Are CAT-scans necessary for preoperative localization of insulinomas?

Do CAT-scans provide useful information in terms of preoperative localization of insulinomas after a biochemical diagnosis is established or may CAT-scan imaging be safely abandoned?

CAT-scan results from 30 consecutive patients between 1980-1990 with established insulinomas were retrospectively evaluated with regard to actual tumour size (volume) and identification and localization as verified during surgery.

In all patients, the tumours were easily detected by manual palpation during surgery, although the size of 67% of the tumours (n = 20) was less than 2.5 cm3. In only 7 patients (23%) the tumour had been correctly localized by computer tomography. Detected tumours were significantly larger than undetected tumours (median size 5.3 vs 1.3 cm3; p < 0.005).

Despite the low sensitivity of computer tomography as documented in this study, all patients with an insulinoma were definitely cured after surgical intervention. Thus, CAT-scans are neither necessary nor helpful for preoperative localization of insulinomas.