Magnetic Resonance Spectroscopic (MRS) Correlation of Diffusely Infiltrating Astrocytomas with Histological Grading

Open Access

Abstract

Background: Diffusely infiltrating astrocytomas are common primary brain tumors with variable histopathological grades. Accurate preoperative grading is crucial for treatment planning. Magnetic resonance spectroscopy (MRS) provides a non-invasive means to evaluate tumor metabolism, potentially aiding in grading. Objective: To evaluate the correlation between MRS findings and histological grading in diffusely infiltrating astrocytomas. Methods & Materials: This observational cross-sectional study included 30 patients diagnosed with diffusely infiltrating astrocytomas at multiple tertiary centers in Dhaka, Bangladesh, from June 2010 to April 2012. MRS parameters—choline (Cho) peak, N-acetyl aspartate (NAA) peak, creatine (Cr) peak, and Choline/Creatine (Cho/Cr) ratio—were measured preoperatively. Tumor specimens were collected during surgery for histopathological grading according to WHO criteria. Data were analyzed using SPSS, and ANOVA was used to compare metabolite peaks across tumor grades. Results: The mean age was 37.77 ± 13.16 years, with male predominance (70%). Histopathology revealed 33.3% grade II, 20% grade III, and 46.7% grade IV astrocytomas. Cho peak increased from grade II to IV, NAA decreased from grade II to III but rose in grade IV, and Cr showed variable trends. The Cho/Cr ratio progressively increased with tumor grade (Grade II: 1.997 ± 0.42; Grade III: 2.312 ± 1.07; Grade IV: 2.961 ± 1.08) and demonstrated a significant correlation with histological grade (F = 3.444, p = 0.047). No significant correlation was observed for Cho, NAA, or Cr peaks individually. Conclusion: The Cho/Cr ratio is a reliable MRS biomarker for differentiating low- and high-grade diffusely infiltrating astrocytomas. Absolute metabolite peaks alone may be insufficient due to variability and overlap. MRS can aid in preoperative tumor grading, particularly for patients unfit for surgical intervention.