OBJECTIVE To analyze the influencing factors for achieving target plasma drug concentration （trough） （abbreviated as “PDC”） of vancomycin in patients from high-altitude regions and establish a predictive model for PDC using single- center data， providing references for rational clinical drug use. METHODS Inpatients with vancomycin （1 g， q12 h） administered intravenously in our hospital from January 2021 to June 2024 were retrospectively included. Demographic data， liver and kidney function and hematological indexes were collected. Spearman correlation analysis was used to evaluate the correlation between vancomycin PDC and each detection index. Univariate analysis was used to evaluate the differences of each index in patients with different PDC， and the effects of different gender， body mass index， age and underlying diseases （hypertension/diabetes） on vancomycin PDC. Based on the results of correlation analysis and univariate analysis， multiple linear stepwise regression analysis was used to obtain the independent predictors of vancomycin PDC and construct the prediction model. RESULTS A total of 141 patients were included， with an overall attainment rate of 46.81% for the target PDC of vancomycin. Correlation analysis showed that the vancomycin PDC was positively correlated with age， blood urea nitrogen， uric acid （UA）， serum creatinine （CRE） and β2- microglobulin （β2-MG）， and negatively correlated with height， weight， creatinine clearance rate （CCR）， glomerular filtration rate （GFR）， alanine transaminase （ALT）， hemoglobin （HGB）， white blood cell count and neutrophils （P＜0.05）. There were significant differences in age， CRE and other 14 indexes among different PDC groups （P＜0.05 or P＜0.01）. Age and underlying diseases had significant effects on vancomycin PDC （P＜0.05 or P＜0.01）. CCR， direct bilirubin （DBil）， β2-MG， UA， HGB and height （standardized coefficients were －0.371， 0.367， 0.169， 0.232， －0.140， －0.132； P＜0.05） were independent predictors of vancomycin PDC. The F value of the regression equation was 34.858 （P＜0.05）， the R2 was 0.610， and the adjusted R2 was 0.592. CONCLUSIONS The vancomycin PDC of patients in high-altitude regions is affected by multiple factors such as renal function， liver function and hematological indexes. CCR， HGB and height could be used to predict vancomycin PDC negatively， while DBil， β2-MG and UA could be used to predict vancomycin PDC positively. The variables of the established prediction model could explain 59.2% of the variation of vancomycin PDC.

Meropenem （MEM） is one of the important drugs for the treatment of severe infections， but the standard dose is often difficult to achieve an effective therapeutic concentration target. This article reviews the related studies on the population pharmacokinetics of MEM in patients with severe infection. It is found that the apparent volume of distribution （Vd） and clearance rate are the most important factors affecting the dose adjustment， and the factors affecting Vd include serum albumin， age， overall weight， shock status， and chest/abdomen/cerebrospinal fluid drainage. The main factors affecting the clearance rate were renal function， renal replacement therapy treatment mode and combination therapy. For adult patients with severe infections in China， MEM is recommended to be administered in an individualized manner based on glomerular filtration rate， with a dosage range of 500 to 1 500 mg given every 4 to 6 hours， and prolonged infusion is preferred. When the minimum inhibitory concentration （MIC） of the pathogenic bacteria reaches 64 mg/L， therapeutic drug monitoring is required. For therapeutic efficacy， it is essential to ensure that the trough concentration remains above the MIC； to prevent drug resistance， it should be maintained above 4×MIC. Regarding safety， it is recommended that the upper limit of the trough concentration be 32 mg/L， and blood sampling for monitoring can be conducted as early as after 1 to 2 doses of administration.

Objective To explore the imaging characteristics and make the differential diagnosis of intraspinal extramedullary epidural lesions. Methods 23 cases with intraspinal extramedullary epidural lesions confirmed by puncture or surgical pathology were selected for retrospective analysis of the lesion morphology,MRI signs and the relationship between the lesion and surrounding tissues.Results Intraspinal extramedullary epidural lesions were more often located at thoracic spinal canal.The shapes of lesions were always various.The malignant tumors were irregular.It could damage the adjacent bone and grew surrounding the spinal cord.Leaping growth and multiple vertebral involvements could be seen in metastasis.The complex components of lesions were related to heterogeneous signal intensity on MRI,which could be presented with hypoGto hyperGintense on T1 WI and T2 WI.The angiolipoma showed hypoGto hyperGintense on T1 WI,and the hyperGintense signal could be suppressed with fatGsuppressed sequence.Meningioma tended to present with homogeneous signal on both T1 WI and T2 WI, with dural tail on contrast MRI.All of the lesions were moderately or significantly enhanced on contrast MRI.Conclusion Intraspinal extramedullary epidural lesions include a wide range of lesions,and the components of lesions are very complex.Among them,the distinctive MRI characteristics include the lesions containing fat and vascular components,besides malignant lesions invading adjacent tissues.Comprehensive analysis of the shape and signal of lesions,as well as the relationship between lesions,and surrounding structures is very helpful in differential diagnosis of intraspinal extramedullary epidural lesions.

Objective To analyze the mammographic features of invasive lobular carcinoma (ILC)compared to those of invasive ductal carcinoma (IDC).Methods Twenty cases with ILC and 95 cases with IDC were retrospectively evaluated by two breast radi-ologists according to the Breast Imaging Reporting and Data System (BI-RADS)lexicon.The mammographic findings were com-pared between ILC and IDC with the independent samples chi-square test or Fisher’s exact test,as appropriate.Results Mass was the most common finding in both ILCs and IDCs,but less frequent in ILCs (36.4% vs 63.9%,P =0.008).Mass in ILCs was more frequently lobular or irregular shape with spiculated margin.Architectural distortion and focal asymmetry were more frequent in ILCs than in IDCs,however,the differences were no significant.The frequency of calcifications was not significantly different between the two groups.The distributions of calcifications were more regional in ILCs,and more segmental or linear in IDCs (P =0.01).Conclu-sion ILCs are more usually shown as non-mass appearances on mammography.ILCs that appeared as mass are more frequently ir-regular in shape with spiculated margins.