Four-and-one-half years' experience in monitoring of reproducibility of an MR spectroscopy system--application of in vitro results to interpretation of in vivo data.

The primary purpose of this work was to assess long-term in vitro reproducibility of metabolite levels measured using 1H MRS (proton magnetic resonance spectroscopy). The secondary purpose was to use the in vitro results for interpretation of 1H MRS in vivo spectra acquired from patients diagnosed with Canavan disease. 1H MRS measurements were performed in the period from April 2006 to September 2010. 118 short and 116 long echo spectra were acquired from a stable phantom during this period. Change-point analysis of the in vitro N-acetylaspartate levels was exploited in the computation of fT factor (ratio of the actual to the reference N-acetylaspartate level normalized by the reciprocity principle). This coefficient was utilized in the interpretation of in vivo spectra analyzed using absolute reference technique. The monitored time period was divided into six time intervals based on short echo in vitro data (seven time intervals based on long echo in vitro data) characterized by fT coefficient ranging from 0.97 to 1.09 (based on short echo data) and from 1.0 to 1.11 (based on long echo data). Application of this coefficient to interpretation of in vivo spectra confirmed increased N-acetylaspartate level in Canavan disease. Long-term monitoring of an MRS system reproducibility, allowing for absolute referencing of metabolite levels, facilitates interpretation of metabolic changes in white matter disorders.

Stress fractures in uncommon location: Six case reports and review of the literature.

BACKGROUND: Individuals' interest in sports activities has been increasing, contributing to more stress fracture occurrences in uncommon locations on the skeleton. In this study, several cases of stress fractures in atypical locations are presented, and the possibility of combining diagnostic methods to make accurate and quick diagnoses is explored. Additionally, different causes of stress fractures, as well as various modalities of treatment, are highlighted. Other potential factors of stress fractures were identified by a literature review. CASE SUMMARY: Six cases of stress fractures in the calcaneus, intermediate cuneiform bone, sacrum, tibia (bilateral), navicular bone and femoral neck are presented, with different types of diagnostic imaging and treatments. All of the cases were associated with an aspect of mobility because all of the patients were physically active in various sport disciplines. CONCLUSION: The type of therapeutic procedure selected should depend on the specific clinical case, i.e., the patient's condition and level of physical activity.

[Opsoclonus-myoclonus syndrome in a 2 year old boy with prenatally diagnosed retroperitoneal tumour]. / Zespol opsoklonie-mioklonie (the opsoclonus-myoclonus syndrome- OMS) u 2-letniego chlopca z rozpozpoznanym prenatalnie guzem przestrzeni zaotrzewnowej

Opsoclonus-myoclonus syndrome, also named Myoclonic Encephalopathy of Infants, Opsoclonus- Myoclonus Ataxia, Dancing Eyes - Dancing Feet Syndrome, Dancing Eyes Syndrome, Kinsbourne syndrome, is a rare, paraneoplastic or possibly post-viral chronic neurological disorder. The age of presentation ranges from 6 months to 3 years. In 50% of affected children the syndrome is associated with an underlying occult or clinically apparent neuroblastoma. In most patients the tumour is localized, small and well differentiated, with no NMYC gene copy number amplification. The syndrome may also occur after tumour resection or at relapse. The opsoclonus-myoclonus syndrome can occur in children without neuroblastoma, in such idiopathiccases, the onset of neurological symptoms is related to infection. It is assumed, that in idiopathic cases the syndrome could have developed in the course of neuroblastoma which had undergone a complete spontaneous regression. The most characteristic clinical features of opsoclonus-myoclonus syndrome are: opsoclonus, myoclonus, ataxia, irritability, mutism and sleep disturbances. The disease course is usually long-term with episodes of remission and relapses. Approximately 80% of children with opsoclonus-myoclonus syndrome suffer from mild to severe neurological handicaps, mainly cognitive impairment. The authors present a 2-year old boy with opsoclonus-myoclonus syndrome preceded by involution of prenatally documented retroperitoneal area tumour.