Adding liver R2* quantification to proton density fat fraction MRI of vertebral bone marrow improves the prediction of osteoporosis.

OBJECTIVES: To assess the predictive value of the combination of bone marrow (BM) proton density fat fraction (PDFF) and liver R2* for osteopenia and osteoporosis and the additional role of liver R2*. METHODS: A total of 107 healthy women were included between June 2019 and January 2021. Each participant underwent dual-energy X-ray absorptiometry (DXA) and chemical shift-encoded 3.0-T MRI. PDFF measurements were performed for each lumbar vertebral body, and R2* measurements were performed in liver segments. Agreement among measurements was assessed by Bland-Altman analysis. Receiver operating characteristic (ROC) curves were generated to select optimised cut-offs for BM PDFF and liver R2*. Univariable and multivariable logistic regressions were performed. The C statistic and continuous net reclassification improvement (NRI) were adopted to explore the incremental predictive ability of liver R2*. RESULTS: Bone mass decreased in 42 cases (39.3%) and nonbone mass decreased in 65 cases (60.7%). There were significant differences among the age groups, menopausal status groups, PDFF > 45.0% groups, and R2* > 67.7 groups. Each measurement had good reproducibility. The odds ratios (95% CIs) were 4.05 (1.22-13.43) for PDFF and 4.34 (1.41-13.35) for R2*. The C statistic (95% CI) without R2* was 0.888 (0.827-0.950), and with R2* was 0.900 (0.841-0.960). The NRI resulting from the combination of PDFF and R2* was 75.6% (p < 0.01). CONCLUSION: The predictive improvement over the use of BM PDFF and other traditional risk factors demonstrates the potential of liver R2* as a biomarker for osteopenia and osteoporosis in healthy women. KEY POINTS: • Liver R2* is a biomarker for the assessment of osteopenia and osteoporosis. • Liver R2* improved the ability to predict osteopenia and osteoporosis. • The intra- and interobserver measurements showed high agreement.

Erythropoietin reduces apoptosis of brain tissue cells in rats after cerebral ischemia/reperfusion injury: a characteristic analysis using magnetic resonance imaging.

Some in vitro experiments have shown that erythropoietin (EPO) increases resistance to apoptosis and facilitates neuronal survival following cerebral ischemia. However, results from in vivo studies are rarely reported. Perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) have been applied successfully to distinguish acute cerebral ischemic necrosis and penumbra in living animals; therefore, we hypothesized that PWI and DWI could be used to provide imaging evidence in vivo for the conclusion that EPO could reduce apoptosis in brain areas injured by cerebral ischemia/reperfusion. To validate this hypothesis, we established a rat model of focal cerebral ischemia/reperfusion injury, and treated with intra-cerebroventricular injection of EPO (5,000 U/kg) 20 minutes before injury. Brain tissue in the ischemic injury zone was sampled using MRI-guided localization. The relative area of abnormal tissue, changes in PWI and DWI in the ischemic injury zone, and the number of apoptotic cells based on TdT-mediated dUTP-biotin nick end-labeling (TUNEL) were assessed. Our findings demonstrate that EPO reduces the relative area of abnormally high signal in PWI and DWI, increases cerebral blood volume, and decreases the number of apoptotic cells positive for TUNEL in the area injured by cerebral ischemia/reperfusion. The experiment provides imaging evidence in vivo for EPO treating cerebral ischemia/reperfusion injury.

[The expression and significance of signal regulatory protein a1 in autoimmune hepatitis].

OBJECTIVE: To observe the expression change of signal regulatory protein alpha1 (SIRPalpha1) in autoimmune hepatitis (AIH) and approach the relationship between SIRPalpha1 and the extent of inflammation. METHODS: Immunohistochemistry is used to detect the expression of SIRPalpha1 in the paraffin section preparations of 33 AIH and 10 normal hepatic tissue. RESULTS: SIRPalpha1 is positive or weakly positive expressed in AIH. The staining is localized in the cytoplasm of Kupffer cells in the hepatic sinusoid with focal distribution. It is negative in normal hepatic tissue. In light AIH, it is negative or weakly positive expressed with a 36.4 percent of the positive rate (4/11). The positive or strong positive expression is found in the moderate AIH with an 84.2 percent of the positive rate(16/19). There is statistical significance between both light AIH, moderate AIH and severe AIH (P less than 0.001) and moderate AIH and light AIH (P less than 0.001). There is no statistical significance between both light AIH and severe AIH (P = 0.145 ) and moderate AIH and severe AIH (P = 0.084). CONCLUSIONS: As a negative regulatory factor, the expression of SIRPalpha1 in hepatic sinusoid Kupffer cells is some associated with the extent of AIH.

[Value of in vivo monitoring of abdominal aortic atherosclerosis by high field magnetic resonance imaging in apoE-/- mice fed a high fat diet or infused with angiotensin II].

OBJECTIVE: to explore the value of in vivo dynamic monitoring of abdominal aortic atherosclerosis (AS) by high field magnetic resonance (MR) imaging (MRI) in apoE-/- mice fed a high fat diet or infused with angiotensin. METHODS: high fat diet or angiotensin II infusion was applied to apoE-/- mice for establishment of abdominal aortic atherosclerosis model. Abdominal aorta MRI was performed at 3 time points (baseline, 3 and 6 months) in 13 high fat diet fed apoE-/- mice aged 10-12 months and 3 wild-type control mice; 10 apoE-/- mice aged 6 months were infused with angiotensin II (1000 or 500 ng × kg(-1)× min(-1), n = 5 each) or saline for 14 d through Osmotic minipump. The abdominal aortic artery MRI was performed at baseline and 14 d after infusion. Black blood sequences of FLASH T1 weighted images and Proton density weighted-T2 weighted dual echo images were obtained. At each observation time post MRI, mice (n = 3, 5 and 5 for high fat diet group and n = 5 and 5 for angiotensin II infusion group) were sacrificed for pathological examination of the abdominal artery. RESULTS: (1) the abdominal aorta atherosclerosis was identified in both high fat diet and angiotensin II treated apoE-/- mice but in WT controls. Lesion progression was documented in high fat diet fed apoE-/- mice characterized by significantly increased vessel wall (a marker of atherosclerotic burden, F = 29.94, P < 0.05) and gradually increased plaque signal in PDW and T2W images. Results derived from MRI corresponded histopathology findings in high fat diet fed apoE-/- mice (correlative coefficient = 0.84, 0.95, 0.90, P < 0.05, respectively). Both MRI and histology showed increased lipid composition and decreased fibrotic composition in these mice. (2) The vessel wall area increased significantly [(1.21 ± 0.21) mm(2) vs. (2.65 ± 0.48) mm(2), P < 0.05] and the abdominal aortic dissection aneurysms was identified in apoE-/- mice infused with high angiotensin II. The vessel wall area also increased [(0.85 ± 0.11) mm(2) vs. (1.01 ± 0.17) mm(2), P < 0.05] in low angiotensin II infused apoE-/- mice and the coefficient between MR and histopathology is 0.934. CONCLUSION: abdominal aortic unstable plaque model could be established by both high fat diet and angiotensin II infusion in apoE mice, angiotensin II infusion can transiently accelerate the progression of AS and can induce abdominal aortic dissection. Serial MR black blood sequences could demonstrate the development and progression of atherosclerosis in mouse abdominal aorta with excellent agreement to histopathology finding in terms of atherosclerotic burden and plaque composition. Thus, MRI appears to be a useful tool for in vivo AS plaque dynamic monitoring in mice.