Table 3.

Overview of diaphragm motion during the breathing control strategies under investigation

Median (range) values	MRI1	MRI2	N	p-value
Testing differences between MRI sessions
DIBH IQR (mm)	5.4 (1.2–14.9)	4.0 (1.0–23.6)	14	0.221
FB amplitude (mm)	20.2 (10.6–31.9)	22.1 (12.8–41.9)	14	0.362
RB amplitude (mm)	11.3 (6.2–20.3)	16.6 (9.3–23.8)	14	0.024
PIBH drift (mm/minute)	3.0 (0.4–6.5)	2.7 ( 0.9–6.0)	15	0.125
PEBH drift (mm/minute)	4.9 (2.2–7.9)	3.8 (1.8–15.1)	14	0.064

Median (range) values	FB	RB	N	p-value
Testing differences between breathing control strategies
MRI1 amplitude (mm)	20.2 (10.6–31.9)	11.3 (6.2–20.3)	14	< 0.001
MRI2 amplitude (mm)	22.1 (12.8–41.9)	16.6 (9.3–23.8)	14	0.002
MRI1 & MRI2 amplitude (mm)	20.9 (10.6–41.9)	12.8 (6.2–23.8)	28	< 0.001

Median (range) values	PIBH	PEBH	N	p-value
Testing differences between breathing control strategies
MRI1 drift (mm/minute)	3.0 (0.4–6.5)	4.9 (2.2–7.9)	14	0.002
MRI2 drift (mm/minute)	2.7 ( 0.9–6.0)	3.8 (1.8–15.1)	15	0.001
MRI1 & MRI2 drift (mm/minute)	3.0 (0.4–6.5)	4.4 (1.8–15.1)	29	< 0.001

Bold values indicate the significant p-values

For deep inspiration breath-holds (DIBHs), diaphragm motion is expressed by the inter-quartile range (IQR) of the consecutive breath-holds. For free breathing (FB) and regularized breathing (RB) at 22 breaths per minute the diaphragm motion is quantified by the breathing motion amplitude measured on 4DMRIs. For prolonged breath-hold from inhalation (PIBH) and exhalation (PEBH), diaphragm motion is expressed in the diaphragm drift velocity. Due to missing data and unsuccessful reconstructions, the number of pairs to be compared (N) per test varies. Significance was tested with a Wilcoxon signed-rank test (α = 0.05). P-value is shown in boldface when the difference was significant