25. Positron Emission Tomography in Hodgkin's Disease. Correlation with Computed Tomography and Gallium 67 Citrate...

Purpose: To compare the sensitivity of F18 - FDG Positron Emission Tomography (PET), Computed Tomography (CT) and Planar Gallium 67-Citrate (GS) in the diagnosis of Hodgkin's Disease.Materials and Methods: Thirty (30) adult patients with histopathologically confirmed diagnosis of Hodgkin's Disease between Oct 97 and June 98 at KFSH & RC had the three diagnostic imaging modalities for the initial work up; in twenty eight patients for newly diagnosed and in two patients for recurrent disease. Nodular sclerosis was the histological subtype in 25 patients, mixed cellularity in 3 and lymphocytic predominance in 2.Results: For the initial evaluation of the results, a positive site by any of the three diagnostic imaging modalities was considered actual location of the disease. The patient-site sensitivity of PET, CT and for GS were 93.33%, 80% and 53.3% respectively. False negative results were observed in 2 patients with PET, 7 with CT and 14 with GS. The Spleen was the commonest site for false negative result in GS (4 patients) axilla and bones in CT (2 patients each), the 2 patients with false negative results with PET were in the lung. The difference in sensitivity between PET and GS was statistically significant (P = 0.002), but was not significant between PET and CT (P = 0.18). Although CT showed better sensitivity and accuracy when compared with GS, that didn't reach statistical significance (P = 0.09).Conclusion: PET Scan has the highest sensitivity in the initial evaluation in this small group of patients with Hodgkin Disease, especially when compared with GS. Evaluations of the final sensitivity, specificity and accuracy of these imaging modalities will be presented.