Quantitative diffusion weighted MRI: A functional biomarker of nodal disease in Hodgkin lymphoma?

Abstract

Purpose:

This study explores the relationship between MRI Apparent Diffusion Coefficient (ADC) and PET Standardized Uptake Value (SUV) measurements in pediatric Hodgkin lymphoma.

Methods:

Sixteen patients (mean age 15.4 yrs, 8 male) with proven Hodgkin lymphoma were recruited and staged using PET-CT, anatomical MRI and additional 1.5T diffusion weighted imaging (DWI) prior to and following chemotherapy. Pre-treatment lymph nodes and anatomically paired post-treatment residual tissue located on MRI were matched to the corresponding PET-CT. Region of interest (ROI) analysis was used to extract quantitative measurements. Mean ADC (ADC_mean) and maximum SUV (SUV_max) were recorded and correlation assessed using Spearman statistics.

Results:

Fifty-three ROIs were sampled. Pre- and post-treatment ADC_mean ranged from 0.77 × 10^-3 to 1.79 × 10^-3 (median 1.15 × 10^-3 mm²s^-1) and 1.08 × 10^-3 to 3.18 × 10^-3 (median 1.88 × 10^-3mm²s^-1), and SUV_max from 2.60 to 25.4 (median 8.85 mg/ml) and 1.00 to 3.50 mg/ml (median 1.90 mg/ml). Median post-treatment ADC_mean was higher, and median SUV_max lower than pre-treatment values (p< 0.0001). There was an inverse correlation between pre-treatment ADC_mean and SUV_max (p=0.005) and between fractional change ([post-treatment – pre-treatment]/pre-treatment) in ADC_mean and SUV_max (p=0.002).

Conclusion:

Our results confirm a strong reciprocal relationship between nodal ADC_mean and SUV_max in Hodgkin lymphoma; supporting the potential application of quantitative DWI as a functional biomarker of disease.

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