Small (< or = 3 cm) renal masses: correlation of spiral CT features and pathologic findings

Imaging of Solid Renal Masses

The increase in serendipitous detection of solid renal masses on imaging has not resulted in a reduction in mortality from renal cell carcinoma. Consequently, efforts for improved lesion characterization have been pursued and incorporated into management algorithms for distinguishing clinically significant tumors from those with favorable histology or benign conditions. Although diagnostic imaging strategies have evolved for optimized lesion detection, distinction between benign tumors and both indolent and aggressive malignant neoplasms remain an important diagnostic challenge. Recent advances in cross-sectional imaging have expanded the role of these tests in the noninvasive characterization of solid renal tumors.

Determination of single-kidney glomerular filtration rate (GFR) with CT urography versus renal dynamic imaging Gates method

OBJECTIVES

To present a single-kidney CT-GFR measurement and compare it with the renal dynamic imaging Gates-GFR.

MATERIALS AND METHODS

Thirty-six patients with hydronephrosis referred for CT urography and 99mTc-DTPA renal dynamic imaging were prospectively included. Informed consent was obtained from all patients. The CT urography protocol included non-contrast, nephrographic, and excretory phase imaging. The total CT-GFR was calculated by dividing the CT number increments of the total urinary system between the nephrographic and excretory phase by the products of iodine concentration in the aorta and the elapsed time, then multiplied by (1- Haematocrit). The total CT-GFR was then split into single-kidney CT-GFR by a left and right kidney proportionality factor. The results were compared with single-kidney Gates-GFR by using paired t-test, correlation analysis, and Bland-Altman plots.

RESULTS

Paired difference between single-kidney CT-GFR (45.02 ± 13.91) and single-kidney Gates-GFR (51.21 ± 14.76) was 6.19 ± 5.63 ml/min, p<0.001, demonstrating 12.1% systematic underestimation with ±11.03 ml/min (±21.5%) measurement deviation. A good correlation was revealed between both measurements (r=0.87, p<0.001).

CONCLUSION

The proposed single-kidney CT-GFR correlates and agrees well with the reference standard despite a systematic underestimation, therefore it could be a one-stop-shop for evaluating urinary tract morphology and split renal function.

KEY POINTS

• A new CT method can assess split renal function • Only using images from CT urography and the value of haematocrit • A one-stop-shop CT technique without additional radiation dose.

Renal cell carcinoma attenuation values on unenhanced CT: importance of multiple, small region-of-interest measurements

OBJECTIVE

Since it has been suggested that benign renal cysts can be diagnosed at unenhanced CT on the basis of homogeneity and attenuations of 20 HU or less, we determined the prevalence of renal cell carcinomas (RCCs) with these characteristics using two different methods of measuring attenuation.

MATERIALS AND METHODS

After IRB approval, two radiologists obtained unenhanced attenuation values of 104 RCCs (mean size 5.6 cm) using a single, large region of interest (ROI), two-thirds the size of the mass. They were then determined if the masses appeared heterogeneous. Of RCCs measuring 20 HU or less, those which appeared homogeneous were re-measured with multiple (6 or more), small (0.6 cm² or smaller) ROIs dispersed throughout the lesion. Masses with attenuations 20 HU or less were compared to those with masses with HU greater than 20 for any differences in demographic data.

RESULTS

Of 104 RCCS, 24 RCC had HU less than 20 using a large ROI. Of these, 21 appeared heterogeneous and 3 appeared homogeneous. Using multiple small ROIs, these three RCCs revealed maximum attenuation values above 20 HU (Range: 26-32 HU). A greater portion of RCCs measuring 20 HU or less using a large ROI were clear cell sub-type. There were no other differences.

CONCLUSIONS

Renal cell carcinoma can measure 20 HU or less at unenhanced CT when a single large ROI is used. While most appear heterogeneous, some may appear homogeneous, but will likely reveal attenuations greater than 20 HU when multiple, small ROIs are used. This knowledge may prevent some RCCs from being misdiagnosed as cysts on unenhanced CT.

Image-guided ablation of renal cell carcinoma

This review article aims to provide an overview of image-guided ablation of renal cell carcinoma (RCC) since it was first introduced in 1998. This will cover the background and rationale behind its development; an overview of the evidence for current thermal technology, such as heat-based, e.g., radiofrequency ablation (RFA), microwave ablation (MWA), and cold-based energies, e.g., cryoablation used; and summarise the published evidence regarding its treatment efficacy and oncological outcome. In addition, it aims to provide an insight into the potential role of the new non-thermal ablative technology, e.g., irreversible electroporation (IRE)/Nanoknife in image-guided ablation of RCC, as well as areas of challenge that will require further research and clinical evaluation to ensure delivery of a quality patient-centred interventional oncology (IO) service in image-guided ablation of RCC.

Imaging of Solid Renal Masses

Detection of solid renal masses has increased, although it has not resulted in significant mortality reduction from renal cell carcinoma. Efforts for improved lesion characterization have been pursued and incorporated in management algorithms, in order to distinguish clinically significant tumors from favorable or benign conditions. Concurrently, imaging methods have produced evidence supporting their role as useful tools not only in lesion detection but also characterization. In addition, newer modalities, such as contrast-enhanced ultrasonography, and advanced applications of MR imaging, are being investigated. This article reviews the current role of different imaging methods in the characterization of solid renal masses.

ACR Appropriateness Criteria indeterminate renal mass

Renal masses are increasingly detected in asymptomatic individuals as incidental findings. An indeterminate renal mass is one that cannot be diagnosed confidently as benign or malignant at the time it is discovered. CT, ultrasonography, and MRI of renal masses with fast-scan techniques and intravenous (IV) contrast are the mainstays of evaluation. Dual-energy CT, contrast-enhanced ultrasonography, PET/CT, and percutaneous biopsy are all technologies that are gaining traction in the characterization of the indeterminate renal mass. In cases in which IV contrast cannot be used, whether because of IV contrast allergy or renal insufficiency, renal mass classification with CT is markedly limited. In the absence of IV contrast, ultrasonography, MRI, and biopsy have some advantages. Owing to the low malignant and metastatic potential of small renal cell carcinomas (≤4 cm in diameter), active surveillance is additionally emerging as a diagnostic strategy for patients who have high surgical risk or limited life expectancy. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and application by the panel of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Advances of multidetector computed tomography in the characterization and staging of renal cell carcinoma

Renal cell carcinoma (RCC) accounts for approximately 90%-95% of kidney tumors. With the widespread use of cross-sectional imaging modalities, more than half of RCCs are detected incidentally, often diagnosed at an early stage. This may allow the planning of more conservative treatment strategies. Computed tomography (CT) is considered the examination of choice for the detection and staging of RCC. Multidetector CT (MDCT) with the improvement of spatial resolution and the ability to obtain multiphase imaging, multiplanar and three-dimensional reconstructions in any desired plane brought about further improvement in the evaluation of RCC. Differentiation of RCC from benign renal tumors based on MDCT features is improved. Tumor enhancement characteristics on MDCT have been found closely to correlate with the histologic subtype of RCC, the nuclear grade and the cytogenetic characteristics of clear cell RCC. Important information, including tumor size, localization, and organ involvement, presence and extent of venous thrombus, possible invasion of adjacent organs or lymph nodes, and presence of distant metastases are provided by MDCT examination. The preoperative evaluation of patients with RCC was improved by depicting the presence or absence of renal pseudocapsule and by assessing the possible neoplastic infiltration of the perirenal fat tissue and/or renal sinus fat compartment.

Unenhanced CT for the detection of renal cell carcinoma: effect of tumor size and contour type

PURPOSE

To evaluate effect of tumor size and contour type for the detection of renal cell carcinoma (RCC) on unenhanced CT.

METHODS

This retrospective institutional review board approved study that includes 111 patients with RCC and 100 patients without RCC who underwent unenhanced CT. Two readers performed a blinded and independent review of the presence of RCC on unenhanced CT. The area under the receiver operating characteristic curves (AUC) was compared by tumor size (<3 cm: small, or ≥3 cm: large) and contour type (endophytic, mesophytic, or exophytic).

RESULTS

For tumor size, the AUC for small RCC (0.70 and 0.78, for reader 1 and reader 2) was significantly lower than that for large RCC (0.97 and 0.99, for reader 1 and reader 2) (p < 0.001). As for contour type of tumor, the AUC for endophytic RCC (0.60 and 0.71, for reader 1 and reader 2) was significantly lower than that for mesophytic RCC (0.95 and 0.98, for reader 1 and reader 2) and exophytic RCC (0.98 and 0.99, reader 1 and reader 2) (p < 0.001).

CONCLUSION

On unenhanced CT, tumor size and contour type can affect the detection of RCC. While most large or exophytic RCC can be easily detected, the detection of small and endophytic RCC is highly limited.

Radiofrequency ablation (RFA) of renal cell carcinoma (RCC): experience in 200 tumours

Objectives

Patients and Methods

Results

Conclusions

Development of renal cell carcinoma (RCC) diagnostics and impact on prognosis

OBJECTIVE

To evaluate imaging methods and prognoses between small renal cell carcinomas (RCCs) and larger tumours according to the era of diagnostics.

PATIENTS AND METHODS

In all, 784 consecutive patients diagnosed with RCC between 1964 and 1997 at the Pirkanmaa Hospital District in Finland were included. Patients were divided into two groups: tumours of ≤3.0 and >3.0 cm in diameter. Prognosis was analysed according to the era of diagnostics: (i) pre-computed tomography (CT) and pre-ultrasound (US), (ii) US era and (iii) CT era.

RESULTS

Small tumours became more common: in the pre-CT and pre-US era, only 4.4% of tumours were small; however, in the CT era 16% were small tumours. More diagnostic methods were used in studying small tumours. CT proved to be the most reliable method, although it was actually better at diagnosing large tumours. Relapses occurred less frequently among patients with small tumours; more than half of the tumours that developed distant metastases (16.0%) already evinced them at the time of diagnosis. There were no relapses after 14 years of follow-up among small tumours, whereas large tumours relapsed within that time. RCC was the cause of death in 14.9% of patients with small tumours vs 50.7% with large tumours. The best prognosis was among patients with small tumours diagnosed with CT.

CONCLUSION

Among patients with small tumours, prognosis has improved along with better diagnostics, although some showed relapse during a surveillance period of up to 14 years.

Percutaneous radiofrequency ablation of small renal tumours in patients with a single functioning kidney: long-term results

OBJECTIVES

To evaluate the long-term results of percutaneous radiofrequency ablation (RFA) of small renal tumours in patients with a single functioning kidney (SFK).

METHODS

This is a single-centre prospective study. Patients with an SFK and a tumour smaller than 3.5 cm, treated with RFA over a 7.5-year period, were included. Nineteen consecutive patients (12 male), aged between 33 and 83 years (mean 61.4), were treated for 23 lesions. Primary endpoints were technical success and tumour recurrence rate. Secondary endpoints were the deterioration of renal function and overall survival rate.

RESULTS

The mean follow-up was 56.1 months (range 36-102). Primary technical success was 100 %. There were no major peri-procedural complications. In two cases, minor complications occurred. There was no significant difference between the baseline glomerular filtration rate (GFR) and GFR at 3, 12 and 24 months post-procedure. In four lesions (17 %), recurrence was detected and an additional RFA session was performed. None of the patients developed renal failure during their lifetime. Three of the patients died because of other reasons.

CONCLUSIONS

Percutaneous RFA of small renal tumours in patients with an SFK offers very satisfactory long-term results regarding preservation of renal function, local tumour control and overall survival.

KEY POINTS

• Tumour in a single functioning kidney requires minimally invasive treatment. • Radiofrequency ablation plays an established role in managing small renal tumours. • Long-term results of radiofrequency ablation have shown satisfactory local tumour control. • Long-term results have also shown that renal function may be preserved.

Angiomyolipoma with minimal fat: differentiation from papillary renal cell carcinoma by helical CT

AIM

To evaluate whether helical computed tomography (CT) images can be used to differentiate angiomyolipomas (AMLs) with minimal fat from papillary renal cell carcinomas (PRCCs) based on their morphological characteristics and enhancement features.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board. Informed consent was waived. Forty-four patients (21 with AMLs with minimal fat and 23 with PRCCs) who underwent enhanced helical CT before total or partial nephrectomy were included. Two radiologists, who were blinded to the histopathology results, read the CT images and recorded the attenuation value, morphological characteristics, and enhancement features of the tumours, which were subsequently evaluated. An independent samples t-test, χ(2) test, and rank sum test were performed between the tumours. The predictive value of a CT finding was determined by multivariate logistic regression analysis.

RESULTS

AML with minimal fat had an apparent female prevalence (p < 0.01). Intra-tumoural vessels were noted in 11 cases of AML with minimal fat and three PRCC cases (p < 0.01). The unenhanced attenuation characteristic was significantly different between the two diseases (p < 0.001). The absolute attenuation values (AAVs) and the corrected attenuation values (CAVs) of the AML with minimal fat group of unenhanced and two phases of enhanced images were greater compared with that of the PRCC group (p < 0.05). After contrast medium injection, the tumour enhancement value (TEV) of the AML with minimal fat group in the corticomedullary phase was greater than that of the PRCC group (p < 0.01). Most cases of both tumour types demonstrated early enhancement characteristics; the enhancement value of the AML with minimal fat group was greater compared with that of the PRCC group (p < 0.01). The unenhanced attenuation characteristic, intra-tumoural vessels, and CAVs of unenhanced and early excretory phase scans were valuable parameters to differentiate between AML with minimal fat and PRCC tumours by multivariate logistic regression analysis (p < 0.05 for all).

CONCLUSION

The unenhanced attenuation characteristic, intra-tumoural vessels, and the attenuation values of unenhanced and early excretory phase scans are valuable parameters in differentiating AML with minimal fat from PRCC at CT.

Renal cell carcinoma: value of multiphase MDCT with multiplanar reformations in the detection of pseudocapsule

OBJECTIVE

The purpose of this study was to assess the diagnostic performance of four-phase (unenhanced, arterial, portal, and nephrographic-excretory) MDCT with multiplanar reformations in the detection of pseudocapsule of renal cell carcinoma (RCC).

MATERIALS AND METHODS

In a retrospective study of 29 histologically proven RCCs in 29 patients (17 men, 12 women; mean age, 59 years), examinations were performed with a 16-MDCT scanner. The protocol included unenhanced and three-phase (arterial, portal, and nephrographic-excretory) contrast-enhanced CT. The data were analyzed by two reviewers blinded to the histopathologic results. Any discrepancy was resolved by consensus. The presence of a regular, high- or low-attenuation halo surrounding a renal neoplasm was considered to represent renal pseudocapsule. The accuracy of MDCT in the detection of pseudocapsule with the histopathologic results as the standard of reference was evaluated. Unenhanced transverse images and multiplanar reformations in the transverse, coronal, and sagittal planes of each contrast-enhanced phase were separately analyzed. The chi-square two-way test was used to compare each CT phase and multiplanar reformation with histologic results.

RESULTS

The mean diameter of RCCs on CT scans was 5.6 cm (range, 2.8-15 cm), in accordance with the pathologic result. MDCT enabled detection of renal pseudocapsule in 20 of 29 RCCs with 83% sensitivity, 80% specificity, 95% positive predictive value, 50% negative predictive value, and 83% overall accuracy. Imaging in the portal and nephrographic phases with coronal and sagittal reformations proved more accurate in the detection of pseudocapsule (p < 0.05).

CONCLUSION

Multiphase MDCT with multiplanar reformations had satisfactory results in the detection of renal pseudocapsule in RCC.

Renal cell carcinoma: attenuation values on unenhanced CT

OBJECTIVE

The purpose of this study is to analyze the attenuation values of pathologically proven renal cell carcinomas (RCCs) on unenhanced CT and to determine the range of values wherein malignancy should be considered.

MATERIALS AND METHODS

A retrospective review was performed of 189 consecutive patients with 193 pathologically proven RCCs 1 cm or larger on unenhanced CT. For each RCC, attenuation values were assessed throughout the tumor by continuous sampling with a 25-100-mm(2) region of interest (ROI), avoiding foci of calcification and peritumoral volume averaging. The lowest and highest ROI attenuation values per lesion were recorded. Each tumor was categorized as either homogeneous or heterogeneous on the basis of visual inspection with soft-tissue window settings.

RESULTS

The 193 malignant tumors ranged in size from 1.1 to 20.1 cm (mean [± SD], 5.1 ± 3.4 cm). Eighteen RCCs (9.3%) were homogeneous in appearance on unenhanced CT. The minimum and maximum ROI attenuation values obtained by sampling throughout each tumor were 27.5 ± 10.4 HU (range, 4-67 HU) and 39.7 ± 10.6 HU (range, 21-80 HU), respectively. Regional areas of minimum attenuation less than 20 HU and maximum attenuation greater than 70 HU were seen in 24.9% (48/193) and 2.1% (4/193) of RCCs, respectively. However, all 193 RCCs (100%) were predominantly composed of noncalcific regions within 20-70 HU; 72.5% (140/193) fell entirely within this 20-70 HU "danger zone," including all 18 homogeneous lesions.

CONCLUSION

All proven RCCs in this series contained substantial noncalcified regions that measured 20-70 HU in ROI attenuation on unenhanced CT. Indeterminate renal lesions on unenhanced CT measuring within this 20-70-HU danger zone warrant further workup, whereas lesions that fall entirely outside this range may be considered benign.

CT urography for hematuria

Hematuria can signify serious disease such as bladder cancer, upper urinary tract urothelial cell carcinoma (UUT-UCC), renal cell cancer or urinary tract stones. CT urography is a rapidly evolving technique made possible by recent advances in CT technology. CT urography is defined as CT examination of the kidneys, ureters and bladder with at least one series of images acquired during the excretory phase after intravenous contrast administration. The reasoning for using CT urography to investigate hematuria is based on its high diagnostic accuracy for urothelial cell carcinoma (UCC) and favorable comparison with other imaging techniques. The optimum diagnostic imaging strategy for patients with hematuria at high-risk for UCC involves the use of CT urography as a replacement for other imaging tests (ultrasonography, intravenous urography, or retrograde ureteropyelography) and as a triage test for cystoscopy, resulting in earlier diagnosis and improved prognosis of bladder cancer, UUT-UCC, renal cell cancer and stones. Current problems with CT urography for investigating hematuria might be solved with a formative educational program simulating clinical reporting to reduce reader error, and a new technique for image-guided biopsy of UUT-UCC detected by CT urography for histopathological confirmation of diagnosis and elimination of false-positive results. CT urography is recommended as the initial imaging test for hematuria in patients at high-risk for UCC.

Pretreatment imaging can be used to select imaging guidance, ultrasound alone versus CT plus ultrasound, for percutaneous renal radiofrequency ablation

OBJECTIVE

Although CT is most commonly used for guidance of radiofrequency ablation (RFA) of renal masses, other publications have shown that ultrasound alone may be used. Therefore, we compared the complications and technical effectiveness of renal RFA guided by ultrasound alone versus combined CT and ultrasound guidance.

MATERIALS AND METHODS

We retrospectively analyzed outcomes and complications of percutaneous renal RFA in two groups of patients for whom RFA was guided by either ultrasound alone (group 1) or combined CT and ultrasound (group 2). The sole factor in determining the method of guidance was preablation imaging. All other technical factors were consistent between the two groups.

RESULTS

There were 28 masses in 27 patients in group 1 and 32 masses in 29 patients in group 2. There was an overall major complication rate of 3.3% (2/60). Major complications occurred equally in group 2 (3.1% [1/32]) compared with group 1 (3.6% [1/28]). Overall ablative effectiveness was 93% (26/28) in group 1 and 84% (27/32) in group 2. There was no statistical difference between the two groups.

CONCLUSION

In proper hands, sonography guidance alone is a safe and effective method for performance of renal RFA in preselected cases and can decrease CT utilization. The use of CT is reserved for situations in which pretreatment RFA imaging suggests difficulty in ultrasound mass visualization or when the mass is in close proximity to structures that may be injured by thermal ablation.

Evaluation of diagnostic strategies for bladder cancer using computed tomography (CT) urography, flexible cystoscopy and voided urine cytology: results for 778 patients from a hospital haematuria clinic

Study Type - Diagnostic (exploratory cohort) Level of Evidence 2b What's known on the subject? and What does the study add? Haematuria clinics with same day imaging and flexible cystoscopy are an efficient way for investigating patients with haematuria. The principal role of haematuria clinics with reference to bladder cancer is to determine which patients are 'normal' and may be discharged, and which patients are abnormal and should undergo rigid cystoscopy. It is well recognised that CT urography offers a thorough evaluation of the upper urinary tract for stones, renal masses and urothelial neoplasms but the role of CT urography for diagnosing bladder cancer is less certain. The aim of the present study was to evaluate the diagnostic accuracy of CT urography in patients with visible haematuria aged >40 years and to determine if CT urography has a role for diagnosing bladder cancer. This study shows that the optimum diagnostic strategy for investigating patients with visible haematuria aged >40 years with infection excluded is a combined strategy using CT urography and flexible cystoscopy. Patients positive for bladder cancer on CT urography should be referred directly for rigid cystoscopy and so avoid flexible cystoscopy. The number of flexible cystoscopies required therefore may be reduced by 17%. The present study also shows that the diagnostic accuracy of voided urine cytology is too low to justify its continuing use in a haematuria clinic using CT urography and flexible cystoscopy.

OBJECTIVES

To evaluate and compare the diagnostic accuracy of computed tomography (CT) urography with flexible cystoscopy and voided urine cytology for diagnosing bladder cancer. To evaluate diagnostic strategies using CT urography as: (i) an additional test or (ii) a replacement test or (iii) a triage test for diagnosing bladder cancer in patients referred to a hospital haematuria rapid diagnosis clinic.

PATIENTS AND METHODS

The clinical cohort consisted of a consecutive series of 778 patients referred to a hospital haematuria rapid diagnosis clinic from 1 March 2004 to 17 December 2007. Criteria for referral were at least one episode of macroscopic haematuria, age >40 years and urinary tract infection excluded. Of the 778 patients, there were 747 with technically adequate CT urography and flexible cystoscopy examinations for analysis. On the same day, patients underwent examination by a clinical nurse specialist followed by voided urine cytology, CT urography and flexible cystoscopy. Voided urine cytology was scored using a 5-point system. CT urography was reported immediately by a uroradiologist and flexible cystoscopy performed by a urologist. Both examinations were scored using a 3-point system: 1, normal; 2, equivocal; and 3, positive for bladder cancer. The reference standard consisted of review of the hospital imaging and histopathology databases in December 2009 for all patients and reports from the medical notes for those referred for rigid cystoscopy. Follow-up was for 21-66 months.

RESULTS

The prevalence of bladder cancer in the clinical cohort was 20% (156/778). For the diagnostic strategy using CT urography as an additional test for diagnosing bladder cancer, when scores of 1 were classified as negative and scores of 2 and 3 as positive, sensitivity was 1.0 (95% confidence interval [CI] 0.98-1.00), specificity was 0.94 (95% CI 0.91-0.95), the positive predictive value (PPV) was 0.80 (95% CI 0.73-0.85) and the negative predictive value (NPV) was 1.0 (95% CI 0.99-1.00). For the diagnostic strategy using CT urography as a replacement test for flexible cystoscopy for diagnosing bladder cancer, when scores of 1 were classified as negative and scores of 2 and 3 as positive, sensitivity was 0.95 (95% CI 0.90-0.97), specificity was 0.83 (95% CI 0.80-0.86), the PPV was 0.58 (95% CI 0.52-0.64), and the NPV was 0.98 (95% CI 0.97-0.99). Similarly using flexible cystoscopy for diagnosing bladder cancer, if scores of 1 were classified as negative and scores of 2 and 3 as positive, sensitivity was 0.98 (95% CI 0.94- 0.99), specificity was 0.94 (95% CI 0.92-0.96), the PPV was 0.80 (95% CI 0.73-0.85) and the NPV was 0.99 (95% CI 0.99-1.0). For the diagnostic strategy using CT urography and flexible cystoscopy as a triage test for rigid cystoscopy and follow-up (option 1), patients with a positive CT urography score are referred directly for rigid cystoscopy, and patients with an equivocal or normal score were referred for flexible cystoscopy. Sensitivity was 1.0 (95% CI 0.98-1.0), specificity was 0.94 (95% CI 0.91-0.95), the PPV was 0.80 (95% CI 0.73-0.85), and the NPV was 1.0 (95% CI 0.99-1.0). For the diagnostic strategy using CT urography and flexible cystoscopy as a triage test for rigid cystoscopy and follow-up (option 2), patients with a positive CT urography score are referred directly for rigid cystoscopy, patients with an equivocal score are referred for flexible cystoscopy and patients with a normal score undergo clinical follow-up. Sensitivity was 0.95 (95% CI 0.90-0.97), specificity was 0.98 (95% CI 0.97-0.99), the PPV was 0.93 (95% CI 0.87-0.96), and the NPV was 0.99 (95% CI 0.97-0.99). For voided urine cytology, if scores of 0-3 were classified as negative and 4-5 as positive for bladder cancer, sensitivity was 0.38 (95% CI 0.31-0.45), specificity was 0.98 (95% CI 0.97-0.99), the PPV was 0.82 (95% CI 0.72-0.88) and the NPV was 0.84 (95% CI 0.81-0.87).

CONCLUSIONS

There is a clear advantage for the diagnostic strategy using CT urography and flexible cystoscopy as a triage test for rigid cystoscopy and follow-up (option 1), in which patients with a positive CT urography score for bladder cancer are directly referred for rigid cystoscopy, but all other patients undergo flexible cystoscopy. Diagnostic accuracy is the same as for the additional test strategy with the advantage of a 17% reduction of the number of flexible cystoscopies performed. The sensitivity of voided urine cytology is too low to justify its continuing use in a hospital haematuria rapid diagnosis clinic using CT urography and flexible cystoscopy.

Predictors of locally advanced and metastatic disease in patients with small renal masses

Study Type - Prognosis (case series) Level of Evidence 4 What's known on the subject? and What does the study add? There is a small cohort of patients who have small renal masses with metastatic potential, yet risk factors for having this more aggressive disease are largely unknown. In a large sampling of the US population, older patients and men were more likely to have small renal masses at an advanced stage.

OBJECTIVES

To assess the prevalence metastatic and locally advanced renal cell carcinoma (RCC) in the US population with small renal masses (SRMs). To determine what patient and tumour characteristics predict having more advanced SRMs.

PATIENTS AND METHODS

Using the Surveillance, Epidemiology and End Results (SEER) registry, we identified 14, 962 patients who were diagnosed between 1988 and 2007 with RCC ≤ 3 cm in size. Patients were separated by stage into those with metastatic, locally advanced and localized disease. Differences in baseline characteristics between patients in these three groups were assessed. After controlling for age, sex, grade, tumour size and year of surgery, a logistic regression analysis was performed to determine the likelihood of having non-localized disease.

RESULTS

In the SEER cohort, 13, 574 (90.7%) patients with RCC ≤ 3 cm in size were diagnosed with localized disease, 938 (6.3%) patients had invasion beyond the kidney into regional lymph nodes or nearby organs, and 450 (3.0%) patients had distant metastasis. Patients with metastasis were older (65.9 years) compared to those with localized disease (59.5 years) (P < 0.001). Independent preoperative predictors of having more aggressive disease at diagnosis (locally advanced/metastatic) included older age, particularly age >70 years (odds ratio, OR, 2.42; 95% confidence interval, CI, 2.03-2.88), male sex (OR, 1.50; 95% CI, 1.33-1.70) and tumour size >2.5 (OR, 1.41; 95% CI, 1.25-1.58).

CONCLUSIONS

A small subset (3%) of patients in the USA with RCC ≤ 3 cm in size have distant metastasis. Older patients, men and those with tumours 2.5-3.0 cm in size have a greater probability of presenting with non-localized disease . Clinicians should be aware that there is a risk of metastases in patients with SRMs and also familiarize themselves with the characteristics associated with advanced disease.

Renal artery embolization: application and success in patients with renal cell carcinoma and angiomyolipoma

Renal artery embolization is a procedure primarily performed by interventional radiologists that can be utilized for treatment of renal tumors, both malignant and benign. It has many applications, including pretreatment of renal cell carcinomas prior to planned resection to decrease hemorrhagic complications intraoperatively, treatment of malignant renal tumor in patients who are not deemed suitable surgical candidates, as well as treatment of benign renal tumors and their potential hemorrhagic complications. There are many different techniques. We describe how the procedure is approached at the University of Florida-Gainesville and provide examples of two cases, a renal cell carcinoma and an angiomyolipoma, treated at our institution with transcatheter embolotherapy.

Detection of renal lesion enhancement with dual-energy multidetector CT

PURPOSE

To determine whether dual-energy multidetector CT enables detection of renal lesion enhancement by using calculated nonenhanced images with spectral-based extraction in a non-body weight-restricted patient population.

MATERIALS AND METHODS

Between January 2008 and December 2009, 139 patients were enrolled in this prospective HIPAA-compliant, institutional review board-approved study. Written informed consent was obtained from all patients. After single-energy nonenhanced 120-kVp CT images were acquired, contrast material-enhanced dual-energy multidetector CT images were acquired at 80 and 140 kVp. Calculated nonenhanced images were generated by using spectral-based iodine extraction. Lesion attenuation was measured on the acquired nonenhanced, calculated nonenhanced, and 140-kVp contrast-enhanced nephrographic images. Enhancement, defined as a 15-HU or greater increase in attenuation on the nephrographic images, was assessed by using the baseline attenuation on the acquired and calculated nonenhanced images. Acquired nonenhanced versus calculated nonenhanced image attenuation, as well as enhancement values, were compared by using paired Student t tests and Bland-Altman plots.

RESULTS

Hypoattenuating (n = 66) and hyperattenuating (n = 28) cysts, angiomyolipomas (n = 18), and solid enhancing lesions (n = 27) were detected. Mean attenuation values for hypoattenuating cysts on the acquired and calculated nonenhanced CT images were 6.5 HU ± 5.8 (standard deviation) and 8.1 HU ± 3.1 (P = .13), respectively, with corresponding enhancement values of 1.1 HU ± 5.2 and -0.5 HU ± 6.2 (P = .12), respectively. Mean values for hyperattenuating cysts were 29.4 HU ± 5.6 on acquired images and 31.7 HU ± 5.1 on calculated images (P = .39) (corresponding enhancement, 4.7 HU ± 3.3 and 2.3 HU ± 4.1, respectively; P = .09). Mean values for fat-containing enhancing lesions were -90.6 HU ± 24.7 on acquired images and -85.9 HU ± 23.7 on calculated images (P = .57) (corresponding enhancement, 18.2 HU ± 10.1 and 13.6 HU ± 10.7, respectively; P = .19). Mean attenuation values for solid enhancing lesions were 26.0 HU ± 15.0 on acquired images and 27.7 HU ± 14.9 on calculated images (P = .45) (corresponding enhancement, 60.3 HU ± 13.1 and 58.3 HU ± 15.5, respectively; P = .38).

CONCLUSION

Dual-energy CT acquisitions with spectral-based postprocessing enabled accurate detection of renal lesion enhancement across the attenuation spectrum of frequently encountered renal lesions in a non-body habitus-restricted patient population.

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.

Contrast enhanced ultrasound of renal masses

Contrast enhanced ultrasound (CEUS) has gained clinical importance over the last years for the characterization of hepatic masses. Its role in extrahepatic indications has been investigated repeatedly but has been less comprehensively studied. Currently more than 50% of renal masses are incidentally diagnosed, mostly by B-mode ultrasound. The method of choice for characterization of renal lesions is contrast enhanced computed tomography (CECT). In the case of cystic lesions CECT refers to the Bosniak classification for cystic lesions to assess the risk of malignant behavior. The majority of masses are renal cell carcinoma, but the exact proportion is controversial. Disadvantages of CECT are a significant risk for patients with impaired renal function, allergic reactions and hyperthyroidism due to iodinated contrast agents. Several studies concerning CEUS for the characterization of both solid and cystic renal lesions have been published, but prospective multicenter studies are missing, the presented data being mainly descriptive. The aim of the this manuscript is to review the current literature for CEUS in renal masses, to summarize the available data and focus on possible concepts for studies in the future.

The characterization of small hypoattenuating renal masses on contrast-enhanced CT

PURPOSE

To determine if small hypoattenuating renal masses can be characterized as simple cysts or renal cell carcinomas on contrast-enhanced computed tomography (CT).

MATERIALS AND METHODS

We retrospectively identified 20 small (<or=1.5 cm) hypoattenuating renal masses seen on contrast enhanced CT, consisting of 14 simple cysts and six renal cell carcinomas. Three independent readers recorded subjective visual impression (five-point scale from 1=definitely fluid to 5=definitely solid), CT attenuation, border (well circumscribed or ill defined), and shape (ovoid or irregular) for each lesion.

RESULTS

The overall area under the receiver operator characteristic curves for subjective visual impression, CT attenuation, border, and shape were 0.97, 0.82, 0.59, and 0.55, respectively. Using dichotomized ratings (1-2=cyst and 3-5=carcinoma), subjective impression had a sensitivity and specificity of 100% and 79-100%, respectively, for the diagnosis of renal cell carcinoma. Using a threshold of 50 Hounsfield Units (HU) or more, CT attenuation had a sensitivity and specificity of 100% and 43-64%, respectively.

CONCLUSION

Small hypoattenuating renal masses can be characterized with reasonable accuracy by subjective impression and CT attenuation; lesions that appear solid on visual inspection or have an attenuation value of 50 HU or more are likely to be renal cell carcinoma.

Radiologic evaluation of small renal masses (I): pretreatment management

When characterizing a small renal mass (SRM), the main question to be answered is whether the mass represents a surgical or nonsurgical lesion or, in some cases, if followup studies are a reasonable option. Is this a task for a urologist or a radiologist? It is obvious that in the increasing clinical scenario where this decision has to be made, both specialists ought to work together. This paper will focus on the principles, indications, and limitations of ultrasound, CT, and MRI to characterize an SRM in 2008 with a detailed review of relevant literature. Special emphasis has been placed on aspects regarding the bidirectional information between radiologists and urologists needed to achieve the best radiological approach to an SRM.

Current use of computed tomographic urography: survey of the society of uroradiology

OBJECTIVE

To determine uroradiologists' opinions and practices regarding computed tomographic (CT) urography.

METHODS

A Web-based survey was sent via e-mail to all 259 members of the Society of Uroradiology. Of the 229 successfully delivered e-mails, 90 (39%) members responded.

RESULTS

Of 90 uroradiologists, 87% perform CT urography. Compared with intravenous (IV) urography, 69% of uroradiologists use CT urography more than 75% of the time urinary tract imaging is requested; 27% stated that CT urography has completely replaced IV urography. Most uroradiologists perform CT urography using multidetector-row CT alone (79%) and use a 3-phase technique (52%) using a single injection (76%) of contrast material at 3 mL/s (52%) without a compression device (81%) and with the patient in supine position (80%).

CONCLUSIONS

Most uroradiologists use CT urography in their practice today; some no longer perform IV urography. Variability in multidetector-row CT technique suggests that more research is needed to determine the optimal protocol.

Histological characterisation of small renal masses and incidence of silent renal masses

With the introduction of sonographic and CT examinations, the number of small renal masses detected has increased. Benign neoplastic lesions are usually smaller than 4 cm in size, whilst the most common types of renal cell carcinomas have a mean size greater than that, but we must not forget that a significant number of small masses are renal cell carcinomas; even though the rate of benign cases increases as the diameter of the lesions decreases, therefore, size itself cannot be used to rule out a diagnostic of malignancy and often image characteristics are not enough to predict the nature of the lesion with certainty. In this case, histological confirmation must be recommended. Ideally, the histological study must be conducted on the surgical specimen, even though biopsy can be an option in selected cases.

Bladder cancer detection with CT urography in an Academic Medical Center

PURPOSE

To evaluate the performance characteristics of computed tomographic (CT) urography for the detection of bladder cancer in patients at risk for the disease.

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective HIPAA-compliant review of medical records of 2600 consecutive patients undergoing CT urography. Of these, 838 CT urograms in 779 patients (449 men, mean age of 62 years, range of 27-92 years; 330 women, mean age of 56 years, range of 18-86 years) evaluated for hematuria or a history of urothelial cancer, who had undergone cystoscopy within 6 months of the CT urogram, were included in the study. Clinical reports of CT urograms containing a bladder lesion interpreted as suspicious for malignancy were classified as positive. All others were classified as negative. Cystoscopy reports were classified as positive if a lesion underwent biopsy or was resected or negative if no lesion was detected. Performance characteristics for both CT urography and cystoscopy were determined by using pathologic findings or clinical follow-up as the reference standard. Ninety-five percent confidence intervals were estimated for each test characteristic.

RESULTS

The overall sensitivity, specificity, accuracy, positive predictive value, and negative predictive value (NPV) for bladder cancer detection were 79% (117 of 149), 94% (649 of 689), 91% (766 of 838), 75% (117 of 157), and 95% (649 of 681) for CT urography and 95% (142 of 149), 92% (634 of 689), 93% (776 of 838), 72% (142 of 197), and 99% (634 of 641) for cystoscopy. The NPV of CT urography was higher in patients evaluated for hematuria alone (98%, 589 of 603). However, the accuracy of CT urography was considerably lower in patients with a prior urothelial malignancy (78%, 123 of 158).

CONCLUSION

CT urography is an accurate noninvasive test for detecting bladder cancer in patients at risk for the disease. The high NPV of CT urography in patients with hematuria may obviate cystoscopy in selected patients.

Imaging of hematuria

Hematuria may have a number of causes, of which the more common are urinary tract calculi, urinary tract infection, urinary tract neoplasms (including renal cell carcinoma and urothelial tumors), trauma to the urinary tract, and renal parenchymal disease. This article discusses the current status of imaging of patients suspected of having urologic causes of hematuria. The role of all modalities, including plain radiography, intravenous urography or excretory urography, retrograde pyelography, ultrasonography, and multidetector computed tomography (MDCT) in evaluation of these patients is discussed. The article highlights the current status of MDCT urography in imaging of patients with hematuria, and discusses various-often controversial-issues, such as optimal protocol design, accuracy of the technique in imaging of the urothelium, and the significant issue of radiation dose associated with MDCT urography.

Multi-detector row CT of the kidney: Optimizing scan delays for bolus tracking techniques of arterial, corticomedullary, and nephrographic phases

PURPOSE

To determine optimal scan delays for renal arterial-, corticomedullary-, and nephrographic-phase imaging with multi-detector row computed tomography (MDCT) of the kidney using a bolus-tracking technique.

METHODS AND MATERIALS

One hundred and twenty-eight patients underwent three-phase CT scan of the kidney with eight-row MDCT after receiving 2 mL/kg of 300 mgI/mL contrast medium at 4 mL/s. Patients were prospectively randomized into three groups with different scan delays for the three scan phases (arterial, corticomedullary, and nephrographic) after bolus-tracking triggered at 50 HU of aortic contrast enhancement: group 1 (5, 20, 45 s); group 2 (10, 25, 50s); and group 3 (15, 30, 55 s). Mean CT values (HU) of the abdominal aorta, renal artery, renal vein, renal cortex, and renal medulla were measured; increases in CT values pre- to post-contrast were assessed as contrast enhancement. Renal artery-to-vein and renal cortex-to-medulla contrast differences were also assessed. Qualitative analysis was also performed.

RESULTS

Mean renal artery enhancement was 240-288 HU at 5-15s after the trigger and peaked at 10s (P<.001). Mean renal cortical enhancement was 195-217 HU at 10-30s and peaked at 25s (P<.01). Contrast enhancement in the renal medulla increased gradually and reached mean 145 HU at 55 s. Cortex-to-medulla contrast difference was high (110-140 HU) at 5-30s and decreased below 30 HU at 45 s after the trigger. Renal artery-to-vein contrast difference was high (121-125 HU) at 5-10s. Qualitative results correlated well with quantitative results.

CONCLUSION

For the injection protocol used in this study, optimal scan delays after the bolus-tracking trigger were 5-10 s for renal arterial, 15-25 s for corticomedullary, and 50-55 s for nephrographic phases.

Hyperattenuating renal masses: etiologies, pathogenesis, and imaging evaluation

Some renal masses have higher attenuation than the surrounding renal parenchyma at computed tomography (CT). Their hyperattenuation is usually the result of proteinaceous fluid or densely packed cells. Most hyperattenuating renal masses are benign hemorrhagic or proteinaceous cysts. However, solid enhancing hyperattenuating renal masses may have malignant as well as benign causes. Possible malignant causes include renal cell carcinoma and lymphoma; benign causes include angiomyolipoma with minimal fat. It is important to identify the cause of a hyperattenuating renal mass so as to avoid unnecessary surgical resection or ablation. CT may be useful for diagnosing benign hyperattenuating renal cysts, hematomas, and vascular anomalies that appear masslike. However, some solid, enhancing, hyperattenuating masses cannot be diagnosed confidently with CT alone: Small (< or = 3-cm-diameter), homogeneously enhancing, hyperattenuating renal masses depicted on CT images may be either benign angiomyolipomas with minimal fat or renal cell carcinomas. Magnetic resonance (MR) imaging may be helpful for differentiating between angiomyolipomas with minimal fat and clear cell renal cell carcinomas; however, differentiation between angiomyolipomas with minimal fat and papillary renal cell carcinomas often is not possible on the basis of MR imaging. In such cases, a percutaneous biopsy may be useful for diagnosis. If the results of MR imaging and percutaneous biopsy are not definitive, surgery is warranted.

Management of renal tumors by image-guided radiofrequency ablation: experience in 105 tumors

Aims

In this article we present our experience with radiofrequency ablation (RFA) in the treatment of 105 renal tumors.

Materials and Methods

RFA was performed on 105 renal tumors in 97 patients, with a mean tumor size of 32 mm (11–68 mm). The mean patient age was 71.7 years (range, 36–89 years). The ablations were carried out under ultrasound (n = 43) or CT (n = 62) guidance. Imaging follow-up was by contrast-enhanced CT within 10 days and then at 6-monthly intervals. Multivariate analysis was performed to determine variables associated with procedural outcome.

Results

Eighty-three tumors were completely treated at a single sitting (79%). Twelve of the remaining tumors were successfully re-treated and a clinical decision was made not to re-treat seven patients. A patient with a small residual crescent of tumor is under follow-up and may require further treatment. In another patient, re-treatment was abandoned due to complicating pneumothorax and difficult access. One patient is awaiting further re-treatment. The overall technical success rate was 90.5%. Multivariate analysis revealed tumor size to be the only significant variable affecting procedural outcome. (p = 0.007, Pearson χ²) Five patients had complications. There have been no local recurrences.

Conclusion

Our experience to date suggests that RFA is a safe and effective, minimally invasive treatment for small renal tumors.

Imaging in genitourinary cancer from the urologists' perspective

It is well established that advances in imaging may lead to early cancer detection, more accurate tumour staging and consequently adequate treatment, better monitoring of the disease and enhanced surveillance for recurrences after treatment. This manuscript reviews the current use of imaging in genitourinary cancer and explores the impact of imaging findings in clinical management. Additionally, an effort has been made to present the emerging imaging modalities and also their possible role in diagnosis and treatment of these cancers.

Computed tomography urography technique, indications and limitations

PURPOSE OF REVIEW

The review discusses the different techniques of computed tomography urography reported in the literature and presents the author's preferred approach.

RECENT FINDINGS

Multiphase computed tomography urography offers a comprehensive evaluation of the urinary tract but at the cost of a large dose of contrast medium (100-150 ml), high radiation dose and massive number of images for interpretation. Diuresis induced by frusemide (10 mg) is reported to improve the depiction of ureters in the excretory phase of the examination. The author's preferred approach is a limited computed tomography urography which includes precontrast scanning of the kidneys, followed by an excretory phase 5 min after intravenous injection of 50 ml of contrast medium and 10 mg of frusemide. This limited examination in the author's experience provides a satisfactory evaluation of the urinary tract in the majority of patients, without inflicting a high radiation dose on the patient.

SUMMARY

A limited computed tomography urography examination is adequate for the majority of patients requiring excretory urography and a superior replacement of conventional intravenous urography. Information provided by a multiphase computed tomography urography examination is beneficial only in a small number of patients.

Imaging of kidney cancer

Advances in molecular genetics have expanded the understanding of renal cell tumors. Now it is understood that renal cortical tumors are a family of neoplasms with distinct cytogenetics and molecular defects, unique histopathologic features, and different malignant potentials. Imaging contributes to clinical management of patients with renal tumors in providing diagnostic information for tumor detection, characterization, staging, treatment planning, and follow-up.

Renal Mass Core Biopsy: Accuracy and Impact on Clinical Management

OBJECTIVE

The objective of our study was to determine the accuracy of imaging-guided percutaneous renal mass biopsy and its impact on clinical management.

MATERIALS AND METHODS

With institutional review board approval, we retrospectively reviewed imaging-guided renal biopsies performed by radiologists at our institution between February 1999 and July 2005. Patient records, pathology reports, and imaging studies were reviewed. Concordance of biopsy diagnosis and follow-up data was assessed. Significant impact on clinical management was determined in collaboration with two experienced urologists and was defined as a change from no therapy to therapy, including surgery, tumor ablation, chemotherapy, or radiation.

RESULTS

Two hundred seventy-six renal biopsies were performed during the study period. Of these, 123 were random biopsies and fine-needle technique was used for one; these 124 were excluded. One hundred fifty-two renal mass biopsies were performed using coaxial 18-gauge core needle technique in 125 patients (55 women, 70 men; average age, 60 years; range, 28-90 years). There were two (1.3%) postprocedural hematomas (one [0.7%] requiring blood transfusion) and one (0.7%) delayed renal pseudoaneurysm attributed to biopsy. No tumor seeding was identified. In 85 biopsies (56%), malignant neoplasm was found, 61 biopsies (40%) yielded benign findings, and six (4%) were nondiagnostic. The sensitivity for malignancy was 97.7%; specificity, 100%; positive predictive value, 100%; and negative predictive value, 100%. At least 92 (60.5%) biopsy results significantly impacted clinical management.

CONCLUSION

Imaging-guided percutaneous core needle biopsy of renal masses is safe and highly accurate. Tissue diagnosis alters clinical decision making in a majority of the cases and may allow a number of unnecessary nephrectomies to be avoided.

Multi-detector row CT urography of normal urinary collecting system: furosemide versus saline as adjunct to contrast medium

PURPOSE

To retrospectively evaluate whether intravenous furosemide, either alone or in addition to intravenous saline, improved depiction of the normal urinary collecting system at multi-detector row computed tomographic (CT) urography.

MATERIALS AND METHODS

Institutional review board approval for review of patient images and medical records was obtained; informed consent was not required for this HIPAA-compliant study. Excretory phase images from multi-detector row CT urography in 87 patients (44 women, 43 men; age range, 21-83 years; mean, 53 years) were reviewed. Examinations were performed with, in addition to intravenous contrast medium, 250 mL of intravenous normal saline alone (n = 35), both 250 mL of normal saline and 10 mg of intravenous furosemide (n = 26), or 10 mg of furosemide alone (n = 26). Three readers, blinded to the imaging technique used, individually assigned opacification scores to each of six urinary collecting system segments. Urinary distention was assessed by one reader by measuring transverse widths of the proximal, middle, and distal ureteral segments. Mean opacification scores for each segment and mean ureteral width measurements for each technique were compared by using the Student t test.

RESULTS

Mean opacification scores achieved with furosemide were significantly higher than those achieved with saline for the middle (P </= .008) and distal (P < .001) ureteral segments. Similarly, mean ureteral widths were significantly higher with furosemide than with saline for the middle (P </= .04) and distal segments (P = .01). There was no overall benefit of administering both saline and furosemide.

CONCLUSION

To optimize opacification and distention of the normal urinary collecting system, contrast material-enhanced multi-detector row CT urography may be supplemented with intravenous furosemide alone.

Maximizing clinical information obtained by CT

CT scanning is an integral part of the urologist's practice today. It is the most commonly used imaging modality and the one with which urologists are most familiar. CT urography, CT angiography, and 3D reconstruction enable the urologist to perform comprehensive evaluations of patients who have different urologic diseases, using a single imaging modality. It is thus prudent that urologists become familiar with CT applications, to maximize the clinical information available from them.