Establishment and validation of a computer-assisted colonic polyp localization system based on deep learning

Table 1 Performance of lesion detection and localization

	Lesions	Sensitivity, %	Specificity, %	PPV, %	NPV, %
Overall	1412	95.0 (93.7-96.0)	99.1 (98.9-99.3)	93.7 (92.3-94.9)	99.3 (99.1-99.4)
Pathology
Non-adenomatous polyps	487	93.4 (90.8-95.4)	99.1 (98.9-99.3)	83.5 (80.0-86.5)	99.7 (99.5-99.8)
Adenomatous polyps	640	95.2 (93.1-96.6)	99.1 (98.9-99.3)	87.1 (84.4-89.5)	99.7 (99.5-99.8)
Adenocarcinomas	285	97.2 (94.3-98.7)	99.1 (98.9-99.3)	75.5 (70.7-79.7)	99.9 (99.8-100.0)
Size
≤ 5 mm	713	94.1 (92.1-95.7)	99.1 (98.9-99.3)	88.2 (85.6-95.3)	99.6 (99.4-99.7)
6-9 mm	396	95.2 (92.5-97.0)	99.1 (98.9-99.3)	80.7 (76.8-84.1)	99.8 (99.7-99.9)
≥ 10 mm	303	96.7 (93.8-98.3)	99.1 (98.9-99.3)	76.5 (71.9-80.6)	99.9 (99.8-99.9)
Paris classification
Ip	180	96.0 (91.8-98.3)	99.1 (98.9-99.3)	65.8 (59.7-71.4)	99.9 (99.8-1.00)
Is	581	96.1 (94.0-97.4)	99.1 (98.9-99.3)	86.1 (83.2-88.6)	99.8 (99.6-99.8)
IIa	525	92.6 (89.9-94.6)	99.1 (98.9-99.3)	84.4 (81.1-87.2)	99.6 (99.5-99.7)
IIb	30	100.0 (85.9-100.0)	99.1 (98.9-99.3)	25.0 (17.7-33.9)	100.0 (99.9-100.0)
IIc	2	100.0 (19.8-100.0)	99.1 (98.9-99.3)	2.2 (0.4-8.4)	100.0 (99.9-100.0)
III	32	96.9 (82.0-99.8)	99.1 (98.9-99.3)	25.6 (18.3-34.5)	100.0 (99.9-100.0)
Unclassified	62	96.8 (87.8-99.4)	99.1 (98.9-99.3)	40.0 (32.2-48.3)	100.0 (99.9-100.0)

PPV: Positive predictive value; NPV: Negative predictive value.

Table 2 Potential causes of false negatives and false positives

Causes of false negatives	No. of images, n (%)	Causes of false positives1	No. of images, n (%)
Test dataset
Fecal fluid/bubble	17 (24)	Folds	18 (19)
Reflections of light	15 (21)	Reflections of light	17 (18)
Difficult angle	13 (19)	Fecal fluid/bubble	16 (17)
Shadow	8 (11)	Colonic valve	11 (12)
Fuzzy image	6 (9)	Ileocecal valve	7 (7)
Color of background	2 (3)	Fuzzy image	5 (5)
Far distance	2 (3)	Others2	11 (12)
Unclassified	7 (10)	Unclassified	10 (11)
Validation in clinical colonoscopy
Shadow	1 (33.3)	Folds3	276 (59.0)
Difficult angle	1 (33.3)	Reflections of light	89 (19.0)
Depressed lesion	1 (33.3)	Fecal fluid/bubble	43 (9.2)
		Normal structures4	46 (9.8)
		Other lesions5	14 (3.0)

¹Twelve lesions were considered to be missed by senior colonoscopists on colonoscopy.

²Others included color change (3), anus (3), lesions under the mucous (2), melanosis coli (1), and bloodstain (1).

³Sixteen folds were caused by suction.

⁴Normal structures included vessels (20), ileocecal valve (12), anus (8), and lymphoid follicle (6).

⁵Other lesions included ulcers (7), cysts under the mucous (4), and diverticulum (3).

Table 3 Polyp detection between colonoscopists and colonoscopists + computer-assisted detection

	Colonoscopists		Colonoscopists + CADe		P value
PDR, %	45.9		48.3		0.06
SSR, %	3.83		4.78		0.50
CRSR, %	9.09		11.5		0.06
Number of polyps, mean ± SD	0.82 ± 1.20		0.90 ± 1.25		< 0.001
Pathology
Non-adenomatous	0.52 ± 0.94		0.58 ± 1.00		0.01
Adenomatous	0.30 ± 0.62		0.32 ± 0.64		0.025
Age
< 50	0.45 ± 0.70		0.51 ± 0.77		0.03
≥ 50	1.12 ± 1.42		1.22 ± 1.47		0.002
Sex
Male	0.96 ± 1.28		1.05 ± 1.36		0.005
Female	0.66 ± 1.07		0.72 ± 1.11		0.01
Location
Proximal	0.35 ± 0.69		0.39 ± 0.76		0.01
Distal	0.46 ± 0.89		0.51 ± 0.90		0.003
Size
≥ 10 mm	0.06 ± 0.28		0.06 ± 0.28		1
6-9 mm	0.18 ± 0.52		0.19 ± 0.52		0.32
≤ 5 mm	0.57 ± 0.95		0.65 ± 1.00		< 0.001
Morphology
Flat	0.67 ± 1.03		0.74 ± 1.08		0.001
Subpedunculated	0.11 ± 0.42		0.12 ± 0.42		0.16
Pedunculated	0.03 ± 0.21		0.03 ± 0.21		1
Indications
Screening	0.76 ± 1.15		0.85 ± 1.21		0.03
Surveillance	1.19 ± 1.42		1.33 ± 1.53		0.03
Diagnosis	0.70 ± 1.10		0.75 ± 1.13		0.03
Colonoscopes
CF-Q290	0.78 ± 1.09		0.87 ± 1.17		< 0.001
CF-Q260	1.04 ± 1.58		1.15 ± 1.56		0.08
CF-Q240	0.83 ± 1.64		0.83 ± 1.64		1
Experience
> 3000	1.24 ± 1.48		1.24 ± 1.48		1
1000-3000	0.79 ± 1.16		0.91 ± 1.26		0.003
< 1000	0.54 ± 0.92		0.62 ± 0.99		0.03
BBPS
< 6	0.59 ± 1.19		0.62 ± 1.19		0.32
≥ 6	0.87 ± 1.19		0.96 ± 1.26		< 0.001
Withdrawal time
< 6 min	0.52 ± 0.97		0.54 ± 0.98		0.16
≥ 6 min	1.13 ± 1.33		1.27 ± 1.39		0.001

CADe: Computer-assisted detection; BBPS: Boston bowel preparation score; PDR: Polyp detection rate; SSR: Sessile serrated adenoma/polyp detection rate; CRSR: Clinical serrated polyp detection rate.

Table 4 Adenoma detection between colonoscopists and colonoscopists + computer-assisted detection

	Colonoscopists		Colonoscopists + CADe		P value
ADR, %	22.0		23.9		0.13
Number of adenomas, mean ± SD
	0.30 ± 0.62		0.32 ± 0.64		0.025
Age
< 50	0.14 ± 0.40		0.15 ± 0.41		0.32
≥ 50	0.43 ± 0.67		0.46 ± 0.69		0.045
Sex
Male	0.38 ± 0.70		0.41 ± 0.73		0.045
Female	0.21 ± 0.48		0.22 ± 0.48		0.32
Location
Proximal	0.12 ± 0.38		0.13 ± 0.39		0.16
Distal	0.17 ± 0.46		0.19 ± 0.47		0.08
Size
≥ 10 mm	0.06 ± 0.28		0.06 ± 0.28		1
6-9 mm	0.11 ± 0.36		0.11 ± 0.36		1
≤ 5 mm	0.12 ± 0.38		0.15 ± 0.42		0.025
Morphology
Flat	0.20 ± 0.47		0.21 ± 0.50		0.045
Subpedunculated	0.07 ± 0.27		0.07 ± 0.28		0.32
Pedunculated	0.03 ± 0.21		0.03 ± 0.21		1
Indications
Screening	0.29 ± 0.65		0.33 ± 0.66		0.08
Surveillance	0.43 ± 0.67		0.45 ± 0.67		0.32
Diagnosis	0.25 ± 0.56		0.26 ± 0.59		0.32
Colonoscopes
CF-Q290	0.31 ± 0.63		0.34 ± 0.65		0.025
CF-Q260	0.23 ± 0.51		0.23 ± 0.51		1
CF-Q240	0.25 ± 0.62		0.25 ± 0.62		1
Experience
> 3000	0.5 ± 0.72		0.5 ± 0.72		1
1000-3000	0.24 ± 0.59		0.27 ± 0.60		0.08
< 1000	0.23 ± 0.53		0.26 ± 0.60		0.16
BBPS
< 6	0.19 ± 0.46		0.19 ± 0.46		1
≥ 6	0.32 ± 0.64		0.35 ± 0.66		0.025
Withdrawal time
< 6 min	0.22 ± 0.57		0.22 ± 0.60		0.32
≥ 6 min	0.38 ± 0.65		0.42 ± 0.65		0.045

CADe: Computer-assisted detection; BBPS: Boston bowel preparation score; ADR: Adenoma detection rate.