Central lucency of pelvic phleboliths: comparison of radiographs and noncontrast helical CT.

To compare how often the central lucency of pelvic phleboliths is seen on plain radiographs and noncontrast helical computed tomography (CT), both images in 70 patients with renal colic were analyzed. Both images revealed the same number of phleboliths in all cases except one in which one of two phleboliths demonstrated by CT was not seen on radiographs. Radiography revealed central lucency in 95 of 149 pelvic phleboliths (63%), but CT failed to depict a hypodense center in any of 150 phleboliths. The presence or absence of central lucency on CT images cannot, therefore, be used to differentiate phleboliths from distal ureteral calculi.