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

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Presentation on theme: "Advances in Imaging: Echo, CT, CMR Justin D Pearlman MD ME PhD Director, Dartmouth Advanced Imaging Center."— Presentation transcript:

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

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

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

4 Equipment MREcho CT

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

6 Similarities Echo Inject packets of energy waves, pulsed,Inject packets of energy waves, pulsed, Receive echoes Scan to collect data to convert to imageScan to collect data to convert to image TomographicTomographic DynamicDynamic Flow signal from phase shiftFlow signal from phase shiftCMR Insert packets of energy waves, pulsed,Insert packets of energy waves, pulsed, Receive echoes Scan to collect data to convert to imageScan to collect data to convert to image TomographicTomographic DynamicDynamic Flow signal from phase shiftFlow signal from phase shift

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

8 Basis for MRI B0B0 B1B1 MzMz M xy ++  G x,y,z +

9 Magnetism

10 Magnetism

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

12 K-Space

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

14 Fourier Transform

15 Pulse Sequence Gradient Echo (FLASH)

16 Pulse Sequence Inversion Recovery (STIR)

17 Methods Magnetization PreparationMagnetization Preparation ExcitationExcitation Spatial Encoding, EchoesSpatial Encoding, Echoes Image ReconstructionImage Reconstruction Bright Blood TurboGradient Echo, Dark Blood FSEDIR, Fat-suppresive TIR, … (100’s)

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

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

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

21 Self-Triggered MRA

22 Coronary Imaging

23

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 Rest MRI vs. rest Thallium / stress MIBI Total number Disease vessel CABG Angioplasty Table 1: Clinical Characteristics of Study Population Patients N%PrevalenceSE Stent Agreement between Rest MRI and Rest / Stress Nuclear

35 Viability

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

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 No contrastDark Flash3D CT Validation r=.95 Acad Rad 4:680 ’97 Nat Med 1:1085 ‘95 Radiology 214:801 ‘00

41 Dark Flare Predicts Improved Blood Arrival From Angiogenesis Baseline1 Month2 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 Fold-over problem Limit signal to 1 cm 2 Avoid fold-over RME = Response- Modulated Excitation Fold-over No fold-over Look at bowl of kiwi 40 micron resolution

45 Intravascular Imaging

46 What to know VocabularyVocabulary –B 0, B 1, M z, M xy, T 1, T 2, T 2 *, , , ,  –TI, TR, TE, , Matrix, FOV, , TD, TW –GE, SE, FISP, HASTE, … Tilted Tomographic AnatomyTilted Tomographic Anatomy Pathophysiology, Clinical DecisionsPathophysiology, Clinical Decisions Physics, Image ProcessingPhysics, 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

51 Long Axis 3 Chamber View Echo MRI

52 Long Axis 5 Chamber View Echo: WNLMRI: Effusion,Mass

53 Short Axis Cine (Stack) View MRI: Effusion, Mass Echo: WNL

54 Short Axis Stack Cine

55 Clinical Example 63 y.o. Woman63 y.o. Woman Paroxysmal Atrial FibParoxysmal Atrial Fib

56 Long Axis 2 Chamber View Echo: LVHMRI: LVH

57 Long Axis 3 Chamber View Echo: ASHMRI:LVH+RVH

58 Long Axis 4 Chamber View Echo: ASH; lung/RVMRI: LVH+RVH

59 Long Axis 5 Chamber View Echo: “ASH” MRI: LVH+RVH

60 Cine Stacks: RPA stenosis

61 Short Grid Base Cine View Echo: hyperkinetic MRI: Rt septum hypo, order

62 Clinical Example 61 y.o. woman61 y.o. woman Tamoxiphen RxTamoxiphen Rx Idiopathic CHFIdiopathic CHF

63 Long Axis 2 Chamber View EchoMRI

64 Long Axis 4 Chamber View Echo MRI

65 Long Axis 5 Chamber View Echo: ?Good EFMRI: EF 11%

66 Long Axis Rotating Views MRI: DCM,  CS,  IVC

67 Short Axis ( Grid Tag Stack) View Echo: Low EF ?Constriction MRI: DCM, No constriction

68 Clinical Example 60 y.o. Woman s/p L Mastectomy, XRT60 y.o. Woman s/p L Mastectomy, XRT CO=1.0CO=1.0 TR=4+TR=4+

69 4L Chamber View EchoMRI

70 Grid Cine vs. Dobutamine 10ug/kg0 ug/kg20 ug/kg

71 RV Strain vs Dobutamine Rx

72 Apical RV Strain vs. Rx

73 AV Prosthesis

74 Suture Dehiscence

75 Aortic Cusp Aneurysm

76 MR Artifacts Chemical Shift Artifacts : Fat, water yield sum of two shifted images 3.5 PPMChemical Shift Artifacts : Fat, water yield sum of two shifted images 3.5 PPMChemical Shift ArtifactsChemical Shift Artifacts Aliasing : Field of view divides all of space – sine wave is infinite pattern, so copies sumAliasing : Field of view divides all of space – sine wave is infinite pattern, so copies sumAliasing Black Boundary Artifacts : At 1.5 T, 3.5 PPM water - fat shift cancels at 4.5 ms multiples from 2.3 ms, eg 6.8, 11.3, and 15.9 ms. Avoid with TE's close to 4.5, 9, 13.6,....Black Boundary Artifacts : At 1.5 T, 3.5 PPM water - fat shift cancels at 4.5 ms multiples from 2.3 ms, eg 6.8, 11.3, and 15.9 ms. Avoid with TE's close to 4.5, 9, 13.6,....Black Boundary ArtifactsBlack Boundary Artifacts Gibbs or Truncation Artifacts : RingingGibbs or Truncation Artifacts : RingingGibbs or Truncation ArtifactsGibbs or Truncation Artifacts Zipper Artifacts : Door openZipper Artifacts : Door openZipper ArtifactsZipper Artifacts Phase-encoded Motion Artifacts : GhostsPhase-encoded Motion Artifacts : GhostsPhase-encoded Motion ArtifactsPhase-encoded Motion Artifacts Entry Slice Phenomenon : Artery/Vein dark or bright by slice order; false “clot”Entry Slice Phenomenon : Artery/Vein dark or bright by slice order; false “clot”Entry Slice PhenomenonEntry Slice Phenomenon Slice-overlap Artifacts : FadedSlice-overlap Artifacts : FadedSlice-overlap ArtifactsSlice-overlap Artifacts Magic Angle Effects : Tendon gets T2 increased 100x at 55 angulationMagic Angle Effects : Tendon gets T2 increased 100x at 55 angulationMagic Angle EffectsMagic Angle Effects Moire Fringes : Aliasing + Phase differences R/LMoire Fringes : Aliasing + Phase differences R/LMoire FringesMoire Fringes RF Overflow Artifacts : Washed outRF Overflow Artifacts : Washed outRF Overflow ArtifactsRF Overflow Artifacts Central Point Artifact : SpikeCentral Point Artifact : SpikeCentral Point ArtifactCentral Point Artifact Susceptibility Artifacts : Microscopic gradients -> Bright/Dark spotsSusceptibility Artifacts : Microscopic gradients -> Bright/Dark spotsSusceptibility ArtifactsSusceptibility Artifacts Zero-fill Artifact : DC offset -> Gibbs ringing -> Zebra stripesZero-fill Artifact : DC offset -> Gibbs ringing -> Zebra stripesZero-fill Artifact Zero-fill Artifact

77 ! Thank you for your attention Thank you for your attention

78 Key Terms Resonance = Specific matching frequencyResonance = Specific matching frequency Excitation = Sending in a pulsed radiowaveExcitation = Sending in a pulsed radiowave K-space trajectory = Data collection patternK-space trajectory = Data collection pattern Magnetic Field Gradients =Magnetic Field Gradients = –Spatial encoding tool MR Echo is not from tissue interface – it is externally produced from all locations in slice byMR Echo is not from tissue interface – it is externally produced from all locations in slice by –Refocusing Radiowave Pulse –and/or Gradient Reversal Image is produced by “Fourier Transform”Image is produced by “Fourier Transform” –Converts “K-space” data to “X-space” image Pulse Sequence = Sequence of pulses, gradientsPulse Sequence = Sequence of pulses, gradients and steps to get an image or series of images

79 Key Terms T1 = Time to develop magnetizationT1 = Time to develop magnetization Gradient = Magnetic Field Slope low-high in X, Y, or ZGradient = Magnetic Field Slope low-high in X, Y, or Z Gradient-echo = echo caused by reversing X gradientGradient-echo = echo caused by reversing X gradient Spin-echo = echo caused by addition of a radiowave refocusing pulseSpin-echo = echo caused by addition of a radiowave refocusing pulse T2 = Time constant for loss in transverse magnetization with spin-echoT2 = Time constant for loss in transverse magnetization with spin-echo T2*= Time constant for loss in transverse magnetization with gradient-echo; susceptibilityT2*= Time constant for loss in transverse magnetization with gradient-echo; susceptibility TR = “Repetition time” = T1 contrast weightTR = “Repetition time” = T1 contrast weight TE = “Echo time” = T2 or T2* contrast weightTE = “Echo time” = T2 or T2* contrast weight T1 Weighted = method emphasizing T1 differencesT1 Weighted = method emphasizing T1 differences T2 Weighted = method emphasizing T2 differencesT2 Weighted = method emphasizing T2 differences


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