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Radiology Modalities

Radiology Modalities. 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 C1/c2, c6/c7 hard to visualize.

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Radiology Modalities

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  1. Radiology Modalities

  2. 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 • C1/c2, c6/c7 hard to visualize Attenuating technology

  3. Proper uses Rule out advanced imaging Introductory study Evaluates IVF well Not good for central canal stenosis

  4. Tomography Xrayimages taken in “sections” (slices) Blurs areas that are not of interest Similar strengths and weaknesses as plain film Attenuating technology

  5. Myelography 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

  6. Complications Headache (most common) Infections Arterial bleeding Arachnoiditis First contrast used was air

  7. 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

  8. Computerized Tomography Attenuating technology Computer generated pictures Hounsfield Units Pixels and voxels Volume averaging used Slice thickness scout films used

  9. Strengths Weaknesses • 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

  10. Ultrasound Sound waves used to form images No radiation Readily accessible Lower cost Interact with patient

  11. 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

  12. Uses Spinal fracture Soft tissue injury Skeletal survey for metastasis Post traumatic complications Peripheral entrapment Central canal stenosis Intracranial abnormalities Vascular imaging (MRA first choice)

  13. 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

  14. Relaxation Times White= high signal, Many H+ emitting signal Black= low signal, No H+ emitting signal Tr= Repetition time Te= echo time

  15. T1 Cortex=black CSF=black Fat=white Tr= 200-600ms Te= 25ms

  16. T2 Cortex=black CSF=white Tr= ~1500+ ms Te= 50+ ms

  17. fMRI • 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

  18. FMRI Fake functional Computer tricks to make a study look like a motion study. Really a series of static images

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