Comparison of the Diagnostic Accuracy: US-guided Percutaneous Lung Biopsies vs CT-guided in Peripheral Lung Lesions

Peripherical pulmonary lesions without endobronchial lesions (LPP) are nowadays more and more frequently found in clinical practice, and it's only assumable that this tendency will keep growing in the future, alongside the increasing use of thoracic CT scanning and the proven efficacy in lung cancer screening. Even though most of these lesions are benign, it's still important to be able to identify neoplastic lesions in an early stage.

The gold standard for diagnosis definition is biopsy, which can be performed by four paths: surgery, transbronchial endoscopy (TBB), endobronchial endoscopy (EBB) or percutaneous (TTNA).

Surgical option is the most reliable one in terms of diagnostic yield, at the expense of an increased risk of complications, post-operative recovery in hospital staying and costs, compared with the other three procedures; due to the safety and diagnostic yield of TBB, EBB and TTNA, the surgical approach, just for the purpose of diagnosis, resulted in a secondary choice in the diagnostic flowchart of LPP. In addiction, given the high probability of the benign nature of the LPP, the choice of a less invasive approach in the diagnostic phase is even more reasonable. Even though technology really improved the diagnostic yield of LPP, overall sensibility is around 70-80%, influenced by many factors such as: localization and extension of the lesion, presence of bronchus sign, sampling techniques and procedural errors. The incidence of complications for this type of sampling, mostly presented by pneumothorax, is around 4%.

The TTNA is a largely used procedure for diagnosing LPP and it can be conducted using both a CT guided and an ultrasound guided approach, as long as the lesion is located in direct contact with the thoracic wall. CT scan guide has the perk of giving a more precise view of: densitometric feature of the lesions, their location and the connections with the anatomical structures surrounding them. LPP CT guided TTNA (tTTNA) can reach a diagnostic yield of 98% in case of an experienced operator, where ultrasound guided reaches about 93.4%, only slightly inferior to the prior one. Both tTTNA and ultrasound guided percutaneous transthoracic biopsy (eTTNA) are useful techniques not only for pulmonary parenchymal diseases but also in case of pleural lesions, allowing simultaneous sampling and visualization of the lesions in exam.

Peripheric pleural lesions can also be approached via thoracoscopy (both medical and surgical) with a diagnostic efficiency between 91-95% for malignant lesions and 100% for Tuberculosis-related lesions. However, the high risk of complications after the procedure, the duration of hospitalization post-surgery and the costs, suggest choosing between eTTNA and tTTNA as the very first diagnostic step in pleural lesions as well. Moreover, the diagnostic yield of tTTNA and eTTNA is respectively of 89% and 90%.

Both eTTNA and tTTNA demonstrated a good ability in distinguishing between benign and malignant lesions. In the latter case, collecting a representative enough sample allows the appropriate immunohistochemical phenotyping and genetic sequencing of it, enabling to make targeted therapeutical choices according to the current Guidelines.

Literature suggests that the number of bioptic steps necessary to obtain an adequate diagnostic sample is of three steps, where an upper number of them would increase the risk of complications despite an almost equal diagnostic efficiency. Principal complications of percutaneous sampling, common to both the approaches, are pneumothorax and minor bleeding (not requiring blood transfusion) In literature there are no clear indications about which of these two methods is better in case of lesions touching the pleural surface, therefore approachable with both tTTNA and eTTNA; in everyday clinical practice the choice is mostly driven by the availability of each technique in the Center of expertise. Also, from the literature that could be gathered, there is no prospective comparison between ultrasound-guided and CT-guided needle biopsy of peripheric pulmonary lesion touching the thoracic wall.

Nonetheless, a trial retrospectively analyzed both ultrasound-guided and CT-guided sampling of thoracic lesions touching the wall and it enlightened that the complications rate was minor for the ultrasound-guided approach: respectively 3.3% and 24%. Even more, differently from the tTTNA, eTTNA doesn't expose the patients to any ionizing radiation and it allows to avoid artefacts deriving from respiratory movements and the ribs' interposition.

On this ground of observations, we present the following trial, which would be the first prospective one to compare the diagnostic accuracy between the two approaches (tTTNA and eTTNA) for diagnosing peripheric pulmonary lesions touching the thoracic wall.

The trial's goal is comparing the diagnostic yield of ultrasound-guided vs CT-guided histological sampling of peripheric pulmonary lesions touching the thoracic wall.

All patients must, therefore, have carried out recent blood tests (within one month before the procedure) routine including: complete blood count, international normalized ratio(INR), activated partial thromboplastin time(aPTT), prothrombin time(PT).

When taking charge of the patient, the inclusion and exclusion criteria will be verified. The patient candidate for the procedure signs the informed consent to the study in the presence of the local coordinator or co-investigator. The coordinator or co-investigator will proceed with the randomization (through random numbers generated by a computer) to perform ultrasound-guided or CT-guided sampling, which will be scheduled with the usual technical times of each individual participating Center.

Each patient will be assigned a progressive number/code for anonymization purposes to be used in the electronic Case Report Form(eCRF). The diagnostic procedures will be carried out in the Respiratory Endoscopy and Radiology rooms where TTNAs are usually carried out. The ultrasound investigation will be conducted using the ultrasound machine supplied to the Center involved in the trial and usually used in eTTNA procedures.

The CT scan will be performed using the CT machinery equipped by the Center involved in the trial and usually used for the tTTNA procedures.

Before the procedure, the vital signs of the patient will be noted and each operator will choose the most appropriate position for the sampling, based on the location of the lesion. The thoracic area to biopsy will then be defined and then there will be the setting of the sterile field. In accordance to the guide-lines the patient should not be sedated if possible. At this point, local anesthesia with a maximum of 20ml of 2% lidocaine will be administrated, marking down this time as the time of the beginning of the procedure.

18 Gauge needles will be used to collect the samples, since this size allows a good balancing between risk of complication and diagnostic yield. For each patient, there will be collected a minimum number of one and a maximum number of three bioptic sampling. The sample will be stored and preserved inside specific containers to allow optimal transfer to the Pathology laboratories, based on the directions of the laboratory itself and the usual procedure of the involved Center.

Once the procedure is done, the patient will remain in the involved Center for a period of observation of at least three hours. During this time, the patient will be monitored through vital signs and the occurrence of any complication. After one hour from the procedure, a thoracic X-Ray examination will be taken, preferably in orthostatism, in both inhale and exhale. The management of any possible complication will be carried out as part the singular Center's practice, in agreement with the latest Guide Lines regarding the matter.

In the case of the impossibility of the technical use of the procedure assign to the singular patient by the randomization, the patient will be excluded from the trial and will carry on the diagnostic iter according to the usual clinical practices.

The onset of complications will be registered during the patients' monitoring process, which will last for the three hours following the procedure. All the participant patients will be informed about the possible late-onset complications after the procedure and about the necessity of coming back to the hospital in case of the occurrence of any symptoms, such as dyspnea, chest pain, hemoptysis/bloody sputum.

The anatomopathologist will receive the samples without the indication of the methodic used for the biopsy. The pathologist will, then, pronounce judgment un: 1) adequacy of the samples for the purpose of the diagnosis 2) where indicated, the suitability for a full histological molecular analysis. Once the diagnosis is given, the local coordinator or the co-investigators will communicate the result to the patient as soon as possible, in order to address the patient to the currently most appropriated diagnostic-therapeutic pathway.

The tissue sample will be submitted to the pathologist along with a form containing personal data, anamnesis, clinical suspicion, the sample topography and the trial code. In order to preserve the double-blind criteria in the anatomopathological reporting, all the requests coming from a center will submitted after the name of the local coordinator. The pathologist will report the resulting diagnosis to his center's the coordinator via email and only then it will be possible to move forward to the unblinding. Enrolled patients will be entered in an eCRF file, shared exclusively between the interventional operators. Therefore, the patients will be addressed to the best diagnostic-therapeutic program available at the time, according to the most recent guidelines.