SC05 - Interventional radiology

Question 1

Interventional radiology

• Definition
• Function
• Advantages

Answer 1

Definition: range of techniques which rely on the use radiological image guidance (X-ray fluoroscopy, ultrasound, computed tomography [CT] or magnetic resonance imaging [MRI]) to precisely target therapy

Function:
- Diagnostic: Histological sampling, treatment planning
- Therapeutic: Vascular intervention, Interventional oncology, non-vascular intervention

Advantages:
* Minimally invasive procedures
* Provide alternative to surgery in suitable patients
* Hospital admission often not required
* Quick recover, less pain and complications
* Usually use local anaesthesia
* Generally safe & effective

Question 2

Interventional radiology

Contraindications
Complications

Answer 2

Contraindications:
* Uncontrolled bleeding diathesis
* Uncooperative patient
* Patient refusal
* Contraindications specific to intervention

Complications:
- Vascular damage: bleeding, AV fistula, pseudoaneurysm
- Infection
- Organ damage
- Needle tract tumour seeding
- Mucosal breach e.g. pneumothorax

Question 3

Interventional radiology

Sampling techniques and differences

Answer 3

1. FNA/ Cytology

• US guided for deep/diffuse lesions
• No histological information/ spatial arrangement of cells
• Organs biopsied: thyroid, parotid, lymph nodes, breast, gastrointestinal tract, mediastinum, (liver, lung, bone)

2. Targeted biopsy
   - USG/ CT/ MR guided for precise placement
   - Provides histological information
   - Organs biopsied: kidney, liver, breast and lymph nodes

Question 4

Interventional radiology

Modalities of vascular intervention

Answer 4

Arterial:
* Balloon angioplasty and stenting: percutaneous access for recannalisation of arteries, revascularization of limbs or end organs, AAA repair
* Thrombolysis: e.g. catheter-directed thrombolysis for stroke
* Haemorrhage control and Embolization of acute visceral bleeding

Venous
* Central venous access
* IVC filter: for recurrent PVT/ PE despite anticoagulation or high risk of DVT/PE with absolute contraindication for anticoagulants
* Fistula intervention

Question 5

Trans-arterial chemo-embolization

• MoA
• Complications
• Contraindications

Answer 5

MoA:
- Cytotoxic agent mixed into an emulsion with lipiodol selectively uptaken by HCC cells to be released slowly
- Gelfoam particles block the washout by the arterial flow and “locks” in the cytotoxic agent within the tumour cells

Complications:
- Post-embolization syndrome (common): nausea, vomiting, abdominal pain, loss of appetite, fever
- Others (Uncommon): Cholecystitis, upper GI bleeding, gastric/duodenal necrosis, acute pancreatitis, hepatic abscess, rupture

Contraindication:
- Main portal vein tumour thrombosis: further embolization of hepatic artery may cause hepatic ischemia
- Extra-hepatic metastasis
- Poor liver function (serum bilirubin >50 µ mol/L)

Question 6

Non-vascular interventions

• Examples
• Conplications

Answer 6

Drainage: under Fluoroscopy, US, CT and MRI guidance
- Abscess drainage
- Percutaneous trans-hepatic biliary drainage (PTBD): treatment of obstructive jaundice, biliary sepsis, post-operative bile leaks, MBO, anastomotic strictures after transplant/ anastomosis
- Percutaneous nephrostomy (PCN)
- Gastro-duodenal stenting for GOO
- Palliative drainage

Complications:
- Sepsis
- Organ damage
- Hemorrhage
- Death secondary to above complications

Question 7

Interventional oncology

• Modalities of treatment

Answer 7

Modalities:
* radiofrequency ablation (RFA)
* microwave coagulation
* interstitial laser therapy
* cryosurgery
* high intensity focused ultrasound (HIFU)

Question 8

RFA for HCC

• MoA
• Advantage

Answer 8

MoA:
- Minimal invasive procedure using 14-20 gauge RF electrodes
- US/CT guidance
- Tip of RF probe placed at center of target tissue
- Tissue destruction by resistive heating

Advantage:
- Better local tumour control for <2cm HCC treated by RFA compared with PEI
- Effective in local tumor control for HCC & liver metastasis
- relative ease of use & low cost

Question 9

HIFU for HCC

• MoA
• Advantage
• Disadvantage

Answer 9

MoA:
- thermal coagulative necrosis
- acoustic cavitation
- damage to tumour vasculature
- US or MRI guidance

Advantage:
- avoid risk & complication of needle or electrode placement
- ability to treat large tumour >5cm

Disadvantage:
- long treatment time
- GA risk