Ultrasonographic (US) findings were correlated with clinical outcome in seven cases of meconium peritonitis detected with prenatal US during a 2-year period. Nineteen previously reported cases were also reviewed. US findings included intraabdominal calcifications (n = six cases), fetal ascites (n = 3), echogenic ascites without calcifications (n = 1), bowel dilatation (n = 2), and polyhydramnios (n = 5). Following delivery, six infants were still alive after a mean follow-up of 13 months (range, 6-26 months); the seventh died of hydrocephalus. Of the six, four required surgical correction of a small-bowel perforation and two did not. All six are thriving, and none has yet been found to have cystic fibrosis. In the 19 previously reported cases, there were only two cases of cystic fibrosis, neither with intraabdominal calcifications. The presence of calcifications was significantly associated with causes other than cystic fibrosis. Prenatally diagnosed cases of meconium peritonitis are associated with cystic fibrosis less frequently than previous studies suggest.

Summary. The volumes and spin‐lattice (T1) relaxation times of breast tissues and parenchymal water content were measured non‐invasively by magnetic resonance imaging (MRI) in eight healthy women during four to eight consecutive menstrual cycles. Total breast volume, and parenchymal volume, T1 relaxation time and water content were lowest between days 6 and 15. Between days 16 and 28, parenchymal volume, T1 relaxation time and water content rose sharply by 38·9%, 15·1% and 24·5%, respectively, and peaked after day 25. Within 5 days of the onset of menses, parenchymal volume fell sharply by 30·3%, while water content declined by 17·5%. Rising parenchymal volume in the second half of the menstrual cycle is not solely due to increased tissue water content and provides in vivo evidence for both growth and increased tissue fluid at this time.

The design, construction and use of a large-scale field-cycled proton-electron double-resonance imaging (FC-PEDRI) imager is described. The imager is based on a whole-body sized, vertical field, 59 mT permanent magnet. Field cycling is accomplished by the field compensation method, and uses a secondary, resistive magnet with an internal diameter of 52 cm. The magnetic field can be switched from zero to 59 mT or vice versa in 40 ms. It is used with a double-resonance coil assembly (NMR/EPR) comprising a solenoidal NMR transmit/receive coil and a coaxial, external birdcage resonator for EPR irradiation. Experiments to image the distribution of an exogenous nitroxide free radical in anaesthetized rabbits are described.

In vitro and in vivo measurements of pH and thiols provide critical information on physiology and pathophysiology of living organisms, particularly related to oxidative stress. Stable nitroxides of imidazoline and imidazolidine types provide the unique possibility of measuring local values of pH and glutathione content in various biological systems, including in vivo studies. The basis for these applications is the observation of specific chemical reactions of these nitroxides with protons or thiols, followed by significant changes in the electron paramagnetic resonance (EPR) spectra of these probes, measured by low-frequency EPR techniques. The applications of some newly developed pH and SH probes in model systems of pharmacological interest, biological fluids, tissues, and cells as well as in vivo studies in isolated hearts and in the gut of living animals are discussed.

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