BASIC CONCEPTS IN DIAGNOSTIC IMAGING

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BASIC CONCEPTS IN DIAGNOSTIC IMAGING

• J.J. Jimenez, M.D.
• A. Tamrazi PhD
• Carle Clinic Association
• University of Illinois College of Medicine

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Outline

• Introduction
• X-Rays
• Fluoroscopy
• GI
• GU
• CT
• MR
• Innovative Modalities

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Modalities Available in Radiology

• Plain Film / X-Ray/Mammography
• Fluoroscopy
• Ultrasound
• CT
• MRI
• Nuclear Medicine/Molecular Imaging
• Angiography/Interventional

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Relative Cost of Imaging Studies
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Relative Availability of Diagnostic Imaging
Teaching Hospital xxxx xxxx xxxx xxxx xxxx xxxx xxxx
Urban Hospital xxxx xxxx xxxx xxxx xxxx xxxx xxx
Suburban Commun-ity Hosp xxxx xxxx xxxx xxxx xx xxx xx
Rural Hospital xxxx xxxx xxx xxx x xx x
Plain Film Fluoro U/S CT NM MRI Angio-interven-tional
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X-Rays

• Discovered in 1895 and still used today
• Most widely performed imaging exam
• X Rays are emitted and detected in cassette
• Cassette can generate either a film or a digital
  image
• Films are kept on file or in a digital archive

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Most Useful Applications for Plain X-Rays

• Chest
• Musculoskeletal
• Abdomen limited usefulness

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Plain X-RaysPros Cons

• Widely available
• Inexpensive
• Doesnt require advanced technologist knowledge
• Can be performed quickly
• Portable

• Ionizing Radiation
• Relatively insensitive
• Requires patient cooperation

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Fluoroscopy

• Utilizes X-Rays
• Real-time imaging
• Utilizes image intensifier
• Involves use of contrast agents

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Main Uses of Fluoroscopy

• Gastrointestinal Imaging
• Genitourinary Imaging
• Angiography
• Other
• Intraoperative
• Foreign body removal
• Musculoskeletal

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FluoroscopyPros Cons

• Widely Available
• Inexpensive
• Functional and Anatomic
• No sedation required

• Requires ingestion/injection of contrast
• Patient cooperation
• Time consuming

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Gastrointestional Fluoroscopy

• Esophogram/Barium Swallow
• Modified Barium Swallow/Dysphgiagram
• Upper GI
• Small Bowel Series
• Enteroclysis
• Contrast Enema
• Defecography

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Single Contrast vs Double Contrast

• Single Contrast
• Generally uses just thin Barium
• Distends lumen with high density material
• Easier for patient/less mucosal detail
• Double Contrast/Air Contrast
• Thick barium coats lumen
• Effervescent tablets ingested to distend lumen
  with air
• Produces see-through images with greater
  mucosal detail
• Greater sensitivity for small lesions, polyps,
  ulcers

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Single Contrast vs Double Contrast
Single Contrast Barium Enema
Double Contrast Barium Enema
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Contrast Materials for GI Exams

• Barium Sulfate
• Thick used in double contrast studies
• Thin used in single and double contrast exams
• Paste mod Ba swallow and defogography
• Gastrograffin
• Full stregnth rarely used
• Dilute

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Barium vs Gastrograffin
Gastrograffin Swallow Study
Barrium Swallow Study
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Barium Sulfate

• Most widely used
• Better images than gastrograffin
• Chalky taste
• Peritonitis may develop if perforation
• If delayed transit, may form concretions in colon

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Gastrograffin

• Water soluble
• Foul Taste
• Poor mucosal coating
• Basically used for R/O obstruction
• Wont cause peritonitis if perforation
• May cause severe chemical pneumonitis if
  aspirated
• Osmotic pressure draws fluid into bowel lumen
• Progressive distention in small bowel obstruction
• Therapeutic enema in constipation

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Patient Factors in GI Fluoroscopy

• Ability to ingest contrast
• In order to get high quality images, a relatively
  large volume of contrast needs to be ingested
  fairly quickly
• Mobility
• Multiple positions required for GI exams,
  particularly double contrast exams.
• Limited mobility less diagnostic images
• Weight
• Tables have weight limits
• Requires maximal radiographic technique and
  exposure is often suboptimal

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Esophogram or Barium Swallow

• Evaluates pharynx and esophagus
• Limited evaluation of stomach
• Double or Single Contrast
• Mucosal contour and Motility

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Modified Barium Swallow

• AKA Dysphagiagram and at Carle cookie swallow
• Performed with Speech Pathologist
• Barium administered in various bolus
  consistencies ranging from liquid to solid
• Evaluates swallowing mechanism
• Evaluates for aspiration
• Performed on videotape

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Modified Barium Swallow
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Upper GI Exam

• Evaluates esophagus, stomach and duodenum
• Double or Single Contrast
• Can be combined with small bowel series
• Largely replaced by endoscopy and cross-sectional
  imaging
• Fairly insensitive

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Small Bowel Series

• Patient drinks 2 cups of thin Ba
• Overhead films obtained at routine intervals
• The Ba column is followed through until it
  reaches the colon
• Transit time, mucosal contour, bowel loop
  distribution are evaluated.
• Insensitive for small masses

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Small Bowel Series
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Small Bowel Enteroclysis

• Double Contrast Small Bowel Series
• NGT placed at duodenal-jejunal junction
• Ba injected followed by methylcellulose
• See-through appearance to small bowel
• Greater sensitivity for small masses and mucosal
  lesions
• Patient discomfort related to NGT and diarrhea

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Contrast Enemas

• Barium or Gastrograffin
• Double contrast or single contrast
• Generally less sensitive than endoscopy
• Requires bowel prep to assess for mucosal lesions
• Requires some element of patient cooperation

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Contrast Enemas
Single Contrast Barium Enema
Double Contrast Barium Enema
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Defecogram

• Barium paste is inserted into rectum
• Patient is asked to defecate under fluoroscopy
• Ano-rectal and pelvic floor dynamics can be
  assessed
• Rectocele, intussusception, pelvic floor
  relaxation, stress incontinence

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Genitourinary Fluoroscopy

• Cystogram
• Voiding cystourethrogram
• Retrograde urethrogram
• Hysterosalpingogram

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Cystogram

• Usually in adult patients
• Looking for tear or intraluminal mass
• Catheter placed and bladder filled with contrast
  to capacity usually 300-500 ml.
• Spot films obtained when full
• Post void film usually overhead

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Cystogram
Cystogram with Intraperitoneal Rupture
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Voiding CystourethrogramVCUG

• Usually in children with history of UTI
• Searching for vesicoureteral reflux
• In males, evaluate for urethral abnormalities
  posterior urethral valves
• Same as cystogram except when full patient voids
  under fluoro with spot films

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Retrograde UrethrogramRUG

• Male patients
• Pelvic Trauma
• Post-infectious STD- looking for stricture
• Different techniques
• Meatus occluded and contrast injected into
  urethra under fluoro

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Retrograde UrethrogramRUG
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Hysterosalpingogram

• Used to evaluate endometrial canal and fallopian
  tubes
• Infertility and uterine anomalies
• Dye injected into cervical os under fluoro
• Injection continued with goal to opacify the
  fallopian tubes and spill contrast into peritoneum

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Musculoskeletal Fluoroscopy

• Fracture/Dislocation reduction
• Hardware placement in the OR
• Flexion/Extension views of c-spine
• Arthrography
• May be performed in conjunction with MRI or CT

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Techniques Relevant to MSK Radiology

• Radiography (routine and specialized views)
• CT
• MRI
• US
• Densitometry
• Interventional procedures (arthrography,
  percutaneous biopsy/vertebroplasty)

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MSK Radiology
MRISagittal Knee T1 Weighted
Vertebroplasty
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Computed Tomography (CT)

• Cross Sectional imaging modality
• Mobile X-ray tube that rotates around a pt
• Slices of X-ray transmission data reconstructed
  to generate image
• Data displayed in multiple window settings (lungs
  parenchyma, bone, etc.)
• Density measurements/Hounsfield Units analyze
  chemical component of tissue
• HU -150-0 fat, 0 water, 0-20 serous
  fluid, 45-75 blood,
• 100-1000 bone/calcium

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CT Contrast Agents

• Intravenous contrast---iodinated
• Differentiate blood vessels vs. vascular
  internal organs
• Enteric contrast---barium
• Differentiate bowel vs. intra-abdominal
  fluid/masses
• Rectal contrast
• Retrograde urinary bladder contrast

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CT Applications

• Neuro-imaging
• -Acute head trauma, acute intracranial
  hemorrhage
• -Low sensitivity for early ischemic stroke,
  intracranial metastatic disease, white matter
  degenerative disease
• Head and Neck imaging
• -Soft tissue of neck, paranasal sinuses, temporal
  bone imaging, orbital wall imaging

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CT Applications

• Body Imaging
• -Chest, Abdomen, Pelvis (with enteric and IV
  contrast)
• Pulmonary nodules, Renal Calculi (without
  contrast)
• Acute appendicitis (with enteric and IV contrast)
• Specialized protocols
• -Liver masses, pancreatic tissue, renal masses,
  adrenal masses

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CT Applications

• Acute Abdomen
• -decrease rate of false laparotomy procedures
• Trauma Spine Imaging (cervical, thoracic, lumbar)
• Other osseous structures (pelvis, extremities)
• Vascular Imaging
• -CT angiography--- i.e. coronary arteries

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CT Axial, with oral contrast in stomach
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CT
PET
PET/CT
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The Power of CT
CTA (CT Angiography)
CT Cardiac Imaging
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Magnetic Resonance Imaging (MRI)

• Multi-planar scanning
• Without ionizing radiation
• Images generated using powerful magnets and
  pulsed radio waves passing through the body
• Data from Pts body used to generate image
• Field strength of magnets 0.3-3.0 Tesla

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MR Contrast Agents

• Intravenous contrast---Gadolinium chelate-based
  contrast agents
• Gadolinium is a paramagnetic lanthanide that is
  toxic as a free metal
• Contrast to evaluate BBB, intracranial edema and
  hemorrhage
• Novel agents being developed as tagged Monoclonal
  antibodies for Molecular Imaging

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MR Applications

• Neuro-imaging
• -Excellent tool due to high soft tissue contrast
  resolution
• -Abundant water content of CNS allows for
  imaging soft intracranial tissue
• Head and Neck imaging
• -Multi-planar capability allows for monitoring
  extent of disease
• -Differentiating subtle soft tissue boundaries of
  head and neck

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MRI Axial, T2-Weighted
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MR Applications

• Body Imaging
• -Thorax mediastinal, hilar, chest wall
  abnormalities
• Limited lung imaging due to artifacts
• New advances in breast imaging
• Potentials for cardiac MRI with coronary MR
  angiography

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MRI Breast Imaging
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MR Applications

• MSK Imaging
• - High sensitivity for neoplastic, inflammatory,
  and traumatic conditions of bone and soft tissue
• - T1-weighted---fluid collections and
  abnormalities in fatty marrow
• - T2-weighted---lesions in both marrow and soft
  tissue

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MRI Sagittal, T1-Weighted
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Innovative Modalities

• Constantly evolving face of radiology
• New contrast agents for CT and MR
• Molecular Imaging
• - Imaging molecular events---enzymatic activity,
  receptor binding, cellular events
• Interventional Radiology and Interventional
  Neuroradiology