Improved visualization of intracranial vessels with intraoperative coregistration of rotational digital subtraction angiography and intraoperative 3D ultrasound

Challenges with segmenting intraoperative ultrasound for brain tumours

Objective - Addressing the challenges that come with identifying and delineating brain tumours in intraoperative ultrasound. Our goal is to both qualitatively and quantitatively assess the interobserver variation, amongst experienced neuro-oncological intraoperative ultrasound users (neurosurgeons and neuroradiologists), in detecting and segmenting brain tumours on ultrasound. We then propose that, due to the inherent challenges of this task, annotation by localisation of the entire tumour mass with a bounding box could serve as an ancillary solution to segmentation for clinical training, encompassing margin uncertainty and the curation of large datasets. Methods - 30 ultrasound images of brain lesions in 30 patients were annotated by 4 annotators - 1 neuroradiologist and 3 neurosurgeons. The annotation variation of the 3 neurosurgeons was first measured, and then the annotations of each neurosurgeon were individually compared to the neuroradiologist's, which served as a reference standard as their segmentations were further refined by cross-reference to the preoperative magnetic resonance imaging (MRI). The following statistical metrics were used: Intersection Over Union (IoU), Sørensen-Dice Similarity Coefficient (DSC) and Hausdorff Distance (HD). These annotations were then converted into bounding boxes for the same evaluation. Results - There was a moderate level of interobserver variance between the neurosurgeons [ I o U : 0.789 , D S C : 0.876 , H D : 103.227 ] and a larger level of variance when compared against the MRI-informed reference standard annotations by the neuroradiologist, mean across annotators [ I o U : 0.723 , D S C : 0.813 , H D : 115.675 ] . After converting the segments to bounding boxes, all metrics improve, most significantly, the interquartile range drops by [ I o U : 37 % , D S C : 41 % , H D : 54 % ] . Conclusion - This study highlights the current challenges with detecting and defining tumour boundaries in neuro-oncological intraoperative brain ultrasound. We then show that bounding box annotation could serve as a useful complementary approach for both clinical and technical reasons.

Utilizing Intraoperative Navigated 3D Color Doppler Ultrasound in Glioma Surgery

Background

In glioma surgery, the patient’s outcome is dramatically influenced by the extent of resection and residual tumor volume. To facilitate safe resection, neuronavigational systems are routinely used. However, due to brain shift, accuracy decreases with the course of the surgery. Intraoperative ultrasound has proved to provide excellent live imaging, which may be integrated into the navigational procedure. Here we describe the visualization of vascular landmarks and their shift during tumor resection using intraoperative navigated 3D color Doppler ultrasound (3D iUS color Doppler).

Methods

Six patients suffering from glial tumors located in the temporal lobe were included in this study. Intraoperative computed tomography was used for registration. Datasets of 3D iUS color Doppler were generated before dural opening and after tumor resection, and the vascular tree was segmented manually. In each dataset, one to four landmarks were identified, compared to the preoperative MRI, and the Euclidean distance was calculated.

Results

Pre-resectional mean Euclidean distance of the marked points was 4.1 ± 1.3 mm (mean ± SD), ranging from 2.6 to 6.0 mm. Post-resectional mean Euclidean distance was 4.7. ± 1.0 mm, ranging from 2.9 to 6.0 mm.

Conclusion

3D iUS color Doppler allows estimation of brain shift intraoperatively, thus increasing patient safety. Future implementation of the reconstructed vessel tree into the navigational setup might allow navigational updating with further consecutive increasement of accuracy.

The Use of Real-Time 3D Intraoperative Ultrasound "Angiography" in Localization and Occlusion Control of a Ruptured Mycotic Aneurysm: A Case Report

BACKGROUND

 Infectious (mycotic) aneurysms are rare with high mortality and are most commonly found at the distal branches of the middle cerebral artery (MCA). Because aneurysms of the distal MCA are located deep in the Sylvian fissure and are small in size, intraoperative identification and safe clip occlusion of these aneurysms are challenging. Thus, the use of intraoperative imaging and navigation can be beneficial. We describe the use of intraoperative real-time 3D ultrasound "angiography" (3D-iUS) in localizing and occlusion control of a ruptured MCA M3 segment mycotic aneurysm. To our knowledge, its application in the surgery of a ruptured mycotic distal MCA aneurysm is not yet reported.

CLINICAL PRESENTATION

 A 54-year-old woman with a history of septic thrombophlebitis treated with long-term antibiotic therapy presented with sudden onset of headaches, dysphasia, and seizures. Computed tomography (CT) revealed subarachnoid hemorrhage in the distal portion of the left Sylvian fissure. Digital subtraction angiography (DSA) showed an aneurysm at the peripheral branch of the M3 segment of the MCA with characteristics of an infectious aneurysm. A microsurgical treatment was decided. 3D-iUS scan showed an aneurysm within the Sylvian fissure at a depth of 5 cm. The aneurysm was clipped and a repeated 3D-iUS scan showed total occlusion of the aneurysm and patency of the parent artery. The intraoperative findings were confirmed with a postoperative DSA.

CONCLUSION

 Our case report shows that real-time 3D-iUS, despite its limitations, is an important tool to locate and ascertain the successful clip occlusion of an aneurysm, especially when intraoperative angiography (IA) and indocyanine green (ICG) videoangiography are not available due to low-income settings.

Vessel Segmentation of X-Ray Coronary Angiographic Image Sequence

OBJECTIVE

To facilitate the analysis and diagnosis of X-ray coronary angiography in interventional surgery, it is necessary to extract vessel from X-ray coronary angiography. However, vessel images of angiography suffer from low quality with large artefacts, which challenges the existing vascular technology.

METHODS

In this paper, we propose a ávessel framework to detect vessels and segment vessels in angiographic vessel data. In this framework, we develop a new matrix decomposition model with gradient sparse in the tensor representation. Then, the energy function with the input of the hierarchical vessel is used in vessel detection and vessel segmentation.

RESULTS

Through experiments conducted on angiographic data, we have demonstrated the good performance of the proposed method in removing background structure.

CONCLUSION

We evaluated our method for vessel detection and segmentation in different clinical settings, including LAO/RAO with cranial and caudal angulation, and showed its competitive results compared with eight state-of-the-art methods in terms of extensive qualitative and quantitative evaluation.

SIGNIFICANCE

Our method can remove a large number of background artefacts and obtain a better vascular structure, which has contributed to the clinical diagnosis of coronary artery diseases.

Reliability of dual- vs single-volume reconstruction of three-dimensional digital subtraction angiography for follow-up evaluation of endovascularly treated intracranial aneurysms

INTRODUCTION

Single-volume reconstruction of three-dimensional (3D) digital subtraction angiography (DSA) can be effectively used for aneurysm assessment and planning of endovascular embolization. Unfortunately, post-embolization follow-up angiographic images can be obscured by artifact. The dual-volume reconstruction technique was developed in order to reduce artifact and enhance the visualization of the aneurysm, the parent vessel and side branches, and endovascular devices. The purpose of this study was to compare the reliability of dual- vs single-volume reconstruction of 3D DSA in evaluation of follow-up images after endovascular embolization of intracranial aneurysms.

METHOD

Four cerebrovascular neurosurgeons independently and blindly reviewed 20 randomly selected dual-and single-volume reconstructions of 3D DSAs demonstrating cerebral aneurysms treated with primary coil embolization, stent-assisted coil embolization, or Pipeline embolization. Five images were repeated for each modality (single and dual volume) in order to assess intra-rater reliability. The intraclass correlation coefficient was calculated as a measure of the overall inter-rater agreement. Cohen's kappa value was used to assess repeat measurement consistency for each rater.

RESULTS

Overall inter-rater agreement using dual- and single-volume reconstruction was 0.81 and 0.75, respectively. Dual-volume reconstruction resulted in superior agreement in assessing location, occlusion status, position of aneurysm recanalization or residual, status of nearby branches, presence of coil migration and presence of intravascular devices (stent or Pipeline).

CONCLUSION

Three-dimensional reconstruction is an important complementary imaging technique in evaluating the angioarchitecture of aneurysms and recanalization after endovascular embolization. Dual-volume reconstruction imaging was associated with superior inter- and intra-rater reliability.

[Importance of preoperative and intraoperative imaging for operative strategies]

Recent advances in preoperative and postoperative imaging have an increasing influence on surgical decision-making and make more complex surgical interventions possible. This improves the possibilities for frequently occurring challenges and promoting improved functional and oncological outcome. This manuscript reviews the role of preoperative and intraoperative imaging in surgery. Various techniques are explained based on examples from hepatobiliary surgery and neurosurgery, in particular real-time procedures, such as the online use of augmented reality and in vivo fluorescence, as well as new and promising optical techniques including imaging of intrinsic signals and vibrational spectroscopy.