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Background: Monitoring minimally invasive thermo ablation procedures using magnetic resonance (MR) thermometry allows therapy of tumors even close to critical anatomical structures. Unfortunately, intraoperative monitoring remains challenging due to the necessary accuracy and real‐time capability. One reason for this is the statistical error introduced by MR measurement, which causes the prediction of ablation zones to become inaccurate. Purpose: In this work, we derive a probabilistic model for the prediction of ablation zones during thermal ablation procedures based on the thermal damage model CEM43. By integrating the statistical error caused by MR measurement into the conventional prediction, we hope to reduce the amount of falsely classified voxels. Methods: The probabilistic CEM43 model is empirically evaluated using a polyacrilamide gel phantom and three in‐vivo pig livers. Results: The results show a higher accuracy in three out of four data sets, with a relative difference in Sørensen–Dice coefficient from −3.04%$-3.04\%$ to 3.97% compared to the conventional model. Furthermore, the ablation zones predicted by the probabilistic model show a false positive rate with a relative decrease of 11.89%–30.04% compared to the conventional model. Conclusion: The presented probabilistic thermal dose model might help to prevent false classification of voxels within ablation zones. This could potentially result in an increased success rate for MR‐guided thermal ablation procedures. Future work may address additional error sources and a follow‐up study in a more realistic clinical context. [ABSTRACT FROM AUTHOR]

Purpose: To implement and test variants of chemical shift imaging (CSI) acquiring both free induction decays (FIDs) showing all dissolved‐phase compartments and spin echoes for specifically assessing 129$$ {}^{129} $$Xe in lipids in order to perform precise lipid‐dissolved 129$$ {}^{129} $$Xe MR thermometry in a rat model of general hypothermia. Methods: Imaging was performed at 2.89 T. T2$$ {T}_2 $$ of 129$$ {}^{129} $$Xe in lipids was determined in one rat by fitting exponentials to decaying signals of global spin‐echo spectra. Four rats (conventional CSI) and six rats (turbo spectroscopic imaging) were scanned at three time points with core body temperature 37/34/37∘$$ {}^{\circ } $$C. Lorentzian functions were fit to spectra from regions of interest to determine the water‐referenced chemical shift of lipid‐dissolved 129$$ {}^{129} $$Xe in the abdomen. Absolute 129$$ {}^{129} $$Xe‐derived temperature was compared to values from a rectal probe. Results: Global T2$$ {T}_2 $$ of 129$$ {}^{129} $$Xe in lipids was determined as 251.3 ms±81.4 ms$$ 251.3\;\mathrm{ms}\pm 81.4\;\mathrm{ms} $$. Friedman tests showed significant changes of chemical shift with time for both sequence variants and both FID and spin‐echo acquisitions. Mean and SD of 129$$ {}^{129} $$Xe and rectal probe temperature differences were found to be −0.15∘C±0.93∘C$$ -0.1{5}^{\circ}\mathrm{C}\pm 0.9{3}^{\circ}\mathrm{C} $$ (FID) and −0.38∘C±0.64∘C$$ -0.3{8}^{\circ}\mathrm{C}\pm 0.6{4}^{\circ}\mathrm{C} $$ (spin echo) for conventional CSI as well as 0.03∘C±0.77∘C$$ 0.0{3}^{\circ}\mathrm{C}\pm 0.7{7}^{\circ}\mathrm{C} $$ (FID) and −0.06∘C±0.76∘C$$ -0.0{6}^{\circ}\mathrm{C}\pm 0.7{6}^{\circ}\mathrm{C} $$ (spin echo) for turbo spectroscopic imaging. Conclusion: 129$$ {}^{129} $$Xe MRI using conventional CSI and turbo spectroscopic imaging of lipid‐dissolved 129$$ {}^{129} $$Xe enables precise temperature measurements in the rat's abdomen using both FID and spin‐echo acquisitions with acquisition of spin echoes enabling most precise temperature measurements. [ABSTRACT FROM AUTHOR]

We have previously shown that total knockout of fibroblast growth factor‐2 (FGF‐2) results in prolonged survival and improved motor performance in superoxide dismutase 1 (SOD1G93A) mutant mice, the most widely used animal model of the fatal adult onset motor neuron disease amyotrophic lateral sclerosis (ALS). Moreover, we found differential expression of growth factors in SOD1G93A mice, with distinct regulation patterns of FGF‐2 in spinal cord and muscle tissue. Within the present study we aimed to characterize FGF‐2‐isoform specific effects on survival, motor performance as well as gene expression patterns predominantly in muscle tissue by generating double mutant SOD1G93AFGF‐2 high molecular weight‐ and SOD1G93AFGF‐2 low molecular weight‐knockout mice. While isoform specific depletion was not beneficial regarding survival or motor performance of double mutant mice, we found isoform‐dependent differential gene expression of epidermal growth factor (EGF) in the muscle of SOD1G93AFGF‐2 low molecular weight knockout mice compared to single mutant SOD1G93A mice. This significant downregulation of EGF in the muscle tissue of double mutant SOD1G93AFGF‐2 low molecular weight knockout mice implies that FGF‐2 low molecular weight knockout (or the presence of the FGF‐2 high molecular weight isoform) selectively impacts EGF gene expression in ALS muscle tissue. [ABSTRACT FROM AUTHOR]

Objective: Several findings support the concept that sensorimotor integration is disturbed in Parkinson's disease (PD) and in levodopa-induced dyskinesias. In this study, we explored the neuronal firing activity of excitatory pyramidal cells and inhibitory interneurons in the forelimb region of the primary somatosensory cortex (S1FL-Ctx), along with its interaction with oscillatory activity of the primary motor cortex (MCtx) in 6-hydroxydopamine lesioned hemiparkinsonian (HP) and levodopa-primed dyskinetic (HP-LID) rats as compared to controls. Further, gene expression patterns of distinct markers for inhibitory GABAergic neurons were analyzed in both cortical regions. Methods: Single unit activity and local field potential were recorded under urethane (1.4 g/kg, i.p) anesthesia by using quartz coated micro-electrode. Additionally, an electrocorticogram (ECoG) was acquired via a 1 mm diameter jeweller's screw, positioned on the dura mater above the MCtx ipsilateral to the 6-OHDA lesioned hemisphere. Results: While firing frequency and burst activity of S1FL-Ctx inhibitory interneurons were reduced in HP and HP-LID rats, measures of irregularity were enhanced in pyramidal cells. Further, enhanced coherence of distinct frequency bands of the theta/alpha, high-beta, and gamma frequency, together with enhanced synchronization of pyramidal cells and interneurons with MCtx oscillatory activity were observed. While GABA level was similar, gene expression levels of interneuron and GABAergic markers in S1FL-Ctx and MCtx of HP-LID rats differed to some extent. Conclusion: Our study shows both electrophysiological alterations and changes in gene expression in the sensorimotor cortices in a rat model of PD, which differ depending on the functional state after dopamine depletion and treatment indicating maladaptive neuroplasticity. [ABSTRACT FROM AUTHOR]

Objective: In Parkinson's disease (PD) patients and in 6-hydroxy- dopamine (6-OHDA) lesioned rats, the loss of dopaminergic (DA) neurons in the substantia nigra pars compacta and the resulting DA depletion in the striatum lead to altered neuronal activity and enhanced beta activity in regions of the direct and indirect pathway of basal ganglia. Intrastriatal graft implantation of DA neurons has been shown to re-innervate the host brain and restore DA input. Methods: Female Sprague Dawley rats with 6-OHDA lesions were transplanted with cells derived from the mesencephalon of E12 rat embryos in the striatum. 6-OHDA lesioned and naïve rats served as controls. Thereafter, the effect of intrastriatal grafts on neuronal activity of the globus pallidus internus (GPi), the output nucleus of the basal ganglia, and the globus pallidus externus (GPe), a key region of the indirect pathway, was tested. Results: The rotational behavior induced by injection of DA agonists was alleviated after intrastriatal graft implantation. Electrophysiological extracellular recordings revealed enhanced firing rate in the entopeduncular nucleus (EPN, the equivalent to the GPi) and enhanced measures of irregularity in the globus pallidus (GP, the equivalent to the GPe). Analysis of firing patterns in 6-OHDA lesioned rats revealed reduced regular firing in both regions, which was accompanied by enhanced burst and irregular firing in the EPN and enhanced irregular firing in the GP. In both regions, intrastriatal DA grafts normalized altered firing activity. Analysis of oscillatory activity revealed enhanced beta activity in both regions, which were reduced by intrastriatal DA grafts. Discussion: In summary, DA grafts compensate functional deficits and neuronal activity of the basal ganglia indirect and direct pathway. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to evaluate the impact of a prototype grid with a 29:1 ratio (r29) and a 15:1 (r15) grid on the image quality (IQ) and radiation dose in abdominal angiography., Materials and Methods: Six typical abdominal angiographic image scenarios were created in 4 pigs. Polymethylmethacrylate and aluminum plates were used to add 10 cm of patient equivalent thickness to simulate different body types. Fluoroscopic images were acquired with a source-to-image receptor distance of 120 cm. Tantalum- and iron-specific acquisition protocols at different IQ levels were acquired. IQ of radiation dose equivalent image pairs, created with the r29 and r15 grids, respectively, was quantitatively evaluated using contrast-to-noise ratio (CNR) measurements. Differences in radiation dose were estimated using the dose-weighted CNR. Two blinded readers compared IQ of these images using a Likert scale. In a second step, the readers selected pairs of the r29 and r15 images with subjectively equivalent IQ. Radiation doses were then compared., Results: Compared with the r15 grid, the r29 grid images achieved similar CNR at an average of 26% (±12%) lower radiation dose at a mean patient equivalent thickness of 26 cm and 36 cm. Both readers noted a significant increase in IQ (P < 0.001) for dose equivalent images, whereas the interobserver agreement was 0.59. For the selected IQ equivalent images, a radiation dose reduction of 38% (±17%; P < 0.001, interobserver agreement 0.92) was noted when using the r29 grid., Conclusions: The use of an r29 grid at a large source-to-image receptor distance can significantly improve the IQ compared with the r15 grid at the same radiation dose in abdominal angiography or can reduce radiation dose while preserving IQ., Competing Interests: Conflicts of interest and sources of funding: B.C.M. is a consultant and speaker for Siemens Healthineers GmbH. All other authors declare no conflicts of interest. This work was in part funded by Siemens Healthcare GmbH by an institutional grant. The funding sources had no involvement in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: To implement and test variants of chemical shift imaging (CSI) acquiring both free induction decays (FIDs) showing all dissolved-phase compartments and spin echoes for specifically assessing INLINEMATH Xe MR thermometry in a rat model of general hypothermia., Methods: Imaging was performed at 2.89 T. INLINEMATH Xe-derived temperature was compared to values from a rectal probe., Results: Global INLINEMATH (spin echo) for turbo spectroscopic imaging., Conclusion: INLINEMATH Xe enables precise temperature measurements in the rat's abdomen using both FID and spin-echo acquisitions with acquisition of spin echoes enabling most precise temperature measurements., (© 2022 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)