Nominal logistic regression analysis of variables determining needle visibility in ultrasound images – a full factorial cadaver study

Table 2 Nominal logistic regression for needle tip visibility

Term	Estimate	Std Error	ChiSquare	Prob > ChiSq	Lower 95%	Upper 95%
Intercept	3.73	0.23	266.56	< 0.0001*	3.29	4.19
tissue[cadaver 1]	-2.02	0.29	48.73	< 0.0001*	-2.60	-1.47
tissue[cadaver 2]	-0.79	0.25	10.04	0.0015*	-1.29	-0.31
tissue[cadaver 3]	-1.68	0.28	37.23	< 0.0001*	-2.23	-1.15
tissue[cadaver 4]	-0.01	0.24	0.00	0.98	-0.48	0.46
tissue[cadaver 5]	-0.01	0.24	0.00	0.98	-0.48	0.46
tissue[cadaver 6]	0.74	0.24	9.69	0.0019*	0.27	1.20
tissue[cadaver 7]	0.98	0.24	16.99	< 0.0001*	0.51	1.44
tissue[cadaver 8]	1.74	0.24	51.55	< 0.0001*	1.27	2.22
tissue[cadaver 9]	0.68	0.24	8.16	0.0043*	0.21	1.14
needle[SonoPlex Stim Facet]	0.14	0.24	0.33	0.57	-0.34	0.61
needle[SonoPlex Stim Sprotte]	0.58	0.24	5.93	0.0149*	0.11	1.05
needle[SonoTAP Facet]	0.58	0.24	5.93	0.0149*	0.11	1.05
needle[SpinoStar BallPen]	-0.46	0.25	3.39	0.07	-0.95	0.02
needle[SpinoStar PencilPoint]	0.52	0.24	4.72	0.0299*	0.05	0.99
needle[SpinoStar Standard Facet]	0.07	0.24	0.09	0.76	-0.40	0.55
needle[StimuPlex D 15°]	-0.12	0.24	0.25	0.62	-0.60	0.35
needle[StimuPlex D 30°]	-0.67	0.25	6.97	0.0083*	-1.17	-0.18
needle[StimuPlex Ultra]	-0.19	0.24	0.59	0.44	-0.67	0.29
bevel orientation[down]	0.84	0.12	50.25	< 0.0001*	0.61	1.07
bevel orientation[side]	-0.61	0.12	26.42	< 0.0001*	-0.85	-0.38
insertion angle (degree)	-0.18	0.01	367.89	< 0.0001*	-0.20	-0.16

Nominal logistic regression for needle tip visibility. Confidence limits are likelihood-based. For log odds of good/poor. Statistically significant results are asterisked

ISSN: 1471-2253