Multi-detector row CT urography in the evaluation of hematuria

Detection and characterization of urinary stones using material-specific images derived from contrast-enhanced dual-energy CT urography

OBJECTIVE

To determine the accuracy of material-specific images derived from contrast-enhanced dual-energy CT urography (DECTU) in detecting and measuring urinary stones in comparison with that of unenhanced images and its utility in calcified stone differentiation.

METHODS

105 patients with 202 urinary stones (121 had confirmed composition by infrared spectroscopy) underwent triphasic (unenhanced, portal venous (VP) and excretory phase (EP)) DECTU. Material-specific images were derived in VP and EP with calcium-water, calcium-iodine and CaOxalate_Dihydrate (COD)-Hydroxyapatite (HAP) as basis material pairs. Stone number and size were recorded on unenhanced images and VP and EP material-specific images, where stone densities were also measured. Material densities of calcified stones (pure calcium oxalate [pCaO, n = 34], mixed calcium oxalate [mCaO, n = 14], mixed carbonate phosphate [mCaP, n = 70]) were compared and thresholds for differentiating these stones were determined using receiver operating characteristic analysis.

RESULTS

All 202 urinary stones were detected on the unenhanced, calcium (water) and calcium (iodine) images in VP. While the detection rate was significantly decreased to 58 and 64% using calcium (water) and calcium (iodine) images in EP, respectively (all p < 0.001). Stone sizes measured on calcium (iodine) images in VP was similar to that of unenhanced images (10.6 vs 10.7 mm, p > 0.05). Significant differences in material densities were found among pCaO, mCaO and mCaP on COD(HAP) images with AUC of 0.72-0.74 for differentiating these stones.

CONCLUSION

Material-specific images in VP derived from DECTU allow reliably detecting and measuring urinary tract stones in comparison with unenhanced images and can identify calcified stones with moderate diagnostic performance to provide potential 33% dose reduction.

ADVANCES IN KNOWLEDGE

Material-specific images, especially the calcium (iodine) images in VP allow for reliable detection of urinary stones.Stone size measurement should be performed on the calcium (iodine) images in VP.Material density measurements on COD-HAP (VP) material decomposition images can be used to differentiate among pure calcium oxalate, mixed calcium oxalate and mixed carbonate phosphate stones with AUC of 0.72-0.74.

A retrospective survey to establish institutional diagnostic reference levels for CT urography examinations based on clinical indications: preliminary results

Objective. To establish institutional diagnostic reference levels (IDRLs) based on clinical indications (CIs) for three- and four-phase computed tomography urography (CTU).Methods. Volumetric computed tomography dose index (CTDIvol), dose-length product (DLP), patients' demographics, selected CIs like lithiasis, cancer, and other diseases, and protocols' parameters were retrospectively recorded for 198 CTUs conducted on a Toshiba Aquilion Prime 80 scanner. Patients were categorised based on CIs and number of phases. These groups' 75th percentiles of CTDIvoland DLP were proposed as IDRLs. The mean, median and IDRLs were compared with previously published values.Results. For the three-phase protocol, the CTDIvol(mGy) and DLP (mGy.cm) were 22.7/992 for the whole group, 23.4/992 for lithiasis, 22.8/1037 for cancer, and 21.2/981 for other diseases. The corresponding CTDIvol(mGy) and DLP (mGy.cm) values for the four-phase protocol were 28.6/1172, 30.6/1203, 27.3/1077, and 28.7/1252, respectively. A significant difference was found in CTDIvoland DLP between the two protocols, among the phases of three-phase (except cancer) and four-phase protocols (except DLP for other diseases), and in DLP between the second and third phases (except for cancer group). The results are comparable or lower than most studies published in the last decade.Conclusions. The CT technologist must be aware of the critical dose dependence on the scan length and the applied exposure parameters for each phase, according to the patient's clinical background and the corresponding imaging anatomy, which must have been properly targeted by the competent radiologist. When clinically feasible, restricting the number of phases to three instead of four could remarkably reduce the patient's radiation dose. CI-based IDRLs will serve as a baseline for comparison with CTU practice in other hospitals and could contribute to national DRL establishment. The awareness and knowledge of dose levels during CTU will prompt optimisation strategies in CT facilities.

Computed Tomography Urography: State of the Art and Beyond

Computed Tomography Urography (CTU) is a multiphase CT examination optimized for imaging kidneys, ureters, and bladder, complemented by post-contrast excretory phase imaging. Different protocols are available for contrast administration and image acquisition and timing, with different strengths and limits, mainly related to kidney enhancement, ureters distension and opacification, and radiation exposure. The availability of new reconstruction algorithms, such as iterative and deep-learning-based reconstruction has dramatically improved the image quality and reducing radiation exposure at the same time. Dual-Energy Computed Tomography also has an important role in this type of examination, with the possibility of renal stone characterization, the availability of synthetic unenhanced phases to reduce radiation dose, and the availability of iodine maps for a better interpretation of renal masses. We also describe the new artificial intelligence applications for CTU, focusing on radiomics to predict tumor grading and patients' outcome for a personalized therapeutic approach. In this narrative review, we provide a comprehensive overview of CTU from the traditional to the newest acquisition techniques and reconstruction algorithms, and the possibility of advanced imaging interpretation to provide an up-to-date guide for radiologists who want to better comprehend this technique.

CT of the urinary tract revisited

Computed tomography (CT) of the abdomen is usually appropriate for the initial imaging of many urinary tract diseases, due to its wide availability, fast scanning and acquisition of thin slices and isotropic data, that allow the creation of multiplanar reformatted and three-dimensional reconstructed images of excellent anatomic details. Non-enhanced CT remains the standard imaging modality for assessing renal colic. The technique allows the detection of nearly all types of urinary calculi and the estimation of stone burden. CT is the primary diagnostic tool for the characterization of an indeterminate renal mass, including both cystic and solid tumors. It is also the modality of choice for staging a primary renal tumor. Urolithiasis and urinary tract malignancies represent the main urogenic causes of hematuria. CT urography (CTU) improves the visualization of both the upper and lower urinary tract and is recommended for the investigation of gross hematuria and microscopic hematuria, in patients with predisposing factors for urologic malignancies. CTU is highly accurate in the detection and staging of upper tract urothelial malignancies. CT represents the most commonly used technique for the detection and staging of bladder carcinoma and the diagnostic efficacy of CT staging improves with more advanced disease. Nevertheless, it has limited accuracy in differentiating non-muscle invasive bladder carcinoma from muscle-invasive bladder carcinoma. In this review, clinical indications and the optimal imaging technique for CT of the urinary tract is reviewed. The CT features of common urologic diseases, including ureterolithiasis, renal tumors and urothelial carcinomas are discussed.

Can 3-Phase Computed Tomography Urography Be Used to Characterize Adrenal Nodules? Results in 145 Patients

OBJECTIVE

The aim of the study is to determine whether computed tomography (CT) urography (CTU) can characterize incidental adrenal nodules.

METHODS

This retrospective cohort study was performed at an academic medical center. Patients were identified by free text search of CTU reports that contained the terms "adrenal mass" "adrenal nodule" and "adrenal lesion." Computed tomography urography technique consisted of unenhanced images and postcontrast images obtained at 100 seconds and 15 minutes. The final cohort included 145 patients with 151 adrenal nodules. Nodules were considered lipid-rich adenomas or myelolipomas based on unenhanced imaging characteristics. Absolute and relative washout values were calculated for the remaining nodules, using a cutoff of 60% and 40%, respectively, to diagnose adenomas. Reference standard for lipid-poor adenomas and malignant nodules was histopathology or imaging/clinical follow-up. Mann-Whitney U test was used for comparison of continuous variables, and Fisher exact test was used for categorical variables.

RESULTS

One hundred nodules were lipid-rich adenomas and 3 were myelolipomas. Forty-eight nodules were indeterminate at unenhanced CT, corresponding to 39 lipid-poor adenomas and 9 malignant nodules based on reference standards. Both absolute and relative washout correctly characterized 71% of nodules (34/48), with a sensitivity of 67% and specificity of 89%. Overall, 91% of all adrenal nodules (137/151) were correctly characterized by CTU alone. Lipid-poor adenomas were smaller than malignant nodules (P < 0.01) and were lower in attenuation on unenhanced and delayed images (P < 0.01).

CONCLUSIONS

Adrenal nodules detected at 3-phase CTU can be accurately characterized, potentially eliminating the need for subsequent adrenal protocol CT or magnetic resonance imaging.

CT urography: how to optimize the technique

PURPOSE

Computed tomography urography (CTU) has emerged as the modality of choice for imaging the urinary tract within the past few decades. It is a powerful tool that enables detailed anatomic evaluation of the urinary tract in order to identify primary urothelial malignancies, benign urinary tract conditions, and associated abdominopelvic pathologies. As such, there have been extensive efforts to optimize CTU protocol.

METHODS

This article reviews the published literature on CTU protocol optimization, including contrast bolus timing, dose reduction, reconstruction algorithms, and ancillary practices.

CONCLUSION

There have been many advances in CTU techniques, which allow for imaging diagnosis of a wide spectrum of diseases while minimizing radiation dose and maximizing urinary tract distension and opacification.

Use of Dual-Energy Computed Tomography for Evaluation of Genitourinary Diseases

Since its clinical inception a decade ago, dual-energy computed tomography has expanded the array of computed tomography imaging tools available to the practicing abdominal radiologist. Of note, diagnostic solutions for imaging-based evaluation of genitourinary diseases, foremost kidney calculi and renal tumors characterization, represent the apogee applications of dual-energy computed tomography in abdominal imaging. This article reviews clinical applications of dual-energy computed tomography for the assessment of genitourinary diseases.

Dual-Energy Computed Tomography in Genitourinary Imaging

Reignited by innovations in scanner engineering and software design, dual-energy computed tomography (CT) has come back into the clinical radiology arena in the last decade. Possibilities for noninvasive in vivo characterization of genitourinary disease, especially for renal stones and renal masses, have become the pinnacle offerings of dual-energy CT for body imaging in clinical practice. This article renders a state-of-the-art review on clinical applications of dual-energy CT in genitourinary imaging.

CT Urography for Evaluation of the Ureter

Over the past decade, computed tomographic (CT) urography has emerged as the primary imaging modality for evaluating the urinary tract in various clinical settings, including the initial workup of hematuria. With the widespread implementation of CT urography, it is critical for radiologists to understand normal ureteral anatomy and the varied appearance of pathologic ureteral conditions at CT urography. Pathologic findings at CT urography include congenital abnormalities, filling defects, dilatation, narrowing, and deviations in course. These abnormalities are reviewed, along with the indications for CT urography, current imaging protocols with specific techniques for optimal evaluation of the ureter, and dose reduction strategies.

Haematuria: an imaging guide

This paper discusses the current status of imaging in the investigation of patients with haematuria. The physician must rationalize imaging so that serious causes such as malignancy are promptly diagnosed while at the same time not exposing patients to unnecessary investigations. There is currently no universal agreement about the optimal imaging work up of haematuria. The choice of modality to image the urinary tract will depend on individual patient factors such as age, the presence of risk factors for malignancy, renal function, a history of calculus disease and pregnancy, and other factors, such as local policy and practice, cost effectiveness and availability of resources. The role of all modalities, including conventional radiography, intravenous urography/excretory urography, ultrasonography, retrograde pyelography, multidetector computed tomography urography (MDCTU), and magnetic resonance urography, is discussed. This paper highlights the pivotal role of MDCTU in the imaging of the patient with haematuria and discusses issues specific to this modality including protocol design, imaging of the urothelium, and radiation dose. Examination protocols should be tailored to the patient while all the while optimizing radiation dose.

In search of a consensus: evaluation of the patient with hematuria in an era of cost containment

OBJECTIVE

The purpose of this article is to describe the current consensus guidelines for nonimaging triage and ultimate preferred imaging approach for the patient with unexplained hematuria.

CONCLUSION

Numerous consensus guidelines from varying societies have outlined preferred imaging pathways for the patient with unexplained urologic causes of hematuria. Future guidelines will need to take into account disease prevalence, radiation considerations, and cost.

When the non-contrast-enhanced phase is unnecessary in abdominal computed tomography scans? A retrospective analysis of 244 cases

Objective: To evaluate the necessity of the non contrast-enhanced phase in abdominal computed tomography scans. Materials and Methods: A retrospective, cross-sectional, observational study was developed, evaluating 244 consecutive abdominal computed tomography scans both with and without contrast injection. Initially, the contrast-enhanced images were analyzed (first analysis). Subsequently, the observers had access to the non-contrast-enhanced images for a second analysis. The primary and secondary diagnoses were established as a function of the clinical indications for each study (such as tumor staging, acute abdomen, investigation for abdominal collection and hepatocellular carcinoma, among others). Finally, the changes in the diagnoses resulting from the addition of the non-contrast-enhanced phase were evaluated. Results: Only one (0.4%; p > 0.999; non-statistically significant) out of the 244 reviewed cases had the diagnosis changed after the reading of non-contrast-enhanced images. As the secondary diagnoses are considered, 35 (14%) cases presented changes after the second analysis, as follows: nephrolithiasis (10%), steatosis (3%), adrenal nodule (0.7%) and cholelithiasis (0.3%). Conclusion: For the clinical indications of tumor staging, acute abdomen, investigation of abdominal collections and hepatocellular carcinoma, the non-contrast-enhanced phase can be excluded from abdominal computed tomography studies with no significant impact on the diagnosis.

Performance of computed tomographic urography for the detection of bladder tumors in patients with microscopic hematuria

OBJECTIVE

Our objective was to evaluate the sensitivity, specificity, predictive value, and accuracy of computed tomographic urography for the detection of bladder tumors in patients with microscopic hematuria.

MATERIAL AND METHODS

Patients with microscopic hematuria initially evaluated with computed tomography and cystoscopy from January 2006 to December 2009 were evaluated. Computed tomography detecting a bladder lesion suspicious of malignancy was considered positive. Cystoscopy was classified as positive when a lesion requiring biopsy or resection was found. Performance characteristics of computed tomography were determined by comparing with cystoscopic and pathological findings.

RESULTS

A total of 112 patients were eligible for analysis. Seven tumors were found on cystoscopy; of these, 2 were correctly diagnosed by computed tomography and 5 were missed. An additional case was considered erroneously positive. The results are a sensitivity of 29%, specificity of 99%, positive predictive value of 67%, negative predictive value of 95%, and accuracy of 95%.

CONCLUSIONS

Although computed tomography has a high specificity its sensitivity is limited. For this reason conventional cystoscopy should be considered the standard for bladder evaluation of patients with microscopic hematuria.

Quando a fase de equilíbrio pode ser suprimida nos exames de tomografia computadorizada de abdome?

OBJETIVO: Avaliar a necessidade de realização da fase de equilíbrio nos exames de tomografia computadorizada de abdome. MATERIAIS E MÉTODOS: Realizou-se estudo retrospectivo, transversal e observacional, avaliando 219 exames consecutivos de tomografia computadorizada de abdome com contraste intravenoso, realizados num período de três meses, com diversas indicações clínicas. Para cada exame foram emitidos dois pareceres, um avaliando o exame sem a fase de equilíbrio (primeira análise) e o outro avaliando todas as fases em conjunto (segunda análise). Ao final de cada avaliação, foi estabelecido se houve mudança nos diagnósticos principais e secundários, entre a primeira e a segunda análise. Foi utilizada a extensão do teste exato de Fisher para avaliar a modificação dos diagnósticos principais (p < 0,05 como significante). RESULTADOS: Entre os 219 casos avaliados, a supressão da fase de equilíbrio provocou alteração no diagnóstico principal em apenas um exame (0,46%; p > 0,999). Com relação aos diagnósticos secundários, cinco exames (2,3%) foram modificados. CONCLUSÃO: Para indicações clínicas como estadiamento tumoral, abdome agudo e pesquisa de coleção abdominal, a fase de equilíbrio não acrescenta contribuição diagnóstica expressiva, podendo ser suprimida dos protocolos de exame.

Calyceal diverticulum - a mimic of different pathologies on multiple imaging modalities

Calyceal diverticula are outpouchings of a renal calyx. Often found incidentally on radiological imaging, they are generally benign and usually asymptomatic, although complications include infection and stone formation. More importantly, calyceal diverticula may mimic other potentially more serious pathology on imaging, such as renal tumour or abscess on ultrasound or computed tomography and even rib metastasis on bone scintigraphy. We present a case of a patient with a calyceal diverticulum found incidentally on imaging, in which the diverticulum is demonstrated on ultrasound, computed tomography, intravenous urogram and bone scintigraphy, and discuss the potential differential diagnoses that need to be excluded in this condition.

Single-phase dual-energy CT urography in the evaluation of haematuria

AIM

To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic-excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan.

MATERIALS AND METHODS

Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic-excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated.

RESULTS

The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%.

CONCLUSION

Single-phase DECT urography with synchronous nephrographic-excretory phase enhancement represents an accurate "all-in-one'' approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol.

Split-bolus CT-urography using dual-energy CT: feasibility, image quality and dose reduction

PURPOSE

To prospectively evaluate the feasibility of dual-energy (DE) split-bolus CT-urography (CTU) and the quality of virtual non-enhanced images (VNEI) and DE combined nephrographic-excretory phase images (CNEPI), and to estimate radiation dose reduction if true non-enhanced images (TNEI) could be omitted.

PATIENTS AND METHODS

Between August and September 2011, 30 consecutive patients with confirmed or suspected urothelial cancer or with hematuria underwent DE CT. Single-energy TNEI and DE CNEPI were obtained. VNEI was reconstructed from CNEPI. Image quality of CNEPI and VNEI was evaluated using a 5-point scale. The attenuation of urine in the bladder on TNEI and VNEI was measured. The CT dose index volume (CTDI (vol)) of the two scans was recorded.

RESULTS

The mean image quality score of CNEPI and VNEI was 4.7 and 3.3, respectively. The mean differences in urine attenuation between VNEI and TNEI were 14±15 [SD] and -16±29 in the anterior and posterior parts of the bladder, respectively. The mean CTDI (vol) for TNEI and CNEPI was 11.8 and 10.9 mGy, respectively. Omission of TNEI could reduce the total radiation dose by 52%.

CONCLUSION

DE split-bolus CTU is technically feasible and can reduce radiation exposure; however, an additional TNEI scan is necessary when the VNEI quality is poor or quantitative evaluation of urine attenuation is required.

Detection of urothelial tumors: comparison of urothelial phase with excretory phase CT urography--a prospective study

PURPOSE

To compare contrast material-enhanced computed tomographic (CT) urography 60 seconds after injection of contrast material (urothelial phase [UP]) after intravenous administration of a diuretic with the standard 5-minute delayed excretory phase (EP) in a high-risk population for upper tract tumors.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. Eighty CT urographic examinations in 77 patients known to have or at high risk for urothelial malignancy were included. After intravenous administration of a diuretic, dual-phase CT urography was performed at 60 seconds (UP) and 5 minutes (EP) after intravenous administration of contrast material. Two experienced abdominal radiologists independently interpreted each phase more than 1 month apart to minimize recall bias. Urinary tract distention and location and size of all lesions suspected of being urothelial tumors were recorded. Standard of reference was obtained from prospective study interpretation and surgical histopathologic findings. Generalized estimating equations for logistic regression were used to compare performance measures and adjust for the correlation of repeated measures within patients.

RESULTS

There were 23 upper and 61 lower urinary tract tumors confirmed in 15 and 32 patients, respectively. For detection of bladder tumors, there was higher sensitivity for the UP than the EP (89.3% [109 of 122] vs 70.5% [86 of 122], respectively; P<.0001). For detection of upper tract tumors, there was higher sensitivity for the UP than the EP (82.6% [38 of 46] vs 69.6% [32 of 46], respectively; P=.0194). Distention of all upper urinary tract segments was better during the EP than the UP (P<.0001).

CONCLUSION

UP CT urography after injection of a diuretic has a higher lesion detection rate than the EP for both upper and lower urinary tract tumors, which suggests its possible use as a single-phase protocol for evaluation of the entire urinary tract in patients at high risk for urothelial tumors.

Urothelial carcinoma of the bladder: definition, treatment and future efforts

The identification of patients with high-risk bladder cancer is important for the timely and appropriate treatment of this lethal disease. The understanding of the natural history of bladder cancer has improved; however, the criteria used to define high-risk disease and the relevant treatment strategies have remained the same for the past several decades, despite multiple large, randomized, prospective clinical trials that have evaluated the use of intravesical, surgical and systemic therapies. The genetic signature of high-risk bladder cancer has been a focus of investigation and has led to the discovery of potential molecular targets for disease identification, risk stratification and therapy. These advances, combined with a comprehensive risk assessment profile that incorporates available pathological and clinical characteristics, might improve the diagnosis and treatment of patients with bladder cancer.

Hematuria evaluation with MDCT urography: is a contrast-enhanced phase needed when calculi are detected in the unenhanced phase?

OBJECTIVE

The purpose of this study was to assess the added utility of the contrast-enhanced phase of MDCT urography (MDCTU) when urinary tract calculi are detected in the preliminary unenhanced phase.

MATERIALS AND METHODS

A computer search of CT reports with the term "hematuria" yielded the records of 1209 patients who had undergone MDCTU. The reports of 286 MDCTU examinations in which urinary tract calculi were detected were identified, and two blinded abdominal radiologists reviewed the images to find a second source of hematuria. The unenhanced images were reviewed first, and the findings were compared with those on the subsequent contrast-enhanced images. The aggregate findings of the 286 examinations in which calculi were present were compared with those of the 923 examinations in which calculi were absent. The follow-up diagnosis was based on histopathologic findings, findings at urologic procedures, or the imaging diagnosis.

RESULTS

In 119 of the 1209 patients (10%), 127 lesions other than urinary tract calculi were identified as possible sources of hematuria. Eighty-two lesions were diagnosed in 77 patients (6%) at follow-up evaluation. A second source of hematuria was found in 19 of the 286 examinations (7%) with calculi compared with 58 of the 923 examinations (6%) without calculi (p = 0.828), and contrast was needed to make a specific diagnosis in 16 of the 19 examinations (84%).

CONCLUSION

When urinary tract calculi are identified at MDCTU, the rate of detection of other potential causes of hematuria is not different from that in MDCTU examinations without calculi. The contrast-enhanced portion of the MDCTU examination is needed even if calculi are seen because important pathologic changes are diagnosed only after the contrast-enhanced phase.

Assessment and characterisation of common renal masses with CT and MRI

Objective

Owing to the widespread use of abdominal imaging studies the detection rate of solid renal masses has increased, and an accurate characterisation of imaging features of renal masses has become more essential for case management.

Method and results

MR imaging (MRI) and computed tomography (CT) are frequently used modalities for detection and differentiation of renal masses. This article gives a review of imaging characteristics of benign and malignant renal masses, discussing their appearance in CT and MR imaging. Advanced MR techniques like diffusion-weighted imaging and apparent diffusion coefficient (ADC) mapping, which have shown promising results in the differentiation between benign and malignant renal lesions, will be introduced.

Conclusion

MRI and CT are useful in the characterisation and estimation of the prognosis for renal masses.

CT urography in the urinary bladder: to compare excretory phase images using a low noise index and a high noise index with adaptive noise reduction filter

BACKGROUND

Although CT urography (CTU) is widely used for the evaluation of the entire urinary tract, the most important drawback is the radiation exposure.

PURPOSE

To evaluate the effect of a noise reduction filter (NRF) using a phantom and to quantitatively and qualitatively compare excretory phase (EP) images using a low noise index (NI) with those using a high NI and postprocessing NRF (pNRF).

MATERIAL AND METHODS

Each NI value was defined for a slice thickness of 5 mm, and reconstructed images with a slice thickness of 1.25 mm were assessed. Sixty patients who were at high risk of developing bladder tumors (BT) were divided into two groups according to whether their EP images were obtained using an NI of 9.88 (29 patients; group A) or an NI of 20 and pNRF (31 patients; group B). The CT dose index volume (CTDI(vol)) and the contrast-to-noise ratio (CNR) of the bladder with respect to the anterior pelvic fat were compared in both groups. Qualitative assessment of the urinary bladder for image noise, sharpness, streak artifacts, homogeneity, and the conspicuity of polypoid or sessile-shaped BTs with a short-axis diameter greater than 10 mm was performed using a 3-point scale.

RESULTS

The phantom study showed noise reduction of approximately 40% and 76% dose reduction between group A and group B. CTDI(vol) demonstrated a 73% reduction in group B (4.6 ± 1.1 mGy) compared with group A (16.9 ± 3.4 mGy). The CNR value was not significantly different (P = 0.60) between group A (16.1 ± 5.1) and group B (16.6 ± 7.6). Although group A was superior (P < 0.01) to group B with regard to image noise, other qualitative analyses did not show significant differences.

CONCLUSION

EP images using a high NI and pNRF were quantitatively and qualitatively comparable to those using a low NI, except with regard to image noise.

Blind-ending branch of a bifid ureter: multidetector CT imaging findings

A bifid ureter with a blind-ending branch is a rare congenital anomaly. Although typically found incidentally, this anomaly can be symptomatic and radiologists should be aware of this important variant. To our knowledge, there has been no previous report of this anomaly as seen on multidetector CT urography. We present a patient with haematuria and review the clinical significance, radiological findings and embryological aetiology of this anomaly.

Utility of CT Scan in detection of melamine--associated urinary stones

OBJECTIVE

To detail the utility of CT scan in detection of urinary stones induced by melamine tainted formula.

MATERIAL AND METHODS

A total of 1062 children fed with melamine-contaminated infant formula were screened for urinary stones in our institute from September through December 2008. Ultrasonography of the urinary tract system was performed in all these children. If the children with suspected stones or severe obstruction were presented after ultrasound examination, the multi-detector row CT urographic examination was advocated subsequently.

RESULTS

Ultrasound examination in combination with multi-detector row CT urography could increase the diagnostic rate from 3.4% (36/1062) by ultrasound examination alone to 4.6% (49/1062).

CONCLUSIONS

The specificity and sensitivity of the multi-detector row CT urographic examination is higher than ultrasonography.

[Intravenous urography is died. Long live the computerized tomography!]

Very important changes have happened in the field of the genitourinary image during the last half of the 20th century, so that for most of the historical intravenous urography indications, nowadays the computerized tomography (CT) is technique of choice. The aim of this report is to perform an update in the correct use of the imaging techniques in the adult-related most frequent urological pathology, including: urolithiasis, haematuria, infections, tumours, surgery follow-up and pyelectasis, specially focused in CT. A brief historical review of the urological imaging techniques is performed, emphasizing the physical principles. In the second part, the role played by plain X-ray, ultrasound, CT and MR in the different urological pathologies are reviewed, discussing the sensibility and specificity of each technique. A brief reflection is finally carried out over of the radiation doses.

Kidney and urinary tract imaging: triple-bolus multidetector CT urography as a one-stop shop--protocol design, opacification, and image quality analysis

PURPOSE

To retrospectively evaluate renal, vascular, and urinary tract visualization following a single postcontrast multidetector computed tomographic (CT) urographic sequence performed with three limited-volume bolus injections.

MATERIALS AND METHODS

The institutional review board approved this retrospective study. Patient informed consent was waived. Triple-bolus multidetector CT urography was performed in 110 patients. Triple-bolus protocol consisted of 30 mL of contrast material at 2 mL/sec at 0 seconds, 50 mL at 1.5 mL/sec at 435 seconds, 65 mL at 3 mL/sec at 488 seconds, with total abdominal scanning time of 510 seconds. Two independent readers rated urinary tract opacification and qualitatively and quantitatively assessed renal parenchymal and vascular contrast enhancement. Upper urinary tract (UUT) distention was measured by one reader. Interobserver agreement was assessed by using kappa statistics.

RESULTS

Complete opacification of the intrarenal collecting system and proximal ureter was achieved in 91% (184 of 202) (kappa = 0.62) and 82% (166 of 202) (kappa = 0.94) of segments, respectively. The distal ureter was not opacified in 21% of the cases (kappa = 0.92), and the bladder was not opacified in 20% of the cases. Mean distention was higher for proximal (3.9 mm) than for distal (3.7 mm) segments. Image quality of renal parenchymal enhancement was excellent in 76% of cases. Arteries showed better contrast enhancement than veins (excellent rating in 89% vs 59% of the cases). Radiation dose calculated for triple-bolus acquisition was 9.8 mSv.

CONCLUSION

Triple-bolus multidetector CT urography is a dose-efficient protocol acquiring corticomedullary-nephrographic-excretory and vascular enhancement phases in a single acquisition and provides sufficient opacification and distention of the UUT. Simultaneously, adequate image quality of renal parenchyma and vascular anatomy is achieved.

Multidetector computerized tomography urography is more accurate than excretory urography for diagnosing transitional cell carcinoma of the upper urinary tract in adults with hematuria

PURPOSE

It is debatable whether traditionally used excretory urography or the recently introduced multidetector computerized tomography urography is more accurate for diagnosing upper urinary tract transitional cell carcinoma. We compared accuracy measures of both methods for diagnosing upper urinary tract transitional cell carcinoma in adult patients with hematuria.

MATERIALS AND METHODS

We retrospectively analyzed consecutive adult patients with hematuria undergoing excretory urography and multidetector computerized tomography urography before any surgery, intervention or treatment from April 2004 to December 2006 in our hospital. The presence of upper urinary tract transitional cell carcinoma on excretory urography and multidetector computerized tomography urography was reviewed independently by 2 uroradiologists who were blinded to clinical information and other imaging results. Final diagnosis of upper urinary tract transitional cell carcinoma was confirmed by histological results. Measures of the diagnostic accuracy of excretory urography and multidetector computerized tomography urography for upper urinary tract transitional cell carcinoma were calculated and compared with reference to the final diagnosis.

RESULTS

Of 34 men and 26 women with hematuria (mean age 60.73 +/- 12.95 years) 19 (31.7%) had a final diagnosis of 24 upper urinary tract transitional cell carcinomas. The sensitivity, specificity and accuracy of excretory urography were 0.750, 0.860 and 0.849, respectively. In contrast, the sensitivity, specificity and accuracy of multidetector computerized tomography urography were 0.958, 1.000 and 0.996, respectively. Overall the area under the receiver operating characteristic curve for multidetector computerized tomography urography was significantly larger than that for excretory urography (0.978 vs 0.815, p = 0.005).

CONCLUSIONS

Multidetector computerized tomography urography is more sensitive, specific and accurate than excretory urography in the diagnosis of upper urinary tract transitional cell carcinoma in adult patients with hematuria. Therefore, multidetector computerized tomography urography rather than excretory urography should be the first choice noninvasive imaging modality for diagnosing upper urinary tract transitional cell carcinoma.

Diagnosis of acute appendicitis with sliding slab ray-sum interpretation of low-dose unenhanced CT and standard-dose i.v. contrast-enhanced CT scans

OBJECTIVE

The purpose of this study was to compare low-dose unenhanced CT with standard-dose i.v. contrast-enhanced CT in the diagnosis of appendicitis.

MATERIALS AND METHODS

Two hundred seven adults with suspected appendicitis underwent CT with mean effective doses of both 4.2 and 8.0 mSv. Two radiologists retrospectively reviewed thin-section images by sliding a 5-mm-thick ray-sum slab. They rated the likelihood of appendicitis and appendiceal visualization on 5- and 3-point scales, respectively, and proposed alternative diagnoses. Likelihood > or = 3 was considered a positive diagnosis. Receiver operating characteristics analysis, the McNemar test, and the Wilcoxon's signed-rank test were used.

RESULTS

Seventy-eight patients had appendicitis. The values of the area under the receiver operating characteristics curve were 0.98 for the low-dose unenhanced acquisition and 0.97 for the standard-dose contrast-enhanced acquisition for reader 1 (95% CI for the difference, -0.02 to 0.03) and 0.99 and 0.98 (-0.02 to 0.02) for reader 2. Sensitivity was 98.7% for low-dose unenhanced CT and 100% for standard-dose contrast-enhanced CT for reader 1 (p = 1.00) and 100% for both techniques for reader 2. Specificity was 95.3% and 93.0% (p = 0.25) and 96.9% and 96.9%. The interpretation was indeterminate (score 3) in 0.5% and 1.4% of cases for reader 1 (p = 0.63) and 0.5% and 0% for reader 2 (p = 1.00). A normal appendix was not visualized in 5.4% and 3.9% of cases by reader 1 (p = 0.63) and 3.9% and 2.3% of cases by reader 2 (p = 0.50). None of the patients whose appendix was not visualized had appendicitis. Diagnostic confidence, visualization score for a normal appendix, and correct alternative diagnosis tended to be compromised with use of low-dose unenhanced CT, showing a significant difference for a reader's confidence in the diagnosis of appendicitis (p = 0.004). The two techniques were comparable in the diagnosis of appendiceal perforation.

CONCLUSION

Low-dose unenhanced CT is potentially useful in the diagnosis of appendicitis.

[Diagnostic procedures in upper urinary tract urothelial carcinoma]

Upper urinary tract transitional cell carcinomas represent 5-6% of all urothelial carcinomas. Macroscopic hematuria is the most common symptom. The diagnostic algorithm contains medical history, clinical investigation, cystoscopy, urinary cytology, ultrasound and intravenous urography. When suspected, a complementary retrograde pyeloureterography with collecting selective urinary cytology is conducted. When radiological findings are doubted or when conservative treatment is planned, an ureterorenoscopy for biopsy of the suspected area is indicated. Computed tomography and magnetic resonance tomography is used to define the local extension of invasive tumors and to detect metastases. The use of urinary markers in the diagnosis of upper urinary tract urothelial carcinoma has to be evaluated in prospective trials.

[Imaging capabilities in upper urothelial malignancies differentiation]

Aim of our study is to analyze sensitivity and specificity of imaging procedures in characterization upper urothelial malignancies, according to algorithm suggested by American Urology Association.

MATERIAL AND METHODS

We analyzed 242 patients with kidney tumor masses who had been operated during 2006/2007 at Urological clinic in Belgrade. Due to pathohistological exam 210 patients had kidney parenchyma and 32 patients upper urothelial kidney tumor.

RESULTS

According to tumor stage, computed tomography was sufficient and definitive diagnostic tool concerning both renal epithelial and upper urothelial malignancy. Only in four cases 1.60% (4/242; CT in 3/4, MRI 1/4) preoperative site of origin was different from histopathology findings. This mislead to inappropriate surgery plan.

CONCLUSION

Familiarity with limitations and capabilities of imaging modalities is crucial for appropriate diagnosis. It should respect algorithm but has to be individual adapted.