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بسم هللا الرحمن الرحيم Interpretation in·ter·pre·ta·tion DR.Tajuddin Malabarey Associate professor 365-March 2011 Interpretation • Something that serves to explain or clarify: Clarification, Explanation, Illumination, Illustration. • The act or process of explaining the meaning of something. Interpretation Interpretation 1=Normal Radiological Anatomy 2= How to look at the images? (a) Where to look? Systematic approach (b) what look for: (i) abnomal opacty (ii) abnorma radiolucency (iii) distotion or displacement of a normal structure 3= How to interpret the abnormality? (a) Recognizing the abnormality, (b) Describing it in generic terms, (C) Giving a specific diagnosis Normal Radiological Anatomy • Normal radiological image of certain age and sex is a mental image that must be developed How to build up a normal mental image • By developing a systematic approch to examine the radiological image • Advantages: • Minimizes the chance of missing an abnormality • Makes complex images easier to read with practice • Builds up a mental databank of what is normal Normal VS, Abnormal It is not possible to call an image abnormal if the normal appearance is not known!! In order to recognize the abnormal, you first need to know the appearance of the normal. On non-contrast head CT: White Bone is white Calcium is white; Acute hemorrhage is usually white Light Grey Brain parenchyma is light grey; White matter is darker than grey matter Charcoal Grey CSF is very dark grey; Sulci, cisterns and ventricles Black Air is black; Nasal cavity, sinuses, mastoid air cells T1 Characteristics •Dark •CSF •Increased Water – edema, tumor, infarct, inflammation, infection, hemorrhage (hyperacute or chronic) •Low proton density, calcification •Flow Void Johnson,KA and Becker, JA. The Whole Brain Atlas. 1995-1999 •Bright •Fat •Subacute hemorrhage •Melanin •Protein-rich Fluid •Slowly flowing blood •Gadolinium •Laminar necrosis of an infarct •White matter brighter than Gray T2 Characteristics •Dark •Low Proton Density, calcification, fibrous tissue • Paramagnetic substances deoxyhemoglobin, methemoglobin (intracellular), iron, hemosiderin, melanin •Protein-rich fluid •Flow Void •Bright •Increased Water – edema, tumor, infarct, inflammation, infection, subdural collection •Methemoglobin (extracellular) in subacute hemorrhage Johnson,KA and Becker, JA. The Whole Brain Atlas. 1995-1999 •Gray matter brighter than white Interpretation • Learn Normal Radiological Anatomy • How to look at the images? • How to interpret the abnormality? How to look at the images? • Where to look? Systematic approach • What to look for? The documentary evidence of name and age Technical factors Areas of interest (Normal anatomical structures) Patient Name • What to look for? 3.Areas of interest (Normal anatomical structures) Systematic Approach to reading a Head CT I. Check Brain Parenchyma • • • • Check grey/white differentiation Gyri Look for blood Surgeons need to know . . . (size of hematoma, extent of midline shift, herniation) II. Check CSF spaces: Ventricles, Cisterns and Sulci • CSF spaces (ventricles and cisterns) – size, symmetry, midline shift – herniation • Subfalcine – cingulate gyrus crosses falx • Transtentorial – temporal lobe into tentorial notch • Cerebellar – cerebellum into foramen magnum Systematic Approach to reading a Head CT (cont’d 2) III. Check face and skull bones on bone windows – Do not confuse sutures with fracture especially in pediatric patients IV. Check “air spaces” – Sinuses – Nasal airway – Ear Canals and Mastoid air cells What to look for? In CT Head Brain tissue (windows) Pre contrast Post contrast Bone detail (window) Brain tissue RIGHT LEFT Frontal lobe Bone detail Midbrain Pre contrast Cerebellum Post contrast what look for: Normal (i) abnomal opacty (ii) abnorma radiolucency (iii) distotion or displacement of a normal stru distotion or displacement of a normal structure abnorma radiolucency RIGHT LEFT Frontal lobe abnomal opacty Midbrain Cerebellum 3= How to interpret the abnormality? (a) Recognizing the abnormality, (b) Describing it in generic terms, (C) Giving a specific diagnosis Patient’s A Head CT Film findings: BIDMC • R frontoparietal subdural hematoma (6 mm) • Midline marker • R temperoparietal epidural hematoma (1.8 cm) • 6 mm leftward shift of lateral ventricles • Right lateral ventricle • Left lateral ventricle • Effacement of R sulci Epidural Subarachnoid Hemorrhage Subdural Hematoma Parenchymal Hemorrhage Patient B • 57yr old woman • History of migraines • Presents with persistent headache – several months duration – different from her usual headache Need to rule out intracranial abnormality RIGHT LEFT Frontal lobe Midbrain Cerebellum BIDMC PACS system Patient’s B Head CT (no contrast) Film Findings: • Spherical mass • Smooth margined • High attenuation • Slight mass effect • Located just anterior to the Circle of Willis RIGHT LEFT Frontal lobe Midbrain Cerebellum • No acute hemorrhage, edema, infarct BIDMC PACS system RIGHT LEFT Frontal lobe Midbrain Cerebellum DDx: Cerebral mass • • • • • Tumor Hematoma Abscess Arterio-venous malformation (AVM) Aneurysm Patient’s B Head CT (with contrast) RIGHT LEFT Frontal lobe RIGHT LEFT Frontal lobe cerebellum cerebellum BIDMC PACS system 2 brightly enhancing round lesions suggestive of cerebral aneurysms BIDMC PACS system Lets review the anatomy of the Circle of Willis • Communicating system of vessels that supplies blood to the brain • Anterior portion fed by the internal carotid arteries • Posterior portion fed by the vertebral arteries http://www.strokecenter.org/education/ais_vessels/ais048.html Patients B Axial MR (T2 sequence) T2 sequence: CSF is bright (“high signal”) RIGHT LEFT RIGHT BIDMC PACS system BIDMC PACS system Round lesions with flow void confirmed LEFT Menu of tests for evaluating suspected: Cerebral aneurysm • • • • Computed tomography (CT) + contrast Magnetic resonance imaging (MRI) Magnetic resonance angiograpy (MRA) Cerebral angiography MRA - Circle of Willis Our Patient Anatomic Diagram RIGHT LEFT ACA MCA a r l b a s i PCA http://www.strokecenter.org/education/ais_vessels/ais048.html internal carotid internal carotid vertebral arteries BIDMC PACS system Internal carotid artery aneurysms Patient C Patient’s C Normal Patient’s C Normal Patient’s C Interpretation •Features of several diseases, •trauma •and non-trauma CNS Trauma Imaging GROOVE FOR MCA CORONAL SUTURE SELLA TURCICA EXT.AUD MEATUS Normal Epidural H ORBITAL GROOVE Linear fracture Depressed fracture Orbital Fracturesblow-out NORMAL WATERS VIEW Medial/Inferior orbital wall blow-out Orbital Fracturesblow-out NORMAL WATERS VIEW Medial/Inferior orbital wall blow-out Axial CT Coronal CT Orbital Fracturesblow-out Medial/Inferior orbital wall blow-out Depressed right orbital floor Opacification of right maxillary sinus Opacification of right ethmoid sinus “Hanging tear drop”: herniation of orbital fat into maxillary sinus (not seen here) Interpretation Non-trauma Extra-axial vs Intra-axial (external to pia) Meningioma (beneath pia) Glioma Supra-tentorial Glioma vs Infra-tentorial Medulloblastoma Nonenhanced computed tomography scan shows a hyperdense mass resulted in midline shift to the right aspect in the left frontal lobe DSA, Left external carotid artery shows early stain of the mass CECT shows a homogeneous enhancing mass located in the left frontal lobe. DSA: Left external carotid artery shows delayed stain of the mass Hydrocephalus versus Cerebral Atrophy Definition :Hydrocephalus is abnormal accumulation of intracranial fluid resulting from structural or functional block to normal flow of CSF, cerebral atrophy is parenchymal volume loss Hydrocephalus is abnormal accumulation of intracranial fluid resulting from structural or functional block to normal flow of CSF , cerebral atrophy is parenchymal volume loss Agenesis of the corpus callosum Patterns of edema Edema: Increase in tissue water CT - decreased density MR - T1W - decreased signal MR - T2W - increased signal Patterns of edema Vasogenic (intertitial) Cytogenic Normal white matter only neoplasm abscess (intracellular) both gray and white matter infarction White&gray matter Vaogenic oedema (tumor &inflamation) White matter Cytotoxic oedema ( infarction CONCLUSION KNOW YOUR Normal Radiological Anatomy look for: (i) abnormal opacity (ii) abnormal radiolucency (iii) distortion or displacement of a normal structure Interpret the abnormality: (a) Recognizing the abnormality, (b) Describing it in generic terms, (C) Giving a differential diagnosis Give a specific diagnosis KNOW your radiological terminology BEST LUCK HOPE THIS WAS HELPFUL