Normal Reference Values for 3T Cardiac Parametric Mapping

Cardiac MRI represents the gold standard for the in vivo differentiation of various types of cardiomyopathies, thanks to its ability to characterize tissue. Through specific parametric mapping sequences, cardiac MRI allows not only the identification but also the quantification of both focal and diffuse alterations that cannot be assessed with other techniques. These sequences enable the direct measurement of relaxation times T1 (spin-lattice) and T2 (spin-spin), expressed in milliseconds, thus providing the ability to differentiate various tissue alterations (e.g., inflammation, ischemia, edema, and fibrosis).

The usefulness of T1 mapping sequences in analyzing certain cardiomyopathies, such as cardiac involvement in Anderson-Fabry disease, amyloidosis, and hemochromatosis, is well-documented in the literature. Similarly, T2 mapping sequences are valuable for evaluating inflammatory processes and myocarditis. Parametric sequences are also used to assess rejection phenomena in patients undergoing cardiac transplantation and play a crucial role in evaluating various cardiomyopathies in their end-stage phases.

Despite the broad and promising applications of these sequences as reported in the literature, certain challenges persist in their use. Specifically, the normal values for these sequences vary depending on the type of sequence and the specific MRI equipment employed. In our department, these sequences have been routinely used in clinical practice with a 1.5T MRI machine, for which the normal values have already been established and documented. With the recent installation of a new 3T MRI system, it is therefore necessary to determine the normal values of parametric sequences in healthy subjects to enable their use in routine clinical practice and for research purposes involving patients with various types of cardiomyopathies.

Inclusion criteria

• Healthy volunteers with a negative history of established cardiac disease
• 20-70 years old
• Acquisition of informed consent

Exclusion criteria

• Positive family history of known cardiomyopathies, sudden cardiac death
• Taking specific chronic therapy for diabetes and hypertension with ≥ 2 drugs and/or
• Cardio-vascular risk factors: obesity, hypertension on ≥ 2 drugs, smoking (>10 cigarettes/day)
• Competitive sports subjects or athletes (defined as >9 hours of sports activity/week)
• Pregnant women
• Claustrophobic subjects
• Other absolute contraindications to MRI
• Subjects with a relationship of direct/indirect subordination from the Radiology Unit, IRCCS - Azienda Ospedaliero Universitaria di Bologna Policlinico S. Orsola-Malpighi