Ultrafast Cone-Beam Computed Tomography: A Comparative Study of Imaging Protocols during Image-Guided Therapy Procedure

Table 6

Quantitative image quality parameters and tumor delineation obtained from ultrafast CBCT image data with contrast material injection for both examined protocols. Furthermore, TLC represents tumor-to-liver contrast.

Image quality parameter	Measurement locations
	Normal hepatic parenchyma	Hypoenhanced tumor (A)	Heterogeneously enhanced tumor (B)	Homogenously enhanced tumor (C)
Protocol 1
Hounsfield unit (HU)	54 ± 13 (41–68)	25 ± 8 (14–37)	63 ± 15 (47–77)	151 ± 17 (119–196)
Image noise (HU)	42 ± 11 (37–49)	52 ± 18 (39–59)	62 ± 17 (51–73)	83 ± 22 (69–99)
Signal-to-noise ratio (SNR)	1.3 (1.15–1.4)	0.48 (0.35–0.58)	1 (0.98–1.1)	1.8 (1.7–1.93)
Tumor-to-liver contrast (TLC)	—	−29 (−18–−39)	9 (4–14)	97 (91–113)
Protocol 2
Hounsfield unit (HU)	83 ± 14 (69–95)	10 ± 3 (6–15)	115 ± 20 (74–147)	217 ± 21 (169–244)
Image noise (HU)	29 ± 9 (25–35)	17 ± 7 (13–23)	44 ± 15 (32–52)	60 ± 19 (49–66)
Signal-to-noise ratio (SNR)	2.85 (2.75–3)	0.7 (0.4–0.8)	2.6 (2.3–2.8)	3.6 (3.5–3.7)
Tumor-to-liver contrast (TLC)	—	−73 (−59–−89)	32 (21–41)	134 (119–162)
value (protocol 1 versus protocol 2):	0.0001	0.0001	0.0001	0.0001