The regulatory mechanism of bipedal standing in humans remains to be elucidated. We investigated neural substrates for maintaining standing postures in humans using PET with our mobile gantry PET system. Normal volunteers were instructed to adopt several postures: supine with eyes open toward a target; standing with feet together and eyes open or eyes closed; and standing on one foot or with two feet in a tandem relationship with eyes open toward the target. Compared with the supine posture, standing with feet together activated the cerebellar anterior lobe and the right visual cortex (Brodmann area 18/19), and standing on one foot increased cerebral blood flow in the cerebellar anterior vermis and the posterior lobe lateral cortex ipsilateral to the weight-bearing side. Standing in tandem was accompanied by activation within the visual association cortex, the anterior and posterior vermis as well as within the midbrain. Standing with eyes closed activated the prefrontal cortex (Brodmann area 8/9). Our findings confirmed that the cerebellar vermis efferent system plays an important role in maintenance of standing posture and suggested that the visual association cortex may subserve regulating postural equilibrium while standing.

This study was designed to assess the value of whole-body positron emission tomography (PET) using 2-[fluorine-18]-fluoro-2-deoxy- D-glucose (FDG) for the diagnosis of recurrent ovarian cancer. Twenty-five patients who had previously undergone surgery for ovarian cancer were imaged using whole-body FDG-PET. During the 4 weeks preceding the PET study, conventional imaging, comprising computed tomography (CT) and magnetic resonance (MR) imaging of the abdomen and/or pelvis, was performed and serum CA125 levels were measured. PET imaging was commenced at 60 min after the intravenous administration of FDG in all patients. PET results were compared with the results of conventional imaging and CA125 levels, and related to pathological findings and clinical follow-up for more than 6 months. FDG-PET showed a sensitivity of 80% (16/20), a specificity of 100% (5/5) and an accuracy of 84% accuracy (21/25) for the diagnosis of recurrent ovarian cancer. The sensitivity, specificity and accuracy of conventional imaging were 55% (11/20), 100% (5/5) and 64% (16/25), respectively. PET could detect recurrent lesions in seven of nine patients in whom conventional imaging was falsely normal, while conventional imaging was true positive in two of four patients with false-negative PET results. The CA125 results showed a sensitivity of 75% (15/20), a specificity of 100% (5/5) and an accuracy of 80% accuracy (20/25). Among the 15 patients with true-positive CA125 results, PET correctly detected abnormal foci of recurrence in 13 patients (86.7%) whereas conventional imaging showed recurrent lesions in only eight patients (53.3%). In conclusion, our preliminary study demonstrates that FDG-PET may be accurate and useful for the detection of tumour recurrence when conventional imaging is inconclusive or negative, especially in patients with abnormal CA125 levels.

Hippocampal head dysfunction plays an important role in memory impairment in amnesic patients. Further metabolic impairment over the amygdalohippocampal system and the surrounding association cortex reflects the pathophysiology of AD.

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