signs_Radiology

Michelangelo Merisi da Caravaggio or Caravaggio (1573(1573)–1610(1610)) Bird-beak sign Bird-beak sign is used to refer to the tapering of the inferior oesophagus in achalasia The same appearance (although it is difficult to see the similarity) is also referred to as the rat-tail sign Bat wing 4th ventricle Bat wing 4th ventricle sign refers to the morphology of the fourth ventricle in the Joubert anomaly and related syndromes The absence of a vermis with apposed cerebellar hemispheres give the fourth ventricle an appearance reminiscent of a bat with its wings outstretched Molar tooth sign The molar tooth sign refers to the appearance of the midbrain in which the elongated superior cerebellar peduncles give the midbrain an appearance reminiscent of a molar or wisdom tooth It was initially described in Joubert syndrome and related disorders (JSRD) 2, but is now recognised to occur in a number of other conditions : renal anomalies, hepatic fibrosis and in syndromes with ocular and digital malformations.  Butterfly glioma • • • • • • • • • A butterfly glioma refers to a high grade astrocytoma, usually a GBM ( WHO grade IV), which crosses the midline via the corpus callosum Other white matter commissures are also occasionally involved The term butterfly refers to the symmetric wing like extensions across the midline.  Most frequently butterfly gliomas occur in the frontal lobes, crossing via the genu of the corpus callosum, however posterior butterflies are also encountered.  Like all high grade gliomas the prognosis is dismal, and usually no attempt at 'curative' resection is made Differential diagnoses primary CNS lymphoma : especially in patients AIDS cerebral toxoplasmosis : especially in patients AIDS tumefactive MS cerebral metastases (rare) occasionally a leptomeningeal process which fills the quadrigeminal and ambient cisterns can cause confusion Honeycombing Honeycombing refers to the computed tomographic (CT) manifestation of diffuse pulmonary fibrosis CT demonstrates clustered cystic air spaces (between 0.3 - 1.0 cm in diameter), which are usually subpleural The walls of the cysts are well-defined and often thick Air-space consolidation in the presence of pulmonary emphysema can mimic this appearance The lyre sign refers to the splaying of the internal and external carotid by a carotid body tumour Classically described on angiography it is also visible on CT angiography he Mercedes-Benz sign describes a star-shaped pattern of gas-fissuring within gallstones initially described on an abdominal radiograph 2 Fissures, usually fluid-filled, are present in close to 50% of gallstones Less than half of these fissured gallstones contain some amount of gas The radiolucency caused by the gas usually appears in a triradiate pattern, mimicking the Mercedes-Benz logo nutmeg liver appearance is due to a perfusion abnormality of the liver usually as result of  hepatic venous congestion When hepatic veins are congested, contrast is prevented from diffusing through the liver in a normal manner This results in a mottled pattern of contrast enhancement in the arterial and early portal venous phase with decreased enhancement of the liver periphery The areas of decreased enhancement are due to decreased portal flow, hepatic congestion and ischaemia On delayed images enhancement of the liver becomes more uniform Hepatic venous congestion may be caused by hepatic veno-occlusive disease, Budd-Chiari syndrome, right heart failure or constrictive pericarditis In Budd-Chiari syndrome the caudate lobe enhances normally as it has a separate draining vein directly into the IVC the Phrygian cap is a variant of normal anatomy and denotes a folding o the fundus of the gallbladder It is of no clinical importance other than to not mistake it for pathology Differential diagnosis gallbladder septae adenomyomatosis (annular variant) Etymology The appearance is reminiscent of a Phrygian cap a head garment worn by inhabitants of Phrygia (modern Turkey) 1200 - 700 BC 1-2 A pine cone bladder or christmas tree bladder is an cystogram appearance in which the bladder is elongated and pointed with thickened trabeculated wall It is typically seen in severe neurogenic bladder with increased sphincter tone (detrusor sphincter dyssynergia) due to suprasacral lesions (above S2-S4) or epiconal lesions (in and around S2-S4) It is however not pathognomonic of a neurogenic bladder and can be seen in patients with lesions anywhere along the sacral reflex arc leading to poor detrusor compliance Occasionally it is also seen in bladder neck obstruction of a non-neurogenic cause The salt and pepper sign is used to refer to a speckled appearance of tissue It is used in many instances, but most commonly on MRI Please note that pathologists also use the term Paraganglioma Used to describe some highly vascular tumours which contain foci of haemorrhage, typically a  paraganglioma The appearance is on on T1 weighted sequences, and is made up of: punctate regions of hyperintensity = salt small flow voids = pepper Typical tumours with this appearance include: paragangliomas glomus tympanicum  glomus jugulotympanicum  glomus jugulare  glomus vagale carotid body tumour pheochromocytoma Sjogren syndrome The parotid gland in Sjogren's syndrome has also been described as having a salt and pepper appearance, due to a combination of punctate regions of calcification (pepper) and fatty replacement (salt) Vertebral haemangioma A less common usage for the term is for vertebral haemangiomas which have a courser black and white dotted appearance especially on axial T2 and T1 images (salt = fat, pepper = coarsened trabeculae) MRI noise artefact A related use of the term is to describe the noise sometimes seen in MRI images.  When you think about it, you can probably find folk who have used the term for all sorts of lesions any lesion that has a fine granular imaging texture will the trick A sunburst appearance is a type of periosteal reaction giving the appearance of a sunburst secondary to an aggresive periosteitis.  It is frequently associated with osteosarcoma but can also occur with other aggressive bony lesions such as an Ewing sarcoma The thumb sign or thumbing of the pons is described in chordomas as is meant to be relatively specific It is seen in midline sagittal projection as a projection of the tumour indenting the pons.  It should not be confused with the clinical "thumb sign" of Marfan's disease, in which the tip of the thumb is visible medial to the little finger when it is clasped in the clenched hand The tram-track sign refers to parallel thickening and enhancement around the optic nerve, and is most frequently seen in the setting of optic nerve meningioma It may however also be seen in 1: orbital pseudotumour perioptic neuritis sarcoidosis leukemia lymphoma metastases perioptic haemorrhage Erdheim-Chester disease It is helpful in distinguishing dural diseases from optic nerve glioma, however it should be noted that in some cases the nerve sheath can be diffusely thickened The tree-in-bud sign describes the CT appearance of multiple areas of centrilobular nodules with a linear branching pattern Although initially described in patients with endobronchial tuberculosis, it is now recognised in a large number of conditions Pathogenesis The tree-in-bud sign occurs as a result of a number of processes, although often they co-exist in the same condition: bronchioles filled with pus or inflammatory exudate e.g pulmonary tuberculosis, aspiration bronchopneumonia bronchiolitis - thickening of bronchiolar walls and bronchovascular bundle e.g cytomegalovirus pneumonitis, obliterative bronchiolitis bronchiectasis with mucus plugging e.g cystic fibrosis tumour emboli to centrilobular arteries (aka carcinomatous endarteritis) e.g breast cancer, stomach cancer etc bronchovascular interstitial infiltration e.g lymphoma, leukaemia 4-5 Radiographic features Tree-in-bud sign is not visible on plain film and is best seen on HRCT Typically they are composed of centrilobular nodules (which are usually 4mm in diameter and peripheral, within 5mm of pleural surface) connected by opacified or thickened branching structres extending proximally (representing the dilated and opacified bronchioles) 1-3.  Aetiology The tree-in-bud appearance represents endobronchial spread of infection Causes include Infective Mycobacterium tuberculosis infection  atypical mycobacterial infections (e.g Mycobacterium avium (MAIC)) viral pneunomia fungal (aspergillus) pneumonia  allergic bronchopulmonary aspergillosis (ABPA) pneumocystis pneumonia Congenital cystic fibrosis immotile cilia syndrome ( including Kartagener syndrome) yellow nail syndrome Connective tissue disorders rheumatoid arthritis (RA) Sjogren syndrome Bronchial obliterative (constrictive) bronchiolitis  diffuse panbronchiolitis Neoplastic bronchioloalveolar cell carcinoma primary pulmonary lymphoma chronic lymphocytic leukaemia A trumpeted internal acoustic meatus is an indirect sign of an acoustic schwannoma and is useful in helping differentiating between one and other cerebellopontine angle entities, especially from a meningioma which typically does not extend The zebra stripe sign occurs where children with osteogenesis imperfecta have been treated with cyclical bisphosphonate therapy, e.g pamidronate When the drug is delivered in cycles, dense bone is formed while treatment is being given This results in dense stripes across the metaphyses of bones which can be visualised radiographically.