Low-dose MDCT may locate urinary stone disease, even in overweight patients

Low-dose multidetector CT (MDCT) that uses a modulated tube current system may be as precise as the standard dose in the detection of urinary stone disease, regardless of the patient’s weight, Belgian researchers report. Further, MDCT exposes the patient to between 51.2% and 64.3% less radiation than the standard dose.

In a study published in the American Journal of Roentgenology (2007; 188:553-62), a total of 300 patients were enrolled; 150 received a standard-dose protocol, and 150 patients received the lower-dose protocol. Of the patient population, 158 had urinary stone disease; the difference in urinary stones between the standard and low-dose groups was not significant.

Radiologists realized an overall accuracy of approximately 97% for standard-dose and 95% for low-dose examinations, according to lead author Tom H. Mulkens, MD, of Heilig Hart Ziekenhuis in Lier, Belgium. For overweight and obese patients, the low-dose method had an accuracy rate of approximately 99%, he said.

Board-certified radiologists were able to make correct alternative diagnoses in 25 patients (15%) who received the lower dose, accurately identifying appendicitis, prostate cancer, and ovarian cysts and masses as the actual source of the patient’s symptoms. Overall diagnostic accuracy among first-year residents using low-dose and standard-dose MDCT was approximately 94%.