During the study period, 141 patients underwent transbronchial cryobiopsy using the two-scope technique for PPLs. Of them, cryobiopsy could not be completed in two cases because the tip of the cryoprobe could not be passed to the target lesion. The remaining 139 patients were enrolled and analyzed; a summary of patients’ characteristics are shown in Table 1. The median (range) size was 25.8 (8.7–72.7) mm. Most of the PPLs were located in the right upper lobe/left upper segment (50.4%) and at the outer area (61.8%). Lesions appearing on CT as solid nodules and as GGNs were seen at rates of 74.1% and 25.9%, respectively. Moreover, 20.1% had respiratory comorbidities (11.5% COPD, 4.3% ILD, and 4.3% bronchial asthma), and 3.6% received preoperative bridging anticoagulation therapy.
Table 1. Baseline characteristics of patients
Variable
|
N = 139 (100%)
|
Age, y
|
72 (20 - 88)
|
Male
|
88 (63.3)
|
Body height, cm
|
159.8 (140.0 - 182.6)
|
Body mass index (kg/m2)
|
22.6 (14.4 - 34.4)
|
Diameter of the lesion, mm
|
25.8 (8.7 - 72.7)
|
Related bronchial generation into the PPL, generations
|
5 (3 - 8)
|
Lobar position
|
|
Right upper lobe/left upper segment
|
70 (50.4)
|
Right middle/left lingula
|
17 (12.2)
|
Right lower/left lower
|
52 (37.4)
|
Location area
|
|
Outer area
|
86 (61.8)
|
Inner area
|
53 (38.1)
|
Lesion appearance on CT
|
|
Solid nodule
|
103 (74.1)
|
GGN
|
36 (25.9)
|
Bronchus sign on CT
|
|
Positive
|
104 (74.8)
|
Negative
|
35 (25.2)
|
Bronchoscope type for Biopsy
|
|
Thin scope
|
91 (65.5)
|
Thick scope
|
48 (34.5)
|
Respiratory comorbidities
|
|
Chronic obstructive pulmonary disease
|
16 (11.5)
|
Interstitial lung disease
|
6 (4.3)
|
Bronchial asthma
|
6 (4.3)
|
Use of bridging anticoagulation therapy
|
5 (3.6)
|
Coagulation profile
|
|
PT-INR
|
0.97 (0.87 - 1.17)
|
PTT, s
|
25.9 (20.0 - 37.2)
|
Thrombocytes ( × 103/μL)
|
239 (113 - 524)
|
Data are presented as median (range) or n (%) values.
Abbreviations: PPL peripheral pulmonary lesion, GGN ground-glass nodule, PT-INR prothrombin time international normalized ratio, PTT partial thromboplastin time
The results of bronchoscopy are shown in Table 2. The median (range) procedure time was 28.2 (9.9–55.5) minutes, and the overall diagnostic yield was 89.9%. Figure 2 shows a representative case of successful transbronchial cryobiopsy using the technique for primary lung cancer.
Table 2. Results of bronchoscopy
|
N = 139
|
Procedure time, min
|
28.2 (9.9 - 55.5)
|
Bronchial generation of bronchoscope inserted, generations
|
4 (2 - 7)
|
EBUS images
|
|
Within
|
52 (37.4)
|
Adjacent to
|
83 (59.7)
|
Invisible
|
4 (2.9)
|
Total diagnostic yield
|
125 (89.9%)
|
Data are presented as median (range) or n (%) values.
Abbreviations: EBUS endobronchial ultrasound
Regarding complications, conventional biopsies were not associated with any complications (Table 3). Although mild and moderate bleeding occurred in 42.4% and 18.0% of the patients, respectively, there were no cases of severe or life-threatening bleeding. Of the cases with moderate bleeding, five patients (3.6%) required thrombin instillation. The hemostatic bronchoscope entirely controlled all moderate bleeding episodes without requiring any other intervention. Cryobiopsy caused pneumothorax in two patients (1.4%), both of whom required thoracic drainage, an asthma attack in one patient (0.7%), and hypoxemia requiring oxygen inhalation for several minutes in three patients (2.2%). Of the three patients with hypoxemia, two were overlapped and caused by moderate bleeding, and the other was due to an asthma attack. There were no cases of pneumonia, lung abscesses, respiratory failure, or other severe complications.
Table 3. Complications during cryobiopsy using a two-scope technique for PPLs (N = 139)
Complication
|
Forceps biopsy
|
Cryobiopsy
|
Pneumothorax
|
0
|
2 (1.4%)
|
Bleeding
|
|
|
Mild
|
0
|
59 (42.4%)
|
Moderate
|
0
|
25 (18.0%)
|
Severe/life-threatening
|
0
|
0 (0%)
|
Asthma attack
|
0
|
1 (0.7%)
|
Hypoxemia
|
0
|
3 (2.2%)
|
Data are presented as n (%).
Abbreviation: PPLs peripheral pulmonary lesions
The clinical factors associated with clinically significant bleeding (moderate, severe, and life-threatening) with cryobiopsy are shown in Table 4. In univariable analyses, the ground-glass feature of the lesion was a significant factor for clinically significant bleeding (47.2% vs. 7.8%, P < 0.001). Sample size over 15 mm2 also tended to have a higher bleeding rate, but there was no significant difference (27.8% vs. 14.6%, P = 0.084). In multivariable analysis, only the ground-glass feature of the lesion had a significant effect (OR: 9.30, 95% CI: 3.40–25.40, P < 0.001) on the clinically significant bleeding rate compared to a solid feature.
Table 4. Logistic regression analysis of clinical factors for clinically significant bleeding occurring with transbronchial cryobiopsy
Variable
|
Univariable analysis
|
Multivariable analysis
|
Incidence rate (%)
|
P value
|
OR (95% CI)
|
P value
|
Age, y
|
|
|
|
|
≤70
|
8/57 (14.0)
|
0.37
|
|
|
>70
|
17/82 (20.7)
|
|
|
|
Sex
|
|
|
|
|
Male
|
13/88 (14.8)
|
0.25
|
|
|
Female
|
12/51 (23.5)
|
|
|
|
Body height, cm
|
|
|
|
|
≤170
|
24/121 (19.8)
|
0.20
|
2.58 (0.29 -23.30)
|
0.40
|
>170
|
1/18 (5.6)
|
|
|
|
Body mass index, kg/m2
|
|
|
|
|
≤25
|
22/103 (21.4)
|
0.13
|
2.63 (0.62 - 11.10)
|
0.19
|
>25
|
3/36 (8.3)
|
|
|
|
Diameter of the lesion, mm
|
|
|
|
|
≤20
|
10/47 (21.3)
|
0.49
|
|
|
>20
|
15/92 (16.3)
|
|
|
|
Lobar position
|
|
|
|
|
Right upper lobe/left upper segment
|
13/70 (18.6)
|
1
|
|
|
Right middle/left lingula
|
3/17 (17.6)
|
|
|
|
Lower
|
9/52 (17.3)
|
|
|
|
Location area
|
|
|
|
|
Inner area
|
9/53 (17.0)
|
1
|
|
|
Outer area
|
16/86 (18.6)
|
|
|
|
Lesion appearance on CT
|
|
|
|
|
GGN
|
17/36 (47.2)
|
<0.001
|
9.30 (3.40 - 25.40)
|
<0.001
|
Solid nodule
|
8/103 (7.8)
|
|
|
|
Bronchus sign
|
|
|
|
|
Positive
|
18/104 (17.3)
|
0.8
|
|
|
Negative
|
7/35 (20.0)
|
|
|
|
R-EBUS image
|
|
|
|
|
Within
|
7/52 (13.5)
|
0.41
|
|
|
Adjacent to
|
17/83 (20.5)
|
|
|
|
Invisible
|
1/4 (25.0)
|
|
|
|
Chronic obstructive pulmonary disease
|
|
|
|
|
Present
|
2/16 (12.5)
|
0.74
|
|
|
Absent
|
23/123 (18.7)
|
|
|
|
Interstitial lung disease
|
|
|
|
|
Present
|
1/6 (16.7)
|
1
|
|
|
Absent
|
24/133 (18.0)
|
|
|
|
Bronchial asthma
|
|
|
|
|
Present
|
1/6 (16.7)
|
1
|
|
|
Absent
|
24/133 (18.0)
|
|
|
|
Using bridging anticoagulation therapy
|
|
|
|
|
Present
|
1/5 (20.0)
|
1
|
|
|
Absent
|
24/134 (17.9)
|
|
|
|
Cryoprobe size, mm
|
|
|
|
|
1.9
|
24/129 (18.6)
|
0.69
|
|
|
2.4
|
1/10 (10.0)
|
|
|
|
Number of cryobiopsies taken
|
|
|
|
|
1 biopsy
|
24/120 (20.0)
|
0.20
|
0.29 (0.032 - 2.69)
|
0.28
|
≥ 2 biopsies
|
1/19 (5.3)
|
|
|
|
Freezing time of cryobiopsy, s
|
|
|
|
|
≤5
|
12/59 (20.3)
|
0.66
|
|
|
>5
|
13/80 (16.3)
|
|
|
|
Sample size, mm2
|
|
|
|
|
≤15
|
15/103 (14.6)
|
0.084
|
0.5 (0.17 -1.46)
|
0.21
|
>15
|
10/36 (27.8)
|
|
|
|
Abbreviations: OR odds ratio, CT computed tomography, GGN ground-glass nodule, R-EBUS radial endobronchial ultrasound
Table 5 presents the final histological diagnoses and diagnostic yields of each biopsy technique. Most of the PPLs were finally diagnosed as adenocarcinoma (61.2%). The diagnostic yields of conventional biopsy and cryobiopsy were 76.3% and 81.3%, respectively (P = 0.28). Of them, 8.6% (12 cases) were diagnosable only by conventional biopsy, and 13.7% (19 cases) were diagnosable only by cryobiopsy. When each biopsy technique was combined, the total diagnostic yield was 89.9%, which was significantly higher than conventional biopsy alone (P < 0.001). In the 14 nondiagnostic cases, the diagnosis was established by surgery in six patients, repeat bronchoscopy in three patients, and CT-guided needle biopsy in one patient. The remaining four were clinically suspected to have lung cancer but were being followed-up on CT without surgery at the patients’ request.
Table 5. Histological diagnoses and diagnostic yield
|
n
|
Conventional biopsy
|
Cryobiopsy
|
Total yield
|
P value
|
Malignant
|
|
|
|
|
|
Adenocarcinoma
|
85
|
69/85
|
71/85
|
80/85
|
|
Minimally invasive adenocarcinoma
|
1
|
0/1
|
1/1
|
1/1
|
|
Adenocarcinoma in situ
|
2
|
0/2
|
1/2
|
1/2
|
|
Adenosquamous carcinoma lung
|
1
|
1/1
|
1/1
|
1/1
|
|
Non-small cell carcinoma
|
1
|
0/1
|
1/1
|
1/1
|
|
Squamous cell carcinoma
|
21
|
17/21
|
17/21
|
19/21
|
|
Small cell lung carcinoma
|
6
|
6/6
|
6/6
|
6/6
|
|
Pleomorphic carcinoma
|
3
|
2/3
|
2/3
|
3/3
|
|
Large cell neuroendocrine carcinoma
|
5
|
4/5
|
4/5
|
4/5
|
|
Metastatic tumor
|
2
|
1/2
|
1/2
|
1/2
|
|
Benign
|
|
|
|
|
|
Screlosing hemangioma
|
1
|
0/1
|
1/1
|
1/1
|
|
Organizing pneumonia
|
1
|
1/1
|
1/1
|
1/1
|
|
Lung abscess
|
1
|
1/1
|
1/1
|
1/1
|
|
Nontuberculous mycobacteria
|
2
|
2/2
|
2/2
|
2/2
|
|
Chronic inflammation
|
2
|
1/2
|
2/2
|
2/2
|
|
Cryptococcus
|
1
|
1/1
|
1/1
|
1/1
|
|
Unknown*
|
4
|
0/4
|
0/4
|
0/4
|
|
Total
|
139
|
106/139 (76.3%)
|
113/139 (81.3%)
|
125/139 (89.9%)
|
0.28
|
*These 4 cases are being followed-up by CT.