Automatic segmentation of cardiac substructures from noncontrast CT images: accurate enough for dosimetric analysis?

Figures & data

Figure 1. Average time needed to modify contours of 11 cardiac substructures per patient for the first 10 patients (clear bars) and for the second 10 patients (solid bars). Error bars represent one standard deviation. LA: left atrium; LV: left ventricle; RA: right atrium; RV: right ventricle; SVC: superior vena cava; IVC: inferior vena cava; PA: pulmonary artery; PV: pulmonary vein; DA: descending aorta; AA: ascending aorta.

Figure 2. Comparison of auto-segmented contours (solid lines) and modified contours (colorwash) for patients (a) and (b) in the axial, sagittal and coronal views. LA: left atrium; LV: left ventricle; RA: right atrium; RV: right ventricle; SVC: superior vena cava; IVC: inferior vena cava; PA: pulmonary artery; PV: pulmonary vein; DA: descending aorta; AA: ascending aorta.

Figure 3. Dose-volume histogram analyses of modified contours (solid lines) are compared with auto-segmented contours (dotted lines) for the two patients (a) and (b) shown in Figure 2. Both patients were treated with passive scattering proton beam therapy. LA: left atrium; LV: left ventricle; RA, right atrium; RV: right ventricle; SVC: superior vena cava; IVC: inferior vena cava; PA: pulmonary artery; PV: pulmonary vein; DA: descending aorta; AA: ascending aorta.

Table 1. Comparison of modified contours versus auto-segmented contours of 11 cardiac substructures.

	Dice similarity coefficient		Mean surface distance (mm)
	Mean ± SD	Range (min, max)	Mean ± SD	Range (min, max)
Heart	0.95 ± 0.04	(0.91, 0.98)	2.1 ± 1.8	(0.9, 3.8)
Left atrium	0.89 ± 0.05	(0.82, 0.97)	1.8 ± 0.7	(0.7, 3.1)
Left ventricle	0.91 ± 0.06	(0.76, 0.97)	2.2 ± 1.8	(0.7, 5.6)
Right atrium	0.86 ± 0.12	(0.72, 0.94)	2.3 ± 2.2	(1.0, 4.0)
Right ventricle	0.87 ± 0.10	(0.65, 0.96)	2.7 ± 2.2	(0.8, 6.1)
Superior vena cava	0.84 ± 0.14	(0.46, 0.98)	1.7 ± 1.3	(0.3, 4.2)
Inferior vena cava	0.78 ± 0.15	(0.53, 0.93)	2.9 ± 5.1	(0.9, 6.3)
Pulmonary artery	0.86 ± 0.05	(0.77, 0.93)	2.2 ± 0.7	(1.0, 3.2)
Pulmonary vein	0.73 ± 0.08	(0.58, 0.90)	2.0 ± 0.7	(0.8, 3.3)
Descending aorta	0.92 ± 0.04	(0.84, 0.99)	1.3 ± 0.6	(0.3, 2.5)
Ascending aorta	0.92 ± 0.06	(0.80, 0.97)	1.4 ± 0.8	(0.6, 2.8)

The reported range values are from data within the 95% confidence interval of mean surface distance.

SD: standard deviation.

Table 2. Dosimetric comparability of modified contours versus auto-segmented contours.

Structures and dosimetric variables	Modified contours Mean ± SD	Auto-segmented contours Mean ± SD	Correlation coefficients^a	p values^b
Heart Dmean (Gy)	10.81 ± 7.78	10.85 ± 7.84	0.984	.86
V30 (%)	13 ± 11	14 ± 11	0.983	.89
Left atrium Dmean (Gy)	20.71 ± 16.21	20.81 ± 16.07	0.991	.66
Left ventricle Dmean (Gy)	4.02 ± 7.11	4.02 ± 7.12	0.994	.33
Right atrium Dmean (Gy)	9.97 ± 10.14	10.83 ± 10.58	0.951	.11
Right ventricle Dmean (Gy)	5.03 ± 6.15	5.02 ± 6.08	0.973	.24
Superior vena cava Dmax (Gy)	74.04 ± 17.06	74.19 ± 17.04	0.936	.14
Inferior vena cava Dmax (Gy)	6.97 ± 15.84	7.91 ± 16.74	0.856	.20
Pulmonary artery Dmax (Gy)	80.75 ± 7.60	80.39 ± 7.47	0.930	.08
Pulmonary vein Dmax (Gy)	78.11 ± 13.24	76.44 ± 14.23	0.791	.01
Descending aorta Dmax (Gy)	63.41 ± 21.38	62.41 ± 21.68	0.956	.18
Ascending aorta Dmax (Gy)	10.81 ± 7.78	10.85 ± 7.84	0.992	.86

^aFrom Pearson’s correlation coefficient (normally distributed data) or Spearman’s rank correlation coefficient (non-normally distributed data).

^bFrom paired Student’s t tests (normally distributed data) or Wilcoxon signed-rank test (non-normally distributed data).

SD: standard deviation; V30: percentage volume receiving dose ≥30 Gy.