1	Introduction to Radiology Ian D. McLean DC DACBR Director Clinical Radiology Palmer College of Chiropractic
2	Instructions Do this with a friend. Try and answer the question before clicking through the slides. There are a variable number of clicks for each slide. Just keep going tom you reach the next slide. Feedback is welcome!
3	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
4	What is the basis of patient selection for radiography? History and physical exam findings absolutely critical! never x-ray without this!
5	So what is the secret of image interpretation a well obtained clinical history. a competent clinical examination.
6	What is conventional plain film radiography. An x-ray examination without the use of contrast media.
7	Who discovered x-ray?
8	What are the 5 radiographic densities?
9	Describe mechanisms by which imaging data is recorded X-ray film and radiographic screens with light and x-ray sensitive emulsion Fluoroscopic screens Sodium iodide crystals in radionuclide imaging Electronic sensors – CT
10	Discuss the following radiographic positioning terminology A-P (Anterior-Posterior) PA (Posterior-Anterior) Lateral Oblique Upright vs. recumbent
11	Differentiate anatomical from “chiropractic/surgical” image presentation
12	Describe some methods of stress radiography Spine - cervical and lumbar Acromioclavicular joint Gamekeepers thumb Ankle Knee
13	What is this diagnostic imaging procedure? Fluoroscopy evaluation of motion gastrointestinal musculoskeletal image intensified reduces radiation dose time dependent loss of resolution
14	Describe the basics of Computerized Tomography CT combines x-rays and computers to create cross sectional axial images of the human body.
15	Who invented computerized tomography? 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.
16	Describe the major components of CT 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.
17	Describe the mechanics of computerized tomography to obtain cross-sectional images.
18	Describe the advantages of computerized tomography comparative to routine radiography. Computer enhances soft tissue contrast “Removes” overlaying anatomy May require contrast enhancement CT myelography abdomen evaluation of aneurysm
19	What is a Hounsfield Unit unit of x-ray attenuation passing through tissue CT # Water = 0 Bone +1000 Fat -50
20	What is a Scout Image/Plan Scan? A digital radiograph of the area of examination created by the CT scanner allows correlation with the subsequent axial images
21	How do you recognize that these examinations were obtained with contrast?
22	Describe the primary contrast media used in radiography 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
23	Describe those examinations in which iodine is used 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
24	What is Myelography? contrast media in the subarachnoid space largely replaced by MR and CT
25	What is Arthrography? injection of iodinated contrast media into a joint
26	What is Discography Contrast examination of the disc contents A diagnostic “challenge” (patients says “ouch)
27	What is an 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
28	What is a Barium Contrast Examination 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.
29	What is Radionuclide Imaging 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
30	Describe the attributes of a Bone Scan 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
31	What is SPECT Single Photon Emission Computed Tomography SPECT imaging involves the rotation of a photon detector array around the body to acquire data from multiple angles. Used in Brain Cardiac Bone
32	What are these images? SPECT
33	What is DEXA? Dual Energy X-ray Absorptimetry 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.
34	Describe T Scores 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
35	Describe the relationship between Fracture Risk and T scores 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.
36	What is PET 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
37	Describe the mechanics of PET 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
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39	What is Diagnostic Ultrasound uses high frequency sound waves to image soft tissue structures 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
40	What is this examination?
41	What pathology is this?
42	Briefly describe the basic physics of Magnetic Resonance Imaging A non-ionizing imaging system that uses magnetic fields and radio frequencies to spatially analyzes the magnetic spin properties of tissue nuclei, principally hydrogen.
43	Who are the major players in the development of MRI? 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”
44	Describe the advantages and disadvantages of MRI 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
45	How Large are the Magnetic Fields? The MR magnets are commonly superconductive The magnets range from .2 – 3.0 Tesla (T) The magnetic field of the earth is .5 Gauss (G) 10,000 G = 1T
46	What magnets systems are found in an MRI scanner? Primary magnet Superconducting, permanent, or resistive Gradient magnets Slice selection
47	Why is the Hydrogen Proton central to MR imaging? Is plentiful (in most tissues) Has Charge Has spin Therefore has a magnetic field Behaves as a dipole magnet
48	What happens to the hydrogen proton magnet moments when placed in a high magnetic field? Placing the patient in the magnet creates a net magnetic moment of hydrogen within tissues
49	What else happens to the hydrogen proton magnetic fields? In the presence of a large magnetic field hydrogen protons rotate or precess
50	What is the Lamour equation? 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
51	What do the radiofrequency coils do? They pulse in RF energy to cause the protons to resonate (spin together)……
52	Do you understand what resonance is? Use these illustrations to understand this principle.
53	What happens when RF energy is pulsed into the patients tissue? The pulse is manipulated to tilt the H² magnetic field a set amount. 90^o and 180^o are common.
54	What happens when 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.
55	Describe the four aspects of MRI image generation.
56	Manipulation of the RF pulse, and the time of signal detection result in images of differing contrast. Which image is T1, which is T2? Black CSF T1 White CSF T2
57	Which image is T1, T2?
58	What is TR and TE? Scan Sequences SE = Spin Echo technique TR = repetition time length of time before the next RF pulse is applied TE = echo time Determines how long after the RF pulse the signal is collected
59	What makes a T1 image?
60	What makes a T2 image?
61	Is this image T1 or T2? T1 short TR short TE
62	Is this image T1 or T2? T2 long TR long TE
63	What safety issues can you remember associated with MRI? Ferromagnetic Metal Objects substantial pull/ dangerous speed if let free scissors/paging devices/gas cylinders implanted prosthetic devices (joints, valves, vascular clips, cochlear implants) heart valves are attracted but undergo far greater forces by the contraction of a beating heart surgical clips that have been in situ for years are well anchored by surrounding scar tissue, and even newly inserted sternal sutures are sufficiently immobilized to be safe in the magnet metallic objects in vulnerable positions such as cerebral aneurysm clips and intra-ocular foreign bodies must not be risked unless known to be non ferromagnetic tatoos, cosmetics,dental work can distort the field and lead to image degradation
64	What contrast agent is associated with MRI? 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
65	Which T1 Image is with Gd
66	Which T1 Image is with Gd? A soft tissue mass effect is seen in the lateral recess on the right at L4-5, replacing the normal epidural fat. After Gadolinium administration, marked enhancement is seen in the lateral recess. The differential diagnosis in a post surgical back includes primarily recurrent herniated disk vs. scar. Post surgical scar will usually show enhancement with Gadolinium, unlike recurrent disk. The fat suppression improves the conspicuity of the enhancement.