BACKGROUND:It is necessary to carry out multiple operations to remove the scar in patients with large area of scar, and whether the scar tissue can be recycled has become the focus of the study. OBJECTIVE:To compare the tissue structure, biomechanical properties and biocompatibility of the acel ular dermal matrix of mature scar tissue and normal skin. METHODS:The acel ular dermal matrix was prepared from the human mature scar tissue and the normal skin around the scar. Subsequently, histological and scanning electron microscope observations were performed, and biomechanical properties were detected using universal tensile testing machine. Then, the acel ular dermal matrix from mature scar tissue and normal skin was co-cultured with fibroblasts for 10 days, respectively, and the cel growth curve was drawn. Additional y, the acel ular dermal matrix from mature scar tissue and normal skin was subcutaneously implanted into the dorsal tissue of Sprague-Dawley rats, respectively and histological observation was conducted at 4, 8 and 12 weeks after implantation. RESULTS AND CONCLUSION:There were many gaps but no cel ular components in the acel ular dermal matrix, in both two groups. Col agen fibers of the acel ular dermal matrix derived from mature scar were looser than that of the normal skin, and arranged slightly irregularly;the biomechanical properties of the acel ular dermal matrix derived from mature scar were similar to that of the normal skin, which exhibited appropriate flexibility and strength. There was no significant difference in the growth state of the two kinds of acel ular dermal matrix, and the growth curve was basical y consistent. After 4 weeks of implantation, more inflammatory cel s infiltration could be found in the mature scar group, and in contrast, only a few inflammatory cel s infiltration appeared in the normal skin group, These inflammatory reactions disappeared with time in both two groups. Besides, col agen fibers arranged in neat, and smal vessels grew into the implants in both two groups. In conclusion, the tissue structure, biomechanical properties and biocompatibility of the acel ular dermal matrix derived from scar tissue are almost consistent with those of the human normal skin.

Objective: To investigate the application value of CTDI_vol and size-specific dose estimate(SSDE) in evaluating the radiation dose of adult chest CT. Methods: A retrospective analysis was made on the CTDI_voland SSDE of 128 patients who underwent chest CT scanning in the First Affiliated Hospital of Zhejiang Chinese Medical University from March to April 2017 and all images are adequate for diagnosis. The subjects were divided into three groups according to body mass index (BMI): Group A, 38 cases with 16≤BMI<21.1 kg/m²; Group B, 53 cases with 21.1≤BMI<23.9 kg/m²; Group C, 37 cases with 23.9≤BMI<34.1 kg/m². The diameters of anterior-posterior (AP) and left-right (LAT) of each patient were measured in the slice of nipple level, and CTDI_vol, effective diameter (ED), conversion factor (f_size) and SSDE of each patient were recorded and calculated. Meanwhile, the differences between CTDI_vol and SSDE in different BMI groups were compared. Results: SSDE of each group was higher than CTDI_vol, and increased by 50.13%, 42.83% and 33.68% in group A, B and C, respectively. There were significant differences in radiation dose between CTDI_vol and SSDE in the three groups (t=-48.873, -57.001, -32.651, P<0.05). There were significant differences in ED, f_size, CTDI_vol and SSDE among the three groups (F=51.456, 47.749, 113.916, 106.449, P<0.05). Conclusions SSDE can evaluate the radiation dose absorbed by patients with different body types in chest CT, while CTDI_vol underestimated the radiation dose.The lower BMI, the greater the underestimated dose value, the more radiation dose absorbed.

Objective: To assess the value of multi-parametric MRI in mammographically detected breast imaging reporting and data systems (BI-RADS) 3 to 4 exclusive microcalcifications. Methods: A retrospective analysis was performed in 152 patients with mammographically detected BI-RADS 3 to 4 exclusive microcalcifications from January 2013 to December 2017. All patients underwent bilateral breast multi-parametric MRI before surgical biopsy. Microcalcifications were classified according to BI-RADS by two radiologists with more than 10 years′ experience in breast imaging. The area under the curve (AUC), sensitivity and specificity of BI-RADS 3 to 4 exclusive microcalcifications diagnosis by mammography and mammography plus MRI were calculated and compared using pathology as the gold standard. Results: A total of 152 lesions (93 benign lesionsand 59 malignant lesions) were assessed in this study. The positive predictive value (PPV) of mammography for BI-RADS 3, 4A, 4B and 4C microcalcifications diagnosis were 22.2%(16/72), 5.0%(1/20), 48.5%(17/35) and 100.0%(25/25) respectively. The PPV of MRI for BI-RADS 2, 3, 4, 5 microcalcifications diagnosis were 1.6%(1/62), 7.1%(2/28), 72.2%(13/18) and 97.7%(43/44).The area under curve, sensitivity and specificity of mammography for BI-RADS 3 to 4 microcalcifications diagnosis were 0.676,72.9% and 60.2%. The area under curve, sensitivity and specificity of mammography plus MRI for BI-RADS 3 to 4 microcalcifications diagnosis were 0.982, 94.9% and 93.6%. Conclusions Multi-parametric MRI can improve the diagnostic accuracy in mammographically detected BI-RADS 3 to 4 exclusive microcalcifications, which is helpful to differentiate benign and malignant breast lesions with microcalcifications and avoid unnecessary biopsies.