title: Comparison of MR relaxation times and X-ray attenuation coefficients of focal brain lesions.
abstract: Twenty cases of selected focal brain parenchymal lesions that were seen on both X-ray CT and magnetic resonance (MR) imaging were studied retrospectively. The CT attenuation coefficients and MR relaxation times were calculated for each lesion in an attempt to determine if an interdependence existed between these parameters. The CT attenuation and spin-lattice relaxation time (T1) appeared to be independent. There appeared to be an inverse relationship between CT attenuation and spin-spin relaxation time (T2). It is suggested that the explanation of this relationship is that lesions with greater amounts of edema tend to have lower CT attenuations and longer T2s and that this effect plays a major role in determining these values. The reason that T1 does not show a similar relationship is unknown. It is suggested that the explanation may be a combination of more complex factors determining T1 and of small sample size.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging; D001932:Brain Neoplasms / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed