Medical Imaging Techniques and Applications
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Questions and Answers

CT scan performs multiple cross-sectional X-rays.

True

Denser tissues appear more dark than less dense tissues in a CT scan.

False

Which of the following is true about helical CT imaging compared to conventional CT?

  • It allows rapid scanning for CT angiography. (correct)
  • It has more motion artifacts than conventional.
  • It takes longer to complete than conventional.
  • None of the above.

    • CT is considered before orbital surgery of thyroid eye disease.

    <p>True</p> Signup and view all the answers

    What condition has a higher risk of developing after injection of contrast medium for MRI in patients with chronic kidney disease?

    <p>Nephrogenic systemic fibrosis</p> Signup and view all the answers

    Which test is considered the best electrodiagnostic test for optic neuritis?

    <p>pVEP</p> Signup and view all the answers

    Which is true about MR angiography?

    <p>Used to detect intracranial aneurysm.</p> Signup and view all the answers

    Which of the following is a manifestation of MS in the brain?

    <p>All the above</p> Signup and view all the answers

    Which artery's rupture is associated with an epidural hematoma?

    <p>Middle meningeal artery</p> Signup and view all the answers

    The pupil is always spared in intra-aneurysmal effects that affect CN3.

    <p>False</p> Signup and view all the answers

    What is the best long-term treatment for ocular myasthenia gravis?

    <p>Pyridostigmine</p> Signup and view all the answers

    Which of the following tests is highly sensitive to myasthenia gravis?

    <p>AcHR antibodies test</p> Signup and view all the answers

    Ischemia due to right posterior cerebral artery occlusion results in left homonymous hemianopsia.

    <p>True</p> Signup and view all the answers

    Which of the following will show abnormality in a patient with bacterial meningitis?

    <p>Increased protein levels</p> Signup and view all the answers

    The optic nerve of the left eye is labeled as ______.

    <p>A</p> Signup and view all the answers

    Which of the following shows T1 MRI and T2 MRI?

    <p>Pic A shows T2 MRI and pic B shows T1 MRI</p> Signup and view all the answers

    Which measures the molecular diffusion of water within brain white matter?

    <p>Diffusion tensor imaging</p> Signup and view all the answers

    Doppler Ultrasound is the next step of neuroimaging after CT.

    <p>False</p> Signup and view all the answers

    Which structure controls horizontal gaze?

    <p>All of the above</p> Signup and view all the answers

    Ocular tilt reaction is characterized by skew deviation, ocular torsion, and head tilt.

    <p>True</p> Signup and view all the answers

    Which of the following conditions is characterized by the combination of CPEO and pigmentary retinopathy?

    <p>Kearns - Sayre syndrome</p> Signup and view all the answers

    Study Notes

    CT Scan

    • Multiple cross-sectional X-rays are used.
    • Iodinated contrast material is used.
    • Denser tissues appear darker than less dense tissues.
    • Bone and brain tissues appear dark; water and air appear bright.

    Helical CT Imaging

    • Faster scanning for CT angiography than conventional CT.

    CT Indications

    • Detecting head fractures.
    • Used before orbital surgery in thyroid eye disease.
    • Comparing proptosis between the two eyes.

    Nephrogenic Systemic Fibrosis

    • Patients with chronic kidney disease on hemodialysis have a higher risk of developing nephrogenic systemic fibrosis after contrast injection.

    Optic Nerve

    • The optic nerve of the left eye is identified in a picture, looking as if you are facing the patient.

    MRI

    • T1 MRI:
      • White matter appears bright, gray matter appears dark, ventricles are dark.
    • T2 MRI:
      • White matter appears dark, gray matter appears bright, ventricles are bright.
    • T2 weighted with fat suppression images:
      • Fat tissues appear dark.

    Diffusion Tensor Imaging

    • Measures the molecular diffusion of water within brain white matter.

    Optic Neuritis

    • Symptoms include blurry vision, periorbital pain, and abnormal color vision, often with central scotoma.
    • The pVEP (patterned visual evoked potential) is the best electrodiagnostic test to perform.

    Neuroimaging for Optic Neuritis

    • MRI is the best next step in neuroimaging for optic neuritis.

    Giant Cell Arteritis (GCA)

    • MR angiography is not used to detect intracranial aneurysms.

    Diffusion Weighted Imaging

    • Used to identify recent vascular infarctions.

    CTA

    • Uses ionizing radiation and iodinated contrast material.

    Indications for MR Venography

    • Papilledema
    • Optic Neuritis
    • Thyroid Eye Disease
    • Cranial palsy caused by arterial aneurysm

    Manifestations of Multiple Sclerosis (MS) in the brain

    • Periventricular region
    • Juxtacortical region
    • Corpus callosum

    Epidural Hematoma

    • Results from rupture of the middle meningeal artery.

    Cranial Nerves

    • CN3: Carries fibers to the iris sphincter and ciliary body.
    • Intra aneurysm affecting CN3:
      • Ipsilateral partial palsy.
      • The pupil can be spared.
      • Aberrant regeneration can happen due to the aneurysm.

    Ocular Myasthenia Gravis (OMG)

    • Ptosis is due to weakness of the levator palpebrae muscle.
    • Eyelid retraction does not occur.
    • Pupils are involved.
    • Antibodies cause enlargement of the orbital neuron sheaths.
    • Cogan’s lid twitch sign is present.
    • Treatment:
      • Pyridostigmine is the best long-term treatment.
      • Rituximab, cyclosporine, and steroids can also be used.

    OMG Testing

    • AcHR antibodies test is highly sensitive to myasthenia gravis.

    Graves' Ophthalmopathy

    • Treatment includes:
      • Smoking cessation.
      • Assessment and treatment of systemic thyroid disease.
      • Treatment approach is based on clinical activity, severity, and duration of the disease.

    Oculomotor Nucleus Lesion

    • Can cause:
      • 3rd, 4th, and 6th cranial nerve palsies with monocular vision loss.
      • Orbital apex syndrome.

    4th Cranial Nerve Palsy

    • Symptoms include hypertropia of the right eye greater in left gaze, left head tilt, and excyclotorsion of the right eye.
    • The hypertropia does not change when the patient is in a supine position.

    Skew Deviation vs. 4th CN Palsy

    • The spine-upright test can help differentiate between skew deviation and 4th CN palsy.

    Congenital Right 4th CN Palsy

    • Large vertical fusional amplitude is not present.

    6th Cranial Nerve Palsy

    • Greater esotropia at near than at far.
    • Greater esotropia when looking left.
    • Limitation in right gaze.

    Foville Syndrome

    • Characterized by ipsilateral CN V, VI, and VII.

    Kearns-Sayre Syndrome

    • Characterized by the combination of CPEO (chronic progressive external ophthalmoplegia) and pigmentary retinopathy.

    Duane Syndrome

    • 6-year-old patient presents with limitation in right gaze of the right eye and globe retraction with palpebral fissure narrowing of the right eye on attempted left gaze.

    Horizontal Gaze Structures

    • PPRF (paramedian pontine reticular formation)
    • INC (interstitial nucleus of Cajal)
    • riMLF (rostral interstitial nucleus of the medial longitudinal fasciculus)

    Lesion in the Left MLF (medial longitudinal fasciculus)

    • Causes adduction paresis of the right eye and abducting nystagmus of the left eye.

    Dorsal Midbrain Syndrome

    • Characteristics include:
      • Horizontal gaze limitation.
      • Light near dissociation.
      • Convergence retraction nystagmus.
      • Bilateral lid retraction.

    Ocular Tilt Reaction

    • Includes skew deviation, ocular torsion, and head tilt.

    Electroretinography (ERG) in Macular Dystrophy

    • A depressed a-wave on the ffERG (full-field ERG) indicates a problem in the photoreceptors.
    • A depressed b-wave indicates a problem in the bipolar cells.
    • N95 on pERG (patterned ERG) shows abnormalities in the retinal ganglion cell activities.

    Nystagmus

    • Fusional Maldevelopment Nystagmus Syndrome: Smooth pursuit and OKN asymmetry during monocular viewing.
    • ** Gaze-evoked nystagmus:** Anticonvulsant medications can worsen the condition.

    Peripheral Vestibular Nystagmus

    • Mixed horizontal or vertical waveform jerk nystagmus.
    • Nystagmus subsides within days.
    • Suppressed by visual fixation.

    Defective Vestibular Organ

    • Slow phase towards the opposite side, then a fast phase towards the affected (defective) side.

    Jerk Nystagmus

    • Can have accelerating slow phase and decelerating fast phase.
    • Shows linear velocity.

    Central Retinal Artery Occlusion

    • Patient presents with hypertension and a cherry red spot in the fovea.

    Transient Monocular Vision Loss

    • Evaluate for GCA (giant cell arteritis).
    • Workup includes:
      • Hemoglobin A1c.
      • LDL, HDL, and total cholesterol.
      • ESR and CRP.

    Posterior Cerebral Artery Occlusion

    • Causes left homonymous hemianopsia.

    Migraines

    • Can cause zigzag positive phenomena that expand across a visual field with time.
    • Headaches typically last 4-72 hours.
    • Visual aura lasts for more than 15 minutes.

    Traumatic Brain Injury (TBI)

    • Glasgow Coma Scale (GCS) of 13-15 indicates:
      • Normal MRI.
      • Greater than 30 minutes of loss of consciousness.
      • More than one day of amnesia.
      • More than 24 hours of alteration of mental state.

    Glasgow Coma Scale

    • Scores assess eye opening, verbal skills, and motor skills.

    Bacterial Meningitis

    • Shows abnormalities in the cerebrospinal fluid (CSF) analysis, including:
      • Increased protein levels.
      • Decreased glucose levels.
      • Increased white blood cell count.

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    Description

    This quiz covers essential concepts in medical imaging, focusing on CT and MRI techniques. It includes discussions on helical CT imaging, indications for CT scans, and comparisons of T1 and T2 MRI findings. Understanding these techniques is crucial for accurate diagnostics and treatment planning.

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