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. Outline. Introduction X-Rays Fluoroscopy GI GU CT MR Innovative Modalities. Modalities Available in Radiology. Plain Film / X-Ray/Mammography

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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


Outline

  • Introduction

  • X-Rays

  • Fluoroscopy

    • GI

    • GU

  • CT

  • MR

  • Innovative Modalities


Modalities Available in Radiology

  • 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


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


Most Useful Applications for Plain X-Rays

  • Chest

  • Musculoskeletal

  • Abdomen: limited usefulness


Widely available

Inexpensive

Doesn’t require advanced technologist knowledge

Can be performed quickly

Portable

Ionizing Radiation

Relatively insensitive

Requires patient cooperation

Plain X-RaysProsCons


Fluoroscopy

  • Utilizes X-Rays

  • Real-time imaging

  • Utilizes image intensifier

  • Involves use of contrast agents


Main Uses of Fluoroscopy

  • Gastrointestinal Imaging

  • Genitourinary Imaging

  • Angiography

  • Other

    • Intraoperative

    • Foreign body removal

    • Musculoskeletal


Widely Available

Inexpensive

Functional and Anatomic

No sedation required

Requires ingestion/injection of contrast

Patient cooperation

Time consuming

FluoroscopyProsCons


Gastrointestional Fluoroscopy

  • 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

Gastrograffin Swallow Study

Barrium Swallow Study


Barium Sulfate

  • 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

  • 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 cross-sectional 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

  • “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

  • 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

  • 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 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


Retrograde UrethrogramRUG

  • Male patients

  • Pelvic Trauma

  • Post-infectious: STD- looking for stricture

  • Different techniques

  • Meatus occluded and contrast injected into urethra under fluoro


Retrograde UrethrogramRUG


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

  • 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

MRI—Sagittal Knee

T1 Weighted

Vertebroplasty


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 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


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


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