Ur Metser MD, Presenter: Nothing to Disclose

Grainne Mairead Murphy MBBCh, MMedSc, Abstract Co-Author: Nothing to Disclose

Ravi Michael Mohan MD, DPhil, Abstract Co-Author: Nothing to Disclose

Vaughan Beckley, Abstract Co-Author: Nothing to Disclose

David Christopher Hodgson MD, MPH, Abstract Co-Author: Nothing to Disclose

Based on the International Harmonization Project (IHP) criteria, PET response assessment of residual nodal masses in patients with lymphoma after completion of therapy is performed visually using mediastinal blood pool (MBP) as the reference. The purpose of this study was to define the optimal reference for PET response assessment and to determine whether visual inspection or semiquantiative measures are the preferred method of assessment.  

The study included 137 patients (age range: 18-94 years; median: 50), with Hodgkin’s (n=43) or non-Hodgkin’s lymphoma (n=94) assessed for residual masses after completion of therapy. Two experienced readers independently assessed response by IHP criteria, and on a separate read used Deauville-adapted scoring system with liver as reference for residual disease. Pathology and clinical and imaging surveillance data (mean: 19 months) was used as standard of reference. Inter-reader agreement and performance of visual versus semiquantitative analysis was performed. Comparison between methods was performed using McNemar test, with a p-value <0.05 considered significant. Kappa coefficients assessed level of agreement between readers.  

Based on the standard of reference, 36 patients (26.3%) had residual lymphoma, while 101 patients (73.7%) had complete response. For IHP and Deauville-adapted criteria, sensitivity was 97.2% (p=1), specificity was 79.2% & 92.1% (p<0.001), and overall accuracy was 83.9% & 93.4% (p=0.001), respectively; with strong interobserver agreement for both methods (Kappa = 0.858 & 0.854, respectively). For both, visual assessment performed better than uptaked-based analysis with overall accuracy of visual and SUV-based analysis was 85.4% & 68.2% for MBP (p<0.001) and 93.8% & 89.8% (p=0.039) for liver.  

Using liver rather than mediastinal blood pool as standard of reference for response assessment of patients with aggressive lymphoma and residual masses at end of therapy maintains high sensitivity for detection of residual disease and improves specificity and overall accuracy. Visual assessment outperforms semiquantitative analysis.  

IHP criteria for response assessment of patients with lymphoma and residual masses at end of therapy has yet to be validated.  Results from current study suggest that using liver rather than MBP impvoes specificity and overall accuracy.   

Metser, U, Murphy, G, Mohan, R, Beckley, V, Hodgson, D, FDG-PET/CT Response Assessment Criteria for Hodgkin’s and Aggressive Non-Hodgkin’s Lymphoma at Completion of Therapy.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14012767.html