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The study compared the net decline of intramyocellular lipids (IMCL) during exercise (n = 18) measured by biochemical assay (BIO) and Oil Red O (ORO) staining on biopsy samples from vastus lateralis muscle and by [sup.1]H-MR spectroscopy (MRS) sampled in an 11 x 11 x 18-[mm.sup.3] voxel in the same muscle. IMCL was measured before and after a 2-h cycling bout (~75% [VO.sub.2] peak). ORO and MRS measurements showed substantial IMCL use during exercise of 31 [+ or -] 12 and 47 [+ or -] 6% of preexercise IMCL content. In contrast, use of BIO for IMCL determination did not reveal an exercise-induced breakdown of IMCL (2 [+ or -] 9%, P = 0.29) in young healthy males. Correlations between different measures of exercise-induced IMCL degradation were low. Coefficients were 0.48 for MRS vs. ORO (P = 0.07) and were even lower for BIO vs. MRS (r = 0.38, P = 0.13) or ORO (r = 0.08, P = 0.78). This study demonstrates that different methods to measure IMCL in human muscles can result in different conclusions with regard to exercise-induced IMCL changes. MRS has the advantage that it is noninvasive, however, not fiber type specific and hampered by an at least 30-min delay in measurements after exercise completion and may overestimate IMCL use. BIO is the only quantitative method but is subject to variation when biopsies have different fiber type composition. However, BIO yields lower IMCL breakdown compared with ORO and MRS. ORO has the major advantage that it is fiber type specific, and it therefore provides information that is not available with the other methods. human muscle; exercise; nuclear magnetic resonance doi:10.1152/ajpendo.00112.2007

Manganese is a vital element and cofactor of many key enzymes, but it is toxic at high levels, causing pronounced disturbances in the mammalian brain. Magnetic resonance imaging (MRI) studies using manganese ions as a paramagnetic contrast agent are often limited by the neurotoxicity of Mn2+. In this work, we have explored a new in vivo model to study Mn2+ uptake, distribution and neurotoxicity in mice by subcutaneous implantation of mini-osmotic pumps delivering MnCl2 continuously for 21 days. Fractionated injections can reduce the toxicity; however, constant administration at very low doses using osmotic pumps caused a substantial effect on the T1 contrast in MRI while reducing toxicity. Manganese-enhanced MRI documented fast but reversible Mn2+ deposition largely in glomerular and mitral cell layers of the olfactory bulb, in the CA3 area of the hippocampus, and in the gray matter of the cerebellum. Mn2+ accumulated as early as the first days after implantation, with a fast dispersal 9 days after stopping a 12-days Mn2+ exposure. Prominent Mn2+ accumulation was also seen in salivary glands and in the endocrine thyroid and posterior pituitary gland. These structures with enhanced Mn2+ accumulation correlated well with those showing high expression of the secretory pathway Ca2+/Mn2+-ATPase (SPCA1), i.e. a transporter that could take part in Mn2+ detoxification. Our new experimental model for continuous low-dosage administration of Mn2+ is an easy alternative for enhancing Mn2+-based contrast in MEMRI studies, and might provide insight into the etiology of neuropathologies resulting from chronic Mn2+ exposure in vivo. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the value of different magnetic resonance (MR) protocols to assess early tumor response to chemotherapy. We used a murine tumor model (TLT) presenting different degrees of response to three different cytotoxic agents. As shown in survival curves, cyclophosphamide (CP) was the most efficient drug followed by 5-fluorouracil (5-FU), whereas the etoposide treatment had little impact on TLT tumors. Three different MR protocols were used at 9.4 Tesla 24 h post-treatment: diffusion-weighted (DW)-MRI, choline measurement by 1H MRS, and contrast-enhanced MRI using ultrasmall iron oxide nanoparticles (USPIO) targeted at phosphatidylserine. Accumulation of contrast agent in apoptotic tumors was monitored by T2-weighted images and quantified by EPR spectroscopy. Necrosis and apoptosis were assessed by histology. Large variations were observed in the measurement of choline peak areas and could not be directly correlated to tumor response. Although the targeted USPIO particles were able to significantly differentiate between the efficiency of each cytotoxic agent and best correlated with survival endpoint, they present the main disadvantage of non-specific tumor accumulation, which could be problematic when transferring the method to the clinic. DW-MRI presents a better compromise by combining longitudinal studies with a high dynamic range; however, DW-MRI was unable to show any significant effect for 5-FU. This study illustrates the need for multimodal imaging in assessing tumor response to treatment to compensate for individual limitations. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Background: Deep learning is the state-of-the-art approach for automated segmentation of the left ventricle (LV) and right ventricle (RV) in cardiac magnetic resonance (CMR) images. However, these models have been mostly trained and validated using CMR datasets of structurally normal hearts or cases with acquired cardiac disease, and are therefore not well-suited to handle cases with congenital cardiac disease such as tetralogy of Fallot (TOF). We aimed to develop and validate a dedicated model with improved performance for LV and RV cavity and myocardium quantification in patients with repaired TOF., Methods: We trained a 3D convolutional neural network (CNN) with 5-fold cross-validation using manually delineated end-diastolic (ED) and end-systolic (ES) short-axis image stacks obtained from either a public dataset containing patients with no or acquired cardiac pathology (n=100), an institutional dataset of TOF patients (n=96), or both datasets mixed. Our method allows for missing labels in the training images to accommodate for different ED and ES phases for LV and RV as is commonly the case in TOF. The best performing model was applied to all frames of a separate test set of TOF cases (n=36) and ED and ES phases were automatically determined for LV and RV separately. The model was evaluated against the performance of a commercial software (suiteHEART®, NeoSoft, Pewaukee, Wisconsin, US)., Results: Training on the mixture of both datasets yielded the best agreement with the manual ground truth for the TOF cases, achieving a median DICE similarity coefficient of (93.8%, 89.8%) for LV cavity and of (92.9%, 90.9%) for RV cavity at (ED, ES) respectively, and of 80.9% and 61.8% for LV and RV myocardium at ED. The offset in automated ED and ES frame selection was 0.56 and 0.89 frames on average for LV and RV respectively. No statistically significant differences were found between our model and the commercial software for LV quantification (two-sided Wilcoxon signed rank test, p<5%), while RV quantification was significantly improved with our model achieving a mean absolute error of 12ml for RV cavity compared to 36ml for the commercial software., Conclusion: We developed and validated a fully automatic segmentation and quantification approach for LV and RV, including RV mass, in patients with repaired TOF. Compared to a commercial software, our approach is superior for RV quantification indicating its potential in clinical practice., Competing Interests: Competing interests The authors declare that they have no competing interests. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)