Perbandingan pemeriksaan N-terminal pro-B-type natriuretic peptide (NT-PROBNP) dengan magnetic resonance imaging (MRI) T2* jantung untuk mendeteksi hemosiderosis jantung pasien thalassemia β mayor remaja = Detection of cardiac hemosiderosis in adolescent thalassemia patient using N-terminal pro-B-type natriuretic peptide (NT-PROBNP) and cardiac magnetic resonance imaging (MRI) T2*