Efficacy of the Focused Ultrasound as an Additional Study to Characterize Small Hepatic Lesions on CT in Patients with Cancer

ABSTRACT

PURPOSE: The purpose of this study was to evaluate the efficacy of focused ultrasound (US) to characterize small indeterminate hepatic lesions on contrast-enhanced CT in cancer patients. MATERIALS AND METHODS: Forty-three consecutive patients with proven cancers developed 70 indeterminate hepatic lesions that were less than 1.5 cm in size, as detected on contrast-enhanced CT. Two radiologists performed ultrasound focusing on the targeted area after referencing the location of the hepatic lesions on a previous CT image. When the hepatic lesions were visualized by focused US, the lesions were characterized as cysts, hemangiomas, or solid/metastases. Verification of the hepatic lesions was assessed by a histopathological examination or by follow-up imaging. RESULTS: Focused US detected 51 (73%) of 70 indeterminate hepatic nodules on CT and all of the nodules visualized on focused US could be characterized as cysts (n = 40), hemangiomas (n = 7), or solid/metastases (n = 4). All of the cysts and six hemangiomas were verified as benign lesions. One hemangioma was subsequently identified as a metastasis. Nineteen (27%) indeterminate hepatic nodules were not visible on focused US and 18 nodules were verified as benign lesions. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of focused US for differentiating metastases among indeterminate hepatic nodules less than 1.5 cm in size on CT were 66.7%, 100%, 97.1%, 100%, and 97%, respectively. CONCLUSION: Focused US may be the next appropriate examination to perform for cancer patients with indeterminate hepatic nodules detected on CT, Focused US may be a pivotal modality for defining prognosis and treatment.