Magnetic resonance spectroscopy in the evaluation of central nervous system manifestations of systemic lupus erythematosus

Abstract

Neuropsychiatric (NP) systemic lupus erythematosus (SLE) is characterized by a large spectrum of physical and behavioral manifestations. One major difficulty is the absence of diagnostic tools for assessing disease activity and severity of NP manifestation. The neurologic symptoms can be of new onset, chronic, or of a former or resolved nature (1). Although several studies have used different neuroimaging tools, including computed tomography, magnetic resonance imaging (MRI), and single-photon– emission computed tomography, no single technique has proven to be definitive for diagnosis of NP manifestations in persons with SLE (1). Magnetic resonance spectroscopy (MRS) permits chemically specific, noninvasive measurements of some compounds of biologic importance in living tissues. MRS was discovered in 1946, but was only first used in living animal brain in 1980 (2), followed by use in human brains in several pathologies. In the human brain, phosphate energy stores, intracellular pH, lactate concentrations, and the neuronal marker N-acetylaspartate are examples of MRSmeasurable variables (3). The purpose of this article is to review studies using MRS in SLE and to discuss the clinical utility of this technique in determining central nervous system (CNS) involvement in individuals with SLE. We will also discuss future applications of MRS in the evaluation and treatment of NP manifestations in patients with SLE. History The nuclear magnetic resonance (NMR) phenomenon was discovered independently in 2 laboratories in 1946 by Bloch and Purcell, which led them to receive the Nobel Prize for physics in 1952. When imaging methods using the NMR signal were first developed, the term NMR imaging had been applied. But because of increasing danger of nuclear energy in the 1980s and because MR techniques do not use ionizing radiation, the term nuclear was dropped in clinical use, being maintained only to describe the physical phenomenon itself (3).