SOMATOSTATIN RECEPTOR SCINTIGRAPHY AND MAGNETIC-RESONANCE-IMAGING IN RECURRENT MEDULLARY-THYROID CARCINOMA - A COMPARATIVE-STUDY

In a prospective study, 18 patients with recurrent medullary thyroid c arcinoma (MTC) underwent magnetic resonance imaging (MRI) of the neck and mediastinum and somatostatin receptor scintigraphy (SRS) with In-1 11-labeled pentetreotide. In nine patients with macroscopic MTC, 17 co rresponding lesions were found on MRI and SRS; in addition, 13 suspici ous lesions were seen on SRS only. Histological confirmation was avail able for 19 metastatic lesions, showing MRI to be true positive in 13 metastases, SRS in 18. In minimal residual disease (n = 10), MRI and S RS were compared with the histological findings in three patients and with selective venous catheterization (SVC) in seven patients. Corresp onding findings on MRI and SVC were seen in one of seven, whereas SRS and SVC showed concordant localization of tumor recurrence in five of seven. Histological examination demonstrated MTC tissue in one of thre e cases; MRI and SRS were false positive in one of three cases, while in the others the interpretation remained uncertain. In conclusion, SR S is a promising imaging modality for localization of MTC recurrence. MRI provides better spatial resolution and thus facilitates the planni ng of surgery for macroscopic metastases. In minimal residual disease, SRS turned out to be superior in detecting occult MTC recurrence, con firming SVC findings.