TABLE 2.

Summary of ratios of CT perfusion parameters (subsampled/reference) estimated using mixed-effects modeling. Interval and point estimates for the mean ratios (subsampled/reference) are provided for each CT perfusion parameter, in tumor and normal liver. A ratio >1 indicates subsampled results were larger than reference. Boldface values represent statistically significant differences after adjusting for multiple comparisons using Bonferroni’s correction.

		Tumor			Normal Liver
Parameter	Sampling Interval	Mean Ratio	99% Confidence Interval	P-value	Mean Ratio	99% Confidence Interval	P-value
BF	1s	1.06	1.02 – 1.12	0.0009	1.03	0.99 – 1.07	0.10
	2s	1.31	1.22 – 1.40	<0.0001	1.28	1.22 – 1.34	<0.0001
	3s	1.47	1.32 – 1.64	<0.0001	1.46	1.35 – 1.58	<0.0001
	4s	1.63	1.44 – 1.84	<0.0001	1.64	1.47 – 1.82	<0.0001
BV	1s	0.99	0.96 – 1.03	0.71	0.98	0.96 – 1.01	0.10 [0.19*]
	2s	1.10	1.06 – 1.15	<0.0001	1.03	0.99 – 1.07	0.05 [0.13*]
	3s	1.20	1.13 – 1.27	<0.0001	1.09	0.97 – 1.21	0.06 [0.10*]
	4s	1.29	1.18 – 1.41	<0.0001	1.13	0.98 – 1.29	0.03 [0.05*]
MTT	1s	0.93	0.91 – 0.94	<0.0001	0.96	0.94 – 0.98	<0.0001
	2s	0.82	0.78 – 0.87	<0.0001	0.83	0.80 – 0.87	<0.0001
	3s	0.77	0.71 – 0.83	<0.0001	0.76	0.72 – 0.80	<0.0001
	4s	0.71	0.65 – 0.78	<0.0001	0.70	0.65 – 0.75	<0.0001
PS	1s	0.97	0.95 – 0.99	0.0002	0.98	0.97 – 0.99	0.0002
	2s	0.94	0.91 – 0.96	<0.0001	0.91	0.89 – 0.93	<0.0001
	3s	0.90	0.87 – 0.94	<0.0001	0.85	0.82 – 0.88	<0.0001
	4s	0.86	0.82 – 0.91	<0.0001	0.80	0.76 – 0.84	<0.0001
HAF	1s	0.99	0.96 – 1.02	0.52	1.09	1.04 – 1.13	<0.0001
	2s	0.93	0.89 – 0.97	<0.0001	1.23	1.05 – 1.43	0.0012
	3s	0.89	0.82 – 0.96	0.0003	1.34	1.05 – 1.72	0.0028
	4s	0.87	0.80 – 0.94	<0.0001	1.49	1.10 – 2.03	0.0011

^*p-values resulting from robust estimation (as described in Statistical analysis).