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A multicenter cooperation phantom study was conducted to evaluate the accuracy of a triple energy window scatter correction technique in combination with various attenuation correction methods for 99mTc single photon emission computed tomography (SPECT) imaging. Six centers participated in this research and the data obtained with seven SPECT instruments were analyzed. The phantom used in the experiment was a 20 x 10 cm cylinder filled with homogeneous 99mTc solution, containing two kinds of cold spots (cold rod phantoms). One had a water-filled cylinder 5.5 cm in diameter positioned 2.5 cm from the center. The other contained 6 water-filled cylinders of various sizes. Contrasts of cold regions were in the range from 74% to 120% (true 100%). Another phantom had the shape of a pie-chart divided into six chambers symmetrically positioned in a cylinder 20 cm in diameter and 10 cm in height. Each chamber had volume of 480 ml and contained homogeneous 99mTc solution of different concentrations. This phantom was used to test for linearity between the radio activity concentration and reconstructed count density (linearity phantom). The intercept of the regression line obtained from the linearity phantom was 8.4 kBq ml-1 without scatter correction and -6.8 kBq ml-1 with scatter correction. Contrast was in the range from 78% to 132% (true 100%). The mean relative error for the measured activity concentration was 4.9% +/- 3.5% (mean +/- sd).

Statistical parametric mapping (SPM) has been developed by Friston et al. to analyze focal changes in regional cerebral blood flow (rCBF) induced by brain activation. This automated and objective approach has the potential of being applied to single photon emission computed tomography (SPECT) image data sets. This study evaluated an automated analysis of N-isopropyl-p[123I]iodoamphetamine SPECT (123I-IMP) imaging in patients with dementia of Alzheimer's type (DAT) using statistical parametric mapping '95 (SPM'95). Eighteen patients with clinically diagnosed mild to severe DAT who were classified into two groups and ten normal control subjects were studied. The SPECT device used was a triple-headed rotation gamma camera. All images were transformed into the standard anatomical space of the stereotaxic brain atlas of Talairach and Tournoux, and then smoothed. Statistical analyses were made between severe DAT, mild DAT and normal control groups. SPM analysis of 123I-IMP SPECT images revealed that the parietotemporal association areas and posterior cingulate gyri of both cerebral hemispheres were significantly decreased in CBF in mild DAT group compared to normal controls. In comparison of DAT groups, the right hippocampal area and basal forebrain were significantly decreased in CBF in severe DAT group. In conclusion, these results obtained by SPM analysis of SPECT images suggested that the right hippocampal area and basal forebrain followed the parietotemporal association areas and posterior cingulate gyri in the reduction of the rCBF in patients with DAT.

Statistical parametric map (SPM) has been developed by Friston et al. to analyze focal changes in rCBF induced by brain activation. This automated and objective approach has the potential of being applied to SPECT image data sets. This study evaluated an automated analysis of brain SPECT imaging in patients with dementia of Alzheimer type (DAT) using SPM95. Seventeen patients with clinically diagnosed moderate to severe DAT and nine normal control subjects were studied. The SPECT device used was a triple-headed rotation gamma camera GCA9300A/HG. All images were transformed into the standard anatomical space of the stereotactic brain atlas of Talairach and Tournoux, and then smoothed. Statistical analysis was made between DAT and normal control groups. SPM analysis of SPECT images revealed that the parieto-temporal areas and posterior cingulate gyrus of both cerebral hemispheres were significantly decreased in DAT patients compared to normal controls. In conclusion, SPM analysis of SPECT images proved to be useful in the evaluation of abnormal perfusion areas of demented patients.

The existence of dopamine D2 receptors in the pituitary adenoma is an important factor for bromocriptine therapy. In order to evaluate the D2 receptors in the pituitary adenoma, 11C-N-methylspiperone (NMSP) and positron emission tomography was performed in a variety of pituitary adenomas other than prolactinoma. Eight patients with pituitary adenoma including four non-functioning adenomas, two growth hormone (GH) secreting adenomas, one ACTH secreting adenoma and one TSH secreting adenoma and ten normal healthy volunteers were examined. 740 MBq of 11C-NMSP was injected and dynamic scan was performed from the time of injection to 80 min postinjection. The time dependent regional radioactivity in the striatum (st) and in the tumor tissue (tm) was measured and the binding rate, alpha, was calculated according to the following equation: Cst, tm/Ccbl = alpha x integral of t0 Ccbl dt/Ccbl + 1. The ratio of total radioactivity in the striatum or tumor over total activity in the cerebellum was plotted versus "normalized time", which was obtained by dividing integrated cerebellar radioactivity by actual cerebellar radioactivity for each timepoint. In three patients with pituitary adenoma, two scans were performed before and three hours after oral intake of 2.5 mg of bromocriptine. The alpha values for pituitary adenoma and normal striatum were 0.031 +/- 0.023 (0.017-0.088) and 0.042 +/- 0.006 (0.034-0.049), respectively. Bromocriptine reduced alpha value to various degree in pituitary adenoma (13-56%) but not in striatum (-3.7-3.3%). Our data suggests that in some of pituitary adenoma other than prolactinoma, dopamine D2 receptors existed but that nonspecific binding also contributed to the radioactivity in the tumor tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

The clinical usefulness of a new myocardial perfusion imaging agent, 99mTc-1,2-bis[bis(2-ethoxyethyl)phosphino]ethane (99mTc-Tetrofosmin, (PPN1011) was evaluated in 355 patients with various heart diseases. Both 1 and 2 day protocols resulted in images that were significantly clearer than those of 201Tl. The absence of significant drug related adverse reaction supported the safety of the agent for clinical use. Regional abnormalities detected by CAG agreed with 99mTc-Tetrofosmin SPECT findings in 74% and with 201Tl SPECT in 78% of this study. Eighty-four percent of an abnormalities were detected with 99mTc-Tetrofosmin SPECT, as compared with those detected with 201Tl SPECT (88.4%). The complete concordance ratio between 99mTc-Tetrofosmin and 201Tl images in segmental analysis was 87-89% at rest and stress. Since 99mTc-Tetrofosmin SPECT was judged clinically useful in 93.2% (331/355) of the patients studied, it is concluded that 99mTc-Tetrofosmin is a promising agent for myocardial perfusion imaging. The simple labeling procedure without heating and cooling is suitable for emergency administration. Reconditioning of myocardial perfusion could be evaluated with 99mTc-Tetrofosmin injection before and after interventional therapy. These are additional features of the agent for clinical use.

Since the application of positron emission computed tomography (PET) for myocardium, the evaluation of myocardial blood flow, glucose metabolism, fatty acid metabolism, oxygen consumption and etc. has been performed. Especially, it has been regarded very important clinically to evaluate myocardial viability from the mismatch of myocardial glucose metabolism and blood flow. Many early myocardial PET studies were qualitative, while recently noninvasive quantitation method without arterial blood sampling has become possible in quantitating myocardial glucose metabolism or myocardial blood flow reserve. We quantitated regional myocardial glucose utilization rates (rMGU) in 114 cases during fasting, oral glucose loading, or insulin clamp to study the relation between rMGU and plasma insulin value or FFA value, the normal rMGU value during each condition and the difference of rMGU among each part of myocardium. And as to the question in which condition of FDG study was appropriate to evaluate myocardial viability, we introduced the opinion of Schelbert for oral glucose loading or insulin injection method and presented our opinion for fasting or mild insulin clamp.

A new myocardial perfusion imaging agent, 99mTc-1,2-bis[bis(2-ethoxyethyl phosphino]ethane (99mTc-PPN1011) was administered to 52 patients with various heart diseases each at rest and peak exercise on different days (Method A) and on the same day (Method B). The safety, optimal dosage, imaging procedures and the clinical usefulness were evaluated. No drug related adverse reactions were found. Image quality was considered adequate for diagnosis with as little as 185 MBq per injection, though the optimal dose range was 370-740 MBq. SPECT images were obtainable as early as 10 min, also until 3 hours after injection. There were no significant differences in clinical efficacy between method A and B, as well as sequential tests at rest and exercise. 99mTc-PPN1011 and 201T1 images in the same patient were compared segment by segment. Image quality of 99mTc-PPN1011 was significantly superior to that of 201T1. Analysis of images indicated that both agent were similar in diagnostic efficacy. It was concluded that 99mTc-PPN1011 is useful for myocardial perfusion imaging.

In order to evaluate glucose metabolism in brain death, 18F-FDG-PET scans were performed in three patients with clinically highly suspected brain death. One case was caused by head trauma and other two cases were by subarachnoid hemorrhage. All of them were in deep coma without spontaneous breathing, whose intracranial pressure was remarkably elevated up to the level of mean arterial pressure. Nineteen frames of dynamic scan were started soon after intravenous injection of 18F-FDG for one minute per frame, followed by 10 minutes of static scan which started 40 minutes after the injection. Both in dynamic and static scan, no significant intracranial accumulation of 18F-FDG was seen in all of three cases. This finding can be interpreted as the evidence that there is no significant glucose utilization from blood in the brain. This is the first report of clinical application of 18F-FDG-PET to brain death. Our results support the clinical diagnosis of brain death and 18F-FDG-PET can be of value for the assessment of glucose metabolism in patients with suspected brain death.

Metabolism of 99mTc-ethyl cysteinate dimer (99mTc-ECD) in blood was studied mainly in vitro. When 99mTc-ECD was mixed with blood taken from 12 subjects, the octanol extraction ratio of ECD (y) decreased rapidly and the octanol extraction ratio-time profile well fitted a monoexponential curve (y = Ae-kt/1000, A, k: constant, t: time after mixing). The k value and hematocrit (Ht) were significantly correlated (k = 0.376Ht-3.27, r = 0.897, p less than 0.001), therefore, it was suggested that the majority of the enzyme which dissolves ECD exists in red blood cells. When ECD was mixed with blood, there were more hydrophilic products of ECD in plasma than those generated by the enzyme in plasma. In vivo input function of 99mTc-ECD was calculated by arterial blood sampling and octanol extraction. The duration of effective input was relatively short, which was attributed to rapid decrease of octanol extraction ratio in vivo.

Intra-arterial infusion liver scintigraphy was performed in 11 patients with primary or metastatic liver tumor, and intraportal infusion liver scintigraphy was performed in 6 patients for prophylaxis of liver metastasis from colorectal cancer. 99mTc-Sn colloid or 99mTc-phytate was administered through the catheter of which tip was placed in the portal vein or the hepatic artery, and then liver image was obtained. When 99mTc-phytate was infused intra-arterially, significant amount of the infused tracer passed through the liver and we could not get sufficient information to assess the distribution of drug administered through the catheter. On the other hand, intraportal infusion liver scintigraphy using 99mTc-Sn colloid or 99mTc-phytate and intra-arterial infusion liver scintigraphy using 99mTc-Sn colloid revealed heterogeneity of liver uptake, tracer uptake in spleen, low uptake area corresponding to the liver tumor and high uptake area around it. The findings will be clinically useful, and these methods are thought to be helpful to confirm the satisfactory drug distribution.

We discuss three cases irradiated to their bone metastases. 99mTc-MDP bone scan before irradiation showed normal uptake in the lesions. In all the cases, the irradiation therapy was effective, but focal increased uptake area corresponding to the site of bone metastasis was revealed by the follow-up bone scan one to three months after irradiation. We concluded that the change of tracer uptake was so-called flare in formerly false negative lesion. The cause of this phenomenon was considered either elevation of osteoblastic activity with control of tumor or progression of osteolysis until tumor got well-controlled.

99mTc-SQ30217 555 MBq (15 mCi) was intravenously injected to 6 healthy subjects to study its safety, pharmacokinetics and the imaging time. Neither side effects nor abnormalities in physical findings, hemato-biochemical tests, urinary test, etc. caused by this agent were observed in any case and its safety was suggested. Radiation dose estimates over the entire body was 4.88 mGy/1,110 MBq (0.488 rad) and that over the major organs was less than 10 mGy and they were within the allowable ranges. 99mTc-SQ30217 showed biphasic disappearance curve in blood with the half-life of alpha-phase 0.02 hour and that of beta-phase 10.14 hours. 99mTc-SQ30217 was considered to show characteristic pharmacokinetics in that the myocardial accumulation was high in an early stage of the administration, but it rapidly decreased. Both heart to liver ratio and heart to lung ratio were high within 10 minutes, but they decreased after 15 minutes. As a result of SPECT imaging of 4 patients with ischemic cardiac disease, the images obtained with 99mTc-SQ30217 at an early period after the administration was as good as those with 201Tl and the appearance of defects in the images with both agents was similar. 99mTc-SQ30217 was considered to be sufficiently useful as a 99mTc-labelled agent for myocardial blood flow.

Eighteen patients with Alzheimer's disease (AD), 5 patients with Pick disease (PD), 6 patients with other types of degenerative dementia (O) and 12 age-matched normal control subjects (N) were studied using N-isopropyl p-[I-123]iodoamphetamine (I-123 IMP) with SPECT. Regional to cerebellar activity (R/CE) ratio and frontal to parietal (F/P) activity ratio were evaluated in each case. I-123 IMP-SPECT revealed focal abnormality in all cases in AD, PD, O group, while XCT and/or MRI were normal or showed cerebral atrophy without focal abnormal density or intensity. In AD group, R/CE ratio in all the regions except for bilateral Rolandic area and left primary visual cortex were significantly lower (p less than 0.05 or p less than 0.01) than that in N group, and F/P ratio were significantly higher (p less than 0.01) than that in P and O group. In conclusion, I-123 IMP-SPECT is useful to detect focal perfusion abnormality in dementia and may be of value in differentiating Alzheimer's disease from dementia of non-Alzheimer type.

To assess the cardiac response to various exercise in ischemic heart disease (IHD), left ventricular function was continuously measured with an ambulatory ventricular monitor (VEST) in 3 normal subjects and 15 IHD patients. Treadmill exercise (early stage (E1), end stage (E2) and recovery standing state (RE], walking (WK) and climbing stairs (CS), was used for exercise. 15 IHD patients were divided into 4 groups by the LVEF response to treadmill exercise. In group 1 (G1), LVEF increased gradually at stage 1 and became plateau from stage 2 to end stage like normal group. In group 2 (G2), LVEF increased at stage 1 and became plateau from stage 2 but decreased from maximal EF more than 5% at end stage. In group 3 (G3), LVEF increased only at stage 1 and decreased immediately after stage 1 to end stage. The decrease of LVEF at end stage from standing was more than 5%. In group 4 (G4), LVEF decreased at stage 1 and became minimum at end stage. This grouping was well related to thallium redistribution (Tl RD) score and coronary arteriography (CAG) score. We could predict the severity of coronary artery disease from this grouping because all group 3 or 4 patients had severe coronary artery disease. VEST was useful for the evaluation for the tolerance to daily activities. Group 1, 2 and 3 tolerated daily activities while group 4 could not always. The degree of the increase in cardiac output during ischemia evaluated by VEST may be one of the useful index of the tolerance to exercise. In conclusion VEST was very useful for evaluating cardiac capacity of ischemic heart disease patients during various exercise.