Table 1.

Summary of selected high intensity focused ultrasound (HIFU) studies and imaging findings across multiple modalities. We summarize a selection of imaging findings following both thermal and mechanical HIFU ablation. Two radiofrequency ablation (RFA) studies are also included due to novelty of the imaging methods and its applicability to thermal HIFU assessment.

	Study	Ablation modality	Imaging modality	Clinical/preclinical	Animal model	Findings
MRI	Hoogenboom et al. [5]	HIFU (boiling histotripsy)	Noncontrast T2 MRI	Preclinical	C57B/6 mice EL4 thymoma	Ablated region is hyperintense with hypointense rim on noncontrast T2w MRI
	Rouviere et al. [7]	HIFU (thermal)	Contrast-enhanced T1 MRI	Clinical	N/A	Ablated region is nonenhancing accompanied (variably) with a hyperintense rim due to hyperemia
	Pilatou et al. [8]	HIFU (thermal)	Diffusion-weighted and ADC MRI	Clinical	N/A	Ablated lesions have increased intensity on high $b$ value DWI images
	Liao et al. [9]	HIFU (thermal)	Diffusion-weighted MRI	Clinical	N/A	Reduction in ADC following ablation; high-signal ring around ablated region on DWI
	Vidal-Jove et al. [10]	HIFU (histotripsy)	Contrast-enhanced T1 MRI	Clinical	N/A	Mechanically disrupted region appears as a nonperfused volume
	Morochnik et al. [11]	HIFU (thermal)	T2 map MRI	Clinical	N/A	T2 increases during HIFU treatment
	Worlikar et al. [12]	HIFU (histotripsy)	T2w MRI	Preclinical	Sprague-Dawley rats N1-S1 hepatic tumors	Ablated region hypointense immediately following ablation followed by gradual resorption
	Lee et al. [13]	HIFU (thermal)	13C MRI	Preclinical	C57Bl6 X FVB TRAMP prostate cancer model	Ablated regions exhibited 13C lactate and 13C urea intensity similar to background. Partially ablated regions had decreased intensity which recovered after 5 days
CT	Yang et al. [14]	HIFU (thermal)	Contrast-enhanced CT	Preclinical	Rabbit Healthy liver	Ablated lesion is low-density and nonenhancing
	Orgera et al. [15]	HIFU (thermal)	Contrast-enhanced CT	Clinical	N/A	Nonenhancing ablated lesion appears shortly after ablation
US	Luo et al. [16]	HIFU +/- microbubbles	US	Preclinical	Rabbit VX2 liver tumor	Transient hyperechogenicity after ablation on b-mode
	Sasaki et al. [17]	HIFU (thermal)	US	Preclinical	Ex vivo porcine liver	Decorrelation between RF frames during HIFU
	Zhou et al. [18]	HIFU (thermal)	Doppler US	Clinical	N/A	No blood flow on Doppler after HIFU ablation
	Vlaisavljevich et al. [19]	HIFU (histotripsy)	US	Preclinical	Porcine Healthy liver	Bubble cloud can be used to monitor treatment in real time
	Wright et al. [20]	HIFU (histotripsy)	US	Preclinical	Rabbit femoral artery	HIFU thrombolysis restored blood flow
PET	Chen et al. [21]	RFA	18FDG PET	Clinical	N/A	PET had increased sensitivity (94.1%) and specificity (81.3%) to recurrent tumor after thermal ablation
	Orgera et al. [15]	HIFU (thermal)	18FDG PET	Clinical	N/A	Reduction in metabolic activity after HIFU delineates ablation margins
	Shyn et al. [22]	RFA	13N ammonia and 18FDG PET	Clinical	N/A	Entire ablation margin can be assessed intraprocedurally