Optimization of the Sensitivity of Histological Diagnosis of Pulmonary Nodules

Optimization of the Sensitivity of Histological Diagnosis of Pulmonary Nodules Using Cryoprobes Versus Standard Biopsy Forceps During Distal Sampling Guided by Mini Radial Ultrasound Probes

In pulmonary oncology, the diagnosis of medium-sized pulmonary nodules (10 to 20 mm), too distal to be reached by standard bronchial fibroscopy but remaining proximal, is difficult.

There are 2 techniques: transthoracic puncture-biopsy under CT scan, usually performed by radiologists, and distal sampling guided by radial ultrasound mini-probe.

The limitations of the last technique could be overcome by the use of cryoprobes for sampling, as they would take more tissue by freezing.

Concerning the interventional pneumology technique, it is performed in two steps: identification of the mass with the mini ultrasound probe and then distal sampling with a small biopsy forceps. Experience shows that there is a significant difference between the identification of the mass, which is fairly conclusive, and the samples, which are much less productive (60% at best), because it is necessary that :

• that the tumor is endo-bronchial,
• that the forceps open sufficiently to take samples by back and forth movements
• but, on the other hand, that the bronchus is not too wide.

The use of cryoprobes would allow to take more tissue by freezing. The target tissue freezes at the tip of the cryoprobe and can be detached by traction. The longer the freezing time, the more tissue is removed.

Various studies of endo-bronchial visible tumor diagnosis have compared these 2 sampling techniques (cryoprobe and conventional biopsy forceps). The cryoextraction technique performed by cryoprobes has a superior diagnostic yield (compared to flexible forceps biopsy) due to large biopsies and superior quality of the biopsied tissue (very few crush artifacts or hematomas; the morphological structure remains intact).

In this context, it seems interesting to compare these 2 techniques but in distal situation, under ultrasound detection with the mini-probes, for tumors not visible in endo-bronchial. The first samples taken in the investigating center by this technique are convincing.

In the framework of this study, in the same operating time and after ultrasound identification of the tumor, biopsies will be performed by conventional forceps (5 samples) and by cryoprobes (3 samples) on the same site. The sequence of use of one or the other technique will be randomly selected. Thus, each patient is his own control.

This first pilot study will explore the feasibility, effectiveness and safety of this procedure. Depending on the results of this comparative study, a second study including more patients will validate this procedure.

Inclusion Criteria:

• Patient with a tumor of any location with a draining bronchus (primary lung cancer or lung metastases)
• Suspected lung nodule(s) with anatomical situation on mid 1/3 CT
• Presence of at least one lung nodule of sufficient size on CT to allow for at least 8 tissue samples
• Male or female aged ≥ 18 years
• Mandatory membership in a health insurance plan
• Patient who has been informed about the study and has signed the informed consent form

Exclusion Criteria:

• Proximal or distal pulmonary nodule(s)
• Pacemaker patient
• Pregnant or nursing women
• Patients under legal protection