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Objective:To explore MRI T 2-mapping and blood oxygenation level dependent (BOLD) to evaluate the functional changes of paraspinal muscle in rats with discogenic low back pain (DLBP) after swimming. Methods:Totally 54 female 1-month-old SD rats were selected, which were divided into 3 groups by random number table method, sham operation (Sham) group, DLBP non-swimming group and DLBP swimming group, with 18 rats in each group. Under the guidance of X-ray fluoroscopy, the L4/5 and L5/6 intervertebral discs of the rats in the DLBP non-swimming group and DLBP swimming group were punctured by the posterior approach, and establishment of DLBP rat model by destroying nucleus pulposus, and only paraspinal muscles at the same level were punctured in the Sham group. After modeling, the DLBP swimming group received swimming exercise intervention for 5 consecutive days (30 min/d), while the DLBP non-swimming group and Sham group did not receive any rehabilitation exercise intervention. Each group was divided into 3 time point subgroups on average, the T 2-mapping and BOLD sequences were scanned at 30, 90 and 180 days after modeling to obtain the T 2 value, R 2* value of the paraspinal muscles, and the paraspinal muscles at the modeling level were taken for immunofluorescence staining, and the fluorescence intensity of myosin heavy chain (MYH)1 (type Ⅱ muscle fiber) and MYH7 (type I muscle fiber) was analyzed. One-way analysis of variance was used for comparison among the 3 groups, and the Bonferroni method was used for multiple comparisons, and Pearson correlation coefficient was used to evaluate the correlation between quantitative MRI parameters T 2 value, R 2* value and MYH1, MYH7 immunofluorescence intensity of rat paraspinal muscles at 180 days after modeling. Results:At 30 days after modeling, there was no significant difference in T 2 value and R 2* value among the 3 groups (all P>0.05). At 90 days after modeling, the T 2 value of the DLBP swimming group was higher than that of the DLBP non-swimming group, and the T 2 value of the DLBP non-swimming group was lower than that of the Sham group (all P<0.05), and there was no significant difference in the R 2* value among the 3 groups ( P>0.05). At 180 days after modeling, the T 2 value of the DLBP swimming group was higher than that of the DLBP non-swimming group, and the R 2* value was lower than that of the DLBP non-swimming group; the T 2 value of the DLBP non-swimming group was lower than that of the Sham group, and the R 2* value was higher than that of the Sham group (all P<0.05). At 30 and 90 days after modeling, there was no significant difference in the expressions of MYH1 and MYH7 among the 3 groups (all P>0.05). At 180 days after modeling, the expression of MYH1 decreased and the expression of MYH7 increased in the DLBP swimming group compared with the DLBP non-swimming group; the expression of MYH1 increased and the expression of MYH7 decreased in the DLBP non-swimming group compared with the Sham group (all P<0.05). At 180 days after modeling, the T 2 value had a moderate negative correlation with the fluorescence intensity of MYH1 ( r=-0.511, P=0.043), and a moderate positive correlation with the fluorescence intensity of MYH7 ( r=0.564, P=0.023); R 2* value was moderate positive correlated with the fluorescence intensity of MYH1 ( r=0.625, P=0.010), and moderate negative correlated with the fluorescence intensity of MYH7 ( r=-0.653, P=0.006). Conclusions:Swimming exercise can improve the reduction of water content and perfusion in the paraspinal muscles of DLBP rats, and reduce the transformation of muscle fibers from type Ⅰ to type Ⅱ, the changes of T 2 and R 2* value can reflect the transformation of paraspinal muscle fiber types to a certain extent.
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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.
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Objective:To explore the classification performance of combined model constructed from CT signs combined with radiomics for discriminating COVID-19 pneumonia and other viral pneumonia.Methods:The clinical and CT imaging data of 181 patients with viral pneumonia confirmed by reverse transcription-polymerase chain reaction in 15 hospitals of Yunnan Province from March 2015 to March 2020 were analyzed retrospectively. The 181 patients were divided into COVID-19 group (89 cases) and non-COVID-19 group (92 cases), which were further divided into training cohort (126 cases) and test cohort (55 cases) at a ratio of 7∶3 using random stratified sampling. The CT signs of pneumonia were determined and the radiomics features were extracted from the initial unenhanced chest CT images to build independent and combined models for predicting COVID-19 pneumonia. The diagnostic performance of the models were evaluated using receiver operating characteristic (ROC) analysis, continuous net reclassification index (NRI) calibration curve and decision curve analysis.Results:The combined models consisted of 3 significant CT signs and 14 selected radiomics features. For the radiomics model alone, the area under the ROC curve (AUC) were 0.904 (sensitivity was 85.5%, specificity was 84.4%, accuracy was 84.9%) in the training cohort and 0.866 (sensitivity was 77.8%, specificity was 78.6%, accuracy 78.2%) in the test cohort. After combining CT signs and radiomics features, AUC of the combined model for the training cohort was 0.956 (sensitivity was 91.9%, specificity was 85.9%, accuracy was 88.9%), while that for the test cohort was 0.943 (sensitivity was 88.9%, specificity was 85.7%, accuracy was 87.3%). The AUC values of the combined model and the radiomics model in the differentiation of COVID-19 group and the non-COVID-19 group were significantly different in the training cohort ( Z=-2.43, P=0.015), but difference had no statistical significance in the test cohort ( Z=-1.73, P=0.083), and further analysis using the NRI showed that the combined model in both the training cohort and the test cohort had a positive improvement ability compared with radiomics model alone (training cohort: continuous NRI 1.077, 95 %CI 0.783-1.370; test cohort: continuous NRI 1.421, 95 %CI 1.051-1.790). The calibration curve showed that the prediction probability of COVID-19 predicted by the combined model was in good agreement with the observed value in the training and test cohorts; the decision curve showed that a net benefit greater than 0.6 could be obtained when the threshold probability of the combined model was 0-0.75. Conclusion:The combination of CT signs and radiomics might be a potential method for distinguishing COVID-19 and other viral pneumonia with good performance.
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Objective:To explore the clinical application value of MRI in quantitative evaluation of anterior cruciate ligament mucoid degeneration (ACL-MD).Methods:From March to July 2020, 40 patients who were scheduled to undergo arthroscopic treatment were prospectively collected in the First Affiliated Hospital of Kunming Medical University.The anterior cruciate ligament tissue from the lateral edge of the tibial end was taken during the operation. Based on the pathologicalre sults, the patients were divided into the ACL-MD group ( n=19) and the normal group ( n=21). The sagittal plane three-dimensional steady-state rapid precession (3D-FIESTA), T 1 mapping, T 2 mapping, and T 2* mapping were performed before the knee joint surgery, and the scanned images were post-processed and analyzed to measure the T 1, T 2, and T 2* values of the tibial end of the anterior cruciate ligament.The relaxation time of the ACL-MD group and the normal group was compared using independent sample t test. The ROC curve was drawn using each parameter and the areas under the curve (AUC) for the diagnosis of ACL-MD were obtained.DeLong test was used to compare the differences of AUCs. Results:The T 1 [(1 291.9±273.4) ms], T 2 [(54.8±10.6) ms], and T 2* values [(30.6±6.4) ms] of anterior cruciate ligaments in the ACL-MD group were significantly higher than those in the normal group [ (1 087.0±121.0), (44.8±7.1), (20.4±4.8) ms; t=3.011, 3.473, 5.658, all P<0.001]. The AUCs of T 1, T 2, T 2* were 0.747, 0.764, 0.912, sensitivity of 63.2%, 63.2%, 100%, and the specificity of 100%, 95.2%, 76.2% in diagnosing ACL-MD. The AUC of the T 2* value was higher than those of the T 1 and T 2 values, and the differences were statistically significant ( Z=1.734, 2.162, P=0.043, 0.031). Conclusion:T 1, T 2, T 2*values measured by MRI quantitative imaging have high performance in assessing knee joint ACL-MD, and T 2* value has the largest AUC and the highest diagnostic efficiency.
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Objective To investigate the feasibility of morphology and quantitative parameters for evaluation of lymph node metastatic (LNM) potential in papillary thyroid microcarcinoma (PTMC) with dual?energy CT iodine image. Methods The ninety?five PTMC patients (59 patients with LNM, 36 patients without LNM in the neck) whom underwent dual?energy contrast scanning and confirmed by first postoperative pathology results were enrolled in this retrospective study from July 2014 to December 2016. Dual?energy iodine images were obtained by the dual?energy post?processing software. The iodine image morphology of each patient was analyzed, including size, number, aspect ratio, shape, uncompleted enhanced ring sign, nodule which breaks through the thyroid capsule, microcalcification, and enhanced?degree, and diagnostic efficiency of each imaging feature was calculated. The iodine concentration (IC) and CT value of PTMC solid parts were measured in arterial phase and venous phase images respectively, as well as the NICnod (normalized iodine concentration) and normalized CT value. The independent sample t test was performed to compare quantitative parameters between the LNM group and non?LNM group. ROC curves with quantitative parameters of two phases were used to analyze the diagnostic efficiencies of NIC and normalized CT value. Results Statistically, in the iodine image, the imaging features of LNM group, including multiple lesions, maximum diameter of nodules, aspect ratio, irregular shape, uncompleted enhanced ring sign, and nodule which breaks through the thyroid capsule, had significant differences compared with those of non?LNM group in the neck (χ2 were 14.965,8.724,11.494,8.097,6.324,23.272;P all<0.05), and there were positive correlations with LNM potential (r were 0.397,0.303,0.348,0.309,0.258, 0.495;P all<0.05), the diagnostic efficiency of nodule which breaks through the thyroid capsule was the highest among the imaging features for diagnosis of cervical LNM (sensitivity 77.9%, specificity 72.2%, accuracy 75.8%). During the artery phase, mean NICROI and normalized CT value of non?LNM group were respectively 0.29±0.10,0.33±0.11,and these of LNM group were respectively 0.45±0.15,0.44±0.13.NICROI and normalized CT value of non?LNM group were less than LNM group′s (t=-4.891,－3.462;P all<0.001). During the venous phase, NICROI and normalized CT value of LNM group were higher than non?LNM group′s (t=-3.381,－2.18;P all<0.05). Among all quantitative parameters, the NIC of arterial phase has the highest diagnostic efficacy for the diagnosis of cervical LNM. The area under the ROC curve (AUC) was the largest, 0.814, the sensitivity was 73.5%, the specificity was 79.2%, and the diagnostic threshold was 0.208. Conclusion Dual?energy CT iodine image morphology and quantitative parameters have important clinical value for evaluation of cervical lymph node metastatic potential in PTMC.
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Objective To explore the value of T2-mapping imaging in assessment of lumbar dorsal extensors group (multifidus,longissimus and iliocostalis) function before and after exercises in healthy volunteers.Methods Totally 50 healthy young volunteers underwent T2-mapping imaging before and after exercises.T2 value and cross-section area (CSA) of multifidus,longissimus and iliocostalis were measured at the level of L3 and 14 superior border.Differences of CSA and T2 value were compared between left and right side muscles before and after exercises.The correlation between CSA difference and T2 difference before and after exercises was analyzed.Results At the level of L3 and L4 superior border,CSA and T2 value of bilateral multifidus,longissimus and iliocostalis increased after exercises (all P＜0.05).At the level of L3 superior border,CSA after exercises and CSA difference of left multifidus were higher than those of right side (all P＜0.05).Before exercises,there were statistical differences of T2 values on left and right side of longissimus and iliocostalis at the level of L3 superior border and the longissimus at the level of L4 superior border (all P＜0.05).Positive correlations were found between CSA difference and T2 difference on bilateral iliocostalis at the level of L3 and L4 superior border,as well as on bilateral multifidus at the level of L4 superior border (all P ＜0.05).Conclusion T2-mapping imaging can be used to assess the activity state of lumbar dorsal extensors group before and after exercises.
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Objective To investigate the feasibility of 80 kV and low tube current on brain CT perfusion(CTP).Methods Sixty patients underwent 80 kV CTP examination,and were randomly divided into five groups according to different tube currents,A group (40 mAs),B group (60 mAs),C group (80 mAs),D group (100 mAs),E group (150 mAs).Twelve patients in each group were selected to analyze the parameters of the caudate nucleus and white matter frontals and temporal,including CBV,CBF and MTT.Subjective image quality,CT value,SD,SNR,CNR and radiation dose were measured and calculated in the 5 groups respectively.Results Differences of CBV and CBF in the caudate nucleus and white matter frontals were existed among A group,B group,and E group (P＜0.05).There were no significant differences of CT value among the 5 groups (P＞0.05).For the SD and SNR,E group was better than A-D groups (P＜0.05).The CNR was higher in E group than that in A group (P＜0.05).The subjective image quality score evaluation in C,D groups were not lower than that in E group(P ＞0.05).The ED of A-D groups were all lower than that of E group (P＜0.05).Conclusion 80 kV/80 mAs brain CTP can obtain accurate perfusion parameter and satisfied image quality,and the radiation dose can be reduced by 46.22％ (2.42 mSv).