Delayed reduction of tissue water diffusion after myocardial ischemia

1998 ◽  
Vol 275 (2) ◽  
pp. H697-H702 ◽  
Author(s):  
Edward W. Hsu ◽  
Rong Xue ◽  
Alex Holmes ◽  
John R. Forder
Keyword(s):  
Myocardial Infarction ◽  
Myocardial Ischemia ◽  
Morphological Analysis ◽  
Tissue Water ◽  
Apparent Diffusion ◽  
Regional Myocardial Ischemia ◽  
Contrast Mechanism ◽  
Tissue Contrast ◽  
Affected Tissue ◽  
Magnetic Resonance Imaging Mri

The apparent diffusion coefficient (ADC) of water after regional myocardial ischemia was measured in isolated, perfused rabbit hearts by using magnetic resonance imaging (MRI) techniques. After ligation of the left anterior descending coronary artery, the ADC of the nonperfused region showed a gradual but significant decreasing trend over time, whereas that of the normally perfused myocardium remained constant. Morphological analysis revealed that the ADC decrease reflected the expansion of a subregion of reduced ADC within the nonperfused myocardium. The dynamics of the diffusion change and the morphological progression of the affected tissue suggest that the ADC decrease may be linked to the onset of myocardial infarction, which is known to involve myocyte swelling. The ADC reduction provides a potentially valuable MRI tissue-contrast mechanism for noninvasively determining the viability of the ischemic myocardium and assessing the dynamics of acute myocardial infarction.

scholarly journals Endothelial β1 Integrin-Mediated Adaptation to Myocardial Ischemia

2021 ◽  
Author(s):  
Carina Henning ◽  
Anna Branopolski ◽  
Paula Follert ◽  
Oksana Lewandowska ◽  
Aysel Ayhan ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Coronary Artery ◽  
Myocardial Ischemia ◽  
Cardiac Function ◽  
Integrin Subunit ◽  
Β1 Integrin ◽  
Human Coronary Artery ◽  
Tetrazolium Chloride ◽  
Magnetic Resonance Imaging Mri ◽  
Interfering Rna

Abstract Background Short episodes of myocardial ischemia can protect from myocardial infarction. However, the role of endothelial β1 integrin in these cardioprotective ischemic events is largely unknown. Objective In this study we investigated whether endothelial β1 integrin is required for cardiac adaptation to ischemia and protection from myocardial infarction. Methods Here we introduced transient and permanent left anterior descending artery (LAD) occlusions in mice. We inhibited β1 integrin by intravenous injection of function-blocking antibodies and tamoxifen-induced endothelial cell (EC)-specific deletion of Itgb1. Furthermore, human ITGB1 was silenced in primary human coronary artery ECs using small interfering RNA. We analyzed the numbers of proliferating ECs and arterioles by immunohistochemistry, determined infarct size by magnetic resonance imaging (MRI) and triphenyl tetrazolium chloride staining, and analyzed cardiac function by MRI and echocardiography. Results Transient LAD occlusions were found to increase EC proliferation and arteriole formation in the entire myocardium. These effects required β1 integrin on ECs, except for arteriole formation in the ischemic part of the myocardium. Furthermore, this integrin subunit was also relevant for basal and mechanically induced proliferation of human coronary artery ECs. Notably, β1 integrin was needed for cardioprotection induced by transient LAD occlusions, and the absence of endothelial β1 integrin resulted in impaired growth of blood vessels into the infarcted myocardium and reduced cardiac function after permanent LAD occlusion. Conclusion We showed that endothelial β1 integrin is required for adaptation of the heart to cardiac ischemia and protection from myocardial infarction.

scholarly journals Acute Astrocyte Activation in Brain Detected by Mri: New Insights into T1 Hypointensity

2007 ◽  
Vol 28 (3) ◽  
pp. 621-632 ◽  
Author(s):  
Nicola R Sibson ◽  
John P Lowe ◽  
Andrew M Blamire ◽  
Matthew J Martin ◽  
Tiho P Obrenovitch ◽  
...  
Keyword(s):  
Experimental Models ◽  
Low Flow ◽  
Astrocyte Activation ◽  
Tissue Water ◽  
Signal Change ◽  
Apparent Diffusion ◽  
Acute Increase ◽  
Magnetic Resonance Imaging Mri ◽  
The Brain ◽  
Intrastriatal Injection

Increases in the T1 of brain tissue, which give rise to dark or hypointense areas on T1-weighted images using magnetic resonance imaging (MRI), are common to a number of neuropathologies including multiple sclerosis (MS) and ischaemia. However, the biologic significance of T1 increases remains unclear. Using a multiparametric MRI approach and well-defined experimental models, we have experimentally induced increases in tissue T1 to determine the underlying cellular basis of such changes. We have shown that a rapid acute increase in T1 relaxation in the brain occurs in experimental models of both low-flow ischaemia induced by intrastriatal injection of endothelin-1 (ET-1), and excitotoxicity induced by intrastriatal injection of N-methyl-d-aspartate (NMDA). However, there appears to be no consistent correlation between increases in T1 relaxation and changes in other MRI parameters (apparent diffusion coefficient, T2 relaxation, or magnetisation transfer ratio of tissue water). Immunohistochemically, one common morphologic feature shared by the ET-1 and NMDA models is acute astrocyte activation, which was detectable within 2 h of intracerebral ET-1 injection. Pretreatment with an inhibitor of astrocyte activation, arundic acid, significantly reduced the spatial extent of the T1 signal change induced by intrastriatal ET-1 injection. These findings suggest that an increase in T1 relaxation may identify the acute development of reactive astrocytes within a central nervous system lesion. Early changes in T1 may, therefore, provide insight into acute and reversible injury processes in neurologic patients, such as those observed before contrast enhancement in MS.

scholarly journals Clinical and Pathological Evidence of Anti-GD2 Immunotherapy Induced Differentiation in Relapsed/Refractory High-Risk Neuroblastoma

Cancers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1264
Author(s):  
Jaume Mora ◽  
Alicia Castañeda ◽  
Maria Cecilia Colombo ◽  
Maite Gorostegui ◽  
Fernando Gomez ◽  
...  
Keyword(s):  
High Risk ◽  
Fdg Pet ◽  
Current Therapy ◽  
Bone Lesions ◽  
Functional Magnetic Resonance ◽  
Positron Emission ◽  
Apparent Diffusion ◽  
Neuroblastic Tumors ◽  
Direct Cell ◽  
Magnetic Resonance Imaging Mri

Background: Neuroblastic tumors (NBTs) originate from a block in the process of differentiation. Histologically, NBTs are classified in neuroblastoma (NB), ganglioneuroblastoma (GNB), and ganglioneuroma (GN). Current therapy for high-risk (HR) NB includes chemotherapy, surgery, radiotherapy, and anti-GD2 monoclonal antibodies (mAbs). Anti-GD2 mAbs induce immunological cytoxicity but also direct cell death. Methods: We report on patients treated with naxitamab for chemorefractory NB showing lesions with long periods of stable disease. Target lesions with persisting 123I-Metaiodobenzylguanidine (MIBG) uptake after 4 cycles of immunotherapy were further evaluated by functional Magnetic Resonance Imaging (MRI) and/or Fluorodeoxyglucose (FDG)-positron emission tomography (PET). MIBG avid lesions that became non-restrictive on MRI (apparent diffusion coefficient (ADC) > 1) and/or FDG-PET negative (SUV < 2) were biopsied. Results: Twenty-seven relapse/refractory (R/R) HR-NB patients were enrolled on protocol Ymabs 201. Two (7.5%) of the 27 showed persistent bone lesions on MIBG, ADC high, and/or FDG-PET negative. Forty-four R/R HR-NB patients received chemo-immunotherapy. Twelve (27%) of the 44 developed persistent MIBG+ but FDG-PET- and/or high ADC lesions. Twelve (86%) of the 14 cases identified were successfully biopsied producing 16 evaluable samples. Histology showed ganglioneuroma maturing subtype in 6 (37.5%); ganglioneuroma mature subtype with no neuroblastic component in 4 (25%); differentiating NB with no Schwannian stroma in 5 (31%); and undifferentiated NB without Schwannian stroma in one (6%). Overall, 10 (62.5%) of the 16 specimens were histopathologically fully mature NBTs. Conclusions: Our results disclose an undescribed mechanism of action for naxitamab and highlight the limitations of conventional imaging in the evaluation of anti-GD2 immunotherapy clinical efficacy for HR-NB.

The Effects of Intravenous Clonidine on Regional Myocardial Function in a Canine Model of Regional Myocardial Ischemia

1994 ◽  
Vol 78 (6) ◽  
pp. 1047???1052 ◽  
Author(s):  
Masashi Kono ◽  
Shigeho Morita ◽  
Takayuki Hayashi ◽  
Mieko Saitoh ◽  
Nobuo Fuke ◽  
...  
Keyword(s):  
Myocardial Ischemia ◽  
Myocardial Function ◽  
Canine Model ◽  
Regional Myocardial Function ◽  
Regional Myocardial Ischemia

Increased muscle fiber fractional anisotropy value using diffusion tensor imaging after compression without fiber injury

2021 ◽  
pp. 028418512110582
Author(s):  
Takumi Yokohama ◽  
Motoyuki Iwasaki ◽  
Daisuke Oura ◽  
Sho Furuya ◽  
Yoshimasa Niiya
Keyword(s):  
Diffusion Tensor Imaging ◽  
Fractional Anisotropy ◽  
Muscle Tissue ◽  
Diffusion Tensor ◽  
Longitudinal Direction ◽  
Diffusion Parameters ◽  
Apparent Diffusion ◽  
The Mean ◽  
Magnetic Resonance Imaging Mri ◽  
Age Range

Background Recent studies have indicated that injuries such as muscle tears modify the microstructural integrity of muscle, leading to substantial alterations in measured diffusion parameters. Therefore, the fractional anisotropy (FA) value decreases. However, we hypothesized that soft tissue, such as muscle tissue, undergoes reversible changes under conditions of compression without fiber injury. Purpose To evaluate the FA change due to compression in muscle tissue without fiber injury. Material and Methods Diffusion tensor imaging (DTI) was performed on both feet of 10 healthy volunteers (mean age = 35.0 ± 10.39 years; age range = 23–52 years) using a 3.0-T magnetic resonance imaging (MRI) scanner with an eight-channel phased array knee coil. An MRI-compatible sphygmomanometer was applied to the individuals’ lower legs and individuals were placed in a compressed state. Then, rest intervals of 5 min were set in re-rest state after compression. The FA value, apparent diffusion coefficient (ADC), and eigenvalues (λ1, λ2, λ3) of the gastrocnemius and soleus muscle were measured at each state. Results The mean FA values increased in all muscles in a compressed state, while the mean λ3 decreased. In all muscles, significant differences were found between the rest and compressed states in terms of mean FA and λ3 ( P < 0.0001). Conclusion We confirmed the reversibility of the DTI metrics, which suggests that there was no muscle injury during this study. In cases of compression without fiber injury, the FA value increases, because fibers are strongly aligned in the longitudinal direction.

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