Nuclear-Medizin最新文献

A new technique using a single NaI(Tl) detector (9 cm x 6.3 cm) in two positions and based on the response curves of the detector has been described. Also a different approach to select the energy band was adopted which is helpful in reducing the dependence of counting efficiency on source depth. Various portions of the compton continuum were taken rather than confining to valley and photo-peak. For transverse uniformity it was found that the energy band which gave 50% normalized count rate at half depth would give a resultant flat response with least variation. For longitudinal uniformity the separation between the two positions of the detector need to be nearly equal to the full width at half maximum of the response curve. The response curve coupling technique described here is different from the commonly used technique of iso-response curves.

The determination of 131-I-Hippuran clearance in connection with renography or renal camera sequential scintigraphy will give a quantitative evaluation of total and individual renal function. The "single shot" method of Oberhausen yields clearance values corresponding very well to the PAH standard clearance. To simplify this method for routine use in connection with camera sequential scintigraphy, we studied some modifications of the method, using regional activity curves instead of the activity curve of the partially shielded whole body. Simultaneously with the camera sequential scintigraphy we measured activity curves of the partially shielded whole body (lead-shielding of kidneys and bladder, two probes), the shoulder (one probe), the head (one probe) and a background region of the camera (ROI) above the kidneys for 30 min. All four curves were analyzed, using computer analysis (bi-exponential curve fitting) as well as tables of Oberhausen, and his formula was used for clearance calculation. Under two conditions a) taking blood samples between 15 and 25 min. p.i. b) using the tables of Oberhausen for curve analysis, the clearance out of the regional activity curves correlates well with the clearance out of the partially shielded whole body activity curve (r greater than 0,97). Therefore, it is possible determine 131-I-Hippuran clearance in a simple manner without lead-shielding of kidneys and bladder, either with one additional probe measurement at shoulder or head or without any probe measurement, using the camera and measuring a background curve (ROI) above the kidneys. This simple clearance method can easily be performed simultaneously with 131-I-Hippuran renography or renal camera sequential scintigraphy in routine.

The effect of various doses of sodium perchlorate in several dose fractions on the extent and the time scale of displacement of radiopertechnetate, in dependence on application mode, was studied. An intravenous dose of 50 mg perchlorate was in respect of competitive suppression of organs actively concentrating pertechnetate as effective as intravenous 1000 mg ClO-4- simultaneously or 1000 mg orally 30 min before the injection of radiopertechnetate. An intravenous injection of perchlorate given later also produces a complete and immediately beginning depletion of pertechnetate already accumulated in the thyroid, within a period of 195 min after 99m-TcO-4-injection with a corresponding increase in blood levels. 20 mg result in incomplete depletion which becomes complete after a second additional dose. The intravenous application of perchlorate offers advantages in clinical use.

In order to estimate the renal plasma flow and glomerular filtration rate during the course of renography, a method was developed using simultaneously 131I Hippuran and 169Yb DTPA. First results obtained in a survey of approximately 200 patients are encouraging. The method permits an accurate evaluation of the renal function. In addition, by comparing the clearance rate of the two radiocompounds one can also obtain some interesting diagnostic information which can contribute usefully to the interpretation of renographic tracings and/or gamma camera sequential images.

Radiorenography, serial scans and clearance determinations using 131-I-Iodohippurate and 51-CPr-EDTA were performed on a total of 106 patients with unilateral nephroptosis. In 45 of them with pathological findings in the upright position the examination was repeated in the prone position. 19 patients underwent nephropexy and were reexamined 2 to 6 weeks there after. The results suggest that the combination of different radioisotope methods provides a valuable and sensitive means to detect posture-dependent impairment of kidney and urinary tract function and yields an additional objective basis for the selection of patients for nephropexy.