Magnetic resonance spectroscopy of enhancing cerebral lesions: Analysis of 78 histopathology proven cases

Objectives: To investigate the efficacy of magnetic resonance spectroscopy in differentiating various types of neoplastic and non-neoplastic enhancing cerebral lesions.

Methods: The prospective study was conducted from January 2007 to December 2009 at the Department of Radiology, Aga Khan University Hospital, Karachi. All patients with enhancing brain lesions on magnetic resonance imaging who underwent magnetic resonance spectroscopy and a biopsy with histopathological analysis were included in study. The lesions were categorised into neoplastic and non-neoplastic lesions on the basis of spectroscopy findings. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of magnetic resonance spectroscopy were calculated. Predicted probabilities were computed and comparison of median values of metabolites and their ratios was analysed using non-parametric Mann Whitney U test to differentiate between neoplastic and non-neoplastic lesions.

Results: Of the 102 patients enrolled, 78(76.5%) comprised the final study sample. There were 53(68%) male and 25(32%) female patients with an overall mean age of 40.21±17.69 years (range: 4-76 years). The mean overall size of the lesion was 4.01±1.79cm, and 61(78%) lesions were neoplastic and 17(22%) were non-neoplastic. The sensitivity, specificity, positive predictive value and negative predictive value and diagnostic accuracy of magnetic resonance spectroscopy in differentiating neoplastic and non-neoplastic lesions were 90.16%, 64.70%, 90.16%, 64.70% and 78.20% respectively. A cut-off value of 2.55 of Choline/N-Acetyl Aspartate ratio depicted sensitivity of 70% in differentiating the lesions.

Conclusion: Magnetic resonance spectroscopy is a highly sensitive technique in addition to conventional magnetic resonance imaging in characterising and differentiating between neoplastic and non-neoplastic cerebral lesions.