Characterization of renal cell carcinoma using agent detection imaging: comparison with gray-scale US

Qualitative and quantitative analysis of solid renal tumors by high-frame-rate contrast-enhanced ultrasound

OBJECTIVE

To analyze the characteristics of high-frame-rate contrast-enhanced ultrasound (H-CEUS) in solid renal tumors using qualitative and quantitative methods.

METHODS

Seventy-five patients who underwent preoperative conventional ultrasound (US), conventional contrast-enhanced ultrasound (C-CEUS), and H-CEUS examination of renal tumors were retrospectively analyzed, with a total of 89 renal masses. The masses were divided into the benign (30 masses) and malignant groups (59 masses) based on the results of enhanced computer tomography and pathology. The location, diameter, shape, border, calcification, and color doppler blood flow imaging (CDFI) of the lesions were observed by US, and the characteristics of the C-CEUS and H-CEUS images were qualitatively and quantitatively analyzed. The χ² test or Fisher's exact probability method was used to compare the US image characteristics between the benign and malignant groups, and the image characteristics of C-CEUS and H-CEUS between the benign and malignant groups. Moreover, the nonparametric Mann-Whitney test was used to compare the differences in C-CEUS and H-CEUS time-intensity curve (TIC) parameters.

RESULTS

Significant differences in gender, surgical approach, echogenicity, and CDFI were observed between the malignant and benign groups (p = 0.003, < 0.001, < 0.001, = 0003). Qualitative analysis also revealed significant differences in the mode of wash-out and fill-in direction between C-CEUS and H-CEUS in the malignant group (p = 0.041, 0.002). In addition, the homogeneity of enhancement showed significant differences between the two contrast models in the benign group (p = 0.009). Quantitative analysis indicated that the TIC parameters peak intensity (PI), deceleration time (DT) /2, area under the curve (AUC), and mean transition time (MTT) were significantly lower in the H-CEUS model compared to the C-CEUS model in both the benign and malignant groups. (all p < 0.001). In contrast, ascending slope of rise curve (AS) was significantly higher in the H-CEUS model compared to the C-CEUS model in the malignant group (p = 0.048).

CONCLUSIONS

In renal tumors, H-CEUS shows clearer internal enhancement of the mass and the changes in the wash-out period. The quantitative TIC parameters PI, DT/2, AUC, and MTT were lower in H-CEUS compared to C-CEUS. Both the quantitative and qualitative analyses indicated that H-CEUS better displays the characteristics of solid renal masses compared with C-CEUS.

Gray-Scale, Color Doppler, Spectral Doppler, and Contrast-Enhanced Renal Artery Ultrasound: Imaging Techniques and Features

Renal artery stenosis (RAS) is increasingly being detected in elderly patients as life expectancy increases. RAS induces hypertension or reduces renal function. Computed tomography or magnetic resonance angiography are objective in detecting RAS but may cause iodine-induced nephrotoxicity or nephrogenic systemic fibrosis in patients with RAS. Ultrasound (US) is, by contrast, a noninvasive and real-time imaging modality useful in patients with reduced renal function. Renal US is not as sensitive for detecting RAS because this technique indirectly assesses the renal artery by analyzing intrarenal hemodynamic changes. Although, ideally, US would be used to directly evaluate the renal artery, its current utility for RAS detection remains unclear. The purpose of this review is to introduce how to assess renal artery with US, to describe imaging features of renal artery US, to compare renal artery US and renal US, and to show how to perform work-up in patients in whom RAS is suspected.

Differentiation of subtypes of renal cell carcinoma with contrast-enhanced ultrasonography

We aimed to assess the difference of enhancement patterns among the three RCC subtypes with contrast-enhanced ultrasound (CEUS). Two hundreds cases of pathologically proved clear cell renal cell carcinomas (ccRCC), 58 papillary renal cell carcinomas (pRCC) and 51 chromophobe renal cell carcinomas (chRCC) underwent preoperative conventional ultrasound and CEUS. The wash-in and wash-out pattern, peak enhancement degree and homogeneity, and the presence of pseudocapsule were evaluated by two blinded observers respectively. The interreader agreement in the characterization of CEUS features between two observers was good (κ  = 0.649-0.775). Compared with pRCCs and chRCCs, ccRCCs demonstrated higher frequency of simultaneous wash-in pattern, hyperenhancement and heterogeneity with necrotic areas. Most pRCCs and chRCCs manifested hypoenhancement, homogeneity, fast wash-out and presence of pseudocapsule. The only difference we obtained between pRCC and chRCC was the wash-in pattern, with slow wash-in in pRCC and simultaneous wash-in in chRCC. In small lesions with long diameter≤3 cm, the majority of the three subtypes of RCC showed homogeneous enhancement and there was no difference among them. CEUS was a useful method to preoperatively differentiate the ccRCC from non-ccRCC subtypes. There were no distinguishing features identifid on CEUS that allowed reliable differentiation of pRCC from chRCC.

Qualitative and quantitative analysis with contrast-enhanced ultrasonography: diagnosis value in hypoechoic renal angiomyolipoma

Objective

To evaluate the value of enhancement features and quantitative parameters of contrast-enhanced ultrasonography (CEUS) in differentiating solid hypoechoic renal angiomyolipomas (AMLs) from clear cell renal cell carcinomas (ccRCCs).

Materials and Methods

We analyzed the enhancement features and quantitative parameters of CEUS in 174 hypoechoic renal masses (32 AMLs and 142 ccRCCs) included in the study.

Results

Centripetal enhancement pattern was more common in AMLs than in ccRCCs on CEUS (71.9% vs. 23.2%, p < 0.001). At peak enhancement, all AMLs showed homogeneous enhancement (100% in AML, 27.5% in ccRCCs; p < 0.001). Quantitative analysis showed no significant difference between rise time and time to peak. Tumor-to-cortex (TOC) enhancement ratio in AMLs was significantly lower than that in ccRCCs (p < 0.001). The criteria of centripetal enhancement and homogeneous peak enhancement together with TOC ratio < 91.0% used to differentiate hypoechoic AMLs from ccRCCs resulted in a sensitivity and specificity of 68.9% and 95.8%, respectively.

Conclusion

Both qualitative and quantitative analysis with CEUS are valuable in the differential diagnosis of hypoechoic renal AMLs from ccRCCs.

Quantification of enhancement of renal parenchymal masses with contrast-enhanced ultrasound

The purpose of this study was to investigate the value of quantitative assessment of enhancement in diagnosing renal cell carcinoma (RCC) with contrast-enhanced ultrasound (CEUS). A total of 73 solid renal parenchymal masses underwent both conventional ultrasound and CEUS. We compared the difference in maximum diameters on conventional ultrasound and CEUS between the benign and malignant groups. Enhancement features derived from a time-intensity curve were also analyzed. The diameters of renal cancer were found to be larger on CEUS than on conventional ultrasound (p < 0.05). When cutoff values of 4.74 s for washout time and 8.52% for enhancement intensity at 60 s for diagnosing RCCs were applied, the sensitivity, specificity and area under the receiver operating characteristic curve were 67.3%, 95.2%, 86.5% and 65.4%, 81.0%, 68.4%, respectively. The sensitivity and specificity for these two enhancement characteristics combined as a criterion for differentiating RCCs from benign lesions were 44.0% and 99.1%, respectively. Early washout in the area of maximal intensity in the interior of the lesion and prolonged washout in the whole area of the lesion are specific CEUS manifestations suggestive of RCC.

Renal oncocytoma: contrast-enhanced sonographic features

OBJECTIVES

The purpose of this study was to illustrate the features of renal oncocytoma on contrast-enhanced sonography.

METHODS

Five cases of surgical pathologically proven renal oncocytoma were retrospectively reviewed and analyzed in this study. The 5 patients studied included 3 men and 2 women with a mean age of 52.3 years (range, 32-66 years). All patients underwent conventional and contrast-enhanced sonographic examinations before surgery. The sonographic features, enhancement pattern, and dynamic perfusion change of the tumors and renal parenchyma in vascular phases were evaluated and compared to computed tomography.

RESULTS

On grayscale sonography, renal oncocytomas appeared as solitary hypoechoic or isoechoic masses originating from the renal cortex measuring 2 to 6 cm with a well-defined margin. Color Doppler flow imaging showed rich blood flow signals in the periphery and striplike blood flow signals within the masses. On contrast-enhanced sonography, the features of these tumors included early enhancement, hyperenhancement, and fast wash-out compared to the adjacent renal cortex. There were irregular nonenhanced areas seen in the center of the masses (n = 3) and nonenhanced thin rims seen in the periphery (n = 5). Macroscopically, the well-marginated tumors were yellowish brown with a tender texture and were located in the renal cortex. Central irregularly shaped fibrous scars were seen in 3 tumors, consistent with nonenhanced areas on contrast-enhanced imaging.

CONCLUSIONS

Contrast-enhanced sonography can provide valuable hemodynamic information on renal oncocytoma, which may help in making a differential diagnosis of this benign renal tumor in clinical practice.

Minimal fat renal angiomyolipoma: the initial study with contrast-enhanced ultrasonography

We visualized minimal fat renal angiomyolipomas (AMLs) by contrast-enhanced ultrasonography (CEUS). Conventional ultrasound and CEUS images were retrospectively analyzed for solid minimal fat renal AML cases (n = 18) and solid renal cell carcinoma (RCC) cases (n = 105). We compared size, echogenicity and color flow signals with conventional ultrasound, and enhancement patterns with CEUS, in AMLs vs. RCCs. No significant differences in echogenicity and color flow signal existed between AMLs and RCCs using conventional ultrasound. With CEUS, slow centripetal enhancement in the cortical phase (83.3% of AMLs vs. 1.9% of RCCs) and homogeneous peak enhancement (100.0% of AMLs vs. 34.3% of RCCs) were valuable traits for differentiating these tumor types. These two CEUS-determined traits, combined, were differentiating criteria for minimal fat renal AMLs and RCCs; positive and negative predictive values were 100.0% and 97.2%, respectively. Slow centripetal enhancement in the cortical phase and homogeneous enhancement at peak are main features of CEUS-confirmed solid minimal fat renal AML.

Using Sonography to Characterize Renal Cell Carcinoma: Case Study of a Large Renal Mass

Renal cell carcinoma (RCC) is both the most common—and deadly—renal tumor in the adult population. It is categorized into various subtypes, with clear cell RCC being the most common of those. Sonography, in addition to other imaging modalities, is important in discovering, describing, staging, and ultimately predicting the outcome of RCC. This article presents a case study of a woman in her 60s diagnosed with late clear cell RCC with multiple metastases. It also addresses recent literature regarding outcomes for this disease.

Imaging of renal cell carcinoma: state of the art and recent advances

BACKGROUND AND AIM

Renal cell carcinoma (RCC) is the 13th most common cancer worldwide and accounts for 4% of all adult malignancies. Herein the state of the art and recent advances in cross-sectional radiological imaging applied to RCC are reviewed, including ultrasonography, computed tomography, magnetic resonance imaging, and positron emission tomography.

METHODS

Literature search of peer-reviewed papers published by October 2010.

RESULTS

In front of more conventional and widespread imaging tools, such as ultrasonography and computed tomography, an array of newer and attractive radiological modalities are under investigation and show promise to improve our ability to noninvasively detect renal tumors and its recurrences, accurately assess the extent of the disease, and reliably evaluate treatment response, particularly in the era of antiangiogenetic therapy.

CONCLUSIONS

Recent major advances in radiological imaging techniques have considerably improved our ability to diagnose, stage and follow-up RCC. Further studies are needed to evaluate the potential of most recent and still investigational imaging tools.

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.

Diagnostic efficacy of contrast-enhanced ultrasonography in solid renal parenchymal lesions with maximum diameters of 5 cm

OBJECTIVE

The purpose of this study was to evaluate the diagnostic efficacy of contrast-enhanced ultrasonography (CEUS) using a sulfur hexafluoride contrast agent and the cadence contrast pulse sequencing mode in differentiating solid renal parenchymal lesions (SRPLs) with a maximum diameter of 5 cm.

METHODS

Seventy-one patients with 72 SRPLs with a maximum diameter of 5 cm underwent conventional ultrasonographic and CEUS examinations in our department. The final diagnoses were 44 renal cell carcinomas (RCCs; confirmed by pathologic examination), 24 renal angiomyolipomas (4 by pathologic examination and 20 by computed tomography, magnetic resonance imaging, and follow-up studies), 1 oncocytoma (by pathologic examination), 2 hypertrophied columns of Bertin, and 1 renal abscess (both by computed tomography, magnetic resonance imaging, and follow-up studies). Three observers who were blinded to other results and the final diagnoses reviewed the conventional ultrasonographic and CEUS images.

RESULTS

Hyperenhancement in the late phase (30-90 seconds after agent injection) was the most important finding for predicting SRPLs with a maximum diameter of 5 cm to be RCCs. With this criterion, the specificity and sensitivity for diagnosing solid RCCs (<or= 5 cm) were 96.4% and 77.3%, respectively. Heterogeneous enhancement was another valuable finding suggestive of RCCs. Most renal angiomyolipomas were homogeneously enhanced with hypoenhancement in the arterial and late phases. Hypertrophied columns of Bertin could be reliably differentiated on CEUS; however, there was an overlap of CEUS appearances between some benign lesions and hypovascular RCCs.

CONCLUSIONS

Contrast-enhanced ultrasonography could be an effective and necessary examination for differentially diagnosing SRPLs with a maximum diameter of 5 cm.