Application Of High-resolution MR Imaging In The Diagnosis Of Skin Neoplastic Lesions

Part I Experimental study of microspocy coil MR imaging in judging the thickness of maxillofacial skin tumorObjective:To investigate the value of high-resolution magnetic resonance imaging in the imaging diagnosis of maxillofacial skin tumors,and to explore its clinical application prospect.Methods:Eight healthy volunteers aged 20 and 30 years old underwent high resolution magnetic resonance imaging(HR-MRI)of normal facial skin.Two senior radiologists independently observed and scored the image quality of each sequence of MR(T1WI,T2WI),and Kappa analysis was used to compare the subjective scores of the two observers.Fifteen patients with maxillofacial skin tumors confirmed by operation and pathology and complete clinical data were collected and examined by HR-MRI before operation.Two radiologists measured the thickness of the primary tumor and recorded the invasion level on HR-MR images(T1WI and T2WI sequence),and compared with the histopathological results.Consistency correlation coefficient(CCC)and Bland-Altman graphic analysis were used to evaluate the consistency of the two measurement results,and intra-group correlation coefficient(ICC)was used to evaluate intra-observer repeatability.Results:Among the 8 healthy volunteers,the average scores on T1WI and T2WI were 2.75,2.5 respectively.The images of 7 cases could clearly show the three layers of anatomical structure of epidermis,dermis and subcutaneous fat,the epidermis was narrow and slightly high signal intensity,the dermis was slightly wider than the epidermis and showed low signal intensity,and the subcutaneous fat layer was the widest and showed uniform high signal intensity.The fat lobule structure divided into fibrous septum can be seen.The subjective score of image quality in each sequence was consistent(Kappa?1).The depth of tumor invasion measured by HR-MRI in 15 patients with maxillofacial skin tumors was in good agreement with that measured by pathology(CCC>0.95),and the consistency was the best on T1WI sequence,but there was no significant difference between the two methods by Bland-Altman graphic analysis.The ICC in the observer was greater than 0.98 and had high repeatability.The invasion levels of the lesions judged on HR-MRI were consistent with the results of operation and pathology.Conclusion:High-resolution magnetic resonance imaging can clearly show the anatomical structure of each layer of the skin,and can accurately judge the depth of invasion and invasion of skin tumors,which is expected to provide more valuable information for the accurate treatment of skin tumors.Part ? The value of high-resolution conventional MR imaging combined with dynamic contrast-enhanced sequence in the differential diagnosis of benign and malignant skin massesObjective:To explore the application value of high resolution MRI combined with dynamic contrast enhanced sequence quantitative parameter analysis in imaging diagnosis and differential diagnosis of skin tumors.Materials and methods:The clinical and imaging data of 54 patients with benign and malignant skin lesions were collected.All patients were examined by plain HR-MRI and dynamic contrast enhanced MRI(DCE-MRI)before operation.50 patients with good MRI images and confirmed by operation and pathology were divided into benign group and malignant group.The features of conventional HR-MR images including tumor sizes,margins,cutaneous layer involvement,the presence of involvement in bone or muscle,strengthening feature,and the results of surgical pathology were investigated.Ktrans,Kep,Ve values,and the time-signal curve(TIC)types were determined using DCE images.Statistical analyses were performed using the chi-square test,Mann-Whitney U tests,and receiver operating characteristic(ROC)curve analysisResults:30 cases were malignant and 20 benign.Age(mean ages of benign/malignant tumors,46.5/80 years;P=0.0005)influenced the distinction between benign and malignant tumors.There were significant differences in MR features such as edge,base,invasion level,tumor necrosis,enhancement mode,bone or muscle involvement between benign and malignant skin tumors(P<0.005).The average values of Ktrans and Kep of DCE quantitative parameters obtained by Tofts model in malignant group were significantly higher than those in benign group(0.23/min vs.0.06/min and 0.49/min vs.0.21,P<0.001).There was no significant difference in sex,lesion size and ve value between the two groups(P>0.05).The area under the working characteristic curve of the subjects showed that Ktrans was superior to Kep in distinguishing benign and malignant skin tumors(0.957>0.897).The type III curve was found in 26(all were malignant tumors),the type II curve in 4(all were benign tumors);and type I curve in 20(malignant for 4 and benign for 16),with a statistically significant difference between malignant and benign lesions(P<0.005).Conclusion:There are some differences in MR findings between benign and malignant skin tumors.When the skin mass showed unclear boundary,internal necrosis,obvious enhancement,Ktrans>0.137 min-1 and outflow type TIC(type III),it was highly suggested to be malignant.HR-MRI combined with DCE quantitative parameters are helpful for the differential diagnosis of benign and malignant skin tumors.