Citations

BackgroundLarge‐scale normative studies of pancreatic stiffness and potential influences have yet to be pursued via magnetic resonance elastography (MRE).PurposeTo determine normative MRE‐based pancreatic stiffness values and to examine related influential factors.Study TypeProspective.SubjectsIn all, 361 volunteers (men, 199; women, 162) with a median age of 54.0 years and a median body mass index (BMI) of 22.86 kg/m2 were prospectively recruited. Those with no histories of smoking, alcohol abuse, and diabetes mellitus (DM) were grouped as healthy volunteers, designating all others as positive controls.Field Strength/SequenceEach volunteer underwent 3.0T pancreatic MRI at a frequency of 40 Hz.AssessmentPancreatic stiffness values, pancreatic width and volume, waist circumference, and wave distance were measured in all subjects.Statistical TestsMultiple linear regression analyses were performed to determine variables that influence MRE‐determined stiffness.ResultsThe mean pancreatic stiffness in all volunteers was 1.20 ± 0.16 kPa. Stiffness levels in positive control volunteers proved significantly greater than levels in healthy volunteers (1.29 ± 0.17 kPa vs. 1.14 ± 0.13 kPa; P < 0.001). In multiple linear regression analysis, sex (P = 0.004), BMI (P < 0.001), pancreatic width (P = 0.005), smoking (P < 0.001), alcohol abuse (P < 0.001), and DM (P = 0.001) emerged as significant independent factors impacting pancreatic stiffness. Smoking, alcohol abuse, DM, and wide pancreas were associated with greater pancreatic stiffness (coefficients = 0.202, 0.183, 0.149, and 0.160, respectively), while reduced pancreatic stiffness corresponded with female sex and larger BMI (coefficient = −0.155 and −0.192, respectively).Data ConclusionMRE‐based pancreatic stiffness values are impacted by sex, BMI, pancreatic width, smoking, alcohol abuse, and DM. Reference values are essential for future clinical studies.Level of Evidence: 1Technical Efficacy: Stage 2J. Magn. Reson. Imaging 2020;52:448–458.

MRS provides a valuable tool for the non‐invasive detection of brain γ‐aminobutyric acid (GABA) in vivo. GABAergic dysfunction has been observed in the aging cerebellum. The study of cerebellar GABA changes is of considerable interest in understanding certain age‐related motor disorders. However, little is known about the reproducibility of GABA MRS in an aged population. Therefore, this study aimed to explore the feasibility and reproducibility of GABA MRS in the aged cerebellum at 3.0 T and to examine the effect of differing tissue composition on GABA measurements. MRI and 1H MRS examinations were performed on 10 healthy elderly volunteers (mean age, 75.2 ± 6.5 years) using a 3.0‐T Siemens Tim Trio scanner. Among them, five subjects were scanned twice to assess the short‐term reproducibility. The MEGA‐PRESS (Mescher–Garwood point‐resolved spectroscopy) J‐editing sequence was used for GABA detection in two volumes of interest (VOIs) in the left and right cerebellar dentate. MRS data processing and quantification were performed with LCModel 6.3‐0L using two separate basis sets, generated from density matrix simulations using published values for chemical shifts and J couplings. Raw metabolite levels from LCModel outputs were corrected for cerebrospinal fluid contamination and relaxation. GABA‐edited spectra yielded robust and stable GABA measurements with averaged intra‐individual coefficients of variation for corrected GABA+ between 4.0 ± 2.8% and 13.4 ± 6.3%, and inter‐individual coefficients of variation between 12.6% and 24.2%. In addition, there was a significant correlation between GABA+ obtained with the two LCModel basis sets. Overall, our results demonstrated the feasibility and reproducibility of cerebellar GABA‐edited MRS at 3.0 T in an elderly population. This information might be helpful for studies using this technique to study GABA changes in normal or diseased aging brain, e.g. for power calculations and the interpretation of longitudinal observations. Copyright © 2015 John Wiley & Sons, Ltd.