Performing MR-guided biopsies in clinical routine: factors that influence accuracy and procedure time

To assess the accuracy, the duration and factors that influence the duration of MRI-guided liver or soft-tissue biopsies. Nineteen liver biopsies and 19 soft-tissue biopsies performed using 1.5T-MRI guidance were retrospectively analysed. Diagnostic performance and complications were assessed. Intervention time was subdivided into preparation period, puncture period and control period. Correlation between procedure time and target size, skin-to-target-distance, used sequences and interventionalists' experience were analysed. Overall sensitivity, specificity and accuracy were 0.86, 1.0 and 0.92, respectively. Two minor complications occurred. Overall median procedure time was 103.5 min. Liver biopsies lasted longer than soft-tissue biopsies (mean[soft-tissue]: 73.0 min, mean[liver]: 134.1 min, P < 0.001). The most time consuming part was the preparation period in both, soft-tissue and liver biopsies corresponding to 59.6% and 47.4% of the total intervention time, respectively. Total procedure time in liver biopsies (P = 0.027) and puncture period in liver and soft-tissue biopsies (P[liver] = 0.048, P[soft-tissue] = 0.005) was significantly prolonged for longer skin-to-target-distances. Lower numbers of image acquisitions (P[liver] = 0.0007, P[soft-tissue] = 0.0012) and interventionalists' experience reduces the procedure duration significantly (P < 0.05), besides all false-negative results appeared during the first five biopsies of each individual radiologist. The interventionalists' experience, skin-to-target-distances and number of image acquisition influence the procedure time significantly. (orig.)