Assessment of the corticospinal tract alterations before and after resection of brainstem lesions using Diffusion Tensor Imaging (DTI) and tractography at 3T.

The purpose of the study was to investigate the role of Diffusion Tensor Imaging (DTI) and Diffusion Tensor Tractography (DTT) on the corticospinal tract alterations due to space occupying lesions in the brainstem before and after surgical resection. Pre- and post-surgical DTI data were acquired in 14 patients undergoing surgical resection of brainstem lesions. Patterns of corticospinal tract (CST) alteration on DTT were compared with the neurological exams of the patients pre- and post-operatively. DTT, especially in 3D movie format, seemed very helpful for evaluating the relationship of the lesions with the corticospinal tracts for surgical approach. None of the patients developed additional motor deficit related to surgery except one patient who presented with cerebellar ataxia after surgery. All of the patients with normal CST on DTT presented without motor deficit on neurological exam. The sensitivity, specificity, positive predictive and negative predictive values of DTT before surgery were 100%, 63.6%, 42.9% and 100%, and the corresponding values after surgery were 100%, 96%, 75% and 100% respectively. Although it has low specificity before surgery, DTT is a potentially useful technique in evaluating the effects of brainstem lesions and surgical resection on the relevant corticospinal tracts with high negative predictive value and higher specificity after surgery.

Doppler studies in normal kidneys of preterm and term neonates: changes in relation to gestational age and birth weight.

OBJECTIVE: The purpose of this study was to establish normative data for the flow velocity waveform indices of the renal arteries in the neonatal population and to evaluate the differentiation between birth weight and gestational age of neonates. METHODS: Color sonography was performed in 65 neonates on the fifth day of life. Mean flow velocity was assessed, and measurements of the systolic/diastolic velocity ratio, resistive index, and pulsatility index were performed by online calculation. RESULTS: All established values of renal arteries showed no significant differences in the right and left kidneys (P > .05). These values were not correlated with gestational age and birth weight (P > .05). CONCLUSIONS: Peak systolic velocity, systolic/diastolic velocity ratio, and resistive index and pulsatility index values remain stable despite gestational age or birth weight and not different between the right and left kidneys.