ADC histogram analysis of muscle lymphoma - Correlation with histopathology in a rare entity.

Objective: Diffusion-weighted imaging is able to reflect histopathology architecture. A novel imaging approach, namely histogram analysis, is used to further characterize lesion on MRI. To correlate histogram parameters derived from apparent diffusion coefficient (ADC) maps with histopathology parameters in muscle lymphoma. Methods: Eight patients (mean age 64.8 years, range 45-72 years) with histopathologically confirmed muscle lymphoma were retrospectively identified. Cell count, total nucleic and average nucleic areas were estimated using ImageJ. Additionally, Ki67-index was calculated. Diffusion-weighted imaging was obtained on a 1.5 T scanner by using the b-values of 0 and 1000 s mm(-2). Histogram analysis was performed as a whole lesion measurement by using a custom-made Matlab-based application. Results: All ADC parameters showed a good to excellent interreader variability. Cell count correlated well with ADCmean (p = -0.76, p = 0.03) and ADCp75 (p =-0.79, p = 0.02). Kurtosis and entropy correlated with average nucleic area (p = -0.81, p = 0.02, p = 0.88, p = 0.007, respectively). None of the analyzed ADC parameters correlated with total nucleic area and with Ki67-index. Conclusion: ADC histogram analysis parameters can reflect cellularity in muscle lymphoma. Advances in knowledge: Histogram parameters derived from ADC maps can reflect several different cellularity parameters in muscle lymphoma.