The role of diffusion-weighted magnetic resonance imaging in the evaluation of brain mass lesions

Abstract

Context: The purpose of this study was to assess the role of diffusion-weighted-magnetic resonance imaging (DW-MRI) and apparent diffusion coefficient (ADC) values in the evaluation of different benign and malignant brain mass lesions with histopathological correlation. Aims: To assess the role of DW-MRI in the evaluation of different mass lesions of the brain with histopathological correlation. To evaluate the role of ADC values in characterization and differentiation of benign and malignant mass lesions of the brain. Settings and Design: The study design was a cross-sectional study and it was done in patients who were referred to Victoria Hospital attached to Bangalore Medical College and Research Institute (BMC and RI), Bengaluru between December 2012 and November 2014. The sample size of the study was 50. Subjects and Methods: We retrospectively reviewed 50 MR examinations of patients who were referred to Department of Radio Diagnosis, BMC, and RI, Bengaluru for intracranial mass lesion evaluation with MRI. All of them had undergone conventional MRI examination with Siemens AVANTO 1.5T scanner, and we determined ADC values and signal intensities on DW images (DWIs). In all patients with contrast-enhanced tumors, region of interests (ROIs) were placed in the enhanced region. In patients with nonenhancing tumors, ROIs were placed in the solid part of the lesion. We also evaluated the correlation between ADC values and cellularity in the mass lesions. Additional clinical details and histopathological findings were correlated with the DWI and ADC findings for radiologic-pathologic concordance. Statistical Analysis: Brain MRI results of 50 patients with histologically verified or clinically diagnosed brain mass lesions were subjected to analysis. They ranged in age from 2 to 72 years (mean, 43.5 years). The examinations were performed with a 1.5T scanner, an 8-channel surface head coil. The examination protocol included the following sequences and images: Turbo spin-echo (SE) T2-weighted images (3920/102/1), fluid-attenuated inversion recovery (2500/9000/111/1) ([inversion time/repetition time (TR)/echo time (TE)/excitations], and SE T1-weighted images [488/10/1] [TR/TE/excitations]), carried out in three planes, before and after contrast medium administration (in a standard dose). Results: A positive correlation was found in the comparison of mean ADC values for high-grade gliomas (1.19 × 10−3 mm 2 /s ± 0.2) and metastasis (0.833 × 10−3 mm 2 /s ± 0.2), low-grade gliomas (1.34 × 10−3 mm 2 /s ± 0.2), and medulloblastomas (0.68 × 10−3 mm΂/s ± 0.075), as well as for in epidermoid cyst and necrotic areas in malignant tumors. Conclusion: ADC is useful in the differentiation of various brain mass lesions, in grading brain tumors, and differentiation of benign cystic and malignant necrotic areas. The combination of routine image interpretation and ADC had a higher predictive value. The ADCs of glioma, metastasis, and meningioma are related to tumor cellularity. We believe that DWIs and ADCs can provide information useful to diagnose brain mass lesions that cannot be obtained with conventional MRI alone.