Additional value of cardiac magnetic resonance parametric mapping in tissue characterization of common benign paediatric cardiac tumours.

Aims: Cardiac magnetic resonance (CMR) parametric mapping is underexplored in cardiac tumours. To evaluate the contribution of mapping sequences on the characterization of paediatric tumours.

Methods And Results: All paediatric patients referred for cardiac tumours at Bambino Gesù Children's Hospital from June 2017 to November 2023, who underwent CMR with mapping sequences, were included. The diagnosis of tumour type was performed according to signal characteristics on different sequences. Mass parametric mapping for each subtype and interobserver variability was assessed. Sixteen patients were enrolled. The mean age at CMR was 7 ± 5 years. 'Traditional' mass type assessment diagnosed haemangioma (Group A) in three patients (19%), fibroma (Group B) in four patients (25%), rhabdomyoma (Group C) in six patients (37%), and lipoma (Group D) in three patients (19%). The analysis of variance analysis revealed significant differences in mass native T1 and mass extracellular volume (ECV) values among the four subgroups (P < 0.001 for both comparisons). The mean native T1 and ECV values were respectively 1465 ± 158 ms and 54 ± 4% for Group A, 860 ± 118 ms and 93 ± 4% for Group B, 1007 ± 57 ms and 23 ± 5% for Group C, and 215 ± 13 ms and 0 ± 0% for Group D.

Conclusion: Mass mapping analysis is feasible and reproducible in children. ECV values provide the most accurate differentiation. Mass ECV consistently resembles normal myocardium in rhabdomyoma, is extremely high (approaching 100%) in fibroma, equals to zero in lipoma, and matches blood pool ECV (1-Hct) in haemangioma.