Abstract:

Objective To investigate the application of magnetic resonance imaging (MRI) in the follow-up after surgery for tetralogy of Fallot (TOF). Methods Seventy-one patients were examined with MRI during follow up after surgery for TOF, and the scanning sequences included  fast imaging employing steady-state acquisition (FIESTA), phase-contrast magnetic resonance imaging (PCMR) and contrast enhanced magnetic resonance angiography (CE-MRA). Results Branch pulmonary artery stenosis was detected by CE-MRA in 44 of 71 (62.0%) patients, including left pulmonary artery stenosis (n=29, 40.8%), right pulmonary artery stenosis (n=4, 5.6%) and both left and right pulmonary artery stenosis (n=11, 15.5%). With FIESTA sequence, right ventricular enddiastolic volume was measured at (115.28±15.18) mL/m2. Varied amount of pulmonary regurgitation (42.12%±16.30%) occurred in all 38 cases with PCMR. Meanwhile, serious pulmonary regurgitation was observed in 14 cases (36.8%), with pulmonary artery regurgitant fraction >40%. In patients without branch pulmonary artery stenosis, regurgitant fraction of the left pulmonary artery (57.70%±21.99%) was significantly higher than that of the right pulmonary artery (30.32%±13.44%)(P<0.01). Delayed onset of the tricuspid valve flow was observed by PCMR in 18 (54.5%) of 33 patients. However, there was no significant difference in the pulmonary artery regurgitant fraction, right ventricular ejection fraction and right ventricular end-diastolic volume index  between patients with and without delayed onset of the tricuspid valve flow (P>0.05). Conclusion Left pulmonary stenosis, pulmonary regurgitation and right ventricular enlargement are common complications after surgery for TOF. MRI can provide adequate information on residual anatomical problems and functional evaluation, which makes it ideally suited to the evaluation of  patients after surgery for TOF.

Key words: magnetic resonance imaging, congenital heart disease, tetralogy of Fallot, post-operation