Ryo Takeuchi

Usefulness of a three-dimensional stereotaxic ROI template on anatomically standardised 99mTc-ECD SPET

Abstract. We have constructed a three-dimensional stereotaxic ROI template (3DSRT) on anatomically standardised cerebral blood flow (CBF) single-photon emission tomography (SPET) images to objectively estimate regional CBF (rCBF). The 3DSRT is composed of 259 regions of interest (ROIs) in 11 segments (1, superior frontal; 2, middle and inferior frontal; 3, primary sensorimotor; 4, parietal; 5, angular; 6, temporal; 7, occipital; 8, pericallosal; 9, lenticular nucleus; 10, thalamus; 11, hippocampus) on each side. We measured the rCBF values of the 518 ROIs and calculated the area-weighted average (segmental CBF; sCBF) of the 22 segments based on the rCBF in each ROI. We compared vascular reserve before and after revascularisation surgery using sCBF on anatomically standardised resting and acetazolamide (Acz)-challenged CBF SPET images, which were obtained using an equal-volume-split dual-injection single-day protocol [resting and vascular reserve (RVR) method] in 13 patients who had not suffered any major stroke but did have significant cerebrovascular stenosis. Prior to the evaluation, we examined the sCBF values of 16 subjects with various cerebrovascular conditions (8, normal; 3, lacunar infarction; 2, chronic infarction; 2, meningioma; 1, aneurysm) using physiological saline instead of Acz (placebo study) in order to confirm the reproducibility of the RVR method. In the placebo study we observed excellent linearity (y=1.444+0.964x) between the 352 pairs of baseline (x) and post-placebo (y) sCBF values in the 16 subjects, irrespective of the segment location. In all of the 13 patients, estimation of sCBF demonstrated impaired vascular reserve pre-operatively and improved vascular reserve postoperatively. We conclude that the 3DSRT, which could be identically set on the anatomically standardised images obtained at baseline and after Acz injection, allowed objective assessment of the pre- and postoperative vascular reserve, which was not easy with conventional ROI settings. While 3DSRT appeared useful for the evaluation of regional vascular reserve as well as rCBF, further study is necessary to clarify its general clinical value.

Cerebral blood flow SPET in transient global amnesia with automated ROI analysis by 3DSRT

The aim of this study was to determine the areas involved in episodes of transient global amnesia (TGA) by calculation of cerebral blood flow (CBF) using 3DSRT, fully automated ROI analysis software which we recently developed. Technetium-99m l,l-ethyl cysteinate dimer single-photon emission tomography (99mTc-ECD SPET) was performed during and after TGA attacks on eight patients (four men and four women; mean study interval, 34 days). The SPET images were anatomically standardized using SPM99 followed by quantification of 318 constant ROIs, grouped into 12 segments (callosomarginal, precentral, central, parietal, angular, temporal, posterior cerebral, pericallosal, lenticular nucleus, thalamus, hippocampus and cerebellum), in each hemisphere to calculate segmental CBF (sCBF) as the area-weighted mean value for each of the respective 12 segments based on the regional CBF in each ROI. Correlation of the intra- and post-episodic sCBF of each of the 12 segments of the eight patients was estimated by scatter-plot graphical analysis and Pearson’s correlation test with Fisher’s Z-transformation. For the control, 99mTc-ECD SPET was performed on eight subjects (three men and five women) and repeated within 1 month; the correlation between the first and second sCBF values of each of the 12 segments was evaluated in the same way as for patients with TGA. Excellent reproducibility between the two sCBF values was found in all 12 segments of the control subjects. However, a significant correlation between intra- and post-episodic sCBF was not shown in the thalamus or angular segments of TGA patients. The present study was preliminary, but at least suggested that thalamus and angular regions are closely involved in the symptoms of TGA.

Noninvasive Quantitative Measurements of Regional Cerebral Blood Flow Using Technetium-99m-L,L-ECD SPECT Activated With Acetazolamide: Quantification Analysis by Equal-Volume-Split 99mTc-ECD Consecutive SPECT Method

Resting- and acetazolamide (Acz)-activated-regional cerebral blood flow (rCBF) measurements were performed by consecutive single-photon emission computed tomography (SPECT) studies before and after Acz administration using equal-volume-split technetium-99m-L,L-ethyl cysteinate dimer. Quantitative rCBF images were converted from qualitative axial SPECT images by the application of Patlak plot graphical analysis with radionuclide angiography and Lassens linearization correction. Total time span required for this study was 53 minutes. The unaffected side of 37 studies with unilateral vascular lesions and 45 studies without apparent vascular lesions showed 132 ± 17% and 140 ± 15% increase of mean CBF (mCBF), respectively, under Acz administration. Comparing these values, the Acz-activated rCBF increases of less-affected and affected hemispheres of 23 studies with bilateral vascular lesions (116 ± 13% and 113 ± 12%, respectively) was lower with high statistical significance (P < 0.001). For the other 20 cases, physiologic saline was administered instead of Acz. This group showed no changes in mCBF under placebo administration (after placebo/baseline; 100 ± 6%). Acetazolamide-activated rCBF increase was recognized clearly and easily using quantitative images. This noninvasive method is easy to perform and may be helpful to detect regional abnormalities of hemodynamic reserve in cerebrovascular diseases.

Platinum complex catalyzed synthesis of urea derivatives from nitroarenes and amines under carbon monoxide

Abstract N,N-Diarylureas were obtained in good yields from nitroarenes and aminoarenes at 140°C under carbon monoxide (initial 60 kg cm−2) in the presence of a catalytic amount of dichlorobis(triphenylphosphine)platinum(II), the yields of N,N′-diphenylurea, N,N′-bis(4-methylphenyl)urea, and N,N′-bis(4-chlorophenyl)urea were 65, 67 and 61%, respectively. Benzimidazole derivatives were obtained by the intramolecular cyclization reaction. An attempted synthesis of unsymmetric ureas resulted in the formation of a mixture of symmetric and unsymmetric products.

Acute Hepatic Failure following Transcatheter Arterial Embolization for the Treatment of Hepatocellular Carcinoma

We conducted a retrospective analysis to evaluate the risk factors associated with the occurrence of acute hepatic failure following transcatheter arterial embolization (TAE) for hepatocellular carcinoma. From 1984 to 1993 we performed a total of 623 embolization procedures in 369 patients with both hepatocellular carcinoma and chronic liver disease. Within 2 weeks after TAE, 13 patients (2.1%) experienced hepatic failure as characterized by a rapid increase in serum bilirubin levels and the development of hepatic encephalopathy of grade 2 or higher. These results indicated that the following are risk factors for acute hepatic failure after TAE: poor hepatic functional reserve; high-dose infusion of chemotherapeutic agents, and a history of multiple embolization procedures.

The platinum catalyzed reduction of nitroarenes to aminoarenes with carbon monoxide and water

Abstract Nitroarenes were readily transformed to aminoarenes in excellent yields under mild conditions with carbon monoxide and water in the presence of a platinum catalyst. Triethylamine, SnCl 4 and PPh 3 are essential for the high catalytic activity. Nitroarenes are reduced chemoselectively by this procedure.

Hydrosilation of olefins with monosilane catalyzed by transition metal complexes

Hydrosilylation of 1-hexene and 1,5-hexadiene with SiH4 in the presence of transition metal or its compound as catalyst produced alkylated silanes.

Transient thyrotoxicosis in a patient with a functioning nodule; a possible occurrence of silent thyroiditis.

A 48-year-old woman with diffuse goiter presented with typical symptoms and signs of thyrotoxicosis. Thyroid scanning with I-123 revealed a localized accumulation of the radionuclide in the left lobe which corresponded to a small nodule later detected by ultrasonography, with suppression of the remaining tissues. Owing to the overall reduced radioactivity in the thyroid, she was suspected of having silent thyroiditis causing thyrotoxicosis. Meanwhile, the thyrotoxicosis subsided concurrently with an increase in radioactivity in the extranodular area that had initially been suppressed. The histology of thyroid tissues obtained at the time of operation revealed follicular adenoma or hyperplasia in the area of the localized I-123 uptake and findings similar to those in Hashimoto’s thyroiditis in the remaining tissues, supporting our clinical diagnosis of silent thyroiditis together with a functioning nodule.

Ga-67 citrate accumulation in adenomatous goiter

An elderly woman with a diffusely enlarged goiter and multiple miliary nodular lesions on chest x-ray showed Ga-67 accumulation in the right thyroid lobe. Histologic findings obtained after total thyroidectomy and open lung biopsy revealed papillary carcinoma in the left lobe with pulmonary metastases and adenomatous nodules in the right lobe. This is the first report of Ga-67 accumulation in adenomatous goiter.

Polycarbosilanes Prepared by the Polymerizations of Vinylsilane.

ビニルシラン (CH2=CH-SiH3) の重合を, (1) ラジカル重合用触媒, (2) アニオン重合用触媒, および (3) 配位アニオン重合用触媒 (Ziegler-Natta触媒) を用いて行い, 得られたポリマーの構造解析とそれらの特性を調べた. 重合様式によって主鎖構造の異なる3種類のポリカルボシランが得られた. ラジカル重合では低分子量 (Mn500-1500) で無色透明の液状ポリマー [-CH2-CH (SiH3)-, -CH2-CH2SiH2-] が, またアニオン重合では構造の異なる液状ポリマー [-CH (CH3) -SiH2-, Mn500-1500] がそれぞれ高収率で得られた. 配位アニオン重合では白色固体で, 溶媒には不溶のポリマー[-CH2-CH (SiH3)-]が得られた. シリル基の特異的な反応性からそれぞれの重合機構を提案した. これらはSi-H結合を有する反応性のポリマーであるが, 空気中, 常温では安定である. また不活性ガス中, 高温で焼成することによって炭化ケイ素が得られた.