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Part 2 book “Abdominal imaging” has contents: Genitourinary system, hepatobiliary system, gynaecological disorders, miscellaneous disorders, abdominal aneurysm, abdominal hernias, common paediatric tumours – neuroblastomas, congenital renal anomalies, necrotising enterocolitis,… and other contents.
Genitourinary system chapter The genitourinary system consists of the renal tract and in males includes the reproductive organs such as the prostate, seminal vesicles and testes The kidneys are responsible for filtering the blood and extracting waste products that are excreted into the urinary bladder via the ureters Disorders of the kidneys such as cancer may produce haematuria (blood in the urine), whereas poor renal function leads to elevation of serum creatinine and urea levels Some common diseases affecting the renal tract are urolithiasis (renal stones) and chronic renal failure In younger patients testicular torsion may present as an emergency US is commonly the initial imaging modality used in the evaluation of the renal tract It is also particularly useful for evaluating the scrotal sac CT plays an important role in diagnosis and staging of renal cancer and renal trauma 5.1 Renal artery stenosis Renal artery stenosis (RAS) is the most common cause of secondary hypertension It is defined as narrowing of the lumen of the renal artery and is most commonly (two thirds) caused by atherosclerotic disease Fibromuscular dysplasia is the second most common cause of RAS Patients usually present with very high blood pressure or acute onset of hypertension A vascular bruit (turbulent flow noise) may be felt or heard in the flanks/abdomen Key facts • Atheromatous plaques and calcification typically occur at the origin or within 2 cm of the origin of the renal artery from the aorta • Atheromatous RAS affects older men (usually >50 years), and is bilateral in 30% of cases 114 Genitourinary system • Fibromuscular dysplasia is an autosomal dominant disorder affecting younger patients (more often female), causing medial hyperplasia (middle layer) of the arterial wall • The area of narrowing is usually in the mid or distal renal arteries and is bilateral in two thirds of cases Radiological findings CT or MR angiography Along with traditional catheter angiography, CTA or MRA may be used to delineate the renal vasculature and detect areas of narrowing Doppler studies can be carried out to assess blood flow velocities through the renal arteries (see Figure 1.19) Angiography (CT, MR or catheter) Atheromatous stenosis is usually seen as eccentric areas of narrowing at or near the origin of the renal arteries (Figure 5.1) In patients with fibromuscular dysplasia, multiple narrowings are in the mid to distal renal arteries forming a ‘string of beads’ appearance (Figure 5.2) US with doppler There is an increase in the systolic peak velocity of blood flow through the renal arteries A peak velocity >200 cm/s signifies severe (50–99%) occlusion whereas velo cities between 100 and 200 cm/s are consistent with modest stenosis (100 cm/s) Treatment RAS may be dilated by balloon angioplasty (PTRA or percutaneous transluminal renal angioplasty) Surgical revascularisation has the best success rate in treating renal artery stenosis 5.2 Renal cell carcinoma Renal cell carcinoma (RCC) arises from the tubular epithelium of the kidney and is also known as hypernephroma It is the most common primary renal tumour (85%) and quite often detected incidentally on CT or US Symptoms typically include haematuria, flank pain or palpable masses Key facts • RCC is associated with congenital conditions such as von Hippel–Lindau syndrome and tuberous sclerosis 115 116 Genitourinary system • Distant metastases may be the first presenting sign of RCC and the classic triad of haematuria, flank pain and mass is present in