Prefrontal cortex dysfunction and depression in atypical parkinsonian syndromes.

Depressive symptoms are common in patients with neurodegenerative disorders. Imaging studies suggest that a disruption of frontal-subcortical pathways may underlie depression associated with basal ganglia disease. This pilot study tested the hypothesis that frontal dysfunction contributes to depression associated with multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). Depressed patients with MSA (n = 11), PSP (n = 9), and age-matched controls (n = 25) underwent measures of cerebral glucose metabolism applying positron emission tomography with (18)F-fluorodeoxyglucose. Regional metabolism in the patient groups was compared to the normal subjects using the voxel-based statistical parametric mapping. Depressive symptom severity (Hamilton Depression Rating) and degree of locomotor disability (Hoehn & Yahr) were assessed in the patient groups. The association between prefrontal metabolism and the occurrence of depressive symptoms and the degree of locomotor disability was investigated. When compared to controls, MSA patients revealed significant metabolic decreases in bilateral frontal, parietal, and cerebellar cortex and in the left putamen. In PSP patients, significant hypometabolism was demonstrated in bilateral frontal cortex, right thalamus, and midbrain. Depression severity but not the patients' functional condition was significantly associated with dorsolateral prefrontal glucose metabolism in both patient groups. The findings of this pilot study support the hypothesis that depressive symptoms in MSA and PSP are associated with prefrontal dysfunction.     

Imaging of activated microglia with PET and [11C]PK 11195 in corticobasal degeneration.

Positron emission tomography (PET) using [(11)C]PK 11195, a ligand for peripheral benzodiazepine receptor binding sites, offers the opportunity to image activated microglia in vivo. This tool may therefore be used to display the occurrence of microglial activation in the course of neurodegeneration. A patient with the clinical diagnosis of corticobasal degeneration (CBD) and left-sided symptoms was studied using fluorodeoxyglucose (FDG) and [(11)C]PK 11195 PET. We found a marked right hemispheric hypometabolism and asymmetric microglial activation in corresponding areas of the basal ganglia and right temporal and parietal cortex. [(11)C]PK 11195 PET suggests involvement of microglial activation in the pathogenesis of CBD.     

Effects of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin on the dopaminergic and cholinergic receptors as evaluated by positron emission tomography in the Rhesus monkey

Summary The effects of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP) on the central cholinergic and dopaminergic systems in the Rhesus monkey brain were investigated by positron emission tomography (PET) with the muscarinic cholinergic receptor ligands (N-[¹¹C]methyl-benztropine) and dopaminergic receptor ligands selective for D₁ D₂, and D₃ subtypes ([¹¹C]SCH23390, N-[¹¹C]methyl-spiperone, and (+)[¹¹C]UH232, respectively). None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP used significantly affected the regional cerebral blood flow (rCBF as determined by Raichle's H₂ ¹⁵O method), and 10 mg/kg of R-THBP had little effect on the regional cerebral metabolic rate of glucose (rCMRglc) in the Rhesus monkey brain, as assessed by the graphical [¹⁸F]fluoro-deoxyglucose method. The effect of R-THBP on the muscarinic cholinergic system was dose dependent; while 3 mg/kg of R-THBP did not significantly alter the uptake ratio of N-[¹¹C]methyl-benztropine in several brain regions to that in the cerebellum, 10 and 30 mg/kg of R-THBP significantly reduced the uptake ratio in the thalamus, as well as in the frontal and temporal cortices. None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP tested affected [¹¹C]SCH23390 (dopamine D₁ receptor) binding. However, the k3 value for N-[¹¹C]methyl-spiperone (dopamine D₂ receptor) binding, which represents the association rate × B_max value, was significantly decreased in the striatum. The uptake ratio of (+)[¹¹C]UH232 (dopamine D₃ receptor) in the striatum to that in the cerebellum was also decreased by administration of R-THBP (3 and 30 mg/kg i.v.). These findings suggest that R-THBP acts on dopamine D₂ and D₃ receptors selectively without markedly affecting dopamine D₁ receptor binding. Furthermore, the changes in cholinergic and dopamine D₂ and D₃ receptors in vivo can not be attributed to a change in rCBF but may depend on the action of R-THBP.Abbreviations R-THBP 6R-L-erythro-5,6,7,8-tetrahydrobiopterin - PET positron emission tomography - rCBF regional cerebral blood flow - rCMRglc regional cerebral metabolic rate of glucose     

Retrograde ejaculation

Failure of the normal ejaculatory mechanism may lead to retrograde ejaculation. This occurs most commonly as a result of transurethral prostatectomy, retroperitoneal lymph-node dissection and diabetic neuropathy. The diagnosis is based on the absence of sperm in the antegrade ejaculate and the presence of sperm in the post-masturbatory urine. If pharmacologic attempts to restore antegrade ejaculation fail, sperm recovery from the urine and intrauterine insemination are usually indicated. Surgical alternatives are discussed.     

多巴酚丁胺负荷及运动试验~(99m)Tc-MIBI心肌断层显像与冠状动脉造影的对比研究

比较６９例冠心病患者多巴酚丁胺负荷９９ｍＴｃ甲氧基异丁基异腈（ＭＩＢＩ）心肌断层显像与８２例运动试验９９ｍＴｃＭＩＢＩ心肌断层显像的结果，以探讨它们对冠心病的诊断价值。结果表明：以冠状动脉造影结果为标准，多巴酚丁胺负荷诊断冠心病的敏感性和特异性分别为９１２％和８００％，运动试验分别为８９４％和８２９％。多巴酚丁胺负荷检出冠状动脉病变的敏感性和特异性：左前降支为７８１％和９１３％，回旋支为６６７％和９８２％，右冠状动脉为１００％和８３７％；运动试验分别为７８３％和９１１％，６００％和９６８％，９０９％和８５０％，差异均无显著性（Ｐ＞００５）。提示两者结果相近，对于不能进行运动试验的病人，多巴酚丁胺试验是一种有价值的诊断冠心病的方法。     

国产4环／7层PET仪初试

对我国１９９６年研制成功的４环／７层ＰＥＴ仪（轴向视野８ｃｍ）进行试用。先进行模型试验和动物实验，然后对１例正常志愿者和７例患者进行１８Ｆ脱氧葡萄糖（ＦＤＧ）ＰＥＴ显像。静脉注射１８ＦＦＤＧ３７０ＭＢｑ后约１５小时显像，成人全身显像行１１个床位采集，约１５小时，心脑局部显像行２～３个床位采集，约半小时。直径１～３ｃｍ的阴模和阳模皆可显示。８例全身冠状和矢状断层影像清晰，正常志愿者（正常进食）可见脑和心肌显影，膀胱内放射性较多。２例恶性肿瘤患者的６处病变浓聚１８ＦＦＤＧ。２例恶性肿瘤患者手术和化疗后无复发征，显像阴性。２例良性病变处未见１８ＦＦＤＧ浓集。１例陈旧性心肌梗塞患者１８ＦＦＤＧ心肌断层显像与９９ｍＴｃ甲氧基异丁基异腈心肌血流灌注显像匹配良好。正常心肌显影与否受葡萄糖负荷的影响。８例脑皮质横断影像良好，基底节和丘脑影像有时尚欠清晰。初试结果表明，该ＰＥＴ仪相当于至今尚在国外广泛使用的８０年代中期４环／７层ＰＥＴ仪水平，但具有９０年代ＰＥＴ仪全身整体冠状和矢状断层显像的功能，可用于全身肿瘤显像、心肌活性判断和功能性癫痫灶术前定位，但仪器操作性能和软件功能尚需进一步完善。     

Comparison of the treadmill exercise score and single-photon emission computed tomographic thallium imaging in risk assessment

Background  

This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD)     

Myocardial metabolic imaging by means of fluorine-18 deoxyglucose/technetium-99m sestamibi dual-isotope single-photon emission tomography

The detection of preserved glucose uptake in hypoperfused dysfunctional myocardium by fluorine-18 deoxyglucose (FDG) positron emission tomography (PET) represents the method of choice in myocardial viability diagnostics. As the technique is not available for the majority of patients due to cost and the limited capacity of the PET centres, it was the aim of the present work to develop and test FDG single-photon emission tomography (SPET) with the means of conventional nuclear medicine. The perfusion marker sestamibi (MIBI) was used together with the metabolic tracer FDG in dual-isotope acquisition. A conventional SPET camera was equipped with a 511-keV collimator and designed to operate with simultaneous four-channel acquisition. In this way, the scatter of 18F into the technetium-99m energy window could be taken into account by a novel method of scatter correction. Thirty patients with regional wall motion abnormalities at rest were investigated. The results of visual wall motion analysis by contrast cine-ventriculography in nine segments/heart were compared with the results of quantitative scintigraphy. The scintigraphic patterns of MIBI and FDG tracer accumulation were defined as normal, matched defects and perfusion-metabolism mismatches. Spatial resolution of the system was satisfactory, with a full width at half maximum (FWHM) of 15.2 mm for ¹⁸F and 14.0 mm for ^99mTe, as measured by planar imaging in air at 5 cm distance from the collimator. Image quality allowed interpretation in all 30 patients. 88% of segments without relevant wall motion abnormalities presented normal scintigraphic results. Seventy-five akinetic segments showed mismatches in 27%, matched defects in 44% and normal perfusion in 29%. We conclude that FDG-MIBI dual-isotope SPET is technically feasible with the means of conventional nuclear medicine. Thus, the method is potentially available for widespread application in patient care and may represent an alternative to the ²⁰¹T1 reinjection technique.     

Detection of local recurrence of soft-tissue sarcoma with positron emission tomography using [18F]fluorodeoxyglucose

Background: It is often difficult to detect a local recurrence of soft-tissue sarcomas due to disturbance of the normal anatomy by previous surgery and radiotherapy. The aim of this study was to assess the value of positron emission tomography (PET) with [¹⁸F]fluoro-2-deoxy-d-glucose (FDG) for detecting local recurrences. Methods: In the period 1992–1995, 17 patients with proven or suspected local recurrence of soft-tissue sarcoma were examined using FDG-PET. Fifteen of these patients were ultimately proven to have a recurrence. Results: Recurrence was visualized in 14 patients (93%). Small tumors (maximum diameter 0.5 cm) were as easily visible as large lesions (maximum diameter 20 cm). In one patient the PET scan was positive, but the recurrence could not be proven histologically. Recurrence was proven 1 year later. A recurrent low-grade liposarcoma was not visualized. The two patients with benign lesions had a negative PET scan. The mean glucose metabolic rate was calculated to be 13.2 μmol/100 g/min (range 1.9–28.4). A correlation was found between the histological malignancy grade and the metabolic rate (p<0.05; Kruskal-Wallis). Conclusion: PET with FDG is a useful addition to the diagnostic armamentarium for detecting local recurrence of soft-tissue sarcomas and provides an indication of the malignancy grade of the recurrent lesion. Presented at the 47th Annual Meeting of The Society for Surgical Oncology, Houston, Texas, March 17–20, 1994.