Abstract
Trans-arterial chemoembolization (TACE) is an important yet variably effective treatment for management of hepatic malignancies. Lack of response can be in part due to inability to assess treatment adequacy in real-time. Gold-standard contrast enhanced computed tomography and magnetic resonance imaging, although effective, suffer from treatment-induced artifacts that prevent early treatment evaluation. Non-contrast ultrasound is a potential solution but has historically been ineffective at detecting treatment response. Here, we propose non-contrast ultrasound with recent perfusion-focused advancements as a tool for immediate evaluation of TACE. We demonstrate initial feasibility in an 11-subject pilot study. Treatment-induced changes in tumor perfusion are detected best when combining adaptive demodulation (AD) and singular value decomposition (SVD) techniques. Using a 0.5 s (300-sample) ensemble size, AD + SVD resulted in a 7.42 dB median decrease in tumor power after TACE compared to only a 0.06 dB median decrease with conventional methods.
Highlights
Liver cancer remains the 5th and 9th leading cause of cancer-related deaths globally among men and women, respectively[1]
Compared to Contrast-enhanced ultrasound (CE-US), conventional non-contrast Doppler ultrasound imaging measures the signal from moving red blood cells directly as opposed to contrast agents, making it is less susceptible to misleading enhancements from the Trans-arterial chemoembolization (TACE) treatment
Doppler ultrasound techniques without contrast have been shown to be limited by attenuation and tissue clutter for perfusion imaging applications in the past[12,13,14], there have been several significant advancements to slow blood flow imaging with ultrasound in recent years that have yet to be assessed for use in TACE treatment evaluation
Summary
Liver cancer remains the 5th and 9th leading cause of cancer-related deaths globally among men and women, respectively[1]. Because TACE intends to substantially reduce tumor blood perfusion, complete response is indicated by absence of enhancement in the tumor, and residual tumor manifests as hyper-enhancement in follow-up images Both are effective evaluation tools, but follow-up imaging is not performed until at least 4–6 weeks after treatment to allow time for treatment-related imaging artifacts to subside[5,8]. Compared to CE-US, conventional non-contrast Doppler ultrasound imaging measures the signal from moving red blood cells directly as opposed to contrast agents, making it is less susceptible to misleading enhancements from the TACE treatment. For this reason, non-contrast ultrasound is a potential solution for treatment assessment during or immediately after treatment. The introduction of power Doppler helped to overcome this problem because it computes the energy of the Doppler signal or the amount of moving blood as opposed to velocity, making it more sensitive to weak perfusion signal in addition to being relatively angle independent[15,18]
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