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Current concepts for the treatment of somatostatin receptor positive tumours have not been very motivating up to now. A promising alternative could be the new peptidic vector DOTA-D-Phe1-Tyr3-Octreotide (DOTATOC) recently developed in Basel. It may be labelled with the beta-emitter yttrium-90 (90Y) for internal radiotherapy after systemic application. Pilot therapy studies have shown convincing results with this new radiopharmaceutical. These studies are presented with regard to efficacy and possible toxicity. In summary, the new receptor-mediated 90Y-DOTATOC therapy led to tumour response in the majority of patients, and only in some receiving high cumulative doses of > 200 mCi per m2 body surface renal and hematological toxicity due to irradiation occurred. For the reduction of renal accretion, concepts with concomitant amino acid infusions containing L-lysine in a higher concentration are currently under way.

Aim: Recent in-vitro and in-vivo studies demonstrated a somatostatin receptor expression in some non-medullary thyroid carcinomas. In this study we investigated the somatostatin receptor status for this particular tumor entity in a larger patient group., Subject and Methods: We compared 131-iodine with 111-In-pentetreotide scans in 24 patients with metastasizing, non-medullary thyroid cancer. The findings were correlated with other imaging modalities. Additionally, we performed receptor autoradiography in one patient, octreotide therapy in another patient and administration of 90-Y- and 111-In-DOTATOC in 2 consecutive patients., Results: In the 15 patients with papillary or follicular carcinoma, 111-In-pentetreotide was inferior to 131-I in 8/15, equal in 1/15, and superior in 6/15 patients. In 8/9 of the patients with Hürthle cell carcinoma, metastases showed a 111-In-pentetreotide accumulation of various intensity, while 131-iodine scans were negative except for one patient. 111-In-pentetreotide was equal or superior compared to 201-Tl or 99m-Tc-sestamibi, but for the most part inferior in comparison with 18-F-FDG-PET. The findings of 111-In-pentetreotide scintigraphy correlated well with the receptor autoradiography and the accumulation of DOTATOC, but not with the therapeutic effect of "cold" octreotide on the thyroid cancer metastases., Conclusions: Several metastases of papillary and follicular carcinoma, and the majority of Hürthle cell cancer metastases can express somatostatin receptors. 111-In-pentetreotide scintigraphy is a promising tool for localization of metastases especially in Hürthle cell cancer or if PET is not available, and may be useful for selection of possible candidates, if therapeutic effective beta-emitting somatostatin analogues will be available for routine application.

Nuclear medicine is potentially of great value in assessing renal function. Due to the many simple methods which have been proposed and new developments in renal radiopharmaceuticals and computer software, quick, reliable and precise answers to questions from clinicians are possible. Depending on the needs and infrastructure of each clinic, and due to specific renal radiopharmaceuticals combined with the simplicity of radioactivity measurements, plasma clearance can be obtained from one or two plasma samples within 45 minutes with good accuracy. More widely used methods require the gamma camera, which gives the same functional results but, besides the global function, split renal function is obtainable. Today we have radiopharmaceuticals which are well validated. They measure functional parameters such as glomerular filtration rate (GFR) and the effective renal plasma flow (ERPF). Others can be used to give morphological information. The recently developed drugs can be labeled with Tc-99m, work-horse of the nuclear medicine physician. This radionuclide combines optimal physical properties (ideal gamma energy [140 keV]), no beta emission, short half life (6 h) and consequent low radiation dose to the patient) with low cost and permanent availability. Of the many agents cleared by GFR, two are mainly used in the clinic (chromium-51-EDTA and Tc-99m-DTPA). The first agent is very reliable due to its radiochemical and biological properties, but only the latter can be used when imaging is required. Two agents which are actively secreted by the renal tubules are available for the estimation of ERPF: radioiodinated ortho-iodohippurate (OIH) as radioactively labeled analog of the classic agent para-aminohippurate (PAH), and the new drug Tc-99m-mercaptoacetyltriglycine (MAG3).(ABSTRACT TRUNCATED AT 250 WORDS)