CT guided thoracic biopsy

Dr Balint Botz ◉ and Dr Jeremy Jones ◉ et al.

CT guided thoracic biopsy is usually performed for the diagnosis of suspicious lung, pleural or mediastinal lesions. It can be performed as an outpatient procedure where patient monitoring and complications support are available. A small percentage of lung and pleural biopsies may be performed under ultrasound guidance in specific circumstances.

Interventional procedures like thoracic biopsy require special attention to coagulation indices. There are widely divergent opinions about the safe values of these indices for percutaneous biopsies. The values suggested below were considered based on the literature review, whose references are cited below:

complete blood count (CBC)
- platelet > 50000/mm³ (some institutions determine other values between 50000-100000/mm³) ²
coagulation profile
- international normalized ratio (INR) ≤ 1.5 ²
- normal prothrombin time (PT), partial thromboplastin time (PTT)
- some studies showed that having a normal INR or prothrombin time is no reassurance that the patient will not bleed after the procedure ³

Pre-procedure evaluation

Review the diagnostic CT and other relevant imaging first (e.g. PET/CT) to clarify the lesion that is requested to be biopsied. Consideration of the various factors, that influence suitability and degree of risk should be reviewed, including the site and size of the nodule/mass and its relationship to structures that must be avoided ³:

vessels
bleb
bullae
central bronchi
fissures (it is important to minimize the number of pleural surfaces crossed)

Remember, with cavitating lesions the needle must be targeted to the periphery.

For lung lesions, be aware of the postobstructive atelectasis commonly with large central lesions. FDG PET/CT is superior to CT in differentiating between tumor and postobstructive atelectasis and, therefore, essential in those cases to avoid false-negative biopsies ⁸.

Positioning

The patient can be positioned prone, supine or laterally (decubitus) depending on the location of the lesion and their respiratory function. Many of these patients will have an underlying respiratory disease and may be unable to lie completely flat. Some advocate ^{ref required} the patient is best-positioned decubitus with the lesion inferior:

limits respiratory motion
minimizes local aeration; eliminates pneumothoraces
comfortable

Biopsy

a radiopaque grid or skin marker should be utilized to focus the optimal access point then, after preliminary images, this point is marked with a pen
make antisepsis and anesthesia with lidocaine as per the institution's protocol
a skin orifice is made using a scalpel blade
the biopsy needle is introduced as previous planning
activate biopsy gun

Post-procedure care

A period of 'bed-rest' is advised as well as regular observations for some hours after the procedure. The observation period should allow an ample opportunity to identify and treat a potential complication in a timely manner to prevent a serious or catastrophic outcome; it could vary from each institution protocol.

Often, post-procedural x-rays are performed, usually at four hours post biopsy.

There is a growing trend for ambulatory lung biopsy, in which case the patient has the procedure performed as an outpatient without admission to hospital.⁷

Complications

pneumothorax
- most common
- the reported rate of pneumothorax varies widely from 8-64% ⁶
alveolar hemorrhage: may be seen in ~10% (range 5-16.9%)
- hemoptysis: occurs in 1-5% of patients ⁴
air embolism
- can be venous or systemic
- systemic air embolism occurs in up to 0.2% of patients ⁵