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Abstract
Purpose: This is prospective study to assess radiation dose, image quality, and diagnostic performance of computed tomography (CT) urography for detection of urothelial carcinomas by performing reduced-dose scanning with iterative reconstruction (IR) compared with standard-dose scanning with filtered back projection (FBP).
Materials and methods: Study was conducted on 21 patients sonographicaly diagnosed as bladder cancer presenting to the Radiodiagnosis Department at Alexandria University Hospitals. Patients underwent 2 groups according to body weight: ≤ 80 kg (n = 10)underwent standard dose with FBP 130 kVp (protocol A1) and additional scan limited to urinary bladder at delayed phase with low dose with IR 80 kVp (protocol B1) ,>80 kg (n = 11) into standard dose 130 kvp (protocol A2 )and additional scan limited to urinary bladder at delayed phase with (protocol B2); low dose 110 kvp.objective image quality (signal to noise SNR and contrast to noise ratio CNR) between the two groups with same weight range was measured for various regions of interest. Subjective image quality (visual image noise and overall image quality) were assessed with three- point scores, respectively and diagnostic accuracy (per lesion and per patient) were assessed.
Results: The mean effective dose (ED) for protocol A1(130kVp) was 5.49 mSv ± .43 and for protocol B1 (80 kVp) was 1.65 ± .92 with 70.8% decrease while for protocol A2 and B2 mean ED was 5.77 mSv ± .43 and 3.62 mSv ± .65 respectively with 38.1% decrease. There was significant difference in SNR between protocol A1 and B1 at aorta and psoas muscles whereas no significant difference was seen between protocol A2 and B2 at SNR and CNR (P ≤ 0.05 for all). Subjective image quality analyses were averaged among observers and revealed no statistically significant differences between the protocol A2(130 kvp) and B2(110 kvp) whereas there was significant difference between protocol A1(130kVp) and B1(80 kVp) as regards to visual image noise, and overall image quality. Diagnosis was identical among different protocols as regards per patient and per lesion levels analyses among observers with diagnostic accuracy 91.30% at patient level and 78.72% at lesion level .
Conclusion: To conclude Reduced-dose scanning with IR showed dose reduction and no difference in detection of urothelial carcinomas from standard dose with FBP, despite of degraded image quality in 80- kVp scanning.