Computed tomography-guided microwave ablation for right middle lobe pulmonary nodules: a retrospective, single-center, case-control study

Figures & data

Figure 1. Flowchart illustrating patient selection criteria.

Table 1. Baseline characteristics of patients and pulmonary nodules compared between the RML and non-RML groups.

Characteristics	RML group	Non-RML group	p value
Number of patients	71	142
Number of sessions	71	142
Age (years), mean ± SD	60.2 ± 11.8	61.8 ± 10.9	0.318^a
Age (years), n (%)			0.379
<65	43 (60.6)	77 (54.2)
≥65	28 (39.4)	65 (45.8)
Sex, n (%)			0.099
Male	40 (56.3)	63 (44.4)
Female	31 (43.7)	79 (55.6)
Nodule size (mm), mean ± SD	12 ± 0.6	13 ± 0.6	0.125^a
Nodule size, n (%)			0.415
≤10 mm	36 (50.7)	63 (44.4)
>10, ≤20 mm	28 (39.4)	56 (39.4)
>20, ≤30 mm	7 (9.9)	23 (16.2)
Nodule density, n (%)			0.684
Pure GGN	33 (46.5)	71 (50)
Mixed GGN	16 (22.5)	35 (24.6)
Solid nodules	22 (31.0)	36 (25.4)
Synchronous biopsy, n (%)			1.000
Yes	39 (54.9)	78 (54.9)
No	32 (45.1)	64 (45.1)
Pathology, n (%)			0.847^b
No#	26 (36.6)	60 (42.3)
AIS	16 (22.5)	25 (17.6)
MIA	9 (12.7)	19 (13.4)
IA	17 (23.9)	34 (23.9)
SCC	3 (4.2)	4 (2.8)
Distance to RML edge, n (%)			0.759
≤10 mm	46 (64.8)	95 (66.9)
>10 mm	25 (35.2)	47 (33.1)
Penetration of interlobar fissure, n (%)			<0.001
Yes	16 (22.5)	7 (4.9)
No	55 (77.5)	135 (95.1)
Lesion displacement, n (%)			<0.001
Yes	15 (21.1)	7 (4.9)
No	56 (78.9)	135 (95.1)

RML: right middle lobe; GGN: ground-glass nodule; AIS: adenocarcinoma in situ; IA: invasive adenocarcinoma; MIA:minimally invasive adenocarcinoma; SCC: squamous cell carcinoma.

^aTwo independent samples t-test.

^bFisher’s exact test.

^cNo, patients with high-risk GGNs that persisted for a minimum of six months during follow-up but lacked histological confirmation.

Table 2. Complications and post-ablation hospital stay compared between the RML and non-RML groups.

Complications	RML group	Non-RML group	p value
Major complications, n (%)
Pneumothorax	34 (47.9)	28 (19.7)	<0.001
Pleural effusion	3 (4.2)	7 (4.9)	1.000^b
Hemorrhage	2 (2.8)	3 (2.1)	1.000^b
Infection	3 (4.2)	2 (1.4)	0.336^b
Minor complications, n (%)
Pneumothorax	19 (26.8)	16 (11.3)	0.004
Pleural effusion	21 (29.6)	31 (21.8)	0.215
Hemorrhage	3 (4.2)	7 (4.9)	1.000^b
Chest pain	5 (7.0)	6 (4.2)	0.512^b
Procedure time (min), mean ± SD	51.7 ± 17.6	35.3 ± 11.7	<0.001
Hospital stays (day), mean ± SD	4.7 ± 2.2	2.8 ± 1.4	<0.001

RML, right middle lobe.

^bFisher’s exact test.

Figure 2. A female, 55-year-old patient with GGN-like lung cancer in the RML underwent MWA. (A) A mixed GGN located in the RML with a diameter of 12 mm. (B) An antenna was inserted into the tumor. (C) The lesion was covered by ground-glass opacity, and a small amount of pneumothorax was observed immediately post-ablation. (D) The lesion involuted at 1-month post-ablation. (E) The lesion gradually involuted at 12-months post-ablation. (F) The lesion involuted into a band at 36-months post-ablation.

Figure 3. A male, 49-year-old patient with GGN-like lung cancer in the RML underwent MWA. (A) A mixed GGN located in the RML with a diameter of 11 mm. (B) An antenna was inserted into the tumor. (C) A small amount of pneumothorax occurred immediately after MWA. (D) The lesion was covered by ground-glass opacity, displaying a “fried egg” sign, and the pneumothorax volume did not increase. (E) The lesion gradually involuted at 6-months post-ablation. (F) The lesion involuted into a fibrous cord at 14-months post-ablation.

Figure 4. A female, 65-year-old patient with GGN-like lung cancer in the RML underwent MWA. (A) A mixed GGN located in the RML with a diameter of 17 mm. (B) An antenna was inserted into the tumor through the interlobar fissure. A large amount of pneumothorax occurred during the procedure, causing tumor displacement. (C) Continuous negative-pressure chest drainage was performed. (D) After negative-pressure aspiration, the procedure was continued. (E) The lesion was covered by ground-glass opacity, displaying a “fried egg” sign, and the amount of pneumothorax and subcutaneous emphysema did not increase at 72 h after MWA. (F) The lesion gradually involuted at 1 month after MWA. (G) The lesion gradually involuted at 10 months after MWA. (H) The lesion gradually involuted into a fibrous scar at 25 months after MWA.

Table 3. Univariate and multivariate conditional logistic regression analysis of risk factors for pneumothorax.

Variables	Univariate analysis		Multivariate analysis
	OR (95% CI)	p	OR (95% CI)	p
Age (≥65 vs. <65)	1.430 (0.829, 2.467)	0.198
Sex (male vs. female)	1.473 (0.857, 2.532)	0.161
Nodule size
>10, ≤20 mm vs. ≤10 mm	1.068 (0.594, 1.921)	0.825
>20, ≤30 mm vs. ≤10 mm	2.036 (0.886, 4.678)	0.094
Nodule density
(mixed GGN vs. pure GGN)	0.656 (0.326, 1.320)	0.237
(Solid nodule vs. pure GGN)	0.925 (0.483, 1.774)	0.816
Synchronous lung biopsy (yes vs. no)	0.611 (0.352, 1.062)	0.081
Pathology
AIS vs. No^a	1.028 (0.479, 2.205)	0.944
MIA vs. No^a	1.039 (0.434, 2.491)	0.931
IA vs. No^a	1.218 (0.602, 2.464)	0.582
SCC vs. No^a	2.141 (0.451, 10.178)	0.338
Distance to RML edge (>10 mm vs. ≤10 mm)	1.108 (0.627, 1.958)	0.725
Penetration of interlobar fissure (yes vs. no)	3.076 (1.209, 7.824)	0.018	1.669 (0.590, 4.723)	0.334
Lesion displacement (yes vs. no)	2.848 (1.111, 7.305)	0.029	1.577 (0.551, 4.514)	0.396
Procedure time	1.013 (0.996, 1.030)	0.148
Nodule location (RML vs. Non-RML)	6.558 (3.450, 12.464)	<0.001	5.705 (2.921, 11.144)	<0.001

RML: right middle lobe; GGN: ground-glass nodule; AIS: adenocarcinoma in situ; IA: invasive adenocarcinoma; MIA: minimally invasive adenocarcinoma; SCC: squamous cell carcinoma.

^aNo, patients with high-risk GGNs that persisted for a minimum of six months during follow-up but lacked histological confirmation.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author, Xin Ye. The data are not publicly available due to their containing information that could compromise the privacy of research participants.