This study analyzed the native T1 and T2 values of a population of Maltese healthy individuals using the 3T Siemens Vida scanner at Mater Dei Hospital, Malta. The aim of the study was to establish parametric mapping service in Malta. This is the first study on native T1 and T2 reference values for Caucasian Maltese population.
As reported previously, several factors influence T1/T2 reference values, including scanner vendor, strength of magnetic field, age, and gender. Due to these factors, the SCMR guidelines recommend the use of local reference ranges for native T1 and T2 mapping; if local reference ranges are not available, quantitative results should not be reported clinically.4
Several studies have been conducted to establish native T1 and T2 values in various populations of healthy volunteers (Table 2). Native T1 and T2 values were compared across studies (Fig. 4 and Fig. 5).
The native T1 and T2 values established in this study correlate closely with those by Pons-Lladó (1230 ± 38.5 ms for native T1 and 39 ± 2.2 ms for T2) who used the exact same vendor and type of scanner (Siemens MAGNETOM Vida), magnetic field, and sequence as the present study.5 Native T1 values in the present study were also similar to those by Teixeira et al. (1207.9 ± 18.2 ms for native T1) who used the same vendor (Siemens), magnetic field, and pulse sequence.6 Nonetheless, minor differences in native T1 and T2 values were seen between the present study and Lee et al. (1266.03 ± 32.86 ms for native T1 and 40.09 ± 2.45 ms for T2 ).7 The dissimilarity in native T1 values between the studies by Pons-Llado, Teixeira et al., Lee et al. and the present study with those reported by Roy et al. (1162 ± 81 ms),8 and Tribuna et al. (1124.9 ± 55.2 ms)9 could be explained by the variance in scanner vendor. Furthermore, 73% of participants in the study by Roy et al. had at least one cardiovascular risk factor.
With regards to T2 values, the variance between our values and T2 values seen in Roy et al. (52 ± 7.0 ms)8 and Grantiz et al. (51.6 ± 3.0 ms)10 may be explained by the variance in vendor and pulse sequence utilized in these studies, as previously described by Baeßler et al.11 Of note, there is a clinical relevant inter-scanner variability in T2 values, which causes major drawbacks for the clinical implementation of this technique across different sites.11 Additionally, mean T2 times vary significantly according to different magnetic field strengths.
Myocardial native T1 and T2 mapping is useful in detecting a range of myocardial diseases such as myocarditis, infiltrative myocardial disease (including Anderson-Fabry disease and cardiac amyloidosis), as well as for assessing the etiology of heart failure. Furthermore, this technique can assist clinicians in assessing disease progression and response to treatment. Therefore, standardization of parametric values across different vendors and scanners is imperative. A strong collaboration between vendors may help in standardizing reference values for parametric mapping.
Table 2
Studies Examining Native T1 and T2 Values
Study | Country of Study Sample Size | Vendor and Strength of Magnetic Field | Sequence for Native T1 Value | Native T1 Value, mean ± SD | Sequence for T2 Value | T2 Value, mean ± SD |
Pons-Lladó5 | Spain n = 24 | Siemens MAGNETOM Vida (3T) | MOLLI 5(3)3 | 1230 ± 38.5 ms | GRE/ FLASH | 39 ± 2.2 ms |
Teixeira et al.6 | Canada n = 40 | Siemens MAGNETOM Skyra (3T) | MOLLI 5(3)3 | 1207.9 ± 18.2 ms | – | – |
Lee et al.7 | Republic of Korea n = 12 | Siemens Verio (3T) | MOLLI 5(3)3 | 1266.03 ± 32.86 ms | GRE | 40.09 ± 2.45 ms |
Roy et al.8 | Belgium n = 75 | Philips Ingenia (3T) | MOLLI 3(3)3(3)5 | 1162 ± 81 ms | GraSE | 52 ± 7.0 ms |
Tribuna et al.9 | Portugal n = 22 | Canon Vantage Galan (3T) | MOLLI 5(3)3 | 1124.9 ± 55.2 ms | – | – |
Grantiz et al.10 | Austria n = 60 | Philips Achieva (3T) | MOLLI 5(3)3 | 1183.8 ± 37.5 ms | GraSE | 51.6 ± 3.0 ms |
Present Study | Malta n = 51 | Siemens MAGNETOM Vida (3T) | MOLLI 5(3)3 | 1200.1 ± 30.7 ms | GRE/ FLASH | 39.5 ± 1.8 ms |