Real‐time sonoelastography of hepatic thermal lesions in a swine model

Abstract

Sonoelastography has been developed as an ultrasound-based elasticity imaging technique. In this technique, external vibration is induced into the target tissue. In general, tissue stiffness is inversely proportional to the amplitude of tissue vibration. Imaging tissue vibration will provide the elasticity distribution in the target region. This study investigated the feasibility of using real-time sonoelastography to detect and estimate the volume of thermal lesions in porcine livers in vivo. A total of 32 thermal lesions with volumes ranging from 0.2 to 5.3 cm 3 were created using radiofrequency ablation ͑RFA͒ or high-intensity focused ultrasound ͑HIFU͒ technique. Lesions were imaged using sonoelastography and coregistered B-mode ultrasound. Volumes were reconstructed from a sequence of two-dimensional scans. The comparison of sonoelastographic measurements and pathology findings showed good correlation with respect to the area of the lesions ͑r 2 = 0.8823 for RFA lesions, r 2 = 0.9543 for HIFU lesions͒. In addition, good correspondence was found between threedimensional sonoelastography and gross pathology ͑3.6% underestimate͒, demonstrating the feasibility of sonoelastography for volume estimation of thermal lesions. These results support that sonoelastography outperforms conventional B-mode ultrasound and could potentially be used for assessment of thermal therapies.

Medical ultrasound: imaging of soft tissue strain and elasticity

“…In some patients, good correlation was found between MRI and ultrasonic strain imaging of the lesion. The method using externally applied vibration in pig livers also showed good correspondence between three-dimensional elastography and pathological findings for HIFU lesions [220].…”

Multi-parametric monitoring of high intensity focused ultrasound (HIFU) treatment using harmonic motion imaging for focused ultrasound (HMIFU)

“…Previous imaging approaches have been established and implemented for HIFU lesion monitoring and treatment assessment in both MRI and ultrasound [2][3][4][5][6][7][8][9]. Since it is known that the Young's Modulus of HIFU-induced thermal lesion were 2 to 12 times higher than the untreated tissue [10][11], imaging the HIFU lesions based on their distinct mechanical properties has been investigated by numerous elasticity imaging techniques. Harmonic Motion Imaging (HMI) utilizes a simple configuration consisting of a single transducer for both interrogating and/or ablating tissue [12,13] with real-time displacement tracking during application of the acoustic radiation force by an Amplitude modulated (AM)-HIFU beam.…”

Extracorporeal ultrasound-guided high intensity focused ultrasound therapy: Present limitations

“…In porcine livers, the lesion boundary was clear in elastograms, but not visualized in grayscale images in 42.9% cases. The sizes of a HIFU lesion calibrated with elastograms accorded with the actual values (R 2 were 0.9543, 0.8555 and 0.9079 for area, long axis and short axis) (Zhang et al, 2008). Elastograms can be combined with grayscale ultrasound images to monitor HIFU ablation in real time.…”