Fetal brain MRI texture analysis identifies different microstructural patterns in adequate and small for gestational age fetuses at term.

OBJECTIVES: We tested the hypothesis whether a texture analysis (TA) algorithm applied to MRI brain images identified different patterns in small for gestational age (SGA) fetuses as compared with adequate for gestational age (AGA). STUDY DESIGN: MRI was performed on 83 SGA and 70 AGA at 37 weeks' GA. Texture features were quantified in the frontal lobe, basal ganglia, mesencephalon, cerebellum and cingulum. A classification algorithm based on discriminative models was used to correlate texture features with clinical diagnosis. RESULTS: Region of interest delineation in all areas was achieved in 61 SGA (12 vasodilated) and 52 AGA; this was the sample for TA feature extraction which allowed classifying SGA from AGA with accuracies ranging from 90.9 to 98.9% in SGA versus AGA comparison and from 93.6 to 100% in vasodilated SGA versus AGA comparison. CONCLUSIONS: This study demonstrates that TA can detect brain differences in SGA fetuses. This supports the existence of brain microstructural changes in SGA fetuses.

Abnormal brain microstructure and metabolism in small-for-gestational-age term fetuses with normal umbilical artery Doppler.

OBJECTIVES: To assess microstructural and metabolic brain differences between small-for-gestational age (SGA) and appropriate-for-gestational age (AGA) fetuses at 37 weeks' gestation by magnetic resonance imaging (MRI) spectroscopy and diffusion weighted imaging. METHODS: Eight SGA and five matched AGA singleton fetuses, all with normal umbilical artery Doppler, were evaluated using MRI at 37 weeks to measure markers of brain microstructure and metabolism. The metabolic spectrum of N-acetyl-aspartate/choline, choline/creatine, inositol/choline and creatine/choline ratios in the left frontal lobe and the apparent diffusion coefficient from the right and left basal ganglia and frontal and occipital lobes, pyramidal tract and corpus callosum were analyzed and compared. RESULTS: As compared with controls, SGA fetuses showed a significant increase in inositol/choline ratio (SGA, 0.57 vs. AGA, 0.25; P = 0.04) and significantly higher ADC values in the pyramidal tract (SGA, 119.87 x 10(-5) mm(2)/s vs. AGA, 105.11 x 10(-5) mm(2)/s; P = 0.04). CONCLUSIONS: SGA fetuses with normal umbilical artery Doppler present microstructural and metabolic brain changes, suggesting the existence of an abnormal in-utero brain development in fetuses with this condition.

Starch-based backwards SHG for in situ MEFISTO pulse characterization in multiphoton microscopy.

We report a simple methodology to provide complete pulse characterization at the sample plane of a two-photon excited fluorescence (TPEF) microscope. This is achieved by using backward propagating second-harmonic generation (SHG) from starch granules. Without any modification to the microscope, SHG-autocorrelation traces were obtained by using a single starch granule that was placed alongside the biological specimen being imaged. A spectrally resolved SHG autocorrelation was acquired by placing a spectrometer at the output port of the microscope. Complete in situ pulse information is then directly retrieved in an analytical way using the measurement of electric filed by interferometric spectral trace observation (MEFISTO) technique.