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Objective: The purposes of this study were to determine whether patients with asymptomatic microscopic hematuria undergoing CT urography (CTU) meet the American Urological Association criteria for radiologic evaluation and to determine the yield of CTU for upper tract malignancy., Materials and Methods: A retrospective review was conducted of consecutive CTU examinations performed for asymptomatic microscopic hematuria in adult patients. Patients with clinical evidence suggestive of a benign cause of hematuria (stone, urinary tract infection, trauma) or prior urologic malignancy were excluded. The study group included 419 patients (173 men, 246 women). CT reports were reviewed to identify causes of hematuria in all cases. Evaluate for appropriateness was conducted with 200 randomly allocated patients. Urinalysis results were reviewed, and appropriate use of CTU was defined as more than 3 RBCs per high-power field in the absence of urinary tract infection. Cystoscopy results after CTU were noted., Results: In total, 58 of 200 patients (29.0%; 95% CI, 23.2-35.6%) did not meet American Urological Association criteria for radiologic evaluation. Fifteen (7.5%) received dipstick analysis only. Thirty-eight (19.0%) had urinalysis results showing 0-2 RBCs per high-power field. Five patients (2.5%) were found to have urinary tract infections. No upper tract urothelial neoplasms were identified (0/419; 95% CI, 0.0-0.9%). One solid renal mass was identified without pathologic confirmation. One possible bladder mass was seen at CTU but not visualized at subsequent cystoscopy., Conclusion: In 29.0% of examinations, CTU is performed for patients who do not meet the criteria for radiologic evaluation. The yield of CTU for upper urinary tract malignancy is low.

OBJECTIVE. The purpose of this study is to retrospectively assess the impact of iterative metal artifact reduction (IMAR) with iterative reconstruction (IR) on the image quality and diagnostic performance of CT urography in the evaluation of patients with hip prostheses, compared with IR alone. MATERIALS AND METHODS. CT urography examinations that were reconstructed using IR with and without IMAR were analyzed for 57 patients (29 women and 28 men; mean age, 74 years [range, 22-94 years]) with hip prostheses (40 unilateral and 17 bilateral). For quantitative analysis, image noise within the bladder was measured. Two radiologists (radiologist 1 [RAD1] and radiologist 2 [RAD2]) qualitatively evaluated the images using both a 5-point scale to assess the degree of visualization of artifacts and a 6-point scale to determine diagnostic confidence in visualization of the bladder, ureters, prostate or uterus, pelvic calcifications, and genitourinary abnormalities involving the bladder, distal ureters, prostate, uterus, and ovaries. RESULTS. The combination of IMAR and an IR technique provided improvement in quantitative and qualitative measurements ( p < 0.05). Forty-three genitourinary abnormalities were detected in 29 patients. Quantitative and qualitative comparisons of scans obtained with and without the use of IMAR, respectively, revealed image noise of 99.6 versus 173.3 HU and the following radiologist scores: for improvement of artifacts, 3.2 versus 1.6 (for RAD1) and 3.1 versus 1.6 (for RAD2); for visualization of the bladder, 3.6 versus 1.5 (RAD1) and 3.8 versus 1.6 (RAD2); visualization of the ureters, 3.8 versus 1.6 (RAD1) and 3.9 versus 1.7 (RAD2); visualization of the uterus, 4.3 versus 2.8 (RAD1) and 4.3 versus 2.6 (RAD2); visualization of the prostate, 4.5 versus 2.3 (RAD1) and 4.5 versus 2.2 (RAD2); diagnostic confidence for calcifications, 4.7 versus 3.5 (RAD1) and 4.7 versus 3.3 (RAD2); and diagnostic confidence for genitourinary abnormalities, 5.0 versus 3.2 (RAD1) and 4.8 versus 2.9 (RAD2), respectively. CONCLUSION. The addition of IMAR to IR led to statistically significant improvement in the retrospective diagnostic performance and image quality of CT urography for patients with hip prostheses, compared with IR alone.

Objective: The purpose of this study was to compare dual-energy CT (DECT) urography with a 50% reduced iodine dose to single-energy CT (SECT) urography with a standard iodine dose with respect to attenuation of renal vascular and urinary tract structures and with respect to image quality., Subjects and Methods: The study included 62 patients undergoing evaluation of urinary tract lithiasis, tumor, or hematuria. Thirty-one patients underwent DECT urography with a 50% reduced iodine dose and reconstruction at 50 and 77 keV. These subjects were sex, age, and size matched to a group of 31 patients who underwent 120-kVp SECT urography with a standard iodine dose. The mean iodine dose was 22 g for DECT and 44 g for SECT. Attenuation was measured at seven locations in the renal arteries, renal veins, and urinary tract. Two reviewers subjectively scored the image quality parameters image noise, sharpness of urinary tract contours, enhancement of urinary structures, and streak artifacts., Results: Mean DECT attenuation at 50 keV was the same as or greater than SECT attenuation at each of the seven locations. Measured image noise was highest at 50-keV DECT but was the same for 77-keV DECT and 120-kVp SECT. Mean subjective scores for DECT image quality parameters were the same as or higher than those of SECT, except for streak artifact and sharpness of urinary tract contours., Conclusion: DECT urography with a 50% reduced iodine dose may result in measured renal vascular and urinary tract attenuation the same as or higher than and image quality measurements and scores similar to those obtained with 120-kVp SECT urography with a standard iodine dose.

Objective: The purpose of this study is to prospectively compare the image quality of and confidence in the presence of a lesion on CT urography images acquired using filtered back projection (FBP) with 100% and 50% radiation doses with those for images simultaneously acquired using sinogram-affirmed iterative reconstruction with strength 3 (SAFIRE) with 50% and 25% radiation doses for patients with a high risk for urothelial carcinomas., Subjects and Methods: A total of 150 patients randomly underwent CT urography examinations performed using a dual-source single-energy scanner. After the radiation output of each tube was adjusted, datasets at three radiation dose levels were reconstructed using FBP and SAFIRE. Seven radiologists subjectively assessed image quality and confidence in the presence of a lesion for a total of 1200 datasets. Nonparametric methods for cluster data were used to estimate AUC values for variance methods on the basis of a noninferiority margin of 0.05., Results: The mean AUC value for image quality in SAFIRE with a 25% radiation dose was significantly lower than that of FBP with 100% radiation dose (p < 0.05 for all). The mean AUC values for the presence of a lesion were 0.907 and 0.894 for FBP, respectively, at 100% and 50% radiation doses, respectively, and 0.900 and 0.799 for SAFIRE at 50% and 25% radiation doses, respectively. However, the image quality of images acquired with SAFIRE at a 25% radiation dose was significantly inferior to that of images acquired with FBP at a 100% radiation dose., Conclusion: Regardless of the experience of the radiologist, CT urography images acquired with FBP and SAFIRE with a 50% radiation dose were noninferior to those acquired with FBP with a 100% radiation dose in terms of image quality and confidence in the presence of a lesion, whereas those acquired with SAFIRE with 25% radiation dose were inferior.

Objective: The purpose of this study was to find the optimal allocation ratio of contrast medium (CM) in split-bolus CT urography (CTU) and to investigate the effect of increased imaging delays for synchronous nephrographic-excretory phase imaging., Subjects and Methods: One hundred ninety-two patients were randomly assigned to one of three protocols with different allocation ratios of CM: group A, 30% of CM at first bolus and 70% of CM at second bolus; group B, 70% and 30%; or group C, 50% and 50%. Saline (250 mL) was administered after the first CM bolus. Patients were subdivided by different imaging delay times (8, 10, 12, and 14 minutes). The attenuation values of the renal cortex and medulla were measured, and the opacification and maximal caliber of each segment of the ureter were evaluated., Results: Renal cortical enhancement was significantly higher in group A (mean ± SD, 145.9 ± 17.5 HU) than group B (120.6 ± 106.3 HU). No significant difference in renal parenchymal enhancement was found with increased imaging delay times. The opacification and maximal caliber of each ureter segment showed no significant difference with different allocation ratios of CM or increased imaging delay times., Conclusion: A split-bolus CTU protocol with a larger CM volume administered at the second injection and an 8-minute imaging delay was the optimal protocol with regard to opacification of the ureter, renal parenchymal enhancement, and shorter examination time.

Objective: The purpose of this study is to evaluate the image quality of split-bolus portal venous phase urography and the potential reduction of radiation dose by using a second-generation dual-source dual-energy CT (DECT) scanner., Materials and Methods: DECT urography was performed in 84 patients. Unenhanced CT was performed 20 minutes after drinking 800 mL of water. The split-bolus protocol consisted of a sequence of injections, as follows: 200 mL of normal saline (2.0 mL/s), 50 mL of contrast medium (2.5 mL/s) at 0 second, 70 mL of contrast medium (2.5 mL/s) at 360 seconds, and a saline flush of 25 mL. The scan was started at 420 seconds. Virtual unenhanced images were reconstructed from contrast-enhanced images. The mean CT density and signal-to-noise ratio (SNR) of the renal parenchyma, vessels, upper urinary tract, normal reference tissues, and tumors were measured for image quantitative analysis. Image quality and opacification of the collecting systems were rated by two radiologists using 3- or 4-point scales., Results: The SNR of all measured sites, except the renal pelvis, showed a statistically significant correlation (p < 0.001) between the true unenhanced and virtual unenhanced images. The overall sensitivity of stone detection was 87.5% (28/32) in virtual unenhanced images. Image quality of the renal parenchyma, arteries, and veins was excellent in 59.5%, 75.0%, and 97.6% of cases, respectively. Opacification of the intrarenal collecting systems, proximal, middle, and distal ureters, and bladder was complete in 92.9%, 83.9%, 78.6%, 77.4%, and 26.2% of patients, respectively. Omitting the unenhanced scan can reduce the mean radiation dose from 15.6 to 6.7 mSv., Conclusion: Portal venous phase split-bolus DECT urography provides sufficient image quality with potential to reduce radiation exposure.

OBJECTIVE. The purpose of this study was to evaluate the yield of repeat CT urography (CTU) in detecting urinary tract malignancies in patients with hematuria. MATERIALS AND METHODS. A review of 5525 patients who underwent CTU between 2000 and 2011 revealed 751 (13.6%) patients who underwent repeat CTU. We excluded 127 patients with more than 3 years between examinations, 409 with nonhematuria indications, and 13 with less than 1 year of follow-up from a negative repeat examination. An additional 54 patients with malignancy diagnosed on the initial evaluation were excluded, leaving 148 patients in the study cohort (77 men and 71 women; mean age, 57 years). Patients were categorized on the basis of the presence or absence of findings suspicious for malignancy on initial CTU reports. Repeat CTU reports were correlated with cystoscopy, pathology, and clinical follow-up to determine the incidence of malignancy. Examinations negative for malignancy were confirmed with at least 1 year of clinical follow-up. CTU examinations of patients diagnosed with malignancy on repeat examination were reviewed by two radiologists in consensus. RESULTS. Initial CTU showed no findings suspicious for malignancy in 103 (70%) of 148 patients; of these, none had malignancy identified on repeat CTU. Among 45 (30%) patients with suspicious initial CTU findings, four malignancies were identified on repeat CTU (8.9%). Three were incidental to the initial suspicious finding; in retrospect, two were present on the initial CTU examination. CONCLUSION. In patients with hematuria, repeat CTU within 3 years is unlikely to show a urinary tract malignancy. These results support currently published guidelines.

Objective: The purpose of this article is to review the utility of CT in diagnosing bladder malignancies, CT protocol options that may improve the conspicuity of bladder tumors, suggestive imaging features, and potential mimics., Conclusion: Although evaluation of the bladder has traditionally been considered purely the realm of cystoscopy, many bladder tumors can be identified with CT. However, diagnosis requires optimization of CT technique and close attention to a number of potentially subtle findings.