Research Article

CT-Guided Lung Biopsies Performed with A 16 Gauge Needle and Non-Coaxial Technique: Preliminary Experience with Operator Learning Curve Analysis

Andrea Contegiacomo, Marco Chiappetta, Anna Rita Scrofani, Ernesto Punzi, Nico Attempati, Maria Teresa Dismissal, Luigi Natale, Stefano Margaritora and Riccardo Manfredi

Fondazione Policlinico Universitario A. Gemelli IRCCS
Fondazione Policlinico A. Gemelli IRCCS - Università Cattolica Sacro Cuore

Published Date: 17/08/2021.

*Corresponding author: Andrea Contegiacomo, Department of Diagnostic Imaging, Oncological
Radiotherapy and Hematology, A. Gemelli University Hospital Foundation IRCCS, Largo A. Gemelli 8,
00168, Rome, Italy

DOI: 10.51931/OAJCS.2021.02.000036


Rational and objectives: To assess the diagnostic performance and safety of lung biopsies performed under computed tomography guidance (CTLB) with non-coaxial technique and a 16 Gauge aspiration needle, with a special focus on the operator learning curve.

Materials and Methods: Retrospective observational analysis of 120 CTLB performed with a 16-gauge needle and a non-coaxial technique (study period: January 2017 – April 2020). Patient-related, lesion-related, procedural-related variables and histological results were recorded for each procedure. Study population was divided into two groups based on when the procedures were performed (group A: January 2017 –October 2018; group B: November 2018 – April 2020). Mean procedural time, diagnostic performance and complication rate were compared between the two groups. Appropriate tests were applied for inferential statistical analysis.

Results: Overall sensitivity, specificity, and diagnostic accuracy were 90.2 %, 100.0 %, and 90.8 % respectively. Operator learning curve showed a significant improvement of procedural time, diagnostic accuracy, and sensitivity in group B vs group A (sensitivity: 98.2 % vs 83.5 %; specificity: 100.0 % vs 100.0 %; diagnostic accuracy: 98.3 % vs 83.3%). Complication rate was similar between group A and B. Lesser lesion diameter (p < 0.001) and the presence of emphysema along the needle path (p < 0.001), were associated with increased complication rate, in particular of pneumothorax (p=0.001). Extended contact surface between the lesion and the pleura (p=0.001) resulted a protective factor from procedural complications.

Conclusion: The use of the 16G needles seems a feasible and effective option especially with clinical practice over time.

Keywords: Needle biopsy, CT-guided biopsy, Interventional Oncology, Interventional Radiology, Lung Biopsy Learning Curve.


Lung biopsy performed under computed tomography guidance (CTLB) is an established diagnostic tool to obtain histological diagnosis of pulmonary lesions of unknown origin [1]. The recent development of targeted and immunological therapies for lung cancer increased the need to collect adequate material to achieve the correct diagnosis and to define the molecular profile of the neoplasms in each patient [2]. Coaxial technique is frequently used by interventionalists to increase the amount of tissue obtained during CTLB but the risk of pneumothorax, bleeding and/or fatal air embolism is higher in comparison with non-coaxial technique [3,4]; on the other hand, diagnostic yield of non- coaxial technique has been reported to be lower [4]. The association of larger needles with non-coaxial technique could be an effective compromise between diagnostic performance and risk of complications, but there is lack of evidence about the use of 16 Gauge (G) needles in CTLB practice [5]. The present study reports a preliminary experience on CTLB performed using a 16 G needle in association to non-coaxial, focusing on procedural outcome and the operator learning curve.

Materials and Methods

All CTLB performed with non-coaxial technique and a 16 G needle, between March 2017 and April 2020, were retrospectively included. All the procedures were performed by an interventional radiologist without experience in CTLB performed with 16 G needle and non-coaxial technique. The study was approved by the Institutional Review Board and the requirement for written informed consent was waived due to the retrospective nature of the study. All patients signed an informed consent to the procedure at the time of examination.

Biopsy Technique

For each CTLB, images from diagnostic CT and/or PET-CT (PET, Positron Emission Tomography) examinations were reviewed in order to decide patient's decubitus for the procedure. Orthogonal scanograms were obtained for lesion localization. A CT scan was performed at the lesion level and skin markers were used to plan the best needle path. After local anesthesia, a 16 G manual aspiration needle (TSK, Surecut, Japan) was advanced into the lesion and a single specimen was obtained under CT-guidance. A final CT scan was performed immediately after the procedure for the identification of intra-procedural complications (Figure 1).

Data collection and variables definition

Patient-related (age and sex), lesion-related (lesion size, CT appearance, PET-CT appearance, lesion location, pleural contact) and procedural-related (patient position, presence of emphysema, parenchymal needle path, procedural time, complications, and final diagnosis) variables were obtained from electronic medical records and radiological images from our database. Lesion related variables were defined by two radiologists in consensus. Lesion maximal diameter was measured on CT axial images with the lung window [6].

Lesion CT appearance was classified as solid or not solid, with or without cavitation, in accordance with the Fleischner society guidelines [7]. Positron Emission Tomography (PET) appearance of the lesions was distinguished in up-taking, up-taking with central photopenic area and not up-taking. Parenchymal needle path was measured from the pleural surface to the entry point into the lesion: when necessary, CT multiplanar reconstructions were used to unravel needle trajectory; when the needle trajectory did not across the lung parenchyma, parenchymal needle path was considered absent. Measurement of the lesion pleural contact was obtained at the level of the largest surface of contact between the lesion and the pleura (Figure 2). Procedural time was retrieved from CT images: first CT image after scanograms was considered the start point of the procedure, the last image of the final CT scan was considered as the end of the procedure.

Regarding complications, pneumothorax and parenchymal bleeding were considered minor complications when clinical irrelevant. Pneumothorax requiring percutaneous drainage and prolonged hospitalization (>2 days), hemorrhage with associated hemoptysis, air systemic embolism and death were considered major complications [8].

Histopathological results of the biopsy samples were compared with definitive histopathological diagnoses obtained from surgical specimens (when lesion surgical excision was performed) or obtained by other minimally invasive procedures, such as bronchoscopy, otherwise considering imaging follow-up. The biopsy results were considered true positive or true negative if CTLB malignant or benign results were in accordance with the final malignant or benign diagnoses respectively; otherwise, results were considered false positive (malignant result at CTLB not confirmed) or false negative (benign result at CTLB with final malignant diagnosis at surgical excision or malignant evolution at imaging follow-up). The study population was divided into two groups of equal size according to the date of execution of the procedure for the operator learning curve analysis: the first 60 patients, whose procedures were performed from March 2017 to October 2018, were enrolled in group A; the remaining 60 patients (November 2018 – April 2020) were assigned to group B. A descriptive and inferential analysis of procedural time, diagnostic performance and complication rate was performed on the overall study population and between the two groups.

Figure 1: Procedural steps. 61-year-old woman with a 27 mm nodule of the right lower lobe. Pre-procedural localization of the lesion is obtained by markers (arrowheads) placement on the patient. (A) and the drawing of a reference tattoo on the patient's skin (not shown). After subcutaneous local anesthesia (B) the biopsy needle is advanced across the pleura and within the lesion to perform tissue sampling (C). Final CT scan shows minimal parenchymal bleeding (arrow) along the needle path (D).

Figure 2: Pleural contact extent. 58-year-old woman with a right lower lobe solid nodule of 23 mm in largest diameter. Images analysis for the evaluation of the maximal pleural contact extension involved all the axial images including the lesion (A-C). A maximal 18 mm surface of contact with the parietal pleura (black line in B) was reported; to note the minimal pleural retraction (A,C) suggesting the presence of tumor infiltration and/or adhesions.

CT: Computed Tomography

Figure 3: Procedures’ selection flow chart according to inclusion criteria.

Figure 4: False negative results. 75-year-old man. CT axial images show a suspect 6 mm lesion in the upper left lobe (A) with intense metabolic activity on PET-CT imaging scans (B). Percutaneous CT lung biopsy result was inconclusive as a consequence of poor material (C). After multidisciplinary evaluation a 3-months CT follow-up was decided and performed (D) showing persistence and growth (8 mm) of the lesion. Final surgical diagnosis: lung primitive malignancy (squamous adenocarcinoma).

Figure 5: Operator learning curve descriptive analysis. Charts report sensitivity (a), diagnostic accuracy (b) and complication rate. (c) trends during the study period. Black lines express the trend value of each variable for 60 patients over time (mobile trend); data are reported as percentages. Red lines express the percentage value of each variable in the overall study population.

Statistical Analysis

Statistical analysis was performed with a dedicated software (SPSS 22, IBM). Continuous variables with normal distribution were reported as mean value ± standard deviation. Student’s t-test or one-way ANOVA were adopted to assess significant differences, as appropriate; correlation between continuous variables normally distributed was investigated with Pearson’s linear correlation. For continuous variables without normal distribution Mann-Whitney U test was employed for inferential statistics. For nominal and ordinal variables, the chi-square or Fisher exact test were applied, as appropriate. A p-value < 0.05 was considered as statistically significant.

Table 1: Patients-related and lesions-related variables.

Pt: Patients; CT: Computed Tomography; PET: Positron Emission Tomography; NSCLC: Non-Small Cell Lung Cancer; SCLC: Small Cell Lung Cancer.

*Chi-square test.

** Student's t-test.


A total of 1564 consecutive CTLB were performed in the period March 2017 – April 2020; among these, 120 CTLB performed on 120 patients matched with the inclusion criteria and were finally included (Figure 3). Patient-related and lesion-related variables of the entire study population and of groups A and B are reported in Table 1. Group A and group B did not show significant differences in the variables analyzed. The overall sensitivity, specificity, and diagnostic accuracy were 90.2 %, 100.0 %, and 90.8 % respectively (Table 2). A false negative result occurred in 11/120 (9.2%) CTLB; among these, eight patients showed a high lesion uptake at PET-CT examination with final malignant diagnosis after surgery (Figure 4), three patients showed volumetric increase at imaging follow-up.

The presence of a parenchymal needle path, especially in the presence of emphysema, was strongly associated with increased complication rate (p < 0.001), in particular with pneumothorax (p < 0.001); the same result was observed for lesions with a lesser diameter (p < 0.001). An extended contact surface between the lesion and the pleura resulted a protective factor from procedural complications (p < 0.001). All the remaining results are shown in Table 3. A significant improvement of the procedural time (23.2 ± 6.45 minutes in group A vs 20.1 ± 4.8 minutes in group B; p =0.006), diagnostic accuracy (83.3 % vs 98.3 %; p = 0.004), and sensitivity (82.5 % vs 98.2 %; p = 0.005) was observed in group B in respect to group A; specificity was 100% in both groups and the complication rate was comparable between groups A and B (p = 0.201). Descriptive analysis of diagnostic indicators, procedural time and complication trends is shown in Figure 5.

Table 2: Inferential statistics.

CT: Computed Tomography; PET: Positron Emission Tomography; NSCLC: Non-Small Cell Lung Cancer; SCLC: Small Cell Lung Cancer.

*Chi-square test.

**Fisher exact Test

** Student's t-test.

Table 3: Procedure-related variables.

Y/N, presence/absence.

* Chi-square test

** Student's t test

*** Mann-Whitney U test

**** Fisher's exact test

***** Pearson's correlation

****** One-way ANOVA


The present study reports a preliminary experience on CTLB performed with a non-coaxial technique and a 16 G needle, with a particular focus on procedural outcome and operator learning curve. Although CTLB procedural outcome has been extensively studied over years, operator learning curve on CTLB is still an unexplored ground. Su et al [9] previously investigated learning curve for lung biopsies performed on a cone-beam CT system in association with a virtual navigation software, but a comparable analysis of lung biopsies performed with conventional CT systems has never been investigated before.

Learning curve analysis showed procedural streamlining over time as suggested by the reduction of mean procedural time in group B compared to group A. This effect could be explained by the progressive experience-related optimization of the procedural steps, such as a more “fluid” placement of the needle within the lesion, and a fewer number of CT scans required for lesion targeting. A positive shift was evident from group A to group B in terms of sensitivity, specificity and diagnostic accuracy; this improvement was predominantly influenced by the marked reduction of false negative results in group B (1 vs 10 of group A). It is our opinion that these results are the consequence of at least two different factors: (1) an increased amount of adequate material due to an improved use of the needle; (2) a refined analysis of the diagnostic CT / PET-CT images before the procedure, with a more accurate selection of the target portion of the lesions; a more effective needle insertion within the lesion during the procedure; both factors could be traceable back to an increased operator experience over time.

The overall complication rate of study population was 49.57% (59/120 patients), with operative management occurred in 11/120 (9.16%) patients, all treated with chest tube placement for a non-limiting pneumothorax, and with a median hospitalization of 3 days. This data are in agreement with those reported by other authors with smaller needles sizes [10,11], suggesting that the use of non-coaxial technique and 16 G needles is basically safe; however, about 50% of patients had procedural complications (predominantly minor complications), without an improvement of complication rate over time.

Our experience confirms that a smaller diameter of the lesion [12] [13] and the presence of emphysema along the parenchymal needle path [22, 23] are predisposing factors for complications during CTLB. On the contrary, the presence of pleural contact on CT images resulted as a protecting factor from the onset of complications (p = 0.012) [24] with a negative correlation between complication risk and contact surface extent (p < 0.001); a possible explanation of this result could be the presence of inflammatory adhesions or tumor infiltration of the pleura that nailed the lung against the thoracic wall during the needle passage. Comparative studies with post-biopsy surgical findings could better clarify this aspect. This study has some undeniable limitations: the sample size is relatively small with single-arm design, however, the number of procedures included was adequate for a valuable learning curve analysis and we have reason to think that a longer observation period and a greater number of procedures would have flattened the distance between groups A and B in terms of procedural time and diagnostic yield, interfering with the learning curve analysis; furthermore, the inclusion of a second arm would not have added information on the operator learning curve. Secondly, a specific analysis of the quality of pathological specimens was not possible in our population due to the retrospective nature of the study.

In the era of personalized medicine, the goal of CTLB is to provide an adequate amount of material to achieve an accurate diagnosis and, in cases of malignancy, to allow the molecular characterization of the lesion [14]. However, the use of CTLB should take into account the following critical aspects: diagnostic accuracy is extremely variable, ranging from 71% to 97% [6, 15], and procedural complications are relatively common, up to 62% [16] , with pneumothorax being the forerunner [10, 16]. Biopsy technique and needle caliper are essential elements that may affect procedural outcome: the use of a coaxial (needle in needle) technique could improve the diagnostic accuracy if compared to non-coaxial approach [4] but arises the risk of pneumothorax, perilesional bleeding and/or fatal complications [3, 4, 10]. On the other hand, non-coaxial technique is usually performed with small needles reducing chances to obtain both diagnosis and lesion molecular profile [4, 17, 18]. According to our preliminary results, non-coaxial technique in association with 16 G needles seems a feasible approach for CTLB with satisfactory outcomes, comparable with those previously reported for CTLB [19-21]. Practice over time improves procedural length and operator diagnostic performance, maintaining an adequate complication rate.

 Declaration of Interest

All the Authors declare to have no conflict of interest.


  1. Yang W, Sun W, Li Q (2015) Diagnostic accuracy of CT-guided transthoracic needle biopsy for solitary pulmonary nodules. PLoS One 10(6): e0131373.
  2. Salgia R (2016) Mutation testing for directing upfront targeted therapy and post-progression combination therapy strategies in lung adenocarcinoma. Expert Review of Molecular Diagnostics 16(7): 737-749.
  3. Lang D, Reinelt V, Horner A (2018) Complications of CT-guided transthoracic lung biopsy: a short report on current literature and a case of systemic air embolism. Wien Klin Wochenschr 130(7–8): 288–292.
  4. Nour-Eldin NEA, Alsubhi M, Emam A (2016) Pneumothorax complicating coaxial and non-coaxial CT-guided lung biopsy: comparative analysis of determining risk factors and management of pneumothorax in a retrospective review of 650 patients. Cardiovasc Intervent Radiol 39(2): 261–270.
  5. Iezzi R, Larici A, Contegiacomo A (2017) A new score predicting intraprocedural risk in patients undergoing CT-guided percutaneous needle pulmonary biopsy (CATH-score). Eur Rev Med Pharmacol Sci 21(16): 3554-3562.
  6. Uzun Ç, Akkaya Z, Atman ED (2017) Diagnostic accuracy and safety of CT-guided fine needle aspiration biopsy of pulmonary lesions with non-coaxial technique: a single center experience with 442 biopsies. Diagnostic Interv Radiol 23(2):137–143.
  7. Macmahon H, Naidich DP, Goo JM (2017) Guidelines for management of incidental pulmonary nodules. Radiology 284(1): 228-243.
  8. Gupta S, Wallace MJ, Cardella JF, Kundu S, Miller DL, et al. (2010) Quality improvement guidelines for percutaneous needle biopsy. J Vasc Interv Radiol 21(7): 969-975.
  9. Ahn SY, Park CM, Yoon SH, Kim H, Goo JM (2019) Learning Curve of C-Arm Cone-beam Computed Tomography Virtual Navigation-Guided Percutaneous Transthoracic Needle Biopsy. Korean J Radiol 20(5): 844-853.
  10. Heerink WJ, de Bock GH, de Jonge GJ, Groen HJM, Vliegenthart R, et al. (2017) Complication rates of CT- guided transthoracic lung biopsy: meta-analysis. Eur Radiol 27(1): 138-148.
  11. Ocak S, Duplaquet F, Jamart J (2016) Diagnostic Accuracy and Safety of CT-Guided Percutaneous Transthoracic Needle Biopsies: 14-Gauge versus 22-Gauge Needles. J Vasc Interv Radiol 27(5): 674-681.
  12. Chiappetta M, Rosella F, Dall'armi V (2016) CT-guided fine-needle ago-biopsy of pulmonary nodules: predictive factors for diagnosis and pneumothorax occurrence. Radiol Med 121(8): 635-643.
  13. Wallace MJ, Krishnamurthy S, Broemeling LD (2002) CT-guided percutaneous fine-needle aspiration biopsy of small (≥1-cm) pulmonary lesions. Radiology 225(3): 823–828.
  14. Zhang C, Leighl NB, Wu YL, Zhong WZ (2019) Emerging therapies for non-small cell lung cancer. J Hematol Oncol 12(1): 1–24.
  15. Arakawa H, Nakajima Y, Kurihara Y, Niimi H, Ishikawa T (1996) CT-guided transthoracic needle biopsy: a comparison between automated biopsy gun and fine needle aspiration. Brain Lang 51(7): 503–516.
  16. Wu CC, Maher MM, Shepard JAO (2011) Complications of CT-guided percutaneous needle biopsy of the chest: Prevention and management. Am J Roentgenol 196(6): 678–682.
  17. Zhang L, Shi L, Xiao Z, Qiu H, Peng P, et al. (2018) Coaxial technique-promoted diagnostic accuracy of CT-guided percutaneous cutting needle biopsy for small and deep lung lesions. PLoS One 13(2): 1–10.
  18. Hoang NS, Ge BH, Pan LY (2018) Determining the optimal number of core needle biopsy passes for molecular diagnostics. Cardiovasc Intervent Radiol 41(3): 489-495.
  19. Hiraki T, Mimura H, Gobara H (2009) CT fluoroscopy-guided biopsy of 1,000 pulmonary lesions performed with 20-gauge coaxial cutting needles: Diagnostic yield and risk factors for diagnostic failure. Chest 136(6):1612-1617.
  20. Priola AM, Priola SM, Cataldi A (2010) Diagnostic accuracy and complication rate of CT-guided fine needle aspiration biopsy of lung lesions: A study based on the experience of the cytopathologist. Acta radiol 51(5): 527–533.
  21. Takeshita J, Masago K, Kato R (2015) CT-guided fine-needle aspiration and core needle biopsies of pulmonary lesions: a single-center experience with 750 biopsies in Japan. Am J Roentgenol 204(1): 29–34.
  22. Sangha BS, Hague CJ, Jessup J, O’Connor R, Mayo JR (2016) Transthoracic Computed Tomography–Guided Lung Nodule Biopsy: Comparison of Core Needle and Fine Needle Aspiration Techniques. Can Assoc Radiol J 67(3): 284-289.
  23. Lee DS, Bak SH, Jeon YH, Kwon SO, Kim WJ (2019) Perilesional emphysema as a predictor of risk of complications from computed tomography-guided transthoracic lung biopsy. Jpn J Radiol 37(12): 808-816.
  24. Guimarães MD, de Andrade MQ, Da Fonte AC, Benevides G, Chojniak R, et al. (2010) Predictive complication factors for ct-guided fine needle aspiration biopsy of pulmonary lesions. Clinics 65(9): 847–850.

Subscribe to newsletter

© 2020. All rights reserved.