Publications by authors named "Kyoungjune Pak"

121 Publications

Smaller hippocampal volume in APOE ε4 carriers independent of amyloid-β (Aβ) burden.

Psychiatry Res Neuroimaging 2021 Aug 30;317:111381. Epub 2021 Aug 30.

Department of Psychiatry, Pusan National University School of Medicine, Yangsan, Republic of Korea.

Objective: To investigate the association of the APOE ε4 genotype with hippocampal volume, independent of Aβ burden.

Method: This cross-sectional study included 71 participants with mild cognitive impairment or mild AD. All participants were divided into carriers or non-carriers of the ε4 allele. The main outcome was hippocampal volume measured using structural magnetic resonance imaging; F-florbetaben positron emission tomography was additionally performed to investigate the association of APOE ε4 genotype with hippocampal volumes, independently of Aβ burden. Analysis of covariance was conducted to compare the differences in hippocampal volumes between carriers and non-carriers of the ε4 allele after controlling for global Aβ burden or local hippocampal Aβ burden.

Results: The APOE ε4 genotype was associated with a smaller right and total hippocampal volume (right: 3160.16 ± 365.71 vs. 3365.24 ± 434.88, p < 0.05; total: 6257.48 ± 790.60 vs. 6599.52 ± 840.58, p < 0.05), independent of Aβ burden.

Conclusion: Our findings on the association of APOEε4 genotype with hippocampal volume independent of Aβ burden suggest that the APOEε4 genotype may contribute to hippocampal neurodegeneration through an Aβ-independent mechanism.
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http://dx.doi.org/10.1016/j.pscychresns.2021.111381DOI Listing
August 2021

Striatal DAT availability does not change after supraphysiological dose of glucose loading in humans.

Endocr Connect 2021 Sep 1. Epub 2021 Sep 1.

I Kim, Pusan National University Hospital, Busan, Korea (the Republic of).

Brain dopamine neurotransmission is regulated by dopamine transporter (DAT), which drives reuptake of extracellular dopamine into the presynaptic neurons. We hypothesized that the dose of glucose loading would affect the striatal DAT availability. An intravenous bolus injection of 18F-FP-CIT was administered after infusion of low-dose glucose (300 mg/kg), high-dose glucose (600 mg/kg) or placebo (normal saline). The emission data were acquired over 90 mins in 23 healthy male subjects. Substantial increases of binding potential (BPNDs) from ventral striatum (VST), caudate nucleus, and putamen were observed after low-dose glucose loading (+26.0%, +87.0%, and +37.8%), and after high-dose glucose loading (+10.4%, +51.9%, and +22.0%). BPNDs of the caudate nucleus and putamen showed significant differences (p=0.0472 and 0.0221) after placebo, low-dose glucose, and high-dose glucose loading. BPNDs in the caudate nucleus and putamen after placebo, low-dose glucose, and high-dose glucose loading were positively intercorrelated with each other. In conclusion, striatal DAT changes after physiological glucose loading, but not after supraphysiological glucose loading in humans. DAT availabilities after placebo, low-dose glucose, high-dose glucose loading were correlated each other in the caudate nucleus and putamen, but not in the VST. Therefore, sub-regional variability in DAT regulatory mechanisms mediated by insulin may exist in humans.
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http://dx.doi.org/10.1530/EC-21-0355DOI Listing
September 2021

Effects of Photobiomodulation on Changes in Cognitive Function and Regional Cerebral Blood Flow in Patients with Mild Cognitive Impairment: A Pilot Uncontrolled Trial.

J Alzheimers Dis 2021 Aug 14. Epub 2021 Aug 14.

Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.

Background: Photobiomodulation (PBM) affects local blood flow regulation through nitric oxide generation, and various studies have reported on its effect on improving cognitive function in neurodegenerative diseases. However, the effect of PBM in the areas of the vertebral arteries (VA) and internal carotid arteries (ICA), which are the major blood-supplying arteries to the brain, has not been previously investigated.

Objective: We aimed to determine whether irradiating PBM in the areas of the VA and ICA, which are the major blood-supplying arteries to the brain, improved regional cerebral blood flow (rCBF) and cognitive function.

Methods: Fourteen patients with mild cognitive impairments were treated with PBM. Cognitive assessment and single-photon emission computed tomography were implemented at the baseline and at the end of PBM.

Results: Regarding rCBF, statistically significant trends were found in the medial prefrontal cortex, lateral prefrontal cortex, anterior cingulate cortex, and occipital lateral cortex. Based on the cognitive assessments, statistically significant trends were found in overall cognitive function, memory, and frontal/executive function.

Conclusion: We confirmed the possibility that PBM treatment in the VA and ICA areas could positively affect cognitive function by increasing rCBF. A study with a larger sample size is needed to validate the potential of PBM.
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http://dx.doi.org/10.3233/JAD-210386DOI Listing
August 2021

Prognostic value of SUVmax in breast cancer and comparative analyses of molecular subtypes: A systematic review and meta-analysis.

Medicine (Baltimore) 2021 Aug;100(31):e26745

Department of Surgery, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.

Background: To assess the prognostic capability of the maximum standardized uptake values (SUVmax) measured in the primary tumor and axillary lymph nodes (ALNs) by pretreatment fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography and analyze outcomes according to the molecular breast cancer subtypes.

Methods: The databases were systematically searched using keywords for breast cancer, positron emission tomography/computed tomography, and SUVmax; the extracted studies reported at least 1 form of survival data, event-free survival (EFS) and overall survival. Comparative analyses of the pooled hazard ratios (HRs) for EFS and overall survival were performed to assess their correlations with SUVmax. The pooled HR was estimated using random-effects model according to the results of heterogeneity.

Results: Thirteen eligible studies comprising 3040 patients with breast cancer were included. The pooled HRs of high SUVmax in the primary tumor and ALN were 3.01 (95% CI 1.83-4.97, P < .00001; I2 = 82%) and 3.72 (95% CI 1.15-12.01; I2 = 92%; P = .03), respectively. Patients with higher SUVmax demonstrated a poorer survival prognosis. Furthermore, comparative analyses according to the molecular subtypes demonstrated that the SUVmax in the primary tumor or ALN can be a predictive parameter in patients with the luminal subtype disease. Subtype analysis results indicated a significant association of the luminal group, with a HR of 2.65 (95% CI 1.31-5.37; I2 = 27%; P = .007).

Conclusions: SUVmax from pretreatment is a significant prognostic factor for EFS in patients with breast cancer. Despite several limitations, correlation with molecular subtype (luminal type) was demonstrated. Further large-scale studies are required to investigate the precise prognostic capability of SUVmax.
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http://dx.doi.org/10.1097/MD.0000000000026745DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8341324PMC
August 2021

No effect of Parkinson's disease-polygenic load on striatal density of dopaminergic neuron in healthy subjects.

Ann Nucl Med 2021 Jul 21. Epub 2021 Jul 21.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, 179 Gudeok-ro, Seo-gu, Busan, 49241, Republic of Korea.

Objective: There has been increasing evidence to support the role of genetic factors in Parkinson's disease (PD). I-FP-CIT single-photon emission computed tomography (SPECT) enables in vivo visualization of the striatal density of dopaminergic neuron.

Methods: We investigated the association between PD-associated polygenic load and striatal density of dopaminergic neuron in healthy subjects. Data used in the preparation of this article were obtained from Parkinson's Progression Markers Initiative database. I-FP-CIT SPECT was performed for all subjects. Specific binding ratios (SBRs) were calculated from the ventral striatum, caudate nucleus, and putamen with reference to cerebellum. Singe nucleotide polymorphism (SNP) genotyping from the PPMI database was adopted in calculating genetic risk score (GRS). GRS was defined as the sum of the number of risk alleles weighted by log odds ratios for PD. We calculated three GRSs using three different sets of SNPs.

Result: A total of 151 subjects were included in this study (101 males, 50 females). GRS1, GRS2 and GRS3 were significantly different with the highest scores of GRS1. Multiple regression was done to investigate whether striatal SBRs are influenced by GRSs after adjusting for age and sex. However, none of GRSs were associated with SBRs of the ventral striatum, caudate nucleus and putamen.

Conclusion: PD risk SNPs weighted by odds ratio for PD were not associated with SBRs measured from SPECT in healthy subjects. Therefore, there is no effect of PD-associated polygenic load on striatal density of dopaminergic neuron in healthy subjects.
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http://dx.doi.org/10.1007/s12149-021-01657-wDOI Listing
July 2021

No association of Brain-derived neurotrophic factor with striatal dopamine transporter availability in healthy subjects.

Nuklearmedizin 2021 Jul 13. Epub 2021 Jul 13.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Korea (the Republic of).

Objective: Brain-derived neurotrophic factor (BDNF) is a neurotrophin that plays a key role in brain plasticity, synaptic function, neuronal survival, learning, and memory formation. We aimed to investigate the association of BDNF with dopamine transporter (DAT) availabilities measured by positron emission tomography (PET) in healthy subjects.

Methods: Thirty-five healthy, male subjects without brain injury, neuropsychological disorders were included in this study. The emission data were acquired over 90 mins with 50 frames after injection of 18F-FP-CIT using PET. Binding potentials (BPNDs) of ventral striatum (VST), caudate nucleus, putamen were measured with the simplified reference tissue method. The serum BDNF level (pg/mL) was measured through enzyme-linked immunosorbent assay method.

Results: Thirty-five healthy males with a mean age of 24.4 ± 2.7 years were included in this study. Multiple regression was done to investigate the association between striatal BPNDs from VST, caudate nucleus, putamen and serum BDNF after adjusting for age. None of striatal BPNDs from VST (p=0.8450), caudate nucleus (p=0.4783), and putamen (p=0.7994) were associated with serum BDNF.

Conclusion: Striatal DAT availabilities measured from PET were not associated with the serum BDNF in healthy subjects.
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http://dx.doi.org/10.1055/a-1521-8572DOI Listing
July 2021

The association of DAT gene methylation with striatal DAT availability in healthy subjects.

EJNMMI Res 2021 Jun 12;11(1):58. Epub 2021 Jun 12.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, 179 Gudeok-ro, Seo-gu, Busan, 49241, Republic of Korea.

Background: DNA methylation inhibits gene expression by preventing transcription factors from binding to DNA. Functioning of nigrostriatal dopaminergic neurons is influenced by the expression of the dopamine transporter (DAT), and genetic variations in the gene encoding DAT contribute to differences in reward processing. We aimed to investigate the action of DAT methylation on DAT protein expression measured by positron emission tomography (PET).

Methods: The emission data were acquired over 90 min with 50 frames after injection of F-FP-CIT using PET. Binding potentials (BPs) of ventral striatum, caudate nucleus, putamen were measured with the simplified reference tissue method. Genomic DNA was extracted from subjects' blood sampling. Methylation of 4 regions in SLC6A3 gene was assessed using bisulfite pyrosequencing. The mean percentage of methylation (%) for each cluster was calculated by taking the average of all CpG site methylation levels measured within the cluster. Subjects were assessed with the Generalized Reward and Punishment Expectancy Scales (GRAPES) that consists of 30 items related with the reward and punishment that individuals expect for their behaviors.

Results: Thirty-five healthy males, with an age range between 20 and 30 years, and a mean age of 24.4 ± 2.7 years, were included in this study. The mean percentage of methylation (%) from cluster C showed a trend of positive correlation with DAT availability of ventral striatum (rho = 0.3712, p = 0.0281), not significant after correction for multiple comparisons, and a significant correlation with GRAPES A: reward expectancy scale (rho = 0.7178, p < 0.0001).

Conclusion: DAT methylation from peripheral blood showed a trend of positive correlation with DAT availability of ventral striatum in healthy subjects; however, it was not significant after correction for multiple comparison. The degrees of methylation from cluster C of DAT in peripheral blood were significantly correlated with reward scales of GRAPES A: reward expectancy scale. The association between DAT methylation and DAT expression needs to be investigated further.
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http://dx.doi.org/10.1186/s13550-021-00800-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8197693PMC
June 2021

Spine-Hip Discordance and FRAX assessment Fracture Risk in Postmenopausal Women with Osteopenia from Concordant Diagnosis Between Lumbar Spine and Femoral Neck.

J Clin Densitom 2021 Apr 6. Epub 2021 Apr 6.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea. Electronic address:

The diagnostic criteria proposed by the World Health Organization did not consider the discrepancy in diagnosis between lumbar spine (LS) and femoral neck (FN) and the clinical implications is unclear. Therefore, this retrospective study evaluated the probability of fracture risk in postmenopausal women with lumbar spine (LS)-femoral neck (FN) bone mineral density (BMD) discordance or not Patients included 1066 healthy postmenopausal women (median age 55.5 years) who visited our hospital for a health check-up between May 2013 and April 2017. Discordance was defined as a difference of one or two degrees between LS BMD and FN BMD. TBS was calculated from dual energy absorptiometry (DXA) images. Fracture risk was assessed using the Fracture Risk Assessment Tool (FRAX), including TBS-adjusted FRAX Seven hundred and two patients (65.9%) showed concordant LS and FN results, whereas 364 patients (34.1%) exhibited discordance. Normal BMD was found in 519 concordant patients (73.9%). Concordant patients showed significantly higher FRAX scores, including TBS-adjusted FRAX results, than discordant patients with low LS or FN. Furthermore, FRAX results in concordant osteopenia patients were similar to that of osteoporosis patients with osteopenia or a normal result at one site. FRAX and TBS-adjusted FRAX results in concordant osteopenia patients were comparable to that of discordant osteoporosis patients We concluded that patients with colncordant osteopenia in both the FN and LS should be managed in a similar way to patients with discordant osteoporosis.
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http://dx.doi.org/10.1016/j.jocd.2021.03.008DOI Listing
April 2021

Effect of tamoxifen with or without gonadotropin-releasing hormone analog on DXA values in women with breast cancer.

Sci Rep 2021 Feb 9;11(1):3407. Epub 2021 Feb 9.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.

The purpose of this study was to compare the changes in DXA values including trabecular bone score (TBS) and bone mineral density (BMD) of lumbar spine (LS) and femur according to the hormone therapies including tamoxifen (TMXF) treatment with or without gonadotropin releasing hormone analog (GnRH analog) in women with breast cancer. We enrolled 119 women with breast cancer who had undergone breast-conserving surgery or mastectomy followed by TMXF treatment for postmenopausal women (TMXF group, n = 63, 52.9%) or by combination therapy of TMXF combined with GnRH analog for premenopausal women (TMXF + GnRH group, n = 56, 47.1%) from December 2013 to December 2017. The median follow-up period was 13 months (interquartile range [IQR], 12.0-14.75) for TMXF group and 13.5 months (IQR, 12.00-16.00) for TMXF + GnRH group, respectively. Patients did not receive bone-modifying therapy. The baseline dual-energy X-ray absorptiometry (DXA) scan before breast cancer surgery and follow-up DXA during hormone therapy. Comparing the first and follow-up DXA results, BMD in LS were significantly decreased in both TMXF (P < 0.001, mean difference: - 0.06) and TMXF + GnRH (P < 0.001, mean difference: - 0.09) groups. BMD values of femoral neck (P = 0.0011, mean difference: - 0.01) and total femur (P < 0.001, mean difference: - 0.03) was significantly changed between the baseline and follow-up DXA in TMXF + RnRH group. In the TMX group, a significant changed occurred in the BMD in total femur (P < 0.001, mean difference: - 0.030) but not the BMD of femoral neck (P = 0.095, mean difference: - 0.007). Regarding TBS, no significant change was found in the TMXF (P = 0.574, mean difference: - 0.004) group, whereas there was a significant decrease in TBS in the TMXF + GnRH (P < 0.001, mean difference: - 0.02) group during follow-up. TBS is more sensitive in reflecting the bone microarchitecture changes by TMXF or GnRH agonist in breast cancer patients than BMD. This finding demonstrates that TBS can be a useful parameter to detect bone microarchitectural changes in clinical applications.
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http://dx.doi.org/10.1038/s41598-021-82824-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7873035PMC
February 2021

Sex difference in cerebral blood flow and cerebral glucose metabolism: an activation-likelihood estimation meta-analysis.

Nucl Med Commun 2021 Apr;42(4):410-415

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.

Objectives: Sex differences exist in a variety of aspects including neurochemicals as well as behavioral traits of cognition, language, and aggression. We performed a meta-analysis of studies using a coordinate-based technique of activation-likelihood estimation (ALE) to identify the pooled estimated effect of sex difference.

Methods: We performed a systematic search of MEDLINE and EMBASE for English-language publications using the keywords of 'positron emission tomography (PET)', 'single-photon emission computed tomography (SPECT)', and 'sex'. A threshold of uncorrected P < 0.001 (minimum volume of 200 mm3) was applied to the resulting ALE map.

Results: Cerebral blood flow (CBF) in right precuneus, left superior temporal gyrus, left inferior temporal, left inferior frontal gyrus, right cerebellar tonsil, and right middle temporal gyrus was higher in females than males. CBF in left anterior cingulate was higher in males than females. Whereas, the cerebral metabolic rate for glucose (CMRglu) in left thalamus, left cingulate gyrus, right inferior parietal lobule, left medial frontal gyrus, right middle frontal gyrus, right midbrain, and left inferior parietal lobule was higher in females than males. However, there was no brain region that showed higher CMRglu in males than females.

Conclusion: Regional CBF and CMRglu from PET and SPECT showed the difference between males and females.
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http://dx.doi.org/10.1097/MNM.0000000000001343DOI Listing
April 2021

Recent Survey of Effective Doses of F-18 FDG Torso PET/CT in Korea and the Current Recommendations for CT Protocols of PET/CT.

Nucl Med Mol Imaging 2020 Oct 20;54(5):224-232. Epub 2020 Jul 20.

Department of Nuclear Medicine, National Cancer Center, Goyang-si, South Korea.

Purpose: This study aimed to construct a database of the effective doses (ED) from F-18 fluorodeoxyglucose (FDG) torso positron emission tomography/computed tomography (PET/CT) in Korea to provide data that supports the reduction of the CT dose of PET/CT and optimization of PET/CT protocols in Korea.

Methods: We investigated data of ED and CT parameters of FDG PET/CT. The data were analyzed by body weight groups.

Results: A total of 31 hospitals participated in the survey (99 adults). The mean total EDs (± SD) were 8.77 ± 2.76, 10.93 ± 3.14, and 12.57 ± 3.79 mSv for the 55-, 70-, and 85-kg groups, respectively. The FDG EDs were 4.80 ± 0.98, 6.05 ± 1.15, and 6.89 ± 1.52 mSv, and the CT EDs were 4.00 ± 2.12, 4.88 ± 2.51, and 5.68 ± 2.89 mSv, respectively. Of the enrolled hospitals, 54.5% used ultra-low-dose CT protocols, and their CT ED was significantly lower than low-dose CT group in all groups (2.9 ± 1.0, 3.2 ± 1.1, and 3.3 ± 1.0 mSv vs. 6.6 ± 1.6, 7.2 ± 2.1, and 7.9 ± 2.2 mSv, all  < 0.001, respectively). In the ultra-low-dose CT group, the CT ED with the iterative reconstruction was significantly lower than that of CT without iterative reconstruction in the 55-kg group (2.4 ± 0.9 vs. 3.3 ± 0.9,  = 0.04).

Conclusions: These results and current recommendations can be helpful for optimizing PET/CT diagnostic reference level (DRL) and reducing unnecessary PET/CT radiation exposure.
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http://dx.doi.org/10.1007/s13139-020-00654-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7560676PMC
October 2020

Effect of sex on aging-related decline of dopamine transporter in healthy subjects.

Ann Nucl Med 2021 Jan 14;35(1):76-82. Epub 2020 Oct 14.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.

Objective: Aging decreases dopamine transporter (DAT) availability of striatum both in humans and rodents. We aimed to investigate the relationship of DAT availabilities from ventral striatum, caudate nucleus, and putamen with aging in healthy subjects.

Methods: I-FP-CIT single photon emission computed tomography (SPECT) was performed in all subjects. Specific binding of I-FP-CIT regarding DAT was calculated using a volume-of-interest-based analysis of ventral striatum, caudate nucleus, putamen. The cerebellum was chosen as a reference region. Specific binding ratios (SBRs) were calculated as follows: SBR = (target- cerebellum)/cerebellum.

Results: A total of 166 healthy subjects (109 males and 57 females) were included in this study. SBRs of ventral striatum, caudate nucleus, and putamen were negatively correlated with age. In young males, SBRs of ventral striatum and putamen were not correlated with aging. However, SBRs of caudate nucleus showed the trend toward negative correlation with age in the young group. In old males, SBR of caudate nucleus was negatively correlated with age and SBR of ventral striatum showed a trend toward negative correlation with age. Slopes of regression lines were not significantly different according to age groups in ventral striatum, caudate nucleus, or putamen. SBRs of ventral striatum, caudate nucleus, and putamen were negatively correlated with age in young females, but not in old females. Interestingly, slopes of regression line were significantly different between young and old females in ventral striatum, caudate nucleus, and putamen.

Conclusions: We have shown that slopes of regression lines of DAT availabilities and age were significantly different between young and old subjects in females, not in males. Therefore, sex has an impact on aging-related decline of striatal DAT availability.
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http://dx.doi.org/10.1007/s12149-020-01538-8DOI Listing
January 2021

Association of Regional Bone Synthetic Activities of Vertebral Corners and Vertebral Bodies Quantified Using F-Fluoride Positron Emission Tomography with Bone Mineral Density on Dual Energy X-ray Absorptiometry in Patients with Ankylosing Spondylitis.

J Clin Med 2020 Aug 17;9(8). Epub 2020 Aug 17.

Biomedical Research Institute, Pusan National University Hospital, Busan 49241, Korea.

We investigated whether the bone-synthetic activities of vertebral bodies or vertebral corners quantified using F-fluoride positron emission tomography (PET) was associated with bone mineral density (BMD) at the corresponding lumbar vertebrae in ankylosing spondylitis (AS) at each vertebra level. We analyzed 48 lumbar vertebrae in 12 AS patients who underwent F-fluoride PET and dual energy X-ray absorptiometry (DXA). The mean standardized uptake values (SUVmean) of the vertebral body and corners from L1 to L4 were measured using the spatially separated region of interest (ROI). The L1-L4 BMDs were calculated based on the DXA ("conventional BMD"). The BMD of the internal vertebral bodies was measured by manually drawing ROIs to represent the trabecular BMD ("alternative BMD"). After adjusting the within-patient correlation, the F-fluoride SUVmean of the vertebral corners but not that of vertebral bodies was significantly related with the conventional BMD of the vertebra. Otherwise, the F-fluoride uptake of both the vertebral and vertebral bodies was significantly related with the alternative BMD. The bone-synthetic activities of the vertebral corners may be more closely related with BMD than those of the vertebral bodies, suggesting that the effects of regional bone metabolism at the vertebral corners and bodies on BMD differ in AS.
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http://dx.doi.org/10.3390/jcm9082656DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7465964PMC
August 2020

Development and Validation of a Risk Scoring System Derived from Meta-Analyses of Papillary Thyroid Cancer.

Endocrinol Metab (Seoul) 2020 06 24;35(2):435-442. Epub 2020 Jun 24.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Korea.

Background: The aim of this study was to develop a scoring system to stratify the risk of papillary thyroid cancer (PTC) and to select the proper management.

Methods: We performed a systematic search of MEDLINE and Embase. Data regarding patients' prognoses were obtained from the included studies. Odds ratios (ORs) with statistical significance were extracted from the publications. To generate a risk scoring system (RSS), ORs were summed (RSS1), and summed after natural-logarithmic transformation (RSS2). RSS1 and RSS2 were compared to the eighth edition of the American Joint Committee on Cancer (AJCC) staging system and the 2015 American Thyroid Association (ATA) guidelines for thyroid nodules and differentiated thyroid carcinoma.

Results: Five meta-analyses were eligible for inclusion in the study. Eight variables (sex, tumour size, extrathyroidal extension, BRAF mutation, TERT mutation, histologic subtype, lymph node metastasis, and distant metastasis) were included. RSS1 was the best of the analysed models.

Conclusion: We developed and validated a new RSS derived from previous meta-analyses for patients with PTC. This RSS seems to be superior to previously published systems.
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http://dx.doi.org/10.3803/EnM.2020.35.2.435DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7386116PMC
June 2020

Diagnostic Accuracy and Confidence of [18F] FDG PET/MRI in comparison with PET or MRI alone in Head and Neck Cancer.

Sci Rep 2020 06 11;10(1):9490. Epub 2020 Jun 11.

Department of Radiology, Seoul National University Hospital, 101, Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.

The usefulness of PET/MRI in head and neck malignancy has not been fully elucidated. The purpose of our study was to evaluate the diagnostic accuracy and confidence of PET/MRI in comparison with PET or MRI alone. This study included 73 consecutive patients who underwent [18F] FDG PET/MRI in head and neck under the suspicion of malignancy. A neuroradiologist and a nuclear medicine specialist reviewed MRI and PET images, respectively and independently, followed by a consensus review of PET/MRI one month later. For 134 lesions, accuracy and confidence were compared among PET, MRI, and PET/MRI. For lesion base, PET/MRI had a sensitivity of 85.7%, a specificity of 89.1%, a PPV of 89.6%, a negative predictive value of 85.1%, and an accuracy of 87.3%. AUCs of PET/MRI per lesion (0.926) and per patient (0.934) for diagnosing malignancy were higher than PET (0.847 and 0.747, respectively) or MRI (0.836 and 0.798, respectively) alone (P < 0.05). More than 80% of the cases (111/134) showed diagnostic concordance between PET and MRI. PPV of PET/MRI was higher in malignant concordant cases (93.2%, 55/59) than in discordant cases (62.5%, 5/8) (p = 0.040). Confident scoring rate in malignant concordant cases was higher on PET/MRI (96.6%, 57/59) than on MRI (76.3%, 45/59) (p = 0.003). In conclusion, compared with PET or MRI alone, PET/MRI presents better diagnostic performance in accuracy and confidence for diagnosis of malignancy. PET/MRI is useful in patients with head and neck cancer.
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http://dx.doi.org/10.1038/s41598-020-66506-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7289810PMC
June 2020

Comparison of Amyloid in Cerebrospinal Fluid, Brain Imaging, and Autopsy in a Case of Progressive Supranuclear Palsy.

Alzheimer Dis Assoc Disord 2020 Jul-Sep;34(3):275-277

Departments of Neurology.

Cerebrospinal fluid (CSF) amyloid-beta 1-42 (Aβ1-42) and amyloid positron emission tomography (PET) are the 2 main Alzheimer disease amyloid biomarkers that have been validated in neuropathologically confirmed Alzheimer disease cases. Although many studies have shown concordance of amyloid positivity or negativity between CSF Aβ1-42 and amyloid PET, several studies also reported discrepancies between these 2 Aβ biomarkers. We conducted a comparison of CSF Aβ1-42 level, amyloid PET, and autopsy findings in a case with progressive supranuclear palsy in which biomarker acquisition and postmortem pathologic examination were conducted almost at the same time. Our case with antemortem CSF Aβ1-42 (+)/amyloid PET (-) who was pathologically confirmed with Aβ pathology in the cerebral cortex may indicate CSF Aβ1-42 is more sensitive for assessing in vivo Aβ than amyloid PET.
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http://dx.doi.org/10.1097/WAD.0000000000000396DOI Listing
July 2021

Prognostic value of metabolic tumor volume and total lesion glycolysis in breast cancer: a meta-analysis.

Nucl Med Commun 2020 Aug;41(8):824-829

Centre for Epidemiology & Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, VIC, Australia.

Objectives: PET using F-fluorodeoxyglucose (FDG) has proven to be valuable in staging and monitoring of treatment response in breast cancer. We aimed to assess the prognostic value of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in patients with breast cancer.

Methods: A systematic search of MEDLINE and EMBASE was performed using the keywords of breast cancer, PET, and volume. Inclusion criteria were F-FDG PET used as an initial imaging tool; studies limited to patients with breast cancer who had not undergone any treatment before PET scans; and studies reporting survival data. Event-free survival (EFS) and overall survival (OS) were considered markers of outcome.

Results: Nine studies comprising 975 patients were included in this study. The pooled hazard ratio (HR) for adverse events was 33.73 (P < 0.00001; I = 0%) with MTV from primary tumor and 2.89 (P < 0.00001; I = 45%) with TLG from primary tumor, meaning that primary tumors with high volumetric parameters were associated with progression or recurrence. However, the combined HRs for EFS of MTV, and TLG, and those for OS of MTV from whole-body tumor were NS. The pooled HR for OS of TLG from whole-body tumor was 2.95 (P = 0.18; I = 71%).

Conclusion: Volumetric parameters from F-FDG PET are significant prognostic factors for outcome in patients with breast cancer. Patients with a high MTV or TLG from primary tumor have a higher risk of adverse events. Patients with a high TLG from whole-body tumor have a higher risk of deaths.
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http://dx.doi.org/10.1097/MNM.0000000000001227DOI Listing
August 2020

Effects of animal handling on striatal DAT availability in rats.

Ann Nucl Med 2020 Jul 18;34(7):496-501. Epub 2020 May 18.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, 179 Gudeok-ro, Seo-gu, Busan, 49241, Republic of Korea.

Objective: Positron emission tomography (PET) is a non-invasive technique measuring quantification of physiological and biochemical processes in the living organism. However, there are many considerations including anesthesia and fasting to acquire small animal imaging. We aimed to evaluate the effects of anesthesia and fasting of rats in dopamine transporter (DAT) imaging acquisition.

Methods: Male Sprague Dawley (SD) rats aged 7 weeks and weighing 180-260 g were used in this study. Rats were randomly divided by 4 groups. Group A was kept under anesthesia for 40 min and fasted over 12 h. Group B was only fasted over 12 h. Group C was only kept under anesthesia for 40 min. Group D was neither kept under anesthesia nor fasted over 12 h. PET scans were started at 40 min after F-FP-CIT injection and obtained for 20 min. Volumes-of-interest for striatum and extrastriatal area were used for F-FP-CIT PET analysis. Cerebellum was considered as a reference region. Specific binding ratio (SBR) was calculated as follows: [(uptake of target-uptake of cerebellum)]/(uptake of cerebellum).

Results: SBR without fasting and anesthesia (group D) was significantly lower than those of other groups (vs group A, p = 0.0004; vs group B, p = 0.0377; vs group C, p = 0.0134). However, SBRs of extrastriatal area (p = 0.5120) were not affected by fasting and anesthesia.

Conclusions: In conclusion, the SBR of striatum was increased after anesthesia by isoflurane and fasting. When designing an experiment using DAT imaging, the effects of isoflurane and fasting should be considered.
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http://dx.doi.org/10.1007/s12149-020-01476-5DOI Listing
July 2020

Sleep and Neuroimaging.

Nucl Med Mol Imaging 2020 Apr 15;54(2):98-104. Epub 2020 Apr 15.

1Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, 179 Gudeok-ro, Seo-gu, Busan, 49241 Republic of Korea.

We spend about one-third of our lives either sleeping or attempting to sleep. Therefore, the socioeconomic implications of sleep disorders may be higher than expected. However, the fundamental mechanisms and functions of sleep are not yet fully understood. Neuroimaging has been utilized to reveal the connectivity between sleep and the brain, which is associated with the physiology of sleep. Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging studies have become increasingly common in sleep research. Recently, significant progress has been made in understanding the physiology of sleep through neuroimaging and the use of various radiopharmaceuticals, as the sleep-wake cycle is regulated by multiple neurotransmitters, including dopamine, adenosine, glutamate, and others. In addition, the characteristics of rapid eye and non-rapid eye movement sleep have been investigated by measuring cerebral glucose metabolism. The physiology of sleep has been investigated using PET to study glymphatic function as a means to clear the amyloid burden. However, the basic mechanisms and functions of sleep are not yet fully understood. Further studies are needed to investigate the effects and consequences of chronic sleep deprivation, and the relevance of sleep to other diseases.
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http://dx.doi.org/10.1007/s13139-020-00636-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7198660PMC
April 2020

Lymphocyte-to-monocyte ratio prior to radioiodine ablation in low- and intermediate-risk, papillary thyroid cancer.

Endocrine 2020 11 5;70(2):364-371. Epub 2020 May 5.

Department of Nuclear Medicine, Pusan National University Yangsan Hospital, Yangsan, 50612, Republic of Korea.

Purpose: We aimed to investigate inflammation indices based on preablation hematological parameter of the lymphocyte-to-monocyte ratio (LMR) to predict the clinical outcome in papillary thyroid cancer (PTC) patients with low- and intermediate-risk stratification.

Methods: This retrospective study analyzed 772 patients with low- and intermediate-risk PTC who underwent total thyroidectomy followed by radioiodine therapy between July 2005 and July 2009 with a median of 10 years. Kaplan-Meier statistics were used to test differences in recurrence-free survival (RFS) between groups based on the optimal cutoff point of biomarkers identified using receiver operating characteristic curves.

Results: With an optimal cutoff point of 7.05, 215 patients (29.8%) were classified as having low LMR and 557 patients (71.2%) were classified as having high LMR. High LMR was significantly associated with a prolonged RFS (hazard ratio [HR]: 2.048, 95% confidence interval [CI]: 1.062-4.359, p = 0.001). Multivariate analysis showed that low LMR (HR = 2.035, 95% CI: 1.011-4.095, p = 0.012), tumor size over 2 cm (HR = 2.762, 95% CI: 1.303-5.852, p = 0.008), and high preablative simulated thyroglobulin level over 10 ng/ml (HR = 7.826, 95% CI: 2.353-26.033, p < 0.001) were independent prognostic markers for worse RFS in the enrolled PTC patients.

Conclusions: LMR at the time of radioiodine therapy has comparable predictor for the clinical outcome with both tumor size and preablative simulated thyroglobulin level in low- to intermediate-risk PTC patients.
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http://dx.doi.org/10.1007/s12020-020-02328-yDOI Listing
November 2020

A User-Friendly, Web-Based Integrative Tool (ESurv) for Survival Analysis: Development and Validation Study.

J Med Internet Res 2020 05 5;22(5):e16084. Epub 2020 May 5.

Department of Anatomy, School of Medicine, Pusan National University, Yangsan, Republic of Korea.

Background: Prognostic genes or gene signatures have been widely used to predict patient survival and aid in making decisions pertaining to therapeutic actions. Although some web-based survival analysis tools have been developed, they have several limitations.

Objective: Taking these limitations into account, we developed ESurv (Easy, Effective, and Excellent Survival analysis tool), a web-based tool that can perform advanced survival analyses using user-derived data or data from The Cancer Genome Atlas (TCGA). Users can conduct univariate analyses and grouped variable selections using multiomics data from TCGA.

Methods: We used R to code survival analyses based on multiomics data from TCGA. To perform these analyses, we excluded patients and genes that had insufficient information. Clinical variables were classified as 0 and 1 when there were two categories (for example, chemotherapy: no or yes), and dummy variables were used where features had 3 or more outcomes (for example, with respect to laterality: right, left, or bilateral).

Results: Through univariate analyses, ESurv can identify the prognostic significance for single genes using the survival curve (median or optimal cutoff), area under the curve (AUC) with C statistics, and receiver operating characteristics (ROC). Users can obtain prognostic variable signatures based on multiomics data from clinical variables or grouped variable selections (lasso, elastic net regularization, and network-regularized high-dimensional Cox-regression) and select the same outputs as above. In addition, users can create custom gene signatures for specific cancers using various genes of interest. One of the most important functions of ESurv is that users can perform all survival analyses using their own data.

Conclusions: Using advanced statistical techniques suitable for high-dimensional data, including genetic data, and integrated survival analysis, ESurv overcomes the limitations of previous web-based tools and will help biomedical researchers easily perform complex survival analyses.
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http://dx.doi.org/10.2196/16084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7238095PMC
May 2020

Prediction of Response to Tumor Necrosis Value-α Blocker Is Suggested by F-NaF SUV But Not by Quantitative Pharmacokinetic Analysis in Patients With Ankylosing Spondylitis.

AJR Am J Roentgenol 2020 06 14;214(6):1352-1358. Epub 2020 Apr 14.

Department of Nuclear Medicine, Pusan National University Yangsan Hospital, Yangsan 50612, Republic of Korea.

We aimed to evaluate the pharmacokinetics and maximum standardized uptake value (SUV) of F-NaF PET/CT for assessment of disease activity and prediction of response in patients with ankylosing spondylitis (AS). Twenty-seven patients (age, interquartile range, 30.25-49.75 years) with AS who were receiving a tumor necrosis factor-α (TNF-α) blocker were included. All patients underwent dynamic PET of the pelvis followed by whole-body PET/CT. Quantitative analysis of kinetic data of the sacroiliac joints (SIJs) was performed, and the SUV of the SIJs and SUV of the spine were calculated. Clinical indexes related to AS disease activity (serum C-reactive protein level, Bath ankylosing spondylitis disease activity index [ BASDAI], and Bath ankylosing spondylitis functional index) were evaluated. Clinical response was defined as an improvement from the initial BASDAI score of 50% or more (BASDAI 50) within 2 years after baseline F-NaF PET/CT. The BASDAI score at F-NaF PET/CT was significantly different between the responders and nonresponders: F-NaF uptake at the spine was significantly higher in the responders than in the nonresponders. Only SUV of the spine had a significant positive correlation with BASDAI score at PET/CT ( = 0.38, = 0.048). The BASDAI score at PET/CT (odds ratio [OR], 35.32; 95% CI, 2.09-57.84; = 0.014) and SUV of the spine (OR, 14.69; 95% CI, 0.79-27.27; = 0.027) were significantly associated with BASDAI 50 response prediction. The results of our study suggest that the SUV of the spine on whole-body F-NaF PET/CT is a reliable and noninvasive biomarker for predicting therapeutic response to TNF-α blocker and shows better performance for predicting response than quantitative pharmacokinetic parameters. Fluorine-18-labeled NaF PET/CT showed axial bone lesions with bone formation and can be used as a monitoring tool in patients with AS receiving anti-TNF-α drugs. However, these results need to be validated in a larger cohort.
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http://dx.doi.org/10.2214/AJR.19.22352DOI Listing
June 2020

Evaluation of the diagnostic performance of F-NaF positron emission tomography/computed tomography in patients with suspected ankylosing spondylitis according to the Assessment of SpondyloArthritis International Society criteria.

Spine J 2020 09 19;20(9):1471-1479. Epub 2020 Mar 19.

Department of Orthopaedic Surgery, Biomedical Research Institute, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Republic of Korea. Electronic address:

Background Context: Positron emission tomography (PET) is a potential imaging technique for the diagnosis of AS. The visualization of physiological change makes PET potentially suitable for early detection of inflammatory processes, even before anatomical changes occur. Thus, PET might provide specificity via the use of receptor targeting tracers and allows quantification of disease activity in order to accurately monitor therapeutic effects.

Purpose: To examine fluorine-18 sodium fluoride (F-NaF) PET/computed tomography (PET/CT) findings in patients with inflammatory low back pain and evaluate the utility of this modality in the diagnosis of ankylosing spondylitis (AS) according to the Assessment of SpondyloArthritis International Society (ASAS) criteria.

Study Design: Retrospective cohort study.

Patients Sample: Sixty-eight patients who underwent F-NaF PET/CT imaging between April 2015 and April 2017 for evaluation of inflammatory low back pain.

Outcome Measures: We defined AS-positive lesions on PET/CT as symmetric sacroiliac joint uptake that suggests sacroiliitis, syndesmophytes on the spine, and enthesopathy at any site.

Methods: All patients were evaluated using the ASAS criteria and assigned to either the AS or the control group. The diagnostic criteria of AS on PET/CT images were defined as F-NaF PET/CT images with at least one of AS-positive findings.

Results: The diagnostic rate of AS was 72.1% among the 68 patients according to the ASAS criteria. The baseline characteristics between the two groups differed significantly in terms of serum C-reactive protein levels and the presence of human leucocyte antigen-B27. Compared to the control group, in the AS group, 39 patients (79.5%) exhibited typical F-NaF PET/CT-positive findings, such as enthesopathy (65.3%, p=.003), syndesmophytes (61.2%, p=.006) and symmetric sacroiliitis (67.3%, p=.001). PET-positive findings had significantly higher area under the curve values than did single F-NaF PET/CT- positive findings, and they had the best performance for concordant diagnosis according to the ASAS criteria.

Conclusions: F-NaF PET/CT yielded significantly different findings between the two groups according to the ASAS criteria and is useful for diagnosing AS.
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http://dx.doi.org/10.1016/j.spinee.2020.03.011DOI Listing
September 2020

Author Correction: Cerebral glucose metabolism and Cerebral blood flow in thyroid dysfunction: An Activation Likelihood Estimation Meta-analysis.

Sci Rep 2020 Mar 19;10(1):5369. Epub 2020 Mar 19.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41598-020-62219-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7081320PMC
March 2020

Comparison of Diagnostic Performances Between Cerebrospinal Fluid Biomarkers and Amyloid PET in a Clinical Setting.

J Alzheimers Dis 2020 ;74(2):473-490

Department of Neurology, Pusan National University Hospital, Pusan National University School of Medicine and Medical Research Institute, Busan, Republic of Korea.

The diagnostic performances of cerebrospinal fluid (CSF) biomarkers and amyloid positron emission tomography (PET) were compared by examining the association and concordance or discordance between CSF Aβ1-42 and amyloid PET, after determining our own cut-off values for CSF Alzheimer's disease (AD) biomarkers. Furthermore, we evaluated the ability of CSF biomarkers and amyloid PET to predict clinical progression. CSF Aβ1-42, t-tau, and p-tau levels were analyzed in 203 individuals [27 normal controls, 38 mild cognitive impairment (MCI), 62 AD dementia, and 76 patients with other neurodegenerative diseases] consecutively recruited from two dementia clinics. We used both visual and standardized uptake value ratio (SUVR)-based amyloid PET assessments for analyses. The association of CSF biomarkers with amyloid PET SUVR, hippocampal atrophy, and cognitive function were investigated by linear regression analysis, and the risk of conversion from MCI to AD dementia was assessed using a Cox proportional hazards model. CSF p-tau/Aβ1-42 and t-tau/Aβ1-42 exhibited the best diagnostic accuracies among the CSF AD biomarkers examined. Correlations were observed between CSF biomarkers and global SUVR, hippocampal volume, and cognitive function. Overall concordance and discordance between CSF Aβ1-42 and amyloid PET was 77% and 23%, respectively. Baseline positive CSF Aβ1-42 for MCI demonstrated a 5.6-fold greater conversion risk than negative CSF Aβ1-42 .  However, amyloid PET findings failed to exhibit significant prognostic value. Therefore, despite presence of a significant correlation between the CSF Aβ1-42 level and SUVR of amyloid PET, and a relevant concordance between CSF Aβ1-42 and amyloid PET, baseline CSF Aβ1-42 better predicted AD conversion.
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http://dx.doi.org/10.3233/JAD-191109DOI Listing
May 2021

How Can We Predict a Successful Outcome after Varicocelectomy in Painful Varicocele Patients? An Updated Meta-Analysis.

World J Mens Health 2021 Oct 3;39(4):645-653. Epub 2019 Dec 3.

Department of Urology, Pusan National University School of Medicine, Busan, Korea.

Purpose: This study evaluated the relationships of varicocele characteristics and surgical methods with the pain resolution rate post-varicocelectomy.

Materials And Methods: A literature search was conducted using PubMed (MEDLINE) and Embase (1980 to December 2018). The keywords used for the search were "varicocele," "varicocelectomy OR ligation OR repair," and "pain OR painful." Two authors independently reviewed the titles and abstracts of the retrieved articles. Studies were evaluated for eligibility, and those that fulfilled all of the inclusion criteria and none of the exclusion criteria were selected for full-text review.

Results: Fourteen studies were included in the analysis. There were no significant differences in the postoperative pain resolution rate with respect to varicocele grades I, II, and III. The resolution rate was significantly higher for dull pain than for dragging and sharp pain (odds ratio [OR], 5.73; 95% confidence interval [CI], 1.78-18.41; p=0.003 and OR, 8.72; 95% CI, 2.91-26.08; p=0.0001, respectively). In terms of the surgical approach, subinguinal ligation was significantly more effective in terms of pain resolution than high ligation (OR, 2.73; 95% CI, 1.54-4.85; p=0.0006). Microsurgical varicocelectomy showed a significantly higher likelihood of pain resolution than laparoscopic varicocelectomy (OR, 7.12; 95% CI, 3.78-13.44; p<0.0001).

Conclusions: Patients with varicocele complaining of dull pain preoperatively had a higher likelihood of postoperative pain resolution than those complaining of dragging or sharp pain. Furthermore, subinguinal ligation was more effective for pain resolution than high ligation, and microsurgical varicocelectomy showed better surgical outcomes than laparoscopic varicocelectomy.
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http://dx.doi.org/10.5534/wjmh.190112DOI Listing
October 2021

Cerebral glucose metabolism and Cerebral blood flow in thyroid dysfunction: An Activation Likelihood Estimation Meta-analysis.

Sci Rep 2020 Jan 28;10(1):1335. Epub 2020 Jan 28.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.

Thyroid dysfunction is frequently associated with functional disturbances of the brain. We performed a meta-analysis of previous positron emission tomography and single-photon emission computed tomography studies using a coordinate-based technique of activation-likelihood estimation (ALE) to investigate the potential background of neuropsychiatric complications in patients with hypo- and hyperthyroidism. We performed a systematic search of MEDLINE and EMBASE for English-language publications using the keywords of "positron emission tomography", "single-photon emission computed tomography", and "thyroid". The software GingerALE ver 2.3.6 was used to transform all reported coordinates into stereotactic Montreal Neurological Institute space. A threshold of uncorrected p < 0.001 (minimum volume of 200 mm) was applied to the resulting ALE map using cerebral metabolic rate of glucose (CMRglu), and cerebral blood flow (CBF). Six studies were eligible for inclusion in the study; 4 studies of cerebral metabolic rate of CMRglu, and 2 studies of CBF. In hypothyroidism, significant decreases in CMRglu were identified in 3 clusters including left anterior cingulate, right inferior occipital gyrus, and right cuneus. In hyperthyroidism, a significant decrease in CMRglu was identified in right superior frontal gyrus. In hypothyroidism, a significant decrease in CBF was observed in left postcentral gyrus. In conclusion, several brain regions showed altered CMRglu and CBF in patients with thyroid dysfunction compared with euthyroid controls. These findings might account for underlying mechanisms of thyroid hormones on psychological and physiological effects on brain.
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http://dx.doi.org/10.1038/s41598-020-58255-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6987231PMC
January 2020

Prevalence of attention deficit hyperactivity disorder symptoms in narcolepsy: a systematic review.

Sleep Med 2020 01 3;65:84-88. Epub 2019 Aug 3.

Department of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea. Electronic address:

Objective: Narcolepsy is characterized by excessive daytime sleepiness and cataplexy. Attention deficit hyperactivity disorder (ADHD) is characterized by hyperactivity, inattention, and impulsivity. However, despite their differences, both narcolepsy and ADHD share the symptoms of sleep disturbance and excessive daytime sleepiness. Recent studies have suggested a link between the two disorders. The objective of systematic review was to assess the prevalence of ADHD symptoms in narcolepsy.

Methods: We performed a systematic search of MEDLINE (inception to December 2018) and EMBASE (inception to December 2018) for English publications of human studies using the keywords "narcolepsy" and "ADHD".

Results: Five studies examining a total of 328 patients met the eligibility criteria for this study examining the prevalence of ADHD symptoms in narcolepsy. The pooled prevalence of ADHD symptoms in narcolepsy was 33.0%. Two studies using the international classification of sleep disorders, second edition (ICSD-2) observed a pooled prevalence of ADHD symptoms in narcolepsy of 25.0%, while two other studies that relied on the ICSD-3 criteria observed a pooled prevalence of ADHD symptoms in narcolepsy of 36.4%.

Conclusions: The prevalence of ADHD symptoms was >30%, making it an important comorbidity of narcolepsy. Future studies should be performed to better assess the relationship between ADHD and narcolepsy.
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http://dx.doi.org/10.1016/j.sleep.2019.07.022DOI Listing
January 2020

The feasibility of quantitative parameters of lymphoscintigraphy without significant dermal backflow for the evaluation of lymphedema in post-operative patients with breast cancer.

Eur J Nucl Med Mol Imaging 2020 05 16;47(5):1094-1102. Epub 2019 Nov 16.

Department of Rehabilitation Medicine, Pusan National University School of Medicine and Biomedical Research Institute, Pusan National University Hospital, Gudeok-Ro Seo-Gu, Busan, 602-739, South Korea.

Purpose: We aimed to evaluate the potential role of quantitative methods associated with lymphoscintigraphy for the assessment of severity of lymphedema post-operatively in patients with breast cancer who did not show definite dermal backflow activity on the lymphoscintigraphy.

Methods: We evaluated 47 lymphoscintigraphies without dermal backflow in patients with lymphedema who received a mastectomy and axillary dissection or sentinel lymph node dissection for invasive ductal carcinoma of the breast. The quantitative asymmetry indices (QAIs) of both arms were calculated for each axilla, upper arm, forearm, and the whole arm. The QAI was defined as the radiopharmaceutical uptake ratio of the affected side to the unaffected side. Arm circumference was measured at four locations per arm to identify the maximal circumference difference (MCD) between affected and unaffected sides.

Results: The total and forearm QAIs of each side arm were significantly higher in the group with above moderate stage lymphedema compared with the mild stage group. Previous radiotherapy also had a significant effect on radiotracer retention expressed as QAI. The MCD was significantly correlated with QAI values of the forearm and the whole arm. The QAI of axillary areas was not significantly correlated with circumferential measurements of the arm.

Conclusions: The QAIs have significant value for the diagnosis and severity of lymphedema and may therefore potentially be used as an objective tool for the assessment of lymphedema.
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http://dx.doi.org/10.1007/s00259-019-04576-1DOI Listing
May 2020
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