Quantitative imaging biomarkers of CNS lymphoma and its correlation with genotypic markers.

Abstract

e14520 Background: Central nervous system (CNS) lymphoma can be divided into primary CNS lymphoma (PCNS) versus secondary involvement of the CNS in systemic lymphoma. Traditionally radiology-pathology correlation is needed to accurately stage these entities, but the invasive nature of intracranial biopsies can add to patient morbidity. As such, there is an unmet need for noninvasive imaging biomarkers of CNS lymphoma. We aim to assess whether quantitative imaging analysis can characterize improve diagnostic specific and identify underlying genomic alterations in CNS lymphoma. Methods: 42 cases of CNS lymphoma (26 males, 16 females) were reviewed. Inclusion criteria required MRI (1.5Tesla or 3.0Tesla) of the brain and time-concordant histopathologic evaluation (i.e. MRI obtained within 72 hours of histologic evaluation) confirming diagnosis of CNS lymphoma. 19 patients met the inclusion criteria: 16 patients with large B-cell and 3 patients with T-cell lymphoma. All diagnoses were confirmed by evaluating biopsies through morphological and immunohistochemical analysis. MRI studies included T1-weighted pre- and post-contrast images, T2-weighted images and diffusion weighted images. Quantitative analysis included 3D-volumetric and textural analysis. Results: In B-cell lymphoma, mean patient age was 57 (22-91) while in T-cell lymphoma mean age of diagnosis was 43 (20-59). On MRI, all cases of CNS lymphoma (B- and T-cell) demonstrated enhancement. All T-cell lymphoma lesions were intra-axial and demonstrated homogeneous enhancement. Meanwhile, B-cell lymphomas demonstrated variable pattern of enhancement (homogenous; reticulonodular; subcortical U-fiber; peripheral). 80% (4/5) patients tested for MYC alterations demonstrated peripheral enhancement. 70% (7/10) tested for BCL2 expression demonstrated homogenous enhancement; while BCL2 & MYC dual-expression was noted in the remaining 30% (3/10) with MRI showing peripheral enhancement. All CNS lymphomas demonstrated restricted diffusion with variable ADC range: 292-980. 84.2% (16/19) of the cases were intra-axial while 15.2 (3/19) were extra-axial (all of which were B-cell lymphoma). Conclusions: Our study shows all lymphomas enhance and demonstrate variable degree of restricted diffusion. Patients with Myc-alterations or dual-expression of BCL2-MYC showed peripheral enhancement, while isolated BCL2 expressed tumors showed homogeneous enhancement.