CT guided adrenal biopsy
CT guided adrenal biopsy is usually performed for the diagnosis of indeterminate adrenal nodules or tumours. This procedure has declined in recent years due to improvements in, and validation of, non-invasive CT and MR techniques that can now diagnose benign adrenal lesions with a high degree of confidence 1, 3.
US is also an option for guidance but is less used nowadays. The choice of CT or US guidance was made by the radiologist.
- indeterminate adrenal nodules or tumors
The contraindications must be considered individually in each case. Adrenal or retroperitoneal nodules with high suspicion of pheochromocytoma must be approach cautiously, and if a biopsy is really necessary, consider anesthesiology assistance for blood pressure control 2.
Overall, the most important contraindication are:
- uncooperative patient
- patient inability to cooperate with breathing instruction or suspend respiration (because of the proximity of the adrenal gland to the diaphragm)
- lack of safe access
- uncorrectable bleeding diathesis (abnormal coagulation indices)
Laboratory parameters for a safe procedure
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:
- 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
Review the diagnostic CT and other relevant imaging first (e.g. MRI and PET/CT) to clarify the lesion that is requested to be biopsied. Make sure that previously dedicated adrenal CT and chemical shift MRI protocols were made to evaluate adrenal masses for characteristics specific to adrenal adenomas 3.
The patient can be positioned prone, on semi-prone or on lateral position over CT table. Lateral decubitus position, with the ipsilateral side down, reduces diaphragmatic excursion. Time should be taken to communicate to the patient that maintaining this position is of the utmost importance.
- 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 anaesthesia with lidocaine as the institution's protocol.
- a skin incision is made using a scalpel blade.
- biopsy needle is introduced as previous planning.
- activate biopsy gun.
'Bed-rest' is advised as well as regular observations for four hours (pulse, BP, SpO2). The observation period should allow an ample opportunity to identify and treat a potential complication promptly to prevent a severe or catastrophic outcome; it varies per each institution protocol.
The most frequent complications following adrenal biopsy are haemorrhage and pneumothorax 1.
- 1. Sharma KV, Venkatesan AM, Swerdlow D et-al. Image-guided adrenal and renal biopsy. Tech Vasc Interv Radiol. 2010;13 (2): 100-9. doi:10.1053/j.tvir.2010.02.005 - Free text at pubmed - Pubmed citation
- 2. Walker TG. Interventional Procedures. Lippincott Williams & Wilkins. (2012) ISBN:1931884862. Read it at Google Books - Find it at Amazon
- 3. Paulsen SD, Nghiem HV, Korobkin M et-al. Changing role of imaging-guided percutaneous biopsy of adrenal masses: evaluation of 50 adrenal biopsies. AJR Am J Roentgenol. 2004;182 (4): 1033-7. doi:10.2214/ajr.182.4.1821033 - Pubmed citation