Neuroimaging: Imaging Modalities & Pathologies PDF

Dr. Hind Toufig MD, Radiology Gratitude and respect to professor Essam Abdulbary and Dr. Maram, their original work was used as a baseline to this lecture. 2 Recognize various imaging modalities used in neuroimaging. Basic brain cross sectional anatomy Iden...

Dr. Hind Toufig MD, Radiology Gratitude and respect to professor Essam Abdulbary and Dr. Maram, their original work was used as a baseline to this lecture. 2 Recognize various imaging modalities used in neuroimaging. Basic brain cross sectional anatomy Identify and describe common pathologies Red flag cases 3  Imaging Modalities Computed Magnetic Tomography Resonance Plain X-ray (CT) Imaging (MRI) Ultrasound Cerebral Myelography (transcranial) angiography Isotope Scanning Interventional 4 The most commonly used are MRI and CT. Transcranial US is mainly for infants when fontanel is still open > to avoid ionizing radiation. used for frequent follow up. Cerebral angiography (conventional angio) has been replaced by CT angiography nowadays. b/c it’s invasive and need sedation It is used before interventional procedures e.g. repair of aneurysm (with the same catheter (in femoral artery), make the intervention) Myelography is also invasive and is replaced by MRI. Used in whom MRI is contraindicated. Contrast is injected via lumbar puncture inside the thecal sac. Followed by CT or Xray Isotope scanning is a study of function, used to confirm brain death or degenerative diseases e.g. Alzheimer’s. Interventional will be studied in as separate lecture. For repair of a brain aneurysm Or thrombolysis Or thrombectomy 5 PLAIN X-RAY VIEWS Skull Xray has been replaced with CT. We use occipitofrontal view (X-ray penetrates skull from posterior) to lower exposure to eye PA (occipitofrontal) Skull Lateral (RT. & Lt.) Sinus (Occipitomental or Water’s view) Vertebral AP Lateral column Oblique 6 PA (OCCIPITO-FRONTAL) VIEW OF SKULL 7 Plain skull films may show lytic deposits (multiple myeloma), Fractures line, abnormal calcifications (meningioma, glioma , AVM ,post -infective foci ), pituitary fossa enlargement In Xray we don’t focus on anatomy. “not important” 8 LATERAL VIEW 9  Assess pituitary fossa in this view Enlarged in pituitary macroadenoma. - Lambdoidal suture joins parietal and occipital bones. - Coronal suture joins frontal and parietal bones. You won’t be asked about anatomy in plain films. 10 Fracture: Well defined sharp edge stop at the sutures rarely branches affect any skull bone present at site of trauma Clinical hx of Trauma Vascular marking: Less defined edges cross the sutures tortuous and branching anatomical sites of vessels How to differentiate Fractures 11 from Vascular markings? 12 How to differentiate a fracture line from sutures? Fracture lines are smooth, shapely defined, clinical hx of trauma. They seem darker on Xray. Suture is not as clear and defined as a fracture, zigzag lines, found in anatomical sites of sutures. Join the 2 parietal bones > Sagittal suture Join frontal and parietal > Coronal suture Join the occipital and parietal > Lambdoidal suture 13 OCCIPITO MENTAL VIEW (WATER`S VIEW) 14 Water’s view: position as if drinking water. This view is for paranasal sinus specifically maxillary and has been replaced by CT. You can assess : maxillary sinus. Nasal septum Odontoid process (C2) Frontal sinus #In AP view of spine it is difficult to assess odontoid process. 15 Water’s view of skull. Findings? Right maxillary opacification indicating sinusitis. 16 SINUSITIS (AIR FLUID LEVEL) Air fluid level in the Left maxillary sinus indicating Acute sinusitis. 17  Osteomeatal complex Drainage path for sinuses. Turbinates: When blocked lead to If patient has allergic rhinitis sinusitis they could enlarge and block drainage causing sinusitis Nasal septum 18 CT maxillofacial with Coronal reconstruction. CT has better anatomical + pathological details than Xray CT for paranasal sinus: Pt lie supine in examination table Axial cuts are taken Coronal reconstruction Brain sections are done as well to detect complications. Assessment of sinus: Causes of sinusitis like osteo-meatal complex blockage (drainage for ethmoid + maxillary), deviated septum and hypertrophied turbinate Complications like orbital cellulitis, abscess and meningitis, brain abscess, Venous sinus thrombosis. Abnormalities? Air bubbles and Opacification of Right maxillary sinus. Air fluid level in The left maxillary sinus Both indicating sinusitis. 19 SPINAL RADIOGRAPHS[ AP, LATERAL& OBLIQUE VIEWS] In plain films of spine we assess the following: § Alignment [lordosis, kyphosis, straightening] AP Lateral § Bony texture [ normal, osteoporosis] § Disc spaces [ maintained, narrowed,…] § Others: Fat outlining the psoas muscle o Paravertebral shadows [dorsal spine] o Sacroiliac joints [lumbar spine] e.g. psoriasis Cone view 20 - Plain spinal films are initially utilized in the initial evaluation of trauma - Cone view: for L5-S1 which is a weight bearing disc subjective to disc herniation - As you go down the disc spaces become wider except L5-S1 you accept some narrowing in it because it is weight bearing. The normal spine alignment is: Lumbar lordosis, Thoracic kyphosis, cervical lordosis. Bony texture: In osteoporosis you will have low density Paravertebral shadows - They represent soft tissue e.g. fat - disturbed in cases of tumors and paravertebral abscess (TB of spine). 21  Disc space Vertebral body PEDICLES Transverse process Spinous process LUMBAR SPINE AP, LATERAL & OBLIQUE VIEWS 22 oblique view: Intervertebral foramens, where the nerve roots exit, is assessed in this view. A collar in the Scottish dog neck indicates pars interarticularis fracture. 23 oblique view: Intervertebral foramens, where the nerve roots exit, is assessed in this view. A collar in the Scottish dog neck indicates pars interarticularis fracture. 23 24  Each vertebra joint to the vertebra above and to the vertebra below by Facet joints Each vertebra has superior & inferior facets posteriorly Facet joints & ligaments stabilize spine and maintain alignment. Bone b/w superior & inferior facets is called pars interarticularis à it is the weakest part of the vertebra which might break due to repeated microtrauma (stress fracture). Fracture of pars interarticularis is called spondylolysis If the fracture occurs bilaterally à cause spine instability and risk of the upper spine moving from position anterior or posterior “spondylolisthesis”. Causes/Risk factors: - young adolescent ( grade 1 (mainly) 50% >grade 2 75% > grade 3 100% > grade 4 In the exam you will get grade 1. Doctor’s Note: The normal pars interarticularis is shown by the white arrow. 27 spondylolysis of L4 with grade I spondylolisthesis of L4 over L5 28 Xray lumbosacral spine, Lateral projection, showing Radiolucent line of pars interarticularis indicating Spondylolysis of L4 with grade 1 Spondylolisthesis of L4 over L5. Spondylolisthesis causes: 1. degenerative spondylolisthesis, is the result of degenerative changes (facet arthritis and ligementum flavum weakness) and is common among older females above 40-50 years. 2. Isthmic: defect in pars interarticularis(spondylolysis) 3. Traumatic(fracture of neural arch) 4. dysplastic( congenital abnormalities) 5. pathologic ( malignancy or infection) 6. post surgical 29  Odontoid process Intervertebral foramen Cervical Spine AP, Lateral and Oblique views LPO will demonstrate the right foramina. Cone shaped structure is Odontoid process of C2 30 AP starts from C3. 31 We assess § Fractures § Bone texture § Facet joint > OA § Disc lesions § Spinal cord § infections intervertebral disc § neoplasms Facet joints 3D Sagittal reconstruction reconstruction image image 32 - Cut spine: - Pt lies supine in the examination table - Cuts are taken as axial - And you can order the computer to make a reconstruction image (with different projection) and 3D image - CT can assess facet joints if there’s OA or not and their effect on the spinal cord & exiting roots - You can also assess spinal canal à we measure the space between disc to posterior process if 1.3 cm or greater it is adequate, if less than 1.3 then its stenosed. 33 BONE WINDOW VS SOFT TISSUE WINDOW Skin Subcutanous Fat Spinal muscles Spinal cord 34  CT of cervical spine. Sagittal reconstruction Bone window = you can’t see soft tissue details + bone is not dense Soft tissue window= you see soft tissue details + bone is bright Cortical bone is clearer in CT. 35 MRI Sagittal Plane 36 - MRI is a multiplanner cross-sectional imaging modality, meaning: cuts from the beginning are taken axial, sagittal and coronal - MRI has HIGHER soft tissue resolution. - MRI is excellent in detecting bone marrow lesions & spinal cord lesions. - How to differentiate b/w MRI & CT image of the spine: - In CT, cortical bone appears dens. In MRI, cortical bone is black and bone marrow is clearer - In MRI, you can see the disc details. In CT, you see just the space - In MRI, you can see coda equina - MRI has many sequences, most important are T1 and T2. T1: fluid (CSF) or discs are black/dark (hypointense/ low signal intensity) T2: fluid (CSF) or disc are bright (hyperintense/ high signal intensity) - If disc looses its material (in degenerative disease), it will appear darker. 37  Psoas muscles Spinal cord Exiting foramina Paraspinal muscles MRI, Axial view.T2 38 Black dots in the spinal cord are cauda equina.  FAT Left to right: - MRI of Lumbosacral spine, saggital plane, T1. - CT of lumbosacral spine, saggital reconstructed view, bone window. 39 - CT of cervical spine, saggital reconstructed view, soft tissue window Evaluation of: § Spinal canal § Bone marrow § Fractures § Disc lesions § Spinal cord § Spinal infection § Spinal neoplasms 40  A B C 41 MRI of cervical spine, saggital view, T2. How to know spinal canal is adequate or stenosed? - you need to assess it in T2. difficult in T1 - If adequate amount of CSF anterior and posterior to SC à normal (as pic. A) - Loss in one side (anterior or posterior) à mild degree stenosis (as pic. B) - Lost in both side à severe degree of spinal canal stenosis (as pic. C) Causes: - Disc lesions - Tumor - Hypertrophy of ligamentum flavum 42 Osteophyte Disc hernia 43 Left to right: - Xray: lateral view of lumbar spine: anterior osteophytes, narrow disc space or decreased disc height, sclerosis. (degenerative changes) - CT Myelography: osteophyte, narrow disc space and disc hernia - MRI T2: darker disc which means loss of water content or dehydration (degeneration), disc herniation, loss of disc height, spinal canal stenosis and causa equina compression. (degenerative changes) > b/w L4-L5 and b/w L5-S1 44 C2 45 MRI Cervical spine, Sagittal view, T2WI shows multilevel disc dehydration, disc herniation at C4-C5, C5-C6 levels causing mass effect on the thecal sac and central canal narrowing, no spinal cord signal abnormality - spinal cord signal abnormality = when spinal cord is severely compressed, it becomes edematous and you’ll see whiteness inside the cord itself. This means that the compression is so severe that it causes neurological sx) - Most common Cause of disc hernia? Degenerative spine most commonly in elderly. - Another cause is trauma (Start counting from odontoid (C2)) 46 Cervical spine Sag T2WI shows multilevel disc dehydration, disc herniation at C4-C5, C5-C6 levels causing mass effect on the thecal sac and central canal narrowing , no spinal cord signal abnormality 47  Psoas muscles enlarged and TUBERCULOSIS OF SPINE show abnormal signal (POTT'S DISEASE ) Abscess Abscess Kyphotic deformitiy Lumbar axial view T2 Ring enhancement ney d Ki MRI dorso-lumbo-sacral spine, sagittal plane T2W Lumbar axial image with contrast T1WI (b/c #lumbar is identified on axial view contrast is water soluble > excreted by 48 kidneys à kidneys are white) by presence of kidneys peripherally.  Infection of the vertebrae is called spondylitis Infection of the disc is called discitis. Infection of spine is called spondylodiscitis. Can be caused by bacterial, viral, fungal, parasitic infections. TB OF SPINE: Usually affects thoracic and first lumbar vertebra Usually affect more than 1 vertebra, start at vertebra then disc. Presentation: Constitutional symptoms of long duration (night sweat, fever, loss of weight, anorexia, fever) Patient usually not very toxic as compared to other bacterial infection à that’s why when it causes abscess, it’s called cold abscess of spine. Diagnosis: imaging's are only suggestive. Confirmatory diagnosis is by aspiration & culture How is it detected? - Abnormal signal intensity affecting multiple vertebra with destruction at level of T12 - Anterior and posterior abscess collection giving kyphotic deformity and narrowing of spinal canal and compression of spinal cord - Psoas muscle abnormal signal intensity, enlarged with ring enhancement with uniform thickness on contrast which indicate abscess. - Trauma pt, suspicion of disc herniation à don’t give contrast - Tumor, infection à give contrast NOTE: CONTRAST IS ALWAYS GIVEN IN T1 NOT IN T2 49  1. Abnormal signal intensity on T2W images involving the T11àL2 vertebral bodies and T12/L1 disk à T11/L2 spondylodiscitis. And there is adjacent paravertebral collections, with intense ring enhancement after contrast injection--> 'cold abscesses' of TB 2. A kyphos deformity has occurred secondary to a severe T12/L1 spondylodiscitis, with compression of the spinal cord. 50 51 MRI of Lumbosacral spine, sagittal view, T2WI shows multi-level disc degenration with loss of hieght + anterior displacment of L4 over L5 by about 25% Dx: Spondylolysthesis Grade 1 of L4 over L5 secondary to multilevel disc degenerative changes 52