Usefulness of low-dose nonenhanced computed tomography with iterative reconstruction for evaluation of urolithiasis: diagnostic performance and agreement between the urologist and the radiologist.
OBJECTIVE
To evaluate the efficacy of low-dose nonenhanced computed tomography (LDCT) with iterative reconstruction (IR) technique for urologists to detect urolithiasis by comparing diagnostic performance and interobserver agreement between the urologist and the uroradiologist.


METHODS
We evaluated the 116 patients with urinary stones (n = 197) using both conventional-dose nonenhanced computed tomography (CT) using filtered back projection (CDCT-FBP) and LDCT-IR. Scans were interpreted for stone characteristics, objective image noise, and subjective image assessment. Diagnostic performance and interobserver agreement of LDCT-IR were assessed between 1 urologist and 1 radiologist.


RESULTS
There were no significant differences in all stones. The average effective dose (mSV) in the all size groups was 5.92 (CDCT-FBP) and 1.39 (LDCT-IR), respectively (P <.001). The average effective dose reduction rate was 76.6%, allowing minimal additional radiation exposure from simultaneous CT. Objective image noise was higher in LDCT-IR (20.0-26.2; P <.01), but there was no significant difference in the Hounsfield unit between both CT protocols (52.3 and 56.7; P = .103). There were no cases of any unacceptable images in subjective image assessment. The sensitivity and specificity of LDCT-IR were 99.1%-100.0% with a diagnostic accuracy of 99.1%-100% for stones ≥3 mm. Diagnostic performance was similar between the urologist and the radiologist. Interobserver agreement of LDCT-IR between the 2 reviewers was high with kappa values (0.901-1.000).


CONCLUSIONS
LDCT-IR provided an excellent diagnostic performance and interobserver agreement between the urologist and the uroradiologist, reducing radiation exposure significantly; in real settings, the urologist should consider replacing LDCT-IR as the standard examination for detecting urolithiasis.
Department of Urology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
Jong Kyou
JK
Kwon
Department of Urology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
In Ho
IH
Chang
Department of Urology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
Young Tae
YT
Moon
Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
Jong Beum
JB
Lee
Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
Hyun Jeong
HJ
Park
Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea. Electronic address: pksungbin@paran.com.
Sung Bin
SB
Park
D006801:Humans; D007091:Image Processing, Computer-Assisted; D007669:Kidney Calculi / Q000000981:diagnostic imaging*; D015588:Observer Variation; D011446:Prospective Studies; D011829:Radiation Dosage; D011871:Radiology / Q000706:statistics & numerical data*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014514:Ureteral Calculi / Q000000981:diagnostic imaging*; D052878:Urolithiasis / Q000000981:diagnostic imaging; D014572:Urology / Q000706:statistics & numerical data*