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Radiology I

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  • 1. 1 Radiology I Ian D. McLean DC DACBR Director Clinical Radiology Palmer College of Chiropractic CV New Zealander Education. Doctor of Chiropractic (D.C.), Palmer College of Chiropractic, Davenport, Iowa, 1979. Residency in Radiology, Cleveland College of Chiropractic, Kansas City, Missouri, 1981 - 1983. Certified as Diplomate American Chiropractic Board of Radiology, (D.A.C.B.R.) 1984. 12 years MRI education and experience Professional Experience. Professor, Department of Radiology, Palmer College of Chiropractic, May 1983 to present. Director Clinical Radiology, Palmer College of Chiropractic Public Clinics. Private Practice of Radiology (1983-) Mississippi Regional Imaging 1989 Radiologist – NYDIC Open MRI of America Continuing Education faculty, PCC. Lecture nation wide 6- 8 times per year to state chiropractic associations. Professional Memberships. Member, Iowa Chiropractic Society Past President, East Central District, Iowa Chiropractic Society. American Chiropractic Association. American Chiropractic College of Radiology Council on Diagnostic Imaging of the A.C.A. Presidents Club, Palmer College of Chiropractic Publications. Clinical Imaging with Skeletal, Chest and Abdomen Differentials. Dennis M. Marchiori. Elsevier 2004 lots of journal articles Review of syllabus M, T, Th P202 Attendance is not required, but you would be insane not to be here Three unit examination Each examination has 40 questions and is equally weighted to calculate the final course grade for 120 points Make-up examinations are scheduled (see syllabus), should be requested prior to regular examination, and reserved for emergencies Additionally, approximately three opportunities for an extra credit point is available through class participation exercises. This will be applied to reading and response exercises in class BE HERE! Competencies Affective attitude Cognitive knowledge Psychomotor skills Reference Text Clinical Imaging - With Skeletal, Chest and Abdomen Pattern Differentials Dennis Marchiori DC, MS, DACBR Tawnia Adams DC Robert Percuoco DC Ian McLean DC Tracey Littrell Ray Conley 0
  • 2. 2 What do I need to know (for the test). This is a clinically based series of presentations that is designed to enhance your knowledge for clinical practice. I am not in the habit of teaching for tests. This information will be literature based, emphasized with 20 years of practice and professional experiences. You will be expected to read the text emphasizing the information the items in class. The notes are given as a study guide. DO NOT RELY ON THEM AS THE SOLE SOURCE OF INFORMATION Palmer’s Radiology Curriculum Radiology I (intro, variants, arthritis, miscellaneous) Radiology II (tumors and trauma) Radiology III (plain film physics) Radiology IV (radiographic positioning) Radiology “V” (chest and abdomen) Clinic film review sessions (image interpretation and clinical correlation) Radiology I Course Plan Unit One: Imaging modalities (chapter 2) Normal anatomy (chapter 6) Image interpretation (chapter 5) Roentgenometrics (chapter 4) Normal variants (chapter 7) Unit Two: Arthritides (chapter 9) Unit Three: Congenital diseases (chapter 8) Infection (chapter 12) Hematologic bone disease (chapter 11) Endocrine, Metabolic, and Nutritional diseases (chapter 14) Imaging Experiences Film review 9:30 am, 12:00 pm, 3:00 pm Radiology grand rounds last Wed each month 2:00 pm McLean Radiology website mcleanradiology.com http://www.mcleanradiology.com http://www.mcleanradiology.com
  • 3. 3 Questions & Comments: IMcLeanDC@aol.com Introduction to Imaging Question Radiology is a DIAGNOSTIC PROCEDURE so What is the value of diagnosis? Relates an understanding of patient anatomy and physiology. Communicates data Dictates management Chiropractic Medical Both Other Palmer Tenets The Palmer Chiropractic University System maintains that a chiropractic examination incorporates the use of diagnostic procedures when indicated, including some or all of the following: Patient history Examination for subluxation complex Biomechanical functional assessment Spinal examination Physical examination Laboratory and imaging studies "As a gatekeeper for direct access to the health delivery system, the doctor of chiropractic's responsibilities as a primary care clinician include wellness promotion, health assessment, diagnosis and the chiropractic management of the patient's health care needs. When indicated, the doctor of chiropractic consults with, co-manages or refers to other health care providers." Imaging and Chiropractic practice (p. 205) Plain film (dominant imaging study) Relatively inexpensive, readily available (> 80% of chiropractors) Substantial tract of the curriculum, NBCE exams Intrinsic part of many chiropractic techniques MRI “gold standard” for musculoskeletal imaging Criteria for ordering radiographs (p. 207) Remains controversial Medical criteria vs. chiropractic technique Lack of empirical data
  • 4. 4 Question Which chiropractic patients should be x-rayed? All Some None Patient Selection Parameters History and physical exam findings absolutely critical! never x-ray without this! Confirmation of clinical findings Purpose of Imaging Studies Assist clinical impression (diagnosis) and management Contribute to clinical picture Evaluation of : suspected pathology biomechanics scoliosis components of subluxation Questionable Histories “rule out pathology” Lacks specificity Hasn’t been x-rayed No RDA for x-ray Find subluxations Lacks anatomical and physiological specificity Does defensive radiography work? Actually no because…… The image needs interpreting (requires knowledge) Relatively insensitive to early disease (there are no “rule out pathology” diagnostic imaging studies) Correlation with clinical symptoms is poor (that osteophyte doesn’t cause pain) 4 4 So what is the secret of image interpretation clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical history clinical 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  • 5. 5 Conventional Plain Film Radiography. An x-ray examination without the use of contrast media. Shows osseous pathology Shows mal-alignment Poor sensitivity to early disease Inexpensive Wilhelm Roentgen 1895 Mrs. Roentgens hand High energy electron beam striking high- Z material produces heat and x-rays. Electron Beam High-Z Material X Rays Less than 1% of electron beam energy! Basic X-ray Principles High-energy short-wave electromagnetic radiation Ability to penetrate various materials Variable attenuation of the x-ray beam Ionizes atoms - removes electrons p. 24-25 X-ray Imaging X-Ray Source Patient Detector An image is produced by the attenuation of the x-ray beam. Attenuation is influenced by the atomic number of the structure. The denser the structure, the greater the attenuation and the less blackening of the film
  • 6. 6 X-ray images represent a summation of densities Terminology Dense (“white”) opaque radiopaque radiodense Lucent (“black/dark”) radiolucent Appearance of the radiograph (fig. 5-11) Water Fat (oil) Air Bone Metal Radiographic imaging is a two dimensional representation of a three dimensional structure. Examinations require at least two views at 90 degrees each other. Magnification. A phenomenon related to the divergence of the x- ray beam from the x-ray tube X-Ray Source Patient Detector I0 I Radiographic Distortion. Unequal Magnification secondary to: Position from the central ray Position from the image receptor
  • 7. 7 Anatomical Distortion. Radiographic Unequal Magnification Anatomic Example Lateral lumbar spine radiography. L5 foraminal stenosis? Recording Media X-ray film and radiographic screens with light and x-ray sensitive emulsion Fluoroscopic screens Sodium iodide crystals in radionuclide imaging Electronic sensors – CT Positioning Terminology A-P (Anterior-Posterior) PA (Posterior-Anterior) Lateral Oblique Upright vs. recumbent Image Presentation Chiropractic/surgical anatomic Stress Radiography Spine - cervical and lumbar Acromioclavicular joint Gamekeepers thumb Ankle Knee 20 Stress view of ankle
  • 8. 8 Digital imaging (p. 61) Direct capture radiography (DR) Computed radiography (CR) Fluoroscopy evaluation of motion gastrointestinal musculoskeletal image intensified reduces radiation dose time dependent loss of resolution Early Fluoroscopy Experience Linear Tomography Blurs anatomy above and below the object plane (fulcrum) to give the appearance of an image slice. Replaced by CT Renal exams (intravenous pyelograms) 1 1 Linear Tomography
  • 9. 9 Linear Tomography Computerized Tomography (p. 50) CT combines x-rays and computers to create cross sectional axial images of the human body. Godfrey Hounsfield 1919–, British electrical engineer. A radar expert for the Royal Air Force during World War II, in the 1950s Hounsfield began developing computer and X-ray technology for EMI, Ltd., an international electronics and entertainment corporation. He built the prototype for the first CT machine, which produced detailed images of cross-sections of the human body, in 1972. For this innovation he shared the 1979 Nobel Prize in Physiology or Medicine with Allan Cormack, who had independently derived and published the mathematical basis of CAT scanning in 1963–64. Hounsfield was knighted in 1981. Computerized Tomography A gantry houses the x-ray tube and detector system. In order to obtain certain angles, the gantry itself can be tilted. A table moves the patient in and out of the gantry in order to position the area being imaged. The table and the gantry are specially synchronized in order to obtain accurate thin slices. 1 http://www.colorado.edu/physics/2000/tomography/auto_rib_cage.html Back Projection
  • 10. 10 Advantages Computer enhances soft tissue contrast “Removes” overlaying anatomy May require contrast enhancement CT myelography abdomen evaluation of aneurysm CT vs X-ray Hounsfield Unit (box 2-2) unit of attenuation CT # Water = 0 Bone +1000 Fat -50 -50 100 1000 Scout Image/Plan Scan A digital radiograph of the area of examination allows correlation with the subsequent axial images each slice is collimated to 3-10 mms body ce subarachnoid with nerve roots psoas Axial Lumbar CT with Contrast body cord ce subarachnoid Axial Cervical CT with Contrast
  • 11. 11 Image Recontruction 1 Image Recording Initially, the images appear on a computer screen The technologist then transfers the information on the monitor to a laser imager The laser imager produces a hard copy x-ray sheet that can be viewed by the radiologist Contrast Media in Radiography (p.54) Used to enhance tissue contrast High Atomic Weight compounds Barium and iodine Iodine Administered by intravenous injection or orally vascular contrasts may be allergic reactions patients with known allergies should be examined cautiously myelographic contrast GI contrasts Barium GI examinations usually mild to no reactions Iodine Contrast Examinations Vascular Renal Myelography reactions very rare esp. with low osmolar agents hives (urticarial rash) evaluate for renal function if over 50 or renal history BUN, creatinine injected through relatively skinny butterfly needles or catheters Myelography (p.59) contrast media in the subarachnoid space largely replaced by MR and CT p. 59 Arthrography injection of iodinated contrast media into a joint Conventional arthrography CT arthrography
  • 12. 12 Discography (p. 60) Contrast examination of the disc contents A diagnostic “challenge” (patients says “ouch) Intravenous pyelogram more accurately called "IVU," or intravenous urogram contrast examination of the urinary tract contrast material injected into the antecubital vein. contrast excreted through the kidneys resulting in excellent pictures of the various components of the kidneys, ureters, and bladder Barium Contrast Examinations a fluoroscopic test used to study the large bowel, or colon. two basic types: Barium enema Upper GI The regular, or single contrast, barium enema air contrast barium enema. Indications Barium enema colon cancer diverticulitis polyps, especially with the air contrast technique intussuseption Upper GI esophogram hiatus hernia ulcers tumors Barium (sulphate) Contrast Oral or rectal administration…not vascular upper GI series, barium enemas, sometimes CT scans is as inert as a substance can be except for its slightly chalky taste If perforation is suspected a water- soluble iodine-based agent is used Radionuclide Imaging (p. 55) A small amount of radioactive material (radionuclide), commonly technetium (Tc) is administered to the body. This substance can be injected, taken orally, or inhaled. Usually “tagged” to other substances to accentuate end-organ uptake
  • 13. 13 Radioisotope decays - emitting gamma radiation technetium most commonly utilized low radiation dose nontoxic very short biological half-life During the exam, images are created by a gamma camera which detects the radiation emitted from the body. Bone Scans Technetium (Tc 99) bound to a phosphate compound (MDP) hot spots evaluates bone pathophysiology and blood supply metastatic disease infection Paget’s disease sensitive but not specific Bone Metastasis Lung Scans perfusion scans (shows blood flow) ventilation scans (movement of air) injected for a perfusion scan and inhaled for the ventilation scan. perfusionventilation SPECT Single Photon Emission Computed Tomography As in x-ray CT, SPECT imaging involves the rotation of a photon detector array around the body to acquire data from multiple angles. Brain Cardiac Bone
  • 14. 14 SPECT Imaging Spondylolisthesis DEXA (p. 58) Dual Energy X-ray Absorptimetry Qualitative method to assess bone density DEXA uses beams of x-rays at two engery levels to determine bone density normal osteopenic osteoporotic DEXA Evaluates osteopororsis Low energy x-rays are passed through the bones to measure the mineral (calcium) content of the bones A bone density measurement will determine the bone mineral density (BMD) for the area measured and compares that result with the average BMD of young adult normals of similar sex and race at their peak BMD. DEXA Scores (box 2-3) Number of standard deviations from young adult normals. The T-score decreases by -1 for ABOUT every 10% of bone lost (ie, a person with 90% of young adult normal bone density will tend to have a T -score of about -1.) World Heath Organization defines osteoporosis on the basis of T-scores T -1 or higher = NORMAL T -2.5 to -l = OSTEOPENIA T below -2.5 = OSTEOPOROSIS T below -2.5 + fragility fracture = SEVERE OSTEOPOROSIS Fracture Risk (box 2-4) The T score predicts fracture risk: For every - 1 SD the fracture risk doubles. T- score = 0 has average risk for a normal 40 year old. T-score = -1 has twice the risk. T-score = -2 has 4 times the risk T -score = -3 has 8 times the risk. DEXA Report T Score 1
  • 15. 15 PET (p. 62) Positron Emission Tomography Begins with an injection of FDG (fluorodeoxyglucose) a molecule of glucose, attached to an atom of radioactive fluor, produced in a cyclotron Positron Emission Tomography The fluor undergoes radioactive decay, emitting a positron the positron collides with an electron, a matter-anti- matter annihilation occurs, liberating a burst of energy, in the form of two beams of gamma rays, in opposite directions detected by the PET scanner fig. 2-31 CT PET Fused Images Ultrasound uses high frequency sound waves to image soft tissue structures common examinations: gallbladder aneurysm kidney, liver etc. obstetrics Physics Sonic energy 1-10 MHz Piezoelectric effect from transducer Nonionizing Reflection of the ultrasound beam from interfaces between tissues produces image Operator dependent especially in orientation of slices Does not image gas or bone
  • 16. 16 Ultrasonography Advantages Not employ ionizing radiation Used in any chosen plane Less expensive than CT or MRI Portable Carotid ultrasound Fetal face – 3D ultrasound Abdomen ultrasound Ultrasound Examinations Aortic aneurysm Cholelithiasis a transverse slice showing obvious gender Baby (Alex) McLean
  • 17. 17 Magnetic Resonance Imaging (p43) A non-ionizing imaging system that uses magnetic fields and radio frequencies to spatially analyzes the magnetic spin properties of tissue nuclei, principally hydrogen. p. 43 History 1946 Felix Bloch proposed that nuclei could behave as small magnets in the presence of a strong magnetic field. 1974 Raymond Damadien - a crude image of a rat tumor. 1977 Damadien produced a body image with the “Indomitable” Raymond Damadien July 1977 Magnetic Resonance Imaging Advantages: Does not employ ionizing radiation “true” three dimensional imaging Excellent soft tissue contrast Disadvantages: Relative high cost (>$1000 per region) Contraindications w/ some implants, artifacts How Large are the Magnetic Fields The MR magnets are commonly superconductive The magnets range from .2 – 1.5 Tesla (T) The magnetic field of the earth is .5 Gauss (G) 10,000 G = 1T MRI – equipment Primary magnet Superconducting, permanent, or resistive Gradient magnets Slice selection High field Open MRI
  • 18. 18 Magnetic Field Strength 1 Magnetic Field Strength Hydrogen Proton Has Charge Has spin Therefore has a magnetic field Behaves as a dipole magnet 1 + - 1 In the MR exam, it is helpful to think of the patient as a group of randomly oriented hydrogen protons Placing the patient in the magnet creates a net magnetic moment of hydrogen within tissues 1 1 In the presence of a large magnetic field hydrogen protons rotate or precess Bo 1 fig. 2-6
  • 19. 19 What is the appropriate RF environment? For protons in tissue, the relationship between the magnetic field strength Bo and the precessional frequency w is given by the Larmor equation w = yBo where gamma is a physical constant (42.58 MHz/T) for the proton the precessional frequency in a 1 Tesla field is 42.58 MHz/T In the presence of a magnetic field and appropriate radiofrequency environment the protons resonate (spin together)…… Bo fig. 2-7 Actually it’s all about resonance! (fig 2-8) A The pulse is manipulated to tilt the H2 magnetic field a set amount. 90o and 180o are common. The RF pulse is removed The H2 magnetic fields realign with the magnetic field. A weak RF signal is produced The signal is detected by the scanner. MRI – phases (fig. 2-9) Magnetism Relaxation Excitation Resting
  • 20. 20 and then a miracle occurs….. computers….algorithms etc…. Manipulation of the RF pulse, and the time of signal detection result in images of differing contrast (table 2-1) T1-weighted, black CSF T2-weighted, white CSF Manipulation of the RF pulse, and the time of signal detection result in images of differing contrast. Black CSF T1 White CSF T2 T1 TR Short T1 TE Short Long Long SD --- T2 30 msec 800 msec TE = TR = fig. 210 T2
  • 21. 21 Spin Density T1 T2 Axials both T1 and T2 are commonly obtained images are in anatomical presentation! R Contraindications (p. 49 Table 2-1) thorough history must be obtained from the patient with particular attention to surgical intervention and industrial exposure to metals. Contrast Agents (p.49) Gadolinium is almost completely inert Delivered intravenously Increased signal intensity within pathological tissue on T1 images Doesn’t cross the intact Blood Brain Barrier Shows breakdown of BBB Enhances tumors Enhances scar tissue Gdw/oGd T1 Images with Gd
  • 22. 22 T1 Sagittal T2 Sagittal Axials