Background
High blood pressure (BP) is a common risk factor for cerebral small vessel disease including white matter hyperintensity (WMH). Whether increased BP exacerbates WMH by impacting cerebral ...vascular morphologies remains poorly studied.
Purpose
To determine the relationships among high BP, cerebrovascular morphologies, and WMH in elderly individuals.
Study Type
Cohort.
Subjects
Eight hundred sixty‐three participants (54.2% female) from the Taizhou Imaging Study without clinical evidence of neurologic disorders were included in the analyses.
Field Strength/Sequence
3.0 T; time‐of‐flight magnetic resonance angiography (TOF MRA); T2 fluid‐attenuated inversion recovery (FLAIR); T1 magnetization‐prepared rapid gradient‐echo; gradient echo T2*‐weighted; diffusion tensor imaging; pulsed arterial spin labeling.
Assessment
Cerebrovascular morphologic measurements were quantified based on the TOF MRA images, including vessel density, radius, tortuosity, and branch number. WMH lesion volumes (WMHV) and WMH lesion counts (WMHC) were calculated automatically based on the T2 FLAIR images.
Statistical Tests
Multivariable linear regression analysis and path analysis with a linear single‐mediator model were employed. A P value <0.05 was considered statistically significant.
Results
Higher BP, especially diastolic BP, was significantly correlated with lower cerebrovascular density (β = −104) and lower branch numbers (β = −0.02). Although decreased tortuosity (β = −1.25) and increased radius (β = 93.8) were correlated with BP, no significant relationship of tortuosity (β = −4.6 × 10−4, P = 0.58) or radius (β = 0.03, P = 0.08) with BP in small vessels was found. The proportion of small vessels decreased as BP increased (SBP: β = −6.6 × 10−4; DBP: β = −9.0 × 10−4). Similarly, increased WMHV and WMHC were associated with decreased vessel density (volumes: β = −24, counts: β = −127), decreased tortuosity (volumes: β = −0.08, counts: β = −0.53), and increased radius (volumes: β = 12.6, counts: β = 86.6). Path analyses suggested an association between high BP and WMHs that were mediated by cerebrovascular morphologic changes.
Data Conclusion
Structural alterations of cerebral vessels induced by high BP are correlated with WMH. This result suggested that elevated BP might be one of the pathophysiological mechanisms involving in the co‐occurrence of cerebrovascular alteration and small vessel disease.
Level of Evidence: 1
Technical Efficacy Stage: 1
Purpose
The phase mismatch between odd and even echoes in EPI causes Nyquist ghost artifacts. Existing ghost correction methods often suffer from severe residual artifacts and are ineffective with ...k‐space undersampling data. This study proposed a deep learning–based method (PEC‐DL) to correct phase errors for DWI at 7 Tesla.
Methods
The acquired k‐space data were divided into 2 independent undersampled datasets according to their readout polarities. Then the proposed PEC‐DL network reconstructed 2 ghost‐free images using the undersampled data without calibration and navigator data. The network was trained with fully sampled images and applied to two‐ and fourfold accelerated data. Healthy volunteers and patients with Moyamoya disease were recruited to validate the efficacy of the PEC‐DL method.
Results
The PEC‐DL method was capable to mitigate the ghost artifacts in DWI in healthy volunteers as well as patients with Moyamoya disease. The fourfold accelerated results showed much less distortion in the lesions of the Moyamoya patient using high b‐value DWI and the corresponding ADC maps. The ghost‐to‐signal ratios were significantly lower in PEC‐DL images compared to conventional linear phase corrections, mini‐entropy, and PEC‐GRAPPA algorithms.
Conclusion
The proposed method can effectively eliminate ghost artifacts for full sampled and up to fourfold accelerated EPI data without calibration and navigator data.
Background
Gamma‐aminobutyric acid (GABA) is an inhibitory neurotransmitter in human brains, playing a role in the pathogenesis of various psychiatric disorders. Current methods have some ...non‐neglectable shortcomings and noninvasive and accurate detection of GABA in human brains is long‐term challenge.
Purpose
To develop a pulse sequence capable of selectively detecting and quantifying the 1H signal of GABA in human brains based on optimal controlled spin singlet order.
Study Type
Prospective.
Subjects/Phantom
A phantom of GABA (pH = 7.3 ± 0.1) and 11 healthy subjects (5 females and 6 males, body mass index: 21 ± 3 kg/m2, age: 25 ± 4 years).
Field Strength/Sequence
7 Tesla, 3 Tesla, GABA‐targeted magnetic resonance spectroscopy (GABA‐MRS‐7 T, GABA‐MRS‐3 T), magnetization prepared two rapid acquisition gradient echoes sequence.
Assessment
By using the developed pulse sequences applied on the phantom and healthy subjects, the signals of GABA were successfully selectively probed. Quantification of the signals yields the concentration of GABA in the dorsal anterior cingulate cortex (dACC) in human brains.
Statistical Tests
Frequency.
Results
The 1H signals of GABA in the phantom and in the human brains of healthy subjects were successfully detected. The concentration of GABA in the dACC of human brains was 3.3 ± 1.5 mM.
Data Conclusion
The developed pulse sequences can be used to selectively probe the 1H MR signals of GABA in human brains in vivo.
Evidence Level
1
Technical Efficacy Stage
1
Quantitative in-situ pH mapping of gliomas is important for therapeutic interventions, given its significant association with tumor progression, invasion, and metastasis. Although chemical exchange ...saturation transfer (CEST) offers a noninvasive way for pH imaging based on the pH-dependent exchange rate (k
), the reliable quantification of k
in glioma remains constrained due to technical challenges.
To quantify the pH of gliomas by measuring the proton exchange rate through optimized omega plot analysis.
Prospective.
Creatine and murine brain lysates phantoms, six rats with glioma xenograft model, and three patients with World Health Organization grade 2-4 gliomas.
11.7 T, 7.0 T, CEST imaging, T
-weighted (T
W) imaging, and T
-mapping.
Omega plot analysis, quasi-steady-state (QUASS) analysis, multi-pool Lorentzian fitting, amine and amide concentration-independent detection, pH enhanced method with the combination of amide and guanidyl (pH
), and magnetization transfer ratio (MTR) were utilized for pH metric quantification. The clinical outcomes were determined through radiologic follow-up and histopathological analysis.
Mann-Whitney U test was performed to compare glioma with normal tissue, and Pearson's correlation analysis was used to assess the relationship between k
and other parameters.
In vitro experiments reveal that the determined k
at 2 ppm increases exponentially with pH (creatine phantoms: k
= 106 + 0.147 × 10
; lysates: k
= 185.1 + 0.101 × 10
). Omega plot analysis exhibits a linear correlation between 1/MTR
and 1/ω
in the glioma xenografts (R
> 0.98) and glioma patients (R
> 0.99). The exchange rate in the rat glioma decreases compared to the contralateral normal tissue (349.46 ± 30.40 s
vs. 403.54 ± 51.01 s
, P = 0.025), while keeping independence from changes in concentration (r = 0.5037, P = 0.095). Similar pattern was observed in human data.
Utilizing QUASS-based, spillover-, and MT-corrected omega plot analysis for the measurement of exchange rates, offers a feasible method for quantifying pH within glioma.
NA TECHNICAL EFFICACY: Stage 1.
DNA damage elicits a cellular signaling response that initiates cell cycle arrest and DNA repair. Here, we find that DNA damage triggers a critical block in glutamine metabolism, which is required ...for proper DNA damage responses. This block requires the mitochondrial SIRT4, which is induced by numerous genotoxic agents and represses the metabolism of glutamine into tricarboxylic acid cycle. SIRT4 loss leads to both increased glutamine-dependent proliferation and stress-induced genomic instability, resulting in tumorigenic phenotypes. Moreover, SIRT4 knockout mice spontaneously develop lung tumors. Our data uncover SIRT4 as an important component of the DNA damage response pathway that orchestrates a metabolic block in glutamine metabolism, cell cycle arrest, and tumor suppression.
► DNA damage induces SIRT4 and inhibits mitochondrial glutamine metabolism ► SIRT4 is required for proper repression of glutamine metabolism after DNA damage ► SIRT4 loss promotes genomic instability ► SIRT4 represses tumor growth, and SIRT4 knockout mice develop tumors with age
Purpose
The purpose of this study is to introduce a novel design method of a shim coil array specifically optimized for whole brain shimming and to compare the performance of the resulting coils to ...conventional spherical harmonic shimming.
Methods
The proposed design approach is based on the stream function method and singular value decomposition. Eighty‐four field maps from 12 volunteers measured in seven different head positions were used during the design process. The cross validation technique was applied to find an optimal number of coil elements in the array. Additional 42 field maps from 6 further volunteers were used for an independent validation. A bootstrapping technique was used to estimate the required population size to achieve a stable coil design.
Results
Shimming using 12 and 24 coil elements outperforms fourth‐ and fifth‐order spherical harmonic shimming for all measured field maps, respectively. Coil elements show novel coil layouts compared to the conventional spherical harmonic coils and existing multi‐coils. Both leave‐one‐out and independent validation demonstrate the generalization ability of the designed arrays. The bootstrapping analysis predicts that field maps from approximately 140 subjects need to be acquired to arrive at a stable design.
Conclusions
The results demonstrate the validity of the proposed method to design a shim coil array matched to the human brain anatomy, which naturally satisfies the laws of electrodynamics. The design method may also be applied to develop new shim coil arrays matched to other human organs.
Summary
Autophagy is a conserved degradation system in eukaryotic cells that includes non‐selective and selective processes. Selective autophagy functions as a selective degradation mechanism for ...specific substrates in which autophagy‐related protein 11 (ATG11) acts as an essential scaffold protein. In B. bassiana, there is a unique ATG11 family protein, which is designated as BbATG11. Disruption of BbATG11 resulted in significantly reduced conidial germination under starvation stress. The mutant ΔBbATG11 displayed enhanced sensitivity to oxidative stress and impaired asexual reproduction. The conidial yield was reduced by approximately 75%, and this defective phenotype could be repressed by increasing exogenous nutrients. The virulence of the ΔBbATG11 mutant strain was significantly impaired as indicated in topical and intra‐hemocoel injection bioassays, with a greater reduction in topical infection. Notably, BbATG11 was involved in pexophagy and mitophagy, but these two autophagic processes appeared in different fungal physiological aspects. Both pexophagy and mitophagy were associated with nutrient shift, starvation stress and growth in the host hemocoel, but only pexophagy appeared in both oxidation‐stressed cells and aerial mycelia. This study highlights that BbATG11 mediates pexophagy and mitophagy in B. bassiana and links selective autophagy to the fungal stress response, conidiation and virulence.
To systematically analyze mitogen‐activated protein (MAP) kinase gene families and their expression profiles in sugarcane (Saccharum spp. hybrids; Sh) under diverse biotic and abiotic stresses, we ...identified 15 ShMAPKs, 6 ShMAPKKs and 16 ShMAPKKKs genes in the sugarcane cultivar R570 genome. These were also confirmed in one S. spontaneum genome and two transcriptome datasets of sugarcane trigged by Acidovorax avenae subsp. avenae (Aaa) and Xanthomonas albilineans (Xa) infections. Phylogenetic analysis revealed that four subgroups were present in each ShMAPK and ShMAPKK family and three sub‐families (RAF, MEKK and ZIK) presented in the ShMAPKKK family. Conserved protein motif and gene structure analyses supported the evolutionary relationships of the three families inferred from the phylogenetic analysis. All of the ShMAPK, ShMAPKK and ShMAPKKK genes identified in Saccharum spp. R570 were distributed on chromosomes 1–7 and 9–10. RNA‐seq and qRT‐PCR analyses indicated that ShMAPK07 and ShMAPKKK02 were defense‐responsive genes in sugarcane challenged by both Aaa and Xa stimuli, while some genes were upregulated specifically by Aaa and Xa infection. Additionally, ShMAPK05 acted as a negative regulator under drought and salinity stress, but served as a positive regulator under salicylic acid (SA) treatment. ShMAPK07 plays a positive role under drought stress, but a negative role under SA treatment. ShMAPKKK01 was negatively modulated by both salinity stress and SA treatment, whereas ShMAPKKK06 was positively regulated by both of the two stress stimuli. Our results suggest that members of MAPK cascade gene families regulate adverse stress responses through multiple signal transduction pathways in sugarcane.
Electroencephalography (EEG) concurrently collected with functional magnetic resonance imaging (fMRI) is heavily distorted by the repetitive gradient coil switching during the fMRI acquisition. The ...performance of the typical template-based gradient artifact suppression method can be suboptimal because the artifact changes over time. Gradient artifact residuals also impede the subsequent suppression of ballistocardiography artifacts.
Here we propose recording continuous EEG with temporally sparse fast fMRI (fast fMRI-EEG) to minimize the EEG artifacts caused by MRI gradient coil switching without significantly compromising the field-of-view and spatiotemporal resolution of fMRI. Using simultaneous multi-slice inverse imaging to achieve whole-brain fMRI with isotropic 5-mm resolution in 0.1 s, and performing these acquisitions once every 2 s, we have 95% of the duty cycle available to record EEG with substantially less gradient artifact. We found that the standard deviation of EEG signals over the entire acquisition period in fast fMRI-EEG was reduced to 54% of that in conventional concurrent echo-planar imaging (EPI) and EEG recordings (EPI-EEG) across participants. When measuring 15-Hz steady-state visual evoked potentials (SSVEPs), the baseline-normalized oscillatory neural response in fast fMRI-EEG was 2.5-fold of that in EPI-EEG. The functional MRI responses associated with the SSVEP delineated by EPI and fast fMRI were similar in the spatial distribution, the elicited waveform, and detection power. Sparsely interleaved fast fMRI-EEG provides high-quality EEG without substantially compromising the quality of fMRI in evoked response measurements, and has the potential utility for applications where the onset of the target stimulus cannot be precisely determined, such as epilepsy.
•We propose recording continuous EEG with temporally sparse fast fMRI.•Fast MRI can achieve whole-brain sampling with isotropic 5-mm resolution in 0.1 s.•Using fast MRI once every 2 s substantially reduces the EEG gradient artifact.•The 15-Hz SSVEP in fast fMRI-EEG was 2.5-fold of that in EPI-EEG.•The fMRI responses for 15-Hz SSVEP were similar in EPI and fast fMRI.
Display omitted
•The mechanism of chemodynamic therapy (CDT) is discussed.•Strategies to augment Fenton for enhanced CDT (ECDT) are systematically summarized.•Various external energy fields as ...auxiliary modalities for ECDT are introduced.•Current challenges and prospective development of ECDT are discussed.
The past few years have witnessed the rise of chemodynamic therapy (CDT) as an emerging strategy for malignant tumors suppression. Nanoplatform-based CDT has great potential due to its highly effective, non-invasive and independent on external energy input. Nevertheless, it is still far from practical use in clinic due to its suboptimal efficacy. Considering that chemodynamic agents promote hydroxyl free radicals (OH) generation through Fenton/Fenton-like reaction in response to tumor microenvironment (TME) is the core of CDT, significant efforts have been devoted to studying enhanced CDT (ECDT) by manipulating intratumoral Fenton chemistry. In this review, the strategies to improve nanoplatform-based CDT efficacy are categorized and systematically introduced. As highlighted, these strategies can also be integrated into CDT-related combination therapy for therapeutic efficiency enhancement. Therefore, from basic principles, CDT-related synergistic therapies with the introduction of various external energy fields as auxiliary modalities are also discussed. Besides, current challenges and prospective developments of ECDT are reviewed. This review is expected to provide inspiration for further improving CDT efficiency to achieve more precise and efficient cancer therapy, and also promote more in-depth researches on nanoplatform-based chemodynamic cancer therapy to facilitate clinical translation.
PDF
