Functional CT Imaging for Myocardial Salvage in Acute Myocardial Infarction Management

Hospitalization and revascularization treatment for patients with acute myocardial infarction (AMI) is an economic burden that can be minimized by identifying patients most likely to benefit. To this end, a non-invasive imaging technique to better characterize myocardial salvage may be helpful. In this thesis work, a functional CT technique is examined to assess at-risk, infarcted, and salvageable myocardial tissue. Data was acquired on a cohort of seven pigs with induced AMI during the acute and sub-acute phases post insult. The tracer kinetic model dependent CT images were validated against both T2-TIRM images and quantitative T1-maps acquired using MRI, as well as constant infusion CT images. Extravascular contrast distribution volume (ECDV) and myocardial perfusion (MP) parameters were used to characterize the injured myocardium. Derived ECDV and MP threshold for acute phase MI in seven pigs is 0.36 ml/g and 0.44 ml/min/g, respectively. Average MP in normal, at-risk and infarcted myocardium were 0.92 0.27, 0.80 0.19, 0.30 0.08 ml/min/g, respectively. Average ECDV in normal, at-risk, and infarcted myocardium were 0.13 0.08, 0.21 0.07, 0.60 0.12 ml/g, respectively. Significance was demonstrated in both MP and ECDV measurements between infarcted myocardium and myocardium atrisk, as well as between infarcted and normal myocardium (p\u3c 0.01). Based on the area estimated using ECDV and MP, at-risk, infarcted, and salvageable myocardial tissue can be delineated

Invertibility of circulant matrices of arbitrary size

In this paper, we present sufficient conditions to guarantee the invertibility of rational circulant matrices with any given size. These sufficient conditions consist of linear combinations of the entries in the first row with integer coefficients. Our result is general enough to show the invertibility of circulant matrices with any size and arrangement of entries. For example, using these conditions, we show the invertibility of the family of circulant matrices with particular forms of integers generated by a primitive element in $\mathbb{Z}_p$. Also, using a combinatorial structure of these sufficient conditions, we show invertibility for circulant $0, 1$-matrices.Comment: 18 page

Exploration of the pathophysiological mechanisms underlying hemodialysis associated cardiac ischemic injury

Hemodialysis (HD) provides life-saving treatment in individuals with kidney failure. However, HD is associated with poor quality of life and extremely high mortality rates mainly caused by cardiovascular disease due to heart failure and sudden cardiac death. Standard pharmacological treatment developed within the non-kidney disease community are largely ineffective in HD patients because of the difference in pathophysiology of cardiovascular mortality. HD treatment causes hypotension and recurrent ischemic injury to multiple vascular beds including the heart, leading to heart failure. These injuries can be abrogated by improving the patient’s tolerability of the treatment. To apply interventions that may improve hemodynamic tolerability of HD, it is crucial to understand the mechanisms of HD-induced injury at every layer of the vasculature: the endothelial, microvasculature and macrovasculature. The purpose of this thesis was to study the endothelial and vascular dysfunction effecting tissue perfusion as a result of HD and under conditions of intradialytic exercise and alteration of dialysate sodium concentration

Caroli's Syndrome with Autosomal Recessive Polycystic Kidney Disease in a Two Month Old Infant

Caroli's syndrome is a rare congenital disorder that involves intrahepatic bile duct ectasia and congenital hepatic fibrosis, frequently seen with concomitant autosomal recessive polycystic kidney disease (ARPKD). Literature on infants with ARPKD is rare. Here, we present a case of a two month old boy who was diagnosed with Caroli's syndrome and ARPKD

Giant Magnetoelectric Effect in a Multiferroic Material with a High Ferroelectric Transition Temperature

We present a unique example of giant magnetoelectric effect in a conventional multiferroic HoMnO3, where polarization is very large (~56 mC/m2) and the ferroelectric transition temperature is higher than the magnetic ordering temperature by an order. We attribute the uniqueness of the giant magnetoelectric effect to the ferroelectricity induced entirely by the off-center displacement of rare earth ions with large magnetic moments. This finding suggests a new avenue to design multiferroics with large polarization and higher ferroelectric transition temperature as well as large magnetoelectric effects