Cryptorchidism and Testicular Torsion Cryptorchidism (Undescended Testes) Definition The testis is normally drawn caudad towards the inguinal canal by the gubernaculum, which is attached to its lower pole – differential growth between the gubernaculum and abdominal wall may account for this migration ▪ An undescended testis may be found anywhere along its normal course of descent from the retroperitoneum to the inguinal canal 80% are found…

Urethra: Benign Disorders Congenital Anomalies Müllerian duct cysts Usually the caudal Müllerian duct is obliterated apart from its distal tip (which forms the verumontanum) ▸ incomplete obliteration may lead to the formation of cysts between the bladder and rectum which can present with urinary frequency or obstructive symptoms MRI/US Midline cystic structures which are located within the posterior portion of the prostate gland (superior to the…

Prostate: Benign Disorders Acute and Chronic Prostatitis Definition The same organisms that produce acute prostatitis can cause chronic prostatitis ▪ Healthy adults: E. coli and staphylococci are the predominant causative organisms ▪ Immunocompromised patients: unusual organisms are more commonly seen (e.g. a gonococcal, streptococcal, mycotic or viral aetiology) Voiding cystourethrogram A narrowed, elongated or straightened prostatic urethra If chronic prostatitis is associated with a urethral stricture,…

Miscellaneous Bladder Conditions Congenital Anomalies Bladder agenesis A rare condition which is usually associated with absence of the urethra and other congenital abnormalities ▸ there is marked upper tract dilatation and renal dysplasia which is incompatible with life Bladder hypoplasia (dwarf bladder) This is extremely rare and is usually associated with other urinary tract anomalies Bladder duplication Each bladder receives the drainage from an ipsilateral ureter…

Renal Parenchymal Disease Glomerulonephritis Definition A proliferative and necrotizing abnormality of the glomeruli ▸ it is usually primarily renal but may be part of a systemic vasculitis (e.g. SLE, PAN, Goodpasture's or Wegener's) US/CT/MRI Acute: symmetrically swollen kidneys ▸ no papillary or calyceal abnormality Chronic: small kidneys ▸ smooth, normal pelvicalyceal systems ▸ prominent renal sinus fat Acute tubular necrosis (ATN) Definition Deposition of cellular debris…

Abdominal Wall Defects Omphalocele Definition: incomplete formation of the embryonic ventral abdominal wall leads to a congenital midline anterior abdominal wall defect around the umbilicus (the umbilical cord inserts at the tip of the defect) ▪ Larger omphaloceles (containing liver tissue): these are due to failure of fusion of the lateral body folds ▪ Smaller omphaloceles (containing bowel only): these are due to the persistence of…

Abnormal Gas Distribution Pneumoperitoneum Definition Free intra-abdominal gas – it usually indicates perforation of a viscus (it is often a peptic ulcer – a perforated appendix rarely demonstrates free gas) ▪ Other causes: bowel obstruction ▸ appendicitis ▸ bowel ischaemia ▸ diverticular disease ▸ post colonoscopy Radiological Features Erect CXR Gas is seen under the diaphragm (this can detect as little as 1 ml of free gas)…

Benign Diseases Ascites Definition >100 ml of free fluid within the peritoneal cavity due to benign or malignant causes ▪ Transudative fluid: portal hypertension/cirrhosis/heart failure/nephrotic syndrome ▪ Exudative fluid: infection/peritoneal carcinomatosis ▪ Blood: trauma/tumour rupture/haemorrhagic diathesis ▪ Purulent fluid: intestinal perforation ▪ Others: bile (biliary leakage)/chyle (lymphatic obstruction)/pancreatitis fluid Exudates may be limited by peritoneal reaction/adhesions ▸ transudates diffuse freely Ascites usually seen in the pouch of…

Miscellaneous Splenic Conditions Normal variants and congenital anomalies Splenunculus: this represents ectopic splenic tissue of congenital origin ▸ they can be single or multiple and are usually found at the splenic hilum ▸ they have similar imaging (and enhancement) appearances to the spleen Wandering spleen: this follows laxity of the suspensory ligament ▸ torsion may occur Polysplenia: the spleen is divided into 2–16 masses ▸ this…

Congenital Abnormalities Embryology The pancreas develops in two parts from the endoderm of the primitive duodenum Dorsal part: this is the first part to appear, initially appearing as a diverticulum from the dorsal wall of the duodenum ▸ it forms the neck, body and tail of the gland and part of the head Ventral part: this develops more caudally and initially appears as a diverticulum from…

Methods of Investigation Magnetic Resonance Cholangiopancreatography (MRCP) Technique Heavily T2-weighted coronal oblique fast spin-echo sequence to obtain source data (aligned along the plane of the common bile duct [CBD]) ▪ Stationary water appears as areas of high SI and adjacent soft tissue is low SI (therefore it is not reliant on contrast excretion and can be used in jaundiced patients) ▪ Fasting reduces any unwanted signal…

Anatomy and Imaging Techniques Anatomy Couinaud classification The liver is subdivided anatomically into 8 segments; segments II – VIII are divided anatomically via the portal and hepatic veins The caudate lobe (segment I): this is autonomous, receiving vessels from both the left and right portal vein branches and the hepatic artery ▸ it has an independent venous drainage directly into the IVC Vascular anatomy Blood supply…

Ulcerative Colitis and Toxic Megacolon Ulcerative Colitis (UC) Definition A relapsing and remitting inflammatory bowel disease predominantly involving the colorectal mucosa and submucosa ▸ there is symmetrical colonic involvement (cf. asymmetrical Crohn's disease) It always involves the rectum – any remaining colitis is in continuity with its proximal extent ▪ Proctitis: inflammatory changes limited to the rectum Clinical presentation Bloody diarrhoea (± constitutional symptoms) in young…

Crohn's Disease (CD) Crohn's Disease Definition A chronic progressive transmural granulomatous inflammatory bowel disease There are typically discontinuous (‘skip’) lesions with asymmetrical bowel wall involvement It can affect any part of the GI tract – however it almost always affects the terminal ileum (in 95% of cases) Radiological features Barium studies Bowel wall ulceration ▪ Aphthoid ulcers: characteristic superficial ulcers that do not penetrate the muscularis…

Peptic Ulceration, Gastric Heterotopia, Duodenal Diverticula Peptic Ulceration Definition Mucosal ulceration occurring within an acidic part of the GI tract ▸ it is often associated with H. pylori infection ▸ duodenal ulcers are 2–3x more common than gastric ulcers ▪ Bulbar ulcers (95%): these are usually benign – Location: anterior wall > posterior wall ▪ Postbulbar ulcers (5%): these are usually malignant (95%) and fail to…

Benign Gastric Ulcers Benign Gastric Ulcers Definition Gastric ulcers penetrate the stomach wall through the mucosa and into the submucosa (and frequently also into the muscularis propria) ▸ 95% are benign and they can also be multiple Causes Helicobacter pylori infection (70%) ▸ NSAIDs ▸ alcohol abuse ▸ steroid use ▸ emotional stress ▸ smoking ▸ hereditary factors Radiological features Location Distal stomach > proximal stomach…

Hiatus Hernia and Reflux Hiatus Hernia Definition Protrusion of part of the stomach through the diaphragmatic oesophageal opening ▪ Type 1 – sliding hernia (the commonest type): the gastro-oesophageal junction (GOJ) slides proximally through the diaphragmatic hiatus to assume an intrathoracic position ▸ it is accompanied by reflux and oesophagitis – The squamocolumnar junction is seen at ≤38 cm (the normal is 40 cm) from the incisors at…

Conventional Coronary Angiography and Echocardiography Conventional Coronary Angiography This involves the selective injection of contrast medium into the right and left coronary arteries and the left ventricle (while recording the resultant moving images) Being replaced by non-invasive CCT and CMR Technique A percutaneous femoral arterial catheterization is the usual approach (an alternative percutaneous route is the radial artery) ▸ at least 3 shaped catheters are required…

Gastrointestinal Vascular Disorders Mesenteric Haemorrhage Upper gastrointestinal (GI) haemorrhage This is defined as bleeding proximal to the duodenal–jejunal flexure (most commonly from the left gastric artery) Causes: peptic ulceration ▸ pancreatitis ▸ gastro-oesophageal varices ▸ as a complication of endoscopic, surgical, or percutaneous biliary procedures Lower GI haemorrhage This is defined as bleeding distal to the duodenal–jejunal flexure and is less commonly seen Causes: colonic angiodysplasia…

Aortic Rupture Traumatic Aortic Injury (TAI) Definition This occurs as a result of a rapid deceleration injury generating shearing forces at the aortic isthmus ▸ other mechanisms of injury include an AP compression force displacing the heart to the left (a torsion stress) ▪ Incomplete rupture: the adventitia remains intact (maintaining the aortic integrity) in the majority of survivors ▸ the saccular outpouching that can develop…