history of headaches had an anterior communicating aneurysm that had previously been coil embolized. Three-year follow-up angiography showed a significant recurrence. A 50-year-old woman with subarachnoid hemorrhage and acute visual loss underwent coil embolization of a large ophthalmic artery aneurysm, which recurred 3 months later. In both cases, a keyhole fronto-orbital one-piece craniotomy was performed. In the first patient, the aneurysm was clip ligated. The coil mass, which had eroded through the dome, was excised. In the second patient, the anterior clinoid was removed and the aneurysm was clip ligated. Postoperative angiography showed no residual aneurysm and no evidence of branch or parent vessel compromise in either patient. Both patients had an uncomplicated postoperative course. Recurrent previously coiled aneurysms are technically challenging to treat. A minimal fronto-orbital craniotomy provides a sufficiently capacious working space for successful treatment of some recurrent aneurysms of the anterior circulation.     

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.     

Routine intraoperative angiography during aneurysm surgery

OBJECT: The routine use of intraoperative angiography as an aid in the surgical treatment of aneurysms is uncommon. The advantages of the ability to visualize residual aneurysm or unintended occlusion of parent vessels intraoperatively must be weighed against the complications associated with repeated angiography and prolonged vascular access. The authors reviewed the results of their routine use of intraoperative angiography to determine its safety and efficacy. METHODS: Prospectively gathered data from all aneurysm cases treated surgically between January 1996 and June 2000 were reviewed. A total of 303 operations were performed in 284 patients with aneurysms; 24 patients also underwent postoperative angiography. Findings on intraoperative angiographic studies prompted reexploration and clip readjustment in 37 (11%) of the 337 aneurysms clipped. Angiography revealed parent vessel occlusion in 10 cases (3%), residual aneurysm in 22 cases (6.5%), and both residual lesion and parent vessel occlusion in five cases (1.5%). When compared with subsequent postoperative imaging, false-negative results were found on two intraoperative angiograms (8.3%) and a false-positive result was found on one (4.2%). Postoperative angiograms obtained in both false-negative cases revealed residual anterior communicating artery aneurysms. Both of these aneurysms also subsequently rebled, requiring reoperation. In the group that underwent intraoperative angiography, in 303 operations eight patients (2.6%) suffered complications, of which only one was neurological. CONCLUSIONS: In the surgical treatment of intracranial aneurysms, the use of routine intraoperative angiography is safe and helpful in a significant number of cases, although it does not replace careful intraoperative inspection of the surgical field.     

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.     

Parent vessel Guglielmi detachable coil herniation during wide-necked aneurysm embolization: treatment with intracranial stent placement: two technical case reports

OBJECTIVE AND IMPORTANCE: Despite recent advances in technology, parent vessel coil herniation occasionally complicates successful Guglielmi detachable coil embolization, particularly in wide-necked aneurysms. We report endovascular stent deployment performed in two patients specifically to treat this complication. CLINICAL PRESENTATION: Two patients underwent Guglielmi detachable coil embolization of cavernous segment aneurysms. Both developed coil herniation into the internal carotid artery. In one patient, the herniation occurred during the initial procedure; in the other, it was discovered in a delayed fashion during a follow-up examination for ocular symptoms. INTERVENTION: In both patients, endovascular stent deployment was performed to isolate the herniated portion of the coil from the internal carotid lumen. Follow-up angiography at 6 months demonstrated no aneurysm recanalization and no stenosis of the parent internal carotid artery in the stented region in either patient. CONCLUSION: The use of intraluminal stents has been reported to be a helpful technical adjunct to the conventional endovascular treatment of aneurysms and balloon angioplasty. One additional indication for the use of this technology is sequestering herniated coils from the lumen of the parent artery to reduce potential embolic or occlusive sequelae.     

Important factors for a combined neurovascular team to consider in selecting a treatment modality for patients with previously clipped residual and recurrent intracranial aneurysms

OBJECTIVE: Intracranial residual and recurrent aneurysms can occur after surgical clipping, with risks of growth and rupture. In the past, surgical reoperation, which can be associated with higher risk than the initial operation, was the only available treatment. A combined neurovascular team that uses both surgical and endovascular therapies could maximize efficacy and outcomes while minimizing risks in these difficult cases. The indications for which surgical or endovascular treatment should be used to treat patients with residual or recurrent aneurysms, however, have not been elucidated well. We have reviewed the 10-year experience of our combined neurovascular team to determine in a retrospective manner which factors were important to treatment modality selection for patients with these residual and recurrent lesions. METHODS: From 1991 to 2001, the combined neurovascular unit at the Massachusetts General Hospital treated 25 residual and recurrent previously clipped aneurysms (15 had been clipped at other centers). Only patients in whom a clip had been placed were included in the study; patients who did not have a clip placed or whose aneurysms were wrapped or coated were excluded. The radiographic studies and clinical data were reviewed retrospectively to determine the efficacy, outcomes, and factors important to the selection of treatment strategy in these patients. RESULTS: The patients' clinical presentations were radiographic follow-up, 17 patients; rehemorrhage, 3; mass effect, 3; and thromboembolism, 2. The mean aneurysm recurrence or residual size was 11 mm (range, 4-26 mm). The mean interval until representation was 6.6 years (range, 1 wk-25 yr). Treatment consisted of: coiling, 11 patients; reclipping, 8; proximal parent vessel balloon occlusion, 2; extracranial-intracranial bypass with coil occlusion of aneurysm and parent vessel, 2; extracranial-intracranial bypass with clip trapping, 1; and extracranial-intracranial bypass with proximal clip occlusion of parent vessel, 1. The mean radiographic follow-up period was 11 months. Complete angiographic occlusion was found in 19 aneurysms (76%), at least 90% occlusion was found in 4 aneurysms (16%), intentional partial coil obliteration was found in 1 fusiform lesion (4%), and intentional retrograde flow was found in 1 fusiform lesion (4%). Clinical outcomes were excellent or good in 19 patients (76%). Twenty-one patients (84%) were neurologically the same after retreatment (13 remained neurologically intact, and 8 had preexisting neurological deficits that did not change). Three patients (12%) had new neurological deficits after retreatment, and one patient (4%) died. There were four complications of retreatment (16%), one of which was a fatal hemorrhage in a patient 1 month after intentional partial coil obliteration of a fusiform vertebrobasilar junction aneurysm. Factors important to the selection of treatment modality were recurrence or residual location (all posterior circulation lesions were treated endovascularly), lesion size (lesions larger than 10 mm were treated endovascularly or with the use of combined techniques), and aneurysm morphology (fusiform and wide-necked lesions were treated endovascularly or with the use of combined techniques). CONCLUSION: The proper selection of surgical or endovascular treatment for residual and recurrent previously clipped aneurysms can achieve excellent radiographic efficacy with low mortality. Factors important to the selection of treatment by this combined neurovascular team were posterior circulation location, aneurysm size larger than 10 mm, and fusiform morphology, which were treated endovascularly or with the use of combined techniques because of the higher surgical risk associated with these factors. For aneurysms with lower surgical risk, such as some anterior circulation aneurysms and aneurysms smaller than 10 mm, we prefer to perform a reoperation because of superior radiographic cure without compromising the outcome.     

Intraoperative angiography evaluation of the microsurgical clipping of unruptured cerebral aneurysms

Intraoperative angiography evaluation of the clippings of cerebral aneurysms was investigated in a series of 38 consecutive patients with unruptured cerebral aneurysms to determine any favorable impact on the outcome. Unexpected findings including major arterial occlusion or residual aneurysm were identified. Specific variables such as the size and site of aneurysm were analyzed to determine the impact on clinical outcome and the incidence of clip modification. There were 11 large and 27 small aneurysms in this series. Mortality and permanent morbidity after microsurgical clipping were 0.0% and 2.6%, respectively. Unexpected angiographic findings necessitating clip repositioning consisted of residual aneurysm in two cases and distal branch occlusion or parent vessel stenosis in four. The need for clip modification was significantly higher for large than for small aneurysms (p = 0.007), and the rate of clip adjustment increased with increasing aneurysm size (p = 0.008). Intraoperative assessment prior to wound closure allows for the recognition and correction of defects and decreases the risk of postoperative complications. Intraoperative angiography may become important in the microsurgical clipping of unruptured cerebral aneurysms, especially large aneurysms.     

Endovascular treatment of distally located giant aneurysms

OBJECTIVE: Because giant aneurysms (GAs) can be technically difficult to clip, the endovascular approach is becoming increasingly popular. Endovascular treatment of distally located GAs, which often requires parent vessel occlusion, is particularly challenging because limited pathways are available for collateral flow. We aimed to determine the outcomes of endovascular attempts to treat GAs downstream from the circle of Willis. METHODS: Between 1991 and 1998, 27 patients with 27 distally located very large aneurysms or GAs were evaluated for possible endovascular treatment. Ten underwent selective embolization and 9 were treated with primary parent vessel occlusion, with or without distal bypass. Eight patients could not be treated endovascularly. RESULTS: Selective embolization resulted in only one cure. Two patients died as a result of subarachnoid hemorrhage during the follow-up period. One coil-treated patient, who underwent subsequent spontaneous parent vessel occlusion, and all nine patients treated primarily with parent vessel occlusion were considered cured after their treatments. Only two patients treated with parent vessel occlusion experienced periprocedural ischemia, which did not result in a major deficit in either case. Of the eight patients who could not be treated endovascularly, one succumbed to surgery, four died while being treated conservatively, and three were lost to follow-up monitoring. CONCLUSION: Selective aneurysm embolization is usually not curative in these situations. For selected patients, however, endovascular parent vessel occlusion is usually safe and effective in preventing the progression of symptoms and bleeding.     

Transluminal stent-assisted coil embolization of a vertebral confluence aneurysm: technique report

BACKGROUND: Recent advances in stent technology have allowed for negotiation of often tortuous posterior circulation intracranial vasculature. Stent-assisted coil embolization is a novel treatment for complex wide-necked aneurysms, as stents provide a buttress that allows for coil deposition while preventing coil herniation into the parent vessel lumen. We describe a case of stent-assisted coil embolization of a complex wide-necked vertebral confluence aneurysm. CASE DESCRIPTION: A 61-year-old woman presented with a Hunt-Hess III, Fisher Grade III subarachnoid hemorrhage secondary to a ruptured vertebral confluence aneurysm demonstrated on angiography. The patient underwent emergent angiography and attempted coiling of a vertebral confluence aneurysm. Because of the aneurysm's complex wide neck and the presence of subclavian steal syndrome, the coils repeatedly herniated into the left vertebral and basilar artery lumina. A flexible coronary stent was deployed across the aneurysm neck, preventing coil herniation and allowing for greater coil deposition. The patient tolerated the procedure and underwent repeat coiling 2 months postoperatively because of mild coil compaction. This resulted in 100% occlusion and the patient is neurologically normal except for a sixth nerve palsy which had been present after the hemorrhage. CONCLUSION: Recent advances in stent technology allow negotiation of the tortuous posterior circulation vasculature. Stent-assisted coil embolization of complex, wide-necked vertebral confluence aneurysms may be an alternative intervention for these surgically challenging lesions.     

Intracranial aneurysms treated with Guglielmi detachable coils: long-term imaging follow-up with contrast-enhanced magnetic resonance angiography

OBJECT: The aim of this study was to assess the long-term results of intracranial aneurysms treated with Guglielmi detachable coils (GDCs) with the aid of contrast-enhanced magnetic resonance (MR) angiography. METHODS: Between January 1998 and August 2001, 92 patients with 92 aneurysms treated by endovascular coiling with GDCs underwent contrast-enhanced MR angiography. These patients underwent long-term follow-up (range 32-78 months, mean 42.1 +/- 11.9 months [standard deviation]) after endovascular treatment. All images were compared with digital subtraction angiograms and contrast-enhanced MR angiograms that had been obtained during the short-term follow-up (range 5-25 months, mean 13 +/- 5.1 months after treatment). The MR angiograms were analyzed independently by 2 senior radiologists. Findings were assigned to 1 of 3 categories: complete obliteration (Class 1), residual neck (Class 2), or residual aneurysm (Class 3). RESULTS: Of 92 contrast-enhanced MR angiograms obtained at the long-term follow-up, complete obliteration of the aneurysm was noted in 57 patients (Class 1), a residual neck was seen in 22 (Class 2), and a residual aneurysm was observed in 13 (Class 3). One patient experienced aneurysm rehemorrhaging during the follow-up period. The comparison of short- and long-term follow-up angiograms demonstrated a change in aneurysm classification in 7 patients (7.6%), including 4 that progressed from Class 1 to Class 2 and 3 from Class 2 to Class 3. However, 4 (14.2%) of the 28 long-term recurrences were not detected on the short-term control images. CONCLUSIONS: Long-term follow-up with contrast-enhanced MR angiography after selective embolization of intracranial aneurysms can identify late aneurysm recanalization that is undetected at short-term follow-up.     

Endovascular occlusion of wide-necked aneurysms with a new intracranial microstent (Neuroform) and detachable coils

OBJECTIVE: The long-term durability of the endovascular occlusion of cerebral aneurysms is one of the major factors limiting the more widespread use of this technique. Long-term occlusion of wide-necked aneurysms has improved with new assistive devices that seem to improve aneurysm occlusion while protecting the parent vessel. We report the use of a new intracranial stent--the Neuroform microstent--in the treatment of patients with wide-necked cerebral aneurysms. METHODS: Patients identified as harboring wide-necked intracranial aneurysms were evaluated for stent-assisted coiling. After appropriate anticoagulation was performed, depending on whether the aneurysm was ruptured or unruptured, the Neuroform stent was delivered across the neck of the aneurysm and deployed with a coil pusher. After stent placement, standard coil occlusion of the aneurysm was achieved in the majority of cases. RESULTS: Fifty-six patients were identified as having wide-necked intracranial aneurysms suitable for stent-assisted coiling. A total of 49 aneurysms in 48 patients were treated with this procedure. In eight cases, stent deployment failed. Forty-one of the aneurysms were initially stented, followed by coil placement. Six aneurysms were stented only, and one aneurysm was initially coiled, followed by stent placement. There were five deaths (8.9%), one of which occurred secondary to a stroke after the procedure (1.8%). Four patients (7%) experienced thromboembolic events, three of which were considered to have been secondary to the procedure (5.3%). In addition, there were two femoral pseudoaneurysms. The overall complication rate was 10.7%. Five patients were available for follow-up angiographic evaluation, and their cases are discussed. CONCLUSION: Intracranial stenting may overcome important technical limitations in current endovascular therapy by improving the occlusion of wide-necked aneurysms while protecting the parent vessel.     

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

OBJECT: Three-dimensional (3D) power Doppler ultrasonography imaging provides a rapid, noninvasive visualization of ruptured intracranial aneurysms, including their relationship to other vascular structures. METHODS: The authors used transcranial 3D power Doppler imaging in the emergency room to examine patients with acute subarachnoid hemorrhage. In all patients, the ruptured aneurysm was rapidly located with 3D power Doppler imaging. Conventional x-ray angiography confirmed both the ultrasonography-based diagnosis and the location of aneurysmal bleeding. CONCLUSIONS: These preliminary results indicate that 3D power Doppler imaging is a rapid, noninvasive screening method for the visualization of ruptured aneurysms.     

Characterization of the volume data of three-dimensional CT and MR angiograms for the delineation of cerebral aneurysms

Three-dimensional CT angiography and MR angiography with perspective volume rendering were used to investigate two patients with cerebral aneurysms. Compared with the intraoperative photographs, volume data from CT angiogram and MR angiogram were characterized on simulated virtual 3D images with virtual neuro-endoscopic and transluminal imaging techniques. In a case of an unruptured double internal carotid (C2) blister aneurysm, CT angiogram showed a configuration of the distal aneurysm similar to that in the intraoperative photograph, but failed to show the margin of the proximal aneurysm adjacent to the anterior clinoid process bone due to a partial volume effect. The MR angiogram represented both aneurysms and the parent artery, including the C3-C2 internal carotid artery. The whole shape of the aneurysm, however, differed from that in the intraoperative photograph, showing instead an elongation of the aneurysmal dome. In a case of a ruptured tiny middle cerebral artery aneurysm, CT angiogram failed to show the subtle bulging of the aneurysm. In contrast, MR angiogram clearly demonstrated the bulging of the walls at the beginning of the ascending and descending branches of the M2, which is consistent with the aneurysmal convolution observed in the intraoperative photograph. In both cases, transluminal images of the 3D-CT and MR angiograms represented the intraluminal contour of the vessel and aneurysmal walls as a series of rings, and allowed a transluminal view from outside the vessel lumen through the spaces between the rings of the vessel wall. The orifices of the aneurysm and parent arteries were shown through the vessel and aneurysmal walls, providing an extensive perspective view of the angio-architecture of the aneurysm. Morphological configuration of the inner space of the vessel and aneurysm was well visualized on CT angiogram, which was consistent with the operative view. Due to a partial volume effect, the surrounding bony and venous structures overlapped with the aneurysm made them indistinguishable from each other. In contrast, the MR angiogram provided the flow-related volume information, so that dynamics of the flow in the vessel lumen visualized the elongation of the aneurysmal dome and subtle bulging of the tiny aneurysm.     

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.     

Angioscopy-assisted aneurysm clipping.

OBJECTIVE: To test the concept that endovascular angioscopy can assist surgical intracranial aneurysm clipping by providing an endoluminal view of the aneurysm-parent vessel complex. METHODS: A carotid bifurcation aneurysm was surgically created in a dog at the lingual artery origin. A balloon catheter was inflated proximal to the aneurysm to block proximal blood flow and allow endoluminal visualization. A flexible angioscope connected to a video monitoring system and to a high-intensity light source was then advanced within the catheter lumen and positioned immediately distal to the catheter tip. The aneurysm neck was clipped, and the clip was repositioned several times along the neck, with or without distal parent vessel compromise. Each time, the endovascular image on the monitor was interpreted by an observer blinded to the position of the clip. Clip position and image interpretation were communicated independently to a third person, who analyzed the correlation between them. RESULTS: Angioscopy allowed clear visualization of the extent of aneurysm neck occlusion (complete, incomplete, residual "dog ear") after clip application, as well as the presence or absence of distal parent vessel compromise. Aneurysm neck configuration, size, presence of thrombus, and suture line definition were depicted. Critical structures external to the aneurysm-parent vessel complex were transilluminated by the high-intensity lamp. CONCLUSION: Although acknowledged as the treatment of choice for intracranial aneurysms, surgical exclusion can be accompanied by significant morbidity related to perforator occlusion, parent artery compromise, and/or persistent residual aneurysm. The availability of a device allowing visualization of an aneurysm from an endoluminal perspective theoretically could reduce the incidence of these complications. Angioscopy has the potential to become a useful adjunct during intracranial aneurysm clipping because it provides real-time endoluminal viewing of the aneurysm-distal parent vessel complex, which is sometimes obscured to the surgeon.     

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.     

Delineation of cerebral aneurysms with transluminal imaging of three-dimensional MRA]

We used transluminal imaging with perspective volume rendering of magnetic resonance angiography in patients with unruptured cerebral aneurysms. Selective changes in the opacity chart of signal intensity values, based on using a spiked peak curve, represented the contour of vessels and aneurysmal walls as a series of rings, which provided a transluminal view inside and/or outside the vessel lumen through the spaces between the rings. This imaging technique allowed direct visualization of the underlying objects and offered an extensive perspective view of the architecture of an aneurysm, including an aneurysm and its parent arteries through the overlying vessel or aneurysmal walls, or through both in a single view. Transluminal imaging may be a useful adjunct modality for the intra- and extraluminal diagnosis of a cerebral aneurysm, and for simulation of the interventional and surgical procedures for cerebral aneurysms.     

Wall enhancement, edema, and hydrocephalus after endovascular coil occlusion of intradural cerebral aneurysms

OBJECT: Symptomatic local inflammation, aseptic meningitis, and hydrocephalus are reported in a group of patients treated with second generation/modified platinum coils. The purpose of this study was to define the frequency and determinants of magnetic resonance (MR) imaging findings of aneurysm wall enhancement, perianeurysmal edema, and hydrocephalus in a cohort of coil-embolized intradural cerebral aneurysms treated with bare platinum or modified platinum coils (Matrix or HydroCoils). METHODS: The authors retrospectively reviewed 359 Gd-enhanced MR follow-up studies of 181 treated aneurysms (125 ruptured) for mural enhancement. Univariate and multivariate logistic regression analyses were used to define mural enhancement associations with demographic, clinical, angiographic, treatment, and follow-up data. Embolization-related edema and hydrocephalus were defined in 95 MR imaging studies of 56 unruptured aneurysms. RESULTS: Asymptomatic wall enhancement was observed in lesions treated with all coil types, occurring in 21 (18.6%) of 113 bare platinum coil-treated aneurysms. Independent associations were HydroCoil treatment (odds ratio [OR] 9.75, 95% confidence interval [CI] 3.45-30.75) and increasing aneurysm size (OR 3.58, 95% CI 1.99-6.95). Five (8.9%) unruptured aneurysms had asymptomatic de novo edema, and 3 (5.3%) demonstrated hydrocephalus; all had been treated with HydroCoils. Hydrocephalus presentation was delayed (8-31 months) and symptomatic in 2 patients. CONCLUSIONS: Asymptomatic aneurysm wall enhancement occurred in 18.6% of embolizations performed with bare platinum coils, and probably represents a normal healing response. Perimural edema and hydrocephalus were observed only in patients treated with HydroCoils, but have been reported in patients treated with other modified platinum coils. These symptoms appear to represent an exaggerated inflammatory response during aneurysm healing. Increased vigilance for delayed hydrocephalus is required. Judicious clinical use of modified platinum coils is warranted until results of randomized trials are published.