Detection of bladder cancer: comparison of low-dose scans with AIDR 3D and routine-dose scans with FBP on the excretory phase in CT urography

Abstract

Objective: To prospectively compare the detection of bladder cancer between low-dose scans with adaptive iterative dose reduction three dimensional projection (AIDR 3D) and routine-dose scans with filtered back projection (FBP) on the excretory phase (EP) in CT urography. Methods: 42 patients were included. Routine-and lowdose EP were performed in each patient. Routine-dose images were reconstructed with FBP, and low-dose images were reconstructed with AIDR 3D. Two radiologists scored confidence levels for the presence or absence of bladder cancer using a 5-point scale. The CT dose index of each EP was measured, and the dose reduction was calculated.Results: Sensitivity, specificity and accuracy were 86.4%, 95.0% and 90.5% on routine-dose scans and were 86.4%, 90.0% and 88.1% on low-dose scans, respectively. There was no significant difference (p; not significant, 1.00 and 1.00, respectively). The average CT dose index was 8.07 and 2.63 mGy on routine-and low-dose scans, and the ratio of dose reduction was 67.6%. Conclusion: The detection of bladder cancer on low-dose scans with AIDR 3D is almost equal to that on routine-dose scans with FBP on the EP, with nearly 70% dose reduction. Advances in knowledge: Using AIDR 3D, the radiation dose may be reduced on the EP in CT urography for the detection of bladder cancer. INTRODUCTIONCT urography (CTU) is not the primary methodology for investigation of macroscopic haematuria; moreover, cystoscopy remains the gold standard for making the diagnosis. However, CTU is an excellent technique for the evaluation of calculi and masses in the urinary system performed using the helical scan.1-3 The contrast resolution of CTU is superior to that of conventional excretory urography and has become one of the robust imaging tools for the evaluation of the urinary system.2 However, CTU results in higher radiation exposure than conventional excretory urography.1-4 Therefore, the reduction of radiation dose on CTU is an important problem to be resolved.

Reduction of the radiation dose and the amount of contrast material in hepatic dynamic CT using low tube voltage and adaptive iterative dose reduction 3-dimensional

“…Adaptive iterative dose reduction 3-dimensional (AIDR 3D; Toshiba Medical Systems, Otawara, Japan) is a hybrid IR algorithm, which has already been used in abdominal and pelvic CT with reduced dose scans. [ 17 – 25 ] However, the combination of hepatic dynamic CT with low tube voltage technique and AIDR 3D has not been investigated. Moreover, to our knowledge, there are no previous reports which have evaluated the diagnostic ability of low tube voltage hepatic dynamic CT with IR using a free-response methodology such as the jackknife free-response receiver-operating characteristic (JAFROC) analysis, which has been reported to yield greater statistical power at detecting modality differences.…”

CT urography: principles and indications

“…Recently introduced iterative reconstruction algorithms improved image quality and allowed dose reduction by additional 40-50% with reported radiation dose of 6. 1 mSv for a triple phase protocol, and possible split bolus study at 4.2 mSv [33][34][35] . …”