Diagnostic Value of CT of Chest, Abdomen, and Pelvis in Patients With Solitary and Multiple Brain Lesions.

A common goal in patients with newly discovered brain lesions is to determine if the lesions are primary malignant brain neoplasms, metastases, or benign entities. Such patients often undergo CT of the chest, abdomen, and pelvis (CT CAP) to identify a primary neoplasm that may have metastasized to the brain. The aim of this study is to determine the frequency of finding a primary cancer on CT CAP. A large academic hospital imaging database was searched for cases of new intracranial lesions with subsequent CT CAP performed for metastatic workup. The frequency of primary neoplasms diagnosed in the chest versus abdominal and pelvic portions of CT scans was determined in patients with newly identified intraaxial and extraaxial brain lesions. Lesion characteristics were recorded including size, number, and the presence of enhancement and hemorrhage. Ancillary signs of an abdominopelvic neoplasm were also recorded. A total of 227 of 287 (79%) cases of newly discovered intracranial lesions were malignant (primary or metastatic) and 60 (21%) were benign. Of the 227 malignant cases, 136 (60%) were primary brain neoplasms and 91 (40%) were brain metastases, and 68 of the 91 (75%) lung primary. Chest CT (CTC) identified a primary neoplasm in 65 of 287 (23%) cases; 63 of those 65 (96%) neoplasms arose in the lungs. CT of the abdomen and pelvis (CTAP) identified a primary neoplasm in only 3 of 287 (1%) cases. In 26 cases in which the intracranial lesions did not enhance, only one was metastatic. In patients with newly discovered brain lesions, CTC is warranted, but CTAP is unlikely to be useful in patients without ancillary signs of abdominopelvic neoplasm.