ADC values determined from 1.5 T MR DWI of benign and malignant ovarian masses were found to be significantly different.

Several models have been proposed to describe the tectonic evolution of SE Tibet and its marginal areas. Hence, high-resolution crustal velocity models are essential to address this controversy. With waveform data from 73 broadband stations in southwest China and northern Vietnam, we invert for a 3-D shear wave velocity model of the crust and uppermost mantle from ambient noise tomography. Our model reveals that the midlower crustal low-velocity zone in the Xiaojiang Fault Zone extends farther southward across the Red River Fault to Vietnam and is approximately bounded by the Xiaojiang and Dien Bien Phu faults to the east. We suggest that the observed low-velocity zone represents a mechanically weak zone in the mid-lower crust, which may serve as a channel for efficient southward material transport in SE Tibet. With our results and previous evidence, we propose a combined model that integrates rigid block extrusion and crustal channel flow to describe the large-scale material transport in SE Tibet. We further propose a two-phase material transport model in SE Tibet after the India-Eurasia plate collision: (1) rigid block extrusion between the right-lateral Sagaing Fault and left-lateral Red River Fault during the early Oligocene-early Miocene and (2) a combined model of rigid block extrusion and material channel flow in the mid-lower crust from the late Miocene to the present. The southward crustal material transport is likely to be diverted along two major channels around the more rigid crust beneath the inner zone of the Emeishan large igneous province.

Objective The objective of this study was to investigate the diagnostic discordance of osteoporosis by quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) in Chinese elderly men. Methods A total of 313 males older than 60 years, who underwent both spinal QCT and lumbar spine and hip DXA in our department, were included. The diagnostic criteria established by the World Health Organisation in 1994 were used for DXA to diagnose osteoporosis, and the criteria recommended by the International Society of Clinical Densitometry were used for QCT. The osteoporosis detection rate by the two techniques was calculated, and the difference was compared. The minor discordance was considered present when the different diagnostic classes between the two techniques were adjacent. Major discordance was present when the diagnosis by one technique was osteoporosis and the other was normal. The computed tomography images were reviewed by radiologists to assess whether vertebral fracture, aorta calcification or degeneration was present. Results In the 313 participants (mean age, 79.6 ± 7.2 years), the osteoporosis detection rate was 10.9% for DXA (lumbar spine and hip) and 45.1% for QCT, a significant difference ( p < 0.001). The major discordance, minor discordance and concordance of diagnosis between the two techniques were seen in 8.3%, 50.8% and 40.9%, respectively. QCT detected osteoporosis better than DXA. The causes of this discordance were degeneration of spine, abdominal aorta calcification and vertebral fractures. Conclusion Our study demonstrated that discordance was common when using QCT and DXA to diagnose osteoporosis and that spinal degeneration, aorta calcification and fracture obscure the bone mineral density measurement of spine by DXA. QCT is a more sensitive method of choice to identify osteoporosis in elderly Chinese men. The translational potential of this article This study investigated the diagnostic discordance of osteoporosis by quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) in Chinese elderly men. The results demonstrated that QCT is a more sensitive method of choice to identify osteoporosis in elderly Chinese men. This work may help clinicians make an appropriate choice of technique for the accurate diagnosis of osteoporosis and identify the patients at high risk of osteoporosis who should be treated early to prevent fractures. This may influence the therapeutic plan and the overall prognosis of patients.

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