Page 179 - Read Online

Misra et al. Vessel Plus 2022;6:32 https://dx.doi.org/10.20517/2574-1209.2021.104 Page 5 of 13

Clinical information
- Cardiac MR (CMR) can provide the following information for the management of most of the patients
with repaired tetralogy of Fallot:

- RV volumetric and function to assess the volume/pressure overload and functional status due to the type
of repair of TOF

- VSD patch and atrial septal defect (ASD) patency to assess the residual intracardiac shunt

- Tricuspid valve regurgitation status and right atrial size

- Evaluation of the RVOT, including prosthetic pulmonary valve for obstruction and/or aneurysm

- Pulmonary regurgitant fraction

- Main and branch pulmonary anatomy to assess obstruction or aneurysm and flow distribution

- LV volumetric and function

- Aortic dimensions to assess aortic ectasia

- Aortic regurgitant fraction

- Coronary artery anatomy

- Myocardial tissue characterization to assess myocardial viability

Technique and clinical information of CMR
CMR is widely considered the gold standard for the quantification of RV size, RV function, PR, and
myocardial tissue characterization in patients with repaired TOF . One of the criteria for pulmonary valve
[10]
placement based on recent guidelines includes mild or moderate RV or LV systolic dysfunction and
enlarged RV dimensions, which are defined as RV end-diastolic volume index greater than or equal to 160
2[12]
mL/m or RV end-systolic volume index > 80 mL/m .
2
Cardiac anatomy and dimensions
After localization, the first images obtained are usually black blood sequences. These include HASTE (half
acquisition single-shot turbo spin-echo), double or triple IR FSE/TSE (inversion-recovery fast spin-
[22]
echo) , or TSE/FSE T1-weighted sequences. However, bright blood cine sequences such as sequential
FLASH (fast low-angle shot), FASTCARD, trueFISP (fast imaging with steady-state precession), or FIESTA
(fast imaging employing steady-state precession) are essential for demonstrating functional pathology, and
for visualizing some intracardiac shunts [23,24] . Cine sequences (GRE, gradient-echo) [Figure 1] are done (i.e.,
static bright blood sequences) to assess the great vessels (i.e., sidedness of the arch, etc.). Cine sequences are
then performed in the long and short axes of the heart, ventricular volumetric, LV outflow tract, and RVOT
[Figure 3], and then through the aortic and pulmonic valve planes to assess for patency and stenoses. Turbo
spin-echo (TSE) imaging [Figure 4] provides a good definition of soft tissue, and has decreased sensitivity to
metallic artifacts compared with gradient-echo sequences.