F-18 FDG versus Ga-67 for detecting splenic involvement in Hodgkin's disease

The objectives of this investigation were to characterize splenic uptake patterns of F-18 fluorodeoxyglucose (FDG) and Ga-67 in newly diagnosed Hodgkin's disease, to correlate these uptake patterns with the presence or absence of splenic disease, and to compare the accuracy of these two studies for detecting splenic disease.

FDG positron emission tomography and Ga-67 whole-body and SPECT imaging were performed in 32 patients with previously untreated Hodgkin's disease. Two readers, blinded to clinical information and final diagnoses, independently reviewed the study results. For both FDG and Ga-67, the intensity of splenic uptake was compared with the intensity of hepatic uptake and graded as follows: 0, less than liver uptake; 1, equal to liver uptake; and 2, greater than liver uptake. Differences in interpretation were resolved by consensus.

Twelve (38%) of 32 patients had splenic disease. Using splenic uptake greater than hepatic uptake as the criterion for a positive study, the sensitivity, specificity, and accuracy of FDG were 92%, 100%, and 97%, respectively. Using splenic uptake at least as intense as hepatic uptake as the criterion for a positive study, the sensitivity specificity, and accuracy of Ga-67 were 50%, 95%, and 78%, respectively. The differences in sensitivity and accuracy of FDG and Ga-67 were significant (P = 0.04, and 0.03, respectively).

In newly diagnosed Hodgkin's disease, FDG accurately diagnoses splenic involvement and is significantly more sensitive and accurate than Ga-67 for this purpose.