Interventional Ultrasound “Fine-Needle Aspiration Biopsy (FNAB)”

Preparations and Technique

Setup (Fig.bellow): The supplies include sterile drapes and gloves

Prerequisites:
x Adequate coagulation: Quick PT i 70 %, platelets i 100 000/mm3. Factor analysis (e.g., factor XIII) may be indicated in patients with a hematologic systemic disease.
x Secure informed consent.
x Confirm a safe puncture route.

Materials for fine-needle aspiration biopsy:
1 Syringe, needle, razor, local anesthesia.
2 Syringe with citrate.
3 Angiomed core needles. Otto needles 0.8 mm, 0.95 mm, 1.2 mm, or
4 glass slides with a formalin-filled Eppendorf tube

Technique with a FNAB transducer

x To maintain asepsis, the transducer must be sterilized (e.g., by placing it in disinfectant solution), and it may be necessary to line the guide channel of the biopsy transducer with sterile film. An antiseptic spray can be used as the ultrasound coupling medium.
x Visualize the target lesion (Figs. 1a, 2a) in bellow

a,1 Fine-needle aspiration biopsy. a Rounded, hypoechoic intrasplenic mass (TU). and a2 Elliptical, hypoechoic mass (TU) in the region of the right adrenal gland. L = liver.

b The lesion is visualized, here using a linear transducer with a central biopsy channel. The needle path is marked on the screen. The insertion depth is measured (arrow), and the position of the tip echo at the target site (arrow) is checked. S = spleen

fig 2. b The mass is visualized, the needle path is marked, and the depth is measured (arrowhead). c The position of the tip echo at the target site (arrow) is checked

Preparation of the sample:
x Expel the material (mixed with citrate) onto a glass slide.
x Transfer larger tissue particles into a formalin-filled Eppendorf tube.
x Spread out and air-dry the cytologic sample.
x Liquid samples should undergo cytologic and bacteriologic analysis (Fig. bellow)

Therapeutic fine-needle aspiration and drainage. a Rounded, sharply circumscribed intrasplenic mass with a nonhomogeneous internal echo pattern. b Diagnostic fine-needle aspiration yielded abscess material. Arrow: needle tip echo. c The abscess material (140 mL) was therapeutically evacuated at the same sitting. S = spleen, A = abscess

Indications and Guidelines for Specific Organs
Liver:
x Indications: Investigation of diffuse and focal abnormalities
Note: With superficial lesions, make sure the lesion is biopsied through normal liver tissue.
Spleen
x Indications: Abscess, primary focal lesions
Note: The spleen is a very vascular organ, and strict criteria should be applied in patient selection.
Pancreas
x Indication: Carcinoma
Note: It is unnecessary to establish a preoperative histologic diagnosis for indeterminate pancreatic masses that are localized and operable.
x FNAB of a pancreatic mass is unnecessary if diagnostic imaging indicates a malignant tumor and operative treatment is planned.
Adrenal gland:
x Indication: Indeterminate mass lesion.
Caution: Before puncturing an adrenal mass, first exclude pheochromocytoma clinically and by laboratory tests.
Lymph nodes:
x Indications: Malignant lymphoma, metastasis, reactive lymphadenopathy.
x Limitations: FNAB is inadequate in most cases for the evaluation of a suspected malignant lymphoma; surgical lymphadenectomy is usually required.
Kidney

x Indications: Suspected tumor, parenchymal disease.
! Caution: If hypernephroma is suspected, a preoperative needle biopsy is not advised because of the risk of bleeding and inoculation metastasis.

Thyroid gland:
x Indications: Cold nodule, cyst
Note: Often there is no need for local anesthesia.

Accumulations of fluid:
x Indications: Pleural effusion, pericardial effusion, ascites, cyst, pseudocyst, hematoma, abscess.
* Note: Percutaneous aspiration may be diagnostic or therapeutic.
x In the therapeutic aspiration of a pleural effusion, no more than 1.5 L should be evacuated in one sitting. If the effusion is under negative pressure, aspirating even a small volume may cause a significant shift of the mediastinum (common with malignant effusions), and the procedure should therefore be terminated if
the patient manifests chest pressure or a dry cough.

Other indications: Lesions of the retroperitoneum, chest wall, subpleural lung, mediastinum, bone, gastrointestinal tract, soft tissues, etc.
Contraindications biopsy guiding with ultrasound:
Refusal of informed consent or lack of patient cooperation Severe coagulation disorder Noninvasive diagnostic alternatives Lack of therapeutic implications
! Caution: Be careful when dealing with very vascular superficial lesions.
Interpretation
General :

x Focal lesions ( i 2 cm in diameter) in parenchymal organs (e.g., liver, pancreas,retroperitoneum, adrenal gland) are diagnosed with approximately 90% sensitivity and 100% specificity.
x Complications (excessive pain, peritoneal irritation, bleeding, infection, inoculation metastasis, bile leak, pneumothorax, death) are extremely rare when the puncture route is carefully selected and contraindications are noted.

Specific risks:
x Liver: With superficial lesions, a hemangioma should be excluded with very high confidence because of the risk of bleeding.
x Pancreas: Confirm a safe puncture route because of the risk of bowel injury.
x Kidney: Apply rigorous patient selection criteria.
x Pleura: When draining an effusion, discontinue at once if the patient complains of chest pressure or tightness or develops a dry cough, because of the risk of mediastinal displacement
Fine-Needle Aspiration Biopsy (FNAB)
Technique biopsy guiding with ultrasound