Transcript Concepts in Diagnostic Imaging

BASIC CONCEPTS IN
DIAGNOSTIC IMAGING
J.J. Jimenez, M.D.
A. Tamrazi PhD
Carle Clinic Association
University of Illinois College of
Medicine
Outline
• Introduction
• X-Rays
• Fluoroscopy
– GI
– GU
• CT
• MR
• Innovative Modalities
Modalities Available in
Radiology
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Plain Film / X-Ray/Mammography
Fluoroscopy
Ultrasound
CT
MRI
Nuclear Medicine/Molecular Imaging
Angiography/Interventional
Relative Cost of Imaging Studies
Relative Availability of
Diagnostic Imaging
Teaching
Hospital
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Suburban
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Rural
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Plain
Film
CT
NM
MRI
Angiointerventional
Fluoro
U/S
X-Rays
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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
Most Useful Applications for
Plain X-Rays
• Chest
• Musculoskeletal
• Abdomen: limited usefulness
Plain X-Rays
Pros
Cons
• Widely available
• Inexpensive
• Doesn’t require
advanced technologist
knowledge
• Can be performed
quickly
• Portable
• Ionizing Radiation
• Relatively insensitive
• Requires patient
cooperation
Fluoroscopy
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Utilizes X-Rays
Real-time imaging
Utilizes image intensifier
Involves use of contrast agents
Main Uses of Fluoroscopy
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Gastrointestinal Imaging
Genitourinary Imaging
Angiography
Other
– Intraoperative
– Foreign body removal
– Musculoskeletal
Fluoroscopy
Pros
Cons
• Widely Available
• Inexpensive
• Functional and
Anatomic
• No sedation required
• Requires
ingestion/injection of
contrast
• Patient cooperation
• Time consuming
Gastrointestional Fluoroscopy
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Esophogram/Barium Swallow
Modified Barium Swallow/Dysphgiagram
Upper GI
Small Bowel Series
Enteroclysis
Contrast Enema
Defecography
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
Single Contrast vs Double Contrast
Single Contrast
Barium Enema
Double Contrast
Barium Enema
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
Barium vs Gastrograffin
Barrium Swallow Study
Gastrograffin Swallow Study
Barium Sulfate
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Most widely used
Better images than gastrograffin
‘Chalky taste’
Peritonitis may develop if perforation
If delayed transit, may form concretions in
colon
Gastrograffin
• Water soluble
• Foul Taste
• Poor mucosal coating
– Basically used for R/O obstruction
• Won’t 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
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
Esophogram or Barium Swallow
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Evaluates pharynx and esophagus
Limited evaluation of stomach
Double or Single Contrast
Mucosal contour and Motility
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
Modified Barium Swallow
Upper GI Exam
• Evaluates esophagus, stomach and
duodenum
• Double or Single Contrast
• Can be combined with small bowel series
• Largely replaced by endoscopy and crosssectional imaging
• Fairly insensitive
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
Small Bowel Series
Small Bowel Enteroclysis
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“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
Contrast Enemas
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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
Contrast Enemas
Single Contrast
Barium Enema
Double Contrast
Barium Enema
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
Genitourinary Fluoroscopy
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Cystogram
Voiding cystourethrogram
Retrograde urethrogram
Hysterosalpingogram
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
Cystogram
Cystogram with Intraperitoneal Rupture
Voiding Cystourethrogram
VCUG
• 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
Retrograde Urethrogram
RUG
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Male patients
Pelvic Trauma
Post-infectious: STD- looking for stricture
Different techniques
Meatus occluded and contrast injected into
urethra under fluoro
Retrograde Urethrogram
RUG
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
Musculoskeletal Fluoroscopy
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Fracture/Dislocation reduction
Hardware placement in the OR
Flexion/Extension views of c-spine
Arthrography
– May be performed in conjunction with MRI or
CT
Techniques Relevant to
MSK Radiology
• Radiography (routine and specialized
views)
• CT
• MRI
• US
• Densitometry
• Interventional procedures (arthrography,
percutaneous biopsy/vertebroplasty)
MSK Radiology
Vertebroplasty
MRI—Sagittal Knee
T1 Weighted
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
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
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
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
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
CT
Axial, with oral contrast in stomach
CT
PET
PET/CT
The Power of CT
CTA
(CT Angiography)
CT Cardiac Imaging
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 Pt’s body used to generate image
• Field strength of magnets 0.3-3.0 Tesla
MR Contrast Agents
• Intravenous contrast---Gadolinium chelatebased 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
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
MRI
Axial, T2-Weighted
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
MRI
Breast Imaging
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
MRI
Sagittal, T1-Weighted
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