Radiologic evaluation of small and indeterminant renal masses

Percutaneous Cryoablation vs Partial Nephrectomy: Cost Comparison of T1a Tumors

PURPOSE

To compare cost of percutaneous cryoablation vs open and robot-assisted partial nephrectomy of T1a renal masses from the hospital perspective.

MATERIALS AND METHODS

We retrospectively compared cost, clinical and tumor data of 37 percutaneous cryoablations to 26 open and 102 robot-assisted partial nephrectomies. Total cost was the sum of direct and indirect cost of procedural and periprocedural variables. Clinical data included demographics, Charlson Comorbidity Index (CCI), hospitalization time, complication rate, ICU admission rate, and 30-day readmission rates. Tumor data included size, RENAL nephrometry score, and malignancy rate. Student's t-test was used for continuous variables and Fisher's exact or chi-square tests for categorical data.

RESULTS

Mean total cost was lower for percutaneous cryoablation than open or robot-assisted partial nephrectomy: $6067 vs $11392 or $11830 (p<0.0001) with lower cost of procedure room: $1516 vs $3272 or $3254 (p<0.0001), room and board: $95 vs $1907 or $1106 (p<0.0001), anesthesia: $684 vs $1223 or $1468 (p<0.0001), and laboratory/pathology fees: $205 vs $804 or $720 (p<0.0001). Supply and device cost was higher than open: $2596 vs $1352 (p<0.0001), but lower than robot-assisted partial nephrectomy: $3207 (p=0.002). Mean hospitalization times were lower for percutaneous cryoablation (p<0.0001), while age and CCI were higher (p<0.0001). No differences in tumor size, nephrometry score, malignancy rate complication, ICU, or 30-day readmission rates were observed.

CONCLUSION

Percutaneous cryoablation can be performed at significantly lower cost than open and robotic partial nephrectomies for similar masses.

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.

Optical property measurements establish the feasibility of photodynamic therapy as a minimally invasive intervention for tumors of the kidney

We measured the optical properties of freshly excised kidneys with renal parenchymal tumors to assess the feasibility of photodynamic therapy (PDT) in these patients. Kidneys were collected from 16 patients during surgical nephrectomies. Spatially resolved, white light, steady-state diffuse reflectance measurements were performed on normal and neoplastic tissue identified by a pathologist. Reflectance data were fit using a radiative transport model to obtain absorption (μa) and transport scattering coefficients (μs'), which define a characteristic light propagation distance, δ. Monte Carlo (MC) simulations of light propagation from cylindrical diffusing fibers were run using the optical properties extracted from each of the kidneys. Interpretable spectra were obtained from 14 kidneys. Optical properties of human renal cancers exhibit significant inter-lesion heterogeneity. For all diagnoses, however, there is a trend toward increased light penetration at longer wavelengths. For renal cell carcinomas (RCC), mean values of δ increase from 1.28 to 2.78 mm as the PDT treatment wavelength is increased from 630 to 780 nm. MC simulations of light propagation from interstitial optical fibers show that fluence distribution in tumors is significantly improved at 780 versus 630 nm. Our results support the feasibility of PDT in selected renal cancer patients, especially with photosensitizers activated at longer wavelengths.

Increased prevalence of simple renal cysts in patients with gout

The aim of this study was to determine the prevalence of simple renal cysts in gout patients and evaluate associated risk factors for its development. Hundred and forty-six patients followed at our outpatient Gout Unit and 47 sex- and age-matched healthy kidney donors who had undergone routine renal ultrasonography, using a static gray scale and real-time B-mode units with a 3.5- or 5.0-MHz transducer, were evaluated for the presence of renal cysts. Demographic and clinical characteristics of gout patients were evaluated considering possible risk factors for the occurrence of simple renal cysts such as age, male gender, hypertension, and renal impairment. The prevalence of simple renal cyst was 26.0 % in gout patients and 10.6 % in control group (P = 0.045). Gout patients with simple renal cysts presented less renal lithiasis than those without this complication (5.2 vs 25.9 %; P = 0.003) in spite of an overall higher frequency of renal stones in gout patients compared to control group (20.5 vs. 6.3 %, P = 0.025). The presence of simple renal cyst in gout was not associated with previously reported factors such as age (P = 0.296), male predominance (P = 0.688), hypertension (P = 0.314), and renal impairment (P = 254). Moreover, no association with disease duration (P = 0.843) or tophi (P = 0.616) was observed. In conclusion, gout patients have an increased prevalence of simple renal cysts associated with a lower occurrence of nephrolithiasis. Whether renal cysts have any protective effect in the development of nephrolithiasis in gout remains to be determined.

Progression to metastatic disease from a small renal cell carcinoma prospectively followed with an active surveillance protocol

With the widespread use of abdominal imaging to evaluate other medical conditions, many renal tumours are being diagnosed at earlier stages. Older patients have experienced the most significant increase in the incidence of renal cell carcinoma (RCC). This age group frequently has significant medical comorbidities. This has led to the concept of active surveillance for select patients with renal lesions that may not affect their mortality. However, the ultimate risk of active surveillance is the potential for developing metastases. This case report presents the development of metastatic disease from a small, incidentally detected and prospectively followed RCC with asymptomatic progression.

[Current treatment of small renal masses]

Incidental diagnosis of renal carcinoma (RC) is increasingly common due to widespread use of radiodiagnostic techniques for other conditions. In developed countries, incidental tumor account for more than 40% of detected tumors, and 80% of solid kidney tumors less than 4 cm in size are malignant. Standard treatment for these tumors is partial nephrectomy, and their relapse rate is 1%-2% The higher increase in diagnosis of this disease has occurred in patients aged 70 to 90 years, a group where associated comorbidities are very common. In the past two decades, in parallel to development of radiographic techniques, two ablation procedures achieving tumor necrosis through cold, cryotherapy, and through heat, radiofrequency, have become established. These procedures achieve 95% short- and long-term remissions in tumors less than 4 cm in size. In addition, since these procedures may be performed percutaneously, both complications and hospital stay have decreased. As early as in 1995, Bosniak, based on observation of the growth and behavior of small RCs for longer than 8 years, advocated a watchful waiting or active surveillance attitude. This article reports cryotherapy, our radiofrequency series, and a literature review.

CONCLUSIONS

In the event of elderly patients, concomitant diseases advising against surgery, multiple renal tumors, a solitary kidney, or patients who reject surgery, ablation procedures may be safe and effective when performed by expert hands, achieving mid-term oncological results similar to partial nephrectomy. Active surveillance has also been shown to be safe in the mid-term in adequately informed patients. To improve indications, new diagnostic procedures that help us differentiate the potentially more aggressive tumors will be required. Larger series and longer follow-ups are neede to confirm current results.

Comparison of CT-guided sclerotherapy with using 95% ethanol and 20% hypertonic saline for managing simple renal cyst

OBJECTIVE

We wanted to compare the efficacies of 95% ethanol and 20% hypertonic saline (HS) sclerotherapies that were performed in a single session under CT guidance for the management of simple renal cysts.

MATERIALS AND METHODS

A prospective series of 74 consecutive patients (average age: 57.6 +/- 8.1 years) with simple renal cysts were enrolled in this study. They were randomized into two groups and 95% ethanol or 20% HS, respectively, corresponding to 25% of the aspiration volume, was injected. Treatment success was determined six months later with follow-up clinical evaluation and performing ultrasonography.

RESULTS

The sclerotherapy was accepted as technically successful without major complications in all except two patients who were excluded because of a communication between the simple renal cyst and the pelvicalyceal collecting system. Thirty-six patients in the ethanol group received sclerotherapy with 95% ethanol and 36 patients in the HS group underwent sclerotherapy with 20% HS. The complete regression ratio of the ethanol group was significantly higher (94% versus 72%, respectively) than that of the HS group. There was one patient with partial regression in each group. The failure ratio of the ethanol group was significantly lower (3% versus 25%, respectively) than that of the HS group.

CONCLUSION

Ethanol sclerotherapy under CT guidance is a successful and safe procedure and it can be used for the treatment of simple renal cysts. Sclerotherapy with 95% ethanol is more effective than 20% HS sclerotherapy. Sclerotherapy with HS may be an option for patients preferring to undergo a less painful treatment procedure.

[Solid renal mass up to 4 cm. Analysis of the diagnostic procedures, TNM staging and surgical treatment]

OBJECTIVES

We perform a retrospective review of renal tumors operated with a maximum size of 4 cm to determine if the diagnostic methodology was adequate, the TMN staging prognostic accuracy (UICC 2002) and the goal surgical treatment.

MATERIAL AND METHOD

Between 1984 to 2005, 78 renal units form 74 patients (4 bilateral synchronous) operated at the Service of Urology of the Hospital Alemán de Buenos Aires. Age distribution, sex, presentation form (incidental and symptomatic), diagnostic methodology, laboratory variables, surgical treatment (partial or radical surgery), histopathology, Fuhrman grade, tumor size, bilaterality, multicentricity, TNM staging, evolution and survival (Kaplan Meier) were analyzed.

RESULTS

78 renal units from a total of 192, 40.62% were analyzed. The median age was 58.72 years. 69% were male and 31% female. The presentation form was 91.90 % incidental and symptomatic 8.10% (Hematuria in 5 and lung metastasis in 1). The diagnosis was performing with ultrasound and CT scan 63 cases, in 4 was also used resonance magnetic imaging (RMI) and in 7 ultrasound and RMI. Arteriography was used in 11 cases, 3 showed tumor and 8 were normal. Biopsy was performing in 5 cases, all positive for clear cells carcinoma. Globular sedimentation was the only one laboratory abnormality in 12 cases. Surgical treatment was radical surgery in 35 renal units (44.87%) and conservative surgery in 43 units (55.13%). Pathology clear cells carcinoma (CCC) 79.48%, papillary carcinoma 1.28%, angiomyolipoma (AML) 8.97%, oncocytoma 7.69% and adenoma 2.56%. The Fuhrman grade was 1 in 76.19%; 2 in 20.63% and 3 in 3.18%. Bilateral tumor were found in 4 cases 2 CCC, 1 CCC and AML and 1 CCC and adenoma. Tumor median size was 2.93 cm. Staging was T1a 96.82%, T3a 1.59% and T3aM+ 1.59%. Follow-up could be made in 54 of 61 cases. At median follow-up of 52.25 months, 50 cases were disease free, 3 died by progression at 18, 33 and 82 months and all of them were symptomatic tumors, 1 died by a non related cause. Survival rate was 94%.

CONCLUSIONS

1)Ultrasound and CT scan obtained a highest diagnostic accuracy for solid renal mass. Biopsy in selective cases could contribute to achieve a correct treatment strategy. 2) Conservative surgery was the goal treatment in selected tumors up to 4 cm. and we believe that TNM staging should contemplate the presentation form to improve the prognostic value.

Distinction of renal cell carcinomas from high-attenuation renal cysts at portal venous phase contrast-enhanced CT

PURPOSE

To determine if renal cell carcinomas can be distinguished from high-attenuation renal cysts on portal venous phase contrast material-enhanced computed tomographic (CT) scans.

MATERIALS AND METHODS

Fifty-seven renal cell carcinomas and 37 high-attenuation (>20 HU) renal cysts that were at least 1 cm in diameter were retrospectively identified in 90 patients who underwent portal venous phase contrast-enhanced CT. Two independent readers recorded the CT number and degree of internal heterogeneity (uniform or mildly, moderately, or markedly heterogeneous) of all lesions. Logistic regression analysis with adjustment for the two readers was used to examine the association between clinical and CT parameters and the final diagnosis. Stepwise logistic regression analysis was used to identify independent distinguishing variables, which were then incorporated in a classification and regression tree analysis to construct the most efficient classification algorithm.

RESULTS

Renal cell carcinomas were of significantly greater size (5.10 cm vs 2.84 cm, P <.001), mean attenuation (101.2 HU vs 55.3 HU, P <.001), and internal heterogeneity (P <.001) than high-attenuation renal cysts. Stepwise logistic regression showed attenuation and internal heterogeneity were both independent variables associated with final diagnosis, but lesion size was not an independent distinguishing variable after adjustment for internal heterogeneity. Classification and regression tree analysis demonstrated that an attenuation greater than 70 HU or the presence of moderate or marked internal heterogeneity was an accurate sign of renal cell carcinoma, with a sensitivity of 91% (52 of 57) for both readers and a specificity of 92% (34 of 37) for reader 1 and 84% (31 of 37) for reader 2.

CONCLUSION

On portal venous phase contrast-enhanced CT scans, attenuation greater than 70 HU or moderate or marked internal heterogeneity favor a diagnosis of renal cell carcinoma over a diagnosis of high-attenuation renal cyst.

Imaging for renal tumors

PURPOSE OF REVIEW

The present review summarizes current developments in the imaging of renal tumors.

RECENT FINDINGS

Computed tomography (CT), magnetic resonance imaging, and ultrasound are used for diagnosing, characterizing, and staging renal tumors. Recent advances have been made in many areas, but the most significant changes have occurred in helical CT. The traditional roles for CT and magnetic resonance imaging have been expanded to include the use of three-dimensional CT and magnetic resonance imaging as surgical planning tools. Three-phase CT scans are commonly performed for detection, characterization, and staging of renal lesions, but pelvic CT is probably not needed for preoperative staging. Three-phase CT scans are more sensitive for characterization and for identifying the renal vasculature. Enhancement characteristics on these scans can help to distinguish between different tumor types. Finally, CT urography is a promising alternative to conventional excretory urography, with the potential to simplify the imaging evaluation of patients with hematuria.

SUMMARY

Although ultrasound and magnetic resonance imaging have many indications for imaging renal tumors, CT, with new uses and improved diagnostic capabilities, remains the gold standard in renal imaging.

Renal imaging in patients requiring renal replacement therapy

Recent advances in imaging technology and interventional radiologic procedures have resulted in an increased variety of radiological techniques that can be used to assess patients who present with renal failure and require renal replacement therapy. This chapter provides an overview of the relative strengths and weaknesses of the available imaging methods. In particular, it covers the expanding role of the cross-sectional, noninvasive, multiplanar imaging techniques such as gray-scale and Doppler ultrasound, magnetic resonance imaging (MRI) and angiography (MRA), and nonenhanced helical or multislice computed tomography (CT). These imaging methods are increasingly replacing those used in the past, such as the conventional radiographic urogram, which requires a high dose of intravenous contrast media, and digital subtraction arteriography. The chapter also covers the radiologic investigation of complications of acquired renal cystic disease, including renal cell carcinoma, hemorrhage, cyst infection and rupture, and nephrolithiasis.

Enhancement characteristics of papillary renal neoplasms revealed on triphasic helical CT of the kidneys

OBJECTIVE

The purpose of this study was to determine whether renal tumor enhancement or heterogeneity on triphasic helical CT scans is predictive of the papillary cell subtype or nuclear grade of renal cell carcinoma.

MATERIALS AND METHODS

We reviewed the CT scans of 90 consecutive patients with renal masses who had undergone triphasic renal helical CT before a complete or partial nephrectomy (12 with papillary renal cell carcinomas, 66 with nonpapillary renal cell carcinomas, and 12 with benign lesions). Three radiologists who were unaware of the patients' diagnoses retrospectively and independently measured the attenuation of each patient's tumor, abdominal aorta, and normal renal parenchyma on the scans obtained during all three phases. Ratios of tumor-to-aorta enhancement and tumor-to-normal renal parenchyma enhancement were calculated for both of the phases performed after contrast material had been administered. Tumor heterogeneity was calculated as the difference between the highest and lowest attenuation values divided by the value of the enhancement of the aorta. Values were correlated with cell type and nuclear grade found at surgical pathology.

RESULTS

Low tumor-to-aorta enhancement and low tumor-to-normal renal parenchyma enhancement ratios on the vascular phase scans significantly correlated (p < 0.001) with papillary renal cell type carcinoma. Homogeneity and tumor-to-parenchyma enhancement ratios on the parenchymal phase scans also significantly correlated (p < 0.001) with papillary renal cell type carcinoma. Heterogeneity and tumor enhancement ratios did not correlate with the nuclear grade of the carcinoma.

CONCLUSION

Papillary renal cell carcinomas are typically hypovascular and homogeneous. A high tumor-to-parenchyma enhancement ratio (> or = 25%) essentially excludes the possibility of a tumor being papillary renal cell carcinoma. A low tumor-to-aorta enhancement ratio or tumor-to-normal renal parenchyma enhancement ratio is more likely to indicate papillary renal cell carcinoma.