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Background Children with advanced chronic kidney disease (CKD) frequently develop left ventricular (LV) hypertrophy. The extent of hypertrophy that results in cardiac dysfunction is unknown. Systolic function, routinely determined by ejection fraction (EF), is usually preserved in these patients. However, a decrease in EF represents an advanced cardiac dysfunction. We used cardiac magnetic resonance (CMR) and phosphorus-31 MR spectroscopy (31P MRS) to assess markers of cardiac dysfunction in young CKD patients. Methods Ten dialysis and ten post-transplant patients completed the study. The outcomes were peak LV myocardial circumferential strain (Ecc); myocardial T2 relaxation time and full width at half maximum (FWHM) of T2 distribution; and phosphocreatinine/adenosine triphosphate (PCr/ATP) to measure muscle energy metabolism. Healthy controls were used for comparison. Results All patients had normal EF; nine (45%) had low Ecc. Ecc was lower in dialysis versus transplant (p Conclusion Young patients with advanced CKD and normal EF have early cardiac changes. Association of these abnormalities with increased left ventricular mass (LVM) index suggests development of maladaptive hypertrophy. Keywords Cardiac MRI, Children, Chronic kidney Disease, Dialysis, Transplant, Cardiovascular, Introduction In adults, a strong association between chronic kidney disease (CKD) and cardiovascular disease (CVD), termed cardiorenal syndrome, is well known [1]. The cardiorenal syndrome frequently manifests as left ventricular [...]

Characterization of high-intensity focused ultrasound (HIFU) systems using ex vivo tissues is an important part of the preclinical testing for new HIFU devices. In ex vivo characterization, the lesion volume produced by the absorption of HIFU energy is quantified as operational parameters are varied. This paper examines the three methods used for lesion-volume quantification: histology, magnetic resonance (MR) imaging, and numerical calculations. The methods were studied in the context of a clinically relevant problem for HIFU procedures--that of quantifying the change in the lesion volume with changing sonication time. The lesion volumes of sonicated samples of porcine liver were determined using the three methods, at focal intensities ranging from 800 W/[cm.sup.2] to 1700 W/[cm.sup.2] and sonication times between 20 s and 40 s. It was found that histology consistently yielded lower lesion volumes than the other two methods, and the calculated values were below magnetic resonance imaging (MRI) at high applied energies. Still the three methods agreed with each other to within a [+ or -] 10% difference for all of the experiments. Increasing the sonication time produced much larger changes in the lesion volume than increasing the acoustic intensity, for the same total energy expenditure, at lower energy (less than 1000 J) levels. At higher energy levels, (around 1500 J), increasing the sonication time and increasing the intensity produced roughly the same change in the lesion volume for the same total energy expenditure. [DOI: 10.1115/1.4001739] Keywords: HIFU, MRL lesion size, sonication time, histology

Following myocardial infarction, nonischemic myocyte death results in infarct expansion, myocardial loss, and ventricular dysfunction. Here, we demonstrate that a specific proapoptotic gene, Bnip3, minimizes ventricular remodeling in the mouse, [...]

Steady-state free precision techniques are often used in cine cardiac MRI, but are highly susceptible to off-resonance artifacts. In this article, we review the types and prevalence of off-resonance artifacts in the left ventricle on a 3 T MR scanner and describe the implementation of a technique to mitigate these artifacts. A group of 16 healthy children underwent SSFP cine imaging in the short axis. The synthesizer frequency was adjusted after scouting for the optimal frequency in a series of SSFP images with different frequency shifts. A total of 136 short-axis slices were examined for artifacts after the frequency adjustment. A significant number of slices in the apex region contained dark bands, flow artifacts and/or bright out-of-plane coherent artifacts. However, only five slices (3.6%) had artifacts that were detrimental to the accurate detection of myocardial boundaries. This technique offers a fast and easy way to suppress off-resonance artifacts in SSFP imaging at 3 T. Keywords SSFP * True FISP * 3 Tesla * Cardiac MRI * Off-resonance * Artifacts