mDIXON-Quant technique diagnostic accuracy for assessing bone mineral density in male adult population

BACKGROUND

To investigate the diagnostic efficacy of mDIXON-Quant technique for prediction of bone loss in male adults.

METHODS

One hundred thirty-eight male adults were divided into normal, osteopenia, and osteoporosis groups based on DXA and QCT for the lumbar spine. Differences in mDIXON-Quant parameters [fat fraction (FF) and T2^* value] among three groups, as well as the correlation of mDIXON-Quant parameters and bone mineral density (BMD) were analyzed. The areas under the curves (AUCs) for mDIXON-Quant parameters for prediction of low bone mass were calculated.

RESULTS

According to DXA standard, FF and T2^* value were significantly increased in osteoporosis group compared with normal group (P = 0.012 and P < 0.001). According to QCT standard, FF was significantly increased in osteopenia and osteoporosis groups compared with normal group (both P < 0.001). T2^* values were significantly different among three groups (all P < 0.05). After correction for age and body mass index, FF was negatively correlated with areal BMD and volumetric BMD (r = -0.205 and -0.604, respectively; both P < 0.05), and so was T2^* value (r = -0.324 and -0.444, respectively; both P < 0.05). The AUCs for predicting low bone mass according to DXA and QCT standards were 0.642 and 0.898 for FF, 0.648 and 0.740 for T2^* value, and 0.677 and 0.920 for both combined, respectively.

CONCLUSIONS

FF combined with T2^* value has a better diagnostic efficacy than FF or T2^* value alone in prediction of low bone mass in male adults, which is expected to be a promising MRI method for the screening of bone quality.

TRIAL REGISTRATION

ChiCTR1900024511 (Registered 13-07-2019).

[Quantitative analysis of non-alcoholic fatty liver disease based on MRI proton density fat fraction in the coastal region of Qingdao]

Objective: To explore the clinical application value of MRI-PDFF on different liver segments for the evaluation of non-alcoholic fatty liver disease (NAFLD). Methods: 178 volunteers from March 2019 to February 2020 were included. PDFF values ​​of all nine segments of the liver were measured using CSE3.0T MRI scan. The obtained average value was used to represent the average liver fat content. PDFF values of each or combined liver segment were equally compared with the average value to observe the representativeness of fat content. Receiver operating characteristic curve was used to analyze the diagnostic performance of each liver segment, and the Youden index was used to calculate the cutoff value. Paired-sample t-test or non-parametric Kruskal-Wallis test were used to compare measurement data among groups. Results: 178 volunteers average liver fat content ranged from 0.89% to 42.61% with MRI-PDFF, and 71.35% (127/178) of the volunteers had PDFF > 5%. There was no significant difference between SIII, SIVb, SV, and SVIII liver segments when compared with the average value (P > 0.05). PDFF values ​​of SI, SII, and SIV a liver segments were all lower than the average value, while the PDFF values ​​of SVI and SVII liver segments were all higher than the average value (P ​​< 0.05). MRI-PDFF sensitivity value for diagnosing liver steatosis of nine liver segments was 85.8% ~ 94.5%, and the specificity was higher than 96.0%. Among them, the SV liver segment had the highest sensitivity (94.5%), and the corresponding optimal diagnostic threshold value was 5.13%. Compared with single and combined liver segment, the PDFF value of SII, SV, SVI combined liver segment had the highest diagnostic performance for fatty liver, with the sensitivity and specificity of 96.9%, and 100%, respectively, and the corresponding optimal diagnostic threshold value was 5.17%. Conclusion: Compared with single and other combined liver segments, MRI-PDFF values of SII, SV, and SVI combined liver segments have higher sensitivity and specificity for the diagnosis of NAFLD, and it can be used as the first choice for the determination of liver fat content with MRI.

Two-point Dixon fat-water swapping artifact: lesion mimicker at musculoskeletal T2-weighted MRI

Fat-water swapping is an artifact specific to chemical shift encoded MRI and so-called Dixon methods. It is more frequent using the 2-point than the multi-point (> 2) Dixon method. Actually, fat-water swapping on the 2-point Dixon sequences partly triggered the development of the multi-point techniques. Fat-water swapping occurs on post-processing calculated fat- and water-only images, but not on the directly acquired in-phase and out-of-phase source images. It originates from a natural ambiguity between fat and water peaks that may cause inverted calculation between fat- and water-only voxels. Fat-water swapping artifact over large areas encompassing multiple tissues can easily be recognized, but it may be confusing when the calculation errors are limited to a single anatomic structure or a small area, especially on T2-weighted images. We report four cases with 2-point Dixon fat-water swapping artifacts mimicking musculoskeletal lesions at T2-weighted MRI and propose hints to avoid misinterpretation.