P. Rigo

A residual mass after treatment of lymphoma is a clinical challenge, because it may represent vital tumor as well as tissue fibrosis. Metabolic imaging by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) offers the advantage of functional tissue characterization that is largely independent of morphologic criteria. We compared 18F-FDG PET to computed tomography (CT) in the posttreatment evaluation of 54 patients with Hodgkin's disease (HD) or intermediate/high-grade non-Hodgkin's lymphoma (NHL). Residual masses on CT were observed in 13 of 19 patients with HD and 11 of 35 patients with NHL. Five of 24 patients with residual masses on CT versus 1 of 30 patients without residual masses presented a positive 18F-FDG PET study. Relapse occurred in all 6 patients (100%) with a positive 18F-FDG PET, 5 of 19 patients (26%) with residual masses on CT but negative 18F-FDG PET, and 3 of 29 patients (10%) with negative CT scan and 18F-FDG PET studies (P </=.0001). We observed a higher relapse and death rate in patients with residual masses at CT compared with patients without residual masses at CT (progression-free survival at 1 year: 62 +/- 10 v 88 +/- 7%, P =. 0045; overall survival at 1 year: 77 +/- 5 v 95 +/- 5%, P =.0038). A positive 18F-FDG PET study was even more consistently associated with poorer survival: compared with patients with a negative 18F-FDG PET study, the 1-year progression-free survival was 0% versus 86% +/- 5% (P <.0001) and the 1-year overall survival was 50% +/- 20% versus 92% +/- 4% (P <.0001). The detection of vital tumor by 18F-FDG PET after the end of treatment has a higher predictive value for relapse than classical CT scan imaging (positive predictive value: 100% v 42%). This could help identify patients requiring intensification immediately after completion of chemotherapy. However, 18F-FDG PET mainly predicts for early progression but cannot exclude the presence of minimal residual disease, possibly leading to a later relapse.

The stroke volume ratio (SVR) is a new, non invasive method to quantify ventricular volume overload (VVO). We have analyzed its value, sensitivity and specificity in routine clinical practice. The results of 238 consecutive patients (pts) were analysed prospectively within a 3 months period. The SVR was expressed as the ratio of left ventricular (LV) stroke counts over the right ventricular (RV) stroke counts measured on the time-activity curves. One region of interest was drawn per ventricle on the phase and amplitude images. Values above 1.6 were considered as LVVO and below 0.9 as RVVO. Fifty-one patients had VVO due to valvular regurgitation or left-to-right shunt; 187 patients had no evidence of VVO. Mean value obtained for 23 normal subjects with adequate positioning was 1.27 +/- 0.14 (MV +/- SD), ranging from 0.9 to 1.47. Among patients with adequate positioning, no difference was observed in subgroups with dilated cardiopathy (DC) or anteroseptal aneurysm (AA) despite a low EF. MV for patients with LV or RV hypertrophy (H) were statistically different. Sensitivity was 82% for the 51 patients with VVO. False negatives were due to biventricular overload or mild VVO. Specificity evaluated in the 187 patients without VVO was 76%. The 45 false positives were due to poor separation of the right cardiac chambers and/or of the 2 ventricles. They were observed in 4 patients with AA, 3 patients with DC, 7 patients with LVH, 4 patients with RVH and 24 patients with inadequate positioning. No explanation was found in 3 patients. We conclude that cardiac equilibrium blood pool scintigraphy has an adequate sensitivity and specificity to evaluate patients with VVO.