Hyperspectral and multispectral imaging in neurosurgery: a systematic literature review and meta-analysis.

INTRODUCTION: The neuro-surgical community is witnessing a rising interest for surgical application of multispectral/hyperspectral imaging. Several potential technical applications of this optical imaging are reported, but the set-up is variable and so are the processing methods. We present a systematic review of the relevant literature on the topic. MATERIALS AND METHODS: A literature search based on the PRISMA principles was performed on PubMed, SCOPUS, and Web of Science, using MESH terms and Boolean operators. Papers regarding intra-operative in-vivo application of multispectral and/or hyperspectral imaging in humans during neurosurgical procedures were included. Papers reporting technologies related to radiological applications were excluded. A meta-analysis on the performance metrics was also conducted. RESULTS: Our search string retrieved 20 papers. The main applications of optical imaging during neurosurgery concern tumour detection and improvement of the extent of resection (15 papers) or visualization of perfusion changes during neuro-oncology or neuro-vascular surgery (5 papers). All the retrieved articles were pilot studies, proof of concepts, or case reports, with limited number of patients recruited. Sensitivity, specificity, and accuracy were promising in most of the reports, but the metanalysis showed heterogeneous approaches and results among studies. CONCLUSIONS: The present review shows that several approaches are currently being tested to integrate hyperspectral imaging in neurosurgery, but most of the studies reported a limited pool of patients, with different approaches to data collection and analysis. Further studies on larger cohorts of patients are therefore desirable to fully explore the potential of this imaging technique.

Tuning Confined Nanospace for Preparation of N-doped Hollow Carbon Spheres for High Performance Supercapacitors.

The structural parameters and surface functionalities of hollow carbon spheres are critical for their electrochemical performance. Herein, preparation of N-doped-hollow carbon spheres (N-HCS) with tunable structural parameters and surface properties is reported by using a confined pyrolysis strategy. Polystyrene/polyaniline (PSPAN) was pyrolyzed in a silica shell, which provided a confined nanospace. PSPAN functioned as both the core and a source of carbon and nitrogen. The surface properties and structural parameters of the obtained N-HCS could be optimized by regulating the pore size of the silica shell. The silica shell coating also prevented agglomeration of the N-HCS, leading to a regular and well-distributed spherical morphology. The N-HCS synthesized in relatively porous conditions had thinner shell, larger mesopore size, higher surface area, and higher nitrogen content and showed excellent electrochemical performance as a supercapacitor with a specific capacitance of 436.5 F g-1 at 0.5 A g-1 .

N-Doped Hollow Carbon Spheres/Sheets Composite for Electrochemical Capacitor.

Functional carbon materials with a combination of 0 dimension and 2 dimension are particularly interesting in the electrochemical field owing to the low density, high surface area, and strong ion-bearing capacity. Especially, hollow mesoporous carbon spheres (0 dimension) and nanosheet (2 dimension) composite hollow porous carbon spheres and nanosheet (HMCS/S) have received much attention as electrochemical capacitor electrode materials. However, it is challenging for effective preparation of this complex composite structure. In this work, a novel and simple procedure to prepare N-doping HMCS/S (N-HMCS/S) is presented. This approach adopted silica spheres as the core and employed [C18Mim]Br and tetraethyl orthosilicate as the structural directing agent for the formation of the flaky/spherical hybrid structure. The unique structure of nanosheets embedded by hollow carbon spheres and N-doping characteristics endow N-HMCS/S with good performance in electrochemical capacitor with high specific capacity (196.5 F g-1) in the three-electrode system and excellent high-rate capability with retention of 61.5% in the two-electrode system.