BASIC CONCEPTS IN DIAGNOSTIC IMAGING

1. BASIC CONCEPTS IN DIAGNOSTIC IMAGING J.J. Jimenez, M.D. A. Tamrazi PhD Carle Clinic Association University of Illinois College of Medicine

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

3. Modalities Available in Radiology • Plain Film / X-Ray/Mammography • Fluoroscopy • Ultrasound • CT • MRI • Nuclear Medicine/Molecular Imaging • Angiography/Interventional

5. Relative Cost of Imaging Studies

6. Relative Availability of Diagnostic Imaging

7. 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

8. Most Useful Applications for Plain X-Rays • Chest • Musculoskeletal • Abdomen: limited usefulness

9. Widely available Inexpensive Doesn’t require advanced technologist knowledge Can be performed quickly Portable Ionizing Radiation Relatively insensitive Requires patient cooperation Plain X-RaysPros Cons

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

11. Main Uses of Fluoroscopy • Gastrointestinal Imaging • Genitourinary Imaging • Angiography • Other • Intraoperative • Foreign body removal • Musculoskeletal

12. Widely Available Inexpensive Functional and Anatomic No sedation required Requires ingestion/injection of contrast Patient cooperation Time consuming FluoroscopyPros Cons

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

14. 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

15. Single Contrast vs Double Contrast Single Contrast Barium Enema Double Contrast Barium Enema

16. 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

17. Barium vs Gastrograffin Gastrograffin Swallow Study Barrium Swallow Study

18. Barium Sulfate • Most widely used • Better images than gastrograffin • ‘Chalky taste’ • Peritonitis may develop if perforation • If delayed transit, may form concretions in colon

19. 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

20. 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

21. Esophogram or Barium Swallow • Evaluates pharynx and esophagus • Limited evaluation of stomach • Double or Single Contrast • Mucosal contour and Motility

22. 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

23. Modified Barium Swallow

24. 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

25. 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

26. Small Bowel Series

27. 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

28. 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

29. Contrast Enemas Single Contrast Barium Enema Double Contrast Barium Enema

30. 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

31. Genitourinary Fluoroscopy • Cystogram • Voiding cystourethrogram • Retrograde urethrogram • Hysterosalpingogram

32. 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

33. Cystogram Cystogram with Intraperitoneal Rupture

34. 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

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

36. Retrograde UrethrogramRUG

37. 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

38. 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

39. Techniques Relevant to MSK Radiology • Radiography (routine and specialized views) • CT • MRI • US • Densitometry • Interventional procedures (arthrography, percutaneous biopsy/vertebroplasty)

40. MSK Radiology MRI—Sagittal Knee T1 Weighted Vertebroplasty

41. 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

42. 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

43. 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

44. 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

45. 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

46. CT Axial, with oral contrast in stomach

47. CT PET PET/CT

48. The Power of CT CTA (CT Angiography) CT Cardiac Imaging

49. 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

50. 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