Clinical application and technical considerations of T  1 & T  2(*) mapping in cardiac, liver, and renal imaging

Abstract

Pathological tissue alterations due to disease processes such as fibrosis, edema and infiltrative disease can be non-invasively visualized and quantified by MRI using T and T relaxation properties. Pixel-wise mapping of T and T image sequences enable direct quantification of T, T(*), and extracellular volume values of the target organ of interest. Tissue characterization based on T and T(*) mapping is currently making the transition from a research tool to a clinical modality, as clinical usefulness has been established for several diseases such as myocarditis, amyloidosis, Anderson-Fabry and iron deposition. Other potential clinical applications besides the heart include, quantification of steatosis, cirrhosis, hepatic siderosis and renal fibrosis. Here, we provide an overview of potential clinical applications of T andT(*) mapping for imaging of cardiac, liver and renal disease. Furthermore, we give an overview of important technical considerations necessary for clinical implementation of quantitative parametric imaging, involving data acquisition, data analysis, quality assessment, and interpretation. In order to achieve clinical implementation of these techniques, standardization of T and T(*) mapping methodology and validation of impact on clinical decision making is needed.

Native T1 Mapping Magnetic Resonance Imaging as a Quantitative Biomarker for Characterization of the Extracellular Matrix in a Rabbit Hepatic Cancer Model

“…Higher native T1 values are primarily attributable to an increase in interstitial space, such as collagen, or the presence of edema [ 29 ]. In addition, other factors were shown to influence T1 relaxation such as inflammation, iron concentration, and steatosis, with higher T1 relaxation times in inflammation being primarily associated with interstitial edema [ 34 , 35 , 36 ]. In our study, we measured prolonged T1 times in the tumor center with decreasing values towards the peritumoral region and the shortest T1 relaxation times in the liver parenchyma.…”

“…However, there was no histopathological evidence of excessive scarring. Finally, as already mentioned above, T1 relaxation times are influenced by other factors such as iron concentration and steatosis [ 34 , 35 , 36 ]. While liver steatosis is unlikely in the young rabbits used in our study, a more accurate quantification of T1 relaxation times would probably be possible by simultaneous measurement of liver and tumor iron concentrations.…”

Recent advances in renal imaging

“…Several MRI methods can also be used to evaluate renal fibrosis, and efforts are underway to standardize these techniques 82 . Similar to ultrasound elastography, MR elastography can be used to measure kidney stiffness as an indicator of fibrosis.…”

Rapid 2D variable flip angle method for accurate and precise T1 measurements over a wide range of T1 values

“…Quantitative T 1 mapping may help to non‐invasively characterize and discriminate biological tissues. This is of interest for various organs comprising the heart, 1,2 liver and kidney, 2 and brain 3 . Methods based on 3D gradient echo (GRE) acquisitions at either multiple flip angles (FAs) or multiple repetition times ( T R ) are used for T 1 mapping 4 .…”