Evaluation of small (</= 3 cm) renal masses with MDCT: benefits of thin overlapping reconstructions.
OBJECTIVE
Our purpose was to determine whether thin overlapping reconstructions using MDCT improve the detection and characterization of small renal masses.


METHODS
Thirty-seven patients were scanned with MDCT using 2.5-mm collimation. Nephrographic phase data were reconstructed in two ways: a standard protocol (5-mm section thickness, no overlap) and an experimental protocol (3-mm section thickness, 50% overlap). Masses were detected and classified into three groups: group 1, measuring less than 20 H on both protocols (classified as cysts on both); group 2, measuring 20 H or greater on standard protocol and less than 20 H on experimental protocol (classified as cysts using experimental protocol only); and group 3, measuring 20 H or greater on both protocols (not classified as cysts using either protocol). Masses 10 mm or larger in group 3 were evaluated further for enhancement. Statistically significant differences between protocols were assessed using an analysis of counts and proportions.


RESULTS
Of 175 detected lesions, 29 (17%) were detected only with the experimental protocol; all but one were smaller than 5 mm. Using the experimental protocol, of 45 masses between 5 and 10 mm, the number of masses that could be characterized as cysts increased from 13 (29%) to 38 (84%). The overall number of indeterminate lesions was reduced from 101 (69%) of 146 lesions detected with the standard protocol to 86 (53%) of 161 lesions detected with the experimental protocol.


CONCLUSIONS
Using MDCT and thin overlapping reconstructions, renal cysts as small as 5 mm can be diagnosed with more confidence than is possible with standard reconstructions, and the overall number of indeterminate renal masses is reduced.
Jinzaki
Masahiro
M
Department of Radiology, Brigham and Women's Hospital, 75 Francis St., Boston, MA 02115, USA. jinzaki@sc.itc.keio.ac.jp
McTavish
Jeffrey D
JD
Zou
Kelly H
KH
Judy
Philip F
PF
Silverman
Stuart G
SG
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007668:Kidney / Q000473:pathology; D052177:Kidney Diseases, Cystic / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods*