Reference intervals for myocardial T1, T2, and extracellular volume in clinically normal dogs and cats at 3-Tesla magnetic resonance imaging: a single-center study.
Jul 2026· American Journal of Veterinary Research· pp.
1-7
· 0 citations· 33 references
Medicine
Abstract
Objective
To establish species-specific reference values for myocardial native T1, native T2, and extracellular volume fraction (ECV) in clinically normal dogs and cats using a 3-Tesla (3-T) cardiac MRI (CMRI) and to provide a description of image acquisition and analysis suitable for veterinary clinical and research applications.
Methods
Cardiac examinations were performed between 2015 and 2024 using a 3-T system with ECG gating under general anesthesia on clinically normal client-owned dogs and cats. Native T1 and T2 maps were acquired at the midventricular short-axis level using validated mapping sequences adapted from human CMRI protocols. Calculated ECV values were obtained from native and postcontrast T1 measurements in conjunction with Hct values. Reference intervals were determined using parametric methods and expressed as 95% prediction intervals with 90% CIs around the lower and upper reference limits.
Results
In dogs (n = 54), native T1, native T2, and ECV reference intervals (95% prediction intervals) were 1,057 to 1,152 ms, 42.0 to 60.9 ms, and 19.3% to 25.7%, respectively. In cats (n = 60), corresponding reference intervals were 1,066 to 1,172 ms, 34.2 to 61.6 ms, and 21.8% to 30.3%. Age was not a significant predictor of myocardial ECV in either species.
Conclusions
This study establishes clinically applicable reference values for myocardial T1, T2, and ECV in dogs and cats at 3 T and provides imaging methodology to facilitate reproducibility.
Clinical Relevance
Species-specific reference intervals established in this study enable objective quantification of myocardial composition and support clinical implementation of CMRI tissue characterization in dogs and cats.
BACKGROUND
Cardiac magnetic resonance (CMR) enables the quantitative characterization of myocardial tissue through parametric myocardial tissue mapping. It shows a strong correlation with invasive histologic techniques in assessing diffuse myocardial fibrosis using native T1 mapping and extracellular volume (ECV), as well as in assessing myocardial edema with T2 mapping. Pediatric applicability is currently limited by a lack of specific reference values for this population, with no recommendations available from the Society of Cardiac Magnetic Resonance.
OBJECTIVE
To determine reference values for global left ventricular native T1, T2 mapping, and extracellular volume fraction and to assess the influence of age, heart rate, body surface area, and sex on these parameters in children and adolescents.
MATERIALS AND METHODS
Data were retrospectively collected between 2018 and 2024. A total of 194 healthy children aged up to 17 years underwent CMR. The participants had a mean age of 12.6 (3.4) CI [12.1; 13.1] years (range 0.3-17), and 41% were female. A 1.5-T Siemens MAGNETOM Avanto Fit scanner was used. Native T1 mapping was performed at the base, mid-chamber, and apex of the left ventricle in the short-axis view at end-diastole using a MOLLI sequence, before and 15 min after the administration of a gadobutrol-based contrast agent. T2 mapping was performed before contrast administration at the base, mid-chamber, and apex of the left ventricle at end-diastole using a dark blood turbo spin echo sequence featuring a T2 preparation pulse and a balanced steady-state free precession (bSSFP). Linear regression models were employed to explore the relationships between native T1, ECV, and T2 mapping values and heart rate, age, and body surface area (BSA).
RESULTS
The results showed a mean global native T1 of 1004±37 ms, ECV of 25.9±3.6%, and T2 of 48.8±4 ms. T1 and ECV values were negatively correlated with age and BSA (P<0.001) and positively correlated with heart rate (P<0.001). In contrast, T2 values were negatively correlated with age (P<0.001) but not with heart rate (P=0.953 in the septum and P=0.445 in the free wall). Native T1 values were significantly higher in female patients than in males when analyzed separately for the interventricular septum and the left ventricular free wall (P=0.014 and P=0.001).
CONCLUSION
This study provides a median range of values in native T1, T2 mapping, and ECV in a pediatric population. The low number of participants under the age of 6 should be taken into account in the results of our study. Our findings corroborate that native T1 is influenced by both age and heart rate, while T2 is primarily affected by age alone. We observed higher native T1 values in females, highlighting the need for separate, sex-specific reference ranges. Therefore, age, heart rate, and sex should be considered in pediatric myocardial mapping.
Lucia Riaza-Martin, J. Escudero-Fernandez, Luis Riera-Soler et al.· Pediatric Radiology· 0 citations
Background: Quantitative myocardial T1 and T2 mapping is integral to cardiovascular magnetic resonance (CMR) imaging. Absolute myocardial relaxation times vary across imaging platforms due to system-specific technical factors. Consequently, mapping reference ranges are not transferable across platforms and require scanner-specific calibration. This study aimed to establish normal T1 and T2 reference intervals on a 1.5 Tesla (T) Siemens Aera system (Siemens, Erlangen, Germany) at Tygerberg Hospital.
Methods: Healthy adults were prospectively enrolled using strict inclusion criteria. Participants were required to undergo a normal clinical evaluation before qualifying for CMR and potential study inclusion. Final inclusion followed confirmation of normal cardiac structure and function, with no late gadolinium enhancement (LGE) on CMR. CMR imaging included balanced steady-state free precession (SSFP) cine sequences, shortened modified Look-Locker inversion recovery (shMOLLI) T1 mapping, and T2-prepared mapping sequences with a balanced SSFP readout. Analysis was performed using cvi42 software (Circle Cardiovascular Imaging, Canada) with manual contouring, and reference ranges were derived as mean ± 2 standard deviations (SD).
Results: A total of 76 participants met the inclusion criteria. Mean global native T1 was 998 ± 25.6 ms (reference interval 947–1 049 ms) and native T2 was 46.6 ± 1.8 ms (reference interval 43.0–50.1 ms).
Conclusion: This study established scanner-specific native T1 and T2 reference intervals for a South African population scanned on a 1.5T Siemens Aera system.
AIMS
Accurate age- and sex-specific T1 and T2 reference values are critical for differentiating myocardial pathologies, yet existing data are inconsistent due to methodological variability. This study proposes standardized T1 and T2 mapping protocols with clinically feasible breath-hold durations and reports site-, sequence-, age-, sex-, and segment-specific reference values.
METHODS AND RESULTS
This prospective, single-center study enrolled 183 healthy Caucasian subjects (median age 34 y [IQR 22, 50], range 11-70 y, 98 females) who underwent both global and AHA segment-based native T1 and T2 mapping at 3 T. T1 was assessed using Modified Look-Locker Inversion-Recovery sequence, MOLLI 5s(3s)3s, while T2 was performed using a gradient spin-echo (GraSE) protocol with echo-planar-imaging readout. Assessment of T1 and T2 relaxation times was highly reproducible, with low intra- and interobserver, scan-rescan, and test-retest variability. Mean global T1 was 1238 ± 28 ms, and median global T2 was 45.4 ms [44.3, 46.8]. T1 was significantly higher in women than in men (1245 ± 28 ms vs. 1230 ± 7 ms, P < 0.001), while T2 did not differ significantly (45.3 ms [44.2, 46.6] vs. 45.6 ± 2.2 ms, P = 0.453). Segmental analysis showed higher T1 and T2 values in the septum than in the lateral wall (P < 0.005). Subtle associations of age with T1 and T2 were observed.
CONCLUSION
This single-center study supports the use of sex- and segment-specific reference values for standardized T1-MOLLI and T2-GraSE mapping at 3 T to facilitate the characterization of myocardial pathologies, while age seems to be negligible.
H. Körperich, N. Shanmugarajah, Arnold Schneider et al.· Clinical Research in Cardiol...· 0 citations
Native T1 values in cardiac magnetic resonance (CMR) are influenced by acquisition sequence, physiological factors, and site-specific variability, complicating clinical interpretation. The absence of population-specific reference values further limits diagnostic accuracy. This study aimed to establish native T1 reference ranges in a Tunisian population, evaluate sex- and age-related differences using MOLLI 5(3)3 and SMART1Map sequences, and assess inter-site variability of MOLLI measurements across two centers using identical scanners and protocols. Ninety-four healthy volunteers were enrolled: 64 subjects (24 females, 40 males; 5–77 years) were scanned at Site 1 to establish reference values, and 30 subjects (20 females, 10 males; 19–62 years), frequency-matched by age to a subset of Site 1, were scanned at Site 2 to evaluate site-related variability. MOLLI-derived T1 values showed a significant negative association with age (β = –0.84 ms/year, p = 0.012), whereas SMART1Map-derived values were not associated with age (β = 0.30 ms/year, p = 0.556). SMART1Map consistently yielded higher T1 values than MOLLI (global mean ± SD: 1184 ± 70 ms vs. 1049 ± 55 ms; p < 0.001). Sex-related differences were minimal, with only a small apical difference observed for MOLLI (p = 0.023). Multi-center MOLLI measurements showed similar T1 distributions across sites, with minor differences observed at the mid-ventricular level. These findings provide the first Tunisian-specific native myocardial T1 reference values at 1.5 T, highlighting sequence-dependent differences, age-related effects for MOLLI, minimal sex-related influence, and overall inter-site consistency. These findings support the use of locally derived, sequence-specific reference ranges to improve clinical interpretation.
High-field cardiac magnetic resonance imaging (MRI) enables noninvasive assessment of myocardial tissue characteristics in anesthetized dogs; however, adenosine stress myocardial mapping at 3.0 T remains insufficiently characterized. This study evaluated stress–rest changes and level-dependent variation in quantitative myocardial mapping indices. Seven clinically asymptomatic dogs not receiving cardiac medications underwent 3.0 T cardiac MRI under general anesthesia in this prospective observational methodological study. Each dog completed two left ventricular myocardial mapping sessions (adenosine stress and rest) separated by ≥48 h. During stress, adenosine was infused at 140 μg/kg/min. T1 native, T1 post, T2, and extracellular volume fraction (ECV) were acquired at basal, mid, and apical short-axis levels. Stress–rest differences were tested with the Wilcoxon signed-rank test, and basal–mid–apical differences were assessed using generalized estimating equations (GEE) (p < 0.05). Under adenosine stress, global T1 native and T2 were 6.73 and 10.16% higher than at rest, whereas global T1 post and ECV did not change significantly. Level-wise analyses showed basal predominance for T1 native, a modest stress-only basal–mid difference for ECV, and lower basal T2 at rest. At 3.0 T, adenosine stress was associated with measurable increases in myocardial T1 native and T2 in anesthetized dogs, supporting further evaluation of protocol-specific, stress-associated mapping responses without relying solely on contrast-enhanced indices. Because mapping values varied across basal, mid, and apical levels, myocardial sampling level should be considered when interpreting or comparing canine stress–rest maps.
Establishing local reference ranges for native T1 in healthy myocardium is critical in cardiac magnetic resonance imaging (CMR) for the accurate detection of myocardial fibrosis and other tissue abnormalities. However, native T1 measurements vary widely and are sensitive to technical factors such as the magnetic field strength, static magnetic field (B0) and radiofrequency (B1) homogeneities, differences in MRI scanners across various vendors, imaging protocols, and specific acquisition parameters employed. These variabilities have consequently hindered the direct comparison of T1 values across different studies and centers. This review aims to evaluate the main technical challenges and methodological inconsistencies that impact the establishment of local native T1 reference ranges in CMR, and review proposals for mitigation, harmonization, and standardization strategies designed to enhance comparability across CMR platforms. A comprehensive literature search was conducted focusing on myocardial native T1 mapping using the modified Look-Locker inversion recovery (MOLLI) technique and its variants, as well as on alternative T1 mapping sequences like ShMOLLI, SASHA, SMART1Map, and SAPPHIRE. Reported native T1 values in healthy myocardium were found to be inconsistent across studies, driven by differences in the magnetic field strength, static magnetic field (B0), and radiofrequency (B1) homogeneities, and vendor-specific hardware and software configurations. Standardization of T1 mapping protocols, including standardized imaging parameters and vendor-specific reference adjustment, is therefore necessary to improve the comparability and reliability of myocardial T1 values across CMR centers. In addition, a robust quality assurance (QA) program and effective quality control (QC) measures are pivotal in ensuring the reliability and consistency of the measurements. Question How do technical factors and scanner-specific variabilities hinder the establishment of reliable local native T1 reference ranges for accurate myocardial tissue characterization? Findings Standardization of acquisition parameters, vendor-specific benchmarks, and robust quality assurance programs effectively minimize inter-scanner variability, ensuring reliable and comparable native myocardial T1 measurements across centers. Critical relevance statement This review identifies technical drivers of T1 variability and proposes a standardization framework, enabling clinicians to establish accurate local reference ranges and improve diagnostic comparability across diverse platforms in clinical radiology practice. Question How do technical factors and scanner-specific variabilities hinder the establishment of reliable local native T1 reference ranges for accurate myocardial tissue characterization? Findings Standardization of acquisition parameters, vendor-specific benchmarks, and robust quality assurance programs effectively minimize inter-scanner variability, ensuring reliable and comparable native myocardial T1 measurements across centers. Critical relevance statement This review identifies technical drivers of T1 variability and proposes a standardization framework, enabling clinicians to establish accurate local reference ranges and improve diagnostic comparability across diverse platforms in clinical radiology practice.
Maheran Che Ha, K. A. Sayuti, Y. Mohammed et al.· Insights into Imaging· 0 citations