Needle tract implantation after sonographically guided percutaneous biopsy of hepatocellular carcinoma: Evaluation of doubling time, frequency, and features on CT

OBJECTIVE. The purpose of this study was to evaluate the doubling time, frequency, and features on dynamic CT of extrahepatic needle tract implantation of malignant neoplasms after sonographically guided percutaneous biopsy for hepatocellular carcinoma (HCC). MATERIALS AND METHODS. Between January 1997 and June 2003,1,055 patients underwent sonographically guided percutaneous biopsy for HCC. The serial changes of implanted tumor volume were estimated on retrospective review of CT, and their doubling times were calculated from the two CT scans showing the first and last visible implanted tumors. The frequency of extrahepatic needle tract implantation of malignant neoplasms was evaluated overall and according to the type of needle used. The CT features of the implanted tumors were examined with regard to size, number, location, morphology, and enhancement pattern. RESULTS. The mean doubling time of extrahepatic needle tract implantation of malignant neoplasms after sonographically guided percutaneous biopsy was 112 days (range, 22-415 days). The mean time interval between biopsy and the emergence of the implanted tumor on CT was 267 days (range, 116-619 days). The overall frequency was 0.76% (8/1,055). The frequencies according to the type of needle were 1.3% (8/622) for the group treated with the end-cutting needle and 0% (0/433) for the group treated with the tru-cut needle; these frequencies differ from each other with statistical significance (p < 0.05, Fisher's exact test). Fifteen of the 17 implanted tumors were round or oval enhancing nodules along the needle tract, and 13 showed persistent enhancement on equilibrium phase images. CONCLUSION. The doubling times of extrahepatic needle tract implantation of malignant neoplasms after sonographically guided percutaneous biopsy for HCC were similar to those of typical HCCs in the liver on CT-based analysis. The frequency was relatively low, and their CT features were similar to those reported previously.