Reduced dose MDCT able to detect urinary stones in larger patients
MDCT (multidetector CT) performed using a modulated tube current system can result in a 64 percent reduction in standard radiation dose without compromising accuracy in the detection of urinary stone disease regardless of the size of the patient, according to a recent study published in The American Journal of Roentgenology.
The study involved 300 patients, 150 of them undergoing a standard dose protocol and 150 patients undergoing a lower-dose protocol. Of the 300 patients, 158 had urinary stone disease.
The overall accuracy by experienced radiologists was about 97 percent for standard-dose and 95 percent for low-dose examinations, said Tom H. Mulkens, MD, of Heilig Hart Ziekenhuis in Lier, Belgium, a lead author of the study. The low-dose procedures had about a 99 percent accuracy rate for overweight and obese patients, Mulkens added.
The overall accuracy by first-year residents for both low-dose and standard radiation dose examinations was about 94 percent.
The lower dose examination also allowed for accurate alternative diagnoses by radiologists in 15 percent of the patients. The diagnoses included disorders and diseases such as appendicitis, prostate cancer and ovarian cysts and masses. These ailments ended up being the cause of the patient’s symptoms rather than urinary stone disease.
However, the residents made an accurate alternative diagnosis in just 4-5 percent of the 25 patients, Mulkens said.
Mulkens noted that CT without the use of contrast media is a limited examination, and many alternative diagnoses, cannot be made regardless of the dose used. He added that a complete CT examination using contrast needs to be performed in cases where the patient has persistent clinical symptoms.