Intravascular Contrast Media Barium based contrast agents For assessment of the GI tract Based on very poorly soluble barium sulphate (BaSo 4 ) ▸ administered PO or PR Can lead to barium peritonitis if leaks into the peritoneal cavity Iodine based contrast media For general use in angiography and CT No marked pharmacological actions – can interfere with clotting times (avoid clotting tests for 6 hours…

Obstetric Haemorrhage Fibroid Embolization – Uterine Artery Embolization (UAE) Definition Uterine fibroids are the commonest tumour found in reproductive women – the prevalence increases up to the menopause (up to 80% in Afrocarribean women) You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

Percutaneous Renal Access The safest point for calyceal puncture is the centre of the calyx, approached through the relatively avascular plane (Brödel's line) between the branches of the anterior and posterior divisions of the renal artery Puncturing the centre of the calyx avoids injury to the arcuate divisions that course around the infundibulum – puncture into the infundibulum or renal pelvis may lacerate larger arterial branches…

Liver Biopsy Spring-powered cutting sheath biopsy devices collect more consistent core biopsies with less crush artefact than a manually operated system The traditional route for liver intervention uses a horizontal right lateral intercostal approach ▸ an anterior subcostal approach (that does not traverse the pleura) is less likely to cause pulmonary complications It is preferable to biopsy lesions using a route through intervening normal liver as…

Radiofrequency Ablation (RFA) Monopolar RFA involves the application of high frequency (460-500 kHz) alternating current to the target tissue using a needle like applicator (dispersive grounding pads are attached to the patient's trunk / thigh) ► the resultant alternating electric field around the uninsulated probe tip causes ‘radiofrequency’ agitation of water molecules (inherently polarized) and local frictional heating within a few mm of the probe tip Coagulative…

Chest Pleural drainage catheters are smaller than surgical drains (up to 16Fr) – haemothorax is better treated with surgical drains (36–38Fr) USS is adequate for uncomplicated collections, but CT is usually needed for drainage of multiloculated pleural collections It is recommended that the dependent portion of the collection is accessed just above the adjacent rib (away from the neurovascular bundle) and avoiding insertion close to the…

Multidetector CT Angiography (MDCTA) Rapid IV injection of contrast (3-5 mL/s) ▸ automated contrast bolus detection techniques: the ‘arrival of contrast medium is measured within a vessel at a single level, and data acquisition initiated when a certain density threshold is reached ▪ Multiplanar reconstruction (MPR): useful for the rapid review of blood vessels in any plane (and assessment of vessel walls that might be obscured in…

Catheter Angiography Vascular Access Contraindications Very few absolute contra-indications – caution with patients on anticoagulants / systemic hypertension / prolonged steroid treatment / connective tissue disorders The right common femoral arterial approach is preferred (other sites include the axillary, brachial or radial artery) this allows good access with well defined puncture landmarks and a low complication rate Arterial puncture technique: can use a single (anterior artery…

Positron Emission Tomography – CT (PET-CT) General principles PET imaging is based on the detection of an injected positron-emitting radioactive tracer – PET relies on the co-incidence detection of the annihilation photons (γ) released when a positron combines with an electron; it cannot differentiate individual species that are radiolabelled PET has a high sensitivity but low spatial resolution – PET-CT combines cross sectional anatomic information (CT)…

9 Lymphoma 894 Introduction 894 Lymph node disease in lymphoma 898 CNS lymphoma 900 Pulmonary lymphoma 902 Lymphoma of the gastrointestinal tract 904 Musculoskeletal lymphoma 906 Extranodal manifestations of lymphoma 908 Monitoring the response to therapy in lymphoma 912 Lymphoma Introduction Definition The lymphomas are caused by the malignant clonal expansion of either T or B lymphocytes – these can accumulate within lymph nodes (causing lymphadenopathy)…

Non-Functional Adrenal Disorders Non-Hyperfunctioning Adrenal Adenoma Definition This is due to non-neoplastic overgrowth of the adrenocortical cells of the zona fasciculate More common in some inherited diseases (e.g. MEN 1/Beckwith–Weidman syndrome/Carney complex) It is detected incidentally in up to 5% of CT examinations ▸ the number and size of any nodules increases with age (but generally they are <6 cm in diameter) Most commonly seen in obese…

Thyroid Cancer Thyroid Cancer Definition A malignant tumour arising from the thyroid or parafollicular C cells ▸ it is an uncommon tumour (accounting for 0.5% of all cancer deaths) Risk factors: previous radiation exposure ▸ iodine excess ▸ a genetic predisposition ▸ alcohol excess Clinical Presentation It presents with a painless solitary thyroid nodule ▸ there can be hoarseness (due to recurrent laryngeal nerve involvement), dysphagia…

Mandibular/Maxillary Cystic Lesions General Features Definition Cysts occur more frequently within the jaw than in any other bone due to the numerous epithelial cell residues left after tooth formation ▸ these cysts are slow growing and painless (unless they become infected) Odontogenic cysts These arise from epithelial residues of tooth-forming tissues and include: radicular (dental) and residual cysts ▸ dentigerous cysts ▸ odontogenic keratocysts Non-odontogenic cysts…

Selected Disorders of the Ear External Ear Squamous or basal cell carcinoma HRCT Defines the extent of any bone erosion or destruction MRI Allows precise assessment of the soft tissue mass Necrotizing otitis externa Definition An osteomyelitis/necrosis particularly affecting the floor of the external auditory canal ▸ Pseudomonas is a typical initiating organism It typically affects an elderly diabetic patient and is associated with a facial…

The Orbit Definition Disease processes can be classified according to the anatomical site involved – this is usually in relation to the rectus muscle pyramid (the ‘cone’) Intraconal (within the muscle cone) Optic nerve glioma Optic nerve meningioma Haemangioma Inflammatory orbital pseudotumour Lymphoma ▸ metastases Arising from the muscle cone Inflammatory orbital pseudotumour Dysthyroid ophthalmopathy Rhabdomyosarcoma (the commonest cause of a paediatric primary orbital mass) Extraconal…

Spinal Dysraphism Spinal Dysraphism Definition This is also known as a neural tube defect (NTD), and are a group of congenital spine abnormalities that may cause progressive neurological damage (affecting 1 : 1000 live births) The common feature is an anomaly of the midline structures of the back It results from incomplete midline closure of the bony and neural spinal tissues following defective primary neural tube closure and…

Cerebellar Malformations Cerebellar Hypoplasia Definition The cerebellum may be small due to a congenital lack of formation or from subsequent atrophy ■ Causes: infection (especially congenital cytomegalovirus) ▸ inborn errors of metabolism (e.g. glycolysation disorder) ■ Other rarer causes: carbohydrate-deficient glycoprotein syndrome ▸ infantile neuroaxonal dystrophy ▸ pontocerebellar hypoplasia ▸ spinocerebellar atrophies ▸ Friedreich's ataxia Clinical presentation Variable hypotonia or ataxia Radiological features MRI Symmetrical atrophy…

Head Injury Subdural Haemorrhage (SDH) Definition Traumatic bleeding between the dura mater and arachnoid mater ▸ it usually arises from rupture of the veins crossing the subdural space (vault fractures are an uncommon cause) ▸ often associated with brain damage These may be extensive – although the haemorrhage is of low pressure, the blood is unrestricted and can spread over the entire brain surface ▪ Acute:…

Intracranial Infection Brain Abscess Definition A focal encapsulated pus-containing cavity ▸ in immunocompetent patients it is usually due to a streptococcal bacterial infection (multiple in 10–50%) ▪ It usually arises by haematogenous dissemination ▸ it can also occur following penetrating trauma or due to direct spread from a contiguous infection ▪ Fungal cerebral abscesses: these typically affect immunocompromised patients ▸ they are similar to a pyogenic…

Cerebral Ischaemia Cerebral Ischaemia Definition Stroke A sudden persistent neurological deficit of vascular origin Causes Large vessel thromboembolic stroke (40%) Most commonly due to thrombus at the site of atherosclerotic plaque or embolization more distally ▸ sites: carotid bifurcation > intracranial internal carotid artery (ICA) > proximal MCA (> anterior cerebral artery (ACA)) ▸ vertebral artery origins > distal vertebral artery (VA) > basilar artery Vasculopathy…