Ultra-low-dose chest computed tomography with model-based iterative reconstruction in the analysis of solid pulmonary nodules: A prospective study

Table 1 Comparison of nodule identification

Identified nodules	Index SDCT	Study SDCT	ULDCT
Solid nodules	94	98	100
Ground glass opacities	5	4	5
Calcified granulomas	10	11	14
Part solid nodules	4	3	3
Total	113	116	122

Comparison of nodule identification between the index standard dose computed tomography (SDCT), study SDCT and ultra-low dose computed tomography (ULDCT) chest imaging protocols. This table demonstrates minimal variability between protocols with ULDCT identifying slightly more solid pulmonary nodules than the SDCT. This discrepancy did not reach statistical significance. SDCT: Standard dose computed tomography; ULDCT: Ultra-low dose computed tomography.

Table 2 Noise and signal-to-noise ratio

Level	10 mm ROI	Noise (HU)			SNR
		ULDCT	SDCT	P value	ULDCT	SDCT	P value
Aortic arch	Aortic lumen	22.28 ± 3.6	21.06 ± 2.9	0.149	2.86 ± 0.8	1.53 ± 0.3	< 0.001
	Paraspinal muscles	20.86 ± 3.6	27.29 ± 4	< 0.001	2.84 ± 0.7	1.89 ± 0.4	< 0.001
Carina	Aortic lumen	23.8 ± 12.4	22.98 ± 4.2	0.359	2.63 ± 0.9	1.57 ± 0.6	< 0.001
	Paraspinal muscles	22.33 ± 4.4	28.28 ± 4.9	< 0.001	2.35 ± 1.1	1.72 ± 0.5	< 0.001
Max. cardiac diameter	Aortic lumen	23.14 ± 7.9	27.7 ± 12.9	0.061	2.14 ± 0.9	1.17 ± 0.6	< 0.001
	Paraspinal muscles	23.44 ± 3.2	23.37 ± 4	0.472	1.66 ± 0.6	1.61 ± 0.6	0.318

Bold face P value indicates statistical significance.

Comparison of objective quantitative measures of image noise and signal-to-noise ratio at three levels from the ultra-low dose computed tomography (ULDCT) with model-based iterative reconstruction and standard dose computed tomography chest protocols. Overall, there is a statistically significant increase in signal to noise ratio in the ULDCT imaging protocol. HU: Hounsfield units, SNR: Signal to noise ratio; ROI: Region of interest; ULDCT: Ultra-low dose computed tomography; SDCT: Standard dose computed tomography.