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Diffusion MRI (dMRI) is an important imaging modality that is used extensively to diagnose and monitor diseases. dMRI measures random motion of water molecules and helps elucidate microstructural properties of tissues. Optimal diffusion encoding paradigms have been developed to reduce acquisition time, minimize artifacts, and acquire high fidelity data needed for advanced modeling of tissue properties. To further probe microstructural properties, joint diffusion-relaxometry and diffusion weighted MR fingerprinting have garnered interest. A thorough knowledge of different diffusion encoding methods is essential to accurately encode diffusion in MR experiments. Here, we review fundamental physics of diffusion encoding methods, their associated challenges, and how to address them. Advanced diffusion acquisition methods are also discussed.
ABSTRACT
Objective@#To investigate the effect of intracoronary administration of nicorandil prior to primary percutaneous coronary intervention (PPCI) on myocardial perfusion and short-term clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI).@*Methods@#A total of 158 patients with STEMI undergoing PPCI from January 2014 to December 2015 in Fuzhou General Hospital were enrolled consecutively in this prospective controlled randomized trial. Patients were assigned into three groups with random number table: the nicorandil group (patients received intracoronary administration of 6 mg nicorandil after guide wire or balloon successfully crossed the target lesion, n=53), the nitroglycerin group (patients received intracoronary administration of 300 μg nitroglycerin after after guide wire or balloon successfully crossed the target lesion, n=52) and the control group(patients received routine treatment, n=53). The primary outcomes were myocardial perfusion, including the levels of corrected TIMI frame count (cTFC), and the incidence of no reflow or slow flow after PPCI. The secondary outcomes included the incidence of major adverse cardiovascular events (MACE) during hospitalization (all-cause death, reperfusion arrhythmia within 2 hours after PPCI, angina within 24 hours after PPCI, new heart failure or worsening cardiac function, and repeat revascularization) and within 3 months of follow-up (all-cause death, nonfatal myocardial infarction, repeat revascularization, post-infarction angina, and re-hospitalization for congestive heart failure).@*Results@#The age of enrolled patients was (62.9±11.3) years old, and 130 cases (82.3%) of them were male. The median time of symptom-onset to balloon was 4.50 (3.20, 6.43) hours. There were significantly difference in cTFC immediately after PPCI((21.68±7.43)frames, (24.74±8.66)frames, and(27.06±10.40)frames), incidence of no reflow or slow flow after PPCI(5.7%(3/53), 13.5%(7/52), and 22.6%(12/53)), ST-segment resolution at 2 hours after procedure(90.6%(48/53), 84.6%(44/52), and 74.5%(38/53)), and reperfusion arrhythmia at 2 hours after procedure(15.1%(8/53), 36.6%(19/52), and 34.0%(18/53)) among the 3 groups(P<0.01 or 0.05). In the multivariate logistic regression models, intracoronary administration of nicorandil could lower the cTFC level (OR=0.17, 95%CI 0.10-0.41, P=0.001), acted as a protecting factor on lowering the incidence of no reflow or slow flow (OR=0.13, 95%CI 0.02-0.96, P=0.045) and reperfusion arrhythmia (OR=0.26, 95%CI 0.09-0.74, P=0.012), as well as facilitating the ST-segment resolution at 2 hours after procedure (OR=4.62, 95%CI 1.14-18.82, P=0.033). However, observed parameters were similar between intracoronary administration of nitroglycerin group compared with control group (all P>0.05). MACE within 3 months of follow-up were similar among the 3 groups(all P>0.05).@*Conclusion@#Intracoronary administration of nicorandil prior to balloon dilation can significantly improve the myocardial perfusion and reduce the occurrence of reperfusion arrhythmia during PPCI for STEMI, but does not affect the short-term prognosis in STEMI patients.
ABSTRACT
Objective Previous study found TGF-βpathway might be the molecular pathway influencing the prognosis of colo-rectal cancer, while it was uncertain whether Chinese population is associated with the disease.The article was to evaluate the genetic factors associated with prognosis in colorectal cancer. Methods 52 cases patients with colorectal cancer were followed-up for 36 months in our hospitals from January 2013 to August 2014.Their DNAs were extracted and stored and gene typing were carried out in 5 candidate genes to detect the association between SNPs and the prognosis in colorectal cancer. Results The results showed that within the TGF-βsignaling pathway, after adjusting for Bonferroni multiple testing, allele A of SNP rs10749971 located in gene POU2AF1 was associated with the recurrence of patients with stage III disease under additive and recessive genetic models ( HR =1.968, P=0.004;HR=2.174, P=0.010).Allele C of SNP rs961253 in the gene BMP2 could increase the recurrence risk (HR=1.992, P=0.005) and the death risk (HR=3.161, P=0.007) of patients with stage III disease under recessive genetic models.Allele A of SNP rs4464148 in SMAD7 gene could significantly decrease the death risk of patients with stage II and III colorectal cancer under dominant genetic model (HR=0.382, P=0.017;HR=0.230, P=0.006).In addition, accumulated effects of several adverse genes showed gene high risk group could increase the risk of death for patients with stage III colorectal cancer significantly ( HR=15.512, P=0.036;95%CI:1.611-149.360). Conclusion In different genetic models, SNP locus mutation within gene POU2AF1, BMP2 and SMAD7 on TGF-βpathway was associated with the prognosis of patients with colorectal cancer.With the increase of the number of unfavorable genes, the death risk increases accordingly.