PubMed Health⌕ Search

Biomedical subjects

J M Mathias

Publications and source records attributed to J M Mathias.

At least 19 recordsLinked to original sources
PubMed1999

Texture analysis of spinal cord pathology in multiple sclerosis.

Texture analysis was applied to MR images of the spinal cord in an attempt to quantify pathological changes that occur in multiple sclerosis (MS). Texture features quantify macroscopic lesions and also the microscopic abnormalities that may be undetectable using conventional measures of lesion volume and number. Significant differences in texture between normal controls and MS patients were seen. Texture differences were detected between normal controls and relapsing-remitting patients before detectable spinal cord atrophy. There was also significant correlation between texture and disability. The segmentation and texture analysis technique demonstrates intraobserver coefficients of variation ranging from 0. 6-8.2%. Texture analysis has potential as a tool for monitoring changes associated with the development of disability in patients with MS. Reproducibility and sensitivity must be improved to use the technique for serial monitoring in individuals. Magn Reson Med 42:929-935, 1999.

Adult↗
PubMed1999

System identification of closed-loop cardiovascular control mechanisms: diabetic autonomic neuropathy.

We applied cardiovascular system identification (CSI) to characterize closed-loop cardiovascular regulation in patients with diabetic autonomic neuropathy (DAN). The CSI method quantitatively analyzes beat-to-beat fluctuations in noninvasively measured heart rate, arterial blood pressure (ABP), and instantaneous lung volume (ILV) to characterize four physiological coupling mechanisms, two of which are autonomically mediated (the heart rate baroreflex and the coupling of respiration, measured in terms of ILV, to heart rate) and two of which are mechanically mediated (the coupling of ventricular contraction to the generation of the ABP wavelet and the coupling of respiration to ABP). We studied 37 control and 60 diabetic subjects who were classified as having minimal, moderate, or severe DAN on the basis of standard autonomic tests. The autonomically mediated couplings progressively decreased with increasing severity of DAN, whereas the mechanically mediated couplings were essentially unchanged. CSI identified differences between the minimal DAN and control groups, which were indistinguishable based on the standard autonomic tests. CSI may provide a powerful tool for assessing DAN.

Adult↗