Brain SPECT as a Biomarker of Neurodegeneration in Dementia in the Era of Molecular Imaging: Still a Valid Option?

Ferrando, R; Damián, Araceli

doi:10.3389/fneur.2021.629442

Cited by 32 publications

(30 citation statements)

References 99 publications

(146 reference statements)

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“…After administering SPECT probes, scintillation camera systems are used to trace the probes via gamma rays that are emitted from decaying probes accumulated in hypoxic areas. Although ionizing gamma radiation is used, SPECT is a promising imaging method in terms of high sensitivity and practically limitless depth penetration that makes it a vital molecular imaging modality in preclinical and clinical imaging of not only tumors but also neurodegenerative diseases and cardiac function [ 156 , 157 , 158 , 159 ].…”

Section: Types Of Imaging Modalitiesmentioning

confidence: 99%

Dual-Mode Tumor Imaging Using Probes That Are Responsive to Hypoxia-Induced Pathological Conditions

et al. 2022

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Hypoxia in solid tumors is associated with poor prognosis, increased aggressiveness, and strong resistance to therapeutics, making accurate monitoring of hypoxia important. Several imaging modalities have been used to study hypoxia, but each modality has inherent limitations. The use of a second modality can compensate for the limitations and validate the results of any single imaging modality. In this review, we describe dual-mode imaging systems for the detection of hypoxia that have been reported since the start of the 21st century. First, we provide a brief overview of the hallmarks of hypoxia used for imaging and the imaging modalities used to detect hypoxia, including optical imaging, ultrasound imaging, photoacoustic imaging, single-photon emission tomography, X-ray computed tomography, positron emission tomography, Cerenkov radiation energy transfer imaging, magnetic resonance imaging, electron paramagnetic resonance imaging, magnetic particle imaging, and surface-enhanced Raman spectroscopy, and mass spectrometric imaging. These overviews are followed by examples of hypoxia-relevant imaging using a mixture of probes for complementary single-mode imaging techniques. Then, we describe dual-mode molecular switches that are responsive in multiple imaging modalities to at least one hypoxia-induced pathological change. Finally, we offer future perspectives toward dual-mode imaging of hypoxia and hypoxia-induced pathophysiological changes in tumor microenvironments.

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Section: Types Of Imaging Modalitiesmentioning

confidence: 99%

Dual-Mode Tumor Imaging Using Probes That Are Responsive to Hypoxia-Induced Pathological Conditions

et al. 2022

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“…These modalities use exogenous contrast agents [ 12 ]. SPECT and FDG PET have been widely used in the diagnosis of MCI and AD for over 3 decades [ 13 ]. SPECT showed a specificity of 80% and a sensitivity of 90% in distinguishing AD patients from cognitively normal controls.…”

Section: Introductionmentioning

confidence: 99%

“…This reduction is believed to be greater than the cost of annual testing with these modalities. Reference [ 13 ] presents DSC-MRI, a relatively novel technique in current clinical practice. This technique utilizes gadolinium-based agents to measure CBF, cerebrovascular volume (CBV), and mean transit time [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

The Utility of Arterial Spin Labeling MRI in Medial Temporal Lobe as a Vascular Biomarker in Alzheimer’s Disease Spectrum: A Systematic Review and Meta-Analysis

et al. 2022

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We sought to systematically review and meta-analy the role of cerebral blood flow (CBF) in the medial temporal lobe (MTL) using arterial spin labeling magnetic resonance imaging (ASL-MRI) and compare this in patients with Alzheimer’s disease (AD), individuals with mild cognitive impairment (MCI), and cognitively normal adults (CN). The prevalence of AD is increasing and leading to high healthcare costs. A potential biomarker that can identify people at risk of developing AD, whilst cognition is normal or only mildly affected, will enable risk-stratification and potential therapeutic interventions in the future. All studies investigated the role of CBF in the MTL and compared this among AD, MCI, and CN participants. A total of 26 studies were included in the systematic review and 11 in the meta-analysis. Three separate meta-analyses were conducted. Four studies compared CBF in the hippocampus of AD compared with the CN group and showed that AD participants had 2.8 mL/min/100 g lower perfusion compared with the CN group. Eight studies compared perfusion in the hippocampus of MCI vs. CN group, which showed no difference. Three studies compared perfusion in the MTL of MCI vs. CN participants and showed no statistically significant differences. CBF measured via ASL-MRI showed impairment in AD compared with the CN group in subregions of the MTL. CBF difference was significant in hippocampus between the AD and CN groups. However, MCI and CN group showed no significant difference in subregions of MTL

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“…Although not used for imaging AD, [ 123 I]FP-CIT (Datscan) is used frequently to image dopaminergic tone in Parkinson's disease (32). As 123 I is not readily available in low-and middle-income countries (33), an alternative tropane for dopamine transporters, [ 99m Tc]Trodat, represents the only clinically approved, targeted 99m Tc-based radiotracer (34)(35)(36). The success of [ 99m Tc]Trodat holds promise that a 99m Tc-based amyloid radiotracer is achievable.…”

Section: Introductionmentioning

confidence: 99%

Historical efforts to develop 99mTc-based amyloid plaque targeting radiotracers

2022

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Imaging biomarkers have changed the way we study Alzheimer's disease and related dementias, develop new therapeutics to treat the disease, and stratify patient populations in clinical trials. With respect to protein aggregates comprised of amyloid-β plaques and tau neurofibrillary tangles, Positron Emission Tomography (PET) has become the gold standard imaging modality for quantitative visualization. Due to high infrastructural costs, the availability of PET remains limited to large urban areas within high income nations. This limits access to leading edge medical imaging, and potentially access to new treatments, by millions of rural and remote residents in those regions as well as billions of people in middle- and low-income countries. Single Photon Emission Computed Tomography (SPECT) is a more widely available imaging alternative with lower infrastructural costs and decades of familiarity amongst nuclear medicine professionals. Recent technological advances have closed the gap in spatial resolution and quantitation between SPECT and PET. If effective SPECT radiotracers were available to visualize amyloid-β plaques, geographic barriers to imaging could be circumvented. In this review, we will discuss past efforts to develop SPECT radiotracers targeting amyloid-β plaques which incorporate the most used radionuclide in nuclear medicine: technetium-99m (99mTc; t1/2 = 6.01 h; γ = 140 keV). While reviewing the various chemical scaffolds and chelates employed, the focus will be upon the impact to the pharmacological properties of putative 99mTc-based amyloid-targeting radiotracers.

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Brain SPECT as a Biomarker of Neurodegeneration in Dementia in the Era of Molecular Imaging: Still a Valid Option?

Cited by 32 publications

References 99 publications

Dual-Mode Tumor Imaging Using Probes That Are Responsive to Hypoxia-Induced Pathological Conditions

Dual-Mode Tumor Imaging Using Probes That Are Responsive to Hypoxia-Induced Pathological Conditions

The Utility of Arterial Spin Labeling MRI in Medial Temporal Lobe as a Vascular Biomarker in Alzheimer’s Disease Spectrum: A Systematic Review and Meta-Analysis

Historical efforts to develop 99mTc-based amyloid plaque targeting radiotracers

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