Size and attenuation CT (SACT) of residual masses in patients with follicular non-Hodgkin lymphoma: more than a status quo?

PURPOSE: To 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 METHODS: 52 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. RESULTS: AR 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. CONCLUSION: CT-attenuation measurements of residual masses in patients with FL at end-control may aid in the risk stratification of early (≤ 2 years) relapsing disease.

Volume and attenuation computed tomography measurements for interim evaluation of Hodgkin and follicular lymphoma as an additional surrogate parameter for more confident response monitoring: a pilot study.

PURPOSE: To retrospectively determine the potential role of additional computed tomography (CT) attenuation measurements for interim response evaluation in residual masses of patients with Hodgkin disease (HD) and follicular non-Hodgkin lymphoma (NHL). MATERIALS AND METHODS: In this retrospective study, 39 patients with HD and 35 patients with NHL presented with residual masses at mid-treatment CT (after 2-4 cycles of chemotherapy) and were assessed via contrast-enhanced CT at baseline, mid-treatment and post-treatment. Volume was recorded as whole-tumour volume. A tumour attenuation ratio (TAR) was calculated as the quotient of attenuation between tumour and muscle at the respective point in time versus baseline. The standard deviation of attenuation values within the tumour volume was recorded to estimate tumour heterogeneity. Results were correlated with relapse-free survival determined at a minimum of 12 months after end-treatment CT. RESULTS: Tumour volume and TAR at interim versus baseline control were significantly reduced in responders compared with non-responders, even after controlling for age, stage, treatment regimen, and baseline tumour volume. No significant differences with respect to the standard deviation of attenuation values within the tumour volumes (tumour heterogeneity) were observed. The volume and attenuation CT (VACT) criteria yielded the highest sensitivities and specificities for the identification of non-response at a threshold of a >20% increase in volume and an increase in TAR at interim control, i.e. 88% (NHL 80%, HD 100%) and 98% (NHL 97%, HD 100%), respectively. The negative predictive values reached by VACT analysis were >=97%, according to both parameters. CONCLUSION: Mid-treatment response assessment of residual masses in patients with HD and NHL using VACT may aid in the risk stratification as an additional surrogate parameter.