Magnetic resonance renography: optimisation of pulse sequence parameters and Gd-DTPA dose, and comparison with radionuclide renography.

The aim of this study was to assess the feasibility of magnetic resonance renography (MRR) using gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) in comparison with conventional radionuclide renography (RR) using technetium-99m-DTPA (99mTc-DTPA). MRR has many advantages over RR, including lack of ionising radiation, increased spatial resolution, and visible background anatomy. By optimising the pulse sequence, we developed an MRR protocol in which signal intensity is linear with Gd-DTPA concentration over a clinically relevant range. Twenty-nine patients and a volunteer were studied using this protocol. Magnetic resonance renography was performed using three different doses of Gd-DTPA: 0.1 mmol kg-1 (n = 13), 0.05 mmol kg-1 (n = 7), and 0.025 mmol kg-1 (n = 9). Each patient was also assessed using radionuclide renography. The resulting renograms were assessed in terms of time to peak signal intensity, signal decrease after peak, and kidney function ratios calculated from both the areas underneath and the slopes of the uptake curves. We have shown that the MR renograms obtained using low dose Gd-DTPA correlate best with the radionuclide renograms. Remaining discrepancies may be explained by variations in the injection procedures (hence in arterial input functions) and the limited coverage of the three MRR slices compared to the whole body projection of RR. Furthermore, at high local concentrations, signal becomes independent of T1 and is dominated by T2.

Corynebacterium striatus keratitis.

We report a case of diphtheroid keratitis that occurred in a compromised cornea. Corneal cultures yielded heavy growth of Corynebacterium striatus on blood and chocolate agar. The infection responded slowly to treatment with topical fortified cefazolin and fortified tobramycin. This case demonstrates that diphtheroids are capable of causing ocular infections and should not routinely be dismissed as contaminants or commensals.

Ligation of patent ductus arteriosus in premature infants.

Twenty-four neonates at 25-34 weeks' gestation with a weight range of 570-1530 g underwent ligation of patent ductus arteriosus (PDA). The infants had mild to severe respiratory distress syndrome at birth and later developed signs of heart failure as a result of left-to-right shunting through a PDA. Surgical closure of the PDA was performed within 2-31 days after birth. In the period before operation the heart rate was monitored constantly and the arterial blood-gases were assessed frequently. The trachea was intubated and respiration was controlled with a ventilator. Surgery was performed under controlled ventilation and no anaesthesia was used. Care was taken not to overventilate the lungs. Nine infants died. Death was associated with higher peak inspiratory ventilator pressures at the time of operation and with complications occurring during or after the operation. The most common complication was tension pneumomediastinum which appears to be related to excessive ventilator pressures during surgery.