The value of mr spectroscopy and mr perfusion in the diagnosis and grading of intracranial tumors

The grade of a tumor reflects the degree of its malignancy and is used to estimate the biological behavior of the tumor. In clinical practice, the grade of a tumor is essential in choosing the right treatment. Imaging is important for early diagnosis and correct grading. In this study, we aimed to evaluate the efficacy of magnetic resonance spectroscopy (MRS) and magnetic resonance perfusion imaging in differentiation of low grade and high grade brain tumors. Patients who were referred to our department with suspected brain tumor and had cranial MR imaging as well as MR spectroscopy and/or perfusion MRI performed between January 2012-January 2014 were included in the study. Post-op patients, patients with a history of cranial radiotherapy, patients with extra-axial tumors and patients with metastases were excluded. Images of 78 patients were retrospectively evaluated. 45 patients (57.7%) were male, 33 (42.3%) were female. The ages were between 9 and 78 (Mean 49.2±16.5). Cho/NAA, Cho/Cr and rCBV ratios were measured. Cut-off values for each parameter was calculated with ROC analysis. The sensitivity and specificity of Cho/Cr and rCBV ratios were calculated according to these cut-off values. Cho/NAA, Cho/Cr and rCBV ratios differed between low grade and high grade tumors. Area under curve as calculated with ROC analysis was 0,663 [0,507-0,819], 0,738 [0,578-0,898] and 0,852 [0,729-0,976] for Cho/NAA, Cho/Cr and rCBV respectively. Cut-off value for Cho/Cr was 2.03 (Sensitivity 75.7%, specificity 84.6%) and for rCBV ratio the cut-off was 3,63 (Sensitivity 83.8%, specificity 76.9%). When cases where both measurements were greater than the cut-off values were considered high grade and cases where both measurements were below the cut-off values were considered low-grade, the sensitivity was 89.3%, the specificity was 100%, positive predictive value was 100% and negative predictive value was 72.2%. MR spectroscopy and MR perfusion findings complement each other for the purpose of differentiation of low grade and high grade brain tumors and both modalities provide valuable information. The use of these modalities in combination result especially in increased specificity, therefore we think the use of MR perfusion and MR spectroscopy together may be more beneficial. Key words: MR perfusion, MR spectroscopy, glial tumors, brain tumors, grade