Deep-learning-based object detection of pelvic autonomic nerves during total mesorectal excision

Table 1 Patients baseline characteristics and distribution of pelvic autonomic nerves annotation boxes, mean ± SD/n (%)

Characteristic	Internal cohort (n = 120)	External validation cohort (n = 20)
Gender
Male	68 (56.7)	11 (55.0)
Female	52 (43.3)	9 (45.0)
Age	62.5 ± 10.2	63.1 ± 9.8
BMI (kg/m2)	23.1 ± 2.8	22.8 ± 3.0
UICC-TNM stage
II stage	87 (72.5)	14 (70.0)
III stage	33 (27.5)	6 (30.0)
Histological type
Adenocarcinoma	97 (80.8)	18 (90.0)
Other	23 (19.2)	2 (10.0)
Surgical procedure
Low anterior resection	99 (82.5)	17 (85.0)
Abdominoperineal resection	3 (2.5)	0 (0.0)
Intersphincteric resection	18 (15.0)	3 (15.0)
Intraoperative blood loss (mL), median (interquartile range)	15 (10-20)	12 (8-18)
Operation duration (minute)	256.7 ± 71.4	256.7 ± 71.4
Preoperative neoadjuvant therapy
Received	88 (73.3)	15 (75.0)
Not received	32 (26.7)	5 (25.0)
Annotation box (sum)	5402	930
RIMP	973 (18.0)	140 (15.1)
LIMP	864 (16.0)	157 (16.9)
SHP	216 (4.0)	37 (4.0)
RHN	610 (11.3)	110 (11.8)
LHN	648 (12.0)	114 (12.3)
RPN	820 (15.2)	130 (14.0)
LPN	878 (16.2)	158 (16.9)
RNVB	200 (3.7)	44 (4.7)
LNVB	193 (3.6)	40 (4.3)

BMI: Body mass index; UICC-TNM: Union for International Cancer Control-tumor node metastasis; RIMP: Right inferior mesenteric plexus; LIMP: Left inferior mesenteric plexus; SHP: Superior hypogastric plexus; RHN: Right hypogastric nerve; LHN: Left hypogastric nerve; RPN: Right pelvic nerve; LPN: Left pelvic nerve; RNVB: Right neurovascular bundle; LNVB: Left neurovascular bundle.

Table 2 Comparison of deep learning model performance metrics between merged labels and separate labels

Label	Image	Annotation Box	DL model 1					DL model 2
			Precision	Recall	F1-score	mAP50	mAP50-95	Precision	Recall	F1-score	mAP50	mAP50-95
All	346	521	0.762	0.506	0.608	0.580	0.246	0.839	0.769	0.802	0.873	0.534
IMP	346	183						0.889	0.767	0.824	0.907	0.539
RIMP	346	97	0.764	0.568	0.652	0.606	0.238
LIMP	346	86	0.801	0.635	0.708	0.706	0.291
SHP	346	20	0.763	0.590	0.665	0.656	0.293	0.755	0.721	0.738	0.835	0.527
HN	346	123						0.851	0.704	0.771	0.842	0.520
RHN	346	61	0.777	0.489	0.600	0.550	0.248
LHN	346	62	0.797	0.450	0.575	0.540	0.248
PN	346	157						0.881	0.780	0.827	0.873	0.548
RPN	346	82	0.738	0.407	0.525	0.490	0.216
LPN	346	75	0.635	0.395	0.487	0.469	0.203
NVB	346	38						0.821	0.871	0.845	0.911	0.534
RNVB	346	20	0.755	0.492	0.596	0.592	0.251
LNVB	346	18	0.826	0.527	0.643

Precision = TP/(TP + FP) (TP: True positive, correctly identified autonomic nerve regions; FP: False positive, non-nerve regions misidentified as autonomic nerves). Recall = TP/(TP + FN) (FN: False negative, autonomic nerve regions not detected); F1-score = 2 × (precision × recall)/(precision + recall) (ranges from 0 to 1; a value closer to 1 indicates better overall performance). mAP50 indicate mean average precision across all categories at an intersection over union threshold of 0.5 (average precision is the area under the precision recall curve). mAP50-95 indicate mean average precision values at intersection over union thresholds from 0.5 to 0.95 (10 thresholds in 0.05 increments), evaluating detection robustness across different thresholds. Model 1: Deep learning model with separate labels; Model 2: Deep learning model with merged labels; DL: Deep learning; IMP: Inferior mesenteric plexus; RIMP: Right inferior mesenteric plexus; LIMP: Left inferior mesenteric plexus; SHP: Superior hypogastric plexus; HN: Hypogastric nerve; RHN: Right hypogastric nerve; LHN: Left hypogastric nerve; PN: Pelvic nerve; NVB: Neurovascular bundle; RPN: Right pelvic nerve; LPN: Left pelvic nerve; RNVB: Right neurovascular bundle; LNVB: Left neurovascular bundle.

Table 3 Comparison of recognition rates and missed diagnosis rates for 5 categories of pelvic autonomic nerves among the deep learning model, junior surgeons and senior surgeons, n (%)

Category	Annotation box	Group	Recognized cases	Missed cases	P value
IMP	297	DL model	228 (76.7)	69 (23.3)
		Senior surgeon	222 (74.8)	75 (25.2)	0.682
		Junior surgeon	198 (66.7)	99 (33.3)	0.021
SHP	37	DL model	27 (72.1)	10 (27.9)
		Senior surgeon	26 (70.3)	11 (29.7)	0.895
		Junior surgeon	20 (54.1)	17 (45.9)	0.038
HN	224	DL model	157 (70.4)	67 (29.6)
		Senior surgeon	152 (67.9)	72 (32.1)	0.713
		Junior surgeon	132 (58.9)	92 (41.1)	0.017
PN	288	DL model	222 (77.1)	66 (22.9)
		Senior surgeon	216 (75.0)	72 (25.0)	0.758
		Junior surgeon	192 (66.7)	96 (33.3)	0.024
NVB	84	DL model	73 (87.1)	11 (12.9)
		Senior surgeon	71 (84.5)	13 (15.5)	0.812
		Junior surgeon	62 (73.8)	22 (26.2)	0.041
Sum	930	DL model	707 (76.0)	223 (24.0)
		Senior surgeon	687 (73.9)	243 (26.1)	0.156
		Junior surgeon	604 (64.9)	326 (35.1)	0.001

All P values were compared with the deep learning model group. DL: Deep learning; IMP: Inferior mesenteric plexus; SHP: Superior hypogastric plexus; HN: Hypogastric nerve; PN: Pelvic nerve; NVB: Neurovascular bundle.

Table 4 Comparison of initial recognition and duration of tracking time between the deep learning model and senior surgeon, mean ± SD

Category	Group	Initial recognition time					Tracking duration
		Sample size (n)	Time (seconds)	Delta (95%CI)	t value	P value	Sample size (n)	Time (seconds)	Delta (95%CI)	t value	P value
IMP	DL model	32	2.08 ± 5.91	3.83 (1.03-6.64)	2.749	0.0081	28	199.41 ± 142.40	62.82 (19.94-107.88)	3.026	0.0061
	Senior surgeon	32	5.92 ± 8.59				28	136.59 ± 98.43
SHP	DL model	32	2.15 ± 6.12	3.91 (1.10-6.72)	2.801	0.0071	15	192.75 ± 137.80	59.34 (18.76-101.92)	2.914	0.0071
	Senior surgeon	32	6.06 ± 8.85				15	133.41 ± 95.90
HN	DL model	32	1.97 ± 5.63	3.68 (0.98-6.38)	2.654	0.0091	30	204.17 ± 145.60	64.93 (20.61-111.25)	3.092	0.0051
	Senior surgeon	32	5.65 ± 8.21				30	139.24 ± 100.70
PN	DL model	32	2.12 ± 6.03	3.87 (1.07-6.67)	2.783	0.0081	56	207.32 ± 148.20	66.45 (21.15-113.75)	3.158	0.0041
	Senior surgeon	32	5.99 ± 8.73				56	140.87 ± 101.90
NVB	DL model	32	2.21 ± 6.25	3.98 (1.15-6.81)	2.845	0.0061	20	188.63 ± 134.50	57.21 (17.98-98.44)	2.857	0.0081
	Senior surgeon	32	6.19 ± 9.02				20	131.42 ± 93.80

¹Compared with the senior surgeon group.

CI: Confidence interval; DL: Deep learning; IMP: Inferior mesenteric plexus; SHP: Superior hypogastric plexus; HN: Hypogastric nerve; PN: Pelvic nerve; NVB: Neurovascular bundle.

Table 5 False positive analysis in junior surgeon and deep learning model, n (%)

Classification of false positive recognition	Junior surgeon	DL model	Reduction of false positives
Cord-like fibrous tissue	18	9	9 (50)
Vascular-related structure	14	6	8 (57.14)
Fat-related structure	11	5	6 (54.55)
Peritoneal incision and mesenteric tissue	9	3	6 (66.67)
Surgery-related artifact	8	2	6 (75)
Sum	60	25	35 (58.33)

DL: Deep learning.