The Interplay of Time and Angle with the Incidence of Pneumothorax in Computed Tomography-Guided Lung Biopsy

Abstract

Purpose

Pneumothorax remains one of the most common complications of computed tomography (CT)-guided lung biopsy, highlighting the importance of investigating contributing factors. This study assessed the interplay between the needle-pleura angle and the biopsy needle traversal duration (NTD) through the lung parenchyma during CT-guided lung biopsies that resulted in pneumothorax.

Materials and Methods

In this retrospective study, 96 patients underwent CT-guided lung biopsies. The minimum delta (δmin) was calculated as the absolute value of the difference between a 90° angle and the measured angles of the needle with respect to the pleura, and correlations with the occurrence of pneumothorax were analyzed. The NTD was recorded from the moment of needle puncture through the pleura until needle retraction. Patients with pneumothorax were grouped on the basis of NTD: < or > 6 minutes. A multivariate analysis was conducted, comparing four patient groups with and without pneumothorax.

Results

6 out of 96 patients undergoing CT-guided lung biopsies were excluded because of predefined exclusion criteria. 22 patients experienced postprocedural pneumothorax—6/22 patients had δmin > 10° with NTD > 6 minutes, 5/22 had δmin < 10° with NTD < 6 minutes, 2/22 had δmin > 10° with NTD < 6 minutes, and 9/22 had δmin < 10° with NTD > 6 minutes. Overall, 14.7% of patients with δmin < 10° and NTD < 6 minutes experienced pneumothorax compared with 33.3% of patients with δmin > 10° with NTD > 6 minutes.

Conclusion

Optimizing the needle-pleura angle and NTD during a CT-guided lung biopsy can reduce the risk of pneumothorax.

Key Points

• Pneumothorax is the most common complication of lung biopsies.

• Needle angle und needle-traversal duration can affect the incidence of pneumothorax.

• Needle-pleura angle and the needle-traversal duration can reduce the risk of pneumothorax.

Citation Format

• Maalouf N, Abou Mrad M, Benayed R et al. The Interplay of Time and Angle with the Incidence of Pneumothorax in Computed Tomography-Guided Lung Biopsy. Rofo 2025; DOI 10.1055/a-2594-7226

Zusammenfassung

Zielsetzung

Ein Pneumothorax bleibt eine der häufigsten Komplikationen bei computertomografisch (CT)-gesteuerten Lungenbiopsien, was die Bedeutung der Untersuchung beitragender Faktoren unterstreicht. Diese Studie analysierte das Zusammenspiel zwischen dem Nadel-Pleura-Winkel und der Nadel-Traversierungsdauer (NTD) durch das Lungenparenchym während CT-gesteuerter Lungenbiopsien, die zu einem Pneumothorax führten.

Material und Methoden

In dieser retrospektiven Studie unterzogen sich 96 Patienten CT-gesteuerten Lungenbiopsien. Das Minimum-Delta (δmin) wurde als Absolutwert der Differenz zwischen einem 90°-Winkel und den gemessenen Pleurawinkeln berechnet, und Korrelationen mit dem Auftreten eines Pneumothorax wurden analysiert. Die NTD wurde vom Zeitpunkt der Nadelpunktion durch die Pleura bis zum Nadelrückzug erfasst. Patienten mit Pneumothorax wurden basierend auf der NTD in zwei Gruppen eingeteilt: < oder >6 Minuten. Eine mehrfaktorielle Analyse wurde durchgeführt, wobei vier Patientengruppen mit und ohne Pneumothorax verglichen wurden.

Ergebnisse

6 von 96 Patienten, die sich CT-gesteuerten Lungenbiopsien unterzogen, wurden aufgrund vordefinierter Ausschlusskriterien ausgeschlossen. 22 Patienten entwickelten einen postprozeduralen Pneumothorax—6 von 22 Patienten wiesen ein δmin >10° mit einer NTD >6 Minuten auf, 5 von 22 hatten ein δmin <10° mit einer NTD <6 Minuten, 2 von 22 zeigten ein δmin >10° mit einer NTD <6 Minuten, und 9 von 22 hatten ein δmin <10° mit einer NTD >6 Minuten. Insgesamt entwickelten 14,7% der Patienten mit δmin <10° und NTD <6 Minuten einen Pneumothorax, im Vergleich zu 33,3% der Patienten mit δmin >10° und NTD >6 Minuten.

Schlussfolgerung

Die Optimierung des Nadel-Pleura-Winkels und der NTD während einer CT-gesteuerten Lungenbiopsie kann das Risiko für einen Pneumothorax reduzieren.

Kernaussagen

• Ein Pneumothorax ist die häufigste Komplikation bei Lungenbiopsien.

• Nadelwinkel und Nadel-Traversierungsdauer können die Inzidenz eines Pneumothorax beeinflussen.

• Die Optimierung von Nadel-Pleura-Winkel und Nadel-Traversierungsdauer könnte das Pneumothoraxrisiko verringern.

Keywords

pneumothorax - biopsy - thorax

Introduction

Computed tomography (CT)-guided lung biopsy is a common procedure used for the histological and molecular investigation of pulmonary lesions. CT-guided lung biopsy requires local anesthesia, minimal medical personnel, and minimal pre-interventional preparation, contributing to its wide use as a routine clinical examination. This is particularly significant, considering the increasing incidence of cancer and the predicted rise in new cancer cases in the future [1]. Common complications of CT-guided lung biopsy include asymptomatic pneumothorax, which occurs in 15–54% of cases [2] [3] [4] [5] [6] [7] [8], and symptomatic pneumothorax, which requires interventions and chest tube placement in 1.4–16.7% of patients [4] [5] [7] [8] [9]. Numerous factors were reported to influence the risk of pneumothorax [4] [5] [10] [11] [12] [13] [14] [15]. Recently, the needle-pleura angle was shown to play a significant role, with the risk of pneumothorax decreasing as the needle approaches a 90° angle [10] [11] [16] [17]. Investigators studied the effect of the needle traversal duration (NTD), also known as the dwell time, on the risk of pneumothorax and reported it to be an independent risk factor for pneumothorax [18]. This study investigated the correlation between the needle-pleura angle and the NTD through the lung parenchyma during CT-guided lung biopsies, as well as its relationship with the incidence of pneumothorax.

Materials and Methods

Study population

This retrospective analysis included 96 patients who underwent CT-guided lung biopsies between January 2020 and March 2024 (54 males, 42 females, median age: 71 years, age range: 49–90 years) for a histological diagnosis of pulmonary nodules ([Fig. 1]). The exclusion criteria included patients who experienced immediate intraprocedural pneumothorax. In total, six patients were excluded from the study. All patients provided informed consent more than 24 h prior to the intervention. Ethical approval was given by the local ethics committee.

Fig. 1 Flowchart of patients who underwent CT-guided lung biopsy in our department.

Biopsy technique

All interventions were performed by the same interventional radiologist with 15 years of experience using a semiautomatic 18G needle and a 17G trocar, with patients in a prone or supine position. The 18G biopsy needle has a semiautomated Tru-Cut design with a central sharp stylet surrounded by a hollow cylindrical sheath, and this has become a standard tool for diagnostic lung biopsies [19]. The 17G trocar (Möller Medical GmbH, Fulda, Germany) facilitates multiple biopsies of the same pulmonary nodule with only one pleural passage because it acts as a guide for the 18G needle. The angles to the right and left were measured digitally with respect to the patient while the needle was fully in-plane, and the z-axis was consistently regarded as 90°. The minimum delta (δ_min) was calculated as the absolute value of the difference between a 90° angle and the measured angles with respect to the pleura on the right and left sides, and it was correlated with the occurrence of pneumothorax as an intraprocedural or early postprocedural complication ([Fig. 2]). The dwell time of the biopsy needle within the lung parenchyma was recorded from the moment of needle puncture through the pleura until needle retraction. All biopsies were planned and executed to circumvent vessels, bullae, interlobar fissures, and ribs.

Fig. 2 We digitally measured the angles of the needle with respect to the pleura on both the right and left sides. In this case, the measured angle was 90°, resulting in a calculation of 90° – 90° = 0, which gives a δmin of 0.

Measured variables and statistical analysis

The needle-pleura angle and NTD were recorded by the interventional radiologist and evaluated retrospectively. A chest CT control scan was performed at the end of the procedure. Patients with intraprocedural and postprocedural pneumothorax were recorded. Patients with asymptomatic pneumothorax were defined as patients with no symptoms and a pneumothorax of less than 1 cm. Symptomatic patients were those who had a pneumothorax greater than 1 cm on CT and developed progressive symptoms. We conducted a multivariate statistical analysis using Excel version 14.0.4760.1000 (Microsoft Corporation, Redmond, WA, USA). Patients who experienced immediate intraprocedural pneumothorax were excluded from the study. The remaining patients with pneumothorax were grouped according to their NTD: less than or more than 6 minutes. A multivariate analysis was conducted, comparing four patient groups with and without pneumothorax, categorized as follows: δ_min > 10° and NTD > 6 minutes; δ_min < 10° and NTD < 6 minutes; δ_min > 10° and NTD < 6 minutes; and δ_min < 10° and NTD > 6 minutes. We performed the Chi-square test for the final grouping and calculated the p-value. We considered p > 0.05 to be statistically significant.

Results

Between January 2020 and March 2024, our department performed CT-guided lung biopsies on 96 patients. After excluding six patients who developed immediate pneumothorax—one of whom required early termination of the biopsy due to a clinically significant pneumothorax necessitating intervention—the final study cohort consisted of 90 patients. Postprocedural pneumothorax occurred in 22 patients (24.4%), whereas 68 patients (75.6%) did not develop this complication ([Fig. 1]).

Among the patients who experienced pneumothorax, we observed varying combinations of minimum needle-pleura angle (δ_min) and NTD. Six patients had δ_min > 10° with NTD > 6 minutes, and five had δ_min < 10° with NTD < 6 minutes. Two patients had δ_min > 10° and NTD < 6 minutes, while the largest subgroup within the pneumothorax cases, consisting of nine patients, had δ_min < 10° with NTD > 6 minutes ([Fig. 3]).

Fig. 3 Distribution of patients with and without pneumothorax into four categories.

In the group without pneumothorax, we noted a different distribution of these parameters. Most patients (n = 29) had δ_min < 10° with NTD < 6 minutes, 20 had δ_min < 10° with NTD > 6 minutes, 7 had δ_min > 10° with NTD < 6 minutes, and 12 had δ_min > 10° with NTD > 6 minutes ([Fig. 3]).

A noteworthy finding emerged when comparing patients with pneumothorax. In patients with δ_min < 10° and NTD < 6 minutes, the incidence of pneumothorax was 14.7% (5 out of 34 patients). In contrast, patients with δ_min > 10° and NTD > 6 minutes experienced a higher rate of pneumothorax at 33.3% (6 out of 18 patients). This represents a 2.27-times lower risk of pneumothorax for patients with δ_min < 10° and NTD < 6 minutes. A _δmin < 10° significantly impacts the incidence of pneumothorax (p = 0.0023), whereas NTD alone did not demonstrate statistical significance. Additionally, the combination of both factors did not yield statistically significant results with p-value = 0.3587.

There was no significant difference in NTD between patients experiencing asymptomatic pneumothorax and symptomatic pneumothorax requiring drainage.

Discussion

Pneumothorax is still the most common complication of CT-guided lung biopsy [20] [21]. In our study, 22 out of 90 patients experienced pneumothorax (24.4%) after a CT-guided lung biopsy, which is similar to rates reported by other studies [22] [23] [24]: Chakrabarti et al. reported the incidence of pneumothorax was 24% in a study of 134 patients [22], Heyer et al. reported an incidence of 26% in 159 patients [23], and Charig et al. reported an incidence of 25.9% in 150 patients [24]. A higher incidence of pneumothorax was reported in larger-scale studies: 42.3% in 1098 patients [5] and 35% in 6881 patients [21].

Our previous findings suggested a significant correlation between a needle-pleura angle close to 90° and a reduced incidence of pneumothorax [10] [11]. In our latest study of the risk of pneumothorax after CT-guided lung biopsy, 30% of patients with δ_min < 10° experienced pneumothorax compared with 71.8% of patients with δ_min ≥ 10° (p = 0.0023) [10]. Based on our previous work and the significant effect of the needle-pleura angle on the incidence of pneumothorax, this study investigated the effect of NTD in lung parenchyma on the rate of pneumothorax.

The NTD in our study ranged from 2 minutes and 2 seconds to 17 minutes and 25 seconds, with an average of 6 minutes and 13 seconds in the patient group that experienced no pneumothorax. The average NTD for patients who experienced pneumothorax was 8 minutes 20 seconds, 8 minutes 7 seconds for patients with asymptomatic pneumothorax, and 8 minutes 36 seconds for patients experiencing pneumothorax and requiring chest drainage. Since patients who experienced no pneumothorax had an average NTD of 6 minutes, we aimed to show a possible correlation with patients with an NTD longer or shorter than 6 minutes as well as a δmin< or ≥ 10°. These results suggest a potential relationship between the combination of needle pleura angle and needle in time duration. The observed differences in pneumothorax rates among various subgroups indicate that these parameters may play a role in predicting procedural complications.

Our results demonstrate that combining a favorable needle-pleura angle with a short needle traversal duration resulted in a 2.27-times lower chance of pneumothorax. Ko et al. hypothesized that extended dwell times might influence pneumothorax rates by enlarging the pleural puncture site and causing damage to the lung parenchyma related to needle motion during patient respiration. Their research revealed that prolonged dwell times did not correlate with an increased risk of pneumothorax [12]. Validating this latter finding, Ozturk et al., Laurent et al., and Sheikh et al. reported no significant association between extended needle traversal time and pneumothorax risk [9] [13] [17]. These results underscore the multifaceted nature of the factors influencing pneumothorax occurrence in percutaneous lung biopsies.

Patients with immediate pneumothorax were excluded from this study due to the presence of two pleural passages, which did not meet our inclusion criteria. The strengths of this study include a broad age spectrum and the involvement of a single interventional radiologist, which contributes to procedural consistency. However, this investigation was a single-center retrospective study, indicative of a limitation that may affect the generalizability of the findings.

In conclusion, optimizing the needle-pleura angle and NTD during a CT-guided lung biopsy can reduce the risk of pneumothorax.

Clinical relevance of the study

• CT-guided lung biopsies are a common method for obtaining histopathologic samples of pulmonary pathologies.

• Pneumothorax remains the most common complication of CT-guided lung biopsies.

• This article suggests a possible correlation between the needle-pleura angle and the needle traversal duration with respect to reducing the incidence of pneumothorax.

Conflict of Interest

The authors declare that they have no conflict of interest.

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Publication History

Received: 10 November 2024

Accepted after revision: 23 April 2025

Article published online:
23 May 2025