Evaluation of Renal Masses With Contrast-Enhanced Ultrasound: Initial Experience

Abstract

OBJECTIVE Nearly 25% of solid renal tumors are indolent cancer or benign and can be managed conservatively in selected patients. This prospective study was performed to determine whether preoperative IV microbubble contrast-enhanced ultrasound can be used to differentiate indolent and benign renal tumors from more aggressive clear cell carcinoma. SUBJECTS AND METHODS Thirty-four patients with renal tumors underwent preoperative gray-scale, color, power Doppler, and octafluoropropane microbubble IV contrast-enhanced ultrasound. Three blinded radiologists reading in consensus compared rate of contrast wash-in, grade and pattern of enhancement, and contrast washout compared with adjacent parenchyma. Contrast ultrasound findings were compared with surgical histopathologic findings for all patients. RESULTS The 34 patients had 23 clear cell carcinomas, three type 1 papillary carcinomas, one chromophobe carcinoma, one clear rare multilocular low-grade malignant tumor, two unclassified lesions, three oncocytomas, and one benign angiomyolipoma. The combination of heterogeneous lesion echotexture and delayed lesion washout had 85% positive predictive value, 43% negative predictive value, 48% sensitivity, and 82% specificity for predicting whether a lesion was conventional clear cell carcinoma or another tumor. Diminished lesion enhancement grade had 75% positive predictive value, 81% negative predictive value, 55% sensitivity, and 91% specificity for non–clear cell histologic features, either benign or low-grade malignant. Combining delayed washout with quantitative lesion peak intensity of at least 20% of kidney peak intensity had 91% positive predictive value, 40% negative predictive value, 63% sensitivity, and 80% specificity in the prediction of clear cell histologic features. CONCLUSION Ultrasound features of gray-scale heterogeneity, lesion washout, grade of contrast enhancement, and quantitative measure of peak intensity may be useful for differentiating clear cell carcinoma and non–clear cell renal tumors.

Dynamic Tissue Perfusion Measurement: A New Tool for Characterizing Renal Perfusion in Renal Cell Carcinoma Patients

“…The conventional color Doppler US has limitations in resolving intratumor vascularization [13]. Although contrast-enhanced US is an invasive procedure, it has already been successfully applied for measuring tissue perfusion in primary tumor lesions [14] or for monitoring therapy response [15]. …”

Histotype differentiation of hypo-echoic renal tumors on CEUS: usefulness of enhancement homogeneity and intensity

“…In previous study with qualitative CEUS analysis, they were reported to be hypo-enhanced throughout the CEUS progress [12]. In our study, their TOC ratio is the lowest compared with ccRCCs and AMLs, which may be attributed to the vascularized stalks of pRCCs, which are characterized by the presence of only small vessels without any enlarged vessels or arteriovenous shunts [11], and to the compact growth pattern of tumor cells in cRCCs [25]. However, there is no significant difference in TOC ratio between these histotypes.…”

“…The rich vascular network and alveolar architecture observed on histology renders the strong enhancement seen in ccRCCs [22]. Much effort has gone into quantitative analysis in the differentiation of ccRCC: for instance, Zhang et al [23] reported ccRCC to be the most hyper-enhanced tumor compared with pRCC, cRCC, and AML on CECT, and Gerst et al [11] also reported that the degree of enhancement in ccRCC was significantly higher than that in low-grade malignancy with CEUS. However, these studies enrolled only malignant lesions, or included only a relatively small cohort of benign tumors and those with different modalities.…”

“…Presently, contrast-enhanced ultrasound (CEUS) is being applied in the differential diagnosis of renal tumor histotypes by visualizing difference in vascular perfusion, and specific imaging features, such as slow centripetal and homogeneous enhancement in AMLs, hyperenhancement in ccRCCs [11], hypo-enhancement in pRCCs and cRCCs [12] which have been reported to be helpful in this field. However, these studies were based on a relative small number of cases, and involve only qualitative analysis of CEUS, which may be rather subjective.…”

Quantitative assessment of solid renal masses by contrast-enhanced ultrasound with time–intensity curves: how we do it

“…Accounting for 70% of all RCCs, the clear cell subtype is the most common, followed by papillary (10%-15%), chromophobe (5%), unclassified (4%), and other rare subtypes (<1%), including multilocular cystic, collecting duct, medullary, mucinous tubular and spindle cell, neuroblastoma-associated, Xp11.2 translocation-TFE3, and hybrid oncocytic tumor [associated with BirtHogg-Dube´(BHD)] [8-10]. Subtyping has prognostic significance, as clear cell, collecting duct, papillary type 2, and medullary can be aggressive, while papillary type 1, chromophobe, and multilocular cystic are more indolent [8,[10][11][12]. Subtyping can potentially alter management as well; while surgical resection remains the standard of treatment for RCC, in patients who are elderly, have multiple co-morbidities, or are otherwise poor surgical candidates, preoperative knowledge that a tumor is more likely to be a less aggressive RCC subtype may lead to consideration of ablation therapy or surveillance, rather than surgery.…”