Image-Guided Biopsy

Biopsy under image control is the sampling of tissue from a lesion, organ or lymph node using a needle placed under ultrasound, CT, fluoroscopy or MR control.

Fine needle aspiration (21 to 25 gauge) yields cells for cytology, and core biopsy (14 to 20 gauge, automated spring loaded or semi-automatic needles, coaxial systems) yields tissue cores for histology, immunohistochemistry and molecular tests.

Ultrasound is preferred for superficial organs, liver, kidney, thyroid, breast, lymph nodes, pleura and pelvis because it shows the needle in real time without radiation. CT is used for lung, mediastinum, bone, retroperitoneum, deep abdominal and pelvic lesions, using intermittent scanning or fluoroscopy mode.

Fluoroscopy is used for bone, spine and some chest lesions, and MR for lesions seen only on MR (prostate, breast, brain, musculoskeletal). Biopsy under endoscopic ultrasound reaches pancreas, nodes and gastric wall lesions. The planned path avoids vessels, bowel, lung, nerves and ducts.

Biopsy under image control replaced much surgical biopsy because it is faster, cheaper, and has fewer complications. Diagnostic yield is 85 to 98% for core biopsy of most solid organs (liver about 95%, lung 85 to 95%, bone 70 to 90%, kidney over 90%, lymph node over 90% with core biopsy), and major complications occur in under 1 to 3%.

Tissue diagnosis changes treatment: it defines malignancy, type, grade and receptor or mutation status, confirms infection and directs targeted therapy.

Indications.

• Focal lesions in the lung, mediastinum, pleura, liver, spleen, pancreas, kidney, adrenal, prostate, breast, thyroid, bone and soft tissue, retroperitoneum and pelvis, when a diagnosis would change management.
• Lymphadenopathy of unknown cause (core biopsy is preferred to fine needle aspiration for lymphoma).
• Diffuse parenchymal disease: liver (fibrosis, hepatitis, infiltration), kidney (glomerular disease, transplant dysfunction), and lung or pleura (when other tests are inconclusive).
• Staging of known cancer: confirmation of metastasis or a second primary.
• Suspected infection: tuberculosis, fungal infection, osteomyelitis, discitis, abscess (with culture).
• Molecular profiling for treatment selection (receptor status, mutations).
• Not when the result will not alter treatment.
• Not when the lesion is a classic benign finding (haemangioma, simple cyst, focal nodular hyperplasia with typical imaging).
• Not when the lesion is potentially a hydatid cyst (relative), or if the patient cannot cooperate.

Contraindications. Uncorrectable coagulopathy (international normalised ratio over 1.5 to 1.8, platelets under 50 000 in each microlitre, with thresholds set by the local rule and the organ).

• Anticoagulants and antiplatelet drugs that cannot be paused.
• No safe path to the lesion.
• Severe pulmonary hypertension or respiratory compromise (for lung biopsy).
• A patient who cannot lie still or consent.

Relative contraindications:

• Suspected vascular lesion (aneurysm, arteriovenous malformation, haemangioma) or hydatid cyst.
• A single functioning kidney (for renal biopsy).
• Uncontrolled hypertension.
• Skin infection at the site.
• Pregnancy (use ultrasound).
• Large ascites (liver biopsy by the transjugular route).

Preparation.

• Informed consent with the risks (bleeding, pneumothorax, infection, tumour seeding, non-diagnostic sample) and alternatives explained.
• Review of imaging, blood count, clotting, group and screen where bleeding risk is high, and medicines.
• Stop anticoagulants and antiplatelets as the local rule requires: usually 5 to 7 days for aspirin or clopidogrel in high risk sites, and warfarin until the international normalised ratio is under 1.5.
• Fasting for 4 to 6 hours for abdominal and deep procedures; blood pressure under control.
• Local anaesthetic, with sedation or general anaesthesia in children and in selected cases; analgesia and monitoring.
• Planning of the access route and position (prone for kidney and posterior lung, supine for liver, decubitus for lung with pleural access), and a pathologist or cytotechnologist to check adequacy where available.

Technique. After skin cleansing and local anaesthesia, a coaxial introducer needle is advanced to the edge of the lesion under imaging control, with the needle tip seen at all times in ultrasound, or with repeated CT slices. The biopsy needle is passed through the introducer to obtain 2 to 4 cores (more for molecular studies), or 3 to 5 aspirates for cytology.

Samples are placed in formalin for histology, saline or sterile containers for culture, and fresh for flow cytometry or special tests. A tract embolisation (gelatin sponge) may be used to reduce bleeding in lung and kidney. Post-procedure imaging (chest film or CT for lung, ultrasound for liver and kidney) checks for complications. Patients rest for 2 to 6 hours with observation.

Findings.

• Adequate tissue: cellular material representative of the lesion, with a diagnosis of benign or malignant, tumour type, grade, receptor status and molecular markers.
• Non-diagnostic or non-representative sample: normal tissue, necrosis, blood only, or crush artefact; repeat biopsy or another route is considered, and imaging pathology concordance is checked (a benign result that does not fit the imaging must be viewed with caution).
• Specific diagnoses: carcinoma, lymphoma, sarcoma, metastasis from a known or unknown primary, granuloma (tuberculosis, sarcoidosis), infection with organisms, fibrosis, cirrhosis, glomerular disease, and rejection in transplant organs.
• Imaging findings at the end: needle tip in the lesion, small haematoma or pneumothorax, and procedure related changes.

Critical findings needing immediate action. Large or expanding haematoma, haemorrhage with haemodynamic instability (resuscitation, embolisation or surgery), tension pneumothorax (needle decompression and chest drain), air embolism (left lateral decubitus, 100% oxygen, hyperbaric treatment), perforation of bowel or bile leak (antibiotics, surgery), sepsis after biopsy,

malignant diagnosis needing urgent oncology review, lymphoma diagnosis, and infection findings (positive culture) needing treatment.

Complications.

• Bleeding (the commonest major complication): liver 0.3 to 0.5%, kidney haematoma common but transfusion needed in 1 to 2%, lung haemorrhage and haemoptysis 5 to 10% minor.
• Pneumothorax: 15 to 40% of lung biopsies, chest drain in 5 to 15%; the risk is higher with emphysema, deep lesions and small lesions.
• Pain, vasovagal reaction, and infection and sepsis (rare, under 1%).
• Bile leak or peritonitis.
• Organ injury (bowel, bladder, pancreatitis after pancreatic biopsy).
• Tumour seeding along the tract (rare, about 0.01 to 0.1%).
• Arteriovenous fistula (after renal biopsy).
• Air embolism (rare) and death (about 1 in 1000 to 1 in 10 000).

Non-diagnostic rates are 5 to 15%.

Aftercare.

• Bed rest for 2 to 6 hours (liver and kidney: lying on the right side for liver, supine for kidney), with observation of pulse, blood pressure, pain and urine output every 15 to 30 minutes at first.
• Chest film at 1 to 4 hours after lung biopsy, and repeat if symptoms.
• Avoid heavy lifting, straining, and anticoagulants and antiplatelet drugs for the period the operator sets (usually 24 to 72 hours or more).
• Analgesia with paracetamol; avoid non-steroidal drugs for a few days.
• Return for increasing pain, fever, shortness of breath, blood in the urine, vomiting blood, dizziness, or swelling at the site.
• Pathology results in 2 to 7 days (longer for immunohistochemistry and molecular tests), reviewed at the multidisciplinary meeting with imaging.

Special groups.

• Children: general anaesthesia or sedation, ultrasound preferred, and coagulation checked; lesion biopsy in a specialist centre.
• Pregnancy: biopsy under ultrasound; avoid CT.
• Patients on anticoagulants: bridging and timing set with the prescribing team.
• Chronic liver disease: transjugular route for liver biopsy with ascites or coagulopathy.
• Immunosuppressed patients: aim for cultures and special stains for infection.
• Regions: tuberculosis, lymphoma, Kaposi sarcoma, hepatocellular carcinoma, and hydatid cyst are common targets. Biopsy under ultrasound with a basic scanner is widely available, but pathology capacity and immunohistochemistry may be limited, so samples may need transport to a referral laboratory.