Spin‐spin relaxation of brain tissues in systemic lupus erythematosus

Abstract

Objective. To correlate the spin-spin relaxation time (T2) of brain tissue in neuropsychiatric systemic lupus erythematosus (NPSLE) with the patient's clinical condition.Methods. T2 values were determined in 54 SLE patients and 45 non-SLE cointrols at 1.5 Tesla, using intensity from multi-echo magnetic resonance (MR) images fitted to an exponential decay curve with rateconstant T2.Results. The T2 of white matter was increased in SLE patients compared with controls (P = 0.01) and was increased in those patients who had previously experienced major NPSLE. Conclusion. Quantitative T2 measurement extends the utility and sensitivity of conventional MR imaging for evaluating NPSLE.Magnetic resonance imaging (MRI) has had an increasing role in the evaluation of neuropsychiatric (NP) symptoms associated with systemic lupus erythematosus (SLE) (1-10). MRI can detect the typical pathology of NPSLE, including focal and diffuse hyperintense lesions, infarcts, hemorrhage, and atrophy, with greater sensitivity than computed tomography (2,9). Although MRI provides excellent anatomic detail, interpretation is limited by the experience and objectivity of the observer, the discriminative ability of the human eye, and the inherent image contrast. MRI can provide quantitative data regarding the relaxation properties of water in different chemical environments induced by inflammatory diseases of the brain (1 1). Spin-lattice relaxation time (TI) and spin-spin relaxation time (T2) provide information regarding the total water in brain, the compartmentalization of brain water, and the degree of association between this water and macromolecules such as myelin and protein (12). The total quantity of water (proton density), T1, and T2 are responsible for the image intensity in both normal and abnormal tissues.Pathologic processes, including edema, infarction, and inflammation, usually increase both T2 and proton density. T2 values have been reported to be elevated in normal-appearing white matter of SLE patients and other patients with inflammatory brain disease (13). The current study determined the T2 values of cerebral lesions and normal-appearing brain

Automated T2 quantitation in neuropsychiatric lupus erythematosus: A marker of active disease

“…All patients received careful neurological and rheumatological examinations. Patients were classified as major or minor NPSLE based on the method of Carbotte et al (8,(17)(18)(19). Some patients with minor symptoms had previously suffered major episodes that had resolved at the study time.…”

“…Eighty individual volume measurements were taken in normalappearing frontal GM, and mean (trimmed mean) T 2 values were calculated for each patient using a 10% trimming process to reduce further the probability of volume averaging with white matter (WM) or CSF (8). To minimize partial volume effects, volumes were selected away from apparent tissue borders and focal lesions.…”

“…T 2 values for normal-appearing GM were calculated using a highly reproducible two-point determination from the axial images as described previously (8,14,20). Volumes of 4 ϫ 4 ϫ 5 mm were selected in GM by the operator.…”

“…We have reported that increased gray matter (GM) spin-spin relaxation time (T 2 ) is a marker of active NPSLE associated with major neurologic presentations-generalized seizures, psychosis, delirium, or coma (8). In that study, the increase in GM T 2 was not discernable by conventional radiological interpretation, but instead required quantitative T 2 analysis to demonstrate abnormalities in these normal-appearing tissues on MRI.…”

Abstracts (Continue in Part VII)

“…Using magnetic resonance spectroscopy (H-MRS) we have reported that normal-appearing brain tissue in previously active NPSLE is characterized by the loss of the neuronal marker N-acetylaspartic acid (NAA) and the presence of cerebral atrophy, findings indicative of diffuse neuronal loss due to a potent neurotoxic process and the observation of increased lactate/lipid in NPSLE patients (Sibbitt 1993). More recently, using Sl data we have reported reduced NAA in focal lesions in NPSLE (Brooks, 1995). This study serves to expand on these previous findings by investigating the neuroiiietabolic status of NPSLE patients with active, major neurological dysfunction versus minor neurological dysfunction and address the issue of enhanced lactate using both short and long echo spectroscopy.…”