Diffusion and perfusion magnetic resonance imaging of the evolution of hypoxic ischemic encephalopathy in the neonatal rabbit

Hypoxic-ischemic encephalopathy (HIE) can result from neonatal asphyxia, the pathophysiology of which is poorly understood. We studied the acute evolution of this disease, using magnetic resonance imaging in an established animal model. HIE was induced in neonatal rabbits by a combination of common carotid artery (CCA) ligation and hypoxia. Serial diffusion and perfusion-weighted magnetic resonance images were acquired before, during, and after the hypoxic interval. Focal areas of decreased apparent diffusion coefficient (ADC) were detected initially in the cortex ipsilateral to CCA ligation within 62 ± 48 min from the onset of hypoxia. Subsequently, these areas of decreased ADC spread to the subcortical white matter, basal ganglia (ipsilateral side), and then to the contralateral side. Corresponding perfusion-weighted images showed relative cerebral blood volume deficits which closely matched those regions of ADC change. Our results show that MRI diffusion and perfusion-weighted imaging can detect acute cell swelling post-hypoxia in this HIE model.     

Pain with Amniocentesis and Transabdominal CVS

Fifty consecutive patients undergoing transabdominal chorionic villus sampling (CVS) and 52 undergoing amniocentesis completed a questionnaire following the procedure to determine the amount of pain they experienced. Mild pain, discomfort only or no pain was reported by 96% undergoing amniocentesis and 90% with CVS. Moderate or severe pain was reported after completion of the CVS by 8% and following amniocentesis by 2%. Both procedures were well tolerated.     

Cardiac tagging in the rat using a DANTE sequence

We demonstrate the application of a DANTE tagging sequence to in vivo imaging of the rat heart. This sequence generates narrow parallel tag lines in a short space of time and is combined with cardiac gating to image the heart wall at eight points throughout the cycle.     

Amniocentesis: a Comparison of ''Monitored'' versus ''Blind'' Needle Insertion Technique

The incidence of complications following 382 'blind' amniocenteses, in which ultrasound was used prior to but not during the procedures, was compared with those following 482 'continuously monitored' amniocenteses. The monitored technique was associated with a reduction in the incidence of blood-stained amniotic fluid, the number of attempts required to obtain fluid and with a fall in the number of spontaneous abortions from 9 (2.4%) to 4 (0.8%).     

Caffeine potentiates the nephrotoxicity of mefenamic acid on the rat renal papilla

The effect of caffeine given in combination with mefenamic acid on the renal papilla was studied. Sprague-Dawley rats were divided into four groups and gavage fed either control suspension, mefenamic acid, mefenamic acid and caffeine or caffeine alone for 4 months. Semiquantitative urinalysis was performed at 3 months and showed increased haematuria in the mefenamic acid and caffeine group. There were no significant differences in serum creatinine at sacrifice. Renal histology revealed more advanced papillary necrosis in rats gavage fed mefenamic acid and caffeine compared with all other groups (p less than 0.0001). Rats fed mefenamic acid alone showed more damage than control and caffeine-fed groups (p less than 0.0001, p less than 0.0002, respectively). This suggests that caffeine potentiates the nephrotoxicity of the non-steroidal anti-inflammatory drug, mefenamic acid, on the rat renal papilla. The mechanism of this potentiation by caffeine is yet to be defined.     

3D micro-CT imaging of the postmortem brain

Magnetic resonance microscopy (microMRI) is becoming an important tool for non-destructive analysis of fixed brain tissue. However, unlike MRI, X-ray computed tomography (CT) scans show little native soft tissue contrast. In this paper, we explored the use of contrast enhanced (brains immersion stained in iodinated CT contrast media) micro-CT (microCT) for high resolution 3D imaging of fixed normal and pathological brains, compared to microMRI and standard histopathology. An optimum iodine concentration of 0.27 M resulted in excellent contrast between gray and white matter in normal brain and a wide range of anatomical structures were identified. In glioma bearing mouse brains, there was clear deliniation of tumor margin which closely matched that seen on histopathology sections. microCT tumor volume was strongly correlated with histopathology volume. Our data suggests that microCT image contrast in the immersion-stained brains is related to axonal density and myelin content. Compared to traditional histopathology, our microCT approach is relatively rapid and less labor intensive. In addition, compared to microMRI, microCT is robust and requires much lower equipment and maintenance costs. For simple measurements, such as tumor volume and non-destructive postmortem brain screening, microCT may prove to be a valuable alternative to standard histopathology or microMRI.     

Medicolegal activity in obstetrical and gynaecological ultrasound.

We surveyed obstetricians who are members of the Australian Association of Obstetrical and Gynaecological Ultrasonologists for details of actions in which they had been asked to give an expert opinion between 1993 and 1998. We uncovered 50 cases, most of which involved missed fetal anomalies. Our findings suggest there is considerable medicolegal activity in obstetrical and gynaecological ultrasound in Australia.