[Visualization of epileptic lesions using single photon emission computed tomography (SPECT) with N-isopropyl-p-(123I) iodoamphetamine after intravenous loading of bemegride--report of a case]

Single photon emission computed tomography (SPECT) was performed 30 minutes and 4 hours after injection of 111 MBq (3 mCi) N-isopropyl-p-(123I) iodoamphetamine (IMP) which was injected 5 minutes after the completion of intravenous bemegride loading. A 31-year-old female with simple partial seizures evolving to complex partial seizures evolving to generalized tonic-clonic convulsive seizures with a history of hospitalization, suffering from low-grade fever, generalized convulsive seizures, and impaired consciousness at the age of 27 years was studied. Angiographic examinations, X-CT, MRI, CSF examinations, and interictal neurological examinations were normal. She suffered from clonic convulsions in her right shoulder and arm, and hallucinations and dysmnesia which were characteristic of temporal lobe epilepsy. More recently she suffered from impaired consciousness once or twice a month. While the controlled IMP-SPECT study was normal, the IMP-SPECT study examined after the activation by intravenous bemegride loading showed the pattern of a regional increased uptake of IMP in the epileptic lesions corresponding with the epileptic symptoms, and a surrounding border of decreased uptake which might be the inhibition of surrounding neuronal activity and metabolism. In conclusion, the bemegride loading IMP-SPECT study could be a potential diagnostic method in patients with seizures whose epileptic lesions were not determined by the conventional methods or in whom the surgical interventions were considered, by reason of its capability to demonstrate positively the epileptic lesions.

Application of Hilbert transform to radionuclide-gated cardiac studies: analysis of asynchronous emptying and filling in various heart diseases

Fourier phase analysis has generally been used to investigate asynchronous emptying and filling in various heart diseases. A potential limitation of this form of analysis is curve fitting error, since a truncated Fourier series may not adequately describe the shape of a time-volume curve (TVC) and thus may produce errors in indices calculated from the fit. To overcome this problem, we developed a new method using Hilbert transform. Using Hilbert transform, the instantaneous phase (IP) curve was calculated directly from the TVC obtained from multigated cardiac blood pool images. Four parameters [time to maximum IP [T(max)], time to 0 in IP[T(0)], time to minimum IP[T(min)], and time from 0 to minimum IP [T(min-0)]] were extracted from the IP curves for each pixel, and functional images were constructed in 40 patients with ischemic heart disease (IHD), 16 with hypertrophic cardiomyopathy (HCM), 3 with dilated cardiomyopathy (DCM), and 7 normal controls (N). The standard deviations (SD) of these parameters were then calculated for the left ventricle. In IHD patients with a left ventricle ejection fraction (LVEF) of less than 50% and in DCM, the SDs of all parameters were significantly higher than in group N. In IHD patients with an LVEF of greater than 50%, the SDs of T(min), T(0), and T(min-0) were significantly higher than in group N, but there was no significant difference in the SD of T(max). In HCM patients, the SDs of T(min) and T(min-0) were significantly higher than in group N, suggesting the presence of asynchronous filling. In conclusion, this method appears to be promising for the quantitative analysis of asynchronous emptying and filling in various heart diseases.

Studies on in vitro paraquat and diquat removal by activated carbon

The adsorption characteristics of paraquat and diquat onto activated carbon in vitro were discussed for the primary treatment of acute poisoning by accidental, suicidal or homicidal ingestion of paraquat containing herbicides. Paraquat was adsorbed onto activated carbon more abundantly and more rapidly in physiological saline solution than that in artificial gastric juice and distilled water. Most suitable solvent for paraquat removal by activated carbon was physiological saline solution (0.9% sodium chloride solution). No significant correlation was observed between the ability of paraquat removal and the properties of adsorbent. Paraquat was preferentially adsorbed onto activated carbon in the mixed solution. The adsorption abilities by activated carbon (the removal ratio, the amount adsorbed and the adsorption rate) for paraquat were larger than those for diquat, and it was enhanced by added sodium chloride and added magnesium sulfate. Enhancing effect for adsorption removal was proportional to the saline concentration. As addition of salts into carbon suspension enhanced the adsorption ability, it will contribute to the effective treatment of acute poisoning.

[Estimation of integral value of input function for the quantification of cerebral blood flow with 123I-IMP using one-point arterial blood sampling]

Cerebral blood flow (CBF) has been measured using a microsphere model with octanol-extracted radioactivity counts (integral value of input function). We developed a new method estimating the integral value of input function. First, we fitted the whole brain time-activity curves early after intravenous injection of N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) by the least-squares method. Second, we differentiated this equation. Third, we calibrated it using octanol-extracted radioactivity counts of the arterial blood sampled at 5 min. Finally, we integrated it. A significant correlation was found between the integral values obtained using a new method and those obtained using the continuous arterial blood sampling data (y = 1.048x-1206, r = 0.984). The errors between the CBF values obtained using a new method and those obtained using the 5-min continuous arterial blood sampling was 6.88 +/- 4.78%. Measurement of integral values of the input function using a new method with one-point arterial blood sampling is less invasive and convenient, and is not influenced by cardiopulmonary disease or smoking. Therefore, it would be useful for the routine measurement of CBF.

[A case of a gastric cancer patient with high serum pepsinogen levels at relapse]

A rare case of a 68-year-old female cancer patient with an extremely high serum level of pepsinogens (PG) at relapse is presented. She had stage 3 Borrmann 3 type gastric cancer which was a poorly differentiated adenocarcinoma. Her postoperative serum PG levels had been within normal limits (23.0 ng/ml for PG-I and 3.2 ng/ml for PG-II), but at the time of the peritoneal relapse they were 5,630 ng/ml and 3,380 ng/ml, respectively. After was chemotherapy initiated, her serum PG levels decreased in parallel with an improvement of her clinical status. Immunohistochemical examination with monoclonal antibodies revealed PG-I and PG-II production in the primary and the metastatic lesions.

Study on digestibility and energy availability of daily food intake by the Japanese. Part 2. Horse mackerel and milk

Four male Japanese students were fed a semisynthetic diet including rice and whole egg as protein for seven days (basal-diet period), and in the following seven days milk and then, for seven days, horse mackerel were added at the expense of part of the corn starch and sugar in the basal diet (test-diet period). Urine and feces were collected throughout all periods and the contents of protein, fat and energy in these extra were determined. The results obtained were as follows: 1) Digestibility of protein was 97.3 +/- 4.1% for milk and 96.8 +/- 2.8% for horse mackerel. 2) Digestibility of fat was 96.7 +/- 1.9% for milk and 98.6 +/- 2.6% for horse mackerel. 3) The ratio of the total available energy to intake energy (Net Energy Availability) was 92.5 +/- 2.9% for milk and 88.4 +/- 5.2% for horse mackerel.

Assessment of systolic thickening with thallium-201 ECG-gated single-photon emission computed tomography: a parameter for local left ventricular function

We measured left ventricular (LV) systolic thickening expressed as a systolic thickening ratio in 28 patients, using 201Tl ECG-gated SPECT. Five normals, 15 patients with prior myocardial infarction, 5 with hypertrophic cardiomyopathy, and 3 with dilated cardiomyopathy were studied. The systolic thickening ratio was calculated as [(end-systolic--end-diastolic pixel counts) divided by end-diastolic pixel counts], using the circumferential profile technique of both end-diastolic and end-systolic short axial images. Functional images of the systolic thickening ratio were also displayed with the "bull's-eye" method. The mean systolic thickening ratio thus calculated were as follows: normals, 0.53 +/- 0.05 (mean +/- 1 s.d.); non-transmural prior myocardial infarction, 0.33 +/- 0.09; transmural prior myocardial infarction, 0.14 +/- 0.05; hypertrophic cardiomyopathy in relatively nonhypertrophied areas, 0.56 +/- 0.11; hypertrophic cardiomyopathy in hypertrophied areas, 0.23 +/- 0.07; and dilated cardiomyopathy, 0.19 +/- 0.02. The systolic thickening ratio analysis by gated thallium SPECT offers a unique approach for assessing LV function.

Progressive loss of cortical acetylcholinesterase activity in association with cognitive decline in Alzheimer's disease: a positron emission tomography study

We measured brain acetylcholinesterase activity in 30 patients with Alzheimer's disease (AD) and 14 age-matched controls by positron emission tomography (PET) and using a carbon 11-labeled acetylcholine analogue. Seven AD patients had repeat PET scans. The k3 values were calculated as an index of acetylcholinesterase activity in a three-compartment analysis using the metabolite corrected arterial input function. Twenty-eight of the 30 AD patients (14 each in the early and late onset subgroups) were retained in the study so as to equalize the range and average severity of cognitive impairment within the early and late onset subgroups. The k3 values were significantly reduced in the neocortex, hippocampus, and amygdala in the early onset AD patients, although the k3 values were significantly reduced only in the temporoparietal cortex and amygdala in the late onset AD patients. In the longitudinal study, all 7 repeat AD patients showed further reduction of cortical k3 values in the second PET scans, with a mean interval of 2 years, suggesting a progressive loss of the ascending cholinergic system from the nucleus basalis of Meynert in AD. In 37 AD patients, there was a highly significant correlation between the cortical k3 values and Mini-Mental State Examination scores, supporting the cholinergic hypothesis in AD.

Uptakes and images of 38K in rabbit heart, kidney, and brain

The purpose of this study was to evaluate the kinetics and image quality of positron-emitting 38K (half-life, 7.6 min) and high-resolution small-animal PET in the heart, kidney, and brain of rabbits.

METHODS

Studies were performed with 18 closed-chest anesthetized rabbits at baseline and during infusions of adenosine (0.2 mg/kg/min) and propranolol (0.5-1.0 mg/kg intravenously) using high-resolution small-animal PET. 38K was injected intravenously and dynamic PET imaging of the heart, kidney, or brain was performed for 3 min. Colored microspheres were injected into the left ventricle to measure organ blood flow. Arterial blood was withdrawn directly from the femoral artery, and, after the animals were killed, 38K activities in each organ were measured directly with a well counter. Uptake of 38K was calculated by dividing the 38K activities in each organ by the integral of the input function. The extraction fraction of 38K was estimated by dividing the uptake of 38K in each organ by the organ blood flow, measured by microspheres.

RESULTS

The left ventricular myocardium and kidney were clearly visualized, but there was no visual 38K uptake in the brain. For the heart, kidney, and brain, respectively, average blood flow was 2.91 +/- 1.29, 5.49 +/- 0.71, and 0.57 +/- 0.11 mL/min/g, and the extraction fraction of 38K at baseline was 0.55 +/- 0.13, 0.48 +/- 0.13, and 0.022 +/- 0004. The Renkin-Crone model fit the relation between myocardial extraction and flow under a wide range of myocardial blood flow (r = 0.89).

CONCLUSION

38K is a suitable tracer for noninvasively showing the potassium kinetics of the heart, kidney, and brain by PET imaging.

A study of regional cerebral blood flow and hemodynamics in cerebrovascular diseases by selective continuous infusion of Kr-81m

A tomographic study of regional cerebral blood flow and hemodynamics was performed on 25 patients with cerebrovascular diseases by selective continuous infusion of krypton-81m (Kr-81m). Kr-81m single photon emission computed tomograms were superimposed on X-ray computed tomograms to assess topographically the perfusion of the entire brain. Study of cerebrovascular diseases using this method showed: (1) regional cerebral blood flow change; (2) perfusion distribution change; (3) the route by which blood reached the brain or the obstructed artery proximal to the circle of Willis; (4) development of a collateral system and its actual function; and (5) efficacy of surgical bypass after extracranial-intracranial anastomosis. This method is especially useful in hemodynamic assessment in patients with ischemic cerebrovascular disease.

[Clinical usefulness of 99mTc-ECD--a multicenter phase 3 study]

A phase 3 clinical study of a newly developed brain perfusion agent, 99mTc-L,L-ethyl cysteinate dimer (99mTc-ECD), was performed in 521 cases of cerebrovascular diseases and impairment of brain function to evaluate the safety, effectiveness and usefulness of the agent as a multi-center study involving 35 institutions in Japan. Out of 510 cases evaluated for the clinical usefulness, valuable information for clinical diagnosis was obtained in 486 cases (95.3%), and 444 cases (87.1%) were judged as "extremely useful" or "useful". Although the positive ratio of abnormalities detected by the agent was as same as that of 99mTc-hexamethylpropyleneamine oxime (99mTc-HM-PAO), the abnormal regions detected by the agent had tendency to be larger in size and to have higher contrast than those detected by 99mTc-HM-PAO. It is concluded that 99mTc-ECD is a safe and useful radiopharmaceutical as a brain perfusion agent for the diagnosis of cerebrovascular diseases and impairment of brain function.

Evaluation of preoperative positron emission tomography with computed tomography (PET-CT) for detecting lymph node metastasis in gynecologic carcinoma

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Background: To evaluate the sensitivety, specificity, and accuracy of PET-CT for detecting lymph node metastasis in gynecologic carcinoma. Methods: Between May 2007 to August 2008, 36 consecutive patients (pts) with cervical carcinoma, endometrial carcinoma and epithelial ovarian carcinoma were enrolled. All pts underwent PET-CT prior to the surgery of systematic pelvic and paraaortic lymphadenectomy. For pathological metastatic lymph nodes, the size of intranodal tumor deposits (maximum diameter of metastatic foci in each lymph node) were recorded. Results: The total number of pelvic lymph nodes (PLNs) plus paraaortic lymph nodes (PANs) removed was 2426. The median number of removed lymph nodes (LNs) was 67 each pts (range: 25 to 102). The number of involvement LNs was 79 (3.5%). The sensitivity, specificity and accuracy of preoperative PET-CT to detect LN metastasis were 24%, 99.9%, and 97.5%, respectively. The sensitivity of PLNs and PANs were 39.5% and 7.3%, respectively. The sensitivity of squamous cell carcinoma (SCC) were 35.7%, that of adenocarcinoma were 8.1%. FDG-PET detected 100% of intranodal tumor deposits > or =10 mm, whereas tumor deposits smaller than 5 mm were not detected. Conclusions: The results of our study revealed 76% underdiagnosis (overlooking) in evaluation of preoperative PET-CT in LN metastasis. Particularly, tumor deposits smaller than 5 mm were not detected at all. Using PET-CT for detecting small LN metastasis in gynecologic carcinoma may be unreliable so far. However we found that PLNs are comparatively easy to be detected than PANs, and SCC are comparatively easy to be detected than adenocarcinoma. The improved usability and application of PET-CT for detecting LN metastasis in gynecologic carcinoma have to keep researching constructively.

No significant financial relationships to disclose.

[The role of gallium-67 citrate scintigraphy in gastro-intestinal malignant lymphoma]

To evaluate the clinical usefulness of gallium-67 scintigraphy in the detection of the gastrointestinal (GI) non-Hodgkin's lymphoma (NHL) and in the assessment of the therapeutic effects, gallium-67 scintigraphy was reviewed on 24 cases (25 lesions; stomach in 20, ileum in 2, and terminal ileum and/or cecum in 3). Twenty-three out of the 25 lesions (92.0%) were detected by gallium-67 scintigraphy, while barium study could detect all of the 25 lesions. The sizes of the gallium-67 negative 2 lesions were the smallest of all (2.5 and 3.0 cm). The tumor size was considered to the most important factor in the detection by gallium-67 scintigraphy, while the histological classification and the location of the tumor were not related to its detectability. Findings in follow-up gallium-67 scintigraphy after therapy on 10 cases were correlated well with the therapeutic effects. These data suggest that gallium-67 scintigraphy is useful for the detection of GI involvement of NHL and for the assessment of therapeutic effects.