Table 4 Non-uniformity of SNR improvement in 2D lipid composition spectra using DQF-COSY.

	Algorithms	Tumour specimens (N = 17)				Healthy volunteers (N = 15, 30 voxels)				Patients Peritumoural adipose tissue (N = 15)				Patients Tumours in vivo (N = 10)
		Slopes (%/ppm)		CV (%)	P-value	Slopes (%/ppm)		CV (%)	P-value	Slopes (%/ppm)		CV (%)	P-value	Slopes (%/ppm)		CV (%)	P-value
		Diag	Off diag	CV (%)	P-value	Diag	Off diag	CV (%)	P-value	Diag	Off diag	CV (%)	P-value	Diag	Off diag	CV (%)	P-value
External reference	WSVD	0.53	2.72	23.2 (19.7–30.8)	0.044	− 0.07	− 0.43	5.8 (4.6–6.7)	0.491	− 1.26	− 0.47	7.8 (6.4–9.8)	0.139	− 0.99	1.54	26.1 (17.7–37.2)	0.139
	nd-comb	0.60	2.59	25.2 21.3–29.8)	0.022	− 0.10	− 0.42	6.0 (4.4–7.4)	0.959	− 1.34	− 0.47	8.3 (6.9–9.9)	0.445	− 1.07	1.17	25.5 (17.9–36.1)	0.445
	AOC	− 0.29	2.46	26.2 (20.9–8.3)	0.001	− 0.06	− 0.45	5.7 (4.7–6.8)	0.558	− 1.27	− 0.48	7.8 (6.4–9.7)	0.575	− 1.03	0.92	25.0 (17.3–36.3)	0.575
Internal reference	WSVD	− 3.79	4.90	21.1 13.7–28.1)	–	0.21	− 0.18	5.5 (4.2–7.2)	–	− 1.08	− 0.30	6.1 (5.0–9.0)	–	− 1.1	2.68	20.7 (17.4–31.7)	–
	nd-comb	− 1.01	1.66	33.3 (20.5–39.6)	0.006	− 0.03	− 0.28	6.6 (4.6–12.6)	< 0.001	− 0.99	− 0.88	7.9 (6.4–1.4)	0.374	− 1.2	2.3	26.4 (23.0–30.9)	0.374
	AOC	− 0.65	2.02	23.3 (15.8–33.3)	0.002	− 0.11	− 0.24	5.0 (4.4–8.4)	0.567	− 0.90	− 0.48	8.2 (5.6–0.7)	0.575	− 3.4	0.41	22.7 (18.1–28.2)	0.575

Data for CV are medians (interquartile range). Slope along the diagonal is positive from (0.9, 0.9) ppm to (5.3, 5.3) ppm. Slope along the off diagonal is positive from reading t₂/F₂ at (0.9, 5.3) ppm to mixing t₁/F₁ at (5.3, 0.9) ppm. P-value represents the comparison on CV values between the noise decorrelated algorithms using Wilcoxon signed-rank tests. Results are presented with WSVD_i as a reference for comparison. Data with negative SNR improvement were excluded (1 dataset from a healthy volunteer using AOC_i, 1 dataset from a healthy volunteer using nd-comb_i, and 1 dataset from a tumour in patients using nd-comb_i). AOC = adaptively optimised combination, CV = coefficient of variance, nd-comb = noise decorrelated combination, WSVD = whitened singular value decomposition.

Search