EJNMMI Research

Table 2 Repeatability metrics for [¹⁵O]water cerebral blood flow (CBF) and [¹³N]ammonia two tissue compartment model parameters for grey matter and selected regions of interest (ROIs)

From: Evaluation of [ ¹³ N]ammonia positron emission tomography as a potential method for quantifying glutamine synthetase activity in the human brain

	[¹⁵O]water [n = 8]			[¹³N]ammonia [n = 5]
ROI	CBF			K₁			k₂			k₃
	ICC	VAR	AbsVAR	ICC	VAR	AbsVAR	ICC	VAR	AbsVAR	ICC	VAR	AbsVAR
Grey Matter	0.50	3 ± 11	9 ± 6	− 0.79	− 7 ± 13	10 ± 11	0.94	29 ± 18	29 ± 18	0.02	− 30 ± 179	153 ± 62
White Matter	0.69	2 ± 10	7 ± 6	− 0.89	− 6 ± 13	9 ± 10	0.93	28 ± 18	28 ± 18	− 0.05	− 46 ± 163	141 ± 67
Hippocampus_l	0.17	5 ± 13	11 ± 9	0.35	− 4 ± 13	10 ± 8	0.62	34 ± 44	48 ± 23	0.22	15 ± 49	39 ± 27
OL_ling_G_l	0.22	2 ± 13	10 ± 9	− 0.42	− 8 ± 15	10 ± 14	0.86	21 ± 13	21 ± 13	− 0.00	71 ± 165	147 ± 80
G_cing_post_l	0.68	2 ± 9	8 ± 4	− 0.78	− 7 ± 13	9 ± 11	0.86	34 ± 24	34 ± 24	0.15	13 ± 196	173 ± 37
Putamen_l	0.85	2 ± 8	7 ± 2	− 0.84	− 9 ± 14	12 ± 12	0.85	31 ± 24	31 ± 24	− 0.00	59 ± 194	181 ± 33
Thalamus_l	0.66	2 ± 9	7 ± 5	− 0.64	− 7 ± 15	11 ± 11	0.76	35 ± 27	37 ± 25	0.42	80 ± 95	105 ± 57
Cerebellum_l	0.69	3 ± 12	9 ± 7	− 0.58	− 8 ± 13	9 ± 13	0.91	30 ± 27	32 ± 24	0.22	− 58 ± 157	138 ± 73

The table presents the intraclass correlation coefficient (ICC), percent mean fractional difference (VAR) and percent absolute fractional difference (AbsVAR) across test and retest scans. Data are presented as mean ± standard deviation for grey matter, white matter and the left (l) hippocampus, lingual gyrus (OL_ling_G), posterior cingulate gyrus (G_cing_post), putamen, thalamus, and cerebellum

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