Role of quantitative magnetic resonance imaging parameters in the evaluation of treatment response in malignant tumors / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To elaborate the role of quantitative magnetic resonance imaging (MRI) parameters in the evaluation of treatment response in malignant tumors.</p><p><b>DATA SOURCES</b>Data cited in this review were obtained mainly from PubMed in English from 1999 to 2014, with keywords "dynamic contrast-enhanced (DCE)-MRI," "diffusion-weighted imaging (DWI)," "microcirculation," "apparent diffusion coefficient (ADC)," "treatment response" and "oncology."</p><p><b>STUDY SELECTION</b>Articles regarding principles of DCE-MRI, principles of DWI, clinical applications as well as opportunity and aspiration were identified, retrieved and reviewed.</p><p><b>RESULTS</b>A significant correlation between ADC values and treatment response was reported in most DWI studies. Most quantitative DCE-MRI studies showed a significant correlation between K trans values and treatment response. However, in different tumors and studies, both high and low pretreatment ADC or K trans values were found to be associated with response rate. Both DCE-MRI and DWI demonstrated changes in their parameters hours to days after treatment, showing a decrease in K trans or an increase in ADC associated with response in most cases.</p><p><b>CONCLUSIONS</b>Combinations of quantitative MRI play an important role in the evaluation of treatment response of malignant tumors and hold promise for use as a cancer treatment response biomarker. However, validation is hampered by the lack of reproducibility and standardization. MRI acquisition protocols and quantitative image analysis approaches should be properly addressed prior to further testing the clinical use of quantitative MRI parameters in the assessment of treatments.</p>

Research progress in HIV auxiliary proteins counteracting host restriction factors / 病毒学报

Identification and functional analyses of antiviral restriction factors in hosts have become hot research topics. Four HIV restriction factors, APOBEC3G, Trim5alpha, Tetherin, and SAMHD1, have been identified in recent years. By encoding auxiliary proteins, lentiviruses can counteract host restriction factors. For example, the auxiliary proteins Vif, Vpu, and Vpx of HIV antagonize APOBEC3G, Tetherin, and SAMHD1, respectively. Furthermore, these auxiliary proteins enable the entry of HIV into host cells and influence the replication and pathogenicity of HIV. In this paper, we review the research progress in the functions of the three HIV auxiliary proteins that can antagonize the host restriction factors.

Characteristic findings of malignant melanoma in the sinonasal cavity on magnetic resonance imaging / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Malignant sinonasal melanoma (MSM) is a rare tumor with a perplexing signal intensity due to variable histopathologic components. This study was undertaken to delineate its MR imaging features.</p><p><b>METHODS</b>MR imaging findings of 10 patients (6 women and 4 men, mean age 61.3 years old) with pathologically confirmed MSM were retrospectively reviewed. The location, size, signal intensity, enhancement, and internal imaging characteristics of all tumors were evaluated. Signal intensity and degree of enhancement was graded in comparison with the gray matter and adjacent muscle uptake, respectively.</p><p><b>RESULTS</b>There were 8 tumors that were pathologically confirmed to contain melanin. Compared to gray matter of the brain, 7 of them demonstrated hyperintensity on T1WI and 6 (6/7) showed hypointensity on T2WI. There was multiple linear, dark-signal intensity on T2WI within the mass in 9 of the 10 patients' tumors. Evaluated with gadolinium-enhanced imaging, all 10 patients showed moderate enhancement within the areas that were isointense in the lesion on pregadolinium T1WI. Moreover, some parts which displayed hyperintensity on T1WI within the tumors of 7 patients showed mild enhancement that was similar to muscle on a time-intensity curve (TIC).</p><p><b>CONCLUSIONS</b>MSM shows characteristic MR signal intensity (hyperintensity on T1WI and the linear, low-signal intensity on T2WI), which may provide valuable information for clinical diagnosis. Together with conventional MRI, TIC may be useful for indicating pleomorphic patterns of MSM.</p>

Detection of 100% oxygen induced changes in retina using magnetic resonance imaging: a human study / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Inner retinal oxygenation response (ΔPO(2)) is a worldwide study focus. However, the relevant reports on its radiological measurements are limited. In this study, magnetic resonance imaging (MRI), employing T1 weighted image (T1WI), was used to detect changes in ΔPO(2) following 100% oxygen inhalation in human subjects.</p><p><b>METHODS</b>MRI was performed on a 1.5-T GE scanner system. After obtaining ophthalmologic data, eleven healthy individuals were given room air and 100% oxygen inhalation in order with different intervals. The MRI T1WI data were collected for 50 minutes. Data were analyzed with NIH IMAGE software.</p><p><b>RESULTS</b>ΔPO(2) was not panretinally uniform, and changes in oxygenation response were spatially inhomogeneous. During the initial phase (before 5 minutes) of 100% oxygen inhalation, preretinal vitreous water signals in the region of papilla optica increased rapidly. On the contrary, in other regions signals declined. In a later period (35 minutes), ΔPO(2) was panretinally fluctuated and increased slowly and attained homeostasis. After hyperoxia (45 minutes), delayed-enhancement of preretinal vitreous water signals in regions other than the papilla optica occurred, and then dropped down. There was no significant difference (P > 0.05) at any consecutive time point during and after hyperoixa.</p><p><b>CONCLUSIONS</b>These results reveal that hyperoxia can induce region-specific signal changes in preretinal vitreous water. Regulatory activity of the retinal vessel network may be the mechanism during 100% oxygen inhalation. Moreover, MRI is a valuable tool for investigating ΔPO(2) and exploring the mechanism of retinal oxygenation response physiologically or pathologically in vivo.</p>