Abdominal volume computed tomography assessment of body composition in dogs

Turner, R. B. S.; Hepworth, G.; Wilson, K.; Tyrrell, D.; Dunshea, F. R.; Mansfield, C. S.

doi:10.1186/s12917-018-1768-6

BMC Veterinary Research

Table 1 Linear regression statistics of CT threshold values used to estimate DXA body composition in dogs and corresponding validation of the values predicted by CT abdominal using Lin’s concordance (r_c²), Bland-Altman percentage bias and limits of agreement

From: Abdominal volume computed tomography assessment of body composition in dogs

Hounsfield Threshold Values To Estimate Body Composition (HU)	Regression Equation	r²	Gradient [95% CI]	y-intercept [95% CI]	r_c [95% CI]	Percentage Difference in Mass [Limits of Agreement] (%)
Total DXA Mass
−250/1500	y = 3.41x + 0.09	0.985	3.21 to 3.61	−1.39 to 1.58	0.992 [0.982 to 0.997]	−1.25 [− 14.73 to 12.24]
−250/2000	y = 3.46x + 0.02	0.985	3.26 to 3.65	−1.44 to 1.49	0.993 [0.982 to 0.997]	−1.10 [− 14.17 to 11.98]
− 190/2000	y = 3.49x + 0.01	0.985	3.29 to 3.68	−1.46 to 1.47	0.993 [0.983 to 0.997]	−1.05 [− 14.02 to 11.93]
−190/1000	Excluded^a
− 250/3000	Excluded^b
Total DXA Fat Mass
−250/−5	y = 1.58x + 1.29	0.985	1.49 to 1.67	0.95 to 1.61	0.992 [0.982 to 0.997]	−1.53 [−22.41 to 19.35]
−250/− 25	y = 1.70x + 1.35	0.981	1.59 to 1.81	0.99 to 1.72	0.991 [0.978 to 0.996]	−1.90 [−25.63 to 21.82]
−190/− 30	y = 1.76x + 1.39	0.981	1.65 to 1.87	1.02 to 1.77	0.990 [0.977 to 0.996]	−1.88 [−26.09 to 22.33]
− 135/− 105	y = 5.31x + 1.46	0.948	4.73 to 5.89	0.86 to 2.07	0.974 [0.938 to 0.989]	− 1.35 [−40.28 to 37.58]
Total DXA Lean Mass
0/100	y = 6.30x - 3.81	0.956	5.67 to 6.93	−5.98 to −1.64	0.977 [0.947 to 0.990]	6.06 [−39.28 to 51.41]
−5/150	y = 5.75x - 3.01	0.958	5.19 to 6.31	−5.06 to −0.97	0.978 [0.949 to 0.991]	3.82 [−29.86 to 37.49]
−25/150	y = 5.22x - 2.80	0.972	4.81 to 5.64	−4.44 to −1.16	0.986 [0.966 to 0.994]	3.47 [−26.25 to 33.19]
−29/150	y = 5.14x - 3.04	0.977	4.76 to 5.51	−4.55 to −1.52	0.988 [0.972 to 0.995]	4.87 [−30.43 to 40.17]
−105/150	Excluded^c
Total DXA Bone Mineral Content
152/1000	Excluded^a
150/1500	y = 2.58x + 0.08	0.905	2.19 to 2.97	−0.04 to 0.21	0.950 [0.886 to 0.979]	−0.91 [−26.82 to 25.00]
150/2000	y = 2.64x + 0.08	0.900	2.23 to 3.05	−0.05 to 0.21	0.947 [0.879 to 0.977]	−0.87 [−26.86 to 25.12]
150/3000	Excluded^d

y is the total body tissue mass in kg estimated by the abdominal CT volume
x is the volume in litres calculated by the abdominal CT using the supplied attenuation threshold values
^a Further analyses excluded as manual inspection revealed that cortical bone was excluded from the threshold range
^b Further analyses excluded as values did not differ to − 250/2000HU threshold
^c Further analyses excluded as manual inspection revealed a large volume of fat was included within the threshold range
^d Further analyses excluded as the volumes calculated were exactly the same as the 150/2000HU threshold range

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ISSN: 1746-6148

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