Simultaneous proton density fat‐fraction and imaging with water‐specific T₁ mapping (PROFIT₁): application in liver

Abstract

To describe and validate a simultaneous proton density fat-fraction (PDFF) imaging and water-specific T 1 mapping (T 1(Water)) approach for the liver (PROFIT 1) with R * 2 mapping and low sensitivity to B + 1 calibration or inhomogeneity. Methods: A multiecho gradient-echo sequence, with and without saturation preparation, was designed for simultaneous imaging of liver PDFF, R * 2 , and T 1(Water) (three slices in ~13 seconds). Chemical-shift-encoded MRI processing yielded fat-water separated images and R * 2 maps. T 1(Water) calculation utilized saturation and nonsaturationrecovery water-separated images. Several variable flip angle schemes across k-space (increasing flip angles in sequential RF pulses) were evaluated for minimization of T 1 weighting, to reduce the B + 1 dependence of T 1(Water) and PDFF (reduced flip angle dependence). T 1(Water) accuracy was validated in mixed fat-water phantoms, with various PDFF and T 1 values (3T). In vivo application was illustrated in five volunteers and five patients with nonalcoholic fatty liver disease (PDFF, T 1(Water) , R * 2). Results: A sin 3 (θ) flip angle pattern (0 < θ < π/2 over k-space) yielded the largest PROFIT 1 signal yield with negligible B + 1 dependence for both T 1(Water) and PDFF. Mixed fat-water phantom experiments illustrated excellent agreement between PROFIT 1 and gold-standard spectroscopic evaluation of PDFF and T 1(Water) (<1% T 1 error). In vivo PDFF, T 1(Water) , and R * 2 maps illustrated independence of the PROFIT 1 values from B + 1 inhomogeneity and significant differences between volunteers and patients with nonalcoholic fatty liver disease for T 1(Water) (927 ± 56 ms vs. 1033 ± 23 ms; P < .05) and PDFF (2.0% ± 0.8% vs. 13.4% ± 5.0%, P < .05). R * 2 was similar between groups. Conclusion: The PROFIT 1 pulse sequence provides fast simultaneous quantification of PDFF, T 1(Water) , and R * 2 with minimal sensitivity to B + 1 miscalibration or inhomogeneity.

Confounder‐corrected T1 mapping in the liver through simultaneous estimation of T1, PDFF, R2*, and B1+ in a single breath‐hold acquisition

“…5 More recently, Thompson et al proposed a saturation recovery based T 1 mapping method in the liver similar to the cardiac SMART 1 Map application. 58 However, the duration of these T 1 mapping methods typically limit the acquisition to just a few slices per breath-hold, making volumetric T 1 mapping of the liver infeasible.…”

“…These methods, and others like them (e.g., saturation recovery single‐shot acquisition—SASHA), enable T 1 mapping to be used clinically and are used widely today 5 . More recently, Thompson et al proposed a saturation recovery based T 1 mapping method in the liver similar to the cardiac SMART 1 Map application 58 . However, the duration of these T 1 mapping methods typically limit the acquisition to just a few slices per breath‐hold, making volumetric T 1 mapping of the liver infeasible.…”

Rationale and design of IMPACT-women: a randomised controlled trial of the effect of time-restricted eating, healthy eating and reduced sedentary behaviour on metabolic health during chemotherapy for early-stage breast cancer

“…3T MRI (Siemens Prisma at both sites) will be used to quantify all AT volumes including the primary outcome of visceral AT. We will use standard chemical shift-encoding MRI and custom PROFIT1 ( 30 ) pulse sequences for image acquisition without contrast agents. Abdominal AT (both visceral and subcutaneous) and liver AT fraction will be captured from three axial slices prescribed at the centre of the third lumbar vertebra and the middle of liver, respectively.…”

Implementation of weekday time‐restricted eating to improve metabolic health in breast cancer survivors with overweight/obesity

“…MRI scans took place on a 3-T system (PRISMA; Siemens Healthineers, Erlangen, Germany). A liver-specific chemical-shift-encoded approach [20] was used to quantify the proton-density adipose tissue (AT) fraction in three axial sections at the largest cross section of the liver. Average AT fraction for all pixels within the liver are reported (6 mm section thickness, 1.4 Â 1.4 in-plane resolution, 13-second breath-hold acquisition).…”