‘How I do’: CMR of repaired tetralogy of Fallot

Sonya V. Babu-Narayan MB BS BSc MRCP Department of CMR Royal 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.

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‘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

All patients

•

Velocity mapping

– Pulmonary regurgitant fraction (PRF) • 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 Consider

Initial Acquisition

Multislice stack in transverse, sagittal and coronal – 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 SSFP multislice gives advantage of jet recognition early on Advantages of comprehensive multislice imaging include: – subsequent piloting of cines – ability to answer specific additional questions retrospectively • such as presence of LSVC?

• right aortic arch?

• 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

RVOT RVOT “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

‘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 this Eg How I do LV volumes

‘How I do’ : CMR of repaired tetralogy of Fallot

How to obtain a good RPA cine

‘How I do’ : CMR of repaired tetralogy of Fallot RPA

How to obtain a good LPA cine

Adjustment on coronal multislice useful

‘How I do’ : CMR of repaired tetralogy of Fallot LPA

How to obtain a bifurcation PA cine

PA Bifurcation cine

If the LPA is markedly higher in take off than the RPA it may be impossible to align a bifurcation cine view

‘How I do’ : CMR of repaired tetralogy of Fallot

Assessment of LPA Stenosis

Cine In-plane flow Through plane flow

Mild LPA origin stenosis

Use 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

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 ‘How I do’ : CMR of repaired tetralogy of Fallot

RVOT Akinesia/Aneurysm

Dyskinetic and or aneurysmal areas of the RVOT are frequently present in adults with repaired tetralogy of Fallot and vary in size

Davlouros et al, JACC 2002

‘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

Late Gadolinium In Fallot - Research

•LGE CMR can be extended to the sub-pulmonary, hypertrophied RV and appears sensitive & surgical scarring appears ubiquitous in older repaired TOF •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 •

RV LGE Score predicted clinical arrhythmia Babu-Narayan SV et al. Circulation 2006;113:405-413 ‘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

‘How I do’ : CMR of repaired tetralogy of Fallot