Gallium-67-citrate imaging in extragonadal and gonadal seminomas: relationship to radiologic findings.

METHODS

The results and analysis of baseline and follow-up 67Ga imaging in three patients with extragonadal seminoma were compared to those of nine patients with primary and metastatic gonadal seminomas. Gallium-67 tumor avidity was scored (0-6) relative to accumulation in the sternum and the liver. Response time to systemic therapy for 67Ga imaging compared to other radiological examinations was also measured.

RESULTS

Prior to therapy, 67Ga scan sensitivity was 100%, (3/3) in patients with extragonadal seminomas and 90%, (9/10) for primary and radiologically evident metastatic sites in patients with gonadal seminomas. The combined sensitivity was 92%, (12/13) with the smallest 67Ga scan detecting a mass 1.5 cm in diameter. There was no significant difference in 67Ga avidity or sensitivity between extragonadal and gonadal sites. Following chemotherapy, CT scanning demonstrated residual radiologic abnormalities in all three extragonadal seminoma tumor sites and 5/8 metastatic gonadal seminoma tumor sites. However, the 67Ga scan was normal in 10/11 sites at the first radionuclide examination after systemic therapy, indicating no active tumor, an observation supported by clinical follow-up from 6 to 72 mo.

CONCLUSION

Gallium-67 scanning appears useful in the management of patients with both extragonadal and gonadal seminoma and may be useful in differentiating active disease from fibrosis in the treated patient with a post-therapy residual radiologic mass.