Contrast-enhanced ultrasound for differentiating benign from malignant solid small renal masses: comparison with contrast-enhanced CT.
PURPOSE
The study aimed to compare the diagnostic efficiency of contrast-enhanced ultrasound (CEUS) with that of contrast-enhanced computed tomography (CECT) in the evaluation of benign and malignant small renal masses (SRMs) (<4 cm) confirmed by pathology.


METHODS
A total of 118 patients with 118 renal masses smaller than 4 cm diagnosed by both CEUS and CECT were enrolled in this study, including 25 benign lesions and 93 malignant lesions. All lesions were confirmed by histopathologic diagnosis after surgical resection. The diagnostic imaging studies of the patients were retrospectively reviewed by two independent ultrasonologists and two independent radiologists blinded to the CT or ultrasound findings and final histological results. All lesions on both CEUS and CECT were independently scored on a 3-point scale (1: benign, 2: equivocal, and 3: malignant). The concordance between interobserver agreement was interpreted using a weighted kappa statistic. The diagnostic efficiency of the evaluation of benign and malignant lesions was compared between CEUS and CECT.


RESULTS
All the 118 included lesions were detected by both CEUS and CECT. In CEUS and CECT imaging evaluation of the 118 lesions, the weighted kappa value interpreting the concordance between interobserver agreement was 0.89 (95% CI 0.79-0.98) and 0.93 (95% CI 0.87-0.99), respectively. Both CEUS and CECT demonstrated good diagnostic performance in differential diagnosis of benign and malignant SRMs with sensitivity of 93.5% and 89.2%, specificity of 68% and 76%, PPV of 91.6% and 93.3%, NPV of 73.9% and 65.5%, and AUC of 0.808 and 0.826, respectively. There was no statistically significant difference in any of the diagnostic performance indices between these two methods (P > 0.05). However, the qualitative diagnosis of small papillary renal cell carcinoma (RCC) by CEUS was significantly better than that by CECT (P < 0.05), while there was no significant difference in qualitative diagnostic accuracy on other histotypes of SRMs between CEUS and CECT (P > 0.05).


CONCLUSIONS
Both CEUS and CECT imaging modalities are effective for the differential diagnosis of benign and malignant SRMs. Furthermore, CEUS may be more effective than CECT for the qualitative diagnosis of small papillary RCC.
['Wei|Shu-Ping|SP|', 'Xu|Chao-Li|CL|', 'Zhang|Qing|Q|', 'Zhang|Qi-Rui|QR|', 'Zhao|Yan-E|YE|', 'Huang|Peng-Fei|PF|', 'Xie|Ying-Dong|YD|', 'Zhou|Chang-Sheng|CS|', 'Tian|Fu-Li|FL|', 'Yang|Bin|B|']
D000328:Adult D000368:Aged D003287:Contrast Media D003937:Diagnosis, Differential D005260:Female D006801:Humans D007680:Kidney Neoplasms D008297:Male D008875:Middle Aged D010743:Phospholipids D012189:Retrospective Studies D013459:Sulfur Hexafluoride D014057:Tomography, X-Ray Computed D018615:Ultrasonography, Doppler, Color
Contrast-enhanced ultrasound Small renal mass Contrast-enhanced computed tomography Differential diagnosis Microbubbles