Objective:To explore the value of iterative decomposition of water and fat with asymmetry and least squares estimation-quantitative fat imaging (IDEAL-IQ) in quantitative evaluation of thigh muscle fat content and its correlation with muscle strength in middle-aged and elderly volunteers.Methods:From December 2020 to April 2021, 30 volunteers aged 45 to 70 were recruited prospectively, including 15 males and 15 females with 52.5 (49.0, 56.3) years old. All subjects were scanned at 3.0 T MR, including axial T 1WI, IDEAL-IQ and coronal T 2WI of the left thigh. The region of interest of the knee extensors (quadriceps femoris) and knee flexors (hamstrings) in the left mid-thigh were delineated, and muscle cross-sectional area (CSA), skeletal muscle index (SMI), intermuscular fat fraction (FF) and intramuscular FF were obtained. In addition, isokinetic muscle strength measurement was performed on the left knee joint of all subjects at angular speeds of 60°/s and 180°/s to obtain peak torque (PT) and total work (TW) of knee flexors and extensors. Independent sample t-test, paired t-test or Mann-Whitney U test were used to compare the differences of CSA, SMI, intermuscular FF, intramuscular FF, PT and TW between different genders and muscle groups. Pearson or Spearman correlation analysis, and multiple linear regression analysis were used to analyze the correlation between CSA, SMI, intermuscular FF, intramuscular FF and PT, TW of thigh muscles. Results:The CSA, PT and TW of thighs in males were higher than those in females ( P<0.05), while the intermuscular FF in males was lower than that in females ( P=0.005). The CSA, SMI and PT of the thigh extensors were higher than those of the flexors ( P<0.001), while the intramuscular FF and intermuscular FF were lower than those of the flexors ( P<0.001). Intramuscular FF of flexors and extensors were moderately negatively correlated with PT ( r=-0.635, P<0.001; r=-0.546, P<0.001), and highly, moderately negatively correlated with TW ( r=-0.718, P<0.001; r=-0.616, P<0.001). Intermuscular FF of flexors and extensors were moderately negatively correlated with PT ( r=-0.519, P=0.003; r=-0.443, P=0.014), and negatively correlated with TW ( r=-0.363, P=0.049; r=-0.552, P=0.002). There was no significant correlation between CSA, SMI and PT, TW in flexors and extensors of thigh ( P>0.05). Multiple linear regression analysis showed that intramuscular FF was still significantly correlated with PT and TW of flexors and extensors (flexors: R 2adj=0.505, P=0.001; R 2adj=0.540, P<0.001; extensors: R 2adj=0.351, P=0.006; R 2adj=0.470, P=0.002). Conclusion:FF based on IDEAL-IQ technology can accurately quantify the intramuscular and intermuscular fat content of thighs, and there are negative correlations between intramuscular FF, intermuscular FF and isokinetic muscle strength measurements including PT and TW. Among them, intramuscular FF is more significant.

Objective ToinvestigatetheMRIandCTimagingcharacteristicsofcerebralpleomorphicxanthoastrocytoma(PXA). Methods CTandMRImanifestationsof5cerebralPXAcasesconfirmedbypathologywereanalyzedandcomparedwiththosecases reportedindocumentation.Results The meanageof5caseswas (27±18)years,andallthecasesrespectivelyhadsinglelesion whichwaslocatedinthecortexorsubcortex.In5cases,3leionsoccurredinthetemporallobe,while1lesioninthefrontallobeand1 lesioninthecerebellarvermis.Solid-cystictumorsin3casesandsolidtumorsin2cases(including1casewithpartialpiamaterinfiltrated) wereidentifiedbyCTandMRI.ThecysticpartoflesionwasshownaslowdensitywhilethesolidpartasmixeddensityonplainCT scan,including1casewithscatteredpoint-stripecalcification.Thesolid-cysticcapsuleandthesolidpartoflesionweredemonstrated asuniform markedenhancementonenhancedCTscan.ThesolidareaoftumorwasshownasslightlyhypointenseonT1WI,slightly hyperintenseonT2WI,markedenhancement,andequisignalorhyperintenseonDWIimage.Thesolid-cysticcapsulewallwasenhanced in3cases,whilethecysticpartwasnotenhanced.ThemildtomoderateedemaaroundthetumorwasdetectedinalltumorsbyCT and MRI.Conclusion PXAoccursmostfrequentlyinthetemporallobeofadolescents.TypicalcharacteristicsofCTandMRIaresolid-cystic massandmarked-enhancementofwallnodule,withdifferentdegreeofedemaaroundthetumor.

Objective To investigate the predictive value of CT signs in the pathological Fuhrman grading of clear cell renal carcinoma (ccRCC).Methods The clinicopathological features and CT findings of 72 patients with ccRCC which confirmed by operation and pathology were analyzed retrospectively.According to the WHO Fuhrman grading,all patients were divided into low-grade(Fuhrman gradeⅠorⅡ)or high-grade (Fuhrman gradeⅢorⅣ).ChiG square test and t-test were used to compare the clinical data and CT findings between the two groups,including morphological features (site,whether the renal medulla invasion,morphology,growth pattern,border,pseudo-envelope,lobulation sign,interface,perirenal fascia and the same lateral adrenal invasion,renal sinus and perirenal fat invasion,venous invasion,lymphadenopathy, maximum diameter),density (bleeding,necrosis ratio,calcification,fat)and enhancement characteristics (the degree of enhancement, strengthening method).And the pathological Fuhrman grading was the gold standard.The ROC was used to analyze the diagnostic efficacy of CT signs on Fuhrman grading.The Delong test was used to compare the AUC of different CT signs.Results There were significant differences in tumor maximum diameter,the renal medulla invasion,and lobulation sign between the Fuhrman low-grade and high-grade group(χ2/t＝－4.31 7,9.794,7.325,P＜0.05).There were no differences in gender,age,location sign,morphology,growth pattern, border,pseudo-envelope,interface,perirenal fascia and ipsilateral adrenal invasion,renal sinus and perirenal fat invasion,necrosis ratio,degree of enhancement,strengthening method between two groups (P＞0.05). The largest diameter of the tumor,the renal medulla invasion and the lobulation sign were useful for Fuhrman diagnosis.The AUC was 0.778,0.647 and 0.644,respectively.And there were significant differences between the maximum diameter and the renal medulla invasion or lobulation sign (P＜0.05).Conclusion The maximum diameter,medulla and lobular sign can predict the Fuhrman grading of ccRCC,and the maximum diameter prediction is the most accurate.