Relationship between the temporal course of astrogliosis and symptom improvement in cerebral infarction: report of a case monitored using 18F-THK5351 positron emission tomography

Clinical Application of 18 F-THK5351 PET to Image Ongoing Astrogliosis in MSA-P and MSA-C

ABSTRACT

18 F-labeled THK5351 PET can visualize ongoing astrogliosis by estimating monoamine oxidase B levels and can be used as an adjunct for diagnosing neurodegenerative disorders. Little has been reported on multiple system atrophy (MSA) in the differential diagnosis of parkinsonian syndromes. Here, we present 18 F-THK5351 images in typical cases of MSA-P (parkinsonian type) and MSA-C (cerebellar type), showing intense 18 F-THK5351 uptake in the lateral-posterior part of the putamen (MSA-P) and in the pons and middle cerebellar peduncles (MSA-C). Hence, this study illustrates the possible utility of 18 F-THK5351 PET as an adjunct for diagnosing MSA-P and MSA-C by imaging ongoing astrogliosis.

18F-THK5351 Uptake May Not Estimate Neurofibrillary Tangles in In Vivo Images: A Comparison With 18F-MK-6240 Uptake

ABSTRACT

Currently, monoamine oxidase B is recognized as the primary target of 18F-THK5351, although 18F-THK5351 was initially developed to target neurofibrillary tangles (NFTs) in Alzheimer disease. When clinically applying 18F-THK5351 PET to visualize ongoing astrogliosis via estimating monoamine oxidase B levels, a crucial concern is how much degree 18F-THK5351 uptake reflects NFTs in in vivo images. To unravel this concern, a head-to-head comparison between 18F-THK5351 and 18F-MK-6240 (estimating NFT) images in the NFT lesion ideally without accompanying astrogliosis is essential. Here, we present such a case suggesting that 18F-THK5351 uptake may not estimate NFTs in in vivo images.

Predictive value of Cmmi-MHR combined with thromboelastography parameters in acute cerebral infarction

Cerebral infarction is a common neurological disease with high rates of morbidity, mortality, and recurrence, posing a great threat to human life and health. Cerebral infarction is the second leading cause of death in the world and the leading cause of long-term disability in humans. The results of the third national retrospective sampling survey on causes of death in 2008 showed that cerebral infarction has become the leading cause of death in China and its mortality rate is 4-5 times that of European and American countries. Therefore, this article proposed a study on the predictive value of Cmmi-MHR combined with thromboelastography parameters that was performed for acute cerebral infarction. This paper mainly proposed a high frame rate imaging technology and analyzed its algorithm. In this article, in the experimental part, an in-depth analysis of the predictive value of the Monocyte-to-high-density lipoprotein cholesterol ratio (MHR) combined with thromboelastography parameters was performed for acute cerebral infarction. The final experimental results showed that HDL (OR = 1.695%, P-trend = 0.049) had a probability of death within 90 days of hospitalization (OR = 0.81, 95% CI = 1.06-3.11, P-trend = 0.523). There were no significant differences in mortality rate after 90 days. Regardless of adjusting for confounders such as age, gender, and NIHSS score, there was no significant difference in the risk of MHR or monocyte count within 90 days of hospitalization. The conclusion indicates that the combination of Cmmi-MHR and thromboelastography parameters provides a new perspective and method for the diagnosis and treatment of cerebral infarction, and provides important support for personalized treatment and management of cerebral infarction.

Clinical application of MAO-B PET using 18F-THK5351 in neurological disorders

Monoamine oxidase B (MAO-B) is an enzyme localized to the outer mitochondrial membrane and highly concentrated in astrocytes. Temporal changes in regional MAO-B levels can be used as an index of astrocytic proliferation, known as activated astrocytes or astrogliosis. MAO-B is a marker to evaluate the degree of astrogliosis. Therefore, MAO-B positron emission tomography (PET) is a powerful imaging technique for visualizing and quantifying ongoing astrogliosis through the estimate of regional MAO-B levels. Each neurodegenerative disorder generally has a characteristic distribution pattern of astrogliosis secondary to neuronal loss and pathological protein aggregation. Therefore, by imaging astrogliosis, MAO-B PET can be used as a neurodegeneration marker for identifying degenerative lesions. Any inflammation in the brain usually accompanies astrogliosis starting from an acute phase to a chronic phase. Therefore, by imaging astrogliosis, MAO-B PET can be used as a neuroinflammation marker for identifying inflammatory lesions. MAO-B levels are high in gliomas originating from astrocytes but low in lymphoid tumors. Therefore, MAO-B PET can be used as a brain tumor marker for identifying astrocytic gliomas by imaging MAO-B levels and distinguishing between astrocytic and lymphoid tumors. This review summarizes the clinical application of MAO-B PET using 18F-THK5351 as markers for neurodegeneration, neuroinflammation, and brain tumors in neurological disorders. Because we assume that MAO-B PET is clinically applied to an individual patient, we focus on visual inspection of MAO-B images at the individual patient level. Geriatr Gerontol Int 2024; 24: 31-43.

Detailed Assessment of 18F-THK5351 Distribution Pattern in the Midbrain: Comparison With Progressive Supranuclear Palsy and Corticobasal Syndrome

BACKGROUND

18F-THK5351 PET is used to image ongoing astrogliosis by estimating monoamine oxidase B levels. 18F-THK5351 preferentially accumulates around the substantia nigra (SN) and periaqueductal gray (PG) in the midbrain under healthy conditions and exhibits a "trimodal pattern." In progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS), the midbrain 18F-THK5351 uptake can be increased by astrogliosis, collapsing the "trimodal pattern." We aimed to elucidate cases in which the "trimodal pattern" collapses in PSP and CBS.

PATIENTS AND METHODS

Participants in the PSP (n = 11), CBS (n = 17), Alzheimer disease (n = 11), and healthy control (n = 8) groups underwent 18F-THK5351 PET. Volumes of interest (VOIs) were placed on the SN, PG, and their midpoints. The midbrain uptake ratio (MUR) was calculated to assess the trimodal pattern as follows: MUR = (VOI value on the midpoint)/(VOI value on the SN and PG). Approximately, the trimodal pattern can be identified at MUR <1 but not at MUR >1.

RESULTS

Compared with the healthy control group, MUR significantly increased in the PSP (P < 0.01) and CBS (P < 0.01) groups, but was unchanged in the Alzheimer disease group (P = 0.10). In the PSP group, all patients, including 2 with mild symptoms and a short disease duration, showed MUR >1. In the CBS group, MUR varied widely.

CONCLUSIONS

In PSP, the trimodal pattern can collapse even in the early phase when symptoms are mild. In CBS, the trimodal pattern may or may not collapse depending on the underlying pathology.

Clinical Application of 18F-THK5351 PET to Identify Inflammatory Lesions Through Imaging Astrogliosis in a Case of Cytomegalovirus Ventriculoencephalitis

ABSTRACT

18F-THK5351 PET is used to estimate the degree of astrogliosis. Because inflammatory lesions usually accompany astrogliosis, 18F-THK5351 PET is potentially worthy of clinical application in inflammatory disorders. Here, we report a case of cytomegalovirus ventriculoencephalitis in an immunocompromised 75-year-old woman who underwent 18F-THK5351 PET and conventional neuroimaging modalities, including 11C-methionine, 18F-FDG, and MRI. 18F-THK5351 PET was clearly superior to the other modalities in identifying inflammatory lesions and can therefore be a useful marker for identifying inflammatory lesions through imaging astrogliosis. This feature of 18F-THK5351 may contribute to the early diagnosis of cytomegalovirus ventriculoencephalitis.

High sensitivity of asymmetric 18F-THK5351 PET abnormality in patients with corticobasal syndrome

Corticobasal syndrome (CBS) is characterized by symptoms related to the asymmetric involvement of the cerebral cortex and basal ganglia. However, early detection of asymmetric imaging abnormalities can be challenging. Previous studies reported asymmetric ¹⁸F-THK5351 PET abnormalities in CBS patients, but the sensitivity for detecting such abnormalities in larger patient samples, including early-stage cases, remains unclear. Patients clinically diagnosed with CBS were recruited. All patients displayed asymmetric symptoms in the cerebral cortex and basal ganglia. Asymmetric THK5351 PET abnormalities were determined through visual assessment. Brain MRI, perfusion SPECT, and dopamine transporter (DAT) SPECT results were retrospectively reviewed. The 15 patients had a median age of 72 years (59-86 years) and a disease duration of 2 years (0.5-7 years). Four patients met the probable and 11 met the possible CBS criteria according to Armstrong criteria at the time of PET examination. All patients, including early-stage cases, exhibited asymmetric tracer uptake contralateral to their symptom-dominant side in the cerebral cortex/subcortical white matter and striatum (100%). The sensitivity for detecting asymmetric imaging abnormalities contralateral to the symptom-dominant side was 86.7% for brain MRI, 81.8% for perfusion SPECT, and 90% for DAT SPECT. White matter volume reduction was observed in the subcortical region of the precentral gyrus with increased THK5351 uptake, occurring significantly more frequently than gray matter volume reduction. THK5351 PET may be a sensitive imaging technique for detecting asymmetric CBS pathologies, including those in early stages.

Distribution Pattern of the Monoamine Oxidase B Ligand, 18F-THK5351, in the Healthy Brain

BACKGROUND

18F-THK5351 PET estimates the concentrations of monoamine oxidase B (MAO-B) that are preferentially located in astrocytes and can be used to visualize and quantify ongoing astrogliosis. To study images of astrogliosis in neurological disorders, it is essential to understand the detailed binding sites of 18F-THK5351 as the MAO-B ligand under normal conditions. In this study, we examined the detailed distribution pattern of 18F-THK5351 in the healthy brain by comparing 18F-THK5351 uptake between subjects taking and not taking the MAO-B inhibitor.

METHODS

Ten healthy controls (HCs: 67.4 [SD, 15.1] years) and 4 patients with Parkinson disease taking the MAO-B inhibitor underwent 18F-THK5351 PET. The uptake ratio index (URI) was defined to quantify 18F-THK5351 uptake, using the cerebellum as a reference region. The cerebellar URI was set to zero.

RESULTS

For HCs, regions with URI ≥1 were preferentially observed in the following order: the striatum, globus pallidus, thalamus, hypothalamus, amygdala, periaqueductal gray, substantia nigra, medulla, hippocampus, and pons. The peak URI values in the corresponding regions were 2.93, 2.47, 2.12, 2.04, 1.84, 1.68, 1.67, 1.37, 1.20, and 1.11, respectively. For all patients with Parkinson disease taking the MAO-B inhibitor, the URI values in all these regions were significantly decreased (Z score >2) and were reduced from 60.4% to 99.9%, compared with HCs.

CONCLUSIONS

This study presented the detailed distribution pattern of 18F-THK5351 in HCs and suggests that 18F-THK5351 uptake largely reflects MAO-B concentrations under normal conditions.

Temporal and spatial changes in reactive astrogliosis examined by 18F-THK5351 positron emission tomography in a patient with severe traumatic brain injury

Background

The positron emission tomography (PET) radioligand ¹⁸F-THK5351 is now used to evaluate monoamine oxidase B expression in the reactive astrogliosis seen in various central nervous diseases. Traumatic brain injury (TBI) is known to induce reactive astrogliosis in the lesion site. This is a first report to examine the spatial and temporal changes in reactive astrogliosis as evaluated by ¹⁸F-THK5351 after a severe TBI.

Case presentation

A 27-year-old man suffering from a severe TBI with multiple brain contusions was examined using ¹⁸F-THK5351 PET/CT in the subacute and chronic phases after the injury. The first PET scan, performed 46 days after the TBI, showed intense uptake of ¹⁸F-THK5351 in and around the brain contusions. The second PET scan, performed 271 days after the TBI, showed reduced uptake of ¹⁸F-THK5351 at the original sites of the brain contusions and increased uptakes in the white matter surrounding the contusions and the corpus callosum. The patient exhibited sustained improvement of neuropsychological impairment between the two PET examinations and remarkable recovery from the severe TBI.

Conclusions

There were evident temporal and spatial changes in ¹⁸F-THK5351 uptake in the traumatized brain between the two PET examinations. These changes may have been related to the remarkable neurological recovery in this patient. The degree and distribution of reactive astrogliosis detected by ¹⁸F-THK5351 PET may be useful in assessing pathophysiology and predicting prognosis in TBI patients.

18F-THK5351 PET Can Identify Core Lesions in Different Amyotrophic Lateral Sclerosis Phenotypes

ABSTRACT

Two patients with different amyotrophic lateral sclerosis (ALS) phenotypes underwent 18F-THK5351 PET to visualize lesions undergoing astrogliosis by measuring monoamine oxidase B activity. Patient 1 was a 57-year-old man with flail leg syndrome. Elevated uptake was observed inside the motor cortex, corresponding to the leg area in a cortical homunculus. Patient 2 was a 64-year-old man with ALS-frontotemporal dementia semantic variant. Elevated uptake was observed around the left anterior temporal lobe. Both core lesions were consistent with their respective neurological features. Hence, 18F-THK5351 PET is a useful technique to assess ALS pathophysiology by visualizing the core lesions.

Recurrent Lobar Hemorrhages and Multiple Cortical Superficial Siderosis in a Patient of Alzheimer's Disease With Homozygous APOE ε2 Allele Presenting Hypobetalipoproteinemia and Pathological Findings of 18F-THK5351 Positron Emission Tomography: A Case Report

In Alzheimer's disease, the apolipoprotein E gene (APOE) ε2 allele is a protective genetic factor, whereas the APOE ε4 allele is a genetic risk factor. However, both the APOE ε2 and the APOE ε4 alleles are genetic risk factors for lobar intracerebral hemorrhage. The reasons for the high prevalence of lobar intracerebral hemorrhage and the low prevalence of Alzheimer's disease with the APOE ε2 allele remains unknown. Here, we describe the case of a 79-year-old Japanese female with Alzheimer's disease, homozygous for the APOE ε2 allele. This patient presented with recurrent lobar hemorrhages and multiple cortical superficial siderosis. The findings on the ¹¹C-labeled Pittsburgh Compound B-positron emission tomography (PET) were characteristic of Alzheimer's disease. ¹⁸F-THK5351 PET revealed that the accumulation of ¹⁸F-THK 5351 in the right pyramidal tract at the pontine level, the cerebral peduncle of the midbrain, and the internal capsule, reflecting the lesions of the previous lobar intracerebral hemorrhage in the right frontal lobe. Moreover, ¹⁸F-THK5351 accumulated in the bilateral globus pallidum, amygdala, caudate nuclei, and the substantia nigra of the midbrain, which were probably off-target reaction, by binding to monoamine oxidase B (MAO-B). ¹⁸F-THK5351 were also detected in the periphery of prior lobar hemorrhages and a cortical subarachnoid hemorrhage, as well as in some, but not all, areas affected by cortical siderosis. Besides, ¹⁸F-THK5351 retentions were observed in the bilateral medial temporal cortices and several cortical areas without cerebral amyloid angiopathy or prior hemorrhages, possibly where tau might accumulate. This is the first report of a patient with Alzheimer's disease, carrying homozygous APOE ε2 allele and presenting with recurrent lobar hemorrhages, multiple cortical superficial siderosis, and immunohistochemically vascular amyloid β. The ¹⁸F-THK5351 PET findings suggested MAO-B concentrated regions, astroglial activation, Waller degeneration of the pyramidal tract, neuroinflammation due to CAA related hemorrhages, and possible tau accumulation.