\s=b\ Objective.\p=m-\Todevelop quantitative methods for identifying cerebral anomalies on magnetic resonance images of subjects with language disorders and other learning disabilities. Design.\p=m-\Partially blinded comparison of subjects with dyslexia, unaffected relatives, and a control group balanced for age and socioeconomic status. Criterion standard: clinical diagnosis of dyslexia by physician or learning disabilities specialist on the basis of clinical assessment and family history.Settings.\p=m-\Hospitalpediatric neurology clinic and private reading clinic.Patients and Other Participants.\p=m-\Volunteers: individuals with dyslexia (seven male and two female, aged 15 to 65 years) from professional families; unaffected first-and second\x=req-\ degree relatives (four male and six female, aged 6 to 63 years) available in the geographical area; and controls (five male and seven female, aged 14 to 52 years).Interventions.\p=m-\Gradient echo three-dimensional scan in Seimens 1-Tesla Magnetom; 128 1.25-mm consecutive sagittal images.Main Outcome Measures.\p=m-\(1) Average length of the tem-poral (T) and parietal (P) banks of the planum temporale;(2) interhemispheric coefficients of asymmetry for T and P banks: Left-Right interhemispheric coefficients of asymmetry= (L-R)/[(L+R)/2];(3) intrahemispheric coefficients of asym-metry=(T-P)/[(T+P)/2]; and (4) qualitative assessment of gyral variants in the parietotemporal operculum.Results.\p=m-\All groups had left-sided asymmetry for the temporal bank and right-sided asymmetry for the parietal bank.The group with dyslexia had exaggerated asymmetries, owing to a significant shift of right planar tissue from the temporal to parietal bank. They also had a higher incidence of cerebral anomalies bilaterally (subjects with dyslexia, six of nine; relatives, two of 10; and controls, zero of 12).Conclusions.\p=m-\Quantitative assessment of high-resolution magnetic resonance images can reveal functionally relevant variations and anomalies in cerebral structure. Further refinement of these measurement techniques should improve the diagnosis, classification, and treatment of language disorders and other learning disabilities.Early investigators believed that neuroanatomical cor-
Adaptive histogram equalization (AHE) and intensity windowing have been compared using psychophysical observer studies. Experienced radiologists were shown clinical CT (computerized tomographic) images of the chest. Into some of the images, appropriate artificial lesions were introduced; the physicians were then shown the images processed with both AHE and intensity windowing. They were asked to assess the probability that a given image contained the artificial lesion, and their accuracy was measured. The results of these experiments show that for this particular diagnostic task, there was no significant difference in the ability of the two methods to depict luminance contrast; thus, further evaluation of AHE using controlled clinical trials is indicated.
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