1. “How we do” CMR in acute myocardial infarction
Derek J Hausenloy, Anna S Herrey, James C Moon UCLH Heart Hospital and
The Hatter Institute, University College London, UK.
This presentation posted for members of SCMR
as an educational guide – it represents the views and
practicesof the author, and not necessarily those of SCMR.

2. CMR in acute myocardial infarction
Established indications in AMI STEMI:
Assess global and regional LV function.
Detect LV thrombus.
Detect and quantify microvascular obstruction.
Detect and quantify acute myocardial infarct size
Detect and quantify preserved myocardium.
Potential future indications in STEMI:
Detect and quantify the area at risk of infarction- myocardial oedema.
Determine the myocardial salvage index
(infarct size-area at risk/area at risk)
Detect and quantify myocardial haemorrhage.
Detect and quantify the peri-infarct ‘grey’ zone.
Coronal
Transverse 1
Transverse 2

3. CMR and other Imaging Modalities in AMI
Function
Infarct
Thrombus
MVO
Radiation
Dose
Haem
Area
at risk
Myocardial
salvage
Cardiac MRI
+++ ++
Nuclear +
Echo
Cardiac CT
Coronal
Transverse 1
Transverse 2

4. Facilitating CMR in AMI
Fine balance between time available and completeness of protocol.
Need to optimize protocol to <45 min.
Non breath-hold approaches to CMR:
3D whole heart navigated sequences
Single-shot LGE
Motion corrected averaging
Coronal
Transverse 1
Transverse 2

5. CMR in AMI – general considerations
Aim to image on day 2-3 i.e. on day of discharge, although safe within 24 hours
Phrommintikul et al Eur J Radiol Apr 16. [Epub]
Coronary stents are not a problem
Patel et al Radiology. 2006;240(3):
Patient may still be unwell
Difficulty breath holding and tachycardia in patient
Ensure resuscitation facilities nearby
Check renal function. If eGFR<30, only rarely does the benefits of CMR outweigh risk of contrast (NSF)
Aim to complete scan within 45 minutes
Coronal
Transverse 1
Transverse 2

6. Summary of CMR protocol for AMI
Axial scouts Time
Multi-slice SSFP cine MRI in long and short axes
for volumes and function.
(see ‘How I do a volume study’) 10 min
Early post-contrast T1-weighted 2D inversion-
recovery GRE (or SSFP) with long TI. Multi-slice:
a. MVO (presence and size)
b. Acute thrombus min
5-15 min post-contrast T1-weighted 2D inversion-recovery GRE (or SSFP). Multislice for:
a. Infarct (presence and size)
b. MVO (presence and size) min
Coronal
Transverse 1
Transverse 2

7. Optional imaging for AMI
Time
2a Optional – before giving contrast: Multi-slice T2
weighted TIRM or STIR for:
a. Area at risk (size)
b. Myocardial haemorrhage (presence and size). +15 min
2b Optional resting perfusion – minimum 3 SA slices
– basal, mid, apical for:
a. no-reflow (microvascular obstruction) min
Coronal
Transverse 1

8. Early gadolinium enhancement
- 1-3 min post-gadolinium, IR GRE or SSFP sequence, 2D or 3D set inversion time to ~440ms-480ms (higher if ↓HR or trigger 1)
- To detect intra-cardiac thrombus (see arrow).
RCA clip artefact

9. Late Gadolinium Enhancement (LGE) - 1
- Quantification of myocardial infarct size
- T1 inversion recovery sequence (GRE or SSFP)
- Usually image in diastole to reduce motion artefacts
- Manually adjust TI (start depends on time, dose and trigger/HR)

10. Late gadolinium enhancement (2)
Can also detect and quantify MVO (dark core –see arrow).
presence of MVO linked to worse clinical outcomes
preventing MVO is a viable target/mechanism for cardioprotection

11. Late gadolinium enhancement (3)
Further LGE information: see
AMI ‘Resources’ section of SCMR website
(includes protocols, cases, standardized datasets, talks)
2D Inversion recovery sequence (GRE)
- Alternatives: IR–SSFP, 3D sequences, PS-IR
Image in diastole to reduce motion artefacts.
Endocardial structures: systole (reduce segments) and later (blood pool down)
Image technique
Go and learn it. artefact recognition and reduction
Manually adjust TI (260ms-480ms)
Compulsory –even PS-IR sequences work better
Gd dose: if not already given, use mmol/kg
Image positions: Copy from cines, phase swaps, cross cuts

12. Optional imaging -T2 oedema imaging (1)
- Myocardial oedema/inflammation appear as increased signal intensity on T2-weighted sequences (see AMI ‘Resources’ talks on T2W imaging)
This can be used to detect an AMI, myocarditis, or delineate the ‘area at risk of infarction’.
Several T2 weighted sequence e.g. TSE (black blood), STIR, TIRM, T2P-SSFP, ACUT2E.
T2 TSE
TIRM
Area at Risk
Area at Risk

13. Optional imaging -T2 oedema imaging (2)
Problems with T2 oedema imaging
Low SNR
-therefore difficult to delineate and quantify.
Surface coil sensitivity
-T2 sequences are very prone to variations
Bright subendocardial rims
-due to stagnant blood.
Posterior wall signal loss
-due to cardiac movement,

14. Optional imaging –Myocardial hemorrhage
The presence of myocardial hemorrhage within the infarct is
associated with worse LV remodelling and clinical outcomes.
It can be detected using either STIR or dual-inversion black-blood gradient multi-echo T2* imaging sequences.
Hypointense region on T2 weighted imaging.
Appears to correspond to area of MVO.
Early Gd
Ganame et al Eur Heart J 2009 Apr Epub
LGE
STIR imaging
O’Regan et al Radiology 2009;250:
LGE
T2* imaging
Perfusion

15. Optional imaging – Rest perfusion
- Myocardial perfusion imaging (<1 min post-gadolinium).
- To detect/quantify microvascular obstruction (see arrow).
- See “How we do perfusion”

16. Optional imaging – Peri-infarct ‘grey’ zone
Detecting and quantification of the peri-infarct ‘grey’ zone (intermediate contrast), which is associated with post-infarct sudden cardiac death, may be used for risk-stratification post-MI. Yan et al Circ 2006;114;32-39
Schmidt et al Circ 2007;115;
Detect using LGE and quantify using thresholds (SD±2-3) or full-width half max.
See ‘On-Line talks: (copy and paste these into your browser)
From Schmidt et al, above

17. LGE Example- LAD infarct Cine TIRM Perfusion LGE
Acknowledgement:: Derek Hausenloy