Search PubMed⌕ Search

Biomedical subjects

Nagara Tamaki

Publications and source records attributed to Nagara Tamaki.

At least 73 records · Page 4Linked to original sources
PubMed2003

[Chronic heart failure assessed by nuclear medicine].

Radionuclide imaging has been used for comprehensive evaluation of patients with heart failure. First of all, radionuclice ventriculography is useful for objective and quantitative assessment of LV systolic function. This is particularly important for assessment of severity of the disease and treatment effects. Radionuclide myocardial imaging permits evaluation of cellular and molecular function of the heart failure, including myocardial viability on the basis of membrane integration or preservation of myocardial metabolism. The combination of oxidative metabolism and cardiac workload may provide objective assessment of myocardial energy efficiency. Furthermore, recent developments of new radiopharmaceuticals permit noninvasive assessment of adrenergic neuronal function and beta-receptor function in vivo. The severity of the adrenergic dysfunction in patients with heart failure may be related the outcome of these patients. Such analysis may be valuable for evaluation of treatment effects and may possibly provide the best treatment for each patient with heart failure.

Chronic Disease↗
PubMed2003

Characteristic brain distribution of 1-(14)C-octanoate in a rat model of focal cerebral ischemia in comparison with those of (123)I-IMP and (123)I-iomazenil.

UNLABELLED: 1-(11)C-Octanoate is a potential tracer for studying astroglial function in PET. To evaluate the usefulness of 1-(11)C-octanoate for studying ischemic stroke, we investigated the brain distribution of 1-(14)C-octanoate and compared it with N-isopropyl-p-(123)I-iodoamphetamine ((123)I-IMP) distribution (cerebral blood flow), (123)I-iomazenil ((123)I-IMZ) distribution (neuronal viability based on (123)I-IMZ binding to benzodiazepine receptors), and hematoxylin-eosin stain (morphologic changes) in a rat model of focal cerebral ischemia. METHODS: The right middle cerebral artery of each rat was occluded intraluminally. The brain distribution of 1-(14)C-octanoate and (123)I-IMP (or (123)I-IMZ) was determined 4 and 24 h after the insult using a dual-tracer autoradiographic technique (n = 4-7 in each group). Coronal brain sections adjacent to those used for autoradiography were stained with hematoxylin and eosin. Regions of interest (ROIs) were determined for 3 coronal slices, and asymmetry indices (AIs, lesion/normal hemisphere) of the tracer uptake were calculated. ROIs on the hemisphere with the lesion were classified into 4 groups: In region A, widespread necrotic cells were observed; in region B, necrotic cells were occasionally observed; in region C1, no morphologic changes were observed and the AIs for (123)I-IMP (or (123)I-IMZ) were 0.8. RESULTS: 1-(14)C-Octanoate uptake decreased in the regions where morphologic changes were observed (regions A and B) but was relatively preserved in the surrounding region without morphologic changes despite reduced (123)I-IMP and (123)I-IMZ uptake (region C1). In the region without morphologic changes (region C1), AIs for 1-(14)C-octanoate were significantly higher than those for (123)I-IMP (4 h, 0.73 +/- 0.23 for 1-(14)C-octanoate and 0.37 +/- 0.20 for (123)I-IMP, P < 0.0001; 24 h, 0.84 +/- 0.11 for 1-(14)C-octanoate and 0.44 +/- 0.15 for (123)I-IMP, P < 0.0001) and those for (123)I-IMZ (4 h, 0.83 +/- 0.19 for 1-(14)C-octanoate and 0.57 +/- 0.13 for (123)I-IMZ, P < 0.0001; 24 h, 0.91 +/- 0.13 for 1-(14)C-octanoate and 0.73 +/- 0.06 for (123)I-IMZ, P < 0.0001). CONCLUSION: 1-(14)C-Octanoate uptake was relatively preserved in the regions without morphologic changes despite reduced (123)I-IMP and (123)I-IMZ uptake. 1-(11)C-Octanoate may provide further functional information on the pathophysiology of ischemic stroke, reflecting astroglial function based on fatty acid metabolism.

Animals↗
PubMed2003

[Phase III additional clinical study of 111In-pentetreotide (MP-1727): diagnosis of gastrointestinal hormone producing tumors based on the presence of somatostatin receptors].

Additional phase III multicenter clinical study was performed to investigate the efficacy, safety, and usefulness of somatostatin receptor scintigraphy using 111In-pentetreotide (MP-1727), which binds to somatostatin receptors. Forty patients were included in the study; Group A: 18 patients, gastrointestinal hormone producing tumors had been detected with conventional imaging modalities, Group B: 22 patients, no tumors had been detected with conventional imaging modalities in spite of high serum hormone levels. By comparing the results of the octreotide suppression test, 12/16 cases (75.0%) of Group A and 11/19 cases (57.9%) of Group B were assessed as "effective." By comparing the results of immunohistological examination, 5/9 cases (55.6%) of Group A and 2/4 cases (50.0%) of Group B were assessed as "effective." Severe adverse events were not observed in any of the evaluable 35 cases. MP-1727 was judged as clinically useful in 11/16 cases (68.8%) of Group A and 5/19 cases (26.3%) of group B. These results suggest that MP-1727 scintigraphy is very useful for the diagnosis and decision of the therapeutic strategy of gastrointestinal hormone producing tumors.

Aged↗
PubMed2003

[Normalization of cerebral hemodynamics and metabolism after carotid stenting in patients unfit for major surgery].

There is increasing evidence that stenting is a useful strategy for internal carotid artery (ICA) stenosis in patients unfit for drastic surgery. However, it should be remembered that perioperative complications including seizure or intracerebral hemorrhage due to hyperperfusion are not so rare. The authors describe a case with severe ICA stenosis, who successfully underwent stenting as a result of intensive medical care for postoperative hyperperfusion. A 77-year-old man with a recent history of angina pectoris and transient ischemic attack was referred to our hospital. Cerebral angiography showed subtotal occlusion of the left ICA. SPECT/PET studies revealed a disturbed reactivity to acetazolamide and an increase in regional oxygen extraction fraction in the left hemisphere, suggesting a marked reduction in cerebral perfusion pressure. He successfully underwent carotid stenting. Intraoperative near-infrared monitoring showed an increase in the concentration of total and oxidized hemoglobin in the left frontal area after stenting. A SPECT study just after stenting also demonstrated hyperperfusion in the left middle cerebral artery territory. His blood pressure was carefully controlled to avoid "hyperperfusion syndrome" including headache, seizure and intracerebral hemorrhage. Follow-up SPECT/PET studies showed a normalization of hemodynamic and metabolic parameters. SPECT/PET studies are quite valuable to predict and prevent hyperperfusion syndrome after carotid stenting, and result in good clinical outcome.

Aged↗
PubMed2002

Estimation of myocardial blood flow and myocardial flow reserve by 99mTc-sestamibi imaging: comparison with the results of [15O]H2O PET.

We developed a noninvasive method to quantitatively estimate the myocardial blood flow (MBF) index and flow reserve (MFR) using dynamic and static data obtained with technetium-99m sestamibi, and compared the results with MBF and MFR measured by oxygen-15-labeled water ([(15)O]H(2)O) PET. Twenty patients with coronary artery disease (CAD) and nine normal subjects underwent both (99m)Tc-sestamibi and PET studies within 2 weeks. From the anterior view, dynamic data were acquired for 2 min immediately after the injection of (99m)Tc-sestamibi, and planar static images were also obtained after 5 min at rest and during ATP stress (0.16 mg kg(-1) min(-1) for 5 min) on another day. The area under the time-activity curve on the aortic arch (Aorta ACU), myocardial weight with the SPET image (M), and the myocardial count on the planar image for 1 min (C(m)) were obtained. The MBF index (MBFI) was calculated as follows: MBFI=Cm/Aorta ACU x 100M. MFR was measured by dividing the MBFI at ATP stress by MBFI at rest. The MBFI measured by (99m)Tc-sestamibi was significantly correlated with MBF obtained using [(15)O]H(2)O PET (MBFI=13.174+11.732 x MBF, r=0.821, P<0.001). Furthermore, MFR measured by (99m)Tc-sestamibi was well correlated with that obtained using [(15)O]H(2)O PET, with some underestimation (r=0.845, P<0.001). MFR using (99m)Tc-sestamibi in patients with CAD was significantly lower than that in normal subjects (CAD: 1.484+/-0.256 vs normal: 2.127+/-0.308, P<0.001). These data suggest that the MBFI and MFR can be measured with (99m)Tc-sestamibi. This may be useful for the quantitative assessment of CAD, especially in those patients with diffuse coronary disease.

Adult↗
PubMed2002

Accumulation of [11C]acetate in normal prostate and benign prostatic hyperplasia: comparison with prostate cancer.

Carbon-11 acetate positron emission tomography (PET) has been reported to be of clinical value for the diagnosis of prostate cancer. However, no detailed analysis has yet been carried out on the physiological accumulation of [(11)C]acetate in the prostate. The purpose of this study was to elucidate the physiological accumulation of [(11)C]acetate in the prostate using dynamic PET. The study included 30 subjects without prostate cancer [21 with normal prostate and nine with benign prostatic hyperplasia (BPH)] and six patients with prostate cancer. A dynamic PET study was performed for 20 min after intravenous administration of 555 MBq of [(11)C]acetate. The standardised uptake value (SUV) at 16-20 min post tracer administration and the early-to-late-activity ratio of the SUV (E/L ratio), which was determined by dividing the SUV(6-10 min) by the SUV(16-20min), were calculated to evaluate the accumulation of [(11)C]acetate. The prostate was clearly visualised and distinguished from adjacent organs in PET images in most of the cases. The SUV of the prostate (2.6+/-0.8) was significantly higher than that of the rectum (1.7+/-0.4) or bone marrow (1.3+/-0.3) ( P<0.0001 in each case). The SUV of the normal prostate of subjects aged <50 years (3.4+/-0.7) was significantly higher than both the SUV for the normal prostate of subjects aged > or =50 years (2.3+/-0.7) and that of subjects with BPH (2.1+/-0.6) ( P<0.01 in each case). The primary prostate cancer in six cases was visualised by [(11)C]acetate PET. However, the difference in the SUV between subjects aged > or =50 with normal prostate or with BPH and the patients with prostate cancer (1.9+/-0.6) was not statistically significant. There was also no significant difference in the E/L ratio between subjects aged > or =50 with normal prostate (0.98+/-0.04) or BPH (0.96+/-0.08) and patients with prostate cancer (1.02+/-0.12). In conclusion, a normal prostate exhibits age-related physiological accumulation of [(11)C]acetate. Careful interpretation of [(11)C]acetate PET images of prostate cancer is necessary because the SUV and the E/L ratio for the normal prostate and for BPH overlap significantly with those for prostate cancer.

Acetates↗
PubMed2002

Assessment of coronary function in children with a history of Kawasaki disease using (15)O-water positron emission tomography.

BACKGROUND: Coronary abnormalities after Kawasaki disease (KD) may be associated with endothelial dysfunction due to intimal hypertrophy. The purpose of this study was to evaluate myocardial flow reserve (MFR) and endothelial function in regressed aneurysmal regions after KD. Methods and Results- Subjects were 12 patients aged 16.0+/-2.6 years who suffered from KD at 1.7+/-1.5 years and 12 normal subjects aged 26.5+/-3.4 years. MFR and endothelial function were estimated, respectively, by changes in myocardial blood flow (MBF) during ATP infusion and by that during cold pressor test using (15)O-water positron emission tomography. Data from 24 regressed aneurysmal regions were compared with those from the corresponding regions (n=36) in the control group. Although the MBF at rest in the regressed aneurysmal regions was similar to that in controls, the MBF at a hyperemic state induced by ATP infusion in the regressed aneurysmal regions was significantly lower than that in the control regions. Therefore, the MFR in regressed aneurysmal regions was significantly lower than that in controls (3.53+/-0.95 versus 4.60+/-1.14; P<0.05). MBF at rest and during the cold pressor test did not change in the control regions, but it was significantly reduced in regressed aneurysmal regions. The ratio of MBF during the cold pressor test to MBF at rest was significantly lower in regressed aneurysmal regions than in control regions (0.67+/-0.15 versus 1.00+/-0.15; P<0.05). CONCLUSIONS: MFR and endothelial function are often impaired in regressed aneurysmal regions after KD, and tomography enables the noninvasive evaluation of coronary function.

Adenosine Triphosphate↗
PubMed2002

Clinical role of (18)F-FDG PET for initial staging of patients with extrahepatic bile duct cancer.

In extrahepatic bile duct cancer, preoperative evaluation is important because only surgical excision of all detectable tumours is associated with improvement in 5-year survival. However, morphological imaging techniques, including computed tomography (CT), are still insufficient for accurate staging. The purpose of this study was to assess the additional value, in relation to CT, of 2-[(18)F]fluoro-2-deoxy- D-glucose positron emission tomography ((18)F-FDG PET) for the evaluation of extrahepatic bile duct cancer. Thirty patients with extrahepatic bile duct cancer underwent both (18)F-FDG PET and CT for initial staging. The results of the two modalities for evaluation of primary tumours and regional lymph nodes were compared with the final diagnoses based on pathological or clinical findings. The primary tumours were interpreted as malignant on the basis of CT in 24 (80%) of the patients, while (18)F-FDG PET revealed increased (18)F-FDG uptake in 18 (60%) of them. On the other hand, (18)F-FDG PET showed focal accumulation of (18)F-FDG in the bile duct in three of the six patients with equivocal findings on CT. The sensitivity, specificity and accuracy of CT for regional lymph node metastases were 54%, 59% and 57%, while those of (18)F-FDG PET were 38%, 100% and 73%, respectively. The specificity of (18)F-FDG PET for regional lymph node metastases was significantly higher than that of CT ( P<0.01). Of 14 patients with N1 or N2 disease diagnosed by CT, only seven (50%) had a final diagnosis of regional lymph node metastasis. In these 14 patients, (18)F-FDG PET accurately evaluated the N component of the disease in 12 patients (86%). In conclusion, in the initial staging of patients with extrahepatic bile duct cancer, (18)F-FDG PET offers additional value in relation to CT in evaluating both the primary tumour and regional lymph nodes.

Adenocarcinoma↗
PubMed2002

Norepinephrine transporter density as a causative factor in alterations in MIBG myocardial uptake in NIDDM model rats.

Cardiac scintigraphic studies with iodine-123 labeled metaiodobenzylguanidine ([(123)I]MIBG) have demonstrated global and regionally pronounced decreases in myocardial accumulation of radioactivity in diabetes. The aim of this study was to investigate the cause of the regional differential decrease in accumulation. To this end, we investigated the global and regional myocardial distribution of [(125)I]MIBG in GK/Crj (GK) rats [a model of non-insulin-dependent diabetes mellitus (NIDDM)] and assessed the responsibility of regional myocardial blood flow, myocardial and plasma norepinephrine (NE) content, and norepinephrine transporter (NET) function for the regional variations in [(125)I]MIBG accumulation. To investigate the responsibility of myocardial blood flow for the alterations in MIBG accumulation, dual-isotope autoradiographic studies with [(125)I]MIBG and technetium-99m hexakis-2-methoxy-2-isobutylisonitrile (MIBI), a tracer for the measurement of myocardial blood flow, were carried out in GK rats and control rats. The results in respect of the uptake of radioactivity into various myocardial regions were expressed as distribution absorption ratios [DAR = (radioactivity of tissue/g of tissue) x (body weight/total injected dose)]. In control rats, uptake of [(125)I]MIBG was significantly higher in the inferior wall than in the anterior wall (anterior wall, 6.35 +/- 0.90; inferior wall, 8.12 +/- 1.27: P < 0.001). On the other hand, in GK rats, uptake of [(125)I]MIBG was similar between the anterior wall and the inferior wall (anterior wall, 4.91 +/- 0.71; inferior wall, 4.81 +/- 0.69). Compared with control rats, uptake of [(125)I]MIBG in GK rats was decreased in both the anterior wall and the inferior wall. Uptake of (99m)Tc-MIBI was not significantly different between the anterior and inferior walls in control (anterior wall, 17.9 +/- 4.42; inferior wall, 18.1 +/- 4.52) and GK rats (anterior wall, 16.6 +/-8.03; inferior wall, 16.7 +/- 7.90), indicating that myocardial blood flow did not change regionally in either control or GK rats, and that the blood flow was not responsible for the differential decrease in MIBG accumulation in GK rats. Cardiac and plasma NE levels were measured using an HPLC-electrochemical detection system. The cardiac and plasma NE concentrations were not significantly different between control (anterior wall, 347 +/- 56 ng/g; inferior wall, 354 +/- 31 ng/g; plasma 9.38 +/- 2.10 ng/ml) and GK rats (anterior wall, 323 +/- 62 ng/g; inferior wall, 344 +/- 35 ng/g; plasma, 9.41 +/- 2.39 ng/ml). The density and affinity of NET were investigated by studying the binding of [(3)H]desipramine to cardiac membranes. The B(max) (fmol/mg protein) in the inferior wall was significantly higher than that in the anterior wall in the control rats (anterior wall, 364 +/- 28; inferior wall, 459 +/- 36: P < 0.05). On the other hand, there was no significant difference in the B(max) value between the anterior and inferior walls in GK rats (anterior wall, 263 +/- 42; inferior wall, 251 +/- 27). In conclusion, myocardial MIBG uptake was differentially reduced in GK rats, and this decrease was associated with a decrease in NET density, but the regional myocardial blood flow and the NE concentration were not responsible for the alterations in MIBG uptake. Thus, NET density was identified as the factor responsible for decreases in MIBG accumulation.

3-Iodobenzylguanidine↗
PubMed2002

Decreased endothelium-dependent coronary vasomotion in healthy young smokers.

Chronic cigarette smoking alters coronary vascular endothelial response. To determine whether altered response also occurs in young individuals without manifest coronary disease we quantified coronary blood flow at rest, following adenosine vasodilator stress and during the cold pressor test in healthy young smokers. Myocardial blood flow (MBF) was quantified by oxygen-15 labelled water positron emission tomography in 30 healthy men aged from 20 to 35 years (18 smokers and 12 non-smokers, aged 27.4 +/- 4.4 vs 26.3 +/- 3.3). The smokers had been smoking cigarettes for 9.4 +/- 4.9 pack-years. MBF was measured at rest, during intravenous adenosine triphosphate (ATP: 0.16 mg kg(-1) min(-1)) infusion (hyperaemic response), and during cold pressor test (CPT) (endothelial vasodilator response). Rest MBF and hyperaemic MBF did not differ significantly between the smokers and the non-smokers (rest: 0.86 +/- 0.11 vs 0.92 +/- 0.14 and ATP: 3.20 +/- 1.12 vs 3.69 +/- 0.76 ml g(-1) min(-1); P = NS). Coronary flow reserve was similar between the two groups (smokers: 3.78 +/- 1.83; non-smokers: 4.03 +/- 0.68; P = NS). Although CPT induced a similar increase in rate-pressure product (RPP) in the smokers and the non-smokers (10,430 +/- 1,820 vs 9,236 +/- 1,356 beats min(-1) mmHg(-1)), CPT MBF corrected by RPP was significantly decreased in the smokers (0.65 +/- 0.12 ml g(-1) min(-1)) compared with the non-smokers (0.87 +/- 0.12 ml g(-1) min(-1)) ( P < 0.05). In addition, the ratio of CPT MBF to resting MBF was inversely correlated with pack-years ( r = -0.57, P = 0.014). Endothelium-dependent coronary artery vasodilator function is impaired in apparently healthy young smokers.

Adenosine Triphosphate↗
PubMed2002

Low-dose dobutamine stress gated SPET for identification of viable myocardium: comparison with stress-rest perfusion SPET and PET.

The detection of viable myocardium is important for the prediction of functional recovery after revascularisation. However, a fixed perfusion defect often includes viable myocardium, and perfusion imaging then underestimates myocardial viability. We previously reported that low-dose dobutamine stress gated single-photon emission tomography (SPET) provides similar findings to dobutamine stress echocardiography in the assessment of myocardial viability. The present study investigated whether low-dose dobutamine stress gated SPET is of additional value as compared with stress-rest technetium-99m tetrofosmin SPET for the detection of myocardial viability. Standard stress-rest perfusion SPET, low-dose dobutamine stress gated SPET and fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) were studied in 23 patients (mean age 67+/-7.6 years) with previous myocardial infarction. Twenty-one of them were successfully studied with each technique. FDG PET viability (FDG uptake >/=50%) was employed as the gold standard. One-day stress-rest (99m)Tc-tetrofosmin myocardial SPET was performed. After the resting study, gated SPET was acquired following infusion of 7.5 microg kg(-1) min(-1) of dobutamine. Left ventricular wall motion in 16 segments was assessed by cine mode display using a four-point scale. Myocardial viability was considered present when there was improvement by one point. Of a total of 336 segments analysed, 53 had persistent defects on stress-rest perfusion SPET. FDG viability was seen in 16 of 17 dobutamine-responsive segments, but in only 11 of 36 dobutamine non-responsive segments ( P<0.01). Thus, in the segments with persistent defects, viability findings on low-dose dobutamine stress gated SPET were concordant with those on FDG PET in 77% of segments (kappa value =0.55). For the detection of FDG-viable myocardium, the combination of stress-rest perfusion SPET and low-dose dobutamine stress gated SPET achieved a better sensitivity than stress-rest perfusion SPET alone (35/46, 76% vs 19/46, 41.3%, P<0.001), with a similar specificity (25/29, 86% vs 26/29, 90%, P=NS). We conclude that in the identification of viable myocardium, low-dose dobutamine stress gated SPET may provide additional information missed on a routine stress-rest perfusion scan. Dobutamine stress gated SPET may provide new insights into myocardial viability on the basis of ischaemia and contractile reserve.

Aged↗
PubMed2002

Accuracy of plasma sample methods for determination of glomerular filtration rate with 99mTc-DTPA.

UNLABELLED: The plasma sample method following a single injection of radioactive markers has been proved to be simple and accurate for the determination of glomerular filtration rate (GFR) in clinical practice. The aim of this study was to assess clinical accuracy of single-, two- and multi-sample methods. METHODS: The study was performed on 50 patients with various degrees of renal dysfunction (29 males and 21 females; aged 27 to 90 years). As a reference the true GFR (GFRt) was determined by means of the two-compartment model curve fitting 10 plasma samples following a single-injection of 99mTc-DTPA. The GFRt was compared to the GFR estimated by the Christensen and Groth's single-sample (GFRcg), two-sample (GFR2s) and multi-sample (GFRm) between 75 and 300 min after the injection. The GFRs by two- and multi-sample methods were determined with the slope and intercept algorithm and its overestimation was corrected by Brochner-Mortensen's formula. RESULTS: In 49 patients with GFR between 12 and 169 ml/min/1.73 m2, the standard deviation of difference (95% limits of agreement) between GFRt and GFRcg at 180 min was 6.513 ml/min/l73 m2 (-16.5 approximately 9.5 ml/min/1.73 m2), which was somewhat closer than 7.311 ml/min/1.73 m2 (-12.5 approximately 16.5 ml/min/1.73 m2) in GFR2s in slow clearance phase at 120 min and 240 min. However, the single-sample method tended to show some scattering in GFR below 30 and above 140 ml/min/ 1.73 m2. On the contrary, the 2-sample method tended to be scattered in GFR above 120 ml/min/ 1.73 m2. CONCLUSION: In view of its accuracy and technical simplicity, the single-sample method is first choice in a routine practice. The two-sample method is essential of choice for a patient in whom the GFR is expected to be below 30 ml/min/1.73 mi2. These two methods may be chosen selectively in dependence on the preserved renal function which is expected at time of the test.

Adult↗
PubMed2002

The effect of scatter correction on 123I-IMP brain perfusion SPET with the triple energy window method in normal subjects using SPM analysis.

Scatter correction (SC) using the triple energy window method (TEW) has recently been applied for brain perfusion single-photon emission tomography (SPET). The aim of this study was to investigate the effect of scatter correction using TEW on N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) SPET in normal subjects. The study population consisted of 15 right-handed normal subjects. SPET data were acquired from 20 min to 40 min after the injection of 167 MBq of IMP, using a triple-head gamma camera. Images were reconstructed with and without SC. 3D T1-weighted magnetic resonance (MR) images were also obtained with a 1.5-Tesla scanner. First, IMP images with and without SC were co-registered to the 3D MRI. Second, the two co-registered IMP images were normalised using SPM96. A t statistic image for the contrast condition effect was constructed. We investigated areas using a voxel-level threshold of 0.001, with a corrected threshold of 0.05. Compared with results obtained without SC, the IMP distribution with SC was significantly decreased in the peripheral areas of the cerebellum, the cortex and the ventricle, and also in the lateral occipital cortex and the base of the temporal lobe. On the other hand, the IMP distribution with SC was significantly increased in the anterior and posterior cingulate cortex, the insular cortex and the medial part of the thalamus. It is concluded that differences in the IMP distribution with and without SC exist not only in the peripheral areas of the cerebellum, the cortex and the ventricle but also in the occipital lobe, the base of the temporal lobe, the insular cortex, the medial part of the thalamus, and the anterior and posterior cingulate cortex. This needs to be recognised for adequate interpretation of IMP brain perfusion SPET after scatter correction.

Adult↗
PubMed2002

Human brain region response to distention or cold stimulation of the bladder: a positron emission tomography study.

PURPOSE: Several kinds of perceptions, including distention and coldness, arise from the bladder. Information on bladder fullness conveyed by mechanoreceptors within the bladder wall contributes to the basic micturition reflex via the bulbospinal reflex pathway, whereas cold stimulation of the bladder is processed differently. To elucidate the human brain mechanisms of voluntary urine storage and bladder cold perception we performed positron emission tomography scanning to examine brain regions activated by bladder distention or cold stimulation. MATERIALS AND METHODS: A total of 17 right-handed healthy male volunteers were catheterized via the urethra for bladder infusion. Subjects were divided into 2 groups for 2 types of positron emission tomography, namely the bladder distention group-11 who were 24 to 41 years old and the intravesical ice water group-6 who were 24 to 38 years old. Data were analyzed by the statistical parametric mapping procedure. RESULTS: Significant brain activation during maximum urine storage (bladder distention) were found in the pons, midbrain periaqueductal gray, anterior insula, putamen, thalamus and anterior cingulate gyrus. On the other hand, intravesical ice water instillation significantly activated several regions in frontal and parietal lobes, amygdala-hippocampus area and crus cerebri ventral border. Distribution of the activated regions after intravesical instillation of ice water overlapped none of those observed after bladder distention. CONCLUSIONS: Our data show that the brainstem as well as more rostral regions are involved in voluntary urine storage and these regions are functionally separated from those associated with bladder cold perception in healthy individuals.

Adult↗
PubMed2002

Increased [18F]2-fluoro-2-deoxy-D-glucose ([18F]FDG) yield with recycled target [18O]water: factors affecting the [18F]FDG yield.

The reuse of [18O] water after being purified by distillation has been reported to give lower [18F]2-fluoro-2-deoxy-D-glucose ([18F]FDG) yields, probably due to the presence of organic impurities. In our routine production of [18F]FDG, however, we observed increased [18F]FDG yields with recycled [18O]water. Thus, factors affecting [18F]FDG yield were examined using as-purchased (virgin) and recycled (by photochemical combustion and distillation) [18O]water. [18F]FDG was synthesized by nucleophilic 18F-fluorination on a quaternary 4-aminopyridinium resin. The recycled [18O]water gave an [18F]FDG yield significantly higher than did the virgin water, without any significant difference in the [18F]fluoride yield. Levels of several ionic impurities including Cl- and Ca2+ were significantly higher in the virgin [18O]water than in the recycled water, while significantly larger amounts of organic impurities were detected in the former. Hence, trace amounts of organic impurities were not responsible for the lower [18F]FDG yield. Chloride anion in the [18O]water may compete with [18F]fluoride to lower the [18F]FDG yield.

Journal Article↗
PubMed2002

Chemical impurities in [18F]FDG preparations produced by solid-phase 18F-fluorination.

[18F]FDG was produced by solid-phase 18F-fluorination (resin method) and chemical impurities were determined in the [18F]FDG preparations by ion chromatography. The major chemical impurities were D-glucose (90.5 +/- 6.4 microg/mL), 2-chloro-2-deoxy-D-glucose (11.8 +/- 2.7 microg/mL), and D-mannose (1.7 +/- 0.7 microg/mL), which were expected to be present by considering the synthetic routes. An FDG mass (0.5 +/- 0.2 microg/mL) was also detected in the preparations. No notable radiochemical impurities, including 2-[18F]fluoro-2-deoxy-D-mannose, were detected in the [18F]FDG preparations. Thus, the levels of several chemical impurities were determined in the [18F]FDG preparations produced by solid-phase 18F-fluorination.

Chromatography, Ion Exchange↗