MONITORING BULKY MEDIASTINAL DISEASE WITH GA-67, CT-SCAN AND MAGNETIC-RESONANCE-IMAGING IN HODGKINS-DISEASE AND HIGH-GRADE NON-HODGKINS-LYMPHOMA

Treatment of both Hodgkin's disease (HD) and high-grade non-Hodgkin's lymphoma (HG-NHL) with bulky presentation at diagnosis frequently resu lts in residual masses detected radiologically. Conventional diagnosti c radiology and computed tomography (CT) are generally unable to detec t the differences between tumor tissue and fibrosis. Gallium-67-citrat e (Ga-67) SPECT and magnetic resonance imaging (MRI) can potentially d ifferentiate residual active tumor tissue and fibrosis. Thirty-three p atients with HD or HG-NHL presenting with bulky mediastinal disease we re studied with CT, Ga-67 SPECT, and MRI (only for 16 patients) at dia gnosis, after two-thirds of their chemotherapy, at the end of chemothe rapy, and after radiotherapy in order to evaluate the mediastinal regi on on the basis of persistence of residual masses and activity of path ological tissue. After treatment, all patients with Ga-67-negative (30 /33) disease are still in continuous complete response. Among the thre e Ga-67-positive patients, 2 relapsed within one year and another one is still alive without evidence of disease. Regarding MRI, two patient s were found to be positive, one of them concomitant with Ga-67-positi vity; both patients survive in complete response. In lymphoma patients with bulky mediastinal presentation, the Ga-67 SPECT remains the pref erable imaging technique for monitoring and differentiating the eventu al active residual tumor. In combination, CT and Ga-67 SPECT represent a suitable complete imaging approach to the radiological diagnosis wh ich may be useful in these particular patients. MRI could probably be considered as a second-line method and from our data would be used onl y in selected cases because of the high cost, accessibility, and lower specificity as opposed to Ga-67 SPECT in evaluating potentially activ e residual disease.