Objective: Our goal was to define the lesion enhancement characteristics of renal cell carcinoma metastases to the pancreas using three-phase helical CT.
Materials and methods: Thin-section three-phase contrast-enhanced CT scans of nine patients with renal cell carcinoma metastases to the pancreas were evaluated. The helical CT protocol included 3-mm collimation and a 2:1 pitch. Scans through the pancreas were obtained in three series beginning 25, 60, and 120 sec after the start of administration of i.v. contrast material delivered at 3 ml/sec. The Hounsfield densities of the pancreatic lesions and normal pancreatic parenchyma during each of the enhancement phases were recorded and compared.
Results: The enhancement patterns of the metastatic deposits and the normal pancreas differed. Thirty-four lesions ranging in size from 6 to 110 mm were identified. All metastases showed rapid enhancement during the early (arterial and portal) phases, resulting in differential attenuations (compared with normal pancreatic parenchyma) of approximately 50-100 H. The differential attenuations were approximately 5-45 H on delayed-phase scans, resulting in poorer conspicuity of the lesions. Multifocal metastases were clearly identified on the early-phase scans in seven patients.
Conclusion: Renal cell carcinoma metastases to the pancreas enhance most conspicuously during the early phases of helical CT. Such metastases may fail to be appreciated in the delayed phase. In patients with suspected renal cell carcinoma metastases to the pancreas, early-phase scanning after i.v. contrast administration should be performed.