Comparison of 123I-MIBG SPECT-CT and 18F-DOPA PET-CT in the evaluation of patients with known or suspected recurrent paraganglioma.

OBJECTIVES

Detection of recurrent disease is essential for treatment planning in patients with paraganglioma. The aim of this study was to compare 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphy [whole-body and single-photon emission computed tomography (SPECT) computed tomography (CT) scanning] and fluorine-18-L-dihydroxyphenylalanine positron emission tomography CT (18F-DOPA PET-CT) in the re-staging of patients with known or suspected recurrent paraganglioma.

METHODS

Twelve patients with known or suspected recurrent paraganglioma after initial surgery were included in the study. 18F-DOPA PET-CT and 123I-MIBG scintigraphy (whole-body and SPECT-CT scanning) were performed in all patients; the results were compared on a per patient and a per lesion basis. Cytohistology (when available) and a combination of laboratory and imaging studies and follow-up were used as reference standard; any modification in treatment planning was recorded. In all cases recurrent disease (local or distant) was confirmed by cytohistology (four cases) or at subsequent follow-up (eight cases).

RESULTS

All patients had positive 18F-DOPA studies (100% sensitivity) whereas nine had positive 123I-MIBG studies (75% sensitivity; P=not significant). 18F-DOPA detected 98% of lesions, whereas 38% were detected with 123I-MIBG (P=0.04). 18F-DOPA showed more lesions than 123I-MIBG in eight patients; both techniques showed the same number of lesions in two cases whereas in two patients 123I-MIBG showed a greater number of lesions. A change in treatment planning was suggested by 18F-DOPA in one patient.

CONCLUSION

These data support the superiority of 18F-DOPA PET-CT over 123I-MIBG scintigraphy to assess disease extension in patients with recurrent paraganglioma; however, in cases with inoperable disease, 123I-MIBG maintains a unique role in allowing the selection of patients suitable for 123I-MIBG therapy.