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The purpose of this study was to assess the efficacy of model-based iterative reconstruction (MBIR), statistical iterative reconstruction (SIR), and filtered back projection (FBP) image reconstruction algorithms in the delineation of ureters and overall image quality on non-enhanced computed tomography of the renal tracts (NECT-KUB). This was a prospective study of 40 adult patients who underwent NECT-KUB for investigation of ureteric colic. Images were reconstructed using FBP, SIR, and MBIR techniques and individually and randomly assessed by two blinded radiologists. Parameters measured were overall image quality, presence of ureteric calculus, presence of hydronephrosis or hydroureters, image quality of each ureteric segment, total length of ureters unable to be visualized, attenuation values of image noise, and retroperitoneal fat content for each patient. There were no diagnostic discrepancies between image reconstruction modalities for urolithiasis. Overall image qualities and for each ureteric segment were superior using MBIR (67.5 % rated as 'Good to Excellent' vs. 25 % in SIR and 2.5 % in FBP). The lengths of non-visualized ureteric segments were shortest using MBIR (55.0 % measured 'less than 5 cm' vs. ASIR 33.8 % and FBP 10 %). MBIR was able to reduce overall image noise by up to 49.36 % over SIR and 71.02 % over FBP. MBIR technique improves overall image quality and visualization of ureters over FBP and SIR.

Elderly patients with upper tract urothelial cancer (UTUC) may present with colic and microscopic haematuria, mimicking urolithiasis. Patients presenting to emergency departments with acute ureteric colic are investigated with a CT KUB. CT urography (CTU) identifies UTUC better than a CT KUB. Thus, there is a possibility that a CT KUB may miss UTUC. We studied patients aged 65 years or over presenting to the emergency department with ureteric colic and microscopic haematuria who had a CT KUB between January 2014 and October 2016. Patients who had both CT KUB and CTU were then compared to determine if CT KUB had missed a UTUC and if the diagnoses were concordant by the two tests. A radiologist independent from the reporting radiologists reviewed images as well as their reports. According to the Health Research Authority, England regulations, we did not obtain an ethical review on a voluntary basis for this retrospective study. Four hundred eighty-five patients [228 (47.01%) male and 257 (52.99%) female] had a CT KUB scan over the 34-month period. Their mean age was 74 (SD 6.97) [males 73 (SD 6.42), females 75 (SD 7.42)] years. One hundred eighty-seven scans were normal. Ureteric calculi (167), renal calculi (58) and renal cysts (28) were most frequent diagnoses. The diagnosis was uncertain in 33 patients (6.8%) [16 (48.49%) males and 17 (51.51%) females]. The mean age of this group of patients was 74 (SD 6.64) [males 73 (SD4.43), females 74 (SD7.64)] years. These patients had a CTU for clarity. CTU identified one UTUC not identified by CT KUB (0.2%), corroborated the diagnosis of a ureteric tumour in one patient and excluded UTUC in two others. CTU diagnosed two new bladder tumours and an endometrial tumour. Diagnoses were concordant between CT KUB and CTU in 17 of 33 patients (51.5%). CT KUB scans for patients 65 years and over presenting with ureteric colic is justified. Only a small proportion of patients will subsequently require the higher radiation dose CTU as the probability of missing UTUC is low.