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Thư viện số Văn Lang: Perspectives on Nuclear Medicine for Molecular Diagnosis and Integrated Therapy

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Nguyễn Gia Hào

Academic year: 2023

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Brain regions containing target binding sites (target tissue) have at least three compartments (or two-tissue (2T) compartments) (Fig.17.1a. top). The tissue ratio minus 1 at equilibrium can also be estimated using the traditional compartment model (Fig.17.1a) using the parent-only input function (CPa(t)) if data fitting can be adequately achieved.

Fig. 17.2 Time activity curves (TACs) in the brain (a) and arterial plasma (b) after the injection of
Fig. 17.2 Time activity curves (TACs) in the brain (a) and arterial plasma (b) after the injection of

Conclusions

The data suggest that FMISO PET may be a useful tool for differentiating glioblastomas from lower-grade gliomas. Finally, we evaluated the diagnostic performance of FMISO PET for gliomas and suggest that FMISO PET could help in the diagnosis of glioblastomas when PET images are acquired 4 hours after injection.

Introduction

We hypothesized that hypoxia imaging of glioblastomas might be useful in distinguishing glioblastomas from lower-grade gliomas. If such a difference could be proven, hypoxia imaging using FMISO would provide a way to distinguish glioblastomas from lower-grade gliomas.

Materials and Methods

Where the maximum uptake in the tumor was weaker than that in the surrounding brain tissue, the patient was considered to show low FMISO uptake. Where peak uptake in the tumor was stronger than that in the surrounding brain tissue, the patient was considered to exhibit high FMISO uptake.

Results

Finally, the uptake volume of FMISO was greater in glioblastoma than in non-glioblastoma patients. In the second study, the 2-hour images and the 4-hour images of FMISO PET were directly compared for the same subjects. Visually, the SUV in the brain was higher after 2 hours than after 4 hours. More specifically, the gray matter SUV was higher at 2 hours than at 4 hours, while the white matter SUV was comparable in the 2 hour and 4 hour images. a) The FLAIR image showed a tumor in the left frontal lobe.

Here, lower grade gliomas (grade II and III) showed decreases in SUVmax and in the ratio of tumor to normal from 2 hours to 4 hours (Fig. 18.10).

Fig. 18.1 A glioblastoma case. (a) The FLAIR image showed a high-signal tumor in the left hemisphere
Fig. 18.1 A glioblastoma case. (a) The FLAIR image showed a high-signal tumor in the left hemisphere

Discussion

In the first study, the FMISO PET images were variously evaluated by visual assessment, SUV, lesion-to-normal tissue ratio, and recording volume. Both SUVmax and SUV10mm with FMISO were higher in glioblastoma patients than in non-glioblastoma patients; the range of values ​​for the groups overlaps, possibly explained by interindividual variability in the SUV. In the study here, left and right cerebral cortex FMISO accumulation showed no significant asymmetry (data not shown); however, it can be assumed that this is not a problem when using the lesion-to-cerebellum ratio.

To further confirm the findings, the volume of FMISO uptake in the tumor was measured and compared for patients with glioblastoma and patients without glioblastoma.

Fig. 18.11 A scheme of the suggested roles of 11  C-methionine (MET), 18  F-FDG, and 18 F-FMISO PET in differential diagnosis of gliomas
Fig. 18.11 A scheme of the suggested roles of 11 C-methionine (MET), 18 F-FDG, and 18 F-FMISO PET in differential diagnosis of gliomas

Conclusions

Optimization of semi-quantitation in metabolic PET studies with 18F-fluorodeoxyglucose and 11C-methionine in determining glioma malignancy. Complementary but distinct roles for MRI and 18F-fluoromisonidazole PET in the assessment of human glioblastomas. Assessment of regional tumor hypoxia using 18F-fluoromisonidazole and 64Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone) positron emission tomography: comparative study with microPET imaging, Po2 probe measurement, autoradiography, and fluorescence microscopy in the R3327-AT and FaDu rat tumor models.

Combining these imaging biomarkers with classical CBF measurement may contribute to the development of innovative drugs for pharmacological neuroprotection in cerebral infarction therapy.

Introduction

Abstract Since cerebral infarction results from a reduction in cerebral blood flow (CBF) from occlusion or stenosis of the carotid or intracranial arteries, CBF is a primary parameter to predict ischemic brain injury. Single-photon emission tomography (SPECT) and positron emission tomography (PET) contributed to the evaluation of the loss of cerebral autoregulation, the state of uncoupling between CBF and brain metabolism, and the ischemic hemiplegia. Measurement of CBF and oxygen metabolism by 15O PET revealed the process of infarct growth in the hyperacute phase of cerebral infarction and areas with depressed oxygen metabolism, but normal water diffusion on magnetic resonance imaging (MRI) was called the "metabolic penumbra ". Recently, several researchers shed light on the role of glial cells in brain energy metabolism and 11C-acetate PET and demonstrated that astrocytic energy metabolism in the TCA cycle was protective against ischemia.

In this chapter, we introduce the use of PET and SPECT imaging in studies to explain the process of cerebral infarction.

Fig. 19.1 Time course of infarct evolution and related PET/SPECT imaging
Fig. 19.1 Time course of infarct evolution and related PET/SPECT imaging

Perfusion and Oxygen Metabolism in Brain Ischemia

Such increases in OEF are known as “misery perfusion” and can be observed during the acute stage of cerebral infarction (Fig. 19.3). In the chronic stage of cerebral infarction, misery perfusion in patients with unilateral carotid artery occlusion suggests a high likelihood of stroke recurrence [6–8].

Infarct Growth in Acute Cerebral Infarction

When the CBF was less than 20% of that in the unaffected hemisphere, the risk of a hemorrhagic infarction after recanalization therapy increased [14]. A diffusion-weighted MR image obtained 1.3 hours after onset (a) showed only a small lesion in the frontal lobe. 99mHMPAO-SPECT image obtained 2.3 hours after onset (b) showed a broad reduction of CBF in the left hemisphere.

ATP-dependent neuronal membrane ion pump in the developing infarct region as early as 6 h after onset.

Fig. 19.4 Prediction of cerebral infarction by acute CBF-SPECT. A diffusion-weighted MR image obtained at 1.3 h after onset (a) demonstrated only a small lesion in the frontal lobe
Fig. 19.4 Prediction of cerebral infarction by acute CBF-SPECT. A diffusion-weighted MR image obtained at 1.3 h after onset (a) demonstrated only a small lesion in the frontal lobe

Role of Astrocytic Function in Brain Ischemia

This glucose is processed glycolytically, resulting in the release of lactate as an energy substrate for neurons. In the ischemic brain where ATP synthesis is limited, the conversion of glutamate into the synaptic cleft is disturbed. Therefore, the glutamate-glutamine cycle and ANLS are deeply linked to astrocytic function and play a critical role in the evolution from stroke to infarction.

For the specific imaging of astrocytes, acetate is expected to be useful as a selective marker of astrocytic energy metabolism [18,19]. 14C-acetate is rapidly incorporated into glutamine via glutamate by glutamine synthetase localized in astrocytic cells [20].

Fig. 19.6 Qualitative and quantitative 11 C-acetate PET imaging for astrocytic energy metabolism.
Fig. 19.6 Qualitative and quantitative 11 C-acetate PET imaging for astrocytic energy metabolism.

Selective Neuronal Loss in Ischemic Brain Injury

Detection of Tissue Hypoxia

They demonstrated that 18F-FMISO uptake in the ischemic brain was elevated only during the early phase of middle cerebral artery (MCA) occlusion. They also showed that tissue without 18F-FMISO uptake within the final infarct was assumed to be infarcted at the time of the acute 18F-FMISO PET. These experimental and clinical results are very interesting because they suggested that 18F-FMISO uptake changes continuously during cerebral infarction.

Since 18F-FMISO PET cannot distinguish between the entire infarct area and non-hypoxically viable tissue during the acute phase of the infarction, the timing of the PET examination is likely to be critical in diagnosing whether the tissue is salvageable.

Imaging of Neuroinflammation

Within 6 hours of onset, a higher hypoxic volume was observed in the core of the infarct, and the location moved to the periphery or outside the infarct at later time points.

Summary

Grubb Jr RL, Derdeyn CP, Fritsch SM, Carpenter DA, Yundt KD, Videen TO, et al. Imaging brain hypoxia in permanent and temporary occlusion of the middle cerebral artery in the rat using 18F-fluoromisonidazole and positron emission tomography: a pilot study. In this situation, it is important to maintain our cognitive function throughout life by preventing pathological brain aging from occurring.

In addition, having intellectual curiosity showed a significant negative correlation with the regional rate of gray matter volume decline in the temporoparietal region.

Introduction

Imaging Studies of Brain Development

Correlation Between Gray Matter Density-Adjusted Brain Perfusion and Age Using Brain MR Images

As a result, the correlation between BP-GMD and age showed an inverted U-shape, followed by a U-shaped trajectory in most regions [1-3]. In the frontal lobe, all gray matter regions showed an inverted U-shaped trajectory for the correlation between BP-GMD and age, and the best fit was a negative quadratic or positive cubic polynomial function. We demonstrated a correlation between BP-GMD and age using ASL brain perfusion MRI in a large number of healthy children over a wide age range.

As a result, the trajectory of the correlation between BP-GMD and age showed an inverted U-shape, followed by a U-shaped trajectory in most regions.

Fig. 20.1 Schematic of the image analysis
Fig. 20.1 Schematic of the image analysis

Correlation Between Sleep Duration and Gray Matter Volume Using Brain MR Images of 290 Healthy

Imaging Studies of Brain Aging

Correlation Between Baseline Regional Gray Matter Volume and Global Gray Matter Volume Decline Rate

Therefore, we used the gray matter regions of the right PCC/precuneus and the left hippocampus in the following discriminant analysis. Baseline regional gray matter volume of both the right PCC/precuneus and the left hippocampus significantly differentiated whether APCGMR was above or below the APCGMR mean. This study provides the first longitudinal findings demonstrating that regional gray matter volumes in the right PCC/precuneus and left hippocampus exhibit a significant negative correlation with the rate of global gray matter volume decline at baseline.

In addition, baseline regional gray matter volumes of both the right PCC/precuneus and the left hippocampus significantly differentiated whether the APCGMR was above or below the APCGMR mean.

Correlation Between Degree of White Matter Hyperintensities and Global Gray Matter Volume

Our results show that baseline regional gray matter volume predicts the rate of global gray matter volume decline over the next period in healthy subjects. Our results suggest that the degree of global gray matter volume reduction could be predicted using the degree of WMH at baseline, evaluated by simple visual scaling. In summary, using a longitudinal design over 6 years in 160 healthy community-dwelling individuals, the degree of WMH was measured at baseline and the degree of global gray matter volume reduction was obtained.

Our results suggest that the degree of WMHs at baseline predicts the rate of subsequent gray matter volume decline and also suggest that simple visual scaling of WMHs may contribute to the prediction of the rate of global gray matter volume decline.

Risk Factors for Brain Volume Decrease

As a result, APCGMR showed a significant positive correlation with the rate of deep WMHs and periventricular WMHs at baseline adjusting for age, sex, and current history of hypertension and diabetes mellitus. Volumetric analysis revealed significant negative correlations between BMI and gray matter ratio, which represents the percentage of gray matter volume in intracranial volume, in men (p<0.001, adjusting for age, systolic blood pressure and alcohol intake throughout life). , while not in women. VBM revealed that regional gray matter volumes of the bilateral medial temporal lobe, occipital lobe, frontal lobe, and anterior cerebellar lobe show a significant negative correlation with BMI, and those of the posterior cerebellar lobe, perisylvian regions of bilateral frontal and temporal lobes and bilateral orbitofrontal gyri show a significant positive correlation with BMI in men [6] (Fig.20.5).

Conclusion

Hình ảnh

Fig. 17.2 Time activity curves (TACs) in the brain (a) and arterial plasma (b) after the injection of
Fig. 17.4 Coronal parametric images of AD and HC. The MRTM O BP * ND images in ADs (a) and HCs (b)
Fig. 18.1 A glioblastoma case. (a) The FLAIR image showed a high-signal tumor in the left hemisphere
Fig. 18.3 An anaplastic oligoastrocytoma case (grade III). (a) The FLAIR image showed a tumor in the right frontal lobe
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