Nagara Tamaki - Academia.edu (original) (raw)

Papers by Nagara Tamaki

IEEE Nuclear Science Symposium Conference Record, 2005

OSEM is a standard for image reconstruction in positron emission tomography (PET). However, OSEM ... more OSEM is a standard for image reconstruction in positron emission tomography (PET). However, OSEM has not been compared with filtered back projection (FBP) for the quantification of myocardial blood flow (MBF) with 13N-ammonia (NH3) and 82Rb PET. 12 subjects with <5% likelihood of CAD had rest and stress (dipyridamole) dynamic PET with NH3 and Rb. Arterial blood and myocardial polar-map

Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology, Jan 14, 2017

FDG PET/CT plays a significant role in the diagnosis of inflammatory heart diseases and cardiac t... more FDG PET/CT plays a significant role in the diagnosis of inflammatory heart diseases and cardiac tumors. We attempted to determine the optimal FDG uptake threshold for volume-based analyses and to evaluate the relationship between the myocardial physiological uptake volume in FDG PET and several clinical factors. A total of 190 patients were retrospectively analyzed. The cardiac metabolic volume (CMV) was defined as a volume within the boundary determined by a threshold (SUVmean of blood pool × 1.5). The SUVmean of the blood pool measured in the descending aorta (DA) (r = 0.86, intraclass correlation coefficient [ICC] = 0.93, P < 0.0001) and that in the left ventricle (LV) cavity (r = 0.87, ICC = 0.90, P < 0.0001) showed high inter-operator reproducibility. However, the SUVmean in the LV cavity showed a significant correlation with the CMV (P = 0.0002, r = 0.26). The CMV in the patients who fasted < 18 hours were significantly higher (49.7 ± 73.2 vs. 18.0 ± 53.8 mL, P = ...

Springer eBooks, 2016

Tumor hypoxia is an important object for imaging because hypoxia is associated with tumor aggress... more Tumor hypoxia is an important object for imaging because hypoxia is associated with tumor aggressiveness and resistance to radiation therapy. Here, 18 Ffluoromisonidazole (FMISO) has been used for many years as the most commonly employed hypoxia imaging tracer. Unlike F-18 fluorodeoxyglucose (FDG), FMISO does not accumulate in normal brain tissue making it able to provide images of hypoxic brain tumors with high contrast. Clinical evidence has suggested that FMISO PET can predict patient prognosis and treatment response. Among gliomas of various grades (WHO 2007), it has been known that grade IV glioblastoma resides under severe hypoxia and is a cause of development of necrosis in the tumor. For this study we tested whether FMISO can distinguish the oxygen condition of glioblastomas and lower-grade gliomas. Twenty-three glioma patients underwent FMISO PET for the study. All the glioblastoma patients (N ¼ 14) showed high FMISO uptakes in the tumor, whereas none of the other patients (i.e., gliomas of grade III or lower, N ¼ 9) did, demonstrated by both qualitative and quantitative assessments. The data suggest that FMISO PET may be a useful tool to distinguish glioblastomas from lower-grade gliomas. Our results, however, were slightly different from previous investigations reporting that some lowergrade gliomas (e.g., grade III) showed positive FMISO uptake. Many of these acquired the FMISO PET images 2 h after the FMISO injection, while for the study here we waited 4 h to be able to collect hypoxia-specific signals rather than perfusion signals as FMISO clearance from plasma is slow due to its lipophilic nature. No optimum uptake time for FMISO has been established, and we directly compared the 2-h vs. the 4-h images with the same patients (N ¼ 17). At 2 h, the gray matter had significantly higher standardized uptake value (SUV) than the white matter, possibly due to different degrees of perfusion but not due to hypoxia. At 4 h, there were no differences between gray and white matter without any significant increase in the noise level measured by the coefficient of variation between the 2-h and the 4-h images. At 2 h, 6/8 (75 %) of glioblastoma patients

PLOS ONE, Dec 9, 2016

Background Bevacizumab (BEV), a humanized monoclonal antibody, become a currently important chemo... more Background Bevacizumab (BEV), a humanized monoclonal antibody, become a currently important chemotherapeutic option for the patients with recurrent glioma. The aim of this retrospective study is to investigate whether 18 F-Fluoromisonidazole (FMISO) PET have the potential to detect BEV-resistant gliomas in the early-stage. Methods We reviewed the FMISO PET and MRI appearances before and 3 to 4 courses after BEV treatment on 18 recurrent glioma patients. FMISO accumulation was assessed by visual inspection and semi-quantitative values which were tumor-to-normal (T/N) ratio and hypoxic volume. MRI responses were evaluated based on RANO (Response Assessment in Neuro-Oncology) criteria. The prognostic analysis was performed in relation to the response assessment by FMISO PET and MRI using overall survival (OS) after BEV application. Results After BEV application, MRI revealed partial response in 14 of 18 patients (78%), of which 9 patients also demonstrated decreased FMISO accumulation. These 9 patients (50%) were classified as "MRI-FMISO double responder". As for the other 5 patients (28%), FMISO accumulation volumes increased or remained stable after BEV treatment although partial responses were achieved on MRI. Therefore, these cases were classified as "MRI-only responder". The remaining 4 patients (22%) did not show treatment response on FMISO PET or MRI ("non-responder"). MRI-FMISO double responders showed significantly longer OS than that in other groups (median 12.4 vs 5.7 months; P < 0.001), whereas there were no overall survival difference between MRI-only responders and non-responders

Japanese Journal of Radiology

Positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) has been commonly used in m... more Positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) has been commonly used in many oncological areas. High-resolution PET permits a three-dimensional analysis of FDG distributions on various lesions in vivo, which can be applied for tissue characterization, risk analysis, and treatment monitoring after chemoradiotherapy and immunotherapy. Metabolic changes can be assessed using the tumor absolute FDG uptake as standardized uptake value (SUV) and metabolic tumor volume (MTV). In addition, tumor heterogeneity assessment can potentially estimate tumor aggressiveness and resistance to chemoradiotherapy. Attempts have been made to quantify intratumoral heterogeneity using radiomics. Recent reports have indicated the clinical feasibility of a dynamic FDG PET-computed tomography (CT) in pilot cohort studies of oncological cases. Dynamic imaging permits the assessment of temporal changes in FDG uptake after administration, which is particularly useful for differentiating p...

Cancer Science, 2021

This is an open access article under the terms of the Creat ive Commo ns Attri bution-NonCo mmerc... more This is an open access article under the terms of the Creat ive Commo ns Attri bution-NonCo mmercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Neuro-Oncology Advances, 2020

Background: Although 11C-Methionine (MET) PET has widely used, 11C-MET tracer has not been approv... more Background: Although 11C-Methionine (MET) PET has widely used, 11C-MET tracer has not been approved in Japan. We conducted multi-center prospective clinical trials using MET for drug approval in diagnosis of brain tumors[Methods] Two trials using 11C-MET PET were performed in Hokkaido University, Osaka University and Fukushima Medical University; 1) Diagnostic accuracy in differentiating tumor recurrence from radiation injury after radiotherapy in brain tumors, 2) The diagnostic efficacy in newly-diagnosed gliomas. 1) The patients with suspected brain tumor recurrence underwent MET and 18F-Fluorodeoxyglucose (FDG) PET. When the target lesion showed MET and/or FDG uptake, the patients underwent target resection for pathological confirmation. Positive prediction values of each tracer uptake were assessed as primary outcome measure, and the sensitivities and specificities of each PET exams were also assessed. 2) The patients with suspected gliomas underwent MET PET. Tissue samplings we...

Cancers, 2021

Positron emission tomography (PET) has unique characteristics for quantitative assessment of tumo... more Positron emission tomography (PET) has unique characteristics for quantitative assessment of tumour biology in vivo. Accumulation of F-18 fluorodeoxyglucose (FDG) may reflect tumour characteristics based on its metabolic activity. Quantitative assessment of FDG uptake can often be applied for treatment monitoring after chemotherapy or chemoradiotherapy. Numerous studies indicated biochemical change assessed by FDG PET as a more sensitive marker than morphological change estimated by CT or MRI. In addition, those with complete metabolic response after therapy may show better disease-free survival and overall survival than those with other responses. Assessment of metabolic change may be performed using absolute FDG uptake in the tumour (standardized uptake value: SUV). In addition, volumetric parameters such as metabolic tumour volume (MTV) have been introduced for quantitative assessment of FDG uptake in tumour. More recently, radiomics approaches that focus on image-based precision...

Journal of Nuclear Medicine, 2017

EJNMMI Research, 2017

Background: The quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR) are... more Background: The quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR) are useful approaches for evaluating the functional severity of coronary artery disease (CAD). 15 O-water positron emission tomography (PET) is considered the gold standard method for MBF quantification. However, MBF measurements in 15 O-water PET with three-dimensional (3D) data acquisition, attenuation correction using computed tomography (CT), and time of flight have not been investigated in detail or validated. We conducted this study to evaluate the diagnostic potential of MBF measurements using PET/CT for a comparison of a control group and patients suspected of having CAD. Results: Twenty-four patients with known or suspected CAD and eight age-matched healthy volunteers underwent rest and pharmacological stress perfusion studies with 15 O-water PET/CT. The whole and three regional (left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) territory) MBF values were estimated. The CFR was computed as the ratio of the MBF during adenosine triphosphate-induced stress to the MBF at rest. The inter-observer variability was assessed by two independent observers. PET/CT using a 15 O-water dose of 500 MBq and 3D data acquisition showed good image quality. A strong inter-observer correlation was detected in both the whole MBF analysis and the regional analysis with high intra-class correlation coefficients (r > 0.90, p < 0.001). Regional MBF at rest (LAD, 0.82 ± 0.15 ml/min/g; LCX, 0.83 ± 0.17 ml/min/g; RCA, 0.71 ± 0.20 ml/min/g; p = 0.74), MBF at stress (LAD, 3.77 ± 1.00 ml/min/g; LCX, 3.56 ± 1.01 ml/min/g; RCA, 3.27 ± 1.04 ml/min/g; p = 0.62), and CFR (LAD, 4.64 ± 0.90; LCX, 4.30 ± 0.64; RCA, 4.64 ± 0.96; p = 0.66) of the healthy volunteers showed no significant difference among the three regions. The global CFR of the patients was significantly lower than that of the volunteers (2.75 ± 0.81 vs. 4.54 ± 0.66, p = 0.0002). The regional analysis of the patients demonstrated that the CFR tended to be lower in the stenotic region compared to the non-stenotic region (2.43 ± 0.81 vs. 2.95 ± 0.92, p = 0.052). Conclusions: 15 O-water PET/CT with 3D data acquisition can be reliably used for the quantification of functional MBF and CFR in CAD patients.

BMC cancer, Jan 2, 2016

Volume-based parameters, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), ... more Volume-based parameters, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), on F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) are useful for predicting treatment response in nonsmall cell lung cancer (NSCLC). We aimed to examine intra- and inter-operator reproducibility to measure the MTV and TLG, and to estimate their dependency on the uptake time. Fifty NSCLC patients underwent preoperative FDG-PET. After an injection of FDG, the whole body was scanned twice: at the early phase (61.4 ± 2.8 min) and delayed phase (117.7 ± 1.6 min). Two operators independently defined the tumor boundary using three different delineation methods: (1) the absolute SUV threshold method (MTVp and TLGp; p = 2.0, 2.5, 3.0, 3.5), (2) the fixed% SUVmax threshold method (MTVq% and TLGq%; q = 35, 40, 45), and (3) the adaptive region-growing method (MTVARG and TLGARG). Parameters were compared between operators and between phases. Both the intra- and inter-operator reprod...

EJNMMI Research, 2017

Background: We aimed to assess the positivity, distribution, quantitative degree of vessel inflam... more Background: We aimed to assess the positivity, distribution, quantitative degree of vessel inflammation, and clinical characteristics of IgG4-related aortitis/periarteritis and periarteritis (IgG4-aortitis), and to examine the difference in these characteristics between cases with and without IgG4-aortitis, using fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) co-registered with contrast-enhanced CT (CECT). We retrospectively evaluated 37 patients with IgG4-related disease (IgG4-RD) who underwent both FDG-PET/CT and CECT. The arterial SUVmax and its value normalized to the background venous blood pool (BP)-the targetto-background ratio (TBR) in the entire aorta and the major first branches-were measured. Active vascular inflammation was considered in cases with a higher FDG uptake than BP and a thickened arterial wall (>2 mm). Results: Fifteen (41%) patients exhibited IgG4-aortitis. Most patients (80%) showed multiple region involvement. The entire aorta, including the major first branches, were involved, typically showing a thickened wall and high FDG uptakes. The most common site was the iliac arteries (35%), followed by the infrarenal abdominal aorta (33%), thoracic aorta (8%), first branches of the thoracic aorta (8%), suprarenal abdominal aorta (6%), and the first branches of the abdominal aorta (5%). The IgG4-aortitis-positive vessel regions were thickened, with an average maximal wall thickness of 6.3 ± 2.9 mm. The SUVmax and TBR values were significantly higher in the IgG4-aortitispositive regions (median 3.7 [1.6-5.5] and 2.1 [1.4-3.7], respectively) than in the IgG4-aortitis-negative regions (median 2.1 [1.2-3.7] and 1.3 [0.9-2.3], respectively; p < 0.0001). The IgG4-aortitis-positive group patients were older (69.5 ± 6.0 vs. 63.3 ± 12.6 years, respectively) and had a higher male predominance (80 vs. 55%, respectively) than the negative group, although the differences were not significant (p = 0.17 and p = 0.06, respectively). Conclusions: We investigated the image characteristics of IgG4-aortitis. The entire aorta and major branches can be involved with more than 2-fold higher FDG uptake than the venous background pool, and with wall thickening. The most common involved site is the iliac arteries, followed by the infrarenal abdominal aorta.

BMC cancer, Jan 15, 2016

Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a benign lymphoid proliferation... more Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a benign lymphoid proliferation or malignant lymphoma in patients who have been treated with MTX. MTX withdrawal and observation for a short period should be considered in the initial management of patients who develop LPD while on MTX therapy. Here we evaluated the diagnostic accuracy and predictive value of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) for MTX-LPD. We retrospectively investigated the cases of 15 patients clinically suspected of having MTX-LPD. A total of 324 anatomic regions (207 nodal and 117 extranodal regions) were assessed by (18)F-FDG PET/CT and by multi-detector row CT (MDCT). Each anatomic region was classified as either malignant or benign. The uptake of (18)F-FDG was assessed semi-quantitatively with the standardized uptake value maximum (SUVmax), the whole-body metabolic tumor volume (WBMTV), and the whole-body total lesion glycolysis (WBTLG) ...

Molecular Imaging for Integrated Medical Therapy and Drug Development, 2010

Objective: Intensity-modulated radiation therapy, an advanced mode of highprecision radiotherapy ... more Objective: Intensity-modulated radiation therapy, an advanced mode of highprecision radiotherapy developed to deliver precise radiation doses to specific areas within a tumor, has become popular in the clinical situation. With this modality, it has become particularly important in the clinical situation to estimate accurate cell activity with positron emission tomography (PET) scanner. We developed a new PET scanner with a semiconductor detector. Phantom images and [18F] fluorodeoxyglucose ([18F] FDG)-PET images of patients were measured to evaluate this new scanner's capacity to identify intratumoral inhomogeneous cell activity. Methods: The semiconductor PET scanner uses CdTe detectors. A cold spot phantom study was performed with 6-mm-diameter cold sphenoid defects. An "H"-shaped phantom, a dual-cylinder phantom, was also studied. These phantoms were surrounded with water. The phantom images and FDG-PET images of eight patients suffering with nasopharyngeal cancer were compared with images from a conventional BGO PET scanner (Siemens HR+). Profile curves of the phantom were measured in the phantom study. Contrast was defined as the peak-to-valley ratio. Intratumoral inhomogeneity and tumor edge sharpness were evaluated on the images of the patients. Results: The contrast obtained with the semiconductor PET scanner (1.53) was 28% higher than that obtained with the HR+ (1.20) for the 6-mm-diameter cold sphenoid phantom. The contrast obtained with the semiconductor PET scanner (1.43) was 27% higher than that obtained with the HR+ (1.13) for the dual-cylinder phantom. Similarly, the 2-mm cold region between 1-mm hot rods in the "H"-shaped phantom was identified only by the new PET scanner and not by the HR+. The new PET scanner identified intratumoral inhomogeneity in more detail than the HR+ in six of the eight patients. The tumor edge was sharper PET with Semiconductor Detector for Head and Neck Cancer 43 on the images obtained with the new PET scanner than on those obtained with the HR+. Conclusion: The new PET scanner has the potential for better identification of intratumoral inhomogeneous cell activity, with high spatial resolution and contrast.

Neurologia medico-chirurgica, 2012

Crossed cerebellar diaschisis (CCD) often occurs after ischemic or hemorrhagic stroke that damage... more Crossed cerebellar diaschisis (CCD) often occurs after ischemic or hemorrhagic stroke that damages the cortico-ponto-cerebellar pathway. However, CCD due to cerebral hyperperfusion following cerebrovascular reconstruction is rare. A 61-year-old woman presented with transient CCD due to cerebral hyperperfusion following bypass surgery for adult moyamoya disease. She developed transient weakness of the right extremities and was diagnosed with moyamoya disease. First, she underwent superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis with indirect synangiosis on the left. Postoperative course was uneventful. Subsequently, she underwent STA-MCA anastomosis with indirect synangiosis on the right. She complained of mild headache on the right, and single photon emission computed tomography (SPECT) performed on the 7th postoperative day demonstrated hyperperfusion in the right frontal and temporal lobes associated with hypoperfusion in the left cerebellum. Magnetic resonance (MR) imaging demonstrated no new lesions and MR angiography showed patent STA-MCA bypass. Subsequent SPECT showed disappearance of both hyperperfusion and CCD. This case strongly suggests that cerebral hyperperfusion after bypass surgery for moyamoya disease may cause transient CCD. Although the clinical significance is still obscure, this phenomenon indicates the cortico-ponto-cerebellar pathway is interrupted due to hyperperfusion, suggesting the development of hyperperfusion syndrome. Careful observation of cerebral hemodynamics after bypass surgery is warranted to avoid hyperperfusion-related complications.

Acta radiologica open, 2015

A 55-year-old woman underwent radiosurgery for a left cerebral hemisphere arteriovenous malformat... more A 55-year-old woman underwent radiosurgery for a left cerebral hemisphere arteriovenous malformation (AVM) and developed radiation-induced necrosis causing a massive edema in the surrounding brain tissues. Despite various therapies, the edema expanded to the ipsilateral hemisphere and induced neurological symptoms. The radiation-induced necrotic lesion was surgically removed 4 years after radiosurgery. While the preoperative FDG PET revealed severe hypometabolism in the left cerebrum, the necrotomy significantly ameliorated the brain edema, glucose metabolism (postoperative FDG PET), and symptoms. This case indicates that radiation necrosis-induced neurological deficits may be associated with brain edema and hypometabolism, which could be reversed by appropriate necrotomy.

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, Jan 4, 2015

The red nucleus (RN) is a pair of small gray matter structures located in the midbrain and involv... more The red nucleus (RN) is a pair of small gray matter structures located in the midbrain and involved in muscle movement and cognitive functions. This retrospective study aimed to investigate the metabolism of human RN and its correlation to other brain regions. We developed a high-resolution semiconductor PET system to image small brain structures. Twenty patients without neurological disorders underwent whole brain scanning after injection of 400 MBq F-18 fluorodeoxyglucose (FDG). The individual brain (18)F-FDG-PET images were spatially normalized to generate a surface projection map using a 3-dimensional stereotactic surface projection (3D-SSP) technique. The correlation between the RN and each voxel on the cerebral and cerebellar cortices was estimated with Pearson's product-moment correlation analysis. Both right and left RNs were visualized with higher uptake than that in the background midbrain. The maximum standardized uptake value (SUVmax) values of RN were 7.64±1.92; the...

World neurosurgery, 2013

Headache is one of the major clinical presentations in pediatric Moyamoya disease. However, the c... more Headache is one of the major clinical presentations in pediatric Moyamoya disease. However, the clinical features and underlying mechanisms are not fully understood. This study aimed to clarify the clinical feature of headache in pediatric Moyamoya disease and the effect of surgical revascularization. This study included 29 pediatric patients who underwent superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect bypass for Moyamoya disease. Their medical records were precisely evaluated to identify the clinical features of their headache. The findings on magnetic resonance imaging, positron emission tomography, and single-photon emission computed tomography also were analyzed. Preoperative headache was documented in 11 (38%) of 29 patients. The majority of them complained of severe headache in the frontal or temporal region in the morning. Headache was significantly related to more advanced disease stage and to the decreases in cerebral blood flow and...

Nuclear medicine communications, 2011

Cerebral blood flow (CBF) estimation with C15O2 PET usually assumes a single tissue compartment m... more Cerebral blood flow (CBF) estimation with C15O2 PET usually assumes a single tissue compartment model and a fixed brain-blood partition coefficient of water. However, the partition coefficient may change in pathological conditions. The purpose of this study was to investigate the changes in the partition coefficient of water in pathological regions and its effect on regional CBF assessment. The study protocol included 22 patients with occlusive cerebrovascular disease to compare the partition coefficients among three regions (infarction area, noninfarct hypoperfusion area, and contralateral area) in the pathological brain (analysis A), and to compare the CBF estimated by using a fixed partition coefficient and CBF estimated using floating partition coefficients (analysis B). The partition coefficient in the infarction area (0.55±0.07 ml/g) was lower than that in the contralateral normal cortex (0.68±0.05 ml/g), whereas noninfarct hypoperfusion area did not show a significant change ...

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2005

Salivary gland dysfunction is one of the common side effects of high-dose radioiodine therapy for... more Salivary gland dysfunction is one of the common side effects of high-dose radioiodine therapy for thyroid cancer. The purpose of this study was to determine whether an early start of sucking lemon candy decreases salivary gland injury after radioiodine therapy. The incidence of the side effects of radioiodine therapy on the salivary glands was prospectively and longitudinally investigated in 2 groups of patients with postsurgical differentiated thyroid cancer with varying regimens for sucking lemon candy. From August 1999 to October 2000, 116 consecutive patients were asked to suck 1 or 2 lemon candies every 2-3 h in the daytime of the first 5 d after radioiodine therapy (group A). Lemon candy sucking was started within 1 h after radioiodine ingestion. From November 2000 to June 2002, 139 consecutive patients (group B) were asked to suck lemon candies in a manner similar to that of group A. In the group B, lemon candies were withheld until 24 h after the ingestion of radioiodine. Pa...

IEEE Nuclear Science Symposium Conference Record, 2005

OSEM is a standard for image reconstruction in positron emission tomography (PET). However, OSEM ... more OSEM is a standard for image reconstruction in positron emission tomography (PET). However, OSEM has not been compared with filtered back projection (FBP) for the quantification of myocardial blood flow (MBF) with 13N-ammonia (NH3) and 82Rb PET. 12 subjects with &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;5% likelihood of CAD had rest and stress (dipyridamole) dynamic PET with NH3 and Rb. Arterial blood and myocardial polar-map

Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology, Jan 14, 2017

FDG PET/CT plays a significant role in the diagnosis of inflammatory heart diseases and cardiac t... more FDG PET/CT plays a significant role in the diagnosis of inflammatory heart diseases and cardiac tumors. We attempted to determine the optimal FDG uptake threshold for volume-based analyses and to evaluate the relationship between the myocardial physiological uptake volume in FDG PET and several clinical factors. A total of 190 patients were retrospectively analyzed. The cardiac metabolic volume (CMV) was defined as a volume within the boundary determined by a threshold (SUVmean of blood pool × 1.5). The SUVmean of the blood pool measured in the descending aorta (DA) (r = 0.86, intraclass correlation coefficient [ICC] = 0.93, P < 0.0001) and that in the left ventricle (LV) cavity (r = 0.87, ICC = 0.90, P < 0.0001) showed high inter-operator reproducibility. However, the SUVmean in the LV cavity showed a significant correlation with the CMV (P = 0.0002, r = 0.26). The CMV in the patients who fasted < 18 hours were significantly higher (49.7 ± 73.2 vs. 18.0 ± 53.8 mL, P = ...

Springer eBooks, 2016

Tumor hypoxia is an important object for imaging because hypoxia is associated with tumor aggress... more Tumor hypoxia is an important object for imaging because hypoxia is associated with tumor aggressiveness and resistance to radiation therapy. Here, 18 Ffluoromisonidazole (FMISO) has been used for many years as the most commonly employed hypoxia imaging tracer. Unlike F-18 fluorodeoxyglucose (FDG), FMISO does not accumulate in normal brain tissue making it able to provide images of hypoxic brain tumors with high contrast. Clinical evidence has suggested that FMISO PET can predict patient prognosis and treatment response. Among gliomas of various grades (WHO 2007), it has been known that grade IV glioblastoma resides under severe hypoxia and is a cause of development of necrosis in the tumor. For this study we tested whether FMISO can distinguish the oxygen condition of glioblastomas and lower-grade gliomas. Twenty-three glioma patients underwent FMISO PET for the study. All the glioblastoma patients (N ¼ 14) showed high FMISO uptakes in the tumor, whereas none of the other patients (i.e., gliomas of grade III or lower, N ¼ 9) did, demonstrated by both qualitative and quantitative assessments. The data suggest that FMISO PET may be a useful tool to distinguish glioblastomas from lower-grade gliomas. Our results, however, were slightly different from previous investigations reporting that some lowergrade gliomas (e.g., grade III) showed positive FMISO uptake. Many of these acquired the FMISO PET images 2 h after the FMISO injection, while for the study here we waited 4 h to be able to collect hypoxia-specific signals rather than perfusion signals as FMISO clearance from plasma is slow due to its lipophilic nature. No optimum uptake time for FMISO has been established, and we directly compared the 2-h vs. the 4-h images with the same patients (N ¼ 17). At 2 h, the gray matter had significantly higher standardized uptake value (SUV) than the white matter, possibly due to different degrees of perfusion but not due to hypoxia. At 4 h, there were no differences between gray and white matter without any significant increase in the noise level measured by the coefficient of variation between the 2-h and the 4-h images. At 2 h, 6/8 (75 %) of glioblastoma patients

PLOS ONE, Dec 9, 2016

Background Bevacizumab (BEV), a humanized monoclonal antibody, become a currently important chemo... more Background Bevacizumab (BEV), a humanized monoclonal antibody, become a currently important chemotherapeutic option for the patients with recurrent glioma. The aim of this retrospective study is to investigate whether 18 F-Fluoromisonidazole (FMISO) PET have the potential to detect BEV-resistant gliomas in the early-stage. Methods We reviewed the FMISO PET and MRI appearances before and 3 to 4 courses after BEV treatment on 18 recurrent glioma patients. FMISO accumulation was assessed by visual inspection and semi-quantitative values which were tumor-to-normal (T/N) ratio and hypoxic volume. MRI responses were evaluated based on RANO (Response Assessment in Neuro-Oncology) criteria. The prognostic analysis was performed in relation to the response assessment by FMISO PET and MRI using overall survival (OS) after BEV application. Results After BEV application, MRI revealed partial response in 14 of 18 patients (78%), of which 9 patients also demonstrated decreased FMISO accumulation. These 9 patients (50%) were classified as "MRI-FMISO double responder". As for the other 5 patients (28%), FMISO accumulation volumes increased or remained stable after BEV treatment although partial responses were achieved on MRI. Therefore, these cases were classified as "MRI-only responder". The remaining 4 patients (22%) did not show treatment response on FMISO PET or MRI ("non-responder"). MRI-FMISO double responders showed significantly longer OS than that in other groups (median 12.4 vs 5.7 months; P < 0.001), whereas there were no overall survival difference between MRI-only responders and non-responders

Japanese Journal of Radiology

Positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) has been commonly used in m... more Positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) has been commonly used in many oncological areas. High-resolution PET permits a three-dimensional analysis of FDG distributions on various lesions in vivo, which can be applied for tissue characterization, risk analysis, and treatment monitoring after chemoradiotherapy and immunotherapy. Metabolic changes can be assessed using the tumor absolute FDG uptake as standardized uptake value (SUV) and metabolic tumor volume (MTV). In addition, tumor heterogeneity assessment can potentially estimate tumor aggressiveness and resistance to chemoradiotherapy. Attempts have been made to quantify intratumoral heterogeneity using radiomics. Recent reports have indicated the clinical feasibility of a dynamic FDG PET-computed tomography (CT) in pilot cohort studies of oncological cases. Dynamic imaging permits the assessment of temporal changes in FDG uptake after administration, which is particularly useful for differentiating p...

Cancer Science, 2021

This is an open access article under the terms of the Creat ive Commo ns Attri bution-NonCo mmerc... more This is an open access article under the terms of the Creat ive Commo ns Attri bution-NonCo mmercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Neuro-Oncology Advances, 2020

Background: Although 11C-Methionine (MET) PET has widely used, 11C-MET tracer has not been approv... more Background: Although 11C-Methionine (MET) PET has widely used, 11C-MET tracer has not been approved in Japan. We conducted multi-center prospective clinical trials using MET for drug approval in diagnosis of brain tumors[Methods] Two trials using 11C-MET PET were performed in Hokkaido University, Osaka University and Fukushima Medical University; 1) Diagnostic accuracy in differentiating tumor recurrence from radiation injury after radiotherapy in brain tumors, 2) The diagnostic efficacy in newly-diagnosed gliomas. 1) The patients with suspected brain tumor recurrence underwent MET and 18F-Fluorodeoxyglucose (FDG) PET. When the target lesion showed MET and/or FDG uptake, the patients underwent target resection for pathological confirmation. Positive prediction values of each tracer uptake were assessed as primary outcome measure, and the sensitivities and specificities of each PET exams were also assessed. 2) The patients with suspected gliomas underwent MET PET. Tissue samplings we...

Cancers, 2021

Positron emission tomography (PET) has unique characteristics for quantitative assessment of tumo... more Positron emission tomography (PET) has unique characteristics for quantitative assessment of tumour biology in vivo. Accumulation of F-18 fluorodeoxyglucose (FDG) may reflect tumour characteristics based on its metabolic activity. Quantitative assessment of FDG uptake can often be applied for treatment monitoring after chemotherapy or chemoradiotherapy. Numerous studies indicated biochemical change assessed by FDG PET as a more sensitive marker than morphological change estimated by CT or MRI. In addition, those with complete metabolic response after therapy may show better disease-free survival and overall survival than those with other responses. Assessment of metabolic change may be performed using absolute FDG uptake in the tumour (standardized uptake value: SUV). In addition, volumetric parameters such as metabolic tumour volume (MTV) have been introduced for quantitative assessment of FDG uptake in tumour. More recently, radiomics approaches that focus on image-based precision...

Journal of Nuclear Medicine, 2017

EJNMMI Research, 2017

Background: The quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR) are... more Background: The quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR) are useful approaches for evaluating the functional severity of coronary artery disease (CAD). 15 O-water positron emission tomography (PET) is considered the gold standard method for MBF quantification. However, MBF measurements in 15 O-water PET with three-dimensional (3D) data acquisition, attenuation correction using computed tomography (CT), and time of flight have not been investigated in detail or validated. We conducted this study to evaluate the diagnostic potential of MBF measurements using PET/CT for a comparison of a control group and patients suspected of having CAD. Results: Twenty-four patients with known or suspected CAD and eight age-matched healthy volunteers underwent rest and pharmacological stress perfusion studies with 15 O-water PET/CT. The whole and three regional (left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) territory) MBF values were estimated. The CFR was computed as the ratio of the MBF during adenosine triphosphate-induced stress to the MBF at rest. The inter-observer variability was assessed by two independent observers. PET/CT using a 15 O-water dose of 500 MBq and 3D data acquisition showed good image quality. A strong inter-observer correlation was detected in both the whole MBF analysis and the regional analysis with high intra-class correlation coefficients (r > 0.90, p < 0.001). Regional MBF at rest (LAD, 0.82 ± 0.15 ml/min/g; LCX, 0.83 ± 0.17 ml/min/g; RCA, 0.71 ± 0.20 ml/min/g; p = 0.74), MBF at stress (LAD, 3.77 ± 1.00 ml/min/g; LCX, 3.56 ± 1.01 ml/min/g; RCA, 3.27 ± 1.04 ml/min/g; p = 0.62), and CFR (LAD, 4.64 ± 0.90; LCX, 4.30 ± 0.64; RCA, 4.64 ± 0.96; p = 0.66) of the healthy volunteers showed no significant difference among the three regions. The global CFR of the patients was significantly lower than that of the volunteers (2.75 ± 0.81 vs. 4.54 ± 0.66, p = 0.0002). The regional analysis of the patients demonstrated that the CFR tended to be lower in the stenotic region compared to the non-stenotic region (2.43 ± 0.81 vs. 2.95 ± 0.92, p = 0.052). Conclusions: 15 O-water PET/CT with 3D data acquisition can be reliably used for the quantification of functional MBF and CFR in CAD patients.

BMC cancer, Jan 2, 2016

Volume-based parameters, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), ... more Volume-based parameters, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), on F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) are useful for predicting treatment response in nonsmall cell lung cancer (NSCLC). We aimed to examine intra- and inter-operator reproducibility to measure the MTV and TLG, and to estimate their dependency on the uptake time. Fifty NSCLC patients underwent preoperative FDG-PET. After an injection of FDG, the whole body was scanned twice: at the early phase (61.4 ± 2.8 min) and delayed phase (117.7 ± 1.6 min). Two operators independently defined the tumor boundary using three different delineation methods: (1) the absolute SUV threshold method (MTVp and TLGp; p = 2.0, 2.5, 3.0, 3.5), (2) the fixed% SUVmax threshold method (MTVq% and TLGq%; q = 35, 40, 45), and (3) the adaptive region-growing method (MTVARG and TLGARG). Parameters were compared between operators and between phases. Both the intra- and inter-operator reprod...

EJNMMI Research, 2017

Background: We aimed to assess the positivity, distribution, quantitative degree of vessel inflam... more Background: We aimed to assess the positivity, distribution, quantitative degree of vessel inflammation, and clinical characteristics of IgG4-related aortitis/periarteritis and periarteritis (IgG4-aortitis), and to examine the difference in these characteristics between cases with and without IgG4-aortitis, using fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) co-registered with contrast-enhanced CT (CECT). We retrospectively evaluated 37 patients with IgG4-related disease (IgG4-RD) who underwent both FDG-PET/CT and CECT. The arterial SUVmax and its value normalized to the background venous blood pool (BP)-the targetto-background ratio (TBR) in the entire aorta and the major first branches-were measured. Active vascular inflammation was considered in cases with a higher FDG uptake than BP and a thickened arterial wall (>2 mm). Results: Fifteen (41%) patients exhibited IgG4-aortitis. Most patients (80%) showed multiple region involvement. The entire aorta, including the major first branches, were involved, typically showing a thickened wall and high FDG uptakes. The most common site was the iliac arteries (35%), followed by the infrarenal abdominal aorta (33%), thoracic aorta (8%), first branches of the thoracic aorta (8%), suprarenal abdominal aorta (6%), and the first branches of the abdominal aorta (5%). The IgG4-aortitis-positive vessel regions were thickened, with an average maximal wall thickness of 6.3 ± 2.9 mm. The SUVmax and TBR values were significantly higher in the IgG4-aortitispositive regions (median 3.7 [1.6-5.5] and 2.1 [1.4-3.7], respectively) than in the IgG4-aortitis-negative regions (median 2.1 [1.2-3.7] and 1.3 [0.9-2.3], respectively; p < 0.0001). The IgG4-aortitis-positive group patients were older (69.5 ± 6.0 vs. 63.3 ± 12.6 years, respectively) and had a higher male predominance (80 vs. 55%, respectively) than the negative group, although the differences were not significant (p = 0.17 and p = 0.06, respectively). Conclusions: We investigated the image characteristics of IgG4-aortitis. The entire aorta and major branches can be involved with more than 2-fold higher FDG uptake than the venous background pool, and with wall thickening. The most common involved site is the iliac arteries, followed by the infrarenal abdominal aorta.

BMC cancer, Jan 15, 2016

Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a benign lymphoid proliferation... more Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a benign lymphoid proliferation or malignant lymphoma in patients who have been treated with MTX. MTX withdrawal and observation for a short period should be considered in the initial management of patients who develop LPD while on MTX therapy. Here we evaluated the diagnostic accuracy and predictive value of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) for MTX-LPD. We retrospectively investigated the cases of 15 patients clinically suspected of having MTX-LPD. A total of 324 anatomic regions (207 nodal and 117 extranodal regions) were assessed by (18)F-FDG PET/CT and by multi-detector row CT (MDCT). Each anatomic region was classified as either malignant or benign. The uptake of (18)F-FDG was assessed semi-quantitatively with the standardized uptake value maximum (SUVmax), the whole-body metabolic tumor volume (WBMTV), and the whole-body total lesion glycolysis (WBTLG) ...

Molecular Imaging for Integrated Medical Therapy and Drug Development, 2010

Objective: Intensity-modulated radiation therapy, an advanced mode of highprecision radiotherapy ... more Objective: Intensity-modulated radiation therapy, an advanced mode of highprecision radiotherapy developed to deliver precise radiation doses to specific areas within a tumor, has become popular in the clinical situation. With this modality, it has become particularly important in the clinical situation to estimate accurate cell activity with positron emission tomography (PET) scanner. We developed a new PET scanner with a semiconductor detector. Phantom images and [18F] fluorodeoxyglucose ([18F] FDG)-PET images of patients were measured to evaluate this new scanner's capacity to identify intratumoral inhomogeneous cell activity. Methods: The semiconductor PET scanner uses CdTe detectors. A cold spot phantom study was performed with 6-mm-diameter cold sphenoid defects. An "H"-shaped phantom, a dual-cylinder phantom, was also studied. These phantoms were surrounded with water. The phantom images and FDG-PET images of eight patients suffering with nasopharyngeal cancer were compared with images from a conventional BGO PET scanner (Siemens HR+). Profile curves of the phantom were measured in the phantom study. Contrast was defined as the peak-to-valley ratio. Intratumoral inhomogeneity and tumor edge sharpness were evaluated on the images of the patients. Results: The contrast obtained with the semiconductor PET scanner (1.53) was 28% higher than that obtained with the HR+ (1.20) for the 6-mm-diameter cold sphenoid phantom. The contrast obtained with the semiconductor PET scanner (1.43) was 27% higher than that obtained with the HR+ (1.13) for the dual-cylinder phantom. Similarly, the 2-mm cold region between 1-mm hot rods in the "H"-shaped phantom was identified only by the new PET scanner and not by the HR+. The new PET scanner identified intratumoral inhomogeneity in more detail than the HR+ in six of the eight patients. The tumor edge was sharper PET with Semiconductor Detector for Head and Neck Cancer 43 on the images obtained with the new PET scanner than on those obtained with the HR+. Conclusion: The new PET scanner has the potential for better identification of intratumoral inhomogeneous cell activity, with high spatial resolution and contrast.

Neurologia medico-chirurgica, 2012

Crossed cerebellar diaschisis (CCD) often occurs after ischemic or hemorrhagic stroke that damage... more Crossed cerebellar diaschisis (CCD) often occurs after ischemic or hemorrhagic stroke that damages the cortico-ponto-cerebellar pathway. However, CCD due to cerebral hyperperfusion following cerebrovascular reconstruction is rare. A 61-year-old woman presented with transient CCD due to cerebral hyperperfusion following bypass surgery for adult moyamoya disease. She developed transient weakness of the right extremities and was diagnosed with moyamoya disease. First, she underwent superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis with indirect synangiosis on the left. Postoperative course was uneventful. Subsequently, she underwent STA-MCA anastomosis with indirect synangiosis on the right. She complained of mild headache on the right, and single photon emission computed tomography (SPECT) performed on the 7th postoperative day demonstrated hyperperfusion in the right frontal and temporal lobes associated with hypoperfusion in the left cerebellum. Magnetic resonance (MR) imaging demonstrated no new lesions and MR angiography showed patent STA-MCA bypass. Subsequent SPECT showed disappearance of both hyperperfusion and CCD. This case strongly suggests that cerebral hyperperfusion after bypass surgery for moyamoya disease may cause transient CCD. Although the clinical significance is still obscure, this phenomenon indicates the cortico-ponto-cerebellar pathway is interrupted due to hyperperfusion, suggesting the development of hyperperfusion syndrome. Careful observation of cerebral hemodynamics after bypass surgery is warranted to avoid hyperperfusion-related complications.

Acta radiologica open, 2015

A 55-year-old woman underwent radiosurgery for a left cerebral hemisphere arteriovenous malformat... more A 55-year-old woman underwent radiosurgery for a left cerebral hemisphere arteriovenous malformation (AVM) and developed radiation-induced necrosis causing a massive edema in the surrounding brain tissues. Despite various therapies, the edema expanded to the ipsilateral hemisphere and induced neurological symptoms. The radiation-induced necrotic lesion was surgically removed 4 years after radiosurgery. While the preoperative FDG PET revealed severe hypometabolism in the left cerebrum, the necrotomy significantly ameliorated the brain edema, glucose metabolism (postoperative FDG PET), and symptoms. This case indicates that radiation necrosis-induced neurological deficits may be associated with brain edema and hypometabolism, which could be reversed by appropriate necrotomy.

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, Jan 4, 2015

The red nucleus (RN) is a pair of small gray matter structures located in the midbrain and involv... more The red nucleus (RN) is a pair of small gray matter structures located in the midbrain and involved in muscle movement and cognitive functions. This retrospective study aimed to investigate the metabolism of human RN and its correlation to other brain regions. We developed a high-resolution semiconductor PET system to image small brain structures. Twenty patients without neurological disorders underwent whole brain scanning after injection of 400 MBq F-18 fluorodeoxyglucose (FDG). The individual brain (18)F-FDG-PET images were spatially normalized to generate a surface projection map using a 3-dimensional stereotactic surface projection (3D-SSP) technique. The correlation between the RN and each voxel on the cerebral and cerebellar cortices was estimated with Pearson's product-moment correlation analysis. Both right and left RNs were visualized with higher uptake than that in the background midbrain. The maximum standardized uptake value (SUVmax) values of RN were 7.64±1.92; the...

World neurosurgery, 2013

Headache is one of the major clinical presentations in pediatric Moyamoya disease. However, the c... more Headache is one of the major clinical presentations in pediatric Moyamoya disease. However, the clinical features and underlying mechanisms are not fully understood. This study aimed to clarify the clinical feature of headache in pediatric Moyamoya disease and the effect of surgical revascularization. This study included 29 pediatric patients who underwent superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect bypass for Moyamoya disease. Their medical records were precisely evaluated to identify the clinical features of their headache. The findings on magnetic resonance imaging, positron emission tomography, and single-photon emission computed tomography also were analyzed. Preoperative headache was documented in 11 (38%) of 29 patients. The majority of them complained of severe headache in the frontal or temporal region in the morning. Headache was significantly related to more advanced disease stage and to the decreases in cerebral blood flow and...

Nuclear medicine communications, 2011

Cerebral blood flow (CBF) estimation with C15O2 PET usually assumes a single tissue compartment m... more Cerebral blood flow (CBF) estimation with C15O2 PET usually assumes a single tissue compartment model and a fixed brain-blood partition coefficient of water. However, the partition coefficient may change in pathological conditions. The purpose of this study was to investigate the changes in the partition coefficient of water in pathological regions and its effect on regional CBF assessment. The study protocol included 22 patients with occlusive cerebrovascular disease to compare the partition coefficients among three regions (infarction area, noninfarct hypoperfusion area, and contralateral area) in the pathological brain (analysis A), and to compare the CBF estimated by using a fixed partition coefficient and CBF estimated using floating partition coefficients (analysis B). The partition coefficient in the infarction area (0.55±0.07 ml/g) was lower than that in the contralateral normal cortex (0.68±0.05 ml/g), whereas noninfarct hypoperfusion area did not show a significant change ...

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2005

Salivary gland dysfunction is one of the common side effects of high-dose radioiodine therapy for... more Salivary gland dysfunction is one of the common side effects of high-dose radioiodine therapy for thyroid cancer. The purpose of this study was to determine whether an early start of sucking lemon candy decreases salivary gland injury after radioiodine therapy. The incidence of the side effects of radioiodine therapy on the salivary glands was prospectively and longitudinally investigated in 2 groups of patients with postsurgical differentiated thyroid cancer with varying regimens for sucking lemon candy. From August 1999 to October 2000, 116 consecutive patients were asked to suck 1 or 2 lemon candies every 2-3 h in the daytime of the first 5 d after radioiodine therapy (group A). Lemon candy sucking was started within 1 h after radioiodine ingestion. From November 2000 to June 2002, 139 consecutive patients (group B) were asked to suck lemon candies in a manner similar to that of group A. In the group B, lemon candies were withheld until 24 h after the ingestion of radioiodine. Pa...