GC014 How Can Interventional Radiology Help Patient Management
Interventional radiology uses image-guided, minimally invasive procedures—such as angiography, embolization, drainage, biopsy, and stenting—to diagnose and treat a wide range of conditions, thereby reducing surgical morbidity and improving patient management.
How Can Interventional Radiology Help Patient Management
This GC lecture by Dr. Vince Lau (Honorary Clinical Associate Professor, HKU; Consultant Radiologist, QMH) provides a comprehensive overview of Interventional Radiology (IR) — a specialty that sits at the intersection of diagnostic imaging and minimally invasive therapy. The lecture is structured around a "week in the IR suite" at QMH, walking through the major clinical domains day by day: Vascular IR → Interventional Oncology → Musculoskeletal IR → Neuro IR → Aortic Intervention → Emergency/Urgent Cases, and finally closing with a summary of the roles, advantages, and scope of IR.
Why this matters for exams: The lecture tests your ability to (1) understand what IR procedures exist and when they are indicated/contraindicated, (2) compare IR alternatives against surgical approaches, (3) recognize complications, and (4) apply clinical reasoning to urgent case scenarios. Past papers commonly ask about TACE for HCC, percutaneous drainage, embolization for haemorrhage control, and nephrostomy — all covered here.
Learning Objectives (inferred from slide content and the IR 2025 supplementary deck) [1][2]:
- Define interventional radiology and understand its principles
- Know the scope: vascular and non-vascular procedures
- Understand indications, contraindications, and complications of common IR procedures
- Appreciate the perioperative evaluation of IR patients
- Recognize when IR provides an alternative to open surgery
How to use these notes
The cases, device names, complication percentages, and BCLC/HKLC diagrams in this 2021 lecture are valuable teaching material, but they are not a current treatment protocol. The sections labelled Current-practice correction (reviewed August 2026) distinguish the slide-era message from guidance that has since changed.
Core Concept: What Is Interventional Radiology?
"A specialty in medicine providing minimally invasive, image-guided therapy for conditions in virtually all body systems." [1]
Key Analogy from Lecture – High Yield
Laparoscopy = keyhole surgery; IR = pinhole surgery (微創針孔手術 / 介入治療) [1]. This captures the essential advantage: even less invasive than laparoscopic surgery, using needles and catheters rather than ports and trocars.
First-principles explanation: IR leverages real-time imaging (fluoroscopy, ultrasound, CT, MRI) to guide needles, wires, catheters, and devices through the skin or blood vessels to the target. Because there is no large incision, patients experience less pain, shorter hospital stays, and faster recovery. The trade-off is that some procedures have higher reintervention rates compared to definitive surgery.
- Vascular access is coaxial: needle → guidewire → sheath → diagnostic catheter → microcatheter. Each smaller layer permits more selective navigation while the outer access remains stable.
- Therapy is delivered at the catheter tip: particles, coils, liquid embolic or sclerosant are chosen according to whether distal capillary-bed occlusion, focal vessel closure, or malformation treatment is required.
- Non-vascular access uses the same principle: an image-guided needle establishes a safe path, then a wire allows exchange for a drainage catheter or treatment probe.
- The biplane angiography suite acquires two projections during one contrast injection; cone-beam CT/DynaCT can add cross-sectional and 3D information without moving the patient out of the room.
| Modality | Strengths | Limitations |
|---|---|---|
| Ultrasound | Real-time, no radiation, portable, flexible | Operator-dependent, obscured by bowel gas/bone |
| Fluoroscopy | Real-time, good for vascular work | Radiation exposure, 2D only (unless DynaCT) |
| CT | Precise localization, excellent anatomy | Radiation, intermittent imaging (not truly real-time) |
| MRI | Superior soft-tissue contrast | Slow, more contraindications, limited availability |
| Role | Examples |
|---|---|
| Diagnostic | Histological sampling (biopsy), treatment planning |
| Therapeutic – Vascular | Angioplasty/stenting, thrombolysis, embolization |
| Therapeutic – Non-vascular | Abscess drainage, nephrostomy, biliary drainage |
| Interventional Oncology | Ablation (RFA, MWA, cryoablation), TACE |
Minimally invasive procedures; provide alternative to surgery in suitable patients; hospital admission often not required; quick recovery, less pain and complications; generally safe and effective. [1]
- Confirm the indication, target and desired endpoint with the clinical team; IR is a clinical specialty, not simply a procedural service.
- Review bleeding and thrombotic risks, anticoagulants/antiplatelets, renal function when iodinated contrast is planned, allergies, infection risk, pregnancy status where relevant, and anaesthetic needs.
- A lesion without a safe percutaneous or endovascular path may need repositioning, fusion imaging, hydro-/pneumodissection, another modality, or a different treatment.
- Do not apply a universal “INR < 1.5 and platelets > 50” rule to every procedure. SIR guidance stratifies procedures by bleeding risk and recommends individualized management, especially in chronic liver disease [19].
- Local anaesthesia is common, but sedation or general anaesthesia may be required; inability to cooperate is an anaesthetic/planning issue, not a blanket contraindication.
Vascular, Oncology, Gastrointestinal, Genitourinary, Neurointervention, Head and Neck, Musculoskeletal [1]
Monday – Vascular IR
PAE is a minimally invasive treatment that helps improve lower urinary tract symptoms (LUTS) caused by BPH. [1]
Do not skip the LUTS differential. The slide's wheel is a deliberate warning: nocturnal polyuria, detrusor overactivity or underactivity, neurogenic dysfunction, infection/prostatitis, urethral stricture, distal ureteric stone, foreign body and bladder malignancy can mimic “BPH symptoms.” PAE only treats symptoms attributable to benign prostatic obstruction.
Why it works [1]: bilateral superselective particle embolization reduces prostatic arterial flow, producing controlled ischaemia/infarction and later gland shrinkage. MRI may show non-enhancing prostatic infarcts; the slide examples also show reduced intravesical prostatic protrusion. A small shear-wave elastography study suggested reduced stiffness after PAE, but that pilot observation is mechanistic rather than a patient-selection test.
What the angiograms mean:
- Pelvic CTA maps iliac tortuosity, calcification, likely artery origins and collaterals.
- The prostatic artery has variable origins (often from inferior vesical/internal pudendal/obturator-related trunks) and may share bladder, rectal or penile supply.
- Selective DSA and, when needed, cone-beam CT confirm that the catheter perfuses prostate rather than a non-target organ.
- Particles are injected slowly to a near-stasis endpoint while avoiding reflux; bilateral treatment is attempted when safely possible.
Current-practice correction (reviewed August 2026)
NICE considers the safety and efficacy evidence adequate for routine governance, but selection should be joint between a urologist and interventional radiologist [11]. The lecture's fixed “prostate > 35 g” threshold is not universal. Assess symptom burden, objective obstruction/retention, prostate anatomy, prior medical therapy, patient preference and suitability for alternative procedures. Exclude or appropriately evaluate infection and suspected malignancy before treating presumed benign disease.
The slide-era claims of “no” erectile dysfunction, incontinence or retrograde ejaculation, guaranteed next-day discharge, and the quoted TURP mortality/infertility figures must not be used for counselling. PAE often preserves ejaculation better than resective surgery, but no treatment has zero risk; symptom improvement can be less marked or less durable than after TURP and retreatment may be required.
Practical work-up:
- Urologic assessment: history/IPSS and bother, urinalysis ± culture, renal function, PVR/flow assessment as appropriate, medication history and evaluation for retention or alternative causes.
- PSA and further cancer evaluation are interpreted clinically; PSA alone does not “exclude malignancy.”
- CTA/MRA or intraprocedural cone-beam CT may be used for arterial mapping depending on local workflow.
- CBC, coagulation and renal function are tailored to procedural and contrast risk.
Risks to consent: access-site bleeding/haematoma or pseudoaneurysm, contrast reaction or kidney injury, pelvic pain/post-embolization symptoms, transient dysuria/haematuria/haematospermia, UTI, acute urinary retention, treatment failure/recurrence, and rare non-target bladder, rectal or penile ischaemia. The lecture's percentage ranges are historical series, not universal patient-specific rates.
UFE is a procedure to shrink uterine fibroids. [1]
Read the anatomy before choosing treatment. The lecture's diagrams distinguish submucosal/intracavitary, intramural and subserosal fibroids. MRI demonstrates number, size, location, viability/enhancement and alternative pathology; these features help decide whether bleeding or bulk symptoms plausibly arise from the fibroids and whether UAE, myomectomy, hysterectomy or another treatment is most suitable.
What the angiographic sequence shows [1]:
- Selective angiography is performed on both uterine arteries, because supply to a fibroid uterus is usually bilateral and may be asymmetric.
- The tumour blush outlines the hypervascular peri-fibroid plexus.
- PVA particles (lecture examples: 355–500 or 500–700 µm) or tris-acryl gelatin microspheres (500–900 µm) are injected until marked flow reduction/near stasis.
- The post-embolization angiogram shows loss of fibroid blush while major uterine arterial flow is preserved; subsequent contrast MRI should show non-enhancement and later volume reduction.
Benefits and trade-offs: Compared with surgery, UAE usually offers shorter admission and recovery and less transfusion, but repeat intervention is more common. The slide's older 15–32% two-year surgical reintervention figure and selected long-term series below describe lecture-era cohorts, not a universal current estimate.
Long-term symptom relief data (selected trials) [1]:
| Trial | Symptom Relief | Reintervention Rate |
|---|---|---|
| Spies JB et al., Obstet Gynecol 2005 | 87% at 1 year; 73% at 5 years | 20% |
| Lohle PN et al., JVIR 2008 | 72% at 54 months | 28% |
| Scheurig-Muenkler C et al., JVIR 2013 | 82% at 5.7 years | 15% |
Current-practice correction (reviewed August 2026)
NICE states that UAE provides substantial symptom relief in many patients, but recurrence/reintervention can occur and effects on fertility and pregnancy remain uncertain; patient selection should involve a gynaecologist and interventional radiologist [12]. Viable pregnancy, active pelvic infection and suspected uterine/adnexal malignancy are exclusions. Future pregnancy requires individualized counselling rather than the blanket statement “UAE is contraindicated if fertility is desired.” A pedunculated subserosal fibroid is not automatically an absolute contraindication: stalk morphology, infarction/expulsion risk and alternative treatments are assessed case by case.
Clinical assessment before UFE [1]:
- Chief complaint: bleeding vs. bulk
- Menstrual history: duration, frequency, heavy days, clots/"gushes", pad/tampon frequency
- Intermenstrual bleeding → rule out polyps, hyperplasia, cancer
- Pelvic symptoms: pressure/"bloating", pelvic pain, leg/back pain, urinary frequency/nocturia/obstruction, dyspareunia, constipation
- Reproductive history: infertility, miscarriages, desire for future fertility
Workup [1]:
- US and MRI pelvis — critical questions:
- Does the patient actually have fibroids?
- Where is/are the fibroid(s)? Location consistent with symptoms?
- Intracavitary? Size?
- Are the fibroids viable?
- How large is the uterus?
- Vascular anatomy?
- Other pathologies?
- CBP, LFT, RFT, clotting profile
Procedure [1]:
- Femoral or radial arterial access; analgesia/sedation and admission pathway vary by patient and centre
- Bilateral selective uterine artery embolization to an angiographic endpoint
- Plan proactively for post-embolization pain, nausea and fever; distinguish expected post-embolization syndrome from infection or other complication
Embolic agents [1]:
- PVA (polyvinyl alcohol) particles: 355–500 µm, 500–700 µm
- Embosphere (tris-acryl gelatin microspheres): 500–900 µm
- Occlude at the peri-fibroid plexus level → selective ischaemia of fibroids while sparing normal myometrium
Risks to consent: access-site complication, contrast reaction/kidney injury, post-embolization syndrome, infection/endometritis, fibroid expulsion, treatment failure or later reintervention, ovarian dysfunction/amenorrhoea and rare uterine injury or emergency surgery. Amenorrhoea/ovarian insufficiency risk increases with age, but the slide percentages are historical cohort estimates rather than fixed individual risks.
Tuesday – Interventional Oncology
HCC is usually arterialized relative to background liver, enabling selective hepatic-arterial treatment. [1]
Why TACE works (first principles) [1]:
- Normal liver parenchyma receives ~75% of its blood supply from the portal vein and ~25% from the hepatic artery
- Most HCCs derive predominantly arterial supply, creating a therapeutic window for selective arterial treatment while portal flow supports non-tumour liver
- Conventional TACE delivers an iodized-oil/chemotherapy emulsion followed by embolization; dense lipiodol retention marks treated tissue but is not, by itself, proof of complete response
- Cytotoxic agent mixed into an emulsion with lipiodol is carried to tumour cells in high concentration and released slowly
- After delivering the chemotherapy-lipiodol emulsion, the feeding artery is embolized → dual effect of targeted chemotherapy + ischaemia
What the imaging sequence shows [1]: cross-sectional imaging first localizes the tumour. DSA depicts tumour blush, while cone-beam CT and 3D hepatic arterial maps help identify small feeders and reduce non-target treatment. The microcatheter is advanced selectively before embolization. Post-treatment CT may show lipiodol deposition; response is assessed on follow-up multiphasic CT/MRI by residual viable enhancement, not oil density alone.
Complications of TACE [1]:
| Common | Uncommon |
|---|---|
| Post-embolization syndrome: nausea, vomiting, abdominal pain, loss of appetite, fever | Cholecystitis, upper GI bleeding, gastric/duodenal necrosis, acute pancreatitis, hepatic abscess, rupture |
Current-practice correction (reviewed August 2026)
The slide teaches three simple exclusions—main portal-vein tumour thrombus, extrahepatic spread and bilirubin > 50 µmol/L—but these are not universal absolute contraindications. Contemporary HCC treatment is multidisciplinary and depends on tumour burden/distribution, portal flow, performance status, liver reserve, transplant strategy and available systemic or radiation options. Main portal-vein invasion and poor reserve substantially increase harm from embolization and often favour another therapy, yet selective TACE can be considered in carefully chosen patients with portal-vein thrombosis and preserved collateral flow [13][14]. Extrahepatic disease does not make liver-directed therapy intrinsically impossible, although it changes the overall treatment goal. A single bilirubin cutoff must not replace assessment of decompensation and hepatic reserve.
HCC Staging Systems
The lecture reproduces two historical algorithms [1]:
- Barcelona Clinic Liver Cancer (BCLC) Staging (2008)
- Hong Kong Liver Cancer (HKLC) Staging (2014) — a local system that allocated some patients to more aggressive treatment
They remain useful for understanding stage variables, but the treatment boxes—especially “sorafenib” as the sole advanced-stage option—must not be used as a 2026 protocol. The BCLC strategy has been updated and explicitly allows individualized clinical decision-making [13].
| Stage | Criteria | Treatment |
|---|---|---|
| 0 — Very early | Single tumour < 2 cm, PS 0, Child-Pugh A | Resection (if normal portal pressure) or RFA |
| A — Early | Single or ≤ 3 nodules ≤ 3 cm, PS 0, Child-Pugh A–B | Resection / Liver transplantation / RFA (curative) |
| B — Intermediate | Multinodular, PS 0, Child-Pugh A–B | TACE (palliative) |
| C — Advanced | Portal invasion, N1/M1, PS 1–2, Child-Pugh A–B | Sorafenib (palliative) |
| D — Terminal | PS > 2 or Child-Pugh C | Symptomatic/best supportive care |
| Tumour Status | Size | No. of Nodules | Intrahepatic Venous Invasion |
|---|---|---|---|
| Early | ≤ 5 cm | ≤ 3 | No |
| Intermediate | ≤ 5 cm & ≤ 3 nodules with venous invasion; OR ≤ 5 cm & > 3 nodules without invasion; OR > 5 cm & ≤ 3 nodules without invasion | — | — |
| Locally advanced | > 5 cm & > 3 nodules (any invasion); OR diffuse (any) | — | — |
HKLC treatment flow [1]:
- ECOG 0–1, Child A/B, no EVM → Early tumour: Resection / LT / Ablation; Intermediate: Resection; Locally advanced: Resection / TACE
- ECOG 0–1, Child A/B, EVM present → Systemic therapy
- ECOG 2–4 or Child C → Early: Liver transplantation; Intermediate/advanced: Supportive care
How to read these staging diagrams: start with tumour number/size and vascular or extrahepatic spread, then integrate liver reserve and performance status. The final therapy is not determined by tumour anatomy alone; transplantation eligibility, portal hypertension, comorbidity and patient goals can move an individual away from a diagram's default branch.
Case from lecture [1]: M/40 with alcohol cirrhosis, status post living donor liver transplant (LDLT), found to have critical stenosis at hepatic artery anastomosis.
Options: (1) Re-exploration (open surgery), or (2) IR – hepatic artery angioplasty + stenting (5mm vascular stent)
The serial angiograms show a thread-like anastomotic narrowing before treatment, balloon dilatation/stent deployment across the lesion and brisker graft arterial flow afterward. This illustrates IR's role in managing post-transplant vascular complications minimally invasively, but also why close transplant-team coordination is needed: dissection, thrombosis, rupture or restenosis can threaten the graft.
Ablation Techniques
The lecture extensively covers percutaneous ablation, which has expanded from liver alone (2015) to liver, kidney, bone, soft tissue tumour, thyroid, and lung by 2020 [1].
| Device | Mechanism | Advantages | Disadvantages |
|---|---|---|---|
| Radiofrequency Ablation (RFA) | Alternating current → ionic excitation → frictional heating → coagulative necrosis. Patient completes the electrical circuit (needle tip = small surface area → high energy concentration → tumour necrosis; grounding pad = large surface area → low energy concentration → minimal skin burn) [1] | Most evidence, fast | Heat sink effect (blood vessels carry away heat → incomplete ablation near large vessels); incomplete ablation in large tumours |
| Microwave Ablation (MWA) | EM field alternates → water molecules try to align ("rock") → dielectric heating → heat [1] | Rapid heating, larger zones, no grounding pad and less susceptibility to perfusion-mediated heat loss than RFA | Still affected by tissue and vessel context; rapid/larger heating can injure adjacent organs |
| Cryoablation | Rapid cooling → intra/extracellular ice and osmotic injury; thaw adds microvascular injury. Protocol commonly uses repeated freeze–thaw cycles [1] | Ice ball is visible on CT, enabling margin monitoring; multiple probes can shape a zone and treatment can be less painful | Lethal isotherm lies inside visible ice edge; anaesthesia needs vary; longer treatment, bleeding and rare systemic cryoreaction |
| High Intensity Focused Ultrasound (HIFU) | Focused US energy → thermal coagulative necrosis, with cavitation and vascular effects | Non-incisional/transcutaneous and no needle tract | Long treatment; access is limited by acoustic window, motion, skin/bowel/bone and target depth; anaesthetic needs vary |
| Percutaneous Ethanol Injection (PEI) | Chemical destruction by absolute alcohol | Simple, cheap | Limited to small tumours |
| Irreversible Electroporation (IRE) | Electrical pulses → permanent cell membrane disruption | Preserves connective tissue scaffolding | Requires GA, cardiac synchronization |
Heat Sink Effect – Must Know
The heat sink effect is an important limitation of RFA. Blood flowing through adjacent vessels carries thermal energy away from the ablation zone and can leave viable marginal tumour. MWA is generally less susceptible, but it is not independent of blood flow and does not eliminate the need to check the margin.
| Temperature | Effect |
|---|---|
| 46–60°C | Cellular damage after prolonged exposure |
| 60–100°C | Instant protein coagulation and irreversible cellular damage |
| > 100°C | Tissue fluid boiling, vaporisation, and carbonisation (carbonised tissue and gas act as insulator → limits further ablation) |
- Ablation zone should cover the tumour plus a 5–10 mm margin (analogous to surgical resection margin)
- Usual ablation zone diameter: ~3–5 cm
- Reality: ablation zone is more elliptical and ~5–10% smaller than manufacturer specifications
How to read the procedure images [1]:
- Plan a path that covers the tumour and margin while avoiding bowel, diaphragm, nerves and vessels.
- Use CT/US, fusion imaging or CEUS to place one or more probes; fusion US registers live ultrasound with prior CT/MRI when a lesion is inconspicuous.
- Create separation with hydrodissection, pneumodissection or artificial ascites when an organ is too close. In the illustrated post-Whipple liver-metastasis case, artificial ascites displaced adjacent viscera before MWA.
- During cryoablation, the CT-visible ice ball is monitored, remembering that its outer rim is warmer than the lethal zone.
- Immediate echogenic gas after thermal ablation shows heating, not necessarily complete tumour kill. Technical success requires appropriate contrast-enhanced imaging and later surveillance for residual/recurrent enhancement.
- Day procedure, LA/sedation, US guidance
- Hydrodissection / perithyroidal infusion to protect surrounding structures
- Results: mean volume reduction 84.11%, therapeutic success 91.6%, complete disappearance 28%
- Complications: total 3.3%, major 1.4%
- Minor: haematoma, transient hoarseness, skin burn
- Major: persistent hoarseness, vessel injury, abscess/haematoma requiring surgery
Comparison: Ablation vs Thyroidectomy [1]:
| Feature | Thyroidectomy | Ablation (RFA) |
|---|---|---|
| Cure rate | Higher, immediate | Lower (may need retreatment) |
| Cancer treatment | Can treat cancer | Limited role |
| Cosmesis | Longer scar | Better cosmesis |
| Thyroid function | Depends on extent; total thyroidectomy requires replacement | Usually preserves functioning thyroid tissue |
| Morbidity | Risks include bleeding, recurrent laryngeal nerve injury and hypocalcaemia | Risks include bleeding, voice change, skin burn and nodule regrowth |
| Hospital stay | Depends on operation and pathway | Often a day procedure |
| Mortality | The slide quotes a historical aggregate figure that should not be applied to an individual | Very low in selected patients |
Current-practice correction: thyroid ablation
ATA guidance supports thermal ablation primarily for properly evaluated benign nodules causing compressive/cosmetic symptoms, and for selected autonomously functioning nodules [15]. Benignity normally requires appropriate ultrasound assessment and cytologic confirmation. It is not a generic substitute for thyroid cancer surgery, and the slide's fixed volume-reduction, complication and surgical mortality figures should not be used as universal counselling estimates.
- Renal cell carcinoma (T1a < 4 cm) — alternative to partial nephrectomy in elderly/comorbid patients [6]
- Painful bone metastases — palliative pain relief
- Bone and soft tissue tumours
- Hydrodissection: injecting fluid (saline/D5W) to create a buffer zone between the ablation target and adjacent structures
- Pneumodissection: injecting air/CO₂ for the same purpose
- Artificial ascites: injecting fluid into the peritoneal cavity to separate liver tumours from adjacent bowel or diaphragm
- CEUS (contrast-enhanced ultrasound) localization: using microbubble contrast to identify the tumour in real time during ablation
- The choice of fluid matters near electrically active probes: non-ionic D5W is commonly preferred for RFA hydrodissection, whereas saline can conduct current.
Wednesday – Musculoskeletal IR
Guidance modalities:
- US: real-time, best for soft tissue
- CT: precise localization, deep structures, bone
- Fluoroscopy: real-time with 3D views / DynaCT capability
Critical concept: Biopsy approach must follow surgical anatomy [1]:
- For a shoulder mass: biopsy through the anterior deltoid
- Avoid the deltopectoral groove (contains the cephalic vein, crucial for surgical approach)
- Avoid the posterior deltoid/neurovascular bundle (axillary nerve, circumflex humeral vessels)
- The biopsy tract must be planned so it can be excised en bloc with the tumour at definitive surgery (this is the Enneking principle)
- Target the viable, enhancing solid portion rather than a necrotic centre, cross as few tissue compartments as possible, and agree the tract with the tumour surgeon before biopsy.
What the CT-guided examples show [1]: a skin grid provides a reproducible entry point; sequential images confirm needle trajectory and depth. Positioning (supine/prone) is chosen to create the safest route. The cervical, acetabular and abdominal-wall cases show that the shortest route is not always safest—bowel, lung, pleura, cord, major vessels and the definitive surgical field determine the path.
Case examples from lecture [1]:
- M/36 left shoulder mass → biopsy through anterior deltoid
- M/35 neck pain with cervical spine lesion → biopsy revealed plasmacytoma
- F/40 left acetabular lytic lesion → prone position biopsy
- 28/F lytic C6 tumour
- F/44 left abdominal wall desmoid tumour → treated with RFA using hydro- and pneumodissection to separate bowel; follow-up images show contraction of the ablation zone. This is a case illustration, not a universal first-line desmoid algorithm; contemporary management may include observation, systemic treatment, ablation or surgery according to symptoms, growth and morbidity.
Vertebroplasty/cementoplasty injects radiopaque PMMA to stabilize selected painful, mechanically unstable osseous lesions. It is not a general treatment for every compression fracture and PMMA should not be described as reliably reducing a vertebral bulge, preventing burst fracture or providing meaningful antitumour therapy.
Mechanism of pain relief: mechanical stabilization reduces painful micromotion. PMMA polymerization is exothermic and may have local chemical/thermal effects, but the lecture's “thermal destruction of pain nerves” is a proposed contributor rather than the sole established mechanism.
Cement (PMMA) [1]:
- Radio-opaque
- Powder + monomer mixture
- Exothermic polymerization: liquid → paste → solid
- Instruments: 8, 10, 12G needles; syringe; cement mixture device
Indications for vertebroplasty [1]:
- Painful bone tumour (metastasis, myeloma, lymphoma)
- Aggressive vertebral haemangioma
- Osteoporotic fracture
- Kümmel's disease (avascular necrosis of vertebral body → delayed vertebral collapse)
Current-practice correction: osteoporotic vertebral fracture
NICE recommends vertebroplasty/kyphoplasty only for severe ongoing pain from a recent, unhealed vertebral fracture despite optimal analgesia, when examination and imaging confirm that fracture as the pain source [16]. Check posterior wall integrity, canal compromise, infection, bleeding risk and whether another diagnosis explains the pain. Cement leakage may be asymptomatic or cause neural injury, pulmonary embolization or adjacent-structure damage; infection and haemorrhage are additional risks.
What the procedural sequence shows [1]: large-bore needle access is placed under image guidance (often transpedicular, sometimes bilateral), position is confirmed in more than one plane, and viscous cement is injected slowly under continuous fluoroscopy. Stop if cement approaches the posterior cortex, venous plexus or disc. Post-procedure CT in the lecture demonstrates cement distribution and checks for leakage.
Post-procedure care [1]:
- Prone until cement hardens
- Bed rest 1–2 hours
- CT to check cement distribution
- Pain score (VAS)
- Discharge next day
Cementoplasty in other locations [1]:
- Acetabulum, femoral condyles, tibial ends, talus and calcaneus
- Combined with ablation (e.g., cryoablation) and/or RT for consolidation of impending pathological fractures
Thursday – Neuro IR
Case: M/83, PMH of AF and hyperlipidaemia, presented with sudden left-sided weakness.
Options [1]:
- Systemic thrombolysis (IV rtPA)
- Mechanical thrombectomy for an eligible large-vessel occlusion; do not withhold IV thrombolysis when otherwise eligible
The lecture shows pre- and post-thrombectomy angiographic images demonstrating successful recanalization.
Current workflow: Perform non-contrast CT to exclude haemorrhage and CTA to identify proximal occlusion. NICE recommends thrombectomy as soon as possible within 6 hours for eligible anterior-circulation LVO, with IV thrombolysis if indicated; selected patients 6–24 hours from last known well may undergo thrombectomy when advanced imaging shows salvageable tissue [17]. Posterior-circulation decisions and imaging criteria require specialist stroke/neurointerventional assessment. The angiograms show absent flow before retrieval, a stent retriever containing clot, and restored arterial filling afterward; angiographic recanalization does not guarantee clinical recovery.
Thrombectomy device evolution [1]:
- 1st generation: coil-like retrieval devices
- 2nd generation: mesh/stent-like retrieval devices (e.g., stent retrievers)
- 3rd generation: devices such as pREset, ERIC, Embotrap, 3D, Aperio, Phenox CRC
Case: 59/F with sudden severe headache. The lecture's non-contrast CT actually shows a deep intracerebral haemorrhage, not the classic basal-cistern pattern of subarachnoid haemorrhage. That distinction changes the reasoning: investigate for a macrovascular cause when the patient's age, haemorrhage location, history and CTA/MRA findings make one plausible [18].
Next investigation in this case: CTA Head is a rapid non-invasive screen for aneurysm or other vascular lesion [1]. Catheter DSA offers higher spatial/temporal detail and may be required when CTA is suspicious or negative despite high clinical suspicion, or when treatment planning demands it; it is not automatically the first test for every severe headache.
Differential options presented in lecture [1]: (1) Digital subtraction angiogram, (2) MRI and MRA Head, (3) Whole body PET scan, (4) CTA Head — CTA is the correct answer.
Case progression: Giant ICA terminus aneurysm → treated with an endovascular occlusion strategy. The serial images include assessment of collateral supply, packing with coils and parent-artery occlusion rather than simply filling a small sac. Treatment of giant aneurysms is individualized; balloon test occlusion, flow-diversion, adjunctive devices or microsurgery may be considered according to anatomy and rupture status.
For a contralateral small cavernous aneurysm: also treated with coil occlusion. In some cases, parent vessel occlusion with balloon test occlusion (PBO) is performed.
Complications of coil embolization [1]:
| Complication | Mechanism |
|---|---|
| Thromboembolic | Clot formation on coil ball/catheter; pushing clot out of aneurysm |
| Aneurysm rupture | More likely in already-ruptured aneurysms |
| Device malfunction | Premature detachment of coil; unravelling |
| Vascular damage | Spasm, dissection |
Thoracic Endovascular Aortic Repair (TEVAR) and Fenestrated EVAR [1]
Case: M/71, 2012 thoracic aortic aneurysm → open aortic replacement (T4–9). 2016 recurrent aneurysm at thoracolumbar junction.
Treatment: 1st TEVAR → 2nd TEVAR → 4-fenestrated EVAR (3 aortic stents + 4 visceral stents) [1]
Why fenestrated? Standard endovascular stent grafts cover the aorta but can occlude vital branch vessels (coeliac, SMA, renal arteries). Fenestrated grafts have custom-made holes (fenestrations) aligned with these branch vessels, allowing stents to be placed through the fenestrations into the branches → maintains visceral perfusion while excluding the aneurysm.
This complex procedure required 3 radiologists + 1 cardiothoracic surgeon + 1 anaesthetist, 10 hours in the angiosuite [1].
What the serial images show [1]: recurrent thoracoabdominal aneurysmal degeneration below prior open repair; staged thoracic endografts create a proximal seal; the custom fenestrated graft is oriented so coeliac, SMA and both renal openings can be catheterized and bridged with covered stents; final angiography checks branch patency, exclusion of the sac and endoleak. This complexity explains the multidisciplinary planning and long procedure. Endovascular repair trades a laparotomy/thoracotomy for risks including endoleak, branch occlusion, spinal-cord ischaemia, renal injury and later reintervention, so lifelong imaging surveillance is essential.
Weekend – Urgent/Emergency Cases
Scenario: 50-year-old man with stones disease, hypotension and tachycardia 4 hours after PCNL.
Most likely cause of haematuria: PCNL-related [1] — iatrogenic vascular injury during percutaneous nephrostomy tract creation.
Finding: Pseudoaneurysm on angiography → treated with selective embolization
This is a classic IR emergency: resuscitate and correct major coagulopathy while localizing active bleeding. CTA may demonstrate a pseudoaneurysm or arteriovenous fistula; selective renal angiography confirms the culprit branch and allows targeted embolization with maximal preservation of renal parenchyma. Surgical re-exploration remains a rescue option if endovascular control fails or is unavailable.
Scenario: 42-year-old woman, 2–3 weeks RLQ pain, now fever and vomiting.
Investigation: CT scan of the abdomen (or USS) → large cystic mass adjacent to caecum = appendix abscess
Lecture case management: CT-guided drainage of the abscess + antibiotics [1]. The images show the planned window into a well-formed collection, guidewire/catheter placement and collapse of the cavity after drainage.
Current-practice correction: appendiceal abscess
Antibiotics with percutaneous drainage when accessible are a valid approach, especially where advanced laparoscopic expertise is unavailable. However, WSES guidance also considers laparoscopic surgery a safe alternative in experienced hands [20]. Routine interval appendicectomy is not mandatory after successful non-operative management in young adults and children; reserve it for recurrent symptoms. In patients aged 40 or older, WSES suggests colonoscopic and interval contrast-CT evaluation because appendiceal neoplasm is more common in this group [20].
Scenario: 58-year-old woman with recurrent pyogenic cholangitis (RPC), fevers/chills/rigors, high WCC, deranged LFTs.
CT findings: Dilated intrahepatic ducts + multiple hypodense liver abscesses [1]
Management progression:
- IV antibiotics → fever did not settle
- PTBD (percutaneous transhepatic biliary drainage) attempted → during the procedure, blood noted draining from catheter, Hb dropped by 1 g/dL
- CT showed blood in the biliary tree (haemobilia)
- Next step: Hepatic arteriogram ± embolization [1]
- Left hepatic arteriogram showed extravasation and contrast staining
- Embolization of the left hepatic artery with gelfoam was performed successfully
Key teaching point: Blood from a biliary drain, haemoglobin fall or shock after transhepatic intervention should raise concern for haemobilia/vascular injury. Resuscitate, check catheter position and obtain urgent vascular imaging; hepatic arteriography can both locate and selectively embolize arterial extravasation or pseudoaneurysm. In the images, contrast first extravasates from a left hepatic branch and disappears after temporary Gelfoam embolization. Surgery is a backup, not an option that can be dismissed categorically.
| Category | Procedures |
|---|---|
| Arterial | Balloon angioplasty and stenting; thrombolysis; haemorrhage control and embolization |
| Venous | Central venous access (e.g., PICC, dialysis catheter); IVC filter; fistula intervention |
| Endovascular IR [2] | Creation of vascular access; stop bleeding (GI, GU, head & neck); open blockages (stroke, PE, renal artery stenosis); treat vascular abnormalities (aneurysms, fistulae, AVMs); treat hypervascular cancers (HCC); treat benign hypervascular diseases (fibroids, BPH, varicocele) |
- CT-guided lung biopsy is the classic example
- Also: liver biopsy (US-guided), renal biopsy, bone biopsy (CT/fluoroscopy-guided)
- Choose fine-needle aspiration or core biopsy according to the tissue and pathology question; accuracy and complication rates depend on organ, lesion, needle, operator and reference standard, so the slide's generic “80–95% accuracy, < 2% complications” should not be applied across all biopsies.
- The lung-biopsy images emphasize a short pleural path and post-procedure assessment for pneumothorax/haemorrhage; liver-biopsy images emphasize a safe intercostal/subcostal window and avoidance of major vessels.
Before any IR procedure:
- Review CBC/coagulation tests when indicated and manage antithrombotic drugs according to the specific procedure's bleeding risk, urgency and patient factors—there is no single laboratory threshold for every IR procedure [19]
- Confirm fasting only when required by the planned sedation/anaesthesia and local policy [3]
- Obtain informed consent [3]
- Assess renal function and contrast risk when iodinated contrast is planned
- Check relevant infection, allergy and pregnancy risks; arrange antibiotics, anaesthetic support and post-procedure observation as appropriate
- Direct communication with radiologist on-call [3]
- Know your patient — clinical context is essential for choosing the right procedure [3]
Integration with Related Material
Per Prof TT Cheung's HCC lecture [5] and Maksim Surgery Notes [5]:
- TACE is a commonly used liver-directed option in selected BCLC intermediate-stage disease; intent and sequencing are individualized
- HKLC staging is more aggressive and may recommend TACE even in some patients who would get best supportive care under BCLC
- Post-lipiodol CT may show oil retention, but viable enhancement on multiphasic imaging is more important for response assessment
- Curative options: resection, local ablation, liver transplant
Per Maksim Surgery Notes [8]:
- IR mesenteric angiogram enables super-selective catheterisation and embolisation for GI bleeding
- Embolic agents:
- Temporary: absorbable gelatin sponge (Gelfoam) — useful but higher rebleeding rate
- Permanent: coils (most effective), particles (for bleeding tumours, risk of bowel ischaemia), liquid agents e.g., NBCA
Past paper Q2 (2020) [9]: A 45-year-old lady with carcinoma of cervix and hydronephrosis → answer is percutaneous nephrostomy. This is a classic IR procedure for obstructive uropathy.
Per Block A VTE lecture [10]: IVC filters have a limited role, principally when acute VTE carries PE risk and anticoagulation is contraindicated. If a retrievable filter is used, arrange follow-up and remove it once protection is no longer needed and retrieval is feasible; not every filter is temporary, and retrieval difficulty increases with dwell time.
Per Ryan Ho Urogenital [6]: T1 RCC (< 4 cm) in elderly/comorbid patients → local ablation (RFA, cryoablation) or active surveillance is an alternative to partial nephrectomy.
Exam Intelligence
- TACE selection — tumour distribution, portal flow and hepatic reserve; recognize that the lecture's three “absolute” exclusions are historical simplifications
- PAE vs TURP — minimally invasive/recovery and sexual-function trade-offs versus magnitude, durability and retreatment; neither has zero adverse effects
- UFE selection — symptomatic fibroids, MRI mapping, bilateral embolization and careful fertility counselling
- Percutaneous nephrostomy — for obstructive uropathy with deteriorating renal function
- Image-guided abscess drainage — source control when a safe window exists; surgery remains an alternative for appendiceal abscess
- Heat sink effect — why RFA may fail near blood vessels; MWA is less susceptible, not immune
- Vertebroplasty selection — concordant severe pain from an appropriate lesion/fracture, balanced against cement leakage and neural/embolic risks
- Embolization for post-procedural bleeding — post-PCNL pseudoaneurysm
- Stroke thrombectomy — for large vessel occlusion
| Trap | Correct Understanding |
|---|---|
| Confusing "embolization" for "embolism" | Embolization = therapeutic occlusion of a vessel; embolism = pathological occlusion |
| Treating future fertility and current pregnancy as the same issue | Do not perform elective UAE during viable pregnancy; future fertility is an uncertainty requiring MDT counselling, not an automatic universal ban |
| Memorizing one absolute TACE list | Portal-vein invasion, extrahepatic disease and poor reserve alter benefit/risk, but current selection is individualized |
| Believing RFA and MWA are identical | RFA is more susceptible to heat sink; MWA is less susceptible but still requires margin assessment |
| Applying one coagulation cutoff to every biopsy | Bleeding-risk category, target organ, urgency, medications and patient physiology determine preparation |
High Yield Summary
-
Interventional Radiology = minimally invasive, image-guided diagnosis and therapy ("pinhole surgery").
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Match the image to the task: angiography for vessel mapping and embolization, US/CT for a safe percutaneous path, cone-beam CT/fusion/CEUS for difficult target localization.
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Recognize the recurring workflow: define target → plan a safe route → protect non-target structures → treat to an imaging endpoint → check complications and arrange surveillance.
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Key procedures: PAE/UAE, TACE, angioplasty/stenting, thermal ablation, image-guided biopsy/drainage, vertebroplasty, thrombectomy/coiling, EVAR and embolization for haemorrhage.
-
Do not memorize lecture-era absolutes as current rules: use multidisciplinary selection, procedure-specific haemostasis thresholds and contemporary disease guidance.
Active Recall - Interventional Radiology
[1] Lecture slides: GC 014. How can interventional radiology help patient management.pdf [2] Lecture slides: IR 2025_VLau.pdf (Contents, Endovascular IR scope) [3] Lecture slides: GC 013. Emergency radiology.pdf (p3, urgent request checklist) [4] Senior notes: Ryan Ho Diagnostic Radiology.pdf (p78–79, IR section) [5] Senior notes: Maksim Surgery Notes.pdf (p125, HCC staging and TACE) [6] Senior notes: Ryan Ho Urogenital.pdf (p148, RCC management including cryoablation) [7] Lecture slides: GC 087. Sudden hemiplegia dysphagia.pdf / Cererbrovascular disease.pdf (stroke management context) [8] Senior notes: Maksim Surgery Notes.pdf (p79, embolization for GI bleeding) [9] Past papers: 2020 Fourth Summative Assessment MCQ paper.pdf (Q2, percutaneous nephrostomy) [10] Senior notes: Block A - Leg swelling and chest pain_ deep vein thrombosis; pulmonary embolism; Thrombophilia.pdf (p26, IVC filter) [11] NICE. Prostate artery embolisation for lower urinary tract symptoms caused by benign prostatic hyperplasia (HTG469): https://www.nice.org.uk/guidance/htg469/chapter/1-Recommendations [12] NICE. Uterine artery embolisation for fibroids (HTG240): https://www.nice.org.uk/guidance/HTG240/chapter/1-recommendations [13] Reig M, et al. BCLC strategy for prognosis prediction and treatment recommendation: The 2022 update. J Hepatol. 2022: https://pmc.ncbi.nlm.nih.gov/articles/PMC8866082/ [14] AASLD Liver Fellow Network. Hepatocellular Carcinoma Locoregional Therapies: https://www.aasld.org/liver-fellow-network/core-series/clinical-pearls/hepatocellular-carcinoma-locoregional-therapies [15] American Thyroid Association. General Principles for the Safe Performance, Training, and Adoption of Ablation Techniques for Benign Thyroid Nodules (2023): https://www.thyroid.org/ablation-techniques/ [16] NICE. Percutaneous vertebroplasty and percutaneous balloon kyphoplasty for treating osteoporotic vertebral compression fractures (TA279): https://www.nice.org.uk/guidance/ta279/chapter/1-Recommendations [17] NICE. Stroke and transient ischaemic attack in over 16s: diagnosis and initial management (NG128), thrombectomy recommendations: https://www.nice.org.uk/guidance/NG128/chapter/recommendations [18] Greenberg SM, et al. 2022 Guideline for the Management of Patients With Spontaneous Intracerebral Hemorrhage. Stroke. 2022: https://www.ahajournals.org/doi/10.1161/STR.0000000000000407 [19] Patel IJ, et al. Society of Interventional Radiology Consensus Guidelines for the Periprocedural Management of Thrombotic and Bleeding Risk in Patients Undergoing Percutaneous Image-Guided Interventions—Part II. JVIR. 2019: https://pubmed.ncbi.nlm.nih.gov/31229333/ [20] Di Saverio S, et al. Diagnosis and treatment of acute appendicitis: 2020 update of the WSES Jerusalem guidelines. World J Emerg Surg. 2020: https://pmc.ncbi.nlm.nih.gov/articles/PMC7386163/
GC013 Emergency Radiology
Emergency radiology is the subspecialty of radiology focused on the rapid interpretation of imaging studies to diagnose acute, life-threatening conditions such as trauma, stroke, and vascular emergencies in urgent clinical settings.
GC015 Imaging Of The Head And Neck
Diagnostic imaging of the head and neck encompasses radiographic, CT, MRI, and ultrasound techniques used to evaluate structures such as the brain, sinuses, orbits, salivary glands, thyroid, vasculature, and aerodigestive tract for pathology.