Development of a new high-resolution intraoperative imaging system (dual-image videoangiography, DIVA) to simultaneously visualize light and near-infrared fluorescence images of indocyanine green angiography

EC-IC Bypass; Our Experience of Cerebral Revascularization with Intraoperative Dual-Image Video Angiography (Diva)

Background:

Extracranial-intracranial (EC-IC) arterial bypass has been used in the treatment of various cerebrovascular ischemic disease due to atherosclerosis or Moyamoya disease, skull base tumors encasing large IC artery or complex IC aneurysms.

Aim:

The aim is to analyze surgical technique (EC-IC bypass) and its outcome with intraoperative use of dual image video angiography (DIVA) and Doppler ultrasound.

Materials and Methods:

We studied in this article a series of 23 patients operated in Banbuntane Hotokukai Hospital, Fujita Health University, for which a superficial temporal artery-middle cerebral artery anastomosis was done for steno-occlusive disease, giant IC aneurysm or Moyamoya disease. The study was conducted between 2018 and 2020. We used dual-image video angiography (DIVA) and Doppler ultrasound to assess the luminal patency of anastomosis during the procedure.

Results:

In this study, three patients presented with Moyamoya disease, 4 had aneurysm, whereas 16 patients presented with the vascular steno-occlusive disease. The patients were divided into three categories (steno-occlusive disease, Moyamoya, and flow replacement for giant aneurysm). Dual image video angiography, along with intraoperative Doppler, helped us in the assessment of luminal patency of the anastomosis.

Conclusion:

Hemodynamic recovery after cerebrovascular bypass brings about a better outcome in ischemic stroke. The result of surgery improves with proper selection of patients with hemodynamic impairment (in Stage 2). With various modalities such as intraoperative Doppler, DIVA (Dual-image Video Angiography) and improved surgical techniques may aid in the reduction of complications and improve clinical outcome.

Intraoperative Fluorescence Cerebral Angiography by Laser Surgical Microscopy: Comparison With Xenon Microscopy and Simultaneous Observation of Cerebral Blood Flow and Surrounding Structures

BACKGROUND

Laser surgical microscopes should enable uniform illumination of the operative field, and require less luminous energy compared with existing xenon surgical microscopes.

OBJECTIVE

To examine the utility of laser illumination in fluorescence cerebral angiography.

METHODS

Fluorescein sodium (fluorescein) was used as a fluorescent dye. We first compared the clarity of cerebral blood flow images collected by fluorescence angiography between the laser illumination and xenon illumination methods. We then assessed use of the laser illuminator for simultaneous observation of blood flow and surrounding structures during fluorescence angiography. Furthermore, the study was designed to evaluate usefulness of the thus determined excitation light in clinical cases.

RESULTS

Fluorescence angiography using blue light laser for excitation provided higher clarity and contrast blood flow images compared with using blue light generated from a xenon lamp. Further, illumination with excitation light consisting of a combination of 3 types of laser (higher level of blue light, no green light, and lower level of red light) enabled both blood flow and surrounding structures to be observed through the microscope directly by the surgeon.

CONCLUSION

Laser-illuminated fluorescence angiography provides high clarity and contrast images of cerebral blood flow. Further, a laser providing strong blue light and weak red light for excitation light enables simultaneous visual observation of fluorescent blood flow and surrounding structures by the surgeon using a surgical microscope. Overall, these data suggest that laser surgical microscopes are useful for both ordinary operative manipulations and fluorescence angiography.

Indocyanine Green Angiography Visualized by Augmented Reality in Aneurysm Surgery

OBJECTIVE

We prospectively investigated how to integrate indocyanine green (ICG) angiography in an augmented reality (AR) setting for aneurysm surgery.

METHODS

In 20 patients with a total of 22 aneurysms, the head-up display of the operating microscope (Kinevo900) was used for AR. ICG-AR was established directly by the head-up display superimposing the ICG angiography as green live video overlay. In addition, the reconstructed outline of the three-dimensional (3D) vessel architecture was visualized by AR applying intraoperative low-dose computed tomography (vessel-AR).

RESULTS

In all patients, ICG-AR and vessel-AR were successfully implemented. The flow in the vessels could be observed directly in the white light view of the microscope oculars without being distracted from the surgical site by looking on separate screens. This factor enabled also surgical manipulation during ICG angiography. In parallel, AR additionally visualized the 3D vessel architecture, enhancing the understanding of the 3D anatomy (target registration error, 0.71 ± 0.21 mm; intraoperative low-dose computed tomography effective dose, 42.7 μSv). Linear (n = 28; range, 1-8.5 mm) and rotational (n = 3; range, 2.9°-14.4°) navigation adjustments performed in 18 of 20 patients resulted in a close matching of the vessel-AR outline with the real vessel situation after preparation, compensating for shifting.

CONCLUSIONS

ICG-AR could be successfully implemented. It facilitated surgical manipulation and flow interpretation during ICG angiography because it could be observed directly while looking through the microscope oculars in white light instead of being distracted from the surgical site while looking on separate screens. Additional AR visualizing the vessel architecture improved understanding of 3D anatomy for preparation and clipping.

Intraoperative Laser Speckle Contrast Imaging For Real-Time Visualization of Cerebral Blood Flow in Cerebrovascular Surgery: Results From Pre-Clinical Studies

Cerebrovascular surgery can benefit from an intraoperative system that conducts continuous monitoring of cerebral blood flow (CBF). Such a system must be handy, non-invasive, and directly integrated into the surgical workflow. None of the currently available techniques, considered alone, meets all these criteria. Here, we introduce the SurgeON™ system: a newly developed non-invasive modular tool which transmits high-resolution Laser Speckle Contrast Imaging (LSCI) directly onto the eyepiece of the surgical microscope. In preclinical rodent and rabbit models, we show that this system enabled the detection of acute perfusion changes as well as the recording of temporal response patterns and degrees of flow changes in various microvascular settings, such as middle cerebral artery occlusion, femoral artery clipping, and complete or incomplete cortical vessel cautery. During these procedures, a real-time visualization of vasculature and CBF was available in high spatial resolution through the eyepiece as a direct overlay on the live morphological view of the surgical field. Upon comparison with indocyanine green angiography videoangiography (ICG-VA) imaging, also operable via SurgeON, we found that direct-LSCI can produce greater information than ICG-VA and that continuous display of data is advantageous for performing immediate LSCI-guided adjustments in real time.

Real-Time Overlapping of Indocyanine Green—Video Angiography With White Light Imaging for Vascular Neurosurgery: Technique, Implementation, and Clinical Experience

BACKGROUND

Fluorescent-guided techniques in vascular neurosurgery can be demonstrated via black and white indocyanine green videoangiography (ICG-VA). Multispectral imaging (MFL) is a new method, which overlaps fluorescence with the white light and provides a fluorescent white light augmented reality image to the surgeon.

OBJECTIVE

To investigate (a) whether MFL can enhance the visualization of the blood-flow with simultaneous visualization of the anatomic structures and (b) if MFL can ergonomically improve the microvascular surgical treatment compared to ICG-VA.

METHODS

A digital imaging of the blood flow after intravenous injection of ICG on 7 pigs was performed in real time under white light, standard fluorescence, and MFL. The blood flow was interrupted with a surgical clip, demonstrating the blockage of the blood flow. We prospectively included 30 patients with vascular deformities. The vasculature was visualized on the microscope's monitor and through the microscope's eyepiece.

RESULTS

In the animal experiment, the visualization of the anatomy and the blood flow under MFL produced high resolution images. The occlusion of blood vessels demonstrated sufficiently the blockage of tissue perfusion and its reperfusion after clip removal. During all 30 surgical cases, the MFL technique and the direct delivery of the pseudo-colored image through the eyepiece allowed for enhanced anatomic and dynamic data.

CONCLUSION

MFL was shown to be superior to the classic ICG-VA, delivering enhanced data and notably improving the workflow due to the simultaneous and precise white light visualization of the blood flow and the surrounding anatomic structures.

Visual Outcomes after Surgery for Paraclinoid Aneurysms: A Fujita Experience

INTRODUCTION

The surgical strategies for clipping of paraclinoid aneurysms are diverse. These aneurysms are unique in their location, as they closely abut the anterior clinoid process (ACP) and the optic nerve. The ultimate goal of clipping encompasses the exposure of neck of the aneurysm which is seldom complete without the manipulation of optic nerve and the ACP. This manipulation may result in disturbances of vision postoperatively. We analyze our results of visual outcomes in the surgery for paraclinoid aneurysms in this retrospective study.

MATERIALS AND METHODS

All patients with paraclinoid aneurysms who underwent surgery from June 2014 to June 2019 were included in the study. Surgical procedure was uniform in all patients which included anterior clinoidectomy and clipping of aneurysms as per the Bantane protocol. Glasgow Outcome Scale as well as vision was assessed at discharge and at 1 month and 6 months.

RESULTS

There were 77 cases of paraclinoid aneurysms operated during the abovementioned period. All patients had no symptoms related to vision preoperatively. Visual deterioration was noted in two patients. All patients were discharged with a good outcome on the Glasgow Outcome Scale.

CONCLUSION

Paraclinoid aneurysm has a good outcome when treated with surgery. The visual deterioration following surgery can be minimized with extradural anterior clinoidectomy and careful handling of the vessels and nerve.

Multispectrum Indocyanine Green Videography for Visualizing Brain Vascular Pathology

OBJECTIVE

Currently, neurosurgical vascular surgery frequently uses indocyanine green (ICG)-videography (VG) to evaluate the blood flow in brain vessels. Although ICG-VG delineates intravascular ICG fluorescence as a high-intensity signal in gray-scale with dark background, it is hard to identify anatomical structures, including vasculature or surgical devices simultaneously. This report developed combination of a near-infrared (NIR) camera with particular sensitivity and an optical filter to observe the blood-flow conditions and anatomical structures.

METHODS

To overcome the specific issues of ICG-VG, we applied a high-sensitivity camera with a 980-nm NIR component to delineate anatomical and fluorescence images, detecting signals between 830 and 1000 nm simultaneously during operation. We used a diluted ICG phantom to evaluate fluorescence signal changes by changing wavelength of the emission light. For clinical use, we used a high-sensitivity NIR camera with a high-pass filter on a surgical microscope. The new NIR system detected signals between 770 and 1000 nm, and the lighting system illuminated objects mainly at 980-nm wavelength. Both images with the blood flow and anatomical structures were projected to the smart glasses in real time.

RESULTS

In the phantom experiment, we found that the emission light with wide band widths (575-800 nm) evoked various intensities of ICG fluorescence. This new NIR system allowed us to observe ICG fluorescence and anatomical structures without image fusion or time-delay. The both information of anatomy and fluorescence was projected on wearable smart glasses. Furthermore, the new NIR system detected ICG-fluorescence signals for a longer duration than the original camera, which allowed us to achieve careful and detailed observation of more vasculature and fine vessels.

CONCLUSIONS

This study proposes a new NIR system and emphasizes simultaneous observation of anatomy and fluorescence signals during operation. It paves the way for further possibilities in the development of optical systems. To understand the natural phenomena and combination of different scientific and clinical fields, it might be important to understand and combine not only fluorescence, but also natural science, optics, and background pathology. This simple system would be available for neuroendoscope and robotic surgery.

A Retrospective Study in Microsurgical Procedures of Large and Giant Intracranial Aneurysms: An Outcome Analysis

OBJECTIVE

Intracranial aneurysms are considered large if >10 mm and giant if >25 mm. The risk of aneurysmal rupture compounds with increase in size of the aneurysm, thus, warranting appropriate intervention. In this study, we have analyzed the outcome and effectiveness of microsurgical procedures in large and giant aneurysms.

METHODS

A retrospective analysis of all the patients who underwent microsurgical procedures for large and giant cerebral aneurysms from 2014-2018 in our institute was conducted. There were a total of 52 patients, in which direct clipping was performed in 42 (80.7%) patients, proximal trapping in 3 (5.7%) patients, trapping with bypass in 3 (5.7%) patients, suction decompression in 3 (5.7%) patients, and 1 (1.9%) patient underwent surgical reconstruction.

RESULTS

Among the 52 patients, in the postoperative period, 1 (1.9%) patient became comatose, 1 (1.9%) patient developed hemiplegia, 1 (1.9%) patient had a transient hemiparesis, and 1 (1.9%) patient had transient lower cranial nerve palsy. Two (3.8%) patients had chronic subdural hematoma during the 3-month follow-up. There was no mortality in our series.

CONCLUSIONS

There are several treatment strategies available to manage large and giant cerebral aneurysms. In this study, we had minimal morbidity (3.8%), favorable outcome (96.1%), and no mortality. Therefore, we would like to conclude that appropriate microsurgical procedures, in experienced hands, can be considered as first line in the management for large and giant intracranial aneurysms, especially those with complex anatomy, wide neck, mass effect, partial thrombosis, and the presence of critical perforating vessels from the aneurysm wall.

Carotid Endarterectomy: The Need for In vivo Optical Spectroscopy in the Decision-Making on Intraoperative Shunt Usage - A Technical Note

Background:

Carotid endarterectomy (CEA) is the surgical excision of the atherosclerotic plaque in patients with severe carotid artery stenosis. It is a common surgical technique required by neurosurgeons that should be mastered. In this article, we provide an outline of the technique and multimodality adjuncts involved in performing an effective CEA with a better surgical outcome.

Materials and Methods:

We have operated a total of 14 patients in our institute from 2015 to 2018. The male to female ratio is 13:1. Four (28.5%) patients were symptomatic and 10 (71.5%) were asymptomatic; with an average percentage of carotid stenosis being 81.2% in symptomatic and 76.6% in asymptomatic patients. Two patients have undergone bilateral CEA. Intraoperative monitoring was done with continuous in vivo optical spectroscopy (INVOS). Furui's double balloon shunt system was used to maintain blood flow from common carotid artery to the internal carotid artery, thus preventing cerebral ischemia in selected cases with significantly lateralized cerebral oximetry (CO) recordings.

Results:

Of the 14 patients with 16 CEA procedures, continuous INVOS monitoring was used in 12 CEA procedures. Of the 12 cases, only 5 (41.6%) needed a shunt. Furui's shunt was not used in 7 (58.3%) CEA procedures, where there were no changes in the intraoperative CO and these patients had an uneventful postoperative period. INVOS monitoring not only reduced the use of routine intraoperative shunt but also reduced the total surgical time and thus aided in preventing neurological complications.

Conclusion:

CEA should be strongly considered for symptomatic patients with >70% of carotid stenosis and in patients with 50%–69% stenosis if no other etiological basis for the ischemic symptoms can be identified. Continuous INVOS monitoring is mandatory for the decision of the use of intraoperative shunt, which reduces the perioperative morbidity and mortality significantly.

A Novel Intraoperative Laser Light Imaging System to Simultaneously Visualize Visible Light and Near-Infrared Fluorescence for Indocyanine Green Videoangiography

Background

Intraoperative indocyanine green videoangiography (ICG-VA) has been reported to be utilized in various cerebrovascular surgeries, wherein the blood flow is noticeably shown in white with a black background. ICG flow alone, but not other structures, can be observed using ICG-VA. We developed a novel high-resolution intraoperative imaging system using laser light source for simultaneously visualizing both visible light and near-infrared (NIR) fluorescence images of ICG-VA.

Methods

We used a novel system for 14 cerebrovascular cases. The operative field was illuminated via an operating microscope using a novel laser light source with four bands at 464 (blue), 532 (green), 640 (red), and 785 nm (NIR region). The observed light from the operative field was split using a beam splitter cube into visible (420– 660 nm) and NIR fluorescence emission light (832–900 nm). Images from the color video and NIR fluorescence emission windows were merged for visualization on a monitor screen simultaneously. Laser light was compared with xenon light, and both setups were tested for cerebrovascular surgeries.

Results

Laser light has numerous advantages over xenon light. The present setup clearly visualized the color operative field with enhanced blood flow. Complete clipping or incomplete clipping with neck remnant or remnant flow into an aneurysm was confirmed in aneurysm surgeries. Feeding arteries and draining veins were easily distinguished in case of arteriovenous malformation.

Conclusions

Using the present setup, we can observe the color operative field and enhanced blood flow using ICG in real time. This setup could facilitate various cerebrovascular surgeries.

Comparison of Near-Infrared Imaging Camera Systems for Intracranial Tumor Detection

PURPOSE

Distinguishing neoplasm from normal brain parenchyma intraoperatively is critical for the neurosurgeon. 5-Aminolevulinic acid (5-ALA) has been shown to improve gross total resection and progression-free survival but has limited availability in the USA. Near-infrared (NIR) fluorescence has advantages over visible light fluorescence with greater tissue penetration and reduced background fluorescence. In order to prepare for the increasing number of NIR fluorophores that may be used in molecular imaging trials, we chose to compare a state-of-the-art, neurosurgical microscope (System 1) to one of the commercially available NIR visualization platforms (System 2).

PROCEDURES

Serial dilutions of indocyanine green (ICG) were imaged with both systems in the same environment. Each system's sensitivity and dynamic range for NIR fluorescence were documented and analyzed. In addition, brain tumors from six patients were imaged with both systems and analyzed.

RESULTS

In vitro, System 2 demonstrated greater ICG sensitivity and detection range (System 1 1.5-251 μg/l versus System 2 0.99-503 μg/l). Similarly, in vivo, System 2 demonstrated signal-to-background ratio (SBR) of 2.6 ± 0.63 before dura opening, 5.0 ± 1.7 after dura opening, and 6.1 ± 1.9 after tumor exposure. In contrast, System 1 could not easily detect ICG fluorescence prior to dura opening with SBR of 1.2 ± 0.15. After the dura was reflected, SBR increased to 1.4 ± 0.19 and upon exposure of the tumor SBR increased to 1.8 ± 0.26.

CONCLUSION

Dedicated NIR imaging platforms can outperform conventional microscopes in intraoperative NIR detection. Future microscopes with improved NIR detection capabilities could enhance the use of NIR fluorescence to detect neoplasm and improve patient outcome.

Indocyanine Green Videoangiography in Aneurysm Surgery: Systematic Review and Meta-Analysis

BACKGROUND

Although digital subtraction angiography (DSA) may be considered the gold standard for intraoperative vascular imaging, many neurosurgical centers rely only on indocyanine green videoangiography (ICG-VA) for the evaluation of clipping accuracy. Many studies have compared the results of ICG-VA with those of intraoperative DSA; however, a systematic review summarizing these results is still lacking.

OBJECTIVE

To analyze the literature in order to evaluate ICG-VA accuracy in the identification of aneurysm remnants and vessel stenosis after aneurysm clipping.

METHODS

We performed a systematic literature review of ICG-VA accuracy during aneurysm clipping as compared to microscopic visual observation (primary endpoint 1) and DSA (primary endpoint 2). Quality of studies was assessed with the QUADAS-2 tool. Meta-analysis was performed using a random effects model.

RESULTS

The initial PubMed search resulted in 2871 records from January 2003 to April 2016; of these, 20 articles were eligible for primary endpoint 1 and 11 for primary endpoint 2. The rate of mis-clippings that eluded microscopic visual observation and were identified at ICG-VA was 6.1% (95% CI: 4.2-8.2), and the rate of mis-clippings that eluded ICG-VA and were identified at DSA was 4.5% (95% CI: 1.8-8.3).

CONCLUSION

Because a proportion of mis-clippings cannot be identified with ICG-VA, this technique should still be considered complementary rather than a replacement to DSA during aneurysm surgery. Incorporating other intraoperative tools, such as flowmetry or electrophysiological monitoring, can obviate the need for intraoperative DSA for the identification of vessel stenosis. Nevertheless, DSA likely remains the best tool for the detection of aneurysm remnants.

Intraoperative Imaging for Vascular Lesions

Neurovascular surgery is a broad and challenging, yet exciting field within neurologic surgery. The neurovascular surgeon must be meticulous; because the brain and spinal cord are unforgiving to ischemic insults. Along with the pressures of this demanding subspecialty comes the potential to help patients recover from potentially devastating pathology to go on and lead normal, healthy lives. Several intraoperative imaging modalities are available to help maximize treatment success while reducing risk. This article reviews each of these modalities, including digital subtraction angiography, fluorescence angiography, Doppler ultrasonography, laser Doppler, laser speckle contrast imaging, neuronavigation, and neuroendoscopy.

Dual-Image Videoangiography During Intracranial Microvascular Surgery

OBJECTIVE

Indocyanine green videoangiography (ICG-VA) is a valuable tool to assess vessel and aneurysm patency during neurovascular surgical procedures. However, ICG-VA highlights vascular structures, which appear white over a black background. Anatomic relationships are sometimes difficult to understand at first glance. Dual-image videoangiography (DIVA) enables simultaneous visualization of light and near-infrared fluorescence images of ICG-VA.

METHODS

The DIVA system was mounted on an OPMI Pentero Flow 800 intraoperative microscope. DIVA was used during microsurgical procedures on 5 patients who were operated for aneurysm clipping and superficial temporal artery-middle cerebral artery bypass.

RESULTS

DIVA provides real-time simultaneous visualization of aneurysm and vessels and surrounding structures including brain, nerves, and surgical clips. Although visual contrast between vessels and background is higher with standard black-and-white imaging, DIVA makes it easier to understand anatomic relationships between intracranial structures. DIVA also provides better vision of the depth of field.

CONCLUSIONS

DIVA has the potential to become a widely used intraoperative tool to check patency of intracranial vessels. It should be considered as an adjunct to standard ICG-VA for better understanding of vascular anatomy in relation to surrounding structures and can have an impact on decision making during surgery.