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[Virtual cystoscopy with reduced tube current: an alternative to cystoscopy?]
T M Bernhardt1, U W Krause, C Philipp
1Institut für Klinische Radiologie, Universität Münster, Münster. bernhart@uni-muenster.de
Purpose:
Virtual cystoscopy at different mAs settings in patients with tumors of the bladder in comparison with cystoscopy and axial CT.
Materials And Methods:
The study included 28 patients with bladder tumors and 28 patients without tumors as control group. The bladder was distended with air and scanned at two different mAs settings (protocol 1 and 2). The radiation exposure was reduced by 82 % for protocol 2 in comparison with protocol 1. Three readers compared virtual cystoscopy with cystoscopy and axial CT as to tumor location and size. Sensitivity, specificity and accuracy were calculated.
Results:
Of the 47 tumors seen at cystoscopy, all readers detected 45 tumors by virtual cystoscopy using protocol 1 and 44 tumors using protocol 2, with p > 0.05 in comparison with cystoscopy. Virtual cystoscopy showed higher sensitivity than axial CT (97.2 % vs. 86.5 % for protocol 1) and (96.5 % vs. 86.5 % for protocol 2) with the same specificity (100 %). The accuracy was 0.982 for protocol 1 and 0.978 for protocol 2. In comparison with virtual cystoscopy, axial CT shoved more often over- and underestimation of the tumor size.
Conclusion:
Virtual cystoscopy at reduced mAs setting is a modality suitable for the detection of polypoid tumors, but does not provide data of the mucosa and thus cannot replace cystoscopy yet.