Dr.Suhas BResident (MD Radio-diagnosis)

IntroductionFine needle aspiration (FNA) is a type of minimally-invasive tissue sampling Ultrasound guided biopsy is one form of imaged guided biopsy, typically

performed by a radiologist. It is the most common form of image guided biopsy, offering

convenience and real time dynamic observation with echogenic markers on cannula allowing for precise placement.

Ultrasound-guided biopsy involves the removal of cells from a suspicious area within the body using a thin needle and a syringe.

It can potentially be used to perform a biopsy of any body part, being regularly used to biopsy the kidney, liver, breast and lymph nodes.

If the suspected tumor is in the deeper planes and cannot be seen or felt by the physician, then the patient is asked to get an ultrasound-guided biopsy.

The sample of tissue or fluid then is evaluated in the laboratory to determine your diagnosis.

Indicationsa suspicious solid massa distortion in the structure of the visceraan area of abnormal tissue change

Applications currently include sampling cells in lesions from: thyroid non-thyroid neckbreast liver lymph nodes lungbonegastrointestinal tractMediastinumPancreatic mass

Guidelines for Thyroid biopsyhigh risk history • with suspicious sonographic features: >5 mm• without suspicious sonographic features: >5 mm• with abnormal cervical lymph nodes: all; FNA may be obtained from the lymph

node as well• with microcalcifications: ≥1 cmsolid nodule• hypoechoeic: >1 cm• solid nodule, iso or hyperechoeic: ≥1-1.5 cmmixed cystic-solid nodule • with suspicious sonographic features: ≥1.5-2 cm• without suspicious sonographic features: ≥2 cmspongiform nodule: ≥2 cmpurely cystic: FNA not indicated

Contraindicationsuncooperative patientlack of safe accessuncorrectable bleeding diathesis (abnormal coagulation indices)

Laboratory parameters for a safe procedureComplete blood count: Platelet > 50000/mm3

international normalized ratio (INR) ≤1.5 3

normal prothrombin time (PT), partial thromboplastin time (PTT)

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ProcedurePreprocedural evaluationPatient consent and pre-procedure targeted physical examA pre-procedure targeted ultrasound exam is commonly performed.

Equipment The "fine needle" in an FNA varies depending on the system being

biopsied and the nature of the lesion, but is typically a 22 gauge to 27 gauge needle with a stylet. For ultrasound-guided procedures, the transducer may have a needle guide.

Generally a 3.5 – 5 Mhz transducer is used for biopsy, however a linear/superficial probe is useful in case of neck masses and breast lesions.

1%/2% lidocaine without epinephrineBetadine and spirit swabs50cc and 20cc syringes10 glass slides with teasers for tissue separation

PositioningFor most of the lesions as in case of liver, pancreas, GIT, neck etc., the

patient is positioned in supine or lateral decubitus position with maximum access to the location of the lesion.

For lung or pleural biopsy patient can be either made to sit upright of lie down in lateral decubitus position .

For FNA biopsy from breast, patient is positioned in the dorsal decubitus as for a conventional breast ultrasound exam or in lateral decubitus as it promotes a safer access to the lesion.

Probe Sterilization The transducer must be sterilized before its use by betadine and spirit

swabbing. Ideally a layer of disposable plastic/condom should be placed over it to achieve true sterilization.

Technique The FNA technique will vary depending on the system being targeted

and the nature of the lesion. Techniques common to all procedures include:

local anesthesia with 2% buffered lidocaineMust keep needle in plane of beam (biopsy guide would do this for you)Shortest distance/safest pathwayadvancing the fine needle under imaging guidance until the tip is in the

intended area of biopsy removal of the stylet “Sewing-machine” motion for fine-needle ‘aspirates’ (filling the needle

with the tissue) removal of the needle with appropriate disposition of the cells (e.g. slide

for smear, container for cell block)multiple samples are usually obtained in a sessionSpray aspirates carefully on the slideSmear gently, dry rapidly

Postprocedural careThere is no standardized postprocedure care for FNA. Compression of the

biopsy site with gauze is common to control minor local bleeding. If the lung is biopsied, a post procedure radiograph may be obtained. In case of liver and pancreas biopsy, patient is made to lie in right lateral

and prone positions respectively.A minimum of three hours of bed rest is essential after any biopsy.

ComplicationsComplications are uncommon with appropriate FNA technique, usually

limited to bleeding or infection. Bleeding is more of a concern with deeper abdominal aspirations since direct pressure can rarely be applied.

Pneumothorax is a risk of lung biopsies. Either a postprocedure radiograph or ultrasound may be obtained to look for this complication.

OutcomesFNA success is measured in terms of aspirating a diagnostic amount of

tissue and maintaining patient comfort.

Rates of success in aspirating diagnostic tissue depend on multiple factors, not the least of which include the size of the needle being used, the location of the lesion, and the type of lesion being biopsied. Larger bore "fine" needles capture more tissue per aspiration and are more likely to result in diagnostic tissue, but the benefits of minimally-invasive aspiration diminish.

If a fine needle aspiration does not return diagnostic material, it may be repeated. Alternatively, if appropriate, a core biopsy may be attempted.

Maintaining patient comfort depends on multiple factors including: appropriate administration of local anesthesia, minimizing the number of samples, and obtaining enough material to prevent having to call the patient back. The last two are often in conflict with each other.

Advantages• Better precision • Increased chances of positive result• Out-patient procedure; less burden on patient and physician• Real time visualization of needle and guiding it to target lesion.• Helpful in documentation• Reach lesions situated in deeper planes

Pitfalls• Failure to recognize the lesion• Failure to direct the needle properly or visualize it• Failure to prepare the slides properly