The role of combined imaging in metastatic medullary thyroid carcinoma: 111In-DTPA-octreotide and 131I/123I-MIBG as predictors for radionuclide therapy

Abstract

Purpose: The medical treatment of metastatic medullary thyroid carcinoma (MTC) is still questionable. The aim of this study was to evaluate a combined imaging protocol using 111In-DTPA-octreotide and 131I/123I-MIBG to decide whether targeted radiotherapy would be useful, and which radiopharmaceutical (90Y-DOTATOC or 131I-MIBG) would be more effective.

Methods: Eight patients (four men, four women; mean age 61 years) with metastatic MTC were included. Treatments were performed with 3,330 MBq 90Y-DOTATOC at 6-week intervals, or 11.1 GBq 131I-MIBG with a minimum interval of 3 months.

Results: The imaging procedure was positive in all eight patients: 111In-DTPA-octreotide imaging in five patients, 131I/123I-MIBG imaging in four patients. With respect to the number of metastatic lesions, MIBG imaging was less effective than octreotide. According to the results of combined imaging, we identified one patient to be treated with 90Y-DOTATOC, and three patients with 131I-MIBG. An overall antitumor effect was observed in all four patients, one with partial remission and three with stable disease. No relevant toxicity was observed.

Conclusions: The combined imaging can increase the detection rate of metastatic foci in patients with MTC and identify more patients for effective radionuclide treatment. The treatment with 90Y-DOTATOC or 131I-MIBG is well tolerated and may improve the fate of patients with metastatic MTC.

Fig. 1A,B

¹³¹I-MIBG, anterior scintigraphy of the lung in a 65-year-old woman with metastatic MTC; pre-treatment A and post-treatment B scans demonstrate the effect of the first MIBG therapy (reduced number of foci and tracer accumulation of the metastatic lesions)

Fig. 2

Changes of calcitonin levels of the same patient as in Fig. 1 during the three treatment cycles (reference range: less than 10 pg/ml). The arrow points at the time of treatment

Fig. 3A,B

¹¹¹In-DTPA-octreotide anterior scintigraphy of the lung in a 58-y-old man with metastatic MTC; pre-treatment A and post-treatment B with ⁹⁰Y-DOTATOC, reveals that the number of lesions and tracer accumulation in the metastatic lesion are mainly unchanged

Fig. 4

Changes of calcitonin levels of the same patient as in Fig. 3 during the four treatment cycles (reference range: less than 10 pg/ml). The arrow points at the time of treatment