Evaluation of Brain Tumours using Magnetic Resonance Perfusion Imaging: A Prospective Study

Abstract

Introduction: Brain tumours are an important cause of neurological problems. Grade of these tumours is one of the parameters which decide the treatment offered to patients. Magnetic Resonance Imaging (MRI) though superior to other conventional modalities still has few limitations in assessing grade of tumours. Perfusion MRI by virtue of its ability to measure haemodynamic parameters can be used to access grade of tumour. Aim: To evaluate the role of perfusion MRI in evaluation of brain tumours by using relative Cerebral Blood Volume (rCBV). Materials and Methods: A prospective study was carried out in a tertiary care hospital from July 2015 to June 2018. MRI was performed on 23 patients using conventional imaging, perfusion imaging with T2*-weighted Echo-Planar sequence after administration of Gadopentetate dimeglumine. Perfusion data was processed to obtain colour maps and rCBV value was generated. rCBV values were correlated with histopathological grade of tumours. Statistical analysis was done by using SPSS (Statistical Package for Social Sciences) Version 20.0. Tukey’s test was used to compare the mean rCBV value for pairwise comparison of grades of tumour and unpaired t-test was used to compare the mean rCBV between high grade and low grade astrocytomas. Receiver’s Operating Characteristics (ROC) curve was used to find the sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) and cut-off value of rCBV for detection of high grade tumour. Results: Grade I astrocytoma and Grade II astrocytoma had mean rCBV of 1.435±1.063 and 2.046±1.282, respectively. Grade III astrocytoma and Grade IV astrocytoma had mean rCBV of 7.620±3.463 and 12.455±0.361 respectively. Mean rCBV of medulloblastoma was 4.185±2.482. Low grade astrocytoma (grade I and grade II) had mean rCBV of 1.817±1.207 and high grade astrocytoma (grade III and grade IV) had mean rCBV of 9.554±3.611. There was significant difference between mean rCBV in Grade I/II vs III/IV (p<0.001), there was no significant difference between mean rCBV in Grade I and Grade II. Conclusion: Perfusion MRI is useful in differentiating low grade (grade I and II) astrocytoma from high grade (grade III and IV) astrocytoma.

Keywords

• astrocytoma
• magnetic resonance imaging
• relative cerebral blood volume