[Localization of islet cell tumors using sonography, computed tomography, arteriography and selective transhepatic venous sampling for hormone assay (author's transl)].

Of 29 patients examined operation revealed a malignant tumor in 9 and a benign insulinoma in 18, 2 insulinomas were not found. The problems of preoperative tumor localization were limited to small insulinomas (size 7-35 mm). Ultrasound detected all of 3 insulinomas as low echogenic structures (size 7, 8, 17 mm). Computed tomography demonstrated 4 of 5 insulinomas (size 7, 8, 15, 17 mm) due to contrast enhancement following bolus injection. Arteriography localized 12 of 18 insulinomas preoperatively and 14 of 18 retrospectively. Selective transhepatic venous sampling for insulin assay identified 7 of 8 tumors. Real-time ultrasound and dynamic CT are promising in the diagnostics of insulinomas over 7 mm and should precede arteriography. Selective transhepatic venous sampling as the last diagnostic step is a major procedure and most specific, but not always without problems in interpretation.