Diagnostic Accuracy and Imaging Appearance Glioblastoma Multiforme on MRI and MRS

Abstract

Objective: To determine the diagnostic accuracy of contrast-enhanced MRI with conventional sequences and MR Spectroscopy in the diagnosis of Glioblastoma Multiforme, taking histopathology as the gold standard. We also determined the MR imaging appearance of GBM on conventional sequences.

Methodology: This descriptive cross-sectional study was conducted at a tertiary care hospital from 19^th August 2019 to 18^th August 2020 on 165 adult patients suspected of having an intracranial space-occupying lesion. Informed consent was sought and a questionnaire was filled out for patient data, MRI imaging findings, and MRS results.

Histopathology results were subsequently followed and recorded. The diagnostic accuracy of contrast enhanced MRI brain as well as MRS was determined in terms of sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy, taking histopathology as gold standard.

Results: In a total of 165 patients selected for the study, the mean age was 56.34±10.04 years with a male to female ratio of 1:1 and the frontal lobe being the most common location (34.5%). In histopathological positive GBM cases, margins of the mass were ill-defined in 55.1%, intralesional low ADC values were observed in 63.3%, signal drop out on susceptibility imaging in 42.8%, and MRS with raised choline and reduced NAA in 75.5%. MRI had a sensitivity of 81.6% and  specificity of 94.8%, and MRS has a sensitivity of 75.5% and a specificity of 100%.

Conclusion: Ill-defined margins, necrosis, and hemorrhage are important MRI features suggesting GBM. MRS combined with conventional MR sequences has high sensitivity and specificity in its diagnosis.