Fluorescence Assisted Stereotactic Biopsy of Contrast-Enhancing Brain Lesions: Can YELLOW 560-nm Filter Substitute Frozen Section?

Abstract

The factors on which the accuracy of stereotactic brain biopsy depends are the competence of the neurosurgeon in obtaining a representative sample and the ability of the neuro-pathologist to make a histological diagnosis from a minuscule sample. Over the years intraoperative frozen section has enhanced the diagnostic yield of this minimally invasive procedure. Use of fluorescence in achieving a greater extent of resection is well-established in contemporary neurosurgical practice. This ability of brain tumours to take up the fluorescein sodium dye and glow under the YELLOW 560nm filter has been utilized in a handful of studies to increase the diagnostic accuracy of stereotactic biopsy. We performed a prospective study where the fluorescein sodium dye was injected at a low dose and fluorescence of the biopsied core was compared with that of a tissue obtained from the normal parenchyma. Sample was labeled ‘truly fluorescent’ only when the glow was more than that of the tissue from normal parenchyma. On cross-tabulating the index test (true fluorescence status) and the reference standard test (final histopathological report) the sensitivity of acquiring a representative sample was found to be 94.74%, specificity was 100%. The positive predictive value (PPV) and negative predictive value (NPV) were calculated to be 100% and 50% respectively. The diagnostic yield was comparable to that of the intraoperative frozen section. The use of the YELLOW 560nm filter can make stereotactic biopsy faster, safer, less cumbersome, and more cost-effective, and can be used as a substitute for the frozen section in resource-constrained centers.