Quantification of diagnostic biomarkers to detect multiple sclerosis lesions employing (1)H-MRSI at 3T.

Proton magnetic resonance spectroscopic imaging ((1)H-MRSI) enables the quantification of metabolite concentration ratios in the brain. The major purpose of the current work is to characterize NAA/Cho, NAA/Cr and Myo/Cr in multiple sclerosis (MS) patients, and to estimate their reproducibility in healthy controls. Twelve MS patients and five healthy volunteers were imaged using (1)H-MRSI at 3T. Eddy current correction was performed using a single-voxel non-water suppressed acquisition on an external water phantom. Time-domain quantification was carried out using subtract-QUEST technique, and based on an optimal simulated metabolite database. Reproducibility was evaluated on the same quantified ratios in five normal subjects. An optimal database was created for the quantification of the MRSI data, consisting of choline (Cho), creatine (Cr), N-acetyl aspartate (NAA), lactate (Lac), lipids, myo-inositol (Myo) and glutamine + glutamate (Glx). Decreasing of NAA/Cr and NAA/Cho ratios, as well as an increase in Myo/Cr ratio were observed for MS patients in comparison with control group. Reproducibility of NAA/Cr, NAA/Cho and Myo/Cr in control group was 0.98, 0.87 and 0.64, respectively, expressed as the squared correlation coefficient R (2) between duplicate experiments. We showed that MRSI alongside the time-domain quantification of spectral ratios offers a sensitive and reproducible framework to differentiate MS patients from normals.

Incidence and risk factors of retinopathy of prematurity in a tertiary eye hospital in Tehran.

AIM: To determine the incidence and risk factors of retinopathy of prematurity (ROP) in premature infants referred to a tertiary eye hospital during 2003-7 to provide preliminary evidence about ROP in Iran. METHODS: In a cross-sectional study, data for premature infants screened for ROP in Farabi Eye Hospital including possible risk factors and eye exams' results were recorded and analysed using chi(2), univariate and multiple regressions. Severe ROP was defined as ROP needing treatment or stage 4 or 5 of ROP. RESULTS: Among 953 premature infants, there were 329 (34.5%) different stages of ROP. Severe ROP was seen in 22.6% (215/953) of infants (16.5%: treatable, 6.1%: advanced untreatable). The mean gestational age (GA) and birth weight (BW) of infants with severe ROP were 28.8 (SD 2.4) weeks and 1256 (389) g respectively. Univariate analysis showed a significant relation between GA, BW, oxygen therapy, blood transfusion and ROP (p<0.001), while multiple-regression methods showed GA, BW and oxygen therapy as independent predictors of ROP (p<0.001, 0.019 and 0.033, respectively). CONCLUSION: The authors observed a relatively high incidence of ROP in this series, especially its severe form affecting relatively more mature infants, which merits further investigation. GA, BW and oxygen therapy were independent ROP determinants.