Feasibility of using Nakagami distribution in evaluating the formation of ultrasound-induced thermal lesions

Abstract

The acoustic posterior shadowing effects of bubbles influence the accuracy for defining the location and range of ablated thermal lesions during focused ultrasound surgery when using ultrasonic monitoring imaging. This paper explored the feasibility of using Nakagami distribution to evaluate the ablated region induced by focused ultrasound exposures at different acoustic power levels in transparent tissue-mimicking phantoms. The mean value of the Nakagami parameter m was about 0.5 in the cavitation region and increased to around 1 in the ablated region. Nakagami images were not subject to significant shadowing effects of bubbles. Ultrasound-induced thermal lesions observed in the photos and Nakagami images were overshadowed by bubbles in the B-mode images. The lesion size predicted in the Nakagami images was smaller than that predicted in the photos due to the sub resolvable effect of Nakagami imaging at the interface. This preliminary study on tissue-mimicking phantom suggested that the Nakagami parameter m may have the potential use in evaluating the formation of ultrasound-induced thermal lesion when the shadowing effect of bubbles is strong while the thermal lesion was small. Further studies in vivo and in vitro will be needed to evaluate the potential application.

Nakagami imaging for detecting thermal lesions induced by high-intensity focused ultrasound in tissue

“…Similar to published data in Meng-Lin et al 19 and Zhang et al, 26 our study showed that the Nakagami parameter can detect HIFU thermal lesions. In contrast to previously published results, in this study, the Nakagami parameter estimated post-exposure was not merely subtracted from the pre-value to detect a HIFU thermal lesion.…”

“…Moreover, in Zhang et al, 26 tissue-mimicking phantoms were used to validate their study, whereas in the current study, the changes in the Nakagami distribution parameters were investigated after HIFU exposure to in ex vivo tissue samples. Here, the experiments were done on ex vivo tissue samples, whereas in future, it should be studied on in vivo samples.…”

Surface vibration and nearby cavitation of an ex vivo bovine femur exposed to high intensity focused ultrasound

“…[1][2][3][4][5] The clinical use of HIFU for the thermal ablation of tumors located in various tissues, including uterine fibroids, 6 brain, 7 liver, 8 kidney, 9 prostate, 10 and breast, 11 is now being investigated due to the progress in the medical imaging techniques used for targeting and monitoring HIFU during recent years, such as magnetic resonance imaging (MRI) 12,13 and ultrasound (US) imaging. 14,15 In addition to soft tissue tumors, the mass of tissue that is treated is on or near bone in many cases. [16][17][18] Bone is among the most common target organs to which cancer metastasizes, and HIFU has been clinically used for thermal ablation treatment of primary bone tumors from a variety of sites.…”

Changes in Backscattered Ultrasonic Envelope Statistics as a Function of Thrombus Age: An in Vitro Study

“…Consequently, the Nakagami distribution is a general model for ultrasound backscattering. The use of ultrasound Nakagami imaging to visualize the backscattered statistics for tissue characterization has been validated by several research groups (Gu et al 2013;Ho et al 2012Ho et al , 2013Larrue and Noble 2011;Lin et al 2011;Yang et al 2013;Zhang et al 2012). The details of the algorithm for ultrasound Nakagami imaging can be found in previous studies (Tsui and Change 2007;Tsui et al 2009, 2012b, Tsui 2012.…”