Demonstration of cerebral microemboli occurring during coronary artery bypass graft surgery using fluorescein angiography.

Coronary artery bypass graft surgery is associated with an unacceptably high incidence of neurological and neuropsychological complications (Breur et al., 1981; Smith, 1988). The main cause of cerebral dysfunction following this type of surgery is probably cerebral microembolism (Dutton et al., 1974; Taylor, 1986). The eye is an outgrowth of the brain and therefore is uniquely suitable for the study of cerebral microcirculation. Retinal fluorescein angiography has been employed during this surgical procedure to demonstrate the changes which occur in the cerebral microcirculation during operation.

Influence of oxygenator type on the prevalence and extent of microembolic retinal ischemia during cardiopulmonary bypass. Assessment by digital image analysis.

We have previously reported the occurrence of microembolic ischemia in the retina during cardiopulmonary bypass, as revealed by fluorescein angiography. This method has been extended by digital image analysis to include quantification of the extent of retinal ischemia and has been applied to a prospective comparative study of 64 patients undergoing elective coronary operations with either a bubble or a membrane oxygenator. Patients with diabetes or clinically evident cerebrovascular disease were excluded. Bypass procedures were standardized in all cases with pulsatile flow and a 40 microns arterial line filter (Pall EC Plus). Thirty patients had bypass with a bubble oxygenator (Harvey H1700) and 34 patients had bypass with a flat sheet membrane oxygenator (COBE CML). In each case retinal fluorescein angiograms were obtained preoperatively and 5 minutes before the end of bypass and were processed with a digital image analyzer (Context Vision GOP-302). Microembolic perfusion defects were identified by digital subtraction of preoperative and end-bypass angiograms and their total area was computed. Results. In the bubble oxygenator group retinal perfusion defects indicative of microembolism occurred in all 30 (100%) patients. In contrast, over half the patients in the membrane oxygenator group had normal retinal perfusion, and the prevalence of perfusion defects (44%; 70% confidence limits 34% to 54%) was significantly less than in the bubble group (p less than 0.001). In addition, those patients in the membrane group had significantly fewer lesions (median 0; 70% confidence limits 0 to 1) than patients in the bubble group (median 2; 70% confidence limits 2 to 2; p less than 0.001) and also had significantly smaller total areas of retinal ischemia (median 0 mm2; 70% confidence limits 0 to 0.16 mm2) than the bubble group (median 0.22 mm2; 70% confidence limits 0.21 to 0.27 mm2; p less than 0.001). There was no relationship between the extent of retinal ischemia and bypass time, arterial blood gas concentrations, volume of cardiotomy suction or donor blood returned to the pump, or recent medication with aspirin. Inferences. Digital image analysis of retinal fluorescein angiograms may provide a method of quantifying microembolic ischemia in the central nervous system during cardiopulmonary bypass. Flat sheet membrane oxygenation appears to provide significantly better protection against microembolic ischemia than bubble oxygenation.

Sperm morphology by image analysis compared with subjective assessment.

Human sperm heads were detected and tracked using semi-automatic image analysis. Six measurements of size and shape were computed from two samples of semen from each of 26 men. Subjective assessments of abnormal morphological forms were made on the same samples by two independent assessors. A formula for prediction of percentage abnormality was calculated from the results. The subjective assessment of abnormality was related primarily to the number of elongated heads and secondly to the number of small heads. Computed image processing provides an objective method for measurement of the morphological features of sperm.

Morphometry of spermatozoa using semiautomatic image analysis.

Human sperm heads were detected and tracked using semiautomatic image analysis. Measurements of size and shape on two specimens from each of 26 men showed that the major component of variability both within and between subjects was the number of small elongated sperm heads. Variability of the computed features between subjects was greater than that between samples from the same subject.

Lateral ventricular size in schizophrenia: relationship to the disease process and its clinical manifestations.

Using computed tomography, lateral ventricular size was studied in a sample of 112 institutionalized chronic schizophrenic patients (selected from 510 cases to investigate the correlates of the defect state and intellectual decline and the effects of insulin, electroconvulsive and neuroleptic treatment), and compared with matched groups of non-institutionalized schizophrenics, patients with first schizophrenic episodes, institutionalized and non-institutionalized patients with primary affective disorder, and neurotic out-patients. Age was significantly correlated (P less than 0.0002) with lateral ventricular size, but the institutionalized schizophrenic patients had significantly larger (P less than 0.025) lateral ventricles than the neurotics when age was taken into account. Ventricular enlargement was unrelated to past physical treatment (neuroleptics, insulin coma and electroconvulsive therapy). Within the group of institutionalized schizophrenic patients few correlates of ventricular enlargement were identified; thus in this population increased ventricular size was not clearly associated with the features of the defect state (negative symptoms and intellectual impairment). However, there was a curvilinear (inverted-U) relationship between intellectual function and ventricular size. Increased ventricular size was significantly related to absence of hallucinations, impairment of social behaviour, inactivity and the presence of abnormal involuntary movements. The findings confirm that structural brain changes do occur in chronic schizophrenia, but illustrate some of the difficulties in elucidating the clinical significance of ventricular enlargement. Lateral ventricular size is strongly age-related and the distribution in chronic schizophrenia is skewed and not bimodal; the relationship to particular features of the disease is complex and likely to emerge only in studies with a large sample size.

Reading chest radiographs for pneumoconiosis by computer.

Computer programs for measuring simple pneumoconiosis in radiographs are described and assessed. The 36 films studied had been read by 11 skilled human observers and a 'radiological score' of pneumoconiotic severity was therefore available for each film. The computer assigns to each square grid of side 3-6 mm a measure which reflects the unevenness of the density distribution in that grid. The 'computed score' is defined as the mean diversity over all relevant grids in both lung fields. On the set of 36 films the correlation between radiological score and computed score was 0-88. By contrast, the correlation between the score assigned by a single observer and the average of the scores assigned by the other 10 was in the range 0-95 to 0-98. The program can use the computed score to classify a film into one of the four major International Labour Office (ILO) U/C categories, the success rate of this process being 80% compared with those quoted by other workers in the range 45%-65%. If the films used in this study be typical, then the program described may form the basis of an automatic method for measuring pneumoconiosis in epidemiological work.