Image quality and diagnostic performance of free-breathing diffusion-weighted imaging for hepatocellular carcinoma

Table 1 Details of magnetic resonance parameters

Imaging technique	FB-DWI	RT-DWI
	Spin echo single-shot EPI	Spin echo single-shot EPI
SENSE factor	2	2
TR/TE (ms)	6250/56	1877/55
Flip angle (degree)	90°	90°
Field of view (mm2)	380 × 299	380 × 299
Matrix (frequency × phase)	112 × 176	112 × 68
Slice thickness (mm)	7	7
Slice gap (mm)	1	1
No. of slice	25	25
No. of excitations	2	2
b-value (s/mm2)	0.500 and 1.000	0.500 and 1.000
Respiratory compensation	Free-breathing without navigator echo	Respiratory-triggered with navigator echo
Fat-suppression	SPAIR	SPIR
SPAIR delay (ms)	100
SPAIR TR (ms)	250
Frequency offset (Hz)	250	180
EPI factor	75	25
Band width (Hz/pixel)	4050.4	4438.5
Scan time (min:s)	3:32	3:201

¹The mean scan time of RT-DWI, because these values vary depending on the subjects’ respiration condition. FB-DWI: Diffusion-weighted imaging with modified MR parameter settings for image improvement by referring to the literature[18]; RT-DWI: Respiratory-triggered diffusion-weighted imaging without modified MR parameter settings for the image improvement; EPI: Echo planar imaging; TR: Repetition time; TE: Echo time; SPAIR: Spectral attenuation with inversion recovery; SPIR: Spectral presaturation with inversion recovery; SPAIR delay: Inversion time from exposure of SPAIR pulse; SPAIR TR: TR between SPAIR pulses during the scan; Frequency offset: Bandwidth from the frequency of fat tissue; EPI factor: The number of k-space profiles collected per excitation.