Diffusion-Weighted MR Imaging Derived Apparent Diffusion Coefficient Is Predictive of Clinical Outcome in Primary Central Nervous System Lymphoma

Abstract

BACKGROUND AND PURPOSE There is evidence that increased tumor cellular density within diagnostic specimens of primary central nervous system lymphoma (PCNSL) may have significant prognostic implications. Because cellular density may influence measurements of apparent diffusion coefficient (ADC) by using diffusion-weighted MR imaging (DWI), we hypothesized that ADC measured from contrast-enhancing regions might correlate with clinical outcome in patients with PCNSL. MATERIALS AND METHODS PCNSL tumors from 18 immunocompetent patients, treated uniformly with methotrexate-based chemotherapy, were studied with pretherapeutic DWI. Enhancing lesions were diagnosed by pathologic analysis as high-grade B-cell lymphomas. Regions of interest were placed around all enhancing lesions allowing calculation of mean, 25th percentile (ADC25%), and minimum ADC values. Histopathologic tumor cellularity was quantitatively measured in all patients. High and low ADC groups were stratified by the median ADC value of the cohort. The Welch t test assessed differences between groups. The Pearson correlation examined relationships between ADC measurements and tumor cellular density. Single and multivariable survival analysis was performed. RESULTS We detected significant intra- and intertumor heterogeneity in ADC measurements. An inverse correlation between cellular density and ADC measurements was observed (P < .05). ADC25% measurements less than the median value of 692 (low ADC group) were associated with significantly shorter progression-free and overall survival. Patients with improved clinical outcome were noted to exhibit a significant decrease in ADC measurements following high-dose methotrexate chemotherapy. CONCLUSIONS Our study provides evidence that ADC measurements within contrast-enhancing regions of PCNSL tumors may provide noninvasive insight into clinical outcome.

Central Nervous System Lymphoma: Characteristic Findings on Traditional and Advanced Imaging

“…40,46,47 A recent study showed that pretherapeutic ADC tumor measurements within contrast-enhancing regions were predictive of clinical outcome in patients with PCNSL. 48 Low ADC values were predictive of shorter progression-free survival and overall survival. In addition, an inverse correlation was found between ADC values and the cellular density of the tumors.…”

“…Patients with prolonged progression-free survival and overall survival also had a significant reduction in post-therapeutic ADC values. 48 Thus, repeated ADC measurements may be used as biomarkers in the surveillance of therapeutic response.…”

MRI findings in primary brain lymphoma in immunocompetent patients

“…The pre therapeutic tumor apparent diffusion coefficient (ADC) measurements may noninvasively predict clinical outcome in patients with primary lymphoma of CNS. 5 Low ADC values were predictive of shorter progression-free survival and overall survival. In addition, an inverse correlation was found between ADC values and the cellular density of the tumors.…”

“Dazed and diffused”: making sense of diffusion abnormalities in neurologic pathologies

“…First, as described above, quantitative analysis of ADC values may help differentiate primary CNS lymphomas from gliomas. Additionally, a recent study found that the ADC values of untreated primary CNS lymphoma lesions may help distinguish patients who may require whole-brain radiation and prolonged chemotherapy from patients who can simply be followed after a standard chemotherapy regimen [60]. ADC values have also shown promise in distinguishing primary CNS lymphoma from toxoplasmosis in immunocompromised patients.…”