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What is one of the main indications for Magnetic Resonance Angiography (MRA)?

  • Therapy for vascular malformations
  • Treatment of transient ischemic attacks
  • Study of aneurysms (correct)
  • Evaluation of renal function

    • Which technique in Magnetic Resonance Angiography utilizes radiofrequency pulses to saturate stationary tissue?

  • Phase contrast (PC)
  • Time of flight (TOF) (correct)
  • Maximum intensity projection
  • Contrast-enhanced MRA

    • Which of the following statements about Maximum Intensity Projection (MIP) is true?

  • It is a technique used in computed tomography angiography. (correct)
  • It is utilized primarily for venous disease evaluation.
  • It relies on the use of ionizing radiation.
  • It is a type of contrast-enhanced MRA.

    • What is a primary contraindication for Computed Tomography Angiography (CTA)?

    <p>Severe iodinated contrast allergy</p> Signup and view all the answers

    Which of the following methods allows for the quantification of blood flow velocity in Magnetic Resonance Angiography?

    <p>Phase contrast (PC)</p> Signup and view all the answers

    What is the primary method used in plain radiography to produce images?

    <p>Absorption of X-rays</p> Signup and view all the answers

    Which of the following best describes a contraindication for using plain radiography?

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

    In computed tomography (CT), how are images created?

    <p>By measuring the attenuation coefficients of X-rays</p> Signup and view all the answers

    What enhances soft-tissue details in CT imaging?

    <p>Iodinated contrast material</p> Signup and view all the answers

    What is a distinct advantage of helical CT over conventional CT scanning?

    <p>It can capture multiple images in a single rotation</p> Signup and view all the answers

    Which of the following is NOT an indication for using CT imaging?

    <p>Teenage sports injuries</p> Signup and view all the answers

    What is the significance of the HU value in CT imaging?

    <p>It indicates tissue absorption of X-rays</p> Signup and view all the answers

    What type of tissues appears brightest on a CT scan?

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

    What does T1 relaxation time primarily describe?

    <p>The speed of longitudinal magnetization recovery</p> Signup and view all the answers

    Which imaging technique is primarily better for demonstrating normal anatomy?

    <p>T1-weighted imaging</p> Signup and view all the answers

    In T2-weighted images, which of the following tissues appears hyperintense?

    <p>Vitreous body</p> Signup and view all the answers

    What is the main effect of Gadolinium as an MRI contrast medium?

    <p>It increases the local magnetic field and signal intensity</p> Signup and view all the answers

    Which of the following accurately characterizes the T2 relaxation process?

    <p>It involves the vanishing of transversal magnetization</p> Signup and view all the answers

    Which statement correctly describes the TR and TE parameter requirements for T1-weighted imaging?

    <p>It requires short TR and short TE</p> Signup and view all the answers

    What characterizes proton weighted imaging?

    <p>Long TR with short TE</p> Signup and view all the answers

    Which of the following is a potential risk associated with the use of Gadolinium in MRI?

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

    What feature makes diffusion-weighted imaging (DWI) ideal for detecting recent infarctions?

    <p>It is sensitive to recent alterations in vascular perfusion.</p> Signup and view all the answers

    Which of the following is NOT a contraindication for MRI?

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

    What complication is NOT associated with catheter angiography?

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

    Which imaging technique involves injecting contrast material into a peripheral vein?

    <p>Computed tomography angiography (CTA)</p> Signup and view all the answers

    Which condition would most likely NOT be evaluated using MRI?

    <p>Acute hemorrhagic stroke</p> Signup and view all the answers

    What is a common reason for choosing digital subtraction angiography (DSA) over other imaging techniques?

    <p>It allows for real-time evaluation and therapy.</p> Signup and view all the answers

    What type of imaging involves the use of high-speed spiral CT scanning to capture detailed vascular images?

    <p>Computed tomography angiography (CTA)</p> Signup and view all the answers

    Which of the following conditions is most likely to prompt an MRI examination?

    <p>Thyroid-associated orbitopathy</p> Signup and view all the answers

    What is the primary advantage of using MRI over CT for imaging studies?

    <p>MRI provides superior visualization of soft tissues and visual pathways.</p> Signup and view all the answers

    In which scenario would a CT scan be preferred over an MRI?

    <p>In cases of suspected trauma or acute hemorrhage.</p> Signup and view all the answers

    What should be verified when reviewing imaging studies?

    <p>The scan quality, orientation, and thickness.</p> Signup and view all the answers

    If imaging studies show no abnormality, what should a clinician do next?

    <p>Reexamine the clinical findings and the imaging study correlatively.</p> Signup and view all the answers

    What is essential when imaging of the orbit and head is performed?

    <p>Both coronal and axial sections are necessary for a thorough evaluation.</p> Signup and view all the answers

    Which imaging modality is particularly indicated for vascular disease evaluation?

    <p>MRA, CTA, and CA.</p> Signup and view all the answers

    What is a key consideration when selecting a scan for imaging studies?

    <p>Contraindications for MRI and previous imaging results.</p> Signup and view all the answers

    What should be done if the imaging findings do not match clinical findings?

    <p>Reexamine the clinical findings and the imaging study.</p> Signup and view all the answers

    Study Notes

    Neuroimaging in Neuro-Ophthalmic Disease

    • Plain Radiography uses X-rays to create 2-dimensional images of the body by measuring how much radiation is absorbed by different tissues.
      • Contraindication: Pregnancy
    • Computed Tomography (CT Scan) uses X-rays to create cross-sectional images of the body.
      • Different tissue densities have different attenuation coefficients, which are measured and used to reconstruct the image.
      • Darker areas on the CT scan represent less dense tissues (e.g., air).
      • Brighter areas on the CT scan represent denser tissues (e.g., bone).
      • Contrast material (iodinated) can be used to enhance the visibility of soft tissues.
      • Helical CT uses a continuous rotating X-ray source and detector to obtain a 3-dimensional data set.
      • Multidetector CT (MDCT) uses multiple detectors to acquire data more quickly.
      • Indications for CT:
        • Complex fractures
        • Foreign body localization
        • Orbital lesions (e.g., hamartomas, choroidal osteoma)
        • Lesions causing bone loss or calcification
        • Acute hemorrhagic lesions (e.g., subarachnoid or intraparenchymal hemorrhage)
        • Thyroid eye disease (especially before orbital surgery)
        • Patients with MRI contraindications (e.g., claustrophobia)
      • Risk: Ionizing radiation
    • Magnetic Resonance Imaging (MRI) uses magnetic fields and radio waves to create detailed images of the body.
      • T1 Relaxation (spin-lattice relaxation) describes how quickly longitudinal magnetization recovers.
      • T2 Relaxation (spin-spin relaxation) describes how quickly transversal magnetization vanishes.
      • T1-weighted images (T1WI) demonstrate differences in T1 relaxation times of tissues.
      • T2-weighted images (T2WI) demonstrate differences in T2 relaxation times of tissues.
      • T1:
        • Cerebrospinal fluid (CSF) and vitreous humor are hypointense (dark).
        • Gray matter is relatively hypointense compared to white matter.
      • T2:
        • CSF and vitreous humor are hyperintense (bright).
        • Gray matter is relatively hyperintense compared to white matter.
      • Imaging Terms:
        • TR (Repetition Time): The time between successive radiofrequency (RF) pulses.
        • TE (Echo Time): The time interval between the beginning of transverse relaxation and when the magnetization is measured to produce image contrast.
        • T1 Weighted: Short TR/TE
        • T2 Weighted: Long TR/TE
        • Proton Weighted: Long TR with short TE (signal related to proton density)
      • Gadolinium is a paramagnetic substance used as an MR contrast medium:
        • It enhances local magnetic field and increases signal intensity, making it useful for identifying recent infarctions.
        • Contraindications:
          • May cause nephrogenic systemic fibrosis.
          • Contraindicated in patients with a history of previous gadolinium allergy.
      • Indications for MRI:
        • Optic disc edema or pallor
        • Optic neuritis
        • Orbital mass, thyroid-associated orbitopathy, orbital injury, orbital inflammation, asymmetry, exophthalmos, enophthalmos
        • Vision loss (optic nerve, pre-chiasm, chiasm, or post-chiasm symptoms).
        • Diplopia disorders of neural origin or ophthalmoplegia
        • Third, fourth, sixth nerve palsy or cavernous sinus syndrome
        • Nystagmus
        • Facial or lid disorders with neural origin (e.g., brainstem)
        • Acquired Horner's syndrome
        • Headache or eye pain of neuro-ophthalmic causes
      • Contraindications for MRI:
        • Incompatible medical implants/foreign bodies:
          • Cardiac pacemakers
          • Metallic prosthetic devices
          • Intracranial metal vascular clips
          • Old cardiac valve prosthesis
          • Cochlear implants or neuro-stimulators
        • Metallic objects on patients (e.g., necklaces, rings, watches, eye makeup)
        • Pregnancy
    • Intracranial Vascular Imaging:
      • Catheter Angiography (DSA) is an invasive procedure that uses X-rays and iodinated contrast material to visualize blood vessels.
        • Provides details about the anatomy and function of the blood vessels.
        • Can be used for diagnosis and treatment (e.g., stenting).
        • Complications:
          • Contrast media reactions
          • Hematoma at puncture site
          • Vasospasm
          • Emboli leading to ischemia
    • Computed Tomography Angiography (CTA):
      • Uses X-rays and iodinated contrast material injected intravenously to obtain detailed images of blood vessels.
      • Advantages:
        • Noninvasive
        • Faster than traditional angiography
        • Provides 3-dimensional images
      • Contraindications:
        • Pregnancy
        • Severe iodinated contrast allergy
    • Magnetic Resonance Angiography (MRA):
      • Noninvasive and does not use ionizing radiation or contrast material.
      • Types of MRA Techniques:
        • Time of Flight (TOF):
          • Fresh inflowing blood produces a high initial magnetization signal.
        • Phase Contrast (PC):
          • Uses magnetic gradients to induce phase shifts in flowing blood, allowing for flow velocity and rate quantification.
        • Contrast-enhanced MRA:
          • Involves intravenous injection of gadolinium-based contrast medium.
      • Indications:
        • Evaluation of aneurysms, vascular malformations, dissection, stenosis, occlusion
        • Transient ischemic attacks
        • Amaurosis fugax
        • Completed strokes
    • Magnetic Resonance Venography (MRV):
      • Noninvasive, uses MRI to visualize veins.
      • Indications:
        • Patients with venous diseases (e.g., deep vein thrombosis)
    • Choosing the Right Imaging:
      • In general, MRI is preferred for visualizing soft tissues and visual pathways.
      • CT is indicated for trauma, acute hemorrhage, fractures, or calcifications within a mass lesion and MRI contraindications.
      • For suspected vascular disease, consider MRA, CTA, and CA (catheter angiography).
      • Orbital imaging is often necessary in addition to brain imaging studies.
    • Reviewing Imaging Studies:
      • Verify patient, date, and study requested.
      • Assess scan quality, orientation, and scan thickness.
      • Identify normal reference structures and abnormal findings.
      • Make a differential diagnosis based on scan results and correlate with clinical findings.
      • Re-examine the clinical findings and imaging study if the findings do not match.
      • Recognize that the lack of an imaging abnormality does not exclude pathology.

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