Discrimination between ureteral stent and stone by non-contrast helical computed tomography in the clinical setting.
OBJECTIVE
In urolithiasis with indwelling ureteral stent, an adequate visualization of retained stone is often obscured by the stent. In functional solitary kidney, it is essential to detect retained fragments before stent removal. We examined the capability of non-contrast helical computed tomography (NCHCT) in discriminating stone from stent.


METHODS
We assessed the CT of 21 radiopaque stones of 3-5 mm and four stents, and compared their attenuation values. In addition, two other cases with stent, in which only NCHCT by manipulating the setting could detect retained fragments.


RESULTS
No overlaps of attenuation value were found between the stones and stents. Although they had the same appearance in NCHCT with abdominal-window setting, in bone-window setting the contrasts of stones were reduced, while stents were still bright white.


CONCLUSIONS
We would discriminate the residual stone from the stent by manipulating window and level setting, and bone-window setting is easy to use.
Yoshida
Soichiro
S
Department of Urology, Saitama Medical Center, Saitama Medical School, Kawagoe, Saitama, Japan. soichiroyoshida2000@yahoo.co.jp
Hayashi
Tetsuo
T
Okada
Takemichi
T
Osada
Hisato
H
Honda
Norinari
N
Yamada
Takumi
T
D003937:Diagnosis, Differential; D005547:Foreign Bodies / Q000000981:diagnostic imaging*; D006801:Humans; D015607:Stents; D014057:Tomography, X-Ray Computed; D014514:Ureteral Calculi / Q000000981:diagnostic imaging*