ABSTRACT
We performed proton magnetic resonance imaging of the vitreous body in a 37-year-old mother and her 14-year-old son who suffered from autosomal dominant vitreoretinal dystrophy. Both showed the characteristic signs of the disease including premature liquefaction of the vitreous. Magnetic resonance imaging at 1.5 T using a standard head coil yielded a shortened mean (+/- SD) transverse proton relaxation time (T2) of the vitreous in our patients (T2 = 311 +/- 22 ms) in comparison with 8 eyes of normal volunteers (T2 = 546 +/- 157 ms). The longitudinal proton relaxation time (T1) showed a tendency towards lower values in the patients (T1 = 2,928 +/- 207 ms) but was not significantly decreased when compared with normal volunteers (T1 = 3,257 +/- 307 ms). The decrease in the T2 times in our patients is in accordance with previous in vitro studies of artificial vitreous liquefaction in bovine eyes and provides information on the mechanism of vitreous liquefaction in vitreoretinal dystrophy.
Subject(s)
Magnetic Resonance Imaging/methods , Retinal Degeneration/diagnosis , Retinal Degeneration/genetics , Vitreous Body/pathology , Adolescent , Adult , Eye Diseases/diagnosis , Eye Diseases/genetics , Female , Humans , Male , ProtonsABSTRACT
Magnetic resonance spectroscopy is a valuable method for the non-invasive investigation of metabolic processes and can now be combined with conventional magnetic resonance imaging in patients. This article gives a brief introduction into the principles and physiological and clinical applications of in vivo proton magnetic resonance spectroscopy, surveys experiences in healthy volunteers and presents exemplary results in patients suffering from cortical blindness or visual field defects. The causes of visual loss include brain trauma, cerebral ischemia, and brain tumors. In traumatic, ischemic and neoplastic lesions, an important spectral finding is an elevated lactate resonance which has been explained by increased anaerobic glycolysis of ischemic brain tissue and macrophages invading necrotic tissue. In our investigations using a clinical spectroscopy protocol on a 1.5 T MR system, a significant lactate signal was absent in spectra obtained from the visual cortex of normal volunteers, even during photic stimulation with a stroboscope. Other spectral changes in the patients include a decreased N-acetyl-aspartate resonance which indicates a decreased number of viable neurons in the examined brain region.
