Agreement rates among single photon emission computed tomography using gallium-67, computed axial tomography and lymphangiography for Hodgkin disease and correlation of image findings with clinical outcome.

BACKGROUND

This study was undertaken to systematically evaluate the agreement rates among single photon emission computed tomography using gallium-67 (Ga-67 SPECT), lymphangiography (LAG), and computed axial tomography (CT) scan findings for Hodgkin disease and to correlate radiologic findings with clinical outcome.

METHODS

One hundred three previously untreated patients with Hodgkin disease who had Ga-67 SPECT scan between August 1992 and December 1994 at our institution form the basis of this study. The agreement rates among Ga-67 SPECT, LAG, and CT scan findings were calculated by sites from the pretreatment evaluation throughout the courses of chemotherapy. The probabilities of recurrence or progression by sites were correlated with the radiologic findings.

RESULTS

The median follow-up was 3 years. The pretreatment agreement ranged from 75% to 100% between Ga-67 SPECT and CT scans, 85-100% between CT scan and LAG, and 74-99% between Ga-67 SPECT and LAG. A greater variation in agreement was observed once chemotherapy was started, the site with the least agreement being the mediastinum. The most common site of the recurrence or progression was also the mediastinum. When the CT scan showed persistent abnormality even after Ga-67 SPECT turned negative after chemotherapy, the chances of mediastinal recurrence or progression were 3 in 34 and 3 in 18 after 1-3 cycles and 4-6 cycles, respectively.

CONCLUSIONS

Although there was a relatively high correlation between Ga-67 SPECT and the other modalities, the intrinsic limitation of planar Ga-67 was still observed in Ga-67 SPECT especially in the mediastinum. There was still a moderate risk of mediastinal recurrence or progression even after residual CT scan abnormality lost gallium avidity from chemotherapy.