Cellular Density Evaluation for Malignant Lymphoma Using Equivalent Cross-Relaxation Rate Imaging - Initial Experience

Objective: Equivalent cross-relaxation rate (ECR) imaging is an MRI technique used to evaluate quantitatively a change in the protein-water interaction. We aimed to evaluate retrospectively the usefulness of ECR imaging for the histologic classification of malignant lymphoma (ML). Materials and Methods: Institutional Review Board approval was obtained and all patients provided informed consent. The study subjects included 15 patients with untreated ML who were histologically diagnosed with follicular lymphoma (FL; n = 8) or diffuse large B-cell lymphoma (DLBCL; n = 7). All patients underwent ECR imaging and the offset frequency was set at 7 ppm. Results: The median ECR values were 71% (range; 60.7 to 75.5) in FL and 54% (50.8 to 59.4) in DLBCL (p = 0.001). The median cellular density was $1.5{\pm}0.17{\times}10^6/mm^2$ in FL and $1.0{\pm}0.70{\times}10^6/mm^2$ in DLBCL (p = 0.001). The correlation coefficient between the ECR values and cellular density in ML was 0.88 (p = 0.001). In FL and DLBCL, assuming ECR value cut-off points of 60%, both sensitivity and specificity were 100%. Conclusion: A strong correlation between ECR and cellular density in ML is demonstrated and the ECR may be a useful technique to differentiate between FL and DLBCL.