‘how i do’ : cmr of repaired tetralogy of fallot sonya v. babu-narayan mb bs bsc mrcp department...
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‘How I do’ : CMR of repaired tetralogy of Fallot
‘How I do’: CMR of repaired tetralogy of Fallot
Sonya V. Babu-Narayan MB BS BSc MRCP
Department of CMRRoyal Brompton Hospital
For scmr.org 07/2006
This presentation posted for members of scmr as an educational guide – it represents the views and practices of the
author, and not necessarily those of SCMR.
‘How I do’ : CMR of repaired tetralogy of Fallot
CMR in repaired tetralogy of Fallot
Include:
• Measurements of biventricular volumes,
EF, mass
• RVOT cines, 2 views
• Aortic root +/- AR quantification
• Quantify pulmonary regurgitant fraction
• Assessment of LPA and RPA
• Ensure reproducible technique:
– Serial CMR aids PVR timing
Brickner, M. E. et al. N Engl J Med 2000;342:334-342
‘How I do’ : CMR of repaired tetralogy of Fallot
“Basic Recipe” (~ 30 mins) • 3 axis multislice stack: Transverse, sagittal, coronal
– Use Half Fourier single shot TSE or single shot SSFP• Initial pilots then: • cines
– 2Ch, 4Ch and SA stack – RVOT – 2 views– LVOT – 2 views
• Velocity mapping – Pulmonary regurgitant fraction (PRF)
All patients
Consider
• AoV view cine for measurement aortic root • Branch PAs if not clearly unobstructed on transverse stack• Further long axis RV views: RV “in and out”/ oblique/2ch (see below)
• Further velocity mapping• 2 views for peak PA velocity • Ao to add to PA for PRF above for Qp:Qs shunt calculation • Branch PA velocity mapping
• 3d angiography• MAPCA’s / planning intervention (eg transcatheter PV implantation)
‘How I do’ : CMR of repaired tetralogy of Fallot
Initial Acquisition
Multislice stack in transverse, sagittal and coronal Multislice stack in transverse, sagittal and coronal – We do: transverse half Fourier TSE, and SSFP for coronal + sagittal We do: transverse half Fourier TSE, and SSFP for coronal + sagittal
• transverse half Fourier TSE; easier to measure dimensions of structures such as aortic root and transverse half Fourier TSE; easier to measure dimensions of structures such as aortic root and SSFP multislice gives advantage of jet recognition early onSSFP multislice gives advantage of jet recognition early on
Advantages of comprehensive multislice imaging include:Advantages of comprehensive multislice imaging include:– subsequent piloting of cines subsequent piloting of cines – ability to answer specific additional questions retrospectivelyability to answer specific additional questions retrospectively
• such as presence of LSVC?such as presence of LSVC?• right aortic arch?right aortic arch?• location of coronary sinus?location of coronary sinus?
‘How I do’ : CMR of repaired tetralogy of Fallot
How to obtain a good RVOT view
‘How I do’ : CMR of repaired tetralogy of Fallot
How to obtain a good RVOT view cross cut
You may now wish to append your first RVOT view and realign the plane locating on this second cross cut RVOT to improve alignment further
These two views provide a minimum data set for alignment of velocity acquisitions
RVOT “cross-cut”
RVOT
‘How I do’ : CMR of repaired tetralogy of Fallot
Advantages in RVOT obstruction
• Characterisation level of obstruction and flow;– sub-infundibular stenosis
– assessment of branch PAs
• Unrestricted views of RV anatomy– multiplanar
• Assessment of associated abnormalities
• Anterior conduits well visualised
Infundibular pulmonary stenosis
‘How I do’ : CMR of repaired tetralogy of Fallot
Pulmonary regurgitant fraction
In practice, use other views to check alignment – at least one other RVOT plane (RVOT cross-cut above) and potentially the transaxial haste, a bifurcation PA view, in-plane velocity mapping or oblique RV view
‘How I do’ : CMR of repaired tetralogy of Fallot
Ventricular volumes
Other download say thisEg How I do LV volumes
‘How I do’ : CMR of repaired tetralogy of Fallot
How to obtain a good RPA cine
RPA
‘How I do’ : CMR of repaired tetralogy of Fallot
How to obtain a good LPA cine
Adjustment on coronal multislice useful
LPA
‘How I do’ : CMR of repaired tetralogy of Fallot
How to obtain a bifurcation PA cine
If the LPA is markedly higher in take off than the RPA it may be impossible to align a bifurcation cine view
PA Bifurcation cine
‘How I do’ : CMR of repaired tetralogy of Fallot
Assessment of LPA Stenosis
Cine In-plane flow Through plane flow
Assessment of branch pulmonary artery stenosis is important in repaired Fallot as these may be a therapeutic target particularly if there is significant pulmonary regurgitation
Mild LPA origin stenosisUse in-plane to help align through-plane for more accurate peak velocity location or better alignment
for flow volume measurements
NBH velocity mapping at RPA and LPA can be used to quantify flow to R and L lung respectively, that is, differential lung perfusion (nb. normally greater flow to the R lung than the L lung)
Lack of pulsatility in distal pulmonary vessels may suggest more significant stenosis
‘How I do’ : CMR of repaired tetralogy of Fallot
RVOT Akinesia/Aneurysm
Davlouros et al, JACC 2002
Dyskinetic and or aneurysmal areas of the RVOT are frequently present in adults with repaired tetralogy of Fallot and vary in size
‘How I do’ : CMR of repaired tetralogy of Fallot
RV measurement in ACHD
• RV trabeculations: – Coarse, thickened – significant in summed volume – Planimetry challenging
• Determining valve level may be difficult– TV: may be difficult – PV: potentially absent or remnant
• RVOT – can be dilated and dyskinetic – may have no effective pulmonary valve– We count a dilated or aneurysmal RVOT as part of the RV
• it lies beneath the PV annulus • So belongs to the right ventricle
• Use stroke volume as check– velocity mapping of Ao and Pa – a useful cross-check on manual contour data
• Establish your own, reproducible protocol for the RV
‘How I do’ : CMR of repaired tetralogy of Fallot
Residual defects, associated abnormalities, post-operative complications, variants
• The following may be present:– Residual VSD
– Residual PS
– Other intra-cardiac associated abnormalities • eg ASD, AVSD, PFO
– Left SVC
– Right aortic arch
– Branch PA deformation or stenosis
– Ascending aortopathy / aortic root dilatation
– MAPCA’s if pulmonary atresia variant
– Proximity of structures to retro-sternum pre redo surgery
– LV as well as RV dysfunction
– FREE PR after repair
‘How I do’ : CMR of repaired tetralogy of Fallot
Identifying residual VSD / patch leak
• Patch leak may be seen in:– LVOT view – RV in and out – RV oblique views– SA view as opposite
• If uncertain:– cross-cut a SA view where a jet core is
suspected
• Add NBH velocity:– Aorta and PA – Calculate Qp:Qs ratio – Stroke volume ratio may be relevant
‘How I do’ : CMR of repaired tetralogy of Fallot
Additional RV Long Axis Views
These additional RV views can be useful in contributing to qualitative assessment of regional and global RV function. Residual VSD patch leak is sometimes well seen on the
“RV in and Out” cine which shows the AoV in SA and the VSD patch as well as PV and TV
‘How I do’ : CMR of repaired tetralogy of Fallot
•LV pathology is less common
•Evidence of fibrosis is: – in specific locations – to varying extent – sometimes in areas
remote from surgical sites
•Increased LGE relates to– exercise intolerance– neurohormonal activation– ventricular dysfunction
Babu-Narayan SV et al. Circulation 2006;113:405-413
•RV LGE Score predicted clinical arrhythmia
•LGE CMR can be extended to the sub-pulmonary, hypertrophied RV and appears sensitive & surgical scarring appears ubiquitous in older repaired TOF
Late Gadolinium In Fallot - Research
‘How I do’ : CMR of repaired tetralogy of Fallot
Late Gadolinium In Fallot - Clinical
• Prospective data pending -a hot research topic• May be useful with LV dysfunction•Can be challenging
• Adult patients have surgical scarring• Flow-limiting CAD uncommon without symptoms• Caution when interpreting small areas of LGE
•Call abnormality only if proven in 2 views• phase swap, cross-cutting, or both