Application of intraarterial superselective indocyanine green angiography in bypass surgery for adult moyamoya disease.

Background: Extracranial-intracranial (EC-IC) bypass surgery is the main treatment approach to moyamoya disease, and an accurate assessment of the patency of anastomosis is critical for successful surgery. So far, the most common way to do this is the intraoperative intravenous indocyanine green (ICG) video-angiography. Intra-arterial ICG-VA has been applied to treat peripheral cerebral aneurysms, spinal arteriovenous fistulas, and dural arteriovenous fistulas, but few reports have concerned the use of arterial injection of ICG to evaluate anastomotic patency. This research aims to explore the feasibility and effects of catheter-guided superficial temporal artery injection of ICG in the evaluation of anastomotic patency after bypass surgery. Methods: In this study, 20 patients with moyamoya disease or syndrome who underwent bypass surgery were divided into two groups, one who received intravenous ICG angiography and the other who received intra-arterial ICG angiography, to compare the two injection methods for vascular anastomosis patency. We conducted conventional intraoperative digital subtraction angiography (DSA) in a hybrid operating room during extracranial-intracranial (EC-IC) bypass surgery, including the additional step of injecting ICG into the main trunk of the superficial temporal artery (STA) through a catheter. Results: Intra-arterial injection of indocyanine green video-angiography (ICG-VA) indicated good patency of the vascular anastomosis when compared with conventional digital subtraction angiography (DSA) and intravenous ICG-VA, confirming the feasibility of using the arterial injection of ICG for assessing anastomotic patency. And intra-arterial ICG-VA results in faster visualization than intravenous ICG-VA (p < 0.05). Besides, ICG-VA through arterial injection provided valuable information on the vascular blood flow direction after the bypass surgery, and allowed for visual inspection of the range of cortical brain supply from the superficial temporal artery and venous return from the cortex. Moreover, arterial injection of ICG offered a rapid dye washout effect, reducing the repeat imaging time. Conclusion: This study indicates that intra-arterial ICG-VA has good effects in observing the direction of blood flow in blood vessels and the range of cortical brain supply from the STA, which reflects blood flow near the anastomosis and provides additional information that may allow the postoperative prediction of cerebral hyperperfusion syndrome. However, the procedure of intra-arterial ICG-VA is relatively complicated compared to intravenous ICG-VA.

Intraoperative DSA-guided minimal approach for craniocervical junction DAVFs obliteration.

BACKGROUND: Dural arteriovenous fistulas (DAVFs) are a group of diseases involving problematic shunts between dural arteries and venous structures such as sinuses, meningeal veins, or even cortical veins. To focus on craniocervical junction dural arteriovenous fistulas (DAVFs), we introduce a minimally invasive technique with midline incision combined with intraoperative digital subtraction angiography (DSA). This hybrid technique can minimize the incision wound to an average of 6 cm which leads to less destruction and lower risk of adverse events. METHOD: Using this minimally invasive approach, surgical obliteration was achieved in 6 patients with craniocervical junction DAVFs. A minimal midline incision was made over the C1-2 level, measuring approximately 5 to 7 cm in length. C1 hemilaminectomy was performed for DAVF obliteration followed by intraoperative DSA for confirmation of complete obliteration. RESULTS: Among these 6 patients, the radiculomedullary artery was the most common feeding artery. The mean length of the operation (including DSA performance) was 6.5 ± 1.4 h. None of these cases showed cerebrospinal fluid leakage or exacerbation of neurological symptoms after the operation. CONCLUSION: Using intraoperative DSA, the minimally invasive technique offers more precise but less destructive access than conventional far lateral suboccipital craniotomy. Most importantly, intraoperative DSA provided verification of complete closure for shunts that could not be examined for indocyanine green (ICG) dye because the microscope did not have a clear line of sight. In our experience, this technique shows encouraging results of fistula obliteration.

Efficacy of Utilizing Both 3-Dimensional Multimodal Fusion Image and Intra-Arterial Indocyanine Green Videoangiography in Cerebral Arteriovenous Malformation Surgery.

OBJECTIVE: An understanding of the complex morphology of an arteriovenous malformation (AVM) is important for successful resection. We have previously reported the utility of intra-arterial indocyanine green (ICG) videoangiography for this purpose, but that method cannot detect the angioarchitecture covered by brain tissue. 3-dimensional (3D) multimodal fusion imaging is reportedly useful for this same purpose, but cannot always visualize the exact angioarchitecture due to poor source images and processing techniques. This study examined the results of utilizing both techniques in patients with AVMs. METHODS: Both techniques were applied in 12 patients with AVMs. Both images were compared with surgical views and evaluated by surgeons. RESULTS: Although evaluations for identifying superficial feeders by ICG videoangiography were high in all cases, the more complicated the AVM, the lower the evaluation by 3D multimodal fusion imaging. Conversely, evaluation of the estimated range of the nidus was high in all cases by 3D multimodal fusion imaging, but low in all but one case by ICG videoangiography. Nidus flow reduction was recognized by Flow 800 analysis obtained after ICG videoangiography. CONCLUSIONS: These results showed that utilizing both techniques together was more useful than each modality alone in AVM surgery. This was particularly effective in identifying superficial feeders and estimating the range of the nidus. This technique is expected to offer an optimal tool for AVM surgery.

The Role of Bypass Surgery for the Management of Complex Intracranial Aneurysms in the Anterior Circulation in the Flow-Diverter Era: A Single-Center Series.

Despite the increasing popularity of flow diverters (FDs) as an endovascular option for intracranial aneurysms, the treatment of complex aneurysms still represents a challenge. Combined strategies using a flow-preservation bypass could be considered in selected cases. In this study, we retrospectively reviewed our series of patients with complex intracranial aneurysms submitted to bypass. From January 2015 to May 2022, 23 patients were selected. We identified 11 cases (47.8%) of MCA, 6 cases (26.1%) of ACA and 6 cases (26.1%) of ICA aneurysms. The mean maximal diameter was 22.73 ± 12.16 mm, 8 were considered as giant, 9 were fusiform, 8 presented intraluminal thrombosis, 10 presented wall calcification, and 18 involved major branches or perforating arteries. Twenty-five bypass procedures were performed in 23 patients (two EC-IC bypasses with radial artery graft, seventeen single- or double-barrel STA-MCA bypasses and six IC-IC bypasses in anterior cerebral arteries). The long-term bypass patency rate was 94.5%, and the total aneurysm exclusion was 95.6%, with a mean follow-up of 28 months. Median KPS values at last follow-up was 90, and a favorable outcome (KPS ≥ 70 and mRS ≤ 2) was obtained in 87% of the cases. The use of bypass techniques represents, in selected cases, a valid therapeutic option in the management of complex anterior circulation aneurysms when a simpler direct approach, including the use of FD, is considered not feasible.

Efficacy of intraarterial indocyanine green videoangiography in surgery for arteriovenous fistula at the craniocervical junction in a hybrid operating room: illustrative cases.

BACKGROUND: Sufficient understanding of the angioarchitecture of an arteriovenous fistula (AVF) at the craniocervical junction (CCJ) is crucial to surgical treatment but is often difficult because of the complex vascular anatomy. Intraarterial indocyanine green (ICG) videoangiography has emerged as a more useful option for understanding the vascular anatomy than intravenous ICG videoangiography. This report describes two cases of CCJ AVFs successfully treated by surgery using intraarterial ICG videoangiography and describes the efficacy of this technique. OBSERVATIONS: Case 1 involved a 71-year-old man presenting with tetraparesis after sudden onset of severe headache due to subarachnoid hemorrhage (SAH). Digital subtraction angiography (DSA) demonstrated CCJ epidural AVF. Intraarterial ICG videoangiography revealed the drainer, which had been difficult to identify. The AVF disappeared after disconnection of the drainer. Case 2 involved a 68-year-old man presenting with severe headache due to SAH. DSA showed multiple AVFs at the CCJ and cerebellar tentorium. Intraarterial ICG videoangiography demonstrated concomitant perimedullary AVF and dural AVF at the CCJ. All AVFs disappeared postoperatively. LESSONS: Intraarterial ICG videoangiography was useful for definitive diagnosis of CCJ AVF, facilitating identification of feeders and drainers with bright and high phase contrast and allowing repeated testing to confirm flow direction.

Role of Indocyanine Green with FLOW 800 in Removal of Hidden Arteriovenous Malformations.

OBJECTIVE: Indocyanine green videoangiography (ICG-VA) with FLOW 800 (Carl Zeiss AG) has been used as a visualization tool to guide arteriovenous malformation (AVM) surgery since 2011. We performed a systematic review and evaluated the quality of evidence available on this topic. In addition, we present a series of our own cases demonstrating the unique use of ICG-VA in the localization and removal of deeper seated AVMs. METHODS: Using the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines for systematic reviews, we identified studies related to ICG-VA with FLOW 800 in AVM surgeries using search terms. The studies were screened and reviewed, and the quality of evidence was analyzed using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) criteria. We performed a retrospective review of our own cases of AVM removal with ICG-VA and FLOW 800. RESULTS: Our search revealed 27 relevant studies, 17 of which met our inclusion criteria. The quality of the body of evidence was determined to be "very low" using the GRADE criteria. We used ICG-VA with FLOW 800 analysis for 14 cases of microsurgical AVM removal. This technique provided unique insights into the localization of deep seated AVMs in 8 cases (57%). No residual AVM was found when assessed by the 6-month follow-up angiogram. CONCLUSIONS: We present cases highlighting the usefulness of this technique for the localization of certain AVMs. We believe the use of ICG-VA can guide the removal of deeper seated AVMs, because it can reveal surface feeders and draining veins that can be followed to a hidden nidus. Larger, registry-based studies are needed to confirm these findings and improve the overall quality of evidence.

Efficacy of Intra-arterial Indocyanine Green Videoangiography in Hemangioblastoma Surgery: A Case Report.

Intravenous indocyanine green (ICG) videoangiography is reportedly useful for vascular neurosurgery, and for treating hemangioblastoma due to its high vascularity. Videoangiography obtained after intra-arterial ICG injection has emerged as a more useful option than that after intravenous injection. This report offers the first description of a case of hemangioblastoma successfully treated using intra-arterial ICG videoangiography, and describes the efficacy of this technique. A 20-year-old man presented with progressive cerebellar ataxia and dysphagia. Magnetic resonance imaging (MRI) revealed an enhanced solid tumor in the medulla oblongata. Digital subtraction angiography (DSA) showed a highly vascularized tumor. Surgery was performed to remove the tumor in a hybrid operating room. A catheter was introduced into the vertebral artery (VA) for intra-arterial ICG videoangiography. Superficial feeders and drainers were identified and flow dynamic changes in the tumor were assessed by intra-arterial ICG videoangiography. The tumor was removed after confirming lack of flow in the drainer. Intra-arterial ICG videoangiography was more useful than intravenous ICG videoangiography in hemangioblastoma surgery for identifying feeders and drainers and assessing flow dynamics in the tumor. Use of Flow 800 made these findings simpler and easier to evaluate.

Basic research and surgical techniques for brain arteriovenous malformations.

Arteriovenous malformations (AVMs) are hemorrhagic vascular diseases in which arteries and veins are directly connected with no capillary bed between the two. We herein introduce the results of basic research of this disease and surgical techniques based on our data and experiences. The results obtained from our research show that cell death- and inflammation-related molecules changed or became activated compared with control specimens. These findings indicate that chronic inflammation occurs in and around the nidus of AVMs. Various molecules are involved in the mechanisms of cell death and angiogenesis during this process. Confirmation of blood flow in the nidus is very important to avoid hemorrhagic complications during surgical removal of the nidus. The risk of hemorrhage increases when the blood flow in the nidus is not reduced. We reported the advantages of serial indocyanine green videoangiography, which is used to assess the blood flow during AVM nidus removal. Since publication of the ARUBA trial and Scottish Audit, treatments with high morbidity have not been allowed. It is especially important for neurosurgeons to treat low Spetzler-Martin grade AVMs with low morbidity. J. Med. Invest. 67 : 222-228, August, 2020.

In Situ Side-to-Side Pericallosal-Pericallosal Artery and Callosomarginal-Callosomarginal Artery Bypasses for Complex Distal Anterior Cerebral Artery Aneurysms: A Technical Note.

BACKGROUND: Despite surgical and endovascular technical improvements over the last decades, the treatment of complex aneurysms of the distal anterior cerebral artery (ACA) is very challenging for both vascular neurosurgeons and interventional neuroradiologists. Furthermore, the interpersonal anatomic variability requires, most of the time, a tailored planning. OBJECTIVE: To describe a novel technique of bypasses in the territory of ACA to protect the brain territory distal to the aneurysm. METHODS: A 53-yr-old male with a large complex fusiform aneurysm of the left distal A2 segment of the ACA, involving the origin of the callosomarginal and pericallosal arteries, was judged not suitable for a single procedure (endovascular or neurosurgical). Two side-to-side bypasses were performed in a single surgery to connect the pericallosal and callosomarginal arteries of both sides, distally to the aneurysm. Subsequently, an endovascular embolization of the aneurysm was achieved with coils. RESULTS: The patency of the microanastomoses, performed in the anterior interhemispheric fissure, was positively evaluated intraoperatively with indocyanine green and fluorescein videoangiography. The aneurysm sac, together with proximal A2 segment, was completely occluded with platinum coils. At the last follow-up, computed tomography angiography confirmed the patency of both bypasses, without any sign of aneurysm recanalization. The patients never complained of any focal neurological deficits or worsening of clinical status. CONCLUSION: We present an elegant and innovative solution to completely protect the distal ACA territory in cases of complex aneurysm involving the origin of both callosomarginal and pericallosal arteries.

Efficacy of intraarterial superselective indocyanine green videoangiography in cerebral arteriovenous malformation surgery in a hybrid operating room.

OBJECTIVE: Although intravenous indocyanine green (ICG) videoangiography has been reported to be useful when applied to cerebral arteriovenous malformation (AVM) surgery, the ICG that remains after the procedure makes it difficult to understand the anatomy, to evaluate nidus blood flow changes, and to repeat ICG videoangiography within a short time. Intraarterial ICG videoangiography has emerged as a way to overcome these limitations. The current study presents the results of intraarterial ICG videoangiography undertaken in patients with cerebral AVMs. METHODS: Intraarterial ICG videoangiography was performed in 13 patients with cerebral AVMs. Routine intraoperative digital subtraction angiography at the authors' institution is performed in a hybrid operating room during AVM surgery and includes the added step of injecting ICG to the contrast medium that is administered through a catheter. RESULTS: Predissection studies were able to visualize the feeder in 12 of 13 cases. The nidus was visualized in 12 of 13 cases, while the drainer was visualized in all cases. After total dissection of the nidus, there was no ICG filling in the drainers found in any of the cases. Washout of the ICG took 4.4 ± 1.3 seconds in the feeders, 9.2 ± 3.5 seconds in the drainers, and 20.9 ± 3.4 seconds in all of the vessels. Nidus flow reduction was confirmed during dissection in 9 of 9 cases. Flow reduction was easy to recognize due to each span being very short. Color-encoded visualization and objective data obtained by Flow 800 analysis reinforced these findings. CONCLUSIONS: The results showed that intraarterial ICG videoangiography was more useful than intravenous ICG videoangiography in cerebral AVM surgery. This was especially effective in the identification of the feeder, nidus, and drainer and in the assessment of the flow dynamics of the nidus. Use of Flow 800 made it simpler and easier to evaluate these findings.

Indocyanine Green and Contrast-Enhanced Ultrasound Videoangiography: A Synergistic Approach for Real-Time Verification of Distal Revascularization and Aneurysm Occlusion in a Complex Distal Middle Cerebral Artery Aneurysm.

BACKGROUND: Distal outflow occlusion and extracranial-intracranial bypass represent a possible option for the surgical management of complex middle cerebral artery (MCA) aneurysm. A limitation of the distal clipping strategy combined to bypass is related to the difficulties in predicting intraoperatively the good blood flow supply to the brain territory distal to the aneurysm and the extent and speed of aneurysmal thrombosis. METHODS: We present an innovative approach in which contrast-enhanced ultrasound (CEUS) and indocyanine green videoangiography (ICG-VA) have been synergistically used to study the effect of distal clipping on the aneurysm flow and the parenchymal blood flow after the bypass. We used this approach in a patient harboring a fusiform, partially thrombosed distal left MCA aneurysm. RESULTS: The patient was treated by a superficial temporal artery-MCA bypass, followed by MCA clipping immediately distally to the aneurysm. ICG-VA was used to evaluate bypass patency and brain perfusion in the area supplied by the bypass. CEUS was used to confirm the characteristics of the aneurysm and to explore the proximal MCA compartment immediately after dural opening, and to verify in real time the effect on aneurysm flow determined by distal outflow occlusion. Postoperative imaging confirmed aneurysm occlusion and patency of the bypass. The patient did not experience any neurologic sequelae. CONCLUSIONS: We present the first report of a synergistic intraoperative utilization of ICG-VA and CEUS in studying parenchymal perfusion and aneurysm flow in complex neurovascular procedures.

Usefulness of dural surface tracing of the cortical vessels with indocyanine green videoangiography just prior to dural opening for various cerebrovascular diseases.

BACKGROUND: Indocyanine green (ICG) videoangiography can be used to delineate the locations of the cortical vessels just prior to dural opening, allowing safe and optimal dural opening. The present clinical series demonstrates the adjunct use of ICG videoangiography to optimize dural opening for the treatment of various cerebrovascular diseases. METHODS: A total of 45 patients underwent surgery for superficial temporal artery-middle cerebral artery bypass (40), arteriovenous malformation (2), and dural arteriovenous fistula (3) between January 2012 and December 2016. After the dura had been exposed, ICG (0.25 mg/kg) was administered intravenously from the peripheral vein as a bolus just prior to dural opening. The operating microscope equipped with a fluorescent filter was used to examine the illuminated field of interest, and real-time flow assessment of the underlying cortical vessels and/or dural sinus was performed. The target recipient arteries for anastomosis or vascular malformations were visualized through the dura and marked using a pyoktanin pen on the dura mater. RESULTS: The optimal dural opening was performed for anastomosis, and safety was ensured by locating the vascular malformations through the dura mater in all cases. The cortical vessel injury was avoided in all cases. No complication was related to this procedure. CONCLUSIONS: Dural surface tracing of the cortical vessels with ICG videoangiography just prior to dural opening is a useful technique, which allows optimal and safe dural opening for treatment of various cerebrovascular diseases.

Indocyanine Green (ICG) Videoangiography-Guided Dissection of the Sylvian Fissure on the Transsylvian Approach: Technical Note.

BACKGROUND: The transsylvian approach is a standard method of approach for anterior circulation aneurysms or paraclinoid tumors. Care must be taken, however, to avoid inadvertent obliteration of sylvian veins to prevent postoperative brain swelling and venous infarction. Sometimes, the superficial sylvian veins have complex connections or are not visible because of the thickness of the arachnoid membrane, especially in the case of subarachnoid hemorrhage (SAH). The present report describes a simple method to dynamically visualize the sylvian vein via indocyanine green (ICG) angiography for the purposes of appropriately wide dissection of the sylvian fissure. METHODS: Before dissection of the sylvian fissure and after opening the dura mater, a bolus of ICG is administered intravenously. ICG videoangiography is used for dynamic venography at 10 seconds after the depiction of branches of the middle cerebral artery. RESULTS: Clear documentation of the sylvian vein was obtained via ICG videoangiography, even in cases of SAH with ambiguous anatomical topography attributable to clot under the superficial arachnoid membrane. ICG was able to differentiate between the sylvian veins of the frontal and temporal lobes, which allowed wide dissection of the sylvian fissure while preserving the veins. CONCLUSIONS: ICG videoangiography is an easy and useful method for identifying the connections and tributaries of the superficial sylvian veins from a transsylvian approach. This method allows wide opening of the sylvian fissure while preserving the sylvian veins.

Visualization of declamping procedure during carotid endarterectomy by ICG videoangiography.

BACKGROUND: ICG videoangiography (ICG-VAG) is widely used in neurovascular surgery. In carotid artery disease, it has been used to assess the extent of the plaque and to confirm the removal of the plaque and patency of the artery. We introduce a novel usage of the ICG-VAG to confirm the patency of the external carotid artery (ECA) and superior thyroid artery (STA), which should work as a drainage system of possible debris in the lumen. METHOD: Consecutive 27 patients with severe internal carotid artery stenosis were employed. Carotid endarterectomy (CEA) was done in the usual fashion. After suturing the arteriotomy, ICG was injected intravenously before reperfusion. Before declamping procedure, ICG-VAG mode was started. As the declamping procedure went on, the assistant judged whether the STA and the ECA were patent by watching the ICG flow on the monitor. After confirming the patency of the ECA-CCA system, the ICA was reperfused. RESULT: The back flow from the STA was not confirmed in two cases. The back flow from the ECA was confirmed in all 27 cases. In four cases, the ICG-VAG showed air bubbles in the lumen; these bubbles were washed away to the ECA or STA. CONCLUSION: Using ICG-VAG during the reperfusion procedure of CEA, the patency of the ECA and the STA can be confirmed. It may contribute to reduce embolic complication during reperfusion procedure.

A prospective comparative study of microscope-integrated intraoperative fluorescein and indocyanine videoangiography for clip ligation of complex cerebral aneurysms.

OBJECT: The authors prospectively analyzed 2 microscope-integrated videoangiography techniques using intravenous indocyanine green (ICG) and fluorescein for assessment of cerebral aneurysm obliteration and adjacent vessel patency. METHODS: The authors prospectively enrolled 22 patients who underwent clip ligation of their aneurysm and used intraoperative videoangiography to assess obliteration of the aneurysmal sac and patency of the adjacent branching and perforating arteries. Patients underwent ICG videoangiography (ICG-VA) and the newly developed fluorescein videoangiography (FL-VA) using microscope-integrated fluorescence modules. Two independent observers compared the videoangiography recordings for value and quality to assess aneurysm exclusion and the patency of adjacent arteries. RESULTS: All 22 patients first underwent FL-VA and then ICG-VA after clip application. In 7 cases (32%), FL-VA provided superior detail to assess perforating arteries (4 cases), distal branches (2 cases), and both (1 case); such detail was not readily available on ICG-VA. In 1 patient, ICG-VA offered better visualization of posterior communicating artery aneurysm occlusion than FL-VA because of staining artifact on the aneurysm dome from the adjacent tentorium. In 2 patients, FL-VA offered the needed advantage of real-time manipulation of the vessels and flow assessment by visualization through the operating microscope oculars. In 2 other cases, ICG-VA was more practical for repeat usage because of its more efficient clearance from the intravascular space. The ICG-VA image quality was often degraded at higher magnification in deep operative fields, partly due to chromatic aberration. Both ICG-VA and FL-VA afforded restricted views of vasculature based on the angle of surgical approach and obscuration by blood clot, aneurysm, or brain tissue. CONCLUSIONS: Compared with ICG-VA, FL-VA can potentially provide an improved visualization of vasculature at high magnification in deep surgical fields. ICG-VA is more effective for repeated use during clip repositioning due to ICG's minimal vascular wall extravasation. Therefore, in certain cases, FL-VA may offer some advantages and play a complementary role along with ICG-VA in intraoperative fluorescence evaluation during microsurgical management of aneurysms.

Indocyanine green videoangiography for confirmation of bypass graft patency.

OBJECTIVE: The aim of the study is to determine the efficacy of indocyanine green (ICG) videoangiography for confirmation of vascular anastomosis patency in both extracranial-intracranial and intracranial-intracranial bypasses. METHODS: Intraoperative ICG videoangiography was used as a surgical adjunct for 56 bypasses in 47 patients to assay the patency of intracranial vascular anastomosis. These patients underwent a bypass for cerebral ischemia in 31 instances and as an adjunct to intracranial aneurysm surgery in 25. After completion of the bypass, ICG was administered to assess the patency of the graft. The findings on ICG videoangiography were then compared to intraoperative and/or postoperative imaging. RESULTS: ICG provided an excellent visualization of all cerebral arteries and grafts at the time of surgery. Four grafts were determined to be suboptimal and were revised at the time of surgery. Findings on ICG videoangiography correlated with intraoperative and/or postoperative imaging. CONCLUSION: ICG videoangiography is rapid, effective, and reliable in determining the intraoperative patency of bypass grafts. It provides intraoperative information allowing revision to reduce the incidence of technical errors that may lead to early graft thrombosis.

Indocyanine Green Videoangiography for Confirmation of Bypass Graft Patency

OBJECTIVE: The aim of the study is to determine the efficacy of indocyanine green (ICG) videoangiography for confirmation of vascular anastomosis patency in both extracranial-intracranial and intracranial-intracranial bypasses. METHODS: Intraoperative ICG videoangiography was used as a surgical adjunct for 56 bypasses in 47 patients to assay the patency of intracranial vascular anastomosis. These patients underwent a bypass for cerebral ischemia in 31 instances and as an adjunct to intracranial aneurysm surgery in 25. After completion of the bypass, ICG was administered to assess the patency of the graft. The findings on ICG videoangiography were then compared to intraoperative and/or postoperative imaging. RESULTS: ICG provided an excellent visualization of all cerebral arteries and grafts at the time of surgery. Four grafts were determined to be suboptimal and were revised at the time of surgery. Findings on ICG videoangiography correlated with intraoperative and/or postoperative imaging. CONCLUSION: ICG videoangiography is rapid, effective, and reliable in determining the intraoperative patency of bypass grafts. It provides intraoperative information allowing revision to reduce the incidence of technical errors that may lead to early graft thrombosis.