In vivo magnetic resonance spectroscopy: basic methodology and clinical applications

The clinical use of in vivo magnetic resonance spectroscopy (MRS) has been limited for a long time, mainly due to its low sensitivity. However, with the advent of clinical MR systems with higher magnetic field strengths such as 3 Tesla, the development of better coils, and the design of optimized radio-frequency pulses, sensitivity has been considerably improved. Therefore, in vivo MRS has become a technique that is routinely used more and more in the clinic. In this review, the basic methodology of in vivo MRS is described—mainly focused on 1H MRS of the brain—with attention to hardware requirements, patient safety, acquisition methods, data post-processing, and quantification. Furthermore, examples of clinical applications of in vivo brain MRS in two interesting fields are described. First, together with a description of the major resonances present in brain MR spectra, several examples are presented of deviations from the normal spectral pattern associated with inborn errors of metabolism. Second, through examples of MR spectra of brain tumors, it is shown that MRS can play an important role in oncology

Long-term follow-up and treatment in nine boys with X-linked creatine transporter defect

The creatine transporter (CRTR) defect is a recently discovered cause of X-linked intellectual disability for which treatment options have been explored. Creatine monotherapy has not proved effective, and the effect of treatment with L-arginine is still controversial. Nine boys between 8 months and 10 years old with molecularly confirmed CRTR defect were followed with repeated 1H-MRS and neuropsychological assessments during 4–6 years of combination treatment with creatine monohydrate, L-arginine, and glycine. Treatment did not lead to a significant increase in cerebral creatine content as observed with H1-MRS. After an initial improvement in locomotor and personal-social IQ subscales, no lasting clinical improvement was recorded. Additionally, we noticed an age-related decline in IQ subscales in boys affected with the CRTR defect

Acute mountain sickness.

Acute mountain sickness (AMS) is a clinical syndrome occurring in otherwise healthy normal individuals who ascend rapidly to high altitude. Symptoms develop over a period ofa few hours or days. The usual symptoms include headache, anorexia, nausea, vomiting, lethargy, unsteadiness of gait, undue dyspnoea on moderate exertion and interrupted sleep. AMS is unrelated to physical fitness, sex or age except that young children over two years of age are unduly susceptible. One of the striking features ofAMS is the wide variation in individual susceptibility which is to some extent consistent. Some subjects never experience symptoms at any altitude while others have repeated attacks on ascending to quite modest altitudes. Rapid ascent to altitudes of 2500 to 3000m will produce symptoms in some subjects while after ascent over 23 days to 5000m most subjects will be affected, some to a marked degree. In general, the more rapid the ascent, the higher the altitude reached and the greater the physical exertion involved, the more severe AMS will be. Ifthe subjects stay at the altitude reached there is a tendency for acclimatization to occur and symptoms to remit over 1-7 days

Guanidino compounds in guanidinoacetate methyltransferase deficiency, a new inborn error of creatine synthesis

Contains fulltext : 25938___.PDF (publisher's version ) (Open Access

Disorders of creatine metabolism

Primary disorders of creatine metabolism are a group of inborn errors of creatine synthesis (arginine:glycine amidinotransferase (AGAT, encoded by GATM), guanidinoacetate methyltransferase (GAMT, encoded by GAMT) deficiencies), and the X-linked creatine transporter (CRTR, encoded by SLC6A8) deficiency. They typically present with systemic and/or cerebral creatine deficiency and global developmental delay, cognitive dysfunction or intellectual disability along with epilepsy, movement disorders and behavioural problems. Diagnostic markers include high guanidinoacetate concentrations in body fluids in GAMT and low levels in AGAT deficiency in both sexes and increased urine creatine to creatinine ratio in CRTR deficiency in males and rarely in females. Oral creatine supplementation, leads to near complete restoration of cerebral creatine in creatine synthesis defects: In GAMT deficiency, reduction of guanidinoacetate is achieved by ornithine supplementation and / or dietary protein or arginine restriction. In CRTR deficiency, creatine, arginine and glycine supplementation does not significantly improve outcomes, although partial clinical improvement has been reported in few patients. Normal neurodevelopmental outcomes have been reported in early treated patients with creatine synthesis defects