Size and attenuation CT (SACT) of residual masses in patients with follicular Non-Hodgkin Lymphoma: More than a status quo?

PurposeTo evaluate CT-attenuation ratio of residual masses in patients with follicular Non-Hodgkin lymphoma (FL) at end-treatment compared to baseline mass density and determine its potential prognostic relevance.Materials and methods52 consecutive patients with FL presenting with residual masses after chemotherapy receiving whole-body-CECT at baseline, end-treatment, and post-treatment were identified retrospectively by a search of our electronic medical record database from 2002 through 2010. An attenuation ratio (AR), defined as the quotient of CT-attenuation [HU] between tumor and muscle was measured. Size was recorded as the product of long- and short-axis diameter of masses. In 38/52 patients a follow-up period of ≥2 years was available to correlate results with relapse-free survival.ResultsAR and tumor size of masses significantly decreased in responders when baseline was compared to end-treatment (n = 70; p < 0.05, respectively). An increase in both, AR and size was recorded in case of relapse (n = 14; p < 0.05, respectively). 12/53 masses initially responded to therapy but relapsed within the consecutive 2-year period. The mean time to relapse was 13.5 months (range 5–24 months). AR measured at the time of end-control was significantly lower in masses remaining stable for ≥2 years (n = 41) compared to masses with relapse during 2-year follow-up (n = 12; p < 0.05). At a threshold of an AR > 1 at end-control the specificity and sensitivity for relapsing disease within 2 years reached 83% and 75%, respectively.ConclusionCT-attenuation measurements of residual masses in patients with FL at end-control may aid in the risk stratification of early (≤2 years) relapsing disease.