Interventional Radiology: Diagnostic and Therapeutic Angiographic Procedures - Indications, Contraindications, Complications, and Reporting

Overview

This learning objective spans the breadth of diagnostic and therapeutic interventional radiology procedures. Competency requires understanding of indications, contraindications, procedural limitations, complications (early and late), post-procedure imaging appearances, and systematic reporting for each procedure. Notes are structured around the two major subdivisions: diagnostic and therapeutic.

Diagnostic Procedures

Transvenous (Transjugular) Liver Biopsy

Indications: Coagulopathy or thrombocytopaenia precluding percutaneous biopsy; ascites; suspected vascular liver disease (e.g. Budd-Chiari syndrome); combined HVPG measurement; morbid obesity; failed percutaneous approach.

Contraindications: Absence of suitable central venous access; cystic or vascular hepatic lesion in the target zone; uncooperative patient without adequate sedation.

Limitations: Smaller tissue cores than percutaneous biopsy; fragmentation artefact; sampling error; cannot target focal lesions precisely.

Complications: - Early: Capsular perforation with intraperitoneal haemorrhage, hepatic arteriovenous fistula, transient right bundle branch block, neck haematoma at access site - Late: Haemobilia, pseudoaneurysm (rare)

Reporting: Document sample adequacy, number of cores, portal tracts identified, and any immediate haemodynamic or imaging change.

$$\text{HVPG} = \text{WHVP} - \text{FHVP}$$

HVPG $\geq 10\,\text{mmHg}$ defines clinically significant portal hypertension; $\geq 12\,\text{mmHg}$ correlates with variceal haemorrhage risk.

Diagnostic Angiography

Aortoiliac Angiography

Indications: Assessment of PAD, aortoiliac occlusive disease (Leriche syndrome), pre-procedural planning for endovascular repair, post-operative surveillance.

Contraindications: Severe contrast allergy without adequate pre-medication; acute renal impairment (use CO₂ or gadolinium alternatives); uncorrectable coagulopathy.

Limitations: Invasive; two-dimensional projection imaging; does not assess vessel wall pathology or haemodynamic significance without pressure measurements.

Normal appearances: Smooth aortic contour, symmetric iliac filling, well-defined vessel calibre; infrarenal aorta approximately $18$-$25\,\text{mm}$ at the level of the renal arteries in adults.

Complications: Access site haematoma, pseudoaneurysm, arteriovenous fistula, dissection, distal embolisation, contrast-induced nephropathy, radiation injury.

Coeliac, Hepatic, Splenic, and Mesenteric Studies

Indications: GI haemorrhage localisation and treatment; pre-operative hepatic arterial mapping; tumour vascularity assessment; acute or chronic mesenteric ischaemia; visceral aneurysm evaluation; trauma.

Normal anatomy:

Pathological findings: Active extravasation, pseudoaneurysm, arteriovenous fistula, early draining vein (angiodysplasia/AVM), vessel cut-off, encasement, neovascularity (tumour).

• Splenic artery is the most commonly affected visceral vessel by true aneurysm (60% of visceral aneurysms); overall visceral aneurysm prevalence is 0.1-0.2% of all arterial aneurysms
• Angiodysplasia: tangle of vessels with an early draining vein on selective angiography (most commonly right colon/ileocolic territory)
• Angiography detects GI haemorrhage at rates $\geq 0.5\,\text{mL/min}$; MDCTA detects lower rates and typically precedes angiography in the diagnostic algorithm
• Catheter angiography for mesenteric ischaemia is reserved for endovascular therapy or high clinical suspicion with equivocal cross-sectional imaging (particularly for non-occlusive mesenteric ischaemia)

Typical angiographic findings in trauma: Active extravasation, pseudoaneurysm, arteriovenous fistula, truncated vessels, or vessel irregularities.

Renal Angiography

Indications: Renal artery stenosis (fibromuscular dysplasia, atherosclerosis), renal trauma, tumour embolisation planning, transplant vascular assessment (stenosis, pseudoaneurysm, AVF).

Pathological findings: Beaded appearance of FMD (medial type); ostial calcified eccentric plaque in atherosclerosis; pseudoaneurysm; AVF; active extravasation post-trauma.

Transplant-specific vascular complications (occur in $< 10\%$): renal artery stenosis (treatment: transluminal balloon dilation ± stent), arterial/venous thrombosis (mechanical thrombectomy or thrombolysis in select cases), pseudoaneurysm and AVF (superselective embolisation - first-line).

Lumbar Angiography

Indications: Type 2 endoleak surveillance and treatment following EVAR (lumbar artery contribution); spinal AVM; pre-surgical vascular mapping.

Venography

Indications: DVT assessment when ultrasound is inconclusive; pre-procedural venous mapping; venous occlusion evaluation for SVC/IVC stenting; varicocele assessment (left gonadal vein reflux into left renal vein); TIPS planning; Budd-Chiari syndrome evaluation.

Contraindications: Contrast allergy (use CO₂ or gadolinium); severely impaired access veins.

Limitations: Largely replaced by duplex ultrasound and CT/MR venography in many scenarios; invasive.

Complications: Thrombophlebitis, contrast extravasation, post-venography thrombosis, allergic reaction.

Reporting: Document filling defects, collateral formation, reflux, stenosis, and calibre changes.

Nephrostogram

Indications: Assessment of pelvicalyceal anatomy, ureteric patency, and stricture site/length prior to antegrade stenting or balloon dilation; performed via existing nephrostomy catheter.

Stricture causes amenable to antegrade balloon dilation: Iatrogenic/traumatic injury, retroperitoneal fibrosis, tuberculosis, post-radiation, uretero-ileal anastomosis stricture.

Limitations: Requires existing nephrostomy access; limited distal ureteric evaluation without oblique projections; risk of sepsis if contrast injected under pressure into an obstructed system.

Complications: Pyelovenous/pyelolymphatic backflow (high-pressure injection), sepsis, contrast extravasation, ureteric rupture during dilation (managed by nephrostomy drainage; procedure reattempted after several weeks).

Reporting: Document pelvicalyceal morphology, stricture location and length, degree of obstruction, contrast transit to bladder, and any fistulous communications or extravasation. Stricture balloon dilation endpoint: disappearance of balloon waist. Ureteric stent typically removed at 4 weeks post-dilation.

Cholangiogram

Indications: Percutaneous transhepatic cholangiography (PTC)/PTBD for biliary obstruction characterisation when ERCP has failed or anatomy is altered (e.g. Roux-en-Y hepaticojejunostomy, post-liver transplant bile leak); tube cholangiogram via existing T-tube or external drain; operative cholangiogram.

Contraindications to PTBD/PTC: Uncorrectable coagulopathy; complete absence of biliary dilatation (relative); large intervening ascites; multiple hepatic metastases limiting safe access.

Approach considerations: External drainage preferred in septic patients to minimise biliary tree manipulation. Self-expanding metallic stents (SEMS) reserved for malignant obstruction with limited life expectancy (stents eventually occlude). Benign strictures managed with balloon dilation and long-term internal-external drains; permanent stenting generally avoided. Bile leak/injury: ERCP with stent is first-line; PTBD used when endoscopic access fails or anatomy is altered (biliary tree may be non-dilated, making cannulation challenging).

Limitations: Risk of introducing infection into an obstructed system; haemobilia risk; non-diagnostic if biliary access cannot be achieved.

Complications: Biliary sepsis/cholangitis, haemobilia, bile leak/biloma, pneumothorax (right-sided approach), vascular injury, pancreatitis (uncommon).

Reporting: Document stricture site and length, degree of proximal dilatation, filling defects (stones, tumour), whether wire crosses the obstruction, and any fistulous tracts.

Therapeutic Procedures

Drainage Catheter Placement

Trans-rectal / Trans-vaginal Abscess Drainage

Indications: Deep pelvic collections (peri-rectal, tubo-ovarian abscess, post-operative pelvic collections) not accessible by transabdominal route. Ultrasound vs CT guidance: both used; transgluteal approach is an additional option for collections lateral to the rectum.

Contraindications: Uncooperative patient; intervening viscera or major vessels; uncorrectable coagulopathy (relative).

Limitations: Access limited by pelvic anatomy; smaller catheter sizes than transabdominal approach; post-procedure discomfort.

Complications: Haemorrhage; inadvertent bowel/bladder/vascular injury; septicaemia; fistula formation; catheter displacement.

Post-procedure imaging: Follow-up CT or ultrasound to confirm cavity resolution and catheter position; sinogram may document communication with other structures.

Cholecystostomy

Indications: Acute cholecystitis (calculous or acalculous) in patients unfit for surgery; bridge to elective cholecystectomy; biliary decompression.

Contraindications: Uncorrectable coagulopathy; no safe imaging window; uncollapsed gallbladder inaccessible by any route.

Approaches: Transhepatic (preferred - reduces bile peritonitis risk) or transperitoneal. US or CT guidance used; catheter placement techniques vary (Seldinger vs trocar).

Complications: Bile leak, haemorrhage, hepatic injury, tube displacement, peritonitis, vagal reaction.

Post-procedure imaging: Cholangiogram via tube confirms patency and anatomy. Resolution of pericholecystic fluid and wall thickening expected over 1-2 weeks on follow-up imaging.

Balloon Angioplasty and Stenting - Aortoiliac

Indications: Symptomatic PAD with iliac stenosis/occlusion; Leriche syndrome; renovascular hypertension; mesenteric ischaemia from stenosis. TASC II classification guides decision between endovascular and surgical approach.

Contraindications: Fresh thrombus (may require thrombolysis first); heavily calcified occlusion not wire-crossable; inability to tolerate antiplatelet therapy; access vessel too small for delivery system.

Stent types: - Balloon-expandable: Deployed by balloon inflation; preferred for ostial and calcified lesions; precise deployment - Self-expanding: Radial force deployment; preferred for non-ostial, longer, and tortuous lesions; used for most iliac and mesenteric interventions

Drug-eluting balloons (DEB): Reduce neointimal hyperplasia; useful for vessels too small for stenting; leave no permanent metal; risk of downstream drug microparticle migration.

Limitations: - Restenosis from neointimal hyperplasia (up to 50% at 12 months in infrainguinal territory) - Better patency in proximal large vessels (common iliac artery) than distal small vessels - Stent fracture in high-flex zones - Atherectomy may be used adjunctively for calcified plaques

Complications:

Reporting post-intervention: Residual stenosis target $< 30\%$; pressure gradient: significant if $> 10\,\text{mmHg}$ at rest or $> 15\,\text{mmHg}$ post-vasodilator; document distal runoff.

Endovascular Aneurysm Repair (EVAR)

Indications: - Infrarenal AAA $\geq 5.5\,\text{cm}$ (men), $\geq 5.0\,\text{cm}$ (women); symptomatic or rapidly expanding AAA ($> 1\,\text{cm/year}$) - Thoracic aortic aneurysm $\geq 6\,\text{cm}$ (TEVAR); aortic trauma; penetrating aortic ulcer; complicated type B aortic dissection

Thoraco-abdominal aneurysm (Crawford classification):

Hybrid repair (surgical visceral bypass + stent-graft exclusion) carries peri-procedural mortality of approximately 15-20%. Fenestrated (FEVAR) and branched endografts (with technical success ~98.9%) are preferred for juxtarenal and thoraco-abdominal aneurysms where branch perfusion must be preserved.

Anatomical prerequisites (standard infrarenal EVAR): - Infrarenal neck length $\geq 15\,\text{mm}$ - Neck diameter $\leq 32\,\text{mm}$ - Neck angulation $< 60°$ - Iliac access vessels $\geq 7$-$8\,\text{mm}$ (delivery systems: 14-25 Fr / ~4-9 mm) - Absence of heavy thrombus/calcification or severe angulation in the neck

Adverse neck anatomy: Short neck, barrel neck, conical neck, angulation $\geq 60°$, significant mural thrombus/ulceration - each increases risk of type 1 endoleak and migration.

Adjunctive access techniques: Angioplasty/stenting of access vessels; "Pave and Crack" (deliberate controlled over-dilation); surgical conduit in severe iliac disease.

Deployment considerations: "Windsock effect" (systolic pressure forcing device distally during deployment) - managed by overdrive cardiac pacing or pharmacological blood pressure reduction, particularly critical for short/angulated proximal necks in TEVAR. Once fully released, device cannot be repositioned without open surgery.

Infrastructure requirements: Hybrid theatre with fixed C-arm image intensification; fusion imaging capability; CBCT for complex procedures; CO₂/gadolinium angiography for patients with contrast allergy or renal impairment; 24/7 vascular surgical, anaesthetic and radiological support; ICU/HDU availability.

Endoleak Classification and Management:

Graft infection: CT signs include air within aneurysm sac beyond immediate post-procedure period and/or periaortic inflammatory stranding. Aorto-enteric fistula is a rare but potentially fatal complication; may cause or result from endograft infection.

Post-procedure imaging protocol: CTA at 1 month, 12 months, then annually. Assess: sac diameter, endoleak type, device position, iliac limb patency, renal function. Duplex ultrasound (with contrast enhancement) is a radiation-sparing surveillance alternative in stable patients.

Embolisation

Tumour Embolisation - Benign and Malignant

Indications:

HCC locoregional therapy options: - Curative: PEI, RFA, MWA, cryoablation, irreversible electroporation (IRE) - Palliative: Bland TAE, cTACE, DEB-TACE, SIRT (Y-90 microspheres) - BCLC staging system guides selection; tumour stage, liver function (Child-Pugh), and performance status are key variables

Contraindications to TACE: Main portal vein thrombosis (relative); Child-Pugh C hepatic decompensation; bilioenteric anastomosis without prophylactic antibiotics; uncorrectable coagulopathy.

Embolic agents:

Complications: Post-embolisation syndrome (fever, pain, nausea - expected after large-volume embolisation; distinguish from sepsis by absence of positive blood cultures); non-target embolisation; abscess; biloma; hepatic infarction; hepatic artery pseudoaneurysm (1%, rare); biliary fistula.

Post-procedure imaging response assessment (TACE/SIRT): mRECIST criteria - based on enhancement of viable (arterially enhancing) tumour, not total tumour size. Lipiodol retention on CT correlates with treatment response (cTACE). MRI with DWI and hepatobiliary agent-enhanced arterial phase is preferred for residual viable tumour assessment.

Visceral Aneurysm Embolisation

True mesenteric aneurysms are rare (0.1-0.2% of all arterial aneurysms); splenic artery is the most commonly affected (60%). Most found incidentally on cross-sectional imaging.

General indications for intervention: Aneurysm $> 2.0$-$2.5\,\text{cm}$; symptomatic; women of childbearing age; patients awaiting liver transplant; multiple hepatic aneurysms; interval growth $> 0.5\,\text{cm/year}$.

Treatment options: Coil embolisation, exclusion with covered stent, thrombin injection, liquid embolic agents - choice depends on location and individual anatomy.

Haemorrhagic Lesions and Trauma

Indications: Solid organ injury (liver, spleen, kidney) with active extravasation or pseudoaneurysm on CT; pelvic fracture haemorrhage; post-procedural haemorrhage (e.g. post-biopsy, post-biliary); mesenteric haemorrhage; post-partum haemorrhage; GI haemorrhage (upper: proximal to duodenojejunal flexure - commonly peptic ulcer, pancreatitis, post-procedural; lower: commonly angiodysplasia, diverticular disease, neoplasm).

Hepatic trauma specific points: - Re-bleeding/secondary haemorrhage: 1.7-5.9%; mortality up to 18%; majority (69%) managed non-operatively - Hepatic artery pseudoaneurysm: ~1%; asymptomatic PSA should be treated promptly (high rupture risk); haemobilia (melena/haematemesis) = ruptured intrahepatic PSA until proven otherwise → angioembolisation is treatment of choice - Biliary complications (biloma, biliary fistula, bilhemia, bile peritonitis): 2.8-30%; most traumatic bilomas resolve spontaneously; enlarging/symptomatic/infected bilomas → percutaneous drainage ± endobiliary stent; bile peritonitis → laparoscopic irrigation/drainage + endoscopic stent - Embolic agents in coagulopathy: NBCA or Onyx preferred over particulate agents

Limitations: Superselective technique required to minimise non-target infarction; technical failure in tortuous or vasospastic vessels.

Complications: Non-target embolisation; hepatic/splenic/renal abscess; organ infarction; biloma; post-embolisation pseudoaneurysm; access complications.

Mesenteric Intervention - Summary

Acute mesenteric ischaemia causes: Thromboembolism to SMA (most common), SMA thrombosis on atherosclerosis, SMA venous thrombosis, non-occlusive mesenteric ischaemia (NOMI, $< 20\%$ of cases), vasculitis, dissection, iatrogenic.

Catheter angiography role: Reserved for endovascular therapy or high clinical suspicion with equivocal imaging - especially NOMI.