Naveen J.1 , Arul T. Dasan2 , Chandrashekar H. M.3 , Samarth Somashekara Gowda4 , Jyothi G. Dulli5
BACKGROUND The central nervous system is a common site of tumorigenesis, where gliomas constitute ~80% of primary malignant brain neoplasms. CNS neoplasms are first classified into specific tumour types and then further graded as a measure of malignancy. We wanted to evaluate the diffusion characteristics in high - and low - grade gliomas and correlate the ADC values of brain gliomas with the WHO histopathological grades. METHODS The study group included 35 patients during the period of June 2017 to July 2018, who had histopathologically proven gliomas of varying grades. The MRI images of the patients (performed using a Siemens Magnetom Avanto 1.5T MRI machine at Victoria Hospital, Bangalore Medical College and Research Institute, Bangalore) were reviewed retrospectively. MRI detected cases of Gliomas without HPE reports and patients with postoperative recurrent tumours, were excluded from the study group. RESULTS The most common age group was found to be 40 to 59 years, with a distinct male predilection. MR images revealed diffusion restriction in cases of glioma, differing only in the amount of restriction as assessed by the corresponding mean and minimum ADC values. It was noted that the mean and minimum ADC values were relatively higher for cases of low grade gliomas, when compared to that obtained from high grade gliomas. The average minimum ADC values were 1.11 (grade I tumour), 0.96 (grade II tumour), 0.92 (grade III tumour) and 0.74 (grade IV tumour). The average mean ADC values were 1.19 (grade I tumour), 1.05 (grade II tumour), 0.98 (grade III tumour) and 0.86 (grade IV tumour). Statistical significance was found between the calculated ADC values and the histopathological tumour grade (p value was <0.001 for both values). CONCLUSIONS Our study confirmed that diffusion weighted MR imaging with ADC (both mean and minimum) value measurements, can be used to differentiate high - and low - grade gliomas in a non-invasive method for approximating tumour grade. We demonstrated that as the tumour cellularity and the grade increases, both the mean and minimum ADC values decrease.
