Quantitative perfusion-CMR is significantly influenced by the placement of the arterial input function

The aim of this study is to provide a systematic assessment of the influence of the position on the arterial input function (AIF) for perfusion quantification. In 39 patients with a wide range of left ventricular function the AIF was determined using a diluted contrast bolus of a cardiac magnetic resonance imaging in three left ventricular levels (basal, mid, apex) as well as aortic sinus (AoS). Time to peak signal intensities, baseline corrected peak signal intensity and upslopes were determined and compared to those obtained in the AoS. The error induced by sampling the AIF in a position different to the AoS was determined by Fermi deconvolution. The time to peak signal intensity was strongly correlated (r2 > 0.9) for all positions with a systematic earlier arrival in the basal (− 2153 ± 818 ms), the mid (− 1429 ± 928 ms) and the apical slice (− 450 ± 739 ms) relative to the AoS (all p < 0.001). Peak signal intensity as well as upslopes were strongly correlated (r2 > 0.9 for both) for all positions with a systematic overestimation in all positions relative to the AoS (all p < 0.001 and all p < 0.05). Differences between the positions were more pronounced for patients with reduced ejection fraction. The error of averaged MBF quantification was 8%, 13% and 27% for the base, mid and apex. The location of the AIF significantly influences core parameters for perfusion quantification with a systematic and ejection fraction dependent error. Full quantification should be based on obtaining the AIF as close as possible to the myocardium to minimize these errors.

Signal Intensity of Contrast Enhancement according to TE in 3.0T MRI T1 Imaging

Normal body tissue or lesion characteristics in T1 images have been evaluated; however, how external parameters effect the change in signal intensity by gadolinium-based contrast agent remains unknown. We investigated how contrast enhancement changed according to echo time (TE) in 3.0T magnetic resonance (MR) T1 imaging and determined the optimal settings for TE in contrast-enhanced T1 imaging. Since there are no guidelines regarding parameters for T1 enhancement when using MR-contrast agents, we analyzed results from varying TEs (between 25 and 7 msec) in both a phantom and clinical study. We obtained the following results: contrast percentage of fat to saline increased from 740.0–1003.6%, response start point increased from 30–90 mmol, max peak signal intensity increased from 1771–2425 a.u., max peak point increased from 2–4 mmol, enhancement percentage of the max peak signal intensity (MPSI) to saline increased from 1671.0–2065.2%, the average of SI on each mol as TE increased from 600.8–996.6 a.u., the average of SI as TE on each molar concentration increased from 378–845 a.u., the AEPSS increased from 44.3–140.3%, and the AEPSC increased from 224.3–647.8%. We confirmed that TE can affect contrast enhancement, and the lowest TE has faster and higher effects on contrast enhancement.

Sensitive and Selective Detection of Paramagnetic Species Using Cavity Enhanced Magneto-Optic Rotation

Cavity enhanced magneto-optic rotation spectroscopy (CEMOR) is a technique that utilizes a high-finesse cavity within a traditional magnetic rotation experimental setup to realize the benefits of both cavity ringdown and magneto-optic methods simultaneously. By observing Ga atoms at their resonance line of 417.204 nm, we demonstrate that CEMOR allows selective detection of paramagnetic species with lower detection limits than can be obtained through either flame atomic absorption or magnetic rotation spectroscopies. Quantitative CEMOR measurements of Ga in an air–acetylene flame reveal a 105 sensitivity increase over conventional flame atomic absorption in our experimental setup. Sample concentration is shown to impact the temporal behavior of transmitted signals, resulting in a significant time shift in transmission of peak signal intensity. Such time shifting has not been theoretically predicted, and we report its first experimental demonstration. The work discussed herein suggests that the CEMOR technique can be used to simplify the study of species such as combustion-generated radicals, which often absorb weakly and occur in spectral regions crowded by stronger molecular absorption lines.