Role of T1 mapping as a complementary tool to T2 for non-invasive cardiac iron overload assessment

• Published in: PloS one Vol. 13; no. 2; p. e0192890
• Main Authors: Torlasco, Camilla, Cassinerio, Elena, Roghi, Alberto, Faini, Andrea, Capecchi, Marco, Abdel-Gadir, Amna, Giannattasio, Cristina, Parati, Gianfranco, Moon, James C, Cappellini, Maria D, Pedrotti, Patrizia
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 21.02.2018; Public Library of Science (PLoS)
• Subjects: Adult; beta-Thalassemia - diagnostic imaging; beta-Thalassemia - physiopathology; Biology and Life Sciences; Blood; Blood - diagnostic imaging; Cardiac Imaging Techniques - methods; Cardiology; Complications and side effects; Diagnosis; Drug dosages; Female; Heart; Heart diseases; Heart failure; Heart surgery; Hospitals; Humans; Iron; Iron metabolism disorders; Iron Overload - diagnostic imaging; Iron Overload - physiopathology; Linear Models; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Mapping; Medicine; Medicine and Health Sciences; Metabolism; Methods; Moon, Maria; Patients; Physical Sciences; Prospective Studies; Regression analysis; Reproducibility; Research and Analysis Methods; Risk factors; Siderosis; Thalassemia; Transfusion; United Kingdom > UK; Italy
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0192890

Iron overload-related heart failure is the principal cause of death in transfusion dependent patients, including those with Thalassemia Major. Linking cardiac siderosis measured by T2* to therapy improves outcomes. T1 mapping can also measure iron; preliminary data suggests it may have higher sensitivity for iron, particularly for early overload (the conventional cut-point for no iron by T2* is 20ms, but this is believed insensitive). We compared T1 mapping to T2* in cardiac iron overload. In a prospectively large single centre study of 138 Thalassemia Major patients and 32 healthy controls, we compared T1 mapping to dark blood and bright blood T2* acquired at 1.5T. Linear regression analysis was used to assess the association of T2* and T1. A "moving window" approach was taken to understand the strength of the association at different levels of iron overload. The relationship between T2* (here dark blood) and T1 is described by a log-log linear regression, which can be split in three different slopes: 1) T2* low, <20ms, r2 = 0.92; 2) T2* = 20-30ms, r2 = 0.48; 3) T2*>30ms, weak relationship. All subjects with T2*<20ms had low T1; among those with T2*>20ms, 38% had low T1 with most of the subjects in the T2* range 20-30ms having a low T1. In established cardiac iron overload, T1 and T2* are concordant. However, in the 20-30ms T2* range, T1 mapping appears to detect iron. These data support previous suggestions that T1 detects missed iron in 1 out of 3 subjects with normal T2*, and that T1 mapping is complementary to T2*. The clinical significance of a low T1 with normal T2* should be further investigated.