Quantitative Emphysema Measurement On Ultra-High-Resolution CT Scans

Figures & data

Table 1 Clinical Characteristics Of The 32 Study Participants

	Mean ± SD	Range
Gender (female:male)	(3:29)	–
Age (years)	71 ± 10	(49 to 88)
Brinkman index	933 ± 505	(300 to 2480)
FVC (L)	3.1 ± 0.8	(1.8 to 4.6)
FEV1 (L)	2.1 ± 0.7	(0.7 to 3.6)
FEV1 (%predicted)	0.78 ± 0.20	(0.30 to 1.13)
FEV1/FVC	0.68 ± 0.13	(0.29 to 0.88)

Abbreviations: FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 s; SD, standard deviation.

Table 2 Measurements Of Emphysematous Lesions Obtained On U-HRCT Scans Versus Conventional HRCT Scans At Different Density Thresholds

CT Indices	Image Mode		P-Value
	U-HRCT	Conventional HRCT
LV (L)	5.25 ± 0.96	5.26 ± 0.96	<0.001
LAV%−950 (%)	8.9 ± 8.8	7.3 ± 8.4	<0.0001
LAV%−960 (%)	5.7 ± 6.5	4.6 ± 6.0	<0.0001
LAV%−970 (%)	3.6 ± 4.6	2.9 ± 4.1	<0.0001

Abbreviations: LV, lung volume; LAV%₋₉₅₀/LAV%₋₉₆₀/LAV%₋₉₇₀, percentage low attenuation volume at thresholds of −950, −960, and −970 Hounsfield units; U-HRCT, ultra-high-resolution computed tomography.

Figure 1 Visualization of lesions of pulmonary emphysema on ultra-high-resolution CT (U-HRCT) and conventional HRCT images. On an U-HRCT image (left), the margins of pulmonary emphysema are more clearly depicted than on a conventional HRCT image (right), particularly the relatively small emphysematous lesions (rectangles).

Figure 2 Ultra-high-resolution CT (U-HRCT) image compared with a conventional HRCT image for the detection of emphysema. At the threshold setting of <−950 Hounsfield units, emphysematous lesions are identified as dark-red areas on axial images. Some of the very small emphysematous lesions, which is clearly identified on the U-HRCT image (left), cannot be seen on the identical conventional HRCT image (right).

Figure 3 Quantitative measurements of lesions of pulmonary emphysema on ultra-high-resolution CT (U-HRCT) and conventional HRCT scans. Red areas are emphysematous lesions identified by the software (<−950 Hounsfield units). In this COPD patient, the percentage low attenuation volume (LAV%) was 32.8% on the U-HRCT scan (left) and 30.7% on the conventional HRCT scan (right).

Figure 4 Comparison of the percentage of low attenuation volume (LAV%) on ultra-high-resolution CT (U-HRCT) and conventional HRCT scan modes using the threshold of −950 Hounsfield units. LAV% on HRCT scans tends to increase on U-HRCT scans.

Table 3 Correlations Between Values For LAV% And Airflow Limitation

Image Mode	LAV% At Different Thresholds	Correlation With FEV1/FVC
		Coefficient (ρ)	P-Value
U-HRCT	LAV%−950	−0.50	<0.01
	LAV%−960	−0.47	<0.01
	LAV%−970	−0.40	<0.05
Conventional HRCT	LAV%−950	−0.49	<0.01
	LAV%−960	−0.43	<0.05
	LAV%−970	−0.35	<0.05

Abbreviations: LAV%₋₉₅₀/LAV%₋₉₆₀/LAV%₋₉₇₀, percentage low attenuation volume at thresholds of −950, −960, and −970 Hounsfield units; U-HRCT, ultra-high-resolution computed tomography; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity.

Figure 5 Correlation between FEV₁/FVC and LAV%₋₉₅₀ (U-HRCT). A significant, negative correlation is observed between LAV%₋₉₅₀ and FEV₁/FVC.

Abbreviations: FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; LAV%₋₉₅₀, percentage low attenuation volume at a threshold of −950 Hounsfield units; U-HRCT, ultra-high-resolution computed tomography.