Detection of small pancreatic tumors with multiphasic helical CT

OBJECTIVE. The purpose of this study was to evaluate the sensitivity and specificity of helical CT in the detection of adenocarcinomas of the pancreas measuring 2 cm or smaller at pathologic examination. MATERIALS AND METHODS. Thin-section triple phase (20, 40, and 70 sec after the start of injection) contrast-enhanced helical CT scans of the abdomen in 18 patients with a pancreatic carcinoma that was 2 cm or smaller and 18 patients with a normal pancreas were retrospectively reviewed by two senior radiologists who specialized in oncologic abdominal imaging. Discrepancies were resolved by consensus. The observers were unaware of the clinical information. CT scans were evaluated for the presence of a pancreatic mass, bile, and pancreatic duct stricture. The location and size of tumors as determined on CT were compared with pathologic findings. The CT results were also compared with the prospective CT interpretations derived from the radiology reports and with the endoscopic sonographic reports when available. RESULTS. The sensitivity of thin-section triple-phase helical CT in the detection of small pancreatic masses was 77%, and the specificity was 100% for the two experienced observers. The sensitivity and specificity were 72% and 100%, respectively, for the prospective interpretations done by 10 observers. There was no correlation between the tumor size at pathology and the CT measurements. CONCLUSION. Thin-section contrast-enhanced helical CT is sensitive and highly specific for the detection of pancreatic tumors measuring 2 cm or smaller. Improvement in the detection rate of this technique compared with previous techniques lies in the optimization of parenchymal enhancement during the pancreatic phase and the decrease in slice thickness.