Characterization Of Renal Masses Research Articles

Epidemiology and diagnostic assessment of small renal masses

The incidence of small renal masses has been rising over the last few decades. At the same time, mortality of renal cell carcinoma (RCC) is decreasing. These trends can be explained by the availability of improved therapeutic measures and the good prognosis of small renal masses (SRM) turning out to be histopathologically benign or of low malignancy in many cases. The aim of this article is to present epidemiology and diagnostic assessment of SRM. Statistics, basic research, guidelines. The incidence of SRM is rising due to the widespread use of imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and contrast-enhanced ultrasound (CEUS). Sensitivity is excellent for CEUS and for CECT in the characterization of SRM, while good specificity values can be reached by MRI. For characterization of complex cystic renal masses, CEUS has good diagnostic accuracy. Due to improved diagnostic possibilities, SRMs can be diagnosed in early asymptomatic stages. As SRM have agood prognosis and often are of low malignancy therapy, options should be carefully considered; especially in older patients, active surveillance should considered.

Role of MR Apparent Diffusion Coefficient in Characterization of Cystic Renal Masses Using 3T MRI

Now it is more than 30 years since we are using the Bosniak classification for cystic renal masses, which represents the scale for cancer probability using imaging features. First, we used ultrasound, then CT then MRI for characterization. Many studies were conducted try to characterize the lesions using the ADC values trying to reach solid values for characterization and subgrouping which we can use especially for indeterminate lesions and for benign lesions which are radiologically characterized as Bosniak III and IV and underwent unnecessary nephrectomies. Objectives: Retrospective evaluation the efficiency of DWI and ADC values in characterization of benign, indeterminate, and malignant renal masses using 3T MRI. Results: We found the ADC values of the benign cysts are significantly higher than malignant cysts (3.03 versus 2.35 10 mm/s), Median, P=0.0001 with sensitivity and specificity 84% and 92%, however still no definite cut off values for indeterminate lesions. Conclusion: MRI ADC values can be used for differentiation of benign and malignant lesions with high sensitivity and specificity however still no definite cut off values for radiologically indeterminate cystic renal masses.

Contrast-enhanced ultrasound of the kidney: a single-institution experience.

Focal renal masses are typically evaluated by means of triphasic contrast-enhanced CT or MRI scan but use of iodinated contrast or gadolinium is unsuitable for some patients. Contrast-enhanced ultrasound (CEUS) is an imaging alternative in this scenario but has limited availability in Ireland. The aim of the study was to retrospectively evaluate experience with selective use of CEUS for non-invasive characterization of focal renal masses in a tertiary referral institution in Ireland, with a particular focus on cystic renal lesions and the influence of CEUS on final Bosniak classification and treatment outcomes. All cases of renal CEUS between 2009 and 2017 were identified. Imaging history, patient records, histopathology reports, urology conference notes, clinical follow-up details, details of lesion progression or stability on surveillance, biopsy and/or resection details and pre- and post-CEUS Bosniak scores were recorded. Thirty-one patients underwent renal CEUS (7 solid renal lesions, 21 cystic renal lesions and 3 'indeterminate' renal lesions). After CEUS, the CEUS-modified Bosniak score was upgraded in nine patients and downgraded in two patients. All three lesions upgraded from Bosniak III to IV were renal cell carcinomas. One of two lesions downgraded from Bosniak IV to III was resected (cystic nephroma) and the other showed no progression after 19months of surveillance. CEUS is a valuable alternative to CT in assessing complex cystic or solid renal lesions where iodinated CT contrast or gadolinium is inappropriate. CEUS can also refine the Bosniak category of atypical cystic renal lesions and help facilitate treatment decisions.

Differentiation of Solid Renal Tumors with Multiparametric MR Imaging.

Characterization of renal tumors is critical to determine the best therapeutic approach and improve overall patient survival. Because of increased use of high-resolution cross-sectional imaging in clinical practice, renal masses are being discovered with increased frequency. As a result, accurate imaging characterization of these lesions is more important than ever. However, because of the wide array of imaging features encountered as well as overlapping characteristics, identifying reliable imaging criteria for differentiating malignant from benign renal masses remains a challenge. Multiparametric magnetic resonance (MR) imaging based on various anatomic and functional parameters has an important role and adds diagnostic value in detection and characterization of renal masses. MR imaging may allow distinction of benign solid renal masses from several renal cell carcinoma (RCC) subtypes, potentially suggest the histologic grade of a neoplasm, and play an important role in ensuring appropriate patient management to avoid unnecessary surgery or other interventions. It is also a useful noninvasive imaging tool for patients who undergo active surveillance of renal masses and for follow-up after treatment of a renal mass. The purpose of this article is to review the characteristic MR imaging features of RCC and common benign renal masses and propose a diagnostic imaging approach to evaluation of solid renal masses using multiparametric MR imaging. ©RSNA, 2017.

Correlation of 99mTc-sestamibi uptake in renal masses with mitochondrial content and multi-drug resistance pump expression

Background99mTc-sestamibi single-photon emission computed tomography/computed tomography (SPECT/CT) has recently been explored for the characterization of indeterminate renal masses. As judged by increased intra-tumoral radiotracer uptake, we have previously reported the excellent diagnostic performance characteristics of this test for identifying benign/indolent oncocytomas and hybrid oncocytic/chromophobe tumors (HOCTs). In this study, we investigated potential molecular mechanisms underlying the discriminatory ability of 99mTc-sestamibi SPECT/CT for renal masses.Fifty renal masses imaged with 99mTc-sestamibi SPECT/CT prior to surgical resection were evaluated by immunohistochemistry for mitochondrial content and expression of the multi-drug resistance pump 1 (MDR1/P-gp). Immunohistochemical staining was scored semi-quantitatively, and results were compared across renal tumor histologies and correlated with 99mTc-sestamibi uptake.ResultsIn total, 6/6 (100%) and 2/2 (100%) HOCTs demonstrated strong mitochondrial content staining combined with low MDR1 staining. Clear cell renal cell carcinoma showed an opposite pattern with the majority having low mitochondrial (14/26, 54%) and high MDR1 staining (18/26, 69%). Other tumor types were more variable in staining pattern, although the staining pattern reliably predicted 99mTc-sestamibi uptake in almost all tumors except chromophobe renal cell carcinoma.ConclusionsOur findings confirm that renal tumors with high mitochondrial content and relatively low MDR pump expression activity accumulate 99mTc-sestamibi and allow for the accurate diagnosis of the benign/indolent tumor class that includes oncocytomas and HOCTs. For masses in which MDR activity outweighs the presence of mitochondria, the tumors appear cold on 99mTc-sestamibi SPECT/CT, allowing for high confidence in the diagnosis of renal cell carcinoma.

Role of Diffusion MRI in Evaluation of Renal Masses

Background: renal masses are being exposed more frequently in the last decades due to advances in cross sectional imaging such as CT and MR. Accurate characterization of renal masses is essential to ensure appropriate case management, to assist in staging and prognosis and to differentiate surgical lesions from nonsurgical lesions. However, in some cases there is an overlapping between the ADC values of benign and malignant masses. Thus, the use of ADC values alone may lead to inaccurate assessment of renal masses. Aim of the Study: to assess the roles of DWI in combination with quantitative ADC measurements the differentiation between benign and malignant renal masses. Conclusion: The combination of conventional MRI and ADC value in the diagnosis of renal masses can increase the diagnostic accuracy and considered of most value in cases where IV contrast agents are contraindicating.

Characterization of Incidental Renal Mass With Dual-Energy CT: Diagnostic Accuracy of Effective Atomic Number Maps for Discriminating Nonenhancing Cysts From Enhancing Masses.

The purpose of this study was to assess the diagnostic accuracy of effective atomic number maps reconstructed from dual-energy contrast-enhanced data for discriminating between nonenhancing renal cysts and enhancing masses. Two hundred six patients (128 men, 78 women; mean age, 64 years) underwent a CT renal mass protocol (single-energy unenhanced and dual-energy contrast-enhanced nephrographic imaging) at two different hospitals. For each set of patients, two blinded, independent observers performed measurements on effective atomic number maps from contrast-enhanced dual-energy data. Renal mass assessment on unenhanced and nephrographic images, corroborated by imaging and medical records, was the reference standard. The diagnostic accuracy of effective atomic number maps was assessed with ROC analysis. Significant differences in mean effective atomic numbers (Zeff) were observed between nonenhancing and enhancing masses (set A, 8.19 vs 9.59 Zeff; set B, 8.05 vs 9.19 Zeff; sets combined, 8.13 vs 9.37 Zeff) (p < 0.0001). An effective atomic number value of 8.36 Zeff was the optimal threshold, rendering an AUC of 0.92 (95% CI, 0.89-0.94), sensitivity of 90.8% (158/174 [95% CI, 85.5-94.7%]), specificity of 85.2% (445/522 [95% CI, 81.9-88.2%]), and overall diagnostic accuracy of 86.6% (603/696 [95% CI, 83.9-89.1%]). Nonenhancing renal cysts, including hyperattenuating cysts, can be discriminated from enhancing masses on effective atomic number maps generated from dual-energy contrast-enhanced CT data. This technique may be of clinical usefulness when a CT protocol for comprehensive assessment of renal masses is not available.

Characterization of indeterminate renal masses with molecular imaging: how do we turn potential into reality?

Characterization of indeterminate renal masses with molecular imaging: how do we turn potential into reality?

Can “Tumor-to-Cortex Echogenicity Ratio” Differentiate Angiomyolipomas from Other Hyper-Echoic Renal Masses

A retrospective study was performed to evaluate the diagnostic value of tumor-to-cortex echogenicity ratio (TCER) in the characterization of hyper-echoic renal masses. The radiology database was queried between 2012 and 2014 for hyper-echoic renal masses on the basis of defined exclusion and inclusion criteria. Each included mass was characterized as either an angiomyolipoma (AML) or a non-AML based on pre-defined criteria. The ratio of renal mass echogenicity to that of adjacent renal cortex (TCER) was calculated for each mass using commercially available software. A total of 70 masses in 65 patients were identified, including 49 AMLs. TCER values >2.26 were associated with a sensitivity and specificity of 81.6% and 71.4%, respectively, for diagnosis of AML. Moreover, TCER values >3.98 resulted in 100% specificity for AML diagnosis with a sensitivity of 28.6%. These findings suggest that the TCER may be a valuable tool for the characterization of hyper-echoic renal masses.

Feasibility of Contrast-Enhanced Intraoperative Ultrasound for Detection and Characterization of Renal Mass Undergoing Open Partial Nephrectomy.

To determine the feasibility of obtaining intraoperative contrast-enhanced ultrasound (CEUS) imaging in patients undergoing open partial nephrectomy for renal cancer. We hypothesize that the study was feasible and the addition of CEUS would improve lesion identification and characterization. The study population consisted of 10 patients with known renal mass scheduled for intraoperative ultrasound-guided open partial nephrectomy. After dissection and exposure of the kidney by the surgeon, an intraoperative pre- and post-CEUS was performed by the radiologist. Feasibility was defined as successful imaging in 8 of 10 patients with intraoperative CEUS. Image quality, lesion conspicuity/contrast, lesion vascularity, morphology, and size were assessed and graded with pre- and post-contrast images. Intraoperative ultrasound was successfully acquired in 10 of 11 patients for renal mass detection and characterization. One study was canceled intraoperatively as a result of clinical complications related to a difficult surgery. Tumor size ranged from 1.3 to 4.2 cm. All lesions were solid. No additional lesions were found on CEUS compared with baseline imaging. Image quality post-contrast ranged from acceptable to excellent. There were no adverse events recorded for all 10 patients. In our feasibility study consisting of 10 patients, CEUS for detection and characterization of renal mass undergoing open partial nephrectomy was feasible and safe. Because intraoperative ultrasound during open partial nephrectomy can affect the extent of surgery, CEUS can be used to help detect and characterize renal mass for surgical planning/resection intraoperatively.

Renal tumors with low signal intensities on T2-weighted MR image: radiologic-pathologic correlation.

Accurate characterization of renal masses is essential for ensuring appropriate management. Low T2 signal intensity is a common feature of papillary renal cell carcinoma and fat-poor angiomyolipoma. Nonetheless, other types of renal cell carcinoma, oncocytoma, hemangioma, lymphoma, leiomyoma, and urothelial cell carcinoma also can show low signal intensities on T2-weighted imaging (T2WI). Histopathologic features that can lead to low T2 signal intensities in renal tumors include smooth muscle component, papillary architecture, a high nucleus-to-cytoplasm ratio, and hemorrhage. To establish an appropriate differential diagnosis for renal tumors on MRI, it is necessary to understand the relationship between the MR signal intensities and the histopathologic and morphologic features, in addition to contrast enhancement patterns and diffusion characteristics of the tumors.

CEUS of Problematic Renal Masses: Comparison with CECT and CEMRI

Ultrasound (US) is often the first-line imaging modality in the evaluation of the renal masses. If the findings of a renal mass do not meet all of US criteria of a simple cyst, it should be characterized further. Usually characterization of indeterminate renal masses is well done with CT or MRI, but sometimes it is inconclusive on these imaging techniques. In thoses cases and in patients to whom radiation exposure or use of iodine or gadolinium contrast agents is undesirable, contrast-enhanced US (CEUS) may be a valuable alternative to evaluate those problematic renal masses. CEUS may replace CECT or CEMRI if the patient has marginal or poor renal function, hypersensitivity to iodine contrast agent, or fear of radiation exposure. CEUS has long history in medical US but drew attention only recently. With the first generation microbubble agents several studies showed added value of CEUS as compared to the conventional Doppler US. We reported that CEUS provided better visualization of tumor vascularity in indeterminate cystic renal lesions than other imaging modalities using a first-generation agtent. The most important limitation of the first generation agent was that it could not provide an enough duration of contrast enhancing effect. With introduction of the second generation microbubble agents with better stability and duration of contrast effect, CEUS examination became a practical alternative of CECT or CEMRI in evaluation of problematic renal masses. We do not think that CEUS will be used routinely in US examination of renal masses like contrast enhancement is routine in CT for renal masses. However, we are sure that CEUS will be a valuable imaging technique if it is used in well selected cases of problematic renal masses. In evaluating problematic renal masses, CEUS may reveal findings that were not seen or confirm findings equivocal at other imaging studies. Results of CEUS can be analyzed qualitatively as to the presence or absence of enhancement, vascular pattern and heterogeneity etc. Quantitative analysis can be done on peak intensity, time to peak, and rate of wash-in and wash-out, etc.

Office-based Ultrasound-guided Renal Core Biopsy Is Safe and Efficacious in the Management of Small Renal Masses

To evaluate the safety and efficacy of ultrasound (US)-guided percutaneous renal mass biopsy (RMB) performed in the office setting by urologists. This is a retrospective study involving patients who underwent office-based US-guided percutaneous RMB between April 2010 and October 2015. Baseline vital signs and US were performed prior to the procedure. Patients were then observed for 1hour after the procedure and repeat vital signs and US were performed. Hemodynamically stable patients who did not develop hematoma were discharged. In 108 patients, 70 (64.8%) were male, median age was 69.5 years, and median mass size was 3.3 cm (interquartile range: 2.5-4.6). Biopsy yield was as follows: 72 (66.7%) had renal cell carcinoma, 14 (13.0%) had benign renal parenchyma, 11 (10.2%) had oncocytoma, 6 (5.6%) had angiomyolipoma, 2 (1.9%) had lymphoma, and 3 (2.8%) had other disease. The initial nondiagnostic rate was 14 of 108 (13.0%). There were 28 of 108 (25.9%) patients observed whereas 79 of 108 (73.2%) received surgery or ablative therapy. Final pathology was concordant with biopsy results in 66 of 68 (97.1%) cases. Three patients experienced a grade I Clavien-Dindo surgical complication, all of which were managed conservatively. Office-based US-guided RMB is safe and efficacious in the management of appropriately selected SRM. It potentially offers improved dynamic characterization of solid renal mass, greater convenience to patients, as well as cost savings. Further studies are needed to evaluate this promising technique.

Characterization of Renal Masses by Ultrasound.

Characterization of Renal Masses by Ultrasound.

Management of incidental renal masses: Time to consider contrast-enhanced ultrasonography.

Proliferation of imaging studies for different clinical purposes and continuous improvement of imaging technology have led to an increasing number of incidental findings of renal masses. It is estimated that over 50% of patients older than 50 years have at least one renal mass. The majority of incidental renal masses are simple cysts that can be easily diagnosed by conventional ultrasonography. However, some incidental renal masses are not simple cysts, and differentiation between benign and malignant entities requires further imaging modalities. In the past, multiphase contrast-enhanced computed tomography and magnetic resonance imaging were considered the primary imaging modalities used to characterize and stage complex cystic and solid renal lesions. Currently, contrast-enhanced ultrasonography represents a novel alternative to contrast-enhanced computed tomography and magnetic resonance imaging. Contrast-enhanced ultrasonography employs microbubble contrast agents that allow the study of different enhancement phases of the kidney without risk of nephrotoxicity and radiation exposure. The diagnostic accuracy of contrast-enhanced ultrasonography in the characterization of complex renal cysts is comparable to that of computed tomography and magnetic resonance imaging, and several studies have demonstrated its reliability also in identifying solid lesions such as pseudotumors, typical angiomyolipomas, and clear cell renal carcinomas. Considering the high incidence of incidental renal masses and the need for rapid and reliable diagnosis, contrast-enhanced ultrasonography could be proposed as the first step in the diagnostic work-up of renal masses because of its safety and cost effectiveness. In this paper, we propose a diagnostic algorithm for the characterization of cystic and solid renal masses.

Role of US Contrast Agents in the Assessment of Indeterminate Solid and Cystic Lesions in Native and Transplant Kidneys.

Ultrasonography (US) is often the initial imaging modality employed in the evaluation of renal diseases. Despite improvements in B-mode and Doppler imaging, US still faces limitations in the assessment of focal renal masses and complex cysts as well as the microcirculation. The applications of contrast-enhanced US (CEUS) in the kidneys have dramatically increased to overcome these shortcomings with guidelines underlining their importance. This article describes microbubble contrast agents and their role in renal imaging. Microbubble contrast agents consist of a low solubility complex gas surrounded by a phospholipid shell. Microbubbles are extremely safe and well-tolerated pure intravascular agents that can be used in renal failure and obstruction, where computed tomographic (CT) and magnetic resonance (MR) imaging contrast agents may have deleterious effects. Their intravascular distribution allows for quantitative perfusion analysis of the microcirculation, diagnosis of vascular problems, and qualitative assessment of tumor vascularity and enhancement patterns. Low acoustic power real-time prolonged imaging can be performed without exposure to ionizing radiation and at lower cost than CT or MR imaging. CEUS can accurately distinguish pseudotumors from true tumors. CEUS has been shown to be more accurate than unenhanced US and rivals contrast material-enhanced CT in the diagnosis of malignancy in complex cystic renal lesions and can upstage the Bosniak category. CEUS can demonstrate specific enhancement patterns allowing the differentiation of benign and malignant solid tumors as well as focal inflammatory lesions. In conclusion, CEUS is useful in the characterization of indeterminate renal masses and cysts.

DWI for Renal Mass Characterization: Systematic Review and Meta-Analysis of Diagnostic Test Performance.

The objective of our study was to perform a systematic review and meta-analysis of the test performance of DWI in the characterization of renal masses. We performed searches of three electronic databases for studies on renal mass characterization using DWI. Methodologic quality was assessed for each study. We quantitatively analyzed test performance for three clinical problems: first, benign versus malignant lesions; second, clear cell renal cell carcinoma (RCC) versus other malignancies; and, third, high-versus low-grade clear cell RCCs. We summarized performance as a single pair of sensitivity and specificity values or a summary ROC curve. The studies in the literature were limited in both quantity and quality. For classification of benign versus malignant lesions, four studies with 279 lesions yielded a single summary estimate of 86% sensitivity and 78% specificity. For differentiation of clear cell RCC from other malignancies, five studies showed marked heterogeneity not conducive to meta-analysis. For differentiation of high-from low-grade clear cell RCCs, three studies with 110 lesions showed a threshold effect appropriate for summary ROC construction: The AUC was 0.83. Evidence suggests moderate accuracy of DWI for the prediction of malignancy and high-grade clear cell cancers, whereas DWI performance for ascertaining clear cell histologic grade remains unclear. To develop DWI as a noninvasive approach for the evaluation of solid renal masses, prospective studies with standardized test parameters are needed to better establish DWI performance and its impact on patient outcomes.

Comparison between computed tomography multislice and high-field magnetic resonance in the diagnostic evaluation of patients with renal masses.

Renal masses are a common finding in diagnostic imaging; these lesions usually are solid or cystic, benign or malignant, and the correct diagnosis may be difficult. The aim of our study was the comparison of multi-slice computed tomography (MSCT) and high-field magnetic resonance (MR) in the diagnostic evaluation of renal masses. We studied 29 patients, 16 men and 13 women aged 8-85 years (mean 61±17 years) with histo-cytological diagnosis of renal masses (n=31), of which the majority (74%; n=23) was represented by malignant lesions [renal cell carcinoma (Ca) =16, chromophobe renal cell Ca =2, squamous cell Ca =1, urothelial Ca =2, lymphoma =1, Wilms tumor =1]; the remaining 8 masses (26%) were benign (pyelonephritis =2, simple cyst =1, hematic cyst =1, lipoma =1 and oncocytoma =3). All patients underwent MSCT and MR (3.0 Tesla) before and after contrast injection; the images were evaluated in double-blind by two expert radiologists. The results of the images were then compared with the histo-cytological data to calculate the values of diagnostic accuracy for both methods in the identification and characterization of renal masses. The benign or malignant nature of the lesions was established according to the regularity of the margins, presence or absence of significant contrast enhancement, infiltration of perirenal fat and vascular invasion. The concordance of the results of the two imaging techniques was then calculated using the coefficient Kappa Cohen. For both identification and characterization of renal masses, MSCT and MR showed comparable values of diagnostic accuracy with a significant concordance (k=1); in particular, the diagnostic accuracy of MSCT/MR was 100%/100% for lesion identification, 90%/90% for lesion characterization in terms of benign or malignant nature, 97%/97% for the evaluation of lesion edges, 90%/90% for the assessment of lesion contrast enhancement, 93%/93% for the evaluation of peri-renal fat infiltration and 96%/96% for the evaluation of vascular infiltration. Only in three cases of oncocytoma the two imaging methods were both inaccurate for diagnosis of benignity classifying the lesions as probably malignant on the basis of the absence of central scar and of dynamic contrast enhancement pattern. The results of our study show comparable diagnostic accuracy of computed tomography (CT) and MR for the identification and characterization of expansive renal lesions. High-field MR is, therefore, a valid alternative to MSCT in the evaluation of renal masses avoiding exposure to ionizing radiation.

CT Urography: An Update in Imaging Technique

For decades, traditional IVU studies have been the mainstay in the investigation of urinary tract calculi and obstruction. However, they have been largely superseded by non-contrast CT in the present day. The use of contrast material further expands the utility of CT in the evaluation of urinary tract disease, allowing detection and characterization of renal masses and urothelial lesions. In this review article, we discuss the development and current role of CT urography as the complete imaging investigation in the genitourinary system. Conventional multiphasic protocols and split-bolus techniques for radiation dose reduction are considered. We then focus on how recent technological advances have allowed dual-energy CT to play a complementary role in CT evaluation of the genitourinary system, allowing stone and renal mass characterization, as well as creation of virtual unenhanced datasets. The use of associated post-processing software applications in the clinical context is illustrated.

Cross-sectional imaging evaluation of renal masses

Cross-sectional imaging modalities including multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) are the diagnostic standard in detection, characterization, and staging of renal masses due to their high sensitivity and specificity. Currently, most renal masses are incidentally diagnosed by imaging for other medical reasons. Recent developments have improved image acquisition with high resolution, while simultaneously reducing radiation dose. CT imaging is the most accessible cross-sectional imaging method and is, therefore, the standard technique. MRI is indicated in patients who are allergic to intravenous CT contrast medium, in patients with renal insufficiency, or in younger patients. Further characterization of renal masses is possible with functional imaging including dual energy CT, perfusion CT, or diffusion-weighted MRI. Contrast-enhanced ultrasound allows detection of even subtle enhancement in hypovascular lesions with high sensitivity and can add valuable information to CT and MRI studies.