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Acute hypoxic pulmonary vasoconstriction has an established role in the preservation of ventilation-perfusion balance. To further characterize this homeostatic response in man we have attempted to measure both the time course and magnitude of blood flow diversion from single hypoxic lobes. Lobar hypoxia (mean PO2 38 +/- 1.5(SEM)mmHg, mean PCO2 39.9 +/- 0.9(More)
Recent research has shown that some patients with schizophrenia have a severe impairment in the suppression of reflexive saccadic eye movements in the ANTI-saccade task. This saccadic distractibility has previously been found in patients with lesions of dorsolateral prefrontal cortex, implicating an abnormality of prefrontal cortex. The objective of the(More)
INTRODUCTION We present a method of automatic classification of I-fluoropropyl-carbomethoxy-3β-4-iodophenyltropane (FP-CIT) images. This technique uses singular value decomposition (SVD) to reduce a training set of patient image data into vectors in feature space (D space). The automatic classification techniques use the distribution of the training data in(More)
Criteria used to place ventilation-perfusion lung scans into categories with different probabilities for pulmonary embolism depend largely on the size and anatomical distribution of defects recognized. These criteria assume that actual segmental defects appear segmental on the lung scan. This study examined the accuracy with which four experienced observers(More)
A method is proposed for automatic analysis of dynamic radionuclide studies using the mathematical technique of principal-components factor analysis. This method is considered as a possible alternative to the conventional manual regions-of-interest method widely used. The method emphasises the importance of introducing a priori information into the analysis(More)
BACKGROUND AND AIM Selective internal radiation therapy with 90Y microspheres (SIR spheres) is increasingly used in the treatment of extensive liver tumours. Careful selection and preparation of patients are necessary to avoid possible adverse effects. We aimed to evaluate the incidence and severity of adverse effects resulting from the administration of(More)
UNLABELLED PET is an important functional imaging technique that can be used to investigate neurotransmitter receptors and transporters directly by mapping human brain function. PET is increasingly being used greatly to advance our understanding of the neurobiology and pathophysiology of schizophrenia. METHODS This review focuses on the use of PET tracers(More)
Gastric emptying may be delayed in HIV infection. We aimed to characterize the pattern of gastric emptying in HIV seropositive subjects and correlate the findings with symptoms, as well as to identify possible etiological factors. Solid gastric emptying was measured using scintigraphy in 54 HIV seropositive subjects and 12 HIV seronegative controls.(More)
An appreciation of the appearances of segmental and lobar defects on a lung scan is important for the diagnosis of pulmonary embolism. The appearances of segmental and lobar ventilation defects of known anatomical location have been examined on 81mKr ventilation scans in normal human subjects, utilizing fibreoptic bronchoscopy to place temporary occlusions(More)
Positron emission tomography (PET) offers a strategic imaging platform to provide a map of functional neural correlates associated with the underlying cognitive deficits in schizophrenia. It enables regional cerebral glucose metabolism and dopaminergic and serotonergic receptor function to be studied. PET neuroimaging can therefore be used in drug(More)