Radiology modalities
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Radiology Modalities - PowerPoint PPT Presentation

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Radiology Modalities. Jeff Binder R.T. (R). Plain film. Strengths. Weaknesses. Readily available Low cost Well known uses Best line pair performance . False negatives (fx) Ionizing radiation Poor resolution Poor soft tissue visualization Poor spacial localization

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Radiology modalities l.jpg

Radiology Modalities

Jeff Binder R.T. (R)

Plain film l.jpg
Plain film



  • Readily available

  • Low cost

  • Well known uses

  • Best line pair performance

  • False negatives (fx)

  • Ionizing radiation

  • Poor resolution

  • Poor soft tissue visualization

  • Poor spacial localization

  • C1/c2, c6/c7 hard to visualize

Attenuating technology

Proper uses l.jpg
Proper uses

Rule out advanced imaging

Introductory study

Evaluates IVF well

Not good for central canal stenosis

Tomography l.jpg

Xray images taken in “sections” (slices)

Blurs areas that are not of interest

Similar strengths and weaknesses as plain film

Attenuating technology

Myelography l.jpg

Xray images taken of spinal cord after radiopaque contrast is injected

When used with CT it is the best tool to visualize central canal stenosis

Dr. looks for displacement of contrast on xray

Attenuating technology

Complications l.jpg

Headache (most common)


Arterial bleeding


First contrast used was air

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Bone Scan

Technetium 99 radio isotope used

Emission technology (from the patient)

“hot spots” on scan are osteoblastic activity

SPECT: Single Photon Emission Computerized Tomography

Phosphate used as carrier molecule

PET: Positron Emission Tomography

Glucose used as carrier molecule

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Computerized Tomography

Attenuating technology

Computer generated pictures

Hounsfield Units

Pixels and voxels

Volume averaging used

Slice thickness scout films used

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  • Widely available

  • Improved soft tissue visualization

  • 3d imaging

  • Accurately measure a variety of structures

  • Image manipulation possible (bone and soft tissue windowing)

  • May be combined with myelogram for canal stenosis exam

  • Ionizing radiation

  • Higher cost

  • Intracranial artifacts

  • Artifacts secondary to metallic implants

  • Radiation dose

Ultrasound l.jpg

Sound waves used to form images

No radiation

Readily accessible

Lower cost

Interact with patient

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Magnetic Resonance Imaging

  • Emission technology (from the patient)

  • Hydrogen molecules used for emission

  • Cortex of bone=black

    • Due to lack of hydrogen (water molecules)

  • Evaluates Physiology

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Spinal fracture

Soft tissue injury

Skeletal survey for metastasis

Post traumatic complications

Peripheral entrapment

Central canal stenosis

Intracranial abnormalities

Vascular imaging (MRA first choice)

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  • Magnet (field) strength depicts image quality

    • 1.5 tesla magnetic minimum

    • Larger the magnet= better image quality

  • RF coils are placed on or near the patient to excite the tissue

  • Larmor equation

    • Frequency of procession= gyro magnetic ratio x strength of field

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Relaxation Times

White= high signal, Many H+ emitting signal

Black= low signal, No H+ emitting signal

Tr= Repetition time

Te= echo time

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Tr= 200-600ms

Te= 25ms

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Tr= ~1500+ ms

Te= 50+ ms

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  • BOLD: Blood Oxygen Level Dependant

  • Physiology presented

    • Cortical activation

    • Retinotopic organization of the visual cortex

    • Cerebral basis for language

    • Mapping of the motor cortex

    • Memory

    • Studying psychiatric disorders

  • Advantages over PET

    • No ionizing radiation, less expensive, widely available, studies can be frequently repeated

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Fake functional

Computer tricks to make a study look like a motion study.

Really a series of static images