1. Cardiovascular Imaging in Renal Failure?
Prof Graeme Houston
Dundee
This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no
Dundee July 2016

2. Cardiovascular Imaging

3. Cardiovascular Imaging 2016
Ultrasound – Percutaneous, IVUS
Catheter Angiography
Nuclear Medicine
MRI
Multislice CT
PET

4. Cardiovascular MRI Cardiac MRI Vascular MRI
Established as a routine clinical technique since 2003
Patients are scanned to answer specific clinical questions that cannot be obtained through other means
Vascular MRI
Established clinical technique routinely since 1998
Potential extensions to existing techniques to complement the service

5. Renal Failure and the Heart
Fluid overload – left ventricular failure
Renal cardiomyopathy - uraemic
Increased coronary arterial disease
Immunosuppression in renal transplantation
Vascular access load
Drug toxicity
Underlying cause of renal failure

6. Capabilities of Cardiac MRI
Morphology and function (white blood cine, black blood spin echo)
Valve assessment
Flow quantification
Perfusion
Viability (delayed enhancement)

7. Basic morphology
Steady-state sequences give good anatomical images with bright-blood contrast. Cine imaging is possible with images created that cover the whole cardiac cycle. Example images from a patient with LVH

8. Thrombus in right atrium
Black blood imaging shows up thrombus well

9. Right Atrial tumour
Cine scans demonstrate heart function with tumour present. Black blood post-contrast shows extent

10. Qualitative cardiac assessment
White blood cine scans in 2 chamber, 4 chamber and short axis orientations in a patient with poor cardiac function

11. Quantitative LV assessment
Acquire a stack of SA cine views from the base to the apex of the heart

12. Quantitative LV assessment
By defining the endocardial and epicardial borders it is possible to calculate blood pool and left ventricular volume in each phase by considering the myocardium as a series of rings
Distance between slices
Apex
Base

13. LV function
Possible to build up a graph showing the filling and emptying of the LV
ED phase
ES phase
In practice, only calculate the volumes at ED and ES as this allows the ejection fraction, stroke volume and the LV mass to be calculated
LV blood pool volume / ml
Time from R-wave trigger / ms

14. Quantitative cardiac reporting
Reports of quantitative results (LVM and function) can be generated either as paper copies or electronic reports

15. Morphology with black blood Spin Echo
Black blood scans give T1 weighing to images. Can also use fat suppression (black blood STIR)
Black blood (double IR)
Black blood STIR (triple IR)

16. Right ventricular assessment
Use black blood and black blood STIR scans to look for fatty infiltration into the right ventricular wall
Black Blood
Black Blood STIR

17. Flow imaging Magnitude Phase
Cine phase contrast imaging. Phase image is a measure of the velocity of the blood flow. mid-grey is stationary, black and white indicates flow either into or out of the slice, depending on how the scan has been set up

18. Quantitative flow analysis: Coarctation

19. Mitral and right AV valves
Looking at valves
Aortic valves
Mitral and right AV valves

20. Bicuspid aortic valve

21. First pass perfusion imaging

22. Quantitative perfusion analysis
Possible to measure uptake of contrast agent in the myocardium
Draw contours around the myocardium, divide the myocardium into sectors and propagate through the time series

23. Quantitative perfusion analysis
Calculate uptake parameters for each sector of the myocardium
tfoot
tpeak
Slope
peak
Area under curve
foot

24. Quantitative perfusion analysis
Quantitative data can be summarised on bull’s-eye plots
Peak
Slope
Area

25. Tissue enhancement Fibrosis/viability
Phase-sensitive inversion-recovery short axis views approximately 10 minutes after contrast agent injection in a patient with suspected myocardial sarcoidosis

26. Myocardial Viability Acute MI
Acute inferior MI – 4 days
LV Morphology and Function

27. Delayed Gd Enhancement:
Mid Inferior and Mid Inferiorospetal
50% wall thickness enhancement
Role in prediction response revascularisation

28. Questions Cardiac MRI? Summary: Function Flow-ology Lumen-ology
Wall-ology
Perfusion-ology

29. Summary: Cardiac MRI
Morphology and function (white blood cine, black blood spin echo)
Valve assessment
Flow quantification
Perfusion
Viability (delayed enhancement)

30. Vascular Imaging

31. Vascular MRI

32. Vascular MRI Lumen-ology Wall-ology Perfusion-ology Flow-ology
Function

33. Cardiovascular MRI: Whole Body Atheroma
Whole Body MRI
Overview of atheroma
High Resolution at disease site
Focussed assessment of plaque morphology
Large Vessel Compliance
JG Houston

34. Whole body MRA – Atheroma Burden
“Lesion” MRA -
Index atheroma lesion

35. Carotid MRI “Wall-ology”
1.5 Tesla machine
Dedicated phased-array carotid coil and standard neck coil
Four sequences:
Time of flight [TOF]
T1-weighted [T1W]
Proton density-weighted [PDW]
T2-weighted [T2W]
Series of illustrations of the sequences and resulting images, demonstrating what plaque looks like on each and how comparison of different sequences allows identification of different plaque components

36. Carotid MRI “Wall-ology”
1.5 Tesla machine
Dedicated phased-array carotid coil and standard neck coil
Four sequences:
Time of flight [TOF]
T1-weighted [T1W]
Proton density-weighted [PDW]
T2-weighted [T2W]
Series of illustrations of the sequences and resulting images, demonstrating what plaque looks like on each and how comparison of different sequences allows identification of different plaque components

37. Plaque composition: necrotic core and cap rupture
Focussing in on specific examples of particular “high risk” plaque characteristics: the cracked plaque cap with exposure of the thrombogenic necrotic core to flowing blood
Time of flight T2-weighted

38. Carotid Plaque composition: Necrotic core and cap rupture
Focussing in on specific examples of particular “high risk” plaque characteristics: the cracked plaque cap with exposure of the thrombogenic necrotic core to flowing blood
MRI – Plaque Rupture Histology

39. New Insights Vascular Disease
Anatomy MRI Flow pattern

40. New Insights Vascular Disease Computational Fluid Dynamics
CFD predicted sites of carotid disease based on lack of spiral flow

41. Renal angiography Perfusion20 40 60 80
100 7 14 21 45
120
180
240
Time(Sec)
Signal intensity(a.u)
Aorta
Cortex
Typical Contrast Uptake Curves

42. Renal MRA
Research – How can renal perfusion MRI be used to select patients for renal intervention?

43. Optimal cortical medullary contrast (at TR 4.8ms) achieved at 25-35o50
100
150
200 10 20 30 40 60 70 80 90
Cortex
Medulla
Noise
Contrast
Signal Intensity (a.u)
Flip Angle (/o)
MRI signal intensity v flip angle for porcine kidney tissue using a FLASH sequence
Optimal cortical medullary contrast (at TR 4.8ms) achieved at 25-35o

44. Patient 1036 – moderate (31-50%) RAS on R, severe (70-100%) RAS on L
Pre contrast
Venous phase
Subtraction
Cortical volume
Total volume
Cortical volume
Total volume
144cm3
226cm3
32cm3
77cm3
Patient 1036 – moderate (31-50%) RAS on R, severe (70-100%) RAS on L

45. Kidney Volumes and Lengths
Moderate – Severe Stenosis:
Mean kidney lengths were only reduced by 14%.
Mean kidney volumes were reduced by 39%

46. Cortical Volumes and Function
Mean GFR values dropped as the severity of combined RAS increased.

47. Cardiovascular MRI Summary
Routine tool: Cardiac
Morpholgy, function
Valves
Perfusion
Viability
Routine Vascular tool
“Catheter Angiography Obselete”
Vessel morphology
Flow

48. Acknowledgements Tayside MR Imaging Radiographers Medical Physicists
Wendy Milne
Baljit Jagpal
Medical Physicists
Stephen Gandy
Stephen Nicholas
Shelley Waugh