Application of MRI Water-Fat Separation Technology in Patients with Multiple Myeloma / 中国实验血液学杂志

OBJECTIVE@#To explore the clinical significance of magnetic resonance imaging water-fat separation (Dixon) technique in patients with multiple myeloma.@*METHODS@#A total of 41 newly diagnosed patients with multiple myeloma who underwent Dixon in The Affiliated Hospital of Qingdao University from April 2019 to April 2021 were included in this study. Patients were divided into observation group and control group according to whether Dixon performance was normal or not. The differences of clinical data and fat fraction (FF) between the two groups were compared. The correlation between FF and clinical data, disease stages and differences before and after treatment were also compared. The receiver operator characteristic curve of patients was drawn to analyze the diagnostic value of FF combined with serum alkaline phosphatase for bone destruction in patients with multiple myeloma.@*RESULTS@#Among the 41 patients, there were 12 cases in the control group and 29 cases in the observation group. There was no significant difference in age and sex between the two groups. In the observation group, β2-microglobulin concentration and M protein were significantly higher than those in the control group, while serum alkaline phosphatase and FF were lower (P<0.05). In all 41 patients included in the study, there was a significant negative correlation between FF value and β2-microglobulin concentration (r=-0.57), and a significant positive correlation between FF value and serum alkaline phosphatase (r=0.31). After treatment, FF value increased, while myeloma cell percentage, β2-microglobulin concentration and M protein decreased in 11 patients who completed 4 cycles of chemotherapy, and the differences before and after treatment were statistically significant (P<0.05). The value of serum alkaline phosphatase combined with FF value in predicting bone destruction is higher than that of FF value or serum alkaline phosphatase alone.@*CONCLUSION@#Dixon's different imaging manifestations can reflect the severity of the disease. FF value is correlated with clinical examination results and R-ISS staging, and there is a significant difference before and after treatment. Serum alkaline phosphatase combined with FF value is better than two indicators alone in predicting bone destruction.

Effect of hepatic fibrosis on proton density fat fraction based on histogram analysis in evaluating hepatic steatosis: an experimental study / 中华放射学杂志

Objective:To explore the value of proton density fat fraction(PDFF) based on histogram analysis for quantification hepatic steatosis and fibrosis in rabbit model and the interference of hepatic fibrosis to the evaluation of hepatic steatosis with PDFF.Methods:From March to November 2020, 135 New Zealand white rabbits were randomly divided into control group ( n=30) and experimental group ( n=105) using a random number table. The volume ratio of CCl 4 and olive oil was 1∶1 to prepare 50% CCl 4 oil solution, and experimental rabbits were subcutaneously injected with the oil solution. An equal dose of normal saline was subcutaneously injected for control group rabbits. At the end of the 4 th, 8 th, and 12 th week, 35 in the experimental group and 10 rabbits in the control group were randomly selected to conduct the mDixon-Quant scanning, and histogram analysis of PDFF was analyzed including volume, mean, median, standard deviation, 25 th, 50 th, 75 th, 90 th quantile, skewness, kurtosis, entropy and inhomogeneity. After the examination, the rabbits were sacrificed and the liver percentage of steatosis (PSH) and fibrosis (POF) were recorded by semi-quantitative analysis. Spearman correlation analysis was used to correlate PDFF with PSH and POF. Multiple linear regression analysis was used to determine independent PDFF histogram parameters for evaluating PSH and POF. A receiver operator characteristic (ROC) curve was used to assess the diagnostic accuracy of PDFF for discriminating mild from moderate-severe hepatic steatosis and mild from moderate-severe hepatic fibrosis with median of PSH or POF for dichotomy, and DeLong test was used to compare the area under the curve (AUC). With the correction of hepatic fibrosis, correlation coefficient and AUC were compared of PDFF for discrimination mild from moderate-severe hepatic steatosis. Results:The PDFF mean, median, standard deviation, 75 th, 90 th showed correlation with PSH ( r=0.558, 0.522, 0.319, 0.723, 0.646, -0.589, all P<0.05). The entropy and 75 th were independent parameters for evaluating PSH (β=2.347, -5.960, P=0.018, 0.001). The PDFF 75 th was the optimal parameter for discriminating mild from moderate-severe hepatic steatosis with AUC=0.915 ( P=0.001). The PDFF volume, mean, median, standard deviation, 75 th, 90 th, entropy showed correlation with POF ( r=0.355, 0.393, 0.376, 0.298, 0.485, 0.426, -0.681, all P<0.05). The entropy, standard deviation and volume (β=-11.041, 1.356, 0.190, P=0.001, 0.026, 0.016) were independent parameters for evaluation of hepatic fibrosis, and the entropy was the optimal parameter for hepatic fibrosis (AUC=0.771, P=0.001). The correlation between PSH and PDFF 75 th was less pronounced when fibrosis was present ( r=0.512, P=0.001) than when fibrosis was absent ( r=0.751, P=0.002). The PDFF 75 th showed a significant difference in discriminating mild hepatic steatosis from moderate-severe hepatic steatosis after correction of POF (AUC=0.895, 0.950, Z=2.970, P=0.025). Conclusions:PDFF based on histogram analysis provided a noninvasive, accurate estimation of quantification for hepatic steatosis and fibrosis. Hepatic fibrosis reduced the correlation between hepatic steatosis and PDFF and the presence of hepatic fibrosis can confound the quantification of hepatic steatosis with PDFF.

Value of magnetic resonance imaging-proton density fat fraction and FibroScan in quantitative evaluation of liver fat content in patients with chronic hepatitis B / 临床肝胆病杂志

Objective To investigate the value of magnetic resonance imaging-proton density fat fraction (MRI-PDFF) and FibroScan in the quantitative evaluation of liver fat content in patients with chronic hepatitis B (CHB). Methods A total of 96 patients with CHB who were hospitalized in Department of Hepatology, The Second Clinical Medical College of Guangzhou University of Chinese Medicine, from February 2017 to July 2020 were enrolled, and all patients were diagnosed based on liver pathological examination. MRI-PDFF and FibroScan were performed before surgery. According to the results of liver biopsy, the patients were divided into non-fatty liver disease group with 44 patients, mild fatty liver disease group with 33 patients, and moderate-to-severe fatty liver disease group with 19 patients. A one-way analysis of variance was used for comparison of normally distributed continuous data between multiple groups, and the least significant difference t -test was used for further comparison between two groups; the Kruskal-Wallis H test was used for comparison of non-normally distributed continuous data between multiple groups, and the Mann-Whitney U test was used for further comparison between two groups; Bonferroni correction was also performed. The receiver operating characteristic (ROC) curve was plotted to analyze the area under the ROC curve (AUC) of hepatic fat fraction (HFF) and controllable attenuation parameters (CAP) in the diagnosis of fatty liver disease and obtain their sensitivities, specificities, and optimal cut-off values. The intraclass correlation coefficient was used to investigate the consistency of MRI-PDFF data. Results The moderate-to-severe fatty liver disease group had a significant increase in MRI-PDFF HFF compared with the non-fatty liver disease group and the mild fatty liver disease group (all P < 0.05), and the mild fatty liver disease group had a significant increase in MRI-PDFF HFF compared with the non-fatty liver disease group( P < 0.05). The moderate-to-severe fatty liver disease group had a significant increase in FibroScan CAP compared with the non-fatty liver disease group and the mild fatty liver disease group (all P < 0.05), and the mild fatty liver disease group had a significant increase in FibroScan CAP compared with the non-fatty liver disease group ( P < 0.05). In the diagnosis of mild fatty liver disease, MRI-PDFF HFF had an AUC of 0.901 ( P < 0.001), a sensitivity of 90.9%, and a specificity of 82.7% at the optimal cut-off value of 5.1%, and in the diagnosis of moderate-to-severe fatty liver disease, MRI-PDFF HFF had an AUC of 0.972 ( P < 0.001), a sensitivity of 96.1%, and a specificity of 89.5% at the optimal cut-off value of 9.7%. In the diagnosis of mild fatty liver disease, FibroScan CAP had an AUC of 0.829 ( P < 0.001), a sensitivity of 77.3%, and a specificity of 78.8% at the optimal cut-off value of 258.5 dB/m, and in the diagnosis of moderate-to-severe fatty liver disease, FibroScan CAP had an AUC of 0.830 ( P < 0.001), a sensitivity of 76.6%, and a specificity of 78.9% at the optimal cut-off value of 285.5 dB/m. Conclusion Both MRI-PDFF and FibroScan can objectively evaluate the degree of fatty liver disease in patients with CHB. MRI-PDFF HFF and FibroScan CAP can be used as noninvasive markers for the quantitative analysis of CHB with hepatic steatosis, and MRI-PDFF HFF tends to have higher diagnostic efficiency.

Diagnostic Value of mDIXON Quant MRI for Vertebral Metastasis / 肿瘤防治研究

Objective To evaluate the diagnostic efficacy of mDIXON Quant for vertebral metastasis. Methods We retrospectively analyzed MRI images of 152 patients with clinically diagnosed malignant tumors and vertebral metastases. Scanning sequence included T1WI, STIR, mDIXON Quant and enhanced T1WI. We compared the diagnostic efficiency between T1WI and FF images for vertebral metastases. FF values between normal vertebral body and vertebral metastases were quantitatively compared, and the diagnostic efficacy of FF value was evaluated by ROC curve. Results The sensitivity, false positive rate, false negative rate, negative predictive value and accuracy of FF images in the diagnosis of vertebral metastases were all higher than those of T1WI images. The FF value of vertebral metastasis was significantly lower than that of normal vertebral body (Z=-21.792, P < 0.05), and the area under ROC curve was 0.987 and the cutoff value was 9.87%. The diagnostic sensitivity and specificity of vertebral metastasis were 99.6% and 92.0%. Conclusion mDIXON Quant can quantitatively determine the fat content of vertebral metastasis and has a high diagnostic efficiency for vertebral metastases.

Magnetic resonance imaging-proton density fat fraction: A potential surrogate endpoint for nonalcoholic steatohepatitis clinical trials / 临床肝胆病杂志

Magnetic resonance imaging-proton density fat fraction (MRI-PDFF) is an imaging method that uses magnetic resonance technology to perform objective, quantitative, and noninvasive assessment of fat in the whole liver. This article mainly analyzes the correlation between MRI-PDFF value and the “gold index” nonalcoholic steatohepatitis (NASH) liver histological evaluation and explores its advantages and disadvantages as a noninvasive evaluation index for NASH clinical trials. Current studies have shown that MRI-PDFF, as an emerging noninvasive technique, is suitable for quantifying liver fat content and evaluating the degree of hepatic steatosis, but it cannot replace liver biopsy as a tool for the diagnosis of NASH. Meanwhile, the relative reduction in MRI-PDFF after drug intervention is not only highly correlated with the improvement of fat deposition, but also correlated with the improvement of inflammation and ballooning degeneration, and MRI-PDFF can predict the overall improvement of liver histology to a certain extent. Therefore, MRI-PDFF is considered a potential surrogate endpoint for NASH clinical trials.

Simultaneous Estimation of the Fat Fraction and R₂* Via T₂*-Corrected 6-Echo Dixon Volumetric Interpolated Breath-hold Examination Imaging for Osteopenia and Osteoporosis Detection: Correlations with Sex, Age, and Menopause

OBJECTIVE: To investigate the relationships of T2 *-corrected 6-echo Dixon volumetric interpolated breath-hold examination (VIBE) imaging-based fat fraction (FF) and R2 * values with bone mineral density (BMD); determine their associations with sex, age, and menopause; and evaluate the diagnostic performance of the FF and R2 * for predicting osteopenia and osteoporosis. MATERIALS AND METHODS: This study included 153 subjects who had undergone magnetic resonance (MR) imaging, including MR spectroscopy (MRS) and T2 *-corrected 6-echo Dixon VIBE imaging. The FF and R2 * were measured at the L4 vertebra. The male and female groups were divided into two subgroups according to age or menopause. Lin's concordance and Pearson's correlation coefficients, Bland-Altman 95% limits of agreement, and the area under the curve (AUC) were calculated. RESULTS: The correlation between the spectroscopic and 6-echo Dixon VIBE imaging-based FF values was statistically significant for both readers (pc = 0.940 [reader 1], 0.908 [reader 2]; both p < 0.001). A small measurement bias was observed for the MRS-based FF for both readers (mean difference = −0.3% [reader 1], 0.1% [reader 2]). We found a moderate negative correlation between BMD and the FF (r = −0.411 [reader 1], −0.436 [reader 2]; both p <0.001) with younger men and premenopausal women showing higher correlations. R2 * and BMD were more significantly correlated in women than in men, and the highest correlation was observed in postmenopausal women (r = 0.626 [reader 1], 0.644 [reader 2]; both p < 0.001). For predicting osteopenia and osteoporosis, the FF had a higher AUC in men and R2 * had a higher AUC in women. The AUC for predicting osteoporosis was highest with a combination of the FF and R2 * in postmenopausal women (AUC = 0.872 [reader 1], 0.867 [reader 2]; both p < 0.001). CONCLUSION: The FF and R2 * measured using T2 *-corrected 6-echo Dixon VIBE imaging can serve as predictors of osteopenia and osteoporosis. R2 * might be useful for predicting osteoporosis, especially in postmenopausal women.

Comparison Thigh Skeletal Muscles between Snowboarding Halfpipe Athletes and Healthy Volunteers Using Quantitative Multi-Parameter Magnetic Resonance Imaging at Rest / 中华医学杂志(英文版)

<p><b>Background</b>Magnetic resonance (MR) imaging provides a unique, noninvasive diagnostic platform to quantify the physiological and biochemical variables of skeletal muscle at rest. This study was to investigate the difference in thigh skeletal muscles between snowboarding halfpipe athletes and healthy volunteers via multiparametric MR imaging.</p><p><b>Methods</b>A comparative study was conducted between 12 healthy volunteers and 14 snowboarding halfpipe athletes. MR scanning targeted the left leg at the level of the proximal thigh on a 3.0T MR system. The measured parameters compared between the two groups included T1, T2, T2* relaxation times, fat fraction (FF), and cross-sectional area (CSA) of the quadriceps femoris and the hamstring muscles. Statistical analysis was carried out using independent sample t-test. Interrater reliability was also assessed with intraclass correlation coefficients (ICCs).</p><p><b>Results</b>It was statistically equivalent between two groups in age, body mass index, thigh circumference, calf circumference, systolic blood pressure, and resting heart rate (all P > 0.05). However, the T1 and T2 values of the hamstring muscles in the athlete group were found to be significantly shorter than those in control group (T1: 1063.3 ± 24.1 ms vs. 1112.0 ± 38.2 ms in biceps femoris, 1050.4 ± 31.2 ms vs. 1095.0 ± 39.5 ms in semitendinosus, 1053.1 ± 31.7 ms vs. 1118.4 ± 40.0 ms in semimembranosus, respectively; T2: 33.4 ± 0.7 ms vs. 36.1 ± 1.9 ms in biceps femoris, 34.6 ± 2.0 ms vs. 37.0 ± 1.9 ms in semitendinosus, 36.9 ± 1.5 ms vs. 38.9 ± 2.4 ms in semimembranosus, respectively; all P < 0.05) although T2* relaxation time was detected with no significant difference. The FF of the hamstring muscles was obviously less than the control group (5.5 ± 1.9% vs. 10.7 ± 4.7%, P < 0.001). In addition, the quadriceps' CSA in the athlete group was substantially larger than the control group (8039.0 ± 1072.3 vs. 6258.2 ± 852.0 mm, P < 0.001). Interrater reliability was excellent (ICC: 0.758-0.994).</p><p><b>Conclusion</b>Multiple MR imaging parameters indicated significant differences between snowboarding halfpipe athletes and healthy volunteers in the thigh skeletal muscles.</p>

The value of quantitative diagnosis and grading of steatosis of nonalcoholic fatty liver disease by hydrogen proton MR spectroscopy and multi-echo Dixon technique / 中华放射学杂志

Objective To investigate the value of hydrogen proton MR spectroscopy (1H-MRS) and Dixon sequence for the quantitative diagnosis and classification of steatosis in patients with non-alcoholic fatty liver disease (NAFLD). Methods Sixty seven patients with NAFLD confirmed by liver biopsy were prospectively collected from October 2015 to May 2017 in Hangzhou Normal University Hospital. All patients underwent 1H-MRS and Dixon sequence scan within 7 days after liver biopsy, 1H-MRS-based hydrogen proton density fraction (MRS-PDFF) and Dixon-based hydrogen proton density fraction (MRI-PDFF) were obtained. Fat grading based on the fat percentage obtained from liver biopsy. Pearson correlation analysis was performed to analyze the correlation among pathological steatosis and MRS-PDFF, MRI-PDFF. One-way ANOVA analysis was performed to compare the difference of PDFF between patients with different degrees of severity of fatty liver. And the ROC curve analysis was performed to generate the thresholds of MRS-PDFF and MRI-PDFF for determining the presence of fatty liver. Results The steatosis grade of pathological biopsy showed grade S1 in 36 cases, grade S2 in 16 cases, grade S3 in 15 cases, the MRS-PDFF values of S1, S2 and S3 patients were (8.25 ± 4.32)％, (15.67 ± 4.54)％, (23.46 ± 5.82)％and the MRI-PDFF values were (6.31 ± 2.94)％, (15.42 ± 5.07)％, (24.47 ± 6.31)％. Statistically significant differences were observed among them (P<0.01). Both MRS-PDFF and MRI-PDFF were positively correlated with histological fat percentage (r values were 0.840 and 0.892,all P<0.01), there was also a correlation between MRS-PDFF and MRI-PDFF (r=0.930, P<0.01). Area under ROC curve of MRS-PDFF and MRI-PDFF for differential diagnosis of grade S1 steatosis were 0.955 and 0.976, and area under ROC curve for differential diagnosis of grade S3 steatosis were 0.972 and 0.978. Conclusion 1H-MRS and Dixon sequces have high value in liver fat content detection and classification of patients with NAFLD, and both have similar diagnostic efficacy.

Semi-quantitative analysis of hepatic fat in MR using Dixon technique and its clinical significance / 实用放射学杂志

Objective To investigate the correlation between hepatic fat fraction(HFF)and some clinical indicators by measuring HFF and summarize its clinical significance.Methods A total of 95 patients were included in this study.MR data were acquired with Dixon technique,and the HFF of liver were measured.According to the HFF,all patients were divided into high-fat group and low-fat group.Subcutaneous fat area(SA),visceral fat area(VA)and total fat area(TA)were also measured.The age of patients,blood pressure, fasting blood glucose(FPG),total cholesterol (TC),triglyceride (TG),low density cholesterol (LDL-c)and high density cholesterol (HDL-c) were recorded and the body mass index(BMI)was calculated.Results The levels of FPG,TG,LDL-c,systolic blood pressure,diastolic blood pressure,BMI,VA,TA and visceral fat percentage (VFP)in high-fat group were significantly higher than those in low-fat group (P<0.05), while the abdominal subcutaneous fat percentage (SFP)was significantly lower than that in low-fat group (P<0.05).HFF was positively correlated with FPG,TG,LDL-c,VA,TA,VFP,age and BMI (r=0.354,0.370,0.415,0.299,0.285,0.238,0.203,0.221,respectively;P<0.05).Conclusion Semi-quantitative analysis of hepatic fat using MR Dixon technique can reflect the degree of hepatic fatty infiltration, and can be used as a quantitative indicator for early diagnosis and treatment evaluation of nonalcoholic fatty liver disease.

The diagnostic application of fat quantification in the primary osteoporosis / 实用放射学杂志

Objective To investigate the change rules of the lumbar vertebral bone marrow fat fraction(FF)and T2* values at different bone mineral density(BMD)groups,and their relevances and the applications on the diagnosis of the primary osteoporosis. Methods The patients who underwent the dual energy X-ray absorptiometry(DXA)and the routine lumbar MRI scan,mDIXON-Quant scan were collected,and the BMD,T-score,FF and T2* values of L1-L4 were measured.According to the T-score,the vertebral bodies were divided into the normal group,the osteopenia group and the osteoporosis group.The differences of the FF,T2* values and BMD between each group were analyzed by one-way analysis of variance,and their correlations with BMD were analyzed by Pearson correlation,the diagnostic effects of them were evaluated by receiver operating characteristic curve(ROC curve).Results The differences of the FF ,T2 * values and BMD among the three groups were statistically significant (P < 0 .05) .The correlations of the FF and T2 * values with BMD were negative (r = - 0 .628 ,P < 0 .05 and r = - 0 .468 ,P < 0 .05 ,respectively) .The area under curve (AUC) of the FF and T2 * values were 0 .82 ± 0 .03 ,0 .79 ± 0 .03 ,respectively .Conclusion mDIXON-Quant which can accuratly quantify fat content could evaluate the lumbar vertebral bone marrow fat content ,reflect the changes of the bone quality ,provide valuable information for the diagnosis of osteoporosis ,and is helpful to predict the risks of the lumbar fragility fracture.

Application of navigator IDEAL-IQ in liver fat quantification:a comparative study with MRS / 实用放射学杂志

Objective To quantitatively assess the liver fat content by Nav IDEAL-IQ and compare with conventional breath-hold IDEAL-IQ and magnetic resonance spectroscopy (MRS).Methods Twenty volunteers,twenty fatty liver patients and twenty patients with other liver diseases were enrolled in this study.IDEAL-IQ,Nav IDEAL-IQ and MRS imaging were performed and fat fraction (FF) were measured respectively.The results were compared by t-test to explore whether there were differences between these groups. Spearman correlation analysis was also used to test the correlation.Results No significant differences in the FF measured by IDEAL-IQ,Nav IDEAL-IQ and MRS in normal volunteers [(4.09±0.82)%,(3.94±0.83)%,(3.92±0.85)%],fatty liver [(15.5±6.1)%,(11.8±6.5)%,(1 2 .4 ± 7 .2 )% ] and other liver lesions patients [(4.20±0.84)%,(4.00±0.94)%,(3.97±0.96)%]were found between these groups (P>0.05). There was a significant positive correlation between Nav IDEAL-IQ and MRS,and the correlation coefficients of these groups were 0.959,0.786 and 0.945,respectively.Conclusion The results of Nav IDEAL-IQ of fat quantification are consistent with MRS results and it increases the success rate of fat quantitative testing.In a word,it is a noninvasive,convenient and accurate way to measure fat fraction.

The value of 3D-DIXON in quantitative diagnosis of non-alcoholic fatty liver disease / 实用放射学杂志

Objective To access the value of three dimensional gradient echo two-point Dixon water-fat separation sequence (3 D-DIXON) in quantitative diagnosis of non-alcoholic fatty liver disease(NAFLD) by comparing with in-phase/opposed-phase (IN/OPP)and proton magnetic resonance spectroscopy (1 H-MRS).Methods A total of 69 patients with NAFLD diagnosed by CT were divided into two groups by the ratio of liver spleen in CT (group A,low-grade fatty liver,n=32;group B,moderate and severe fatty liver,n=37).All patients underwent MR 3D-DIXION,1H MRS and IN/OPP examination twice within 1 week after CT examination.Fat fraction(FF) was evaluated and analyzed respectively.Results Pearson linear correlation analysis showed significant positive correlation between group A and group B about FF3D-DIXON,FFMRs and FFIN/OPP.Area under ROC curve (AUC) was different:AUCsYNTHESIZE＞AUCMRs＞AUCIN/OPP＞AUC3D-DIXON.Kruskal-Wallis H revealed significant difference among the three sequences no matter in group A or group B (P＜0.05).FF values of the three sequences (FF3D-DIXON,FFMRs and FFIN/OPP) were negatively correlated with CT liver/ spleen ratio in each group.The cut-off value of 3D-DIXON,IN/OPP and 1 H-MRS to diagnose presence or absence of fatty liver was 4.9 3 9 ％,5.2 8 4 ％ and 10.4 6 0 ％.Conclusion FF values measured by MRI methods might significantly vary based on different sequences.1 H-MRS is also the main method for quantitative assessment of fatty liver,3D-DIXON showed significant advantage in quantifying moderate and severe fatty liver.

MRI measurement of pancreatic fat fraction based on Dixon method and correlation analysis with clinical factors / 中华放射学杂志

Objective To analyze the pancreatic fat fraction based on magnetic resonance Dixon sequence and correlation with clinical factors. Methods A total of 95 cases of adult physical examinees who had underwent abdominal MRI were retrospectively studied. Age, blood pressure, height and weight were recorded for every subject,and BMI was then calculated.The venous blood sample were analyzed for fasting plasma glucose (FPC), total cholesterol (TC), triglycerides (TG), low density lipoprotein-cholesterol (LDL-c)and high density lipoprotein-cholesterol(HDL-c).All cases underwent water-fat separation T1WI,fat inhibition T2WI, DWI, and coronal T2WI scans. We measured PFF of all the examinees, subcutaneous fat area(SA),visceral fat area(VA),and total abdominal fat area(TA)on the images above 8 centimeter of L4 to L5 were also measured, subcutaneous fat percentage (SFP) and visceral fat percentage (VFP) were further calculated. PFF of the 95 cases ranged from 2.1% to 35.0%, and the median PFF was 8.9%. This cohort was divided into low-fat pancreas groups (PFF≤8.9%, n＝51) and high-fat pancreas group (PFF>8.9%, n＝44) according to the median PFF. Independent sample t test was used to test for differences in clinical index between the two groups, Pearson correlation coefficient was used to measure the strength of a linear association between clinical indexes and PFF. Results Excellent water only, fat only, in phase and out of phase images of all the 95 adults were obtained. Signals of MRI images of all pancreas were homogeneous, the anatomic structures of all images were sharp and clear, and all the images had no motion artifact. The levels of BMI, systolic blood pressure, TG, LDL-c, FPC, VA, TA, VFP of high-fat pancreas group were significantly higher than those of low-fat pancreas group, and SFP was lower (P<0.05). The differences in age, diastolic blood pressure, HDL-c, TC, and SA between the two groups were not statistically significant(P> 0.05). PFF was weakly to moderately positively correlated with age, BMI, systolic blood pressure, diastolic blood pressure, TG, LDL-c, FPG, SA, VA, TA and VFP (r=0.219 to 0.515, P<0.05), SFP was moderately negatively correlated with PFF(r=－0.434, P<0.01). Conclusions It's feasible and accurate to measure the PFF with Dixon technique. PFF have a certain correlation with age, BMI, blood pressure, abdominal fat area and blood lipid metabolism.

Variabilidad en la determinación de fracción grasa muscular en resonancia magnética utilizando la técnica de Dixon / Variability in magnetic resonance quantification of muscle fat fraction using Dixon's technique

Abstract. Muscle MRI has emerged as a valuable tool in the diagnosis of neuromuscular-disorders. The Dixon fat-water separation technique allows objective intra-muscular fat quantification. There are few reports concerning measurement standardisation with Dixon technique. The objective of this study was to evaluate the variability in fat quantification using Dixon's technique in a cohort of patients with congenital myopathies, by analysing intra-segment, intra-muscle, and inter-muscle variability of 60 muscles in each patient. Whole body MRI was performed on 31 patients, 23 with congenital myopathies and 8 healthy controls, aged between 10 months and 35 years old, from January 2014 to June 2016. The mean fat-fraction in healthy patients was around 5%, with less than 2% intra-muscle variability. An intra-muscle variability between 3.1-7.8% was estimated in patients with congenital myopathies. It may be concluded that there is high intra- and inter-muscle fat-fraction variability among patients with congenital myopathies, and this is an observation that should be incorporated in the analysis of fat replacement.

Resumen. La resonancia magnética muscular ha emergido como una valiosa herramienta de apoyo diagnóstico en enfermedades neuromusculares. La técnica de Dixon permite objetivar la fracción grasa muscular, pero no existe consenso sobre la estandarización de estas mediciones. El objetivo de este estudio fue evaluar la variabilidad en la determinación de fracción grasa utilizando la técnica de Dixon, estudiando la variabilidad intrasegmentaria, intramuscular e intermuscular en 60 músculos por paciente. Se realizó RM de cuerpo completo a 31 pacientes: 23 con miopatía congénita y 8 controles, entre 10 meses y 35 años de edad, desde enero del 2014 a junio del 2016. En pacientes sanos se estimó una fracción grasa promedio cercana al 5%, con una variabilidad intramuscular inferior al 2%. En pacientes con miopatías congénitas existe una variabilidad entre el 3,1-7,8%. El estudio permite concluir que existe una alta variabilidad intra e intermuscular en pacientes miopáticos, que no se observa en pacientes sanos.

Correlation Between Vertebral Marrow Fat Fraction Measured Using Dixon Quantitative Chemical Shift MRI and BMD Value on Dual-energy X-ray Absorptiometry

PURPOSE: The purpose of this study was to determine whether there is a significant correlation between vertebral marrow fat fraction measured using Dixon quantitative chemical shift MRI (QCSI) and BMD on dual-energy X-ray absorptiometry (DXA). MATERIALS AND METHODS: This retrospective study included 68 healthy individuals [mean age, 50.7 years; range, 25-76; male/female (M/F) = 36/32] who underwent DXA of the L-spine and whole body MRI including QCSI of the L-spine and chemical shift MRI of the liver. The enrolled individuals were divided into subgroups according to sex and T-score [i.e., normal bone density (M/F=27/23) and osteopenia (M/F=9/9)]. Vertebral marrow (Dixon QCSI, TR/TE 10.2/4.8 ms) and hepatic fat fractions (chemical shift technique, TR/TE 110/4.9 and 2.2 ms) were calculated on MRI. We evaluated whether there were significant differences in age, body mass index (BMI), vertebral marrow fat fraction, or hepatic fat fraction among the subgroups. Whether or not the participant had reached menopause was also evaluated in females. The correlations among variables (i.e., age, BMI, vertebral marrow and hepatic fat fractions, BMD) were evaluated using Spearman's correlation method. RESULTS: There were no significant differences in age, BMI, or vertebral marrow and hepatic fat fractions between the two male subgroups (normal bone density vs. osteopenia). In female subjects, mean age in the osteopenic subgroup was greater than that in the normal subgroup (p=0.01). Presence of menopause was more common in the osteopenic subgroup [77.8% (7/9)] than the normal subgroup [26.1% (6/23), p<0.05]. The other variables showed no significant difference between female subgroups. The only significant correlation with marrow fat fraction after partial correlation analysis was that with age in the female subjects (r=0.43, p<0.05). CONCLUSION: The vertebral marrow fat fraction calculated using the Dixon QCSI does not precisely reflect the mild decrease in BMD for either sex.

Study of ~1H MR Spectroscopy of Vertebral Body Marrow / 实用放射学杂志

Objective To study the changing of vertebral body marrow fat fraction(FF) in different age and sex and the relation-ship between FF and bone mineral densities (BMD). Methods Eighty-five healthy volunteers aged from 21 to 70 years old and twenty patients with osteoporosis based on T score after dual X-ray absorptionmetry examination underwent proton magnetic reso-nance spectroscopy (MRS) in L_3 vertebral bodies. The volunteers were divided into five groups according to the age(10 years and 16～18 cases in each group). Results The FF values in 21～30 years group,31～40 years group,41～50 years group,51～60 years group , >60 years group and the osteoporotic group were 30.7%±4.4%, 35.5%±6.8% , 41.9%±6.6%, 46.8%±5.5%, 51.7%±5.2% and 59.2%±7.4%, respectively. The FF values in L_3 vertebral bone marrow in men were high than that in women in the same age group (P<0.05) except >60 years group. There was negative correlation between marrow fat content and T score in osteoporotic group(γ=-0.6, P<0.01). Conclusion The vertebral marrow fat content in healthy adults was significantly in-creased with the aging. MRS may be used as a new way to evaluate the physiological and pathological process of bone marrow.