Quantitative myocardial perfusion magnetic resonance imaging: the impact of pulsatile flow on contrast agent bolus dispersion.

Myocardial blood flow (MBF) can be quantified using T1-weighted first-pass magnetic resonance imaging (MRI) in combination with a tracer-kinetic model, like MMID4. This procedure requires the knowledge of an arterial input function which is usually estimated from the left ventricle (LV). Dispersion of the contrast agent bolus may occur between the LV and the tissue of interest. The aim of this study was to investigate the dispersion under conditions of physiological pulsatile blood flow, and to simulate its effect on MBF quantification. The dispersion was simulated in coronary arteries using a computational fluid dynamics (CFD) approach. Simulations were accomplished on straight vessels wit…

Extent of portal vein tumour thrombosis in patients with hepatocellular carcinoma: The more, the worse?

BACKGROUND & AIMS Portal vein tumour thrombosis (PVTT) has a significant impact on the prognosis of patients with hepatocellular carcinoma (HCC). The degree of PVTT varies from sub-/segmental invasion to complete occlusion of the main trunk. Aim of this study was to evaluate whether the degree of PVTT correlates with prognosis. METHODS A total of 1317 patients with HCC treated at our tertiary referral centre between January 2005 and December 2016 were included. PVTT was diagnosed by contrast-enhanced computed tomography or magnetic resonance imaging. The extent of PVTT was documented according to the Liver Cancer Study Group of Japan classification: Vp0 = no PVTT, Vp1 = segmental portal vei…

Maligne Leberveneninfiltration bei Patienten mit Hepatozellulärem Karzinom

Development of MR active contrast agents via Parahydrogen Induced Polarization

Parahydrogen Induced Polarization provides dramatic MR signal enhancement that can be exploited for molecular imaging. This method allows amongst others for Magnetic Resonance Imaging of 13C and 15N, which is usually constrained by the low MR sensitivity of these nuclei. By combining hydrogenation of barbiturates with parahydrogen under special experimental conditions (PASADENA under pressure) with a polarization transfer sequence we demonstrate the transfer of the initial 1H polarization to 13C. The polarization transfer yields a signal increase for 13C of more than 1000. Hence, the role of certain target compounds such as anesthetics like the barbituric acid derivatives could be investiga…

Quantitative contrast-enhanced myocardial perfusion magnetic resonance imaging: Simulation of bolus dispersion in constricted vessels

Quantification of myocardial blood flow (MBF) by means of T 1 -weighted first-pass magnetic resonance imaging(MRI) requires knowledge of the arterial input function (AIF), which is usually estimated from the left ventricle (LV). Dispersion of the contrast agent bolus may occur between the LV and the tissue of interest, which leads to systematic underestimation of the MBF. The aim of this study was to simulate the dispersion along a simplified coronary artery with different stenoses. To analyze the dispersion in vessels with typical dimensions of coronary arteries, simulations were performed using the computational fluid dynamics approach. Simulations were accomplished on straight vessels wi…