Radionuclide techniques for the evaluation of diseases of the urinary tract in children

This review is directed toward a description of radionuclide techniques for the evaluation of disease of the urinary tract in children. The literature in this area is relatively sparse, and therefore the vast majority of the references are taken from adult experience. However, all the techniques described have been used by the authors and have been found to be equally applicable in children. Single injection clearances have gained a great deal of interest over the last several years since their simplicity and ease of performance offer particular advantages in dealing with children. The radio-hippuran renogram also has its place in evaluation of obstructive disease of the urinary tract but has yet to be fully appreciated by the practicing pediatrician. The renogram is particularly useful when combined with scintigraphy and computer analysis with area of interest generation of the curves. At the termination of a renogram it is perfectly feasible to also measure the residual urine if any exists. Scintigraphy is of use in patients with uremia for outlining the position and size of the kidneys and also can be used in the evaluation of a variety of congenital anomalies of the kidney including horseshoe kidney and crossed renal ectopia. Various combined radionuclide studies employing ⁹⁹Tc pertechnetate and ³¹¹I-orthoiodohippurate may be useful in the evaluation of trauma. These studies demonstrate the presence of renal infarction and segmental areas of abnormal renal function. Ureterovesical reflux may also be demonstrated by the instillation of ^99mTc pertechnate into the urinary bladder with subsequent counting over the region of the kidneys. The field of renal transplantation, which is rapidly extending into the pediatric age group, has been greatly aided by the availability of radionuclide tests, especially serial sequential scintiphotos, which demonstrate the vascular patency of the anastomosis and the ability of the transplanted kidney to extract hippuran from the blood stream. A limited use for radiorenography and scintigraphy also exists in patients who have demonstrated contrast media sensitivity or in whom renal biopsy is to be performed and fluoroscopic localization of the kidney is not readily available.