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Radiology IIan D. McLean DC DACBRDirector Clinical Radiology

Palmer College of Chiropractic

CV

New ZealanderEducation.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 experienceProfessional 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 1989Radiologist – NYDIC Open MRI of AmericaContinuing Education faculty, PCC.Lecture nation wide 6- 8 times per year to state chiropractic associations.Professional Memberships.Member, Iowa Chiropractic SocietyPast President, East Central District, Iowa Chiropractic Society.American Chiropractic Association.American Chiropractic College of RadiologyCouncil on Diagnostic Imaging of the A.C.A.Presidents Club, Palmer College of ChiropracticPublications.Clinical Imaging with Skeletal, Chest and Abdomen Differentials. Dennis M. Marchiori. Elsevier 2004lots of journal articles

Review of syllabus

M, T, Th P202Attendance is not required, but you would be insane not to be hereThree 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

Affectiveattitude

Cognitiveknowledge

Psychomotorskills

Reference Text

Clinical Imaging - With Skeletal, Chest and Abdomen Pattern Differentials

Dennis Marchiori DC, MS, DACBR

Tawnia Adams DCRobert Percuoco DCIan McLean DCTracey LittrellRay Conley

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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 websitemcleanradiology.com

http://www.mcleanradiology.com http://www.mcleanradiology.com

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Questions & Comments:

IMcLeanDC@aol.comIntroduction to Imaging

Question

Radiology is a DIAGNOSTIC PROCEDURE soWhat is the value of diagnosis?

Relates an understanding of patient anatomy andphysiology.Communicates dataDictates management

ChiropracticMedicalBothOther

Palmer Tenets

The Palmer Chiropractic University System maintains that a chiropractic examination incorporates the use of diagnostic procedureswhen indicated, including some or all of the following:

Patient historyExamination 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 clinicianinclude wellness promotion, health assessment, diagnosis and the chiropractic management of the patient's health care needs. Whenindicated, 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 examsIntrinsic part of many chiropractic techniques

MRI “gold standard” for musculoskeletal imaging

Criteria for ordering radiographs (p. 207)

Remains controversial

Medical criteria vs. chiropractic techniqueLack of empirical data

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Question

Which chiropractic patients should be x-rayed?AllSomeNone

Patient Selection Parameters

History and physical exam findingsabsolutely critical!never x-ray without this!

Confirmation of clinical findings

Purpose of Imaging Studies

Assist clinical impression (diagnosis) and managementContribute to clinical pictureEvaluation of :

suspected pathologybiomechanics

scoliosiscomponents of subluxation

Questionable Histories

“rule out pathology”Lacks specificity

Hasn’t been x-rayedNo RDA for x-ray

Find subluxationsLacks 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)

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So what is the secret of image interpretation

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Conventional Plain Film Radiography.

An x-ray examination without the use of contrast media.Shows osseous pathologyShows mal-alignmentPoor sensitivity to early diseaseInexpensive

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% ofelectron beam energy!

Basic X-ray Principles

High-energy short-wave electromagnetic radiationAbility to penetrate various materialsVariable attenuation of the x-ray beamIonizes atoms - removes electrons

p. 24-25

X-ray Imaging

X-Ray SourcePatient

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, thegreater the attenuation andthe less blackening of the film

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X-ray images represent a summation of densities

Terminology

Dense (“white”)opaqueradiopaqueradiodense

Lucent (“black/dark”)radiolucent

Appearance of the radiograph (fig. 5-11)

Water

Fat (oil)

AirBone

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 rayPosition from the image receptor

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Anatomical Distortion.

RadiographicUnequal Magnification

AnatomicExample

Lateral lumbar spine radiography.L5 foraminal stenosis?

Recording Media

X-ray film and radiographic screens with light and x-ray sensitive emulsionFluoroscopic screensSodium iodide crystals in radionuclide imaging Electronic sensors – CT

Positioning Terminology

A-P (Anterior-Posterior)PA (Posterior-Anterior)LateralObliqueUpright vs. recumbent

Image Presentation

Chiropractic/surgical anatomic

Stress Radiography

Spine - cervical and lumbarAcromioclavicular jointGamekeepers thumbAnkleKnee 20

Stress view of ankle

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Digital imaging (p. 61)

Direct capture radiography (DR)Computed radiography (CR)

Fluoroscopy

evaluation of motiongastrointestinalmusculoskeletal

image intensifiedreduces radiation dosetime dependentloss 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 CTRenal exams (intravenous pyelograms)

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Linear Tomography

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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 areabeing imaged. The table

and the gantry are specially synchronized in order to obtain accurate thin slices.

1http://www.colorado.edu/physics/2000/tomography/auto_rib_cage.html

Back Projection

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Advantages

Computer enhances soft tissue contrast“Removes” overlaying anatomyMay require contrastenhancement

CT myelographyabdomenevaluation of aneurysm

CT vs X-ray

Hounsfield Unit (box 2-2)

unit of attenuationCT #

Water = 0Bone +1000Fat -50

-50100

1000

Scout Image/Plan Scan

A digital radiograph of the area of examinationallows correlation with the subsequent axial imageseach slice is collimated to 3-10 mms

body

ce subarachnoidwith nerve roots

psoas

Axial Lumbar CT with Contrast

body

cordce subarachnoid

Axial Cervical CT with Contrast

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Image Recontruction

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Image Recording

Initially, the images appear on a computer screenThe technologist then transfers the information on the monitor to a laser imagerThe 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 contrastHigh Atomic Weight compounds

Barium and iodine

IodineAdministered by intravenous injection or orallyvascular contrasts

may be allergic reactions patients with known allergies should be examined cautiously

myelographic contrastGI contrasts

BariumGI examinations

usually mild to no reactions

Iodine Contrast Examinations

VascularRenalMyelographyreactions very rare esp. with low osmolar agents

hives (urticarial rash) evaluate for renal function if over 50 or renal historyBUN, creatinine

injected through relatively skinny butterfly needles or catheters

Myelography (p.59)

contrast media in the subarachnoid spacelargely replaced by MR and CT

p. 59

Arthrography

injection of iodinated contrast media into a joint

Conventional arthrography CT arthrography

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Discography (p. 60)

Contrast examination of the disc contentsA diagnostic “challenge” (patients says “ouch)

Intravenous pyelogram

more accurately called "IVU," or intravenous urogramcontrast examination of the urinary tractcontrast 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 enemaUpper GI

The regular, or single contrast, barium enemaair contrast barium enema.

Indications

Barium enemacolon cancerdiverticulitispolyps, especially with the air contrast techniqueintussuseption

Upper GIesophogramhiatus herniaulcerstumors

Barium (sulphate) Contrast

Oral or rectal administration…not vascularupper GI series, barium enemas, sometimes CT scansis as inert as a substance can be except for its slightly chalky tasteIf 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

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Radioisotope

decays - emitting gamma radiationtechnetium most commonly utilized

low radiation dosenontoxic

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 spotsevaluates bone pathophysiology and blood supply

metastatic diseaseinfectionPaget’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 TomographyAs in x-ray CT, SPECT imaging involves the rotation of a photon detector array around the body to acquire data from multiple angles.

BrainCardiac Bone

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SPECT Imaging

Spondylolisthesis

DEXA (p. 58)

Dual Energy X-ray AbsorptimetryQualitative method to assess bone densityDEXA uses beams of x-rays at two engery levels to determine bone density

normal

osteopenic

osteoporotic

DEXA

Evaluates osteopororsisLow energy x-rays are passed through the bones to measure the mineral (calcium) content of the bonesA 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 normalsof 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-scoresT -1 or higher = NORMALT -2.5 to -l = OSTEOPENIAT below -2.5 = OSTEOPOROSIST 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 riskT -score = -3 has 8 times the risk.

DEXA Report

T Score

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PET (p. 62)

Positron Emission TomographyBegins 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 structurescommon examinations:

gallbladderaneurysmkidney, liver etc.obstetrics

Physics

Sonic energy 1-10 MHzPiezoelectric effect from transducerNonionizingReflection of the ultrasound beam from interfaces between tissues produces imageOperator dependent especially in orientation of slicesDoes not image gas or bone

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Ultrasonography

AdvantagesNot employ ionizing radiationUsed in any chosen planeLess expensive than CT or MRIPortable

Carotid ultrasound

Fetal face – 3D ultrasoundAbdomen ultrasound

Ultrasound Examinations

Aortic aneurysm Cholelithiasis

a transverse slice showing obvious gender

Baby (Alex) McLean

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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 DamadienJuly 1977 Magnetic Resonance Imaging

Advantages:Does not employ ionizing radiation“true” three dimensional imagingExcellent 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 superconductiveThe 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 magnetSuperconducting, permanent, or resistive

Gradient magnetsSlice selection

High field Open MRI

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Magnetic Field Strength

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Magnetic Field Strength

Hydrogen Proton

Has Charge Has spin

Therefore has a magnetic fieldBehaves 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

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1

In the presence of a large magnetic field hydrogen protons rotate or precess

Bo

1 fig. 2-6

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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 = yBowhere 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 producedThe signal is detected by the scanner.

MRI – phases (fig. 2-9)

Magnetism

Relaxation

Excitation

Resting

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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 T1White CSF T2

T1

TR

Short T1

TE

Short Long

Long

SD

--- T2

30 msec800 msec

TE =TR =

fig. 210

T2

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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 inertDelivered intravenouslyIncreased signal intensity within pathological tissue on T1 imagesDoesn’t cross the intact Blood Brain Barrier

Shows breakdown of BBBEnhances tumorsEnhances scar tissue

Gdw/oGd

T1 Images with Gd

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T1 Sagittal T2 Sagittal

Axials