Significance of unilateral diminished activity in renal scanning

Renal scanning is an important diagnostic aid in assessing kidney function; the authors have attempted to correlate the results of renal scanning with the findings from intravenous pyelography and the final diagnosis. In non-mass lesions of the kidney the renal scan correlated well with the intravenous pyelogram and the final diagnosis. In mass lesions, a diminished uptake of isotope corresponding to the site of the lesion seen on the intravenous pyelogram was suggestive of a cyst; diminished uptake of isotope in the whole kidney including the mass lesion on the renal scan was suggestive of renal carcinoma. Review of the literature showed only one previous reference to such an observation.