Purpose To explore the diagnostic value of double exponential model for pelvic lesions using 3.0T MRI for the diagnosis of pelvic lesion. Materials and Methods Fifty patients with pelvic lesions (30 benign cases and 20 malignant cases) underwent MR750-diffusion weighted imaging (DWI) scans, with b values of 0, 50, 300, 600, 800 and 1200 s/mm2, Functool-MADC software was used on AW 451 workstations for data processing, Slow ADC value, Fast ADC value, Standard ADC value, Fraction of fast ADC value were recorded and compared between benign and malignant lesions, and Standard ADC images were fused with axial T2 fat-suppressed images. Results Slow ADC values [(1.83±0.86)×10-3 mm2/s] and Standard ADC values [(1.79±0.78)×10-3 mm2/s] of benign lesions were larger than those of the malignant lesions [Slow ADC values:(1.05±0.31)×10-3 mm2/s;Standard ADC values:(1.13±0.39)×10-3 mm2/s] (t=3.90, 3.51;P<0.01), and the difference of Slow ADC value was largest between benign and malignant lesions. Slow ADC values of both benign and malignant lesions were significantly less than the Fast ADC values [benign:Slow ADC value=(1.83±0.86)×10-3 mm2/s, Fast ADC value=(16.95±8.63)×10-3 mm2/s; malignant: Slow ADC value=(1.05±0.31)×10-3 mm2/s, Fast ADC value=(15.12±9.90)×10-3 mm2/s] (t=-10.40,-6.29;P<0.01). Conclusion Double exponential decay model is capable of differentiating benign and malignant pelvic tumors, thus is of great significance for clinical preoperative diagnosis.

The infection rate of AIDS among the supervised persons in the supervision places is high, thus the work-ers’ chance of getting into contact with HIV infected persons or AIDS patients increases and the risk of having occupa-tional exposure gets larger. Through introducing the common situation, risk factors and preventative treatment measures, this paper explores the effective preventative countermeasures and suggests to enhance the management of HIV infected supervised persons, increase the establishment of AIDS occupational exposure protection facilities, strengthen occupa-tional safety education, improve the workers’ protection knowledge and skills and take proper treatment measures after exposure in order to reduce occupational hazards.

Objective:To investigate the effect of a degradable high-purity magnesium screw in fixing the greater trochanter bone flap of a lateral circumflex femoral artery transverse branch in the treatment of ischemic necrosis of femoral head in young and middle-aged adults.Methods:From February 2017 to February 2019, 12 cases (15 hips) of young and middle-aged patients with avascular necrosis of femoral head were treated in the Department of Orthopaedic of Affiliated Zhongshan Hospital of Dalian University. The age of patients was 30-53 years old. According to Association Research Circulation Osseous (ARCO), 2 hips were graded in stage II b, 4 in ARCO II c, 1 in ARCO III a, 5 in ARCO III b, 2 in ARCO III c and 1 in ARCO IV. The greater trochanter bone flap with a lateral circumferential vascular branch was used to fill the necrotic area, and fixed by a biodegradable high purity magnesium screw in the bone flap transfer. At 3, 6 and 12 months postoperation, the patient came to the hospital outpatient clinic for follow-up, and then were reviewed once a year. Imaging efficacy was evaluated by comparing preoperative and postoperative imaging. The Harris score and Visual Anoalogue Scale (VAS) score were tested at 12 and 24 months after surgery. The Harris score and VAS score before and after surgery were compared by Friedman test, and P<0.05 was considered statistically significant. Results:All 12 patients (15 hips) were entered in the 24-36 months of follow-up. At 12 and 24 months after surgery, Harris score was found at 87 (86, 92) and 90 (87, 92) respertively, which were both higher than that before surgery [59 (52, 74)] with a significant statistical difference ( Z=-3.743, Z=-4.473, P<0.05). However, there was no significant difference in Harris scores between 12 and 24 months after the surgery ( Z=-0.730, P>0.05). At the 12 and 24 months after surgery, VAS score was found at 3 (2, 3) and 2 (1, 3) respertively, which were both lower than that before surgery [6 (5, 6) ] with a significant statistical difference ( Z=-3.560, Z=-4.656, P<0.05). There was no statistical difference in VAS scores between 12 and 24 months after surgery ( Z=-1.095, P>0.05). X-ray and CT scan showed that the bone flaps healed well and the areas of osteonecrosis were repaired. Thirteen femoral heads were in good shape, and 2 femoral heads had further collapse of hips. No patients underwent joint replacement surgery at the time of last follow-up. Conclusion:Fixation of the greater trochanter flap of lateral circumflex femoral artery transverse branch with a degradable high-purity magnesium screw can ensure the healing of the flap at the implantation site and avoid the displacement and shedding of the flap. It is a new therapeutic option to treat the avascular necrosis of femoral head of young and middle-aged people.