A comparison of HIFU-induced lesion size measurement based on gross histological examination and image of bovine thigh in vitro

The aim of this study was to investigate the agreement in HIFU-induced lesion sizes between measurements based on gross histological examination and those from images. Experiments were conducted in an experimental arrangement with a three-way multiscan ultrasonic inspection system and imaging was done by B-mode ultrasound (US). Bovine thigh muscle with and without fascia lata was treated with an in situ spatially averaged focal intensity ranging between 750 W cm^-2 and 1565 W cm^-2 and sonication-time was variable from 8 to 20 s. Assessment of the two measurement methods showed a rather weak correlation in the samples without fascia lata. For clarity and convenience in the discussion, sample muscles with and without fascia lata were labeled F and M, respectively. It was difficult to measure the lesion size from ultrasonographic images of F samples, so there was disagreement in the samples with fascia lata. This investigation showed that the presence of fascia lata in bovine thigh muscle has the likely effect of affecting the ultrasound image and makes it difficult to distinguish coagulated tissue from surrounding healthy tissue. There was no significant correlation between ultrasonography and the gross histological findings in M samples. Data supported that at for an in situ spatially averaged focal intensity ranging between 750 W cm^-2 and 1565 W cm^-2 and relatively shorter exposures (sonication-time variable from 1 to 8 s) higher correlation between image and gross histology measurement was found in excised bovine muscle specimens.