CT-based thermometry: An overview

Figures & data

Figure 1. Schematic representation of the phenomena explaining the CT value dependence on tissue temperature.

Figure 2. (A) Water calibration phantom, (B) CT-slice of the water phantom, (C) histograms of the CT values of water equivalent phantoms at two different temperatures (T2 > T1).

Figure 3. CT number dependence on temperature of water. (A) Trend of CT value with temperature of distilled water phantom and parabolic curve fitting, adapted from [29], (B) trend of CT value with temperature of water, adapted from [18], (C) trend of CT value with temperature of water and linear fitting, adapted from [22], (D) trend of CT value with temperature of different materials and linear fittings, adapted from [26].

Table 1. Comparison between experimental parameters and results of different studies on water-equivalent phantoms.

Main researcher	Phantom material	kVp	mAs	Slice thickness [mm]	ROI [mm^2]	Thermal sensitivity [HU/°C]
Fallone [16]	Water	120	–	15	276	−0.40
Bentzen [29]	Water	120	–	10	–	−0.32 ± 0.03
Jenne [18]	Water	–	–	8	20	−0.35 ± 0.01
Bruners [22]	Water	140	250	9.6	10	−0.447 ± 0.004
Homolka [26]	Water	120	1200	10	314	−0.29 ± 0.001
	Plastic water					−0.55 ± 0.001
	Solid water					−0.25 ± 0.001
	X0					−0.72 ± 0.003
	PSPP-1					−0.27 ± 0.001
	EPX-W					−0.23 ± 0.001

Figure 4. Trend of CT number as a function of temperature of different ex-vivo tissues. (A) Ex vivo bovine liver undergoing radiofrequency ablation, adapted from [37], (B) ex vivo bovine liver undergoing LITT, adapted from [31], (C) ex vivo porcine pancreas undergoing LITT, adapted from [20].

Table 2. Comparison between experimental parameters and results of different studies on ex vivo and in-vivo tissues.

Reference	Heating technique	kVp	mAs	Slice thickness [mm]	ROI [mm^2]	Experiment type	Thermal sensitivity [HU/°C]
Pandeya et al. [30]	RFA	120	200	1.2	100	ex-vivo	−0.60 ± 0.026
Pandeya et al. [31]	LITT	120	200	1.2	100	ex-vivo	−0.65 ± 0.05
Pandeya et al. [19]	Hot air	120	200	1.2	21	ex-vivo	−0.54 ± 0.03
Bruners et al. [32]	RFA	120	320	2.4	50	in-vivo	≈−0.43
Schena et al. [20,36]	LITT	120	150	0.6	2	ex-vivo	≈−0.50

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