Toward digital histopathological assessment in surgery for central nervous system tumors using stimulated Raman histology.

OBJECTIVE: Intraoperative neuropathological assessment with conventional frozen sections supports the neurosurgeon in optimizing the surgical strategy. However, preparation and review of frozen sections can take as long as 45 minutes. Stimulated Raman histology (SRH) was introduced as a novel technique to provide rapid high-resolution digital images of unprocessed tissue samples directly in the operating room that are comparable to conventional histopathological images. Additionally, SRH images are simultaneously and easily accessible for neuropathological judgment. Recently, the first study showed promising results regarding the accuracy and feasibility of SRH compared with conventional histopathology. Thus, the aim of this study was to compare SRH with conventional H&E images and frozen sections in a large cohort of patients with different suspected central nervous system (CNS) tumors. METHODS: The authors included patients who underwent resection or stereotactic biopsy of suspected CNS neoplasm, including brain and spinal tumors. Intraoperatively, tissue samples were safely collected and SRH analysis was performed directly in the operating room. To enable optimal comparison of SRH with H&E images and frozen sections, the authors created a digital databank that included images obtained with all 3 imaging modalities. Subsequently, 2 neuropathologists investigated the diagnostic accuracy, tumor cellularity, and presence of diagnostic histopathological characteristics (score 0 [not present] through 3 [excellent]) determined with SRH images and compared these data to those of H&E images and frozen sections, if available. RESULTS: In total, 94 patients with various suspected CNS tumors were included, and the application of SRH directly in the operating room was feasible in all cases. The diagnostic accuracy based on SRH images was 99% when compared with the final histopathological diagnosis based on H&E images. Additionally, the same histopathological diagnosis was established in all SRH images (100%) when compared with that of the corresponding frozen sections. Moreover, the authors found a statistically significant correlation in tumor cellularity between SRH images and corresponding H&E images (p < 0.0005 and R = 0.867, Pearson correlation coefficient). Finally, excellent (score 3) or good (2) accordance between diagnostic histopathological characteristics and H&E images was present in 95% of cases. CONCLUSIONS: The results of this retrospective analysis demonstrate the near-perfect diagnostic accuracy and capability of visualizing relevant histopathological characteristics with SRH compared with conventional H&E staining and frozen sections. Therefore, digital SRH histopathology seems especially useful for rapid intraoperative investigation to confirm the presence of diagnostic tumor tissue and the precise tumor entity, as well as to rapidly analyze multiple tissue biopsies from the suspected tumor margin. A real-time analysis comparing SRH images and conventional histological images at the time of surgery should be performed as the next step in future studies.

Development and assessment of competency-based neurotrauma course curriculum for international neurosurgery residents and neurosurgeons.

OBJECTIVE: Traumatic brain injuries (TBIs) are a significant disease burden worldwide. It is imperative to improve neurosurgeons' training during and after their medical residency with appropriate neurotrauma competencies. Unfortunately, the development of these competencies during neurosurgeons' careers and in daily practice is very heterogeneous. This article aimed to describe the development and evaluation of a competency-based international course curriculum designed to address a broad spectrum of needs for taking care of patients with neurotrauma with basic and advanced interventions in different scenarios around the world. METHODS: A committee of 5 academic neurosurgeons was involved in the task of building this course curriculum. The process started with the identification of the problems to be addressed and the subsequent performance needed. After this, competencies were defined. In the final phase, educational activities were designed to achieve the intended learning outcomes. In the end, the entire process resulted in competency and outcomes-based education strategy, including a definition of all learning activities and learning outcomes (curriculum), that can be integrated with a faculty development process, including training. Further development was completed by 4 additional academic neurosurgeons supported by a curriculum developer specialist and a project manager. After the development of the course curriculum, template programs were developed with core and optional content defined for implementation and evaluation. RESULTS: The content of the course curriculum is divided into essentials and advanced concepts and interventions in neurotrauma care. A mixed sample of 1583 neurosurgeons and neurosurgery residents attending 36 continuing medical education activities in 30 different cities around the world evaluated the course. The average satisfaction was 97%. The average usefulness score was 4.2, according to the Likert scale. CONCLUSIONS: An international competency-based course curriculum is an option for creating a well-accepted neurotrauma educational process designed to address a broad spectrum of needs that a neurotrauma practitioner faces during the basic and advanced care of patients in different regions of the world. This process may also be applied to other areas of the neurosurgical knowledge spectrum. Moreover, this process allows worldwide standardization of knowledge requirements and competencies, such that training may be better benchmarked between countries regardless of their income level.

Angioarchitectural heterogeneity in human glioblastoma multiforme: a fractal-based histopathological assessment.

There is currently no standard technique to objectively quantify the microvascularization of brain tumors. Fractal analysis has been proposed as a useful descriptor of tumor microvascularity. Standardization of the fractal analysis methodology could offer a new tool for this type of characterization. In this study, we applied fractal analysis to the characterization of the different angioarchitectures found in specimens of glioblastoma multiforme (GBM), the most common and most malignant type of human brain tumor. A retrospective series of 114 primary GBM specimens was carried out. To quantify neoplastic microvascularity, the level of two-dimensional geometrical complexity of the microvascular patterns was assessed using the box-counting algorithm, which estimates the microvascular fractal dimension (mvFD). mvFD makes information on the non-Euclidean space filled by vessels embedded in the tumor microenvironment available because it depends on vessel number, shape, magnitude and distribution pattern. A mean mvFD value of 1.44 ± 0.17 (range: 1.06-1.87) was found. The coefficient of variation was 44%. The high geometric variability, found objectively, in these samples reflects the angioarchitectural heterogeneity underlying GBM. The present study shows that angioarchitectural subtypes can be identified by mvFD, making this parameter a potential tool for quantifying different neoplastic microvascular patterns.

[Functional assessment before and after interventions on the optic chiasm system]. / Funktionelle Befunde vor und nach Eingriffen am optochiasmalen System.

OBJECTIVES: In the course of a tumor in the area of the optic chiasm the optochiasmal system is often exposed to compressive and vascular irritations. This study deals with the functional results (visual acuity and visual field) before and after surgery based on the primary situation and morphology of the tumor in order to give a prognosis on this matter. METHODS: 62 patients (41 female, 21 male) suffering from tumors in the area of the optic chiasm were retrospectively reviewed. The duration of the follow-up was an average of 25.82 months, +/- 20.04. Among the tumors investigated there were 36 pituitary adenomas, 20 meningiomas, 4 craniopharyngiomas, one histiozytosis X and one gangliozytoma. For visual field examination the Humphrey Field Analyzer, program 30-2, was used. 34 tumors (54.8%) were excised by the transsphenoidal approach, 28 patients (45.2%) underwent transcranial surgery. RESULTS: As for visual acuity, of the 124 eyes 53 eyes (42.8%) improved after surgery, 64 eyes (51.6%) remained unchanged, 7 eyes (5.6%) deteriorated. Of the patients who underwent transsphenoidal surgery, 28 eyes (41.2%) improved after operation, 36 eyes (52.9%) remained unchanged, and 4 eyes (5.9%) worsened. In case of transcranial surgery, 25 eyes (44.6%) improved, 28 eyes (50.0%) remained unchanged, whereas 3 eyes (5.4%) worsened. There was a postoperative improvement in 53.2% of the visual fields, 37.1% remained unchanged, whereas 9.7% deteriorated. CONCLUSION: Both the transsphenoidal and transcranial approaches showed excellent visual outcome. Our experience indicates an excellent prognosis for improvement of visual acuity and visual fields provided an adequate procedure. Results depend, however, on the primary functional and morphological situation. In the case of a large supra-/parasellar tumor component a postoperative deterioration of vision may occur.