Tachio Sato

Correlation between human personality and neural activity in cerebral cortex.

Personality traits are a variance of behavioral patterns among individuals and may reflect a variance of brain activity, but their neurobiological explanation is still a matter of debate. Cloninger proposed three dimensions of personality traits, each of which has strong correlation with activity in a specific central monoaminergic system. Although this theory has been supported by physiological and genetic studies, it is still unclear how these personality parameters are correlated with the activity of the cortical networks which control human behavior. Here we measured the regional cerebral blood flow (rCBF) at rest in 30 normal volunteers who completed the personality inventory of Cloninger. Voxel-by-voxel analysis was employed to identify cortical regions where the rCBF showed significant correlation with any of the three personality parameters. Statistically significant correlation was observed in several paralimbic and neocortical regions and was consistent with the assumed monoaminergic influence on neural activity and the distribution of its projections, in each personality dimension. The results suggest that activity in a variety of cortical regions is associated with human personality traits and lend support to Cloningers theory concerning central monoaminergic influence on human personality traits.

Assessment of radiotherapeutic effects on experimental tumors using 18F-2-fluoro-2-deoxy-D-glucose

The purpose of this study is to evaluation the effect of tumor volume and radiotherapy on the uptake of 18F-2-fluoro-2-deoxy-D-glucose (18FDG). The tumor models used were mouse mammary carcinoma MM48, FM3A, and rat hepatoma AH109A. Results were expressed as an 18FDG uptake ratio. This was the ratio of irradiated tumor uptake of 18FDG to unirradiated tumor uptake. The total tumor uptake was expressed as 18FDG uptake ratio multiplied by relative tumor volume. Following 20 Gy irradiation of the radioresistant tumor (MM48), the 18FDG uptake ratio was found to be unchanged, whereas in radiosensitive tumors (FM3A) the 18FDG uptake ratio was 0.37, the relative tumor volume was 0.31, and the calculated total tumor uptake was 0.11 on the eighth day after irradiation. The total tumor uptake was lower than the relative tumor volume. AH109A began to regrow after ten Gy irradiation, accompanied by elevated uptake of 18FDG on the seventh day. These results suggest that the 18FDG uptake by tumor is a good marker of radiotherapeutic effects as well as relapses of cancers and is more sensitive than morphological methods.

Experimental study for cancer diagnosis with positron-labeled fluorinated glucose analogs: [18F]-2-fluoro-2-deoxy-D-mannose: A new tracer for cancer detection

Abstract18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) and 18F-2-fluoro-2-deoxy-D-mannose (18F-FDM) were tested as tumor diagnostic agents in a transplantable rat tumor and rabbit tumors. Tissue distribution studies in rats showed high tumor uptakes of both radiopharmaceuticals. The tumor uptake reached 2.65±0.61% dose 18F-FDG/g and 2.65±0.81% dose 18F-FDM/g at 60 min and remained relatively constant until 120 min. Blood clearance of both 18F-FDG and 28F-FDM was very rapid and tumor-to-blood ratios reached 22.1 and 29.4 at 60 min, respectively. Tumor-to-tissue ratios of both radiopharmaceuticals were very high in most organs, especially in the liver, kidney, and pancreas.Positron emission tomography (PET) of rabbit tumor with 18F-FDM clearly delineated the main tumor, central necrosis, and lymph node metastases. These data suggested that 18F-FDM which is a by-product of 18F-FDG synthesis, was also an excellent cancer diagnostic agent as well as 18F-FDG. This is not only a new feature of 18F-FDM, but also an economical improvement on cancer diagnosis by PET.

Diagnostic Evaluation of 67Ga Scanning of Lung Cancer and Other Diseases1

67Ga was the scanning agent in 52 studies: 21 of lung cancer, 11 of tuberculosis, 7 of other lung diseases, 4 of esophageal cancer, 6 of breast disease, and a miscellany of other lesions. The scans clearly delineated infraclavicular lymph node metastases difficult to palpate and lesions in the hili and mediastinum difficult to demonstrate roentgenologically. The 67Ga uptake may result from alterations in vasculature and permeability as well as increased metabolism within and around the disease process.

Studies on 18F-labeled pyrimidines. Tumor uptakes of 18F-5-fluorouracil, 18F-5-fluorouridine, and 18F-5-fluorodeoxyuridine in animals

Three 18F-labeled pyrimidines, 18F-5-fluorouridine (18F-5-FUR), 18F-5-fluorouracil (18F-5-FU), and 18F-5-fluorodeoxyuridine (18F-5-FdUR), were examined regarding tissue distribution and tumor uptake in ascitic hepatoma AH109A-bearing rats. The differential absorption ratios of tumors of 18F-5-FUR, 18F-5-FU, and 18F-5-FdUR were 0.75±0.21, 0.92±0.15, and 0.96±0.24 at 30 min, and 0.37±0.09, 0.64±0.34, and 0.60±0.17 at 120 min, respectively. The tumor-to-organ ratios obtained with three radiopharmaceuticals, especially with blood, heart, lung, muscle, and brain were high and these ratios increased with time. The tumor-to-organ ratios obtained with 18F-5-FdUR were always 1.3–4 times higher than 18F-5-FU and 18F-5-FUR. We concluded that 18F-5-FdUR was a suitable radiopharmaceutical for tumor imaging. Positron emission tomography of a rabbit tumor located on the chest with 18F-5-FdUR clearly showed the tumor within 1 h.

Database of normal human cerebral blood flow measured by SPECT: I. Comparison between I-123-IMP, Tc-99m-HMPAO, and Tc-99m-ECD as referred with O-15 labeled water PET and voxel-based morphometry

ObjectivesThree accumulative tracers, iodine-123-labeledN-isopropyl-p-iodoamphetamine (I-123-IMP), technetium-99m-labeled hexamethylpropyleneamineoxime (Tc-99m-HMPAO), and technetium-99m-labeled ethyl cysteinate dirtier (Tc-99m-ECD) are widely used to measure cerebral blood flow (CBF) in single-photon emission computed tomography (SPECT). In the present study, normal regional distribution of CBF measured with three different SPECT tracers was entered into a database and compared with regional distribution of CBF measured by positron emission tomography (PET) with H215O. The regional distribution of tissue fractions of gray matter determined by voxel-based morphometry was also compared with SPECT and PET CBF distributions.MethodsSPECT studies with I-123-IMP, Tc-99m-HMPAO, and Tc-99m-ECD were performed on 11, 20, and 17 healthy subjects, respectively. PET studies were performed on 11 healthy subjects. Magnetic resonance (MR) imaging studies for voxel-based morphometry were performed on 43 of the 48 subjects who underwent SPECT study. All SPECT, PET, and MR images were transformed into the standard brain format with the SPM2 system. The voxel values of each SPECT and PET image were globally normalized to 50 ml/100 ml/min. Gray matter, white matter, and cerebrospinal fluid images were segmented and extracted from all transformed MR images by applying voxel-based morphometry methods with the SPM2 system.ResultsRegional distribution of all three SPECT tracers differed from that of H215O in the pons, midbrain, thalamus, putamen, parahippocampal gyrus, posterior cingulate gyrus, temporal cortex, and occipital cortex. No significant correlations were observed between the tissue fraction of gray matter and CBF with any tracer.ConclusionDifferences in regional distribution of SPECT tracers were considered to be caused mainly by differences in the mechanism of retention of tracers in the brain. Regional distribution of CBF was independent of regional distribution of gray matter fractions, and consequently the blood flow per gray matter volume differed for each brain region.

67Ga Tumor Scanning and its Mechanisms Studied in Rabbits1

67Ga citrate was used to investigate mechanisms of tumor scanning in rabbits. Both carcinoma and streptococcal abscesses absorbed 67Ga and were visualized on the scans. 67Ga was found to be bound to the protein fraction of the serum. More radioactivity was seen in the soluble fractions of the tumor cells. 67Ga may be carried to tumor cells by the serum protein, taken up rather specifically by tumor cells in a manner which is still unknown, and retained there for some time. Inflammation around the tumor and increased vasculature in the neoplasm may also be significant.

Differential diagnosis of AH109A tumor and inflammation by radioscintigraphy with L-[methyl-11C]methionine.

For the evaluation of tumor imaging with l‐[methyl‐11C]methionine (11C‐Met), a basic study on the differentiation of tumor from inflammation with 11C‐Met and a comparison of the diagnostic value of the image with that obtained using 67Ga citrate, a conventional scintigraphic agent, are important. 11C‐Met accumulations into inflammatory lesions, AH109A tumor and normal tissues of rats were examined by means of a tissue distribution study. Aseptic inflammatory lesions on the back of Donryu rats induced by croton oil and 1.5% carrageenan showed significantly lower accumulations of 11C‐Met than the AH109A tumor. Histologically, croton oil induced granulomatous inflammation and carrageenan, acute exudative inflammation. Whole‐body antoradiography with l4C‐Met, a substitute for 11C‐Met, was negative in the carrageenan lesion and showed a slightly increased activity at the periphery of the croton oil lesion, in contrast with the high tumor activity. Whole‐body autoradiogra‐phy with 67Ga citrate was performed to compare the imaging ability with that of 14C‐Met; it showed high activities in the tumor, bone, and intestine, and a broad increased activity at the periphery of the croton oil lesion, but was negative in the carrageenan lesion. 11C‐Met accumulations in the inflammations were very low and clinical application with positron emission tomography, should be useful for the differential diagnosis of tumor from inflammation.

Apparent CBF decrease with normal aging due to partial volume effects: MR-based partial volume correction on CBF SPECT

Several studies using single photon emission tomography (SPECT) have shown changes in cerebral blood flow (CBF) with age, which were associated with partial volume effects by some authors. Some studies have also demonstrated gender-related differences in CBF. The present study aimed to examine age and gender effects on CBF SPECT images obtained using the99mTc-ethyl cysteinate dimer and a SPECT scanner, before and after partial volume correction (PVC) using magnetic resonance (MR) imaging. Forty-four healthy subjects (29 males and 15 females; age range, 27-64 y; mean age, 50.0 ± 9.8 y) participated. Each MR image was segmented to yield grey and white matter images and coregistered to a corresponding SPECT image, followed by convolution to approximate the SPECT spatial resolution. PVC-SPECT images were produced using the convoluted grey matter MR (GM-MR) and white matter MR images. The age and gender effects were assessed using SPM99. Decreases with age were detected in the anterolateral prefrontal cortex and in areas along the lateral sulcus and the lateral ventricle, bilaterally, in the GM-MR images and the SPECT images. In the PVC-SPECT images, decreases in CBF in the lateral prefrontal cortex lost their statistical significance. Decreases in CBF with age found along the lateral sulcus and the lateral ventricle, on the other hand, remained statistically significant, but observation of the spatially normalized MR images suggests that these findings are associated with the dilatation of the lateral sulcus and lateral ventricle, which was not completely compensated for by the spatial normalization procedure. Our present study demonstrated that age effects on CBF in healthy subjects could reflect morphological differences with age in grey matter.

Sclerosing mediastinitis: findings on fluorine-18 fluorodeoxyglucose positron emission tomography.

Whole-body serial positron emission tomography scanning was done using fluorine-18 fluorodeoxyglucose (F-18 FDG) in a patient with a mediastinal mass. Uptake correlated well with the clinical symptoms and aggressiveness of the disease. Based on the F-18 FDG findings, a biopsy specimen was taken from the active region of the mass, which confirmed the diagnosis of sclerosing mediastinitis.