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Advances in Imaging: Echo, CT, CMR

Advances in Imaging: Echo, CT, CMR. Justin D Pearlman MD ME PhD Director, Dartmouth Advanced Imaging Center. Disclosures. Consultant for: General Electric Picker/Marconi/Phillips Chiron Boehringer-Ingelheim MagnaLab Perfusion=off-label use of contrast.

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Advances in Imaging: Echo, CT, CMR

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  1. Advances in Imaging:Echo, CT, CMR Justin D Pearlman MD ME PhD Director, Dartmouth Advanced Imaging Center

  2. Disclosures • Consultant for: • General Electric • Picker/Marconi/Phillips • Chiron • Boehringer-Ingelheim • MagnaLab • Perfusion=off-label use of contrast

  3. Dartmouth Advanced Imaging Center - Aims High-end imaging capabilities; Bench->Bedside • 1. Realtime CMR • 2. 4D Cardiac CT • 3. 3D Echo, PET • Viability • Myopathy • Microcirculation • Dx • Rx

  4. Equipment Echo MR CT

  5. Echo short axis CMR short axis Images: CMR vs. Echo Cost: $500-$1500 Cost: $400-800

  6. Echo Inject packets of energy waves, pulsed, Receive echoes Scan to collect data to convert to image Tomographic Dynamic Flow signal from phase shift CMR Insert packets of energy waves, pulsed, Receive echoes Scan to collect data to convert to image Tomographic Dynamic Flow signal from phase shift Similarities

  7. Sound Speed 1540 m/s Echo=A-mode (amp-time) Stopped by Metal Bone Air-tissue Views limited by rib window, contact, angle Resolution depends on frequency, beamwidth Bright blood requires contrast Radiowave Speed 299,792,258 m/s Echo=K-mode (amp-spatial freq) Distorted by Metal (No problems with bone, air/tissue) Any view Resolution is adjustable down to 10 microns, limited by noise and acquisition time Bright blood many ways Differences Echo CMR

  8. Basis for MRI B0 Gx,y,z + B1 Mz Mxy + + 

  9. Magnetism

  10. Magnetism

  11. Change in Magnetization T1/TR 1-e(-TR/T1) 1-2e(-TI/T1) T1/TI T2/TE e(-TE/T2)

  12. K-Space

  13. K-space sums 3,2 2,5 = + Sum (3,2) + 0.5 (2,5) 0.5 (3,2) + (2,5) (3,2) + (2,5)

  14. Fourier Transform

  15. Pulse SequenceGradient Echo (FLASH)

  16. Pulse SequenceInversion Recovery (STIR)

  17. Methods • Magnetization Preparation • Excitation • Spatial Encoding, Echoes • Image Reconstruction Bright Blood TurboGradient Echo, Dark Blood FSEDIR, Fat-suppresive TIR, … (100’s)

  18. Echo Intense Short T1 (if T1-weighted image) Short T2 (if T2-weighted image) Water (if fat suppressed) Fat (if not fat suppressed) Corresponding notions

  19. Fat vs. Fat Suppression: RVD Fat+ vs. Fat- RV RV JDP 2/02

  20. SMART function Pearlman JD et alSerial motion assessment by reference tracking (SMART): application to detection of local functional impact of chronic myocardial ischemia. J Comput Assist Tomogr, 2001. 25(4): p. 558-62

  21. Self-Triggered MRA

  22. Coronary Imaging

  23. Coronary Imaging

  24. Calcium Scoring • Claims: • Negative score may indicate non-cardiac sources of chest pain • Scores over 1,000 predict coronary event within the next 2-3 years • Positive scores referred for catheterization or stress test • BUT significant disease may have negative score • Positive score may be stable plaque

  25. Current Use: Aberrant Coronary Origins

  26. Dynamic CT

  27. Elastic Match of Coronaries • Fast CT of mom • Elastic match  • contrast • Simulated holography as background, for context

  28. Coronary Sinus Rx

  29. 4D CMR

  30. Perfusion-Sensitive Imaging Resting delayed blood arrival predicts ischemia

  31. Rest Delayed Blood Arrival Dark Late Zone Arrived

  32. Space-Time Map We introduced Space- Time Maps to see delay in blood arrival in a single derived image

  33. Perfusion Equitime

  34. Table 1: Clinical Characteristics of Study Population Total number Patients N % Prevalence SE Disease vessel 105 38 97 2.69 0.10 CABG 42 10 26 1.08 0.13 Angioplasty 36 22 56 0.92 0.14 Stent 15 11 28 0.38 0.11 Agreement between Rest MRI and Rest / Stress Nuclear Rest MRI vs. rest Thallium / stress MIBI

  35. Viability

  36. Scar RV TV septum RA LVOT LV lateral LA MV Delayed Enhancement 62 year old patient with 3-vessel CAD c/o angina at rest.Hx MI 1992, PTCA LAD 1992, CABG 1995.Scintigraphy, MRI : lateral + anteroseptal wall defects

  37. Delayed Enhancement vs. Delayed Arrival

  38. Molecular Imaging bFGF2

  39. Microvascular MRI • Tissue bright • Major vessels visible • Dynamic physiology • Small vessels hidden

  40. Angiogenesis-Sensitive MRI r=.95 No contrast Dark Flash 3D CT Validation Radiology 214:801 ‘00 Acad Rad 4:680 ’97 Nat Med 1:1085 ‘95

  41. Dark Flare PredictsImprovedBlood Arrival From Angiogenesis Baseline 1 Month 2 Months

  42. Dark Flare/Delayed Arrival Combined First Dose-Response for Angiogenesis Rx DA=Demand, CX=Response

  43. Angiogenesis imaging may also help diagnose and treat cancer 34 y.o. woman with a palpable breast mass. Ultrasound negative Mammography negative Collateral Sensitive MRI: fat black, collateral neovascular development flashes; cancer found.

  44. MRI Microscopy in Large Target Limit signal to 1 cm2 Fold-over problem Avoid fold-over Look at bowl of kiwi 40 micron resolution RME = Response- Modulated Excitation No fold-over Fold-over

  45. Intravascular Imaging

  46. What to know • Vocabulary • B0, B1, Mz, Mxy, T1, T2, T2*,, ,  ,  • TI, TR, TE, , Matrix, FOV, , TD, TW • GE, SE, FISP, HASTE, … • Tilted Tomographic Anatomy • Pathophysiology, Clinical Decisions • Physics, Image Processing

  47. Echo vs. CMR CMR Echo “Both are watching out for the CAT skinner”

  48. Clinical Example • 42 y.o. man with large cell lymphoma • Radiation to chest • Paroxysmal atrial fibrillation • CT: Mediastinal mass ? LA compression

  49. Long Axis 4 Chamber View Echo MRI: mass, effusion

  50. Long Axis 2 Chamber View Echo: ? NL fxn MRI:effusion,mass

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