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AN54.1-4 | Radiodiagnosis — Part 2

Barium Studies — GI Tract Imaging (AN54.3)

Barium sulfate is swallowed or introduced rectally to coat the mucosal surface and reveal detail of the GI tract. Single-contrast (barium only) or double-contrast (barium + air insufflation — better mucosal detail).

Barium Swallow:
Patient swallows barium under fluoroscopy. Evaluates: pharynx, oesophagus, gastro-oesophageal junction.
Indications: dysphagia, oesophageal stricture, achalasia, pharyngeal pouch, hiatus hernia, carcinoma of oesophagus.
Key findings: bird-beak appearance (achalasia), rat-tail narrowing (carcinoma), mucosal irregularity, reflux.

Barium Meal:
Evaluates stomach and duodenum (1st–3rd parts).
Key findings: Barium niche (ulcer crater), filling defect (tumour), deformity of duodenal cap (cloverleaf deformity in chronic duodenal ulcer disease), mucosal pattern.

Barium Enema:
Barium introduced per rectum. Evaluates colon (large intestine from rectum to caecum).
Double-contrast technique preferred for mucosal detail.
Key findings: apple-core (napkin-ring) lesion = colonic carcinoma; thumbprinting = ischaemic colitis or inflammatory bowel disease; diverticular disease (outpouchings); strictures.

Cholecystography (Oral Cholecystogram):
Oral contrast is absorbed from gut → excreted in bile → concentrates in gall bladder (if functioning). Now largely replaced by ultrasound. Still asked in exams.
Assesses: gall bladder function, radiolucent gallstones (filling defects).

Intravenous Pyelography (IVP / IVU):
IV iodinated contrast excreted by kidney → visualises pelvicalyceal system, ureter, urinary bladder.
Key images: nephrogram (parenchyma), pyelogram (collecting system), ureterogram, cystogram.
Key findings: hydronephrosis (delayed drainage, dilated pelvicalyceal system), filling defects (stone, tumour), ureteric deviation, bladder outline.
Now supplemented/replaced by CT KUB (CT urogram) for stone disease.

Hysterosalpingography (HSG):
Iodinated contrast injected through cervix → opacifies uterine cavity and fallopian tubes → spills into peritoneum if tubes are patent.
Indications: infertility workup (tubal patency assessment), intrauterine pathology (fibroids, polyps, septum), Asherman syndrome.
Key findings: tubal block (contrast doesn't spill), uterine filling defects, tubal hydrosalpinx.

ERCP, CT Abdomen, MRI, and Arteriography (AN54.4)

ERCP (Endoscopic Retrograde Cholangio-Pancreatography):
Combines endoscopy + fluoroscopy. Endoscope passed to second part of duodenum → cannulate the ampulla of Vater → inject contrast → outline biliary tree and pancreatic duct.
Diagnostic + therapeutic: remove CBD stones (sphincterotomy + stone extraction), place stents for biliary strictures, biopsy ampullary tumours.
Key findings: CBD stone (filling defect), biliary stricture, pancreatic duct dilation or stricture (chronic pancreatitis), cholangiocarcinoma.
Replaced diagnostically by MRCP (non-invasive) but ERCP remains gold standard for therapy.

CT Abdomen:
Multi-slice CT provides rapid imaging of all abdominal structures.
Uses in abdomen: acute abdomen (appendicitis, diverticulitis), trauma (solid organ injury, haemoperitoneum), tumour staging, AAA (abdominal aortic aneurysm), pancreatitis, inflammatory bowel disease.
CT KUB (non-contrast): stone disease — sensitive for calculi >2 mm.
Triple-phase CT liver: plain + arterial + portal venous phases — characterises hepatic lesions (HCC, metastases, haemangioma).

MRI Abdomen:
Superior soft tissue contrast, no radiation. Preferred for:
• MRCP — non-invasive biliary and pancreatic ductal imaging (replaced diagnostic ERCP)
• MRI liver — characterisation of liver lesions (diffusion, T1/T2 characteristics)
• MRI rectum — staging of rectal carcinoma (pre-operative planning — local invasion, lymph nodes)
• MRI pelvis — uterine/ovarian pathology, endometriosis, fistulae

Arteriography (DSA / CT Angiography):
• Coeliac axis angiography — maps hepatic, splenic, left gastric arteries; pre-operative vascular mapping; embolisation for haemorrhage
• Mesenteric angiography — acute GI bleed localisation; mesenteric ischaemia
• Renal arteriography — renal artery stenosis (renovascular hypertension); pre-embolisation for AVM
• Portal venography — portal hypertension assessment, TIPS procedure guidance
• CT angiography (CTA) is now often preferred over DSA for diagnosis.