Zien Zhou

Association of Positive Airway Pressure With Cardiovascular Events and Death in Adults With Sleep Apnea: A Systematic Review and Meta-analysis

Importance Sleep apnea (obstructive and central) is associated with adverse cardiovascular risk factors and increased risks of cardiovascular disease. Positive airway pressure (PAP) provides symptomatic relief, whether delivered continuously (CPAP) or as adaptive servo-ventilation (ASV), but the associations with cardiovascular outcomes and death are unclear. Objective To assess the association of PAP vs control with cardiovascular events and death in patients with sleep apnea. Data Sources and Study Selection MEDLINE, EMBASE, and the Cochrane Library were systematically searched from inception date to March 2017 for randomized clinical trials that included reporting of major adverse cardiovascular events or deaths. Data Extraction and Synthesis Two authors independently extracted data using standardized forms. Summary relative risks (RRs), risk differences (RDs) and 95% CIs were obtained using random-effects meta-analysis. Main Outcomes and Measures The main outcomes were a composite of acute coronary syndrome (ACS) events, stroke, or vascular death (major adverse cardiovascular events); cause-specific vascular events; and death. Results The analyses included data from 10 trials (9 CPAP; 1 ASV) of patients with sleep apnea (N = 7266; mean age, 60.9 [range, 51.5 to 71.1] years; 5847 [80.5%] men; mean [SD] body mass index, 30.0 [5.2]. Among 356 major adverse cardiovascular events and 613 deaths recorded, there was no significant association of PAP with major adverse cardiovascular events (RR, 0.77 [95% CI, 0.53 to 1.13]; P = .19 and RD, −0.01 [95% CI, −0.03 to 0.01]; P = .23), cardiovascular death (RR, 1.15 [95% CI, 0.88 to 1.50]; P = .30 and RD −0.00 [95% CI, −0.02 to 0.02]; P = .87), or all-cause death (RR, 1.13 [95% CI, 0.99 to 1.29]; P = .08 and RD, 0.00 [95% CI, −0.01 to 0.01]; P = .51). The same was true for ACS, stroke, and heart failure. There was no evidence of different associations for CPAP vs ASV (all P value homogeneity >.24), and meta-regressions identified no associations of PAP with outcomes for different levels of apnea severity, follow-up duration, or adherence to PAP (all P values > .13). Conclusions and Relevance The use of PAP, compared with no treatment or sham, was not associated with reduced risks of cardiovascular outcomes or death for patients with sleep apnea. Although there are other benefits of treatment with PAP for sleep apnea, these findings do not support treatment with PAP with a goal of prevention of these outcomes.

Stroke assessment with intravoxel incoherent motion diffusion‐weighted MRI

Intravoxel incoherent motion (IVIM) diffusion‐weighted MRI can simultaneously measure diffusion and perfusion characteristics in a non‐invasive way. This study aimed to determine the potential utility of IVIM in characterizing brain diffusion and perfusion properties for clinical stroke. The multi‐b‐value diffusion‐weighted images of 101 patients diagnosed with acute/subacute ischemic stroke were retrospectively evaluated. The diffusion coefficient D, representing the water apparent diffusivity, was obtained by fitting the diffusion data with increasing high b‐values to a simple mono‐exponential model. The IVIM‐derived perfusion parameters, pseudodiffusion coefficient D*, vascular volume fraction f and blood flow‐related parameter fD*, were calculated with the bi‐exponential model. Additionally, the apparent diffusion coefficient (ADC) was fitted according to the mono‐exponential model using all b‐values. The diffusion parameters for the ischemic lesion and normal contralateral region were measured in each patient. Statistical analysis was performed using the paired Student t‐test and Pearson correlation test. Diffusion data in both the ischemic lesion and normal contralateral region followed the IVIM bi‐exponential behavior, and the IVIM model showed better goodness of fit than the mono‐exponential model with lower Akaike information criterion values. The paired Student t‐test revealed significant differences for all diffusion parameters (all P < 0.001) except D* (P = 0.218) between ischemic and normal areas. For all patients in both ischemic and normal regions, ADC was significantly positively correlated with D (both r = 1, both P < 0.001) and f (r = 0.541, P < 0.001; r = 0.262, P = 0.008); significant correlation was also found between ADC and fD* in the ischemic region (r = 0.254, P = 0.010). For all pixels within the region of interest from a representative subject in both ischemic and normal regions, ADC was significantly positively correlated with D (both r = 1, both P < 0.001), f (r = 0.823, P < 0.001; r = 0.652, P < 0.001) and fD* (r = 0.294, P < 0.001; r = 0.340, P < 0.001). These findings may have clinical implications for the use of IVIM imaging in the assessment and management of acute/subacute stroke patients. Copyright

In Ovo Monitoring of Smooth Muscle Fiber Development in the Chick Embryo: Diffusion Tensor Imaging with Histologic Correlation

Background Magnetic resonance imaging is a noninvasive method of evaluating embryonic development. Magnetic resonance diffusion tensor imaging, which is based on the measuring the directional diffusivity of water molecules, is an established method of evaluating tissue structure. Prolonged imaging times have precluded the use of embryonic diffusion tensor imaging due to motion artifact. Using temperature-based motion suppression, we aimed to investigate whether diffusion tensor imaging can be used to monitor embryonic smooth muscle development in ovo, and to determine the correlation between histologically-derived muscle fiber fraction, day of incubation and diffusion tensor imaging fractional anisotropy values and length of tracked fibers. Methodology/Principal Findings From a set of 82 normally developing fertile chicken eggs, 5 eggs were randomly chosen each day from incubation days 5 to 18 and cooled using a dual-cooling technique prior to and during magnetic resonance imaging at 3.0 Tesla. Smooth muscle fibers of the gizzard were tracked using region of interests placed over the gizzard. Following imaging, the egg was cracked and the embryo was fixated and sectioned, and a micrograph most closely corresponding to the acquired magnetic resonance image was made. Smooth muscle fiber fraction was determined using an automated computer algorithm. Conclusions/Significance We show that diffusion tensor images of smooth muscle within the embryonic gizzard can be acquired in ovo from incubation day 11 through hatching. Length of tracked fibers and day of incubation were found to have statistical significance (p<0.05) by multiple linear regression correlation with histologic specimens of sacrificed embryos from day 11 of incubation through hatching. The morphologic pattern of development in our histologic specimens corresponds to the development of embryonic gizzard as reported in the literature. These results suggest that diffusion tensor imaging can provide a noninvasive method of evaluating in ovo development of smooth muscle tissue.

In ovo serial skeletal muscle diffusion tractography of the developing chick embryo using DTI: feasibility and correlation with histology

BackgroundMagnetic resonance imaging is a noninvasive method of evaluating embryonic development. Diffusion tensor imaging (DTI), based on the directional diffusivity of water molecules, is an established method of evaluating tissue structure. Yet embryonic motion degrades the in vivo acquisition of long-duration DTI. We used a dual-cooling technique to avoid motion artifact and aimed to investigate whether DTI can be used to monitor chick embryonic skeletal muscle development in ovo, and to investigate the correlation between quantitative DTI parameters fractional anisotropy (FA) and fiber length and quantitative histologic parameters fiber area percentage (FiberArea%) and limb length.ResultsFrom 84 normally developing chick embryos, 5 were randomly chosen each day from incubation days 5 to 18 and scanned using 3.0 Tesla magnetic resonance imaging. A dual-cooling technique is used before and during imaging. Eggs were cracked for making histological specimen after imaging. 3 eggs were serially imaged from days 5 to 18. We show that skeletal muscle fibers can be tracked in hind limb in DTI beginning with incubation day 8. Our data shows a good positive correlation between quantitative DTI and histologic parameters (FA vs FiberArea%: r= 0.943, p<0.0001; Fiber_length vs Limb_length: r=0.974, p<0.0001). The result of tracked fibers in DTI during incubation corresponds to the development of chick embryonic skeletal muscle as reported in the literature.ConclusionDiffusion tensor imaging can provide a noninvasive means of evaluating skeletal muscle development in ovo.

Monitoring brain development of chick embryos in vivo using 3.0 T MRI: subdivision volume change and preliminary structural quantification using DTI

BackgroundMagnetic resonance imaging (MRI) has many advantages in the research of in vivo embryonic brain development, specifically its noninvasive aspects and ability to avoid skeletal interference. However, few studies have focused on brain development in chick, which is a traditional animal model in developmental biology. We aimed to serially monitor chick embryo brain development in vivo using 3.0 T MRI.MethodsTen fertile Hy-line white eggs were incubated and seven chick embryo brains were monitored in vivo and analyzed serially from 5 to 20 days during incubation using 3.0 T MRI. A fast positioning sequence was pre-scanned to obtain sagittal and coronal brain planes corresponding to the established atlas. T2-weighted imaging (T2WI) was performed for volume estimation of the whole brain and subdivision (telencephalon, cerebellum, brainstem, and lateral ventricle [LV]); diffusion tensor imaging (DTI) was used to reflect the evolution of neural bundle structures.ResultsThe chick embryos’ whole brain and subdivision grew non-linearly over time; the DTI fractional anisotropy (FA) value within the telencephalon increased non-linearly as well. All seven scanned eggs hatched successfully.ConclusionsMRI avoids embryonic sacrifice in a way that allows serial monitoring of longitudinal developmental processes of a single embryo. Feasibility for analyzing subdivision of the brain during development, and adding structural information related to neural bundles, makes MRI a powerful tool for exploring brain development.

Feasibility of in ovo diffusion tractography in the chick embryo using a dual-cooling technique.

To evaluate the capability of a dual‐cooling technique in suppressing motion artifact and to evaluate the feasibility of the noninvasive muscle fibers tracking using DTI during chick embryonic development.

Is Regular Screening for Intracranial Aneurysm Necessary in Patients with Autosomal Dominant Polycystic Kidney Disease? A Systematic Review and Meta-analysis

Background: The prevalence of intracranial aneurysm in patients with autosomal dominant polycystic kidney disease (ADPKD) is higher than that among the general population. We performed a systematic review and meta-analysis on the prevalence and natural history of intracranial aneurysm among patients with ADPKD. Methods: Medline, Embase, Web of Science and Scopus, from inception to July 2016, were searched for studies reporting the occurrence of intracranial aneurysms among participants with ADPKD. Two authors independently assessed the eligibility of all retrieved studies and extracted data. Information on the prevalence of intracranial aneurysms and their natural history in participants with ADPKD was collected from all included studies. Results: Fifteen studies with 1,490 participants with ADPKD were pooled to study about the prevalence of intracranial aneurysm in participants with ADPKD, and the prevalence rate was found to be 10% (95% CI 7-13%). Studies from China, Japan and Europe (Germany, Poland) reported a higher prevalence of intracranial aneurysm. Having a family history of haemorrhagic stroke or intracranial aneurysm was a risk factor for aneurysm occurrence. Twenty-three percent (95% CI 15-31%) of the participants had multiple aneurysms. Most of the aneurysms were small (<6 mm) and located in the anterior circulation. Five studies with 171 participants (83 with 106 aneurysms at baseline and 88 without) were analyzed to understand the natural history of aneurysms, with an incidence of aneurysm growth, new aneurysm and aneurysm rupture of 1.84% (followed up for 435 person-years), 0.57% (1,227 person-years) and 0.13% (792 person-years) respectively. Conclusions: Screening for intracranial aneurysm is recommended in patients with ADPKD when there is a family history of haemorrhagic stroke or intracranial aneurysm and when they are from China, Japan or Europe (Germany, Poland). Based on existing data, regular imaging follow-up is not supported. High-quality, prospective studies are needed in the future.

Effectiveness and Safety of Antibiotics for Preventing Pneumonia and Improving Outcome after Acute Stroke: Systematic Review and Meta-analysis

BACKGROUND Pneumonia is a common complication after stroke which increases morbidity and mortality. This systematic review was conducted to evaluate the efficacy and safety of antibiotics for the prevention of pneumonia after acute stroke. METHODS Medline, EMBASE, and Cochrane databases were searched for randomized controlled trials comparing preventive antibiotics to placebo or no antibiotics after acute stroke. The primary outcome was poststroke pneumonia. Secondary outcomes were all infections, urinary tract infections, death, dependency, length of hospital stay, and adverse events. Treatment effects were summarized using random effects metaanalysis. RESULTS Six trials (4111 patients) were eligible for inclusion. The median National Institute of Health Stroke Scale score in included trials ranged from 5 to 16.5. The proportion of dysphagia ranged from 26% to 100%. Preventive antibiotics were commenced within 48hours after acute stroke. Compared to control, preventive antibiotics reduced the risk of poststroke pneumonia (RR .75, 95%CI ·.57-.99), and all infections (RR .58, 95%CI .48-.69). There was no significant difference in the risks of dependency (RR 0.99, 95%CI 0·80-1·11), or mortality (RR .96, 95%CI .78-1.19) between the preventive antibiotics and control groups. Preventive antibiotics did not increase the risk of elevated liver enzymes (RR 1.20, 95% CI .97-1.49). Preventive antibiotics had uncertain effects on the risks of other adverse events. CONCLUSION Preventive antibiotics reduced the risk of post-stroke pneumonia. However, there is insufficient evidence to currently recommend routine use of preventive antibiotics after acute stroke.

Resuming anticoagulants after anticoagulation-associated intracranial haemorrhage: systematic review and meta-analysis

Objective To determine the adverse outcomes following resumption of anticoagulation in patients with anticoagulation-associated intracranial haemorrhage (ICH). Design We performed a systematic review and meta-analysis in this clinical population. The Preferred Reporting Items for Systemic Reviews and Meta-Analyses statement was followed, and two authors independently assessed eligibility of all retrieved studies and extracted data. Data sources Medline, Embase and the Cochrane Central Register of Controlled Trials, from inception to February 2017. Eligibility criteria and outcomes Randomised controlled trials or cohort studies that recruited adults who received oral anticoagulants at the time of ICH occurrence and survived after the acute phase or hospitalisation were searched. Primary outcomes, including long-term mortality, recurrent ICH and thromboembolic events. Secondary outcomes were the frequency of resuming anticoagulant therapy and related factors. Results We included 12 cohort studies (no clinical trials) involving 3431 ICH participants. The pooled frequency of resuming anticoagulant therapy was 38% (95% CI 32% to 44%), but this was higher in participants with prosthetic heart valves, subarachnoid haemorrhage or dyslipidaemia. There was no evidence that resuming anticoagulant therapy was associated with higher long-term mortality (pooled relative risk (RR) 0.60, 95% CI 0.30 to 1.19; p=0.14) or ICH recurrence (pooled RR 1.14, 95% CI 0.72 to 1.80; p=0.57). Resumption of anticoagulation was associated with significantly fewer thromboembolic events (pooled RR 0.31, 95% CI 0.23 to 0.42; p<0.001). In a subgroup of patients with atrial fibrillation, resuming anticoagulant therapy was associated with fewer long-term mortality (pooled RR 0.27, 95% CI 0.20 to 0.37, p<0.001). Conclusions Based on these observational studies, resuming anticoagulant therapy after anticoagulation-associated ICH has beneficial effects on long-term complications. Clinical trials are needed to substantiate these findings. PROSPERO registration number CRD42017063827.

Evaluation of carotid plaque vulnerability in vivo: Correlation between dynamic contrast-enhanced MRI and MRI-modified AHA classification

To noninvasively monitor carotid plaque vulnerability by exploring the relationship between pharmacokinetic parameters (PPs) of dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) and plaque types based on MRI‐modified American Heart Association (AHA) classification, as well as to assess the ability of PPs in discrimination between stable and vulnerable plaques suspected on MRI.