Neuronal Alterations in Secondary Thalamic Degeneration Due to Cerebral Infarction: A 11C-Flumazenil Positron Emission Tomography Study.

BACKGROUND: Studies using animal experiments have shown secondary neuronal degeneration in the thalamus after cerebral infarction. Neuroimaging studies in humans have revealed changes in imaging parameters in the thalamus, remote to the infarction. However, few studies have directly demonstrated neuronal changes in the thalamus in vivo. The purpose of this study was to determine whether secondary thalamic neuronal damage may manifest as a decrease in central benzodiazepine receptors in patients with cerebral infarction and internal carotid artery or middle cerebral artery disease. METHODS: We retrospectively analyzed the data of 140 patients with unilateral cerebral infarction ipsilateral to internal carotid artery or middle cerebral artery disease. All patients had quantitative measurements of 11C-flumazenil binding potential (FMZ-BP), cerebral blood flow, and cerebral metabolic rate of oxygen using positron emission tomography in the chronic stage. Region of interest analysis was performed using NeuroFlexer-an automated region of interest analysis software using NEUROSTAT. RESULTS: In the thalamus ipsilateral to the infarcts, the values of FMZ-BP, cerebral blood flow, and cerebral metabolic rate of oxygen were significantly lower than those in the contralateral thalamus. Significant correlations were found between the ipsilateral-to-contralateral ratio of FMZ-BP and the ipsilateral-to-contralateral ratio of cerebral blood flow or cerebral metabolic rate of oxygen in the thalamus. Patients with corona radiata infarcts and striatocapsular infarcts had significantly decreased ipsilateral-to-contralateral FMZ-BP ratio in the thalamus compared with those without. The ipsilateral-to-contralateral ratio of FMZ-BP in the thalamus was significantly correlated with the ipsilateral-to-contralateral cerebral metabolic rate of oxygen ratio in the frontal cortex and showed a significant negative correlation with the number of perseverative errors on the Wisconsin Card Sorting Test. CONCLUSIONS: Secondary thalamic neuronal damage may manifest as a decrease in central benzodiazepine receptors in patients with cerebral infarction and internal carotid artery or middle cerebral artery disease, which may be associated with frontal lobe dysfunction.

Misery Perfusion and Tau Deposition in Atherosclerotic Major Cerebral Artery Disease: A 18F-Florzolotau Positron Emission Tomography Study.

BACKGROUND: Studies using animal models have shown that cerebral hypoperfusion causes hyperphosphorylation of tau protein, leading to neuronal damage. However, the relationship between hypoperfusion and tau deposition in humans is unclear. Hence, we aimed to determine whether cerebral hypoperfusion leading to decreased blood flow relative to metabolic demand [increased oxygen extraction fraction (OEF), misery perfusion] is associated with increased tau deposition in patients with atherosclerotic internal carotid artery or middle cerebral artery disease. METHODS: We prospectively evaluated the distribution of tau aggregate deposition using positron emission tomography and 18F-florzolotau (PMPBB3 [1-fluoro-3-((2-((1E,3E)-4-(6-(methylamino)pyridine-3-yl)buta-1,3-dien-1-yl)benzo[d]thiazol-6-yl)oxy)propan-2-ol)]) in 8 patients with atherosclerotic disease of the internal carotid artery or middle cerebral artery. The standardized uptake value ratio of 18F-florzolotau at 100 to 110 minutes after injection was calculated using the cerebellar cortex as a reference region and was correlated with OEF obtained from 15O-gas positron emission tomography in the middle cerebral artery distributions. RESULTS: Significant decreases in cerebral blood flow and cerebral metabolic rate of oxygen and increases in OEF were found in the hemisphere ipsilateral to the arterial lesion. 18F-florzolotau standardized uptake value ratio in this region was also greater than that in the contralateral hemisphere. In the ipsilateral hemisphere, 18F-florzolotau standardized uptake value ratio positively correlated with OEF values. CONCLUSIONS: This pilot study with a small sample size suggests that increases in OEF-misery perfusion-may be associated with increased tau aggregates deposition in atherosclerotic internal carotid artery or middle cerebral artery disease.

Visit-to-Visit Blood PressureVariations and Hemodynamic Deterioration in Atherosclerotic Major Cerebral ArteryDisease.

OBJECTIVE: Visit-to-visit variations in blood pressure (BP) in patients with atherosclerotic major cerebral artery disease could impair the function of cerebral collaterals, leading to hemodynamic deterioration at follow-up. However, few studies have investigated the relationship between visit-to-visit BP variability and changes in hemodynamic parameters at follow-up. MATERIALS AND METHODS: We evaluated 35 medically treated patients with atherosclerotic internal carotid artery or middle cerebral artery disease with no ischemic episodes during follow-up (mean: 35 ± 20 months); these patients had a three-time visit for positron emission tomography examinations with 15O-gas. Differences in the mean hemispheric values of hemodynamic parameters in the cortical territory of the diseased artery between the first and third examinations (changes at follow-up) were correlated with the coefficient of variation (CoV) in three systolic BP (SBP) values at the three examinations (BP variability during follow-up). RESULTS: CoV values were negatively correlated with changes in oxygen metabolism or cerebral blood flow/cerebral blood volume (CBF/CBV) ratio. In 17 patients with higher CoV values (> group median, 0.072), decreases in CBF, cerebral metabolic rate of oxygen, and CBF/CBV ratio were observed at follow-up; CBV decreased in 18 patients without elevated CoV. A higher CoV was associated with a lack of statin use. CONCLUSION: In patients with atherosclerotic major cerebral artery disease, high visit-to-visit SBP variations during follow-up may be associated with deterioration in cerebral hemodynamics and metabolism.

Selective neuronal damage and blood pressure in atherosclerotic major cerebral artery disease.

OBJECTIVE: In patients with atherosclerotic major cerebral artery disease, low blood pressure might impair cerebral perfusion, thereby exacerbate the risk of selective neuronal damage. The purpose of this retrospective study was to determine whether low blood pressure at follow-up is associated with increased selective neuronal damage. METHODS: We retrospectively analysed data from 76 medically treated patients with atherosclerotic internal carotid artery or middle cerebral artery disease with no ischaemic episodes on a follow-up of 6 months or more. All patients had measurements of the distribution of central benzodiazepine receptors twice using positron emission tomography and 11C-flumazenil. Using three-dimensional stereotactic surface projections, we quantified abnormal decreases in the benzodiazepine receptors of the cerebral cortex within the middle cerebral artery distribution and correlated these changes in the benzodiazepine receptors index with blood pressure values at follow-up examinations. RESULTS: The changes in the benzodiazepine receptor index during follow-up (mean 27±21 months) were negatively correlated with systolic blood pressure at follow-up. The relationship between changes in benzodiazepine receptor index and systolic blood pressure was different among patients with and without decreased cerebral blood flow at baseline (interaction, p<0.005). Larger increases in benzodiazepine receptor index (neuronal damage) were observed at lower systolic blood pressure levels in patients with decreased cerebral blood flow than in patients without such decreases. CONCLUSION: In patients without ischaemic stroke episodes at follow-up but with decreased cerebral blood flow due to arterial disease, low systolic blood pressure at follow-up may be associated with increased selective neuronal damage.

18 F-FDG PET/CT Findings of Surgically Transposed Ovaries After Radical Hysterectomy in a Young Adult Patient.

ABSTRACT: A 35-year-old woman underwent 18 F-FDG PET/CT 2 months after a radical hysterectomy for uterine cervical cancer. An apparent FDG uptake was observed in an oval-shaped mass with an attached surgical clip in the right paracolic gutter. A similar non-FDG-avid mass with a clip was observed in the left. In this case, ovarian transposition had also been performed with metallic clips placed on both sides of the paracolic gutters. The increased FDG uptake in the right paracolic gutter was interpreted as physiological uptake in the right transposed ovary, not metastasis. Recognizing the possibility of FDG uptake in transposed ovaries is important.

New objective simple evaluation methods of amyloid PET/CT using whole-brain histogram and Top20%-Map.

OBJECTIVE: This study aims to assess the utility of newly developed objective methods for the evaluation of intracranial abnormal amyloid deposition using PET/CT histogram without use of cortical ROI analyses. METHODS: Twenty-five healthy volunteers (HV) and 38 patients with diagnosed or suspected dementia who had undergone 18F-FPYBF-2 PET/CT were retrospectively included in this study. Out of them, 11C-PiB PET/CT had been also performed in 13 subjects. In addition to the conventional methods, namely visual judgment and quantitative analyses using composed standardized uptake value ratio (comSUVR), the PET images were also evaluated by the following new parameters: the skewness and the mode-to-mean ratio (MMR) obtained from the histogram of the brain parenchyma; Top20%-map highlights the areas with high tracer accumulation occupying 20% volume of the total brain parenchymal on the individual's CT images. We evaluated the utility of the new methods using histogram compared with the visual assessment and comSUVR. The results of these new methods between 18F-FPYBF-2 and 11C-PiB were also compared in 13 subjects. RESULTS: In visual analysis, 32, 9, and 22 subjects showed negative, border, and positive results, and composed SUVR in each group were 1.11 ± 0.06, 1.20 ± 0.13, and 1.48 ± 0.18 (p < 0.0001), respectively. Visually positive subjects showed significantly low skewness and high MMR (p < 0.0001), and the Top20%-Map showed the presence or absence of abnormal deposits clearly. In comparison between the two tracers, visual evaluation was all consistent, and the ComSUVR, the skewness, the MMR showed significant good correlation. The Top20%-Maps showed similar pattern. CONCLUSIONS: Our new methods using the histogram of the brain parenchymal accumulation are simple and suitable for clinical practice of amyloid PET, and Top20%-Map on the individual's brain CT can be of great help for the visual assessment.

Neural correlates of the components of the clock drawing test.

BACKGROUND: The aim of this study was to identify the neural correlates of each component of the clock drawing test (CDT) in drug-naïve patients with Alzheimer's disease (AD) using single photon emission computed tomography. METHODS: The participants were 95 drug-naïve patients with AD. The Rouleau CDT was used to score the clock drawings. The score for the Rouleau CDT (R total) is separated into three components: the scores for the clock face (R1), the numbers (R2), and the hands (R3). A multiple regression analysis was performed to examine the relationship of each score (i.e. R total, R1, R2, and R3) with regional cerebral blood flow (rCBF). Age, gender, and education were included as covariates. The statistical threshold was set to a family-wise error (FWE)-corrected p value of 0.05 at the voxel level. RESULTS: The R total score was positively correlated with rCBF in the bilateral parietal and posterior temporal lobes and the right middle frontal gyrus. R1 was not significantly positively correlated with rCBF, R2 was significantly positively correlated with rCBF in the right posterior temporal lobe and the left posterior middle temporal lobe, and R3 was significantly positively correlated with rCBF in the bilateral parietal lobes, the right posterior temporal lobe, the right middle frontal gyrus, and the right occipital lobe. CONCLUSIONS: Various brain regions were associated with each component of the CDT. These results suggest that an assessment of these components is useful for the detection of localization of brain damage.

FDG-PET findings associated with various medical procedures and treatments.

[18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a well-established modality with high sensitivity for the diagnosis and staging of oncologic patients. FDG is taken up by the glucose transporter of the cell membrane and becomes trapped within the cell. In addition to malignant neoplasms, active inflammatory lesions and some kinds of benign tumors also accumulate FDG. Moreover, the degree of uptake into normal organs and tissues depends on various physiological conditions, which is affected by various medical procedures, treatments, and drugs. To avoid misleading interpretations, it is important to recognize possible situations of unexpected abnormal accumulation that mimic tumor lesions. In this review, we present various FDG findings associated with surgical or medical procedures and treatments. Some findings reflect the expected physiological reaction to treatment, and some show inflammation due to prior procedures. Occasionally, FDG-PET visualizes other disorders that are unrelated to the malignancy, which may be associated with the adverse effects of certain drugs that the patient is taking. Careful review of medical records and detailed interviews of patients are thus necessary.

Characteristic Muscular FDG Uptake Patterns Related to the Transportation Means Used by Patients to Visit the Hospital.

ABSTRACT: It is well-known that physiological FDG uptake in the skeletal muscles is affected by serum insulin levels and the extent to which the muscles contract before the examination. Patients are instructed to refrain from strenuous exercise, talking too much, and taking meals at least 4 hours before the administration of the tracer. Even if the patient does not intend to exercise, muscular accumulation related to specific behaviors can still be visualized in the images. In this manuscript, we present FDG PET/CT images from 4 cases reflecting the mode of transportation used by the patients to visit the hospital.

Radiation dosimetry and pharmacokinetics of the tau PET tracer florzolotau (18F) in healthy Japanese subjects.

OBJECTIVE: Abnormal aggregation of tau in the brain is a major contributing factor in various neurodegenerative diseases. Florzolotau (18F) (florzolotau, APN-1607, PM-PBB3) has been shown to be a probe for tau fibrils in an animal model and patients with Alzheimer's disease and those with non-Alzheimer's disease tauopathies. The objective of this study is to evaluate the safety, pharmacokinetics, and radiation dose following a single intravenous administration of florzolotau in healthy Japanese subjects. METHODS: Three healthy male Japanese subjects aged between 20 and 64 were enrolled in this study. Subjects were determined to be eligible based on the screening assessments at the study site. Subjects received a single intravenous dose of 195.0 ± 0.5 MBq of florzolotau and underwent the whole-body PET scan 10 times in total to calculate absorbed doses to major organs/tissues and effective dose. Radioactivities in whole blood and urine were also measured for pharmacokinetic evaluation. Absorbed doses to major organs/tissues and effective dose were estimated using the medical internal radiation dose (MIRD) method. Vital signs, electrocardiography (ECG), and blood tests were done for safety evaluation. RESULTS: The intravenous injection of florzolotau was well tolerated. There were no adverse events or clinically detectable pharmacologic effects related to the tracer in any subjects. No significant changes in vital signs and ECG were observed. The highest mean initial uptake at 15 min after injection was in the liver (29.0 ± 4.0%ID), intestine (4.69 ± 1.65%ID), and brain (2.13 ± 0.18%ID). The highest absorbed dose was 508 µGy/MBq of the gallbladder wall, followed by the liver of 79.4 µGy/MBq, the pancreas of 42.5 µGy/MBq, and the upper large intestine of 34.2 µGy/MBq. The effective dose was calculated as 19.7 µSv/MBq according to the tissue weighting factor reported by ICRP-103. CONCLUSION: Florzolotau intravenous injection was well tolerated in healthy male Japanese subjects. The effective dose was determined as 3.61 mSv when 185 MBq florzolotau was given.

Simultaneous impairment of intracranial and peripheral artery vasoreactivity in CADASIL patients.

BACKGROUND: Reduced cerebrovascular reactivity (CVR) is an important step in the pathogenesis of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). The present study utilized quantitative single photon emission computed tomography (SPECT) with the autoradiographic (ARG) method and reactive hyperemia peripheral arterial tonometry (RH-PAT) to assess vasoreactivity in intracranial arteries and in peripheral arteries in patients with CADASIL. METHODS: Quantitative SPECT studies were conducted in eight patients with CADASIL, while RH-PAT analysis was conducted in eight CADASIL patients and in eight age-matched normal subjects. Quantitative SPECT studies with the ARG method were performed at baseline and after administration of acetazolamide. Regional cerebral blood flow (rCBF) values were measured using stereotactic extraction estimation (SEE) methods. The rCBF of CADASIL patients was averaged in the bilateral frontal, temporal, parietal, and occipital lobes as well as in the limbic system, cerebellar hemisphere, whole cerebral cortex and basal ganglia. The CVR index from acetazolamide stress of intracranial arteries was calculated in each area. Vasoreactivity of peripheral arteries was estimated by the reactive hyperemia index (RHI) measured with a PAT device before and after interruption of arterial flow. RESULTS: Average RHI after post-deflation was lower in CADASIL patients than in normal subjects. RHI correlated significantly with CVR in all brain areas in CADASIL patients. CONCLUSIONS: Vasoreactivity is reduced in peripheral arteries and in intracranial arteries in patients with CADASIL.

Cardiac event risk in Japanese subjects estimated using gated myocardial perfusion imaging, in conjunction with diabetes mellitus and chronic kidney disease.

BACKGROUND: Cardiac event risk is estimated using quantitative gated myocardial perfusion imaging (MPI) and clinical background in patients with ischemic heart disease. The aim of the present study was to calculate major cardiac event risk and tabulate it in the Heart Risk Table for clinical use of risk stratification. METHODS AND RESULTS: Multivariate logistic regression was performed based on a multicenter prognostic database (Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated Single-photon emission computed tomography [J-ACCESS investigation]) using MPI (n=2,395). The risk of major cardiac events (cardiac death, non-fatal myocardial infarction and heart failure requiring hospitalization) was estimated using age, ejection fraction (EF), estimated glomerular filtration rate (eGFR) and presence of diabetes mellitus (DM). Age-matched standard eGFR was determined in 77 subjects. Major cardiac event risk was calculated using the equation: risk (%/3 years)=1/(1+Exp(-(-4.699-0.0151×eGFR+0.7998×DM+0.0582×age+0.697×SSS-0.0359×EF))×100, where SSS refers to summed stress scores. Risk was determined without eGFR (the initial version) and using the present formula with eGFR (revised version), with consistent results. DM and chronic kidney disease were major determinants of cardiac events. CONCLUSIONS: Cardiac event risk was estimated using MPI defect score and left ventricular EF in conjunction with eGFR and the presence of DM. The risk table might be used for risk evaluation in Japanese patients undergoing MPI.

Physiologically decreased F-18 fluorodeoxyglucose uptake in the lower vertebrae associated with daily drinking habit in Japanese men with alcohol flushing reaction.

Alcohol flushing reaction (AFR) is known as one of the risks for esophageal squamous cell cancer, and scientists have been elucidating this issue. However, little attention has been given to relevant imaging features. This study aims to investigate whether physiological 18F-fluorodeoxyglucose (FDG) uptake patterns in vertebrae are associated with drinking habits or AFR. Japanese male patients who underwent FDG positron emission computed tomography for evaluation of their known or suspected malignancies or inflammatory diseases were asked about their drinking habits and AFR. Altogether, 192 patients, 139 every-day drinkers and 53 non-drinkers were evaluated. Comparing the FDG uptake between that in the thoracic region and that in the lumbar region, vertebral uptake was visually classified into four patterns: Ld, dominant in lumbar region; TL, almost equal in both regions; BL, slightly higher in thoracic region (borderline pattern); Td, dominant in thoracic region. The uptake patterns were evaluated according to drinking habit (every-day drinker or non-drinker), AFR (flusher or non-flusher), and the combination of these two factors (habit/reaction: every-day drinker/flusher, every-day drinker/non-flusher, non-drinker/flusher, or non-drinker/non-flusher). There were 95 flushers (51 every-day drinkers and 44 non-drinkers) and 97 non-flushers (88 every-day drinkers and 9 non-drinkers). Ld, TL, BL, and Td patterns were observed in 0, 109 (56.8%), 31 (16.1%), and 52 (27.1%) patients, respectively. Td and BL patterns were more frequently observed in every-day drinkers compared with non-drinkers (p = 0.0467). Though the uptake patterns did not differ between flushers and non-flushers (p = 0.116), the Td pattern was more frequently observed in every-day drinkers/flushers (51%) compared with every-day drinkers/non-flushers (20.5%), non-drinkers/flushers (13.6%), and non-drinkers/non-flushers (22.2%) (p = 0.0014). The Td pattern was observed in patients with various diseases, with higher frequency in esophageal cancer, head and neck cancer, and lung cancer compared with other diseases. In conclusion, drinking habits and AFR were related to the vertebral uptake pattern with decreased uptake in the lumbar region in Japanese male patients.

Insular hypoperfusion correlates with the severity of delusions in individuals with Alzheimer's disease.

BACKGROUND: The aim of this study was to identify the brain regions associated with the severity of delusions in individuals with Alzheimer's disease (AD) using single-photon emission computed tomography. METHODS: Thirty-five AD patients participated in this study. Multiple regression analysis was performed to identify a linear correlation between the delusion subscale score of the Neuropsychiatric Inventory (NPI) and regional cerebral blood flow (rCBF) in AD patients with delusions (n = 14). In addition, rCBF in patients with (n = 14) and without delusions (n = 21) was compared using a 2-sample t test. RESULTS: The delusion subscale score of the NPI was negatively correlated with rCBF in the right anterior insula (uncorrected p < 0.01 at the voxel level and corrected p < 0.05 at the cluster level). Compared to patients without delusions, however, rCBF in the right anterior insula was not significantly decreased in patients with delusions. CONCLUSION: We suggest that right anterior insular dysfunction may exacerbate delusions, although it is not responsible for the onset of delusions.

Unusual fatty metamorphosis observed in diffuse liver metastases of stage 4S neuroblastoma.

We report a case of stage 4S neuroblastoma in which CT showed diffuse liver metastases containing a geographical fatty area in the periportal region. MRI showed this abnormality to correspond to an area with an unusual pattern of fatty change. (123)I-metaiodobenzylguanidine (MIBG) scintigraphy demonstrated increased accumulation throughout the liver, except for the region showing fatty change. To the best of our knowledge, this is the first report of liver metastases from neuroblastoma with geographical fatty infiltration.

FDG Uptake in Brown Adipose Tissue Activated by a ß3-Adrenergic Receptor Agonist Prescribed for Overactive Bladder.

Brown adipose tissue (BAT), which produces energy and is known to play a role as a hibernating gland, is sometimes visualized on F-FDG PET in children or in slender young adults in a cold environment. Because BAT is activated by catecholamines, FDG uptake in BAT is also observed in patients with pheochromocytoma or paraganglioma. We present the case of an elderly woman with remarkable FDG uptake in BAT. Activation of BAT by a ß3-adrenergic receptor agonist (mirabegron) prescribed for overactive bladder was suspected as the cause of the marked visualization of BAT in this patient.

Complete Spontaneous Regression of Hepatosplenic T-Cell Lymphoma After Surgical Biopsy.

F-FDG PET/CT for a 74-year-old man with elevated serum soluble interleukin 2 receptor showed multiple intense uptake in the liver, spleen, and bone. A surgical biopsy from 2 of liver tumors confirmed hepatosplenic αß T-cell lymphoma. One and a half months after biopsy, FDG PET scan was performed again for staging before starting chemotherapy, and it showed the complete disappearance of all of the lesions. The excisional biopsy could be a possible trigger of his spontaneous regression.

Predominance and homogeneity patterns of physiological FDG accumulation in thoracic and lumbar vertebrae: suspected mechanism of "bone pseudometastasis" on FDG-PET in Japanese patients with esophageal cancer.

OBJECTIVE: False-positive bone lesions (bone pseudometastases) have been often reported in patients with esophageal cancer (EsoC). This study aimed to evaluate the vertebral 2-deoxy-2-[18F] fluoro-D-glucose (FDG) accumulation pattern in patients with newly diagnosed esophageal cancers and other malignancies (OtherT) to elucidate the possible mechanism that causes bone pseudometastasis. METHODS: FDG positron emission tomography/computed tomography performed for 90 patients with EsoC, and 112 patients with OtherT was retrospectively evaluated. The uptake pattern in the thoracic (Th) and lumbar (L) vertebrae was visually assessed regarding predominance (TL, Th ≒ L; Td, Th > L; Ld, L > Th), main intensity compared with the uptake in the blood pool (BP) (Grade 1 < BP, Grade 2 ≒ BP, or Grade 3 > BP), and homogeneity (homogeneous, heterogeneous, marginal, or spotty). The patterns between EsoC and OtherT and between Th and L were compared. RESULTS: TL, Td, and Ld patterns were observed in 51.1%, 48.9%, and 0% in EsoC and 79.7%, 20.3%, and 0% in OtherT. Though Grade 2 was most frequently observed in both groups, the ratio of Grade 3 in Th and Grade 1 in L was significantly higher in EsoC than in OtherT. Heterogeneous and spotty patterns were more frequently observed in L and in EsoC, and these were strongly associated with Td pattern. CONCLUSION: Td pattern was frequently seen, especially in EsoC, and was strongly associated with a heterogeneous or marginal pattern in the L. Heterogeneous marrow distribution with declined lumbar uptake is suspected as the mechanism of bone pseudometastasis.