Histological characterization of HIFU lesions

Area of Science:

• Medical imaging and diagnostics
• Ultrasound technology
• Histopathology

Background:

• High intensity focused ultrasound (HIFU) offers thermal ablation for tissue destruction.
• Biological and histological effects of HIFU, including acoustic cavitation and tissue boiling, require further documentation.
• In vivo rat liver models provide a platform for detailed HIFU exposure analysis.

Purpose of the Study:

• To document the biological and histological effects of HIFU in rat livers.
• To characterize damage regions resulting from HIFU with and without acoustic cavitation/tissue boiling.
• To elucidate similarities and differences in HIFU-induced thermal lesions.

Main Methods:

• Utilized well-characterized HIFU exposures in rat livers.
• Distinguished between exposures causing thermal damage with and without acoustic cavitation/tissue boiling.
• Employed hematoxylin and eosin (H&E), picrosirius red, and immunohistochemical staining for histological assessment.
• Detected cavitation activity using active and passive methods.

Main Results:

• Identified distinct concentric damage regions with hemorrhage, increased extracellular spaces, and heat-fixed cells.
• Observed unique centermost zones with irregular holes when acoustic cavitation/boiling occurred.
• Detected cleaved caspase-3 and Hsp70 staining in the hemorrhage periphery, indicating an inflammatory response.
• Noted the formation of an acellular region in the lesion center by day 7.

Conclusions:

• HIFU induces characteristic concentric damage zones in liver tissue.
• Acoustic cavitation and tissue boiling significantly alter the central lesion morphology.
• Histological analysis reveals inflammatory responses and cellular changes following HIFU ablation.