Thermal-assisted visceral pleural dissection to overcome pleural tenting during lung ablation: A technical innovation

INTRODUCTION

Percutaneous thermal ablation is an established minimally invasive treatment option for primary and metastatic lung tumors.^[1] Accurate probe placement within or immediately adjacent to the target lesion is critical to achieving effective ablation margins while minimizing complications. Subpleural and fissural lung lesions, however, present a distinct technical challenge due to the mechanical properties of the visceral pleura.^[2,3]

Visceral pleural tenting occurs when advancement of an ablation probe causes deformation and traction of the pleura without successful penetration, resulting in displacement of the lung parenchyma away from the target lesion. This phenomenon may lead to suboptimal probe positioning, prolonged procedure time, or procedural failure. Commonly employed strategies to mitigate pleural tenting include adjustment of needle trajectory, patient positioning, respiratory control, hydrodissection, and parenchymal buffering. Despite these measures, pleural tenting may persist in select cases.^[4-6]

We describe a novel, operator-initiated technical maneuver using brief, controlled thermal activation of the ablation probe to facilitate dissection through the tented visceral pleura, enabling accurate probe advancement toward the target lesion. This report outlines the technique and presents four cases utilizing different thermal ablation platforms.

METHODS

Procedural setting and technique

All lung thermal ablation procedures were performed in a dedicated interventional CT suite (Siemens Definition Edge©) under general anesthesia. Patients were routinely positioned in a lateral decubitus position contralateral to the target lesion to optimize access and minimize respiratory motion (e.g., left lateral decubitus positioning for right lung lesions). All patients were endotracheally intubated with a double-lumen endotracheal tube, maintained as a fail-safe measure to permit selective lung isolation in the event of significant intraprocedural pulmonary hemorrhage.

Probe advancement was performed exclusively during controlled breath holds at end expiration, a strategy used to reduce diaphragmatic motion and optimize visceral pleural tension to facilitate needle penetration. All intraprocedural CT acquisitions were reconstructed in real time using multiplanar 3D visualization, allowing simultaneous axial, sagittal, and coronal assessment to guide probe trajectory and confirm spatial relationships.

When persistent visceral pleural tenting was encountered during probe advancement [Figure 1], a controlled transient thermal activation technique was employed. Depending on the location of the target lesion, either microwave ablation or cryoablation was used. For microwave ablation, specifically the Varian IntelliBlate© system was utilized, whereas cryoablation was performed using a Boston Scientific IcePearl© cryoablation probe, utilizing the system’s active thaw (“i-thaw”) function. Transient thermal activation was performed during a breath hold (65 Watts for 15 s for the microwave ablation probe and 50°–70° for 15 s for the cryoablation probe, respectively). Successful disruption of the visceral pleura was defined by loss of pleural tenting and forward advancement of the probe tip beyond the pleural interface on immediate post-activation CT imaging, most noticeably appreciated on sagittal reconstructions.

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Figure 1: 76-year-old female with metastatic leiomyosarcoma to the lung. (A) Sagittal view non-contrast computed tomography image demonstrating tenting and traction of the visceral pleura caused by the microwave ablation probe during positioning (blue arrow). The adjacent target lesion is pulling away from the ablation probe (red star). (B) After 15 s of microwave energy delivery at 65 W, controlled disruption of the tented visceral pleura is observed (red arrow), resulting in release of traction and optimal juxtaposition of the probe to the target lesion. PL: Planned Line. N1: Needle 1. Green, orange and purple cursors indicate digital trajectory alignment markers

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Once the ablation probe was positioned in an optimal juxtalesional location [Figure 2], definitive ablation was performed according to standard manufacturer-recommended protocols. The brief transient thermal activation used to facilitate pleural traversal did not alter or subtract from the prescribed ablation time for lesion treatment.

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Figure 2: 72-year-old female with metastatic pancreatic cancer presenting with a solitary lung metastatic lesion. (A) Non-contrast sagittal view computed tomography image demonstrating tenting and traction of the visceral pleura resulting in forward displacement of the target lesion by the cryoablation probe during positioning (blue arrow). (B) Following 15 s of microwave energy delivery using the Boston Scientific i-Thaw© application, controlled disruption of the tented visceral pleura is observed, allowing optimal juxtaposition to the target lesion and subsequent formation of an ice ball (red arrow). Green arrow and cursor: Digital trajectory alignment marker.

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RESULTS

All four patients were adult patients who presented with oligometastatic lung disease and were referred to Interventional Radiology for thermal ablation therapy. In all cases, brief thermal activation enabled controlled traversal of the tented visceral pleura and accurate probe positioning. No pneumothorax or immediate pleural complications were observed on intra and post-procedural CT imaging or subsequent chest radiographs. All patients were discharged after one overnight observation. Follow-up chest CT images at 1, 3, and 6 months demonstrated expected ablation zones changes without evidence of pleuro-bronchial fistula, delayed pneumothorax, or other procedure-related adverse events.

DISCUSSION

Visceral pleural tenting remains a technically challenging and under-described obstacle in percutaneous lung ablation, particularly for subpleural or fissural lesions.^[8] Excessive mechanical force risks uncontrolled pleural rupture or pneumothorax, while alternative techniques such as hydrodissection may not always be feasible or effective.^[9,10]

This technical innovation introduces a controlled, energy-assisted method to facilitate pleural traversal using equipment already available during standard ablation procedures. To the best of our knowledge, intentional, transient thermal activation of an ablation probe to facilitate traversal of a tented visceral pleura during percutaneous lung ablation has not been previously described. Prior approaches to pleural tenting focus on mechanical or positional strategies rather than targeted energy-assisted pleural modification. This report introduces a novel technical innovation that leverages existing ablation platforms to enable controlled pleural dissection and improved access when facing unexpected difficulties in passing the visceral pleura.

The successful use of this maneuver across two different thermal platforms suggests potential applicability beyond a single device type. This report is limited by its anecdotal nature and small sample size, and the absence of complications in these cases should not be interpreted as definitive evidence of safety. Further investigation is needed to better define optimal energy parameters and activation duration, to identify lesion and patient characteristics most suitable for this approach, and to evaluate complication rates in larger patient cohorts. Until such data are available, this technique should be applied cautiously by experienced operators and reserved for situations in which conventional strategies to overcome visceral pleural tenting have been unsuccessful.

CONCLUSION

Brief controlled thermal activation of ablation probes may provide a feasible method to overcome visceral pleural tenting during percutaneous lung ablation. This technique enabled accurate probe placement without observed complications in four different patients. While promising, this approach remains preliminary and warrants further investigation before widespread adoption.