Real-time elastography of hepatic thermal lesions in vitro: histopathological correlation

To evaluate the reliability of elastography, a new ultrasonographic method, for delineating thermal lesion boundaries in porcine liver tissue by comparing lesion dimensions determined by real-time elastography with the findings at gross pathology.

A total of 15 thermal lesions with diameters ranging from 17 to 60 mm were created using radiofrequency ablation (RFA). Color-coded elastography was performed by one experienced examiner, using a 6 - 15 MHz high frequency linear transducer (LOGIQ E9, GE). Lesions were examined using B-mode and real-time elastography (RTE). Lesion detection, delineation and size were assessed using B-mode and RTE immediately after each thermal ablation ( < 5 min). Measurements of the sections representing the same image plane used for elastography were taken during pathologic examination and compared to the measurements obtained from the elastograms.

In our sample a statistically significant correlation in vitro between RTE and pathological measurements with respect to the lesion's principal axis and area (r2 = 0.9338 long axis, r2 = 0.8998 short axis and r2 = 0.9676 area) was found. Overall, elastography slightly underestimated the lesion size, as judged by the digitalized pathologic images.

These results support that RTE outperforms conventional B-mode ultrasound and could potentially be used for the routine assessment of thermal therapies.