Clinical imaging: Imaging pathways and interventional radiology

• Imaging pathways: Using Imaging Pathways | Chest Pain, PE and the Aorta | Suspected Cancer — Which Scan? | Breast Imaging | Neck Lumps and Thyroid Nodules | Jaundice and Abnormal Liver Tests | Haematuria, Prostate and Scrotal Problems | GI Bleeding
• Special groups: Imaging Children | Imaging Older and Frail People
• Interventional radiology: Interventional Radiology — Overview | Vascular Interventions | Embolisation for Bleeding | Biopsy, Drainage and Non-vascular Interventions | Interventional Oncology | Before an IR Procedure — Consent, Clotting and Anticoagulants | After an IR Procedure — Monitoring and Complications
• Revision: Imaging Pathways at a Glance | Spot the Diagnosis | Exam-style Scenarios | Key Points | Guidelines and Further Reading

🩻 Imaging pathways and interventional radiology — page 6 of the Clinical Imaging chapter. Most imaging decisions follow well-established pathways — for chest pain, suspected cancer, jaundice, haematuria and bleeding. Following them avoids wasted scans and delays. Interventional radiology now treats many conditions that once needed open surgery — bleeding, abscesses, blocked kidneys and bile ducts, aneurysms and stroke — and ward doctors prepare patients for these procedures and look after them afterwards.
Your four questions for every imaging pathway or IR referral: Which pathway does this patient fit, and what is the first test? How urgently is it needed? For a procedure — is it indicated, consented and safe (clotting, anticoagulants, kidney function, allergy)? Who monitors the patient afterwards, and what complications should they watch for?

Using Imaging Pathways

• Pathways (NICE, RCR iRefer, local protocols) set out the first test, the timeframe and what happens next for common presentations — they reduce variation, radiation and delay.
• Direct-access imaging — GPs can request CT, MRI and ultrasound directly for many suspected cancer and diagnostic pathways.
• Community diagnostic centres — NHS England sites offering imaging, endoscopy and other tests outside acute hospitals.
• Rapid diagnostic centres — for non-specific but concerning symptoms (weight loss, fatigue, abdominal pain, abnormal bloods) — often CT chest, abdomen and pelvis as the first test.
• Suspected cancer pathways — the Faster Diagnosis Standard — cancer diagnosed or ruled out within 28 days of urgent referral.
• Imaging in MDTs — radiologists review imaging in cancer, ILD, vascular and other multidisciplinary meetings.
• Patient preparation and information — explain what the test involves, why, risks, and how results will be given.

Chest Pain, PE and the Aorta

• Acute chest pain — ECG within 10 minutes, high-sensitivity troponin; chest X-ray for alternative diagnoses (pneumothorax, pneumonia, widened mediastinum).
  • STEMI — primary PCI (coronary angiography) — no imaging delay.
  • NSTEMI — angiography within 72 hours (risk-guided); echo for LV function.
• Stable chest pain of suspected cardiac origin (NICE CG95) — CT coronary angiography first line (unless clinical assessment shows non-anginal pain); functional imaging (stress echo, myocardial perfusion scan, stress cardiac MRI) if CTCA is non-diagnostic or shows disease of uncertain significance; invasive angiography if functional imaging is non-diagnostic or for revascularisation.
• Suspected PE (NICE NG158) — two-level Wells score → D-dimer (PE unlikely) or CTPA (PE likely); V/Q if CTPA contraindicated (contrast allergy, severe renal impairment) or in pregnancy with a normal chest X-ray; bedside echo if too unstable for CT (RV dilatation).
• Suspected DVT — proximal leg vein compression ultrasound within 4 hours (interim anticoagulation if delayed).
• Suspected aortic dissection — CT aortogram urgently (TOE if unstable in theatre or ICU).
• Pericardial effusion and tamponade — echocardiography — urgent pericardiocentesis if tamponade.
• Heart failure — NT-proBNP then echocardiogram (within 2 weeks if NT-proBNP over 2,000 ng/L; within 6 weeks if 400–2,000 — NICE NG106).

Suspected Cancer — Which Scan?

Breast Imaging

• NHS Breast Screening Programme — mammography every 3 years for women aged 50 to 71 (and those aged 71 and over can self-refer); about 1 in 10 recalled cancers are interval cancers.
• Higher risk women (family history, BRCA, TP53, chest radiotherapy for Hodgkin lymphoma before 30) — annual MRI and/or mammography from an earlier age (very high risk protocol — see Genetics chapter).
• Symptomatic women (lump, nipple change, skin change) — triple assessment in a one-stop clinic:
  1. Clinical examination.
  2. Imaging — mammography (usually 40 and over) plus ultrasound; ultrasound alone under 40 (dense breasts, radiation).
  3. Biopsy — ultrasound- or stereotactic-guided core biopsy (FNA for cysts or nodes).
• Scoring (UK) — 1 (normal) to 5 (malignant) for each modality (M1–M5, U1–U5) — scores of 3 or above need biopsy.
• Breast MRI — high-risk screening, lobular cancer extent, implant integrity, occult primary with axillary nodes, response to neoadjuvant chemotherapy.
• Men — ultrasound for gynaecomastia vs cancer (mammography if suspicious).
• Pregnancy and breastfeeding — ultrasound first; don't dismiss a persistent lump.
• Axillary staging — ultrasound with biopsy of abnormal nodes; sentinel node biopsy.

Neck Lumps and Thyroid Nodules

• Neck lumps:
  • Ultrasound is first line — characterises lymph nodes, thyroid, salivary glands and cysts; guides FNA or core biopsy.
  • Suspected cancer referral (NICE NG12) — unexplained neck lump in people aged 45 and over, persistent unexplained neck lump, unexplained thyroid lump; neck lump with weight loss, night sweats or other lymphoma features.
  • Young adults with tender nodes after infection — usually reactive; reassess at 2–6 weeks.
  • CT or MRI neck — head and neck cancer staging (with PET-CT).
• Thyroid nodules (British Thyroid Association):
  • Ultrasound U-classification — U1 normal, U2 benign (e.g. spongiform, cystic), U3 indeterminate, U4 suspicious, U5 malignant (hypoechoic, microcalcification, irregular margins, taller-than-wide, abnormal nodes).
  • FNA for U3–U5 nodules; cytology graded Thy1–Thy5.
  • Check TSH — if suppressed, thyroid uptake scan ("hot" nodules are rarely malignant).
  • Incidental thyroid nodules on CT, MRI or carotid Doppler — ultrasound if clinically indicated; FDG-avid nodules on PET need assessment.
• Parathyroid adenoma localisation — neck ultrasound and sestamibi scan (or 4D-CT, choline PET) before surgery.
• Salivary gland swelling — ultrasound (stones, tumours, Sjögren's); MRI for tumours.

Jaundice and Abnormal Liver Tests

• Jaundice — ultrasound first — is the biliary tree dilated?
  • Dilated ducts (obstructive) → find the level and cause:
    • MRCP — stones, strictures, cholangiocarcinoma, PSC.
    • Pancreatic protocol CT — pancreatic or ampullary tumour (double duct sign), staging.
    • EUS — small stones, small tumours, biopsy.
    • ERCP — therapeutic (stone extraction, stenting) rather than diagnostic.
    • PTC (percutaneous transhepatic cholangiography) and drainage — hilar obstruction or failed ERCP.
  • Non-dilated ducts → hepatocellular or intrahepatic cholestasis — liver screen bloods (viral serology, autoantibodies, immunoglobulins, ferritin, caeruloplasmin, alpha-1 antitrypsin), drug history, alcohol; MRI or biopsy if unclear.
• Painless jaundice with weight loss in an older adult — pancreatic or biliary cancer until proven otherwise — urgent CT.
• Abnormal liver tests (BSG 2018) — standard liver aetiology screen plus ultrasound; fibrosis assessment in MASLD and alcohol (FIB-4 or ELF, then transient elastography); refer advanced fibrosis or cirrhosis to hepatology.
• Cirrhosis — 6-monthly ultrasound for HCC; endoscopy for varices (or elastography-based criteria).
• Acute liver failure — Doppler ultrasound (hepatic and portal vein patency — Budd–Chiari).
• Right upper quadrant pain with fever — ultrasound (cholecystitis, liver abscess); CT if ultrasound is inconclusive.

Haematuria, Prostate and Scrotal Problems

• Visible haematuria (without UTI, or persisting after treatment) — suspected cancer referral in people aged 45 and over (NICE NG12) — flexible cystoscopy plus upper tract imaging — CT urogram (or ultrasound in lower-risk or younger patients per BAUS guidance).
• Non-visible haematuria — confirm on repeat dipstick, exclude UTI; age 60 and over with dysuria or raised white cell count — suspected cancer referral; ultrasound and cystoscopy; check renal function, BP and ACR (nephrological causes — IgA nephropathy, Alport's).
• Renal colic — CT KUB within 24 hours (see page 3).
• Lower urinary tract symptoms — post-void residual (bladder scan), renal ultrasound if retention, AKI or recurrent infection; imaging isn't routine.
• Suspected prostate cancer — multiparametric MRI before biopsy (NICE NG131) — PI-RADS 3–5 → biopsy (transperineal); PI-RADS 1–2 with low PSA density — may avoid biopsy.
• Scrotal swellings:
  • Testicular torsion — clinical diagnosis — emergency surgical exploration; don't delay for ultrasound.
  • Testicular mass — urgent ultrasound — solid intratesticular mass = cancer until proven otherwise (suspected cancer referral; tumour markers AFP, hCG, LDH; CT staging).
  • Epididymo-orchitis (increased flow), hydrocele (anechoic fluid — ultrasound to see the testis), varicocele (left-sided; new right-sided or non-reducing — image the abdomen for a renal mass), epididymal cyst.
• Recurrent UTI — renal tract ultrasound (structural abnormality, residual, stones) in men and in women with recurrent pyelonephritis or atypical features.

GI Bleeding

• Upper GI bleeding — endoscopy is diagnostic and therapeutic (within 24 hours; immediately after resuscitation if unstable — NICE CG141); CT angiography and interventional radiology embolisation if endoscopy fails or rebleeding occurs (e.g. gastroduodenal artery).
• Lower GI bleeding (BSG 2019):
  • Unstable (shock index over 1 after resuscitation) — CT angiography → catheter angiography and embolisation (ideally within 60 minutes) or endoscopic/surgical treatment.
  • Stable major bleed — admit for colonoscopy.
  • Minor bleed (Oakland score 8 or less) — discharge with outpatient investigation.
  • Exclude an upper GI source (urea raised, haemodynamic instability) — gastroscopy first if suspected.
• Obscure or small bowel bleeding — capsule endoscopy, CT enterography, double-balloon enteroscopy; Meckel's scan (technetium pertechnetate) in children and young adults.
• Haemoptysis (massive) — CT angiography → bronchial artery embolisation.
• Variceal bleeding refractory to endoscopic therapy — TIPS.
• Haemobilia, pseudoaneurysms (pancreatitis — splenic or gastroduodenal artery) — CT angiography and embolisation.

Imaging Children

• Children are more sensitive to radiation and live longer to express its risk — minimise ionising radiation: use clinical decision rules, ultrasound and MRI first where possible, child-specific CT protocols ("Image Gently").
• Ultrasound first for:
  • Appendicitis — non-compressible appendix over 6 mm.
  • Intussusception (6 months–2 years — colicky pain, drawing up legs, "redcurrant jelly" stool) — target sign — air enema reduction.
  • Pyloric stenosis (2–8 weeks — projectile vomiting) — thickened pylorus (muscle over 3 mm, length over 15 mm).
  • Hips (DDH, irritable hip), renal tract after UTI, neonatal brain (cranial ultrasound through the fontanelle), scrotum, neck lumps.
• Bilious vomiting in a neonate — malrotation with volvulus until proven otherwise — urgent upper GI contrast study (or ultrasound) and surgical review.
• Necrotising enterocolitis (preterm infants) — AXR — pneumatosis, portal venous gas, free gas.
• Inhaled foreign body — chest X-ray (often normal; air trapping — inspiratory and expiratory films or decubitus views); bronchoscopy if suspected.
• MRI in children — "feed and wrap" in infants; sedation or general anaesthesia in young children; play specialists.
• Safeguarding imaging — skeletal survey and CT head (see page 5).
• Consent — explain to parents and, where able, to the child; Gillick competence.

Imaging Older and Frail People

• Atypical presentations — low threshold for imaging (CT head after falls on anticoagulants, CT abdomen for vague abdominal pain, occult fractures after falls).
• Proportionality — ask whether the result would change management in the context of frailty, prognosis and the patient's wishes; avoid cascades of investigation for incidental findings that will never cause harm.
• Capacity and consent — assess capacity for interventional procedures; best-interests decisions under the Mental Capacity Act; involve families and advance care plans.
• Practicalities — transport, positioning (kyphosis, contractures), pressure care during long waits, hearing and visual impairment, delirium risk, toileting, continuity of drugs (Parkinson's medication on time).
• MRI tolerance — claustrophobia, inability to lie flat, implants (pacemakers) — consider alternatives.
• Contrast — reduced kidney function is common — check eGFR; hydration.
• Interpretation — age-related changes (atrophy, small vessel disease, degenerative spine, osteopenia, aortic calcification) are common and often not the cause of symptoms.
• Bone health — vertebral fractures on imaging should trigger osteoporosis assessment.

Interventional Radiology — Overview

• Interventional radiology (IR) — minimally invasive, image-guided diagnosis and treatment using needles, wires, catheters, balloons, stents and embolic agents through small skin punctures — usually under local anaesthetic and sedation.
• Advantages — less pain, faster recovery, shorter stays, lower risk than open surgery (especially in frail or unstable patients); can be life-saving in haemorrhage.
• Imaging guidance — fluoroscopy and angiography, ultrasound, CT, cone-beam CT, MRI.
• Access — arterial (common femoral or radial artery), venous (femoral, jugular), percutaneous (direct into an organ or collection).
• Interventional neuroradiology — stroke thrombectomy, aneurysm coiling, AVM embolisation.
• 24/7 IR services — required for major trauma centres and acute bleeding; networked across regions.
• Interventional radiologists see patients in clinic, consent them and manage them on wards — work alongside surgeons in hybrid theatres.

Vascular Interventions

Embolisation for Bleeding

• Embolisation — blocking a bleeding or abnormal vessel through a catheter with coils, particles, glue, plugs or gelatin sponge.
• Emergency uses:
  • Trauma — spleen, liver, kidney, pelvic arterial bleeding (pelvic fractures).
  • GI bleeding — upper GI after failed endoscopy; lower GI (diverticular, angiodysplasia).
  • Massive haemoptysis — bronchial arteries (bronchiectasis, CF, TB, cancer).
  • Postpartum haemorrhage — uterine arteries (when medical and surgical measures fail).
  • Post-procedural bleeding — after biopsy, surgery or PCNL; pseudoaneurysms.
  • Epistaxis (refractory), haematuria from tumours, bleeding renal angiomyolipoma.
• Elective uses:
  • Uterine fibroid embolisation — alternative to hysterectomy.
  • Prostate artery embolisation — benign prostatic hyperplasia (selected).
  • Varicocele and pelvic congestion embolisation.
  • AVMs (including pulmonary AVMs in HHT), aneurysms (visceral, intracranial coiling).
  • Pre-operative tumour embolisation; portal vein embolisation before liver resection.
• Complications — non-target embolisation (ischaemia of other organs), post-embolisation syndrome (pain, fever, nausea), infection or abscess, access site bleeding, contrast effects.

Biopsy, Drainage and Non-vascular Interventions

• Image-guided biopsy (ultrasound or CT):
  • Lung (CT-guided) — pneumothorax is common (about 1 in 5; a chest drain is needed in about 1 in 20), haemoptysis.
  • Liver and kidney (native and transplant) — bleeding is the main risk — check clotting; transjugular liver biopsy if coagulopathy or ascites.
  • Lymph nodes, bone, soft tissue masses (sarcoma — at the specialist centre), breast, thyroid, adrenal (exclude phaeochromocytoma first).
• Drainage:
  • Abscesses (liver, intra-abdominal, pelvic, post-operative, diverticular), empyema, pleural effusions, ascites (paracentesis — usually ward-based with ultrasound), pericardial effusions.
• Urinary:
  • Percutaneous nephrostomy — infected obstructed kidney (emergency), obstruction from tumours or stones, ureteric leaks.
  • Antegrade ureteric stents.
• Biliary:
  • PTC and biliary drainage or stenting — malignant hilar obstruction, failed ERCP, post-surgical leaks.
  • Percutaneous cholecystostomy — acute cholecystitis in patients unfit for surgery.
• GI:
  • Radiologically inserted gastrostomy (RIG) — enteral feeding (e.g. MND, head and neck cancer) when PEG isn't possible.
  • Oesophageal, duodenal and colonic stents — palliation of malignant obstruction (colonic stent as a bridge to surgery in some).
• MSK and spine — joint injections and aspirations, nerve root and facet injections, vertebroplasty or kyphoplasty (painful osteoporotic or malignant vertebral fractures — selected cases).

Interventional Oncology

• Tumour ablation — destroying tumours with heat or cold through a needle probe:
  • Radiofrequency and microwave ablation — small HCC (under 3 cm), colorectal liver metastases, small renal cancers (older or comorbid patients), lung tumours, osteoid osteoma.
  • Cryoablation — renal tumours, some bone and soft tissue tumours.
• Transarterial chemoembolisation (TACE) — intermediate-stage HCC — chemotherapy and embolic particles into the hepatic arterial supply of the tumour.
• Selective internal radiation therapy (SIRT) — yttrium-90 microspheres for liver tumours (selected cases).
• Palliative interventions — stents (biliary, oesophageal, colonic, airway, SVC), nephrostomies, drains for malignant ascites and effusions (indwelling pleural and peritoneal catheters), coeliac plexus block for pancreatic cancer pain, cementoplasty for bone metastases.
• SVC obstruction (lung cancer, lymphoma) — SVC stenting gives rapid symptom relief; obtain tissue diagnosis where possible.
• MDT decisions — IR oncology options are discussed alongside surgery, radiotherapy and systemic therapy.

Before an IR Procedure — Consent, Clotting and Anticoagulants

• Indication and plan — discuss with the IR team; check previous imaging; confirm what the procedure is expected to achieve.
• Consent — usually taken by the operator or a trained member of the IR team (GMC — risks, benefits, alternatives, including doing nothing); assess capacity; best-interests process if lacking capacity.
• Bloods — FBC (platelets), clotting (INR) for higher-risk procedures, U&E and eGFR (contrast), group and save (higher bleeding-risk procedures).
• Bleeding risk (SIR and BSIR guidance — follow local policy):
  • Low-risk procedures (e.g. paracentesis, thoracentesis, superficial biopsy, PICC, dialysis access) — routine clotting tests often not needed; correct only very abnormal values.
  • High-risk procedures (e.g. liver or renal biopsy, nephrostomy, biliary drainage, TIPS, deep biopsies) — typically aim for INR about 1.5 or less (up to 1.8 per some guidance) and platelets over 50 × 10⁹/L.
• Anticoagulants and antiplatelets (balance bleeding against thrombosis risk):
  • Warfarin — usually stop about 5 days before high-risk procedures; bridging with LMWH only for very high thrombotic risk (e.g. mechanical mitral valve).
  • DOACs — stop 1–3 days before (longer with renal impairment, especially dabigatran) for high-risk procedures.
  • LMWH — omit the dose before (prophylactic 12 hours; treatment dose 24 hours).
  • Clopidogrel, prasugrel, ticagrelor — usually stop 5–7 days before high-risk procedures (check with cardiology if recent stents); aspirin is often continued.
  • Restart as advised by the operator (typically 24–48 hours for high-risk procedures).
• Other preparation — fasting if sedation is planned (local policy), IV access, contrast allergy and metformin checks, antibiotic prophylaxis (biliary, urinary, some embolisations), diabetes management, pregnancy test.

⚠️ Safety Pearl: Many IR delays and cancellations are avoidable. For a high-risk procedure, check platelets, INR, kidney function and group and save the day before, and agree with the operator — in writing — when to stop and restart each anticoagulant or antiplatelet.

After an IR Procedure — Monitoring and Complications

• Observations — pulse, BP, oxygen saturation and pain (e.g. every 15 minutes for the first hour, then every 30 minutes, then hourly for several hours — follow the post-procedure instructions).
• Arterial access (femoral or radial):
  • Bed rest for a set period after femoral puncture (shorter with closure devices).
  • Check the puncture site and distal pulses.
  • Complications — groin haematoma (press firmly above the puncture site), pseudoaneurysm (pulsatile mass with bruit — ultrasound; thrombin injection or compression), retroperitoneal haemorrhage (back or flank pain, hypotension, falling Hb with little visible bleeding — CT), arterial dissection or occlusion, AV fistula.
• Organ-specific complications:
  • Lung biopsy — pneumothorax (chest X-ray at 1–4 hours or if symptomatic).
  • Liver or renal biopsy — bleeding (tachycardia, pain, falling Hb, haematuria) — CT angiography and embolisation if significant.
  • Biliary and urinary drainage — sepsis (rigors within hours — blood cultures, IV antibiotics), drain dislodgement, bile or urine leak.
  • Embolisation — post-embolisation syndrome; non-target ischaemia.
  • TIPS — encephalopathy, heart failure.
• Drains and tubes — record output, flush as instructed, secure them; know who to contact if a drain stops working or falls out.
• Contrast — check kidney function in high-risk patients; restart metformin when appropriate.
• Communication — clear post-procedure instructions in the notes (observations, mobilisation, when to eat, anticoagulant restart, follow-up imaging, drain care, results of biopsies).

Imaging Pathways at a Glance

Spot the Diagnosis