RGD-Targeted Ultrasound Contrast Agent for Longitudinal Assessment of Hep-2 Tumor Angiogenesis In Vivo.

OBJECTIVE: To prepare arginine-glycine-aspartate (RGD)-targeted ultrasound contrast microbubbles (MBs) and explore the feasibility of their use in assessing dynamic changes in αvß3 integrin expression in a murine model of tumor angiogenesis. METHODS: RGD peptides were conjugated to the surfaces of microbubbles via biotin-avidin linkage. Microbubbles bearing RADfK peptides were prepared as controls. The RGD-MBs were characterized using an Accusizer 780 and optical microscopy. The binding specificity of the RGD-MBs for ανß3-expressing endothelial cells (bEnd.3) was demonstrated in vitro by a competitive inhibition experiment. In an in vivo study, mice bearing tumors of three different stages were intravenously injected with RGD-MBs and subjected to targeted, contrast-enhanced, high-frequency ultrasound. Subsequently, tumors were harvested and sectioned for immunofluorescence analysis of ανß3 expression. RESULTS: The mean size of the RGD-MBs was 2.36 ± 1.7 µm. The RGD-MBs showed significantly higher adhesion levels to bEnd.3 cells compared to control MBs (P < 0.01). There was rarely binding of RGD-MBs to αvß3-negative MCF-7 cells. Adhesion of the RGD-MBs to the bEnd.3 cells was significantly inhibited following treatment with anti-alpha(v) antibodies. The quantitative acoustic video intensity for high-frequency, contrast-enhanced ultrasound imaging of subcutaneous human laryngeal carcinoma (Hep-2) tumor xenografts was significantly higher in small tumors (19.89 ± 2.49) than in medium tumors (11.25 ± 2.23) and large tumors (3.38 ± 0.67) (P < 0.01). CONCLUSIONS: RGD-MBs enable noninvasive in vivo visualization of changes in tumor angiogenesis during tumor growth in subcutaneous cancer xenografts.

Meta-analysis of contrast-enhanced ultrasound for the differentiation of benign and malignant breast lesions.

BACKGROUND: Contrast-enhanced ultrasound (CEUS) is a non-invasive method for the assessment of breast lesions. The accuracy of CEUS in diagnosing of breast cancer has never been systematically assessed. PURPOSE: To determine the overall performance of CEUS in the differentiation of benign and malignant breast lesions using meta-analysis. MATERIAL AND METHODS: PubMed, Embase, Cochrane Library, and article references published before October 2012 were searched. Published studies that used histopathologic results as golden reference to assess the diagnostic performance of CEUS in patients suspected of having breast cancer and the data necessary to calculate the diagnostic results were included. The qualities of eligible studies for final meta-analysis were assessed by using the quality assessment of diagnostic studies (QUADAS) instrument. Sensitivity, specificity, summary receiver-operating characteristic (sROC) curves, and area under the curve were calculated to examine the diagnostic performance of CEUS. RESULTS: Of 16 eligible studies, 957 breast lesions were included in the original meta-analysis, among which heterogeneity arising from factors other than threshold effect was explored. Meta-regression analysis confirmed the contrast agent was the most significant factor cause of heterogeneity (P = 0.0012, relative diagnostic odds ratio [DOR] = 7.06). The use of perfluoro containing microbubbles (Sonovue or Optison) significantly increased the diagnostic precision compared with Levovist. The pooled weighted estimates of sensitivity and specificity for CEUS in the diagnosis of breast lesions were 0.86 (95% confidence interval [CI], 0.83, 0.89) and 0.79 (95% CI, 0.75, 0.83), respectively. CONCLUSION: CEUS has good sensitivity and specificity in the characterization of breast lesions and can potentially help to select suspicious breast mass for surgery.

Acoustic radiation force impulse imaging for non-invasive assessment of renal histopathology in chronic kidney disease.

OBJECTIVE: To investigate the stiffness values obtained by acoustic radiation force impulse (ARFI) quantification in assessing renal histological fibrosis of chronic kidney disease (CKD). METHODS: 163 patients with CKD and 32 healthy volunteers were enrolled between June 2013 and April 2014. ARFI quantification, given as shear wave velocity (SWV), was performed to measure renal parenchyma stiffness. Diagnostic performance of ARFI imaging and conventional ultrasound (US) were compared with histologic scores at renal biopsy. Intra- and inter-observer reliability of SWV measurement was analyzed. RESULTS: In CKD patients, SWV measurements correlated significantly with pathological parameters (r = -0.422--0.511, P<0.001), serum creatinine (r = -0.503, P<0.001), and glomerular filtration rate (r = 0.587, P<0.001). The mean SWV in kidneys with severely impaired (histologic score: ≥19 points) was significant lower than that mildly impaired (histologic score: ≤9 points), moderately impaired (histologic score: 10-18 points), and control groups (all P<0.001). Receiver operating characteristic (ROC) curves analyses indicated that the area under the ROC curve for the diagnosis of renal histological fibrosis using ARFI imaging was superior to these conventional US parameters. Using the optimal cut-off value of 2.65 m/s for the diagnosis of mildly impaired kidneys, 2.50 m/s for moderately impaired kidneys, and 2.33 m/s for severely impaired kidneys, the corresponding area under the ROC curves were 0.735, 0.744, and 0.895, respectively. Intra- and intre-observer agreement of SWV measurements were 0.709 (95% CI: 0.390-0.859, P<0.001) and 0.627 (95% CI: 0.233-0.818, P = 0.004), respectively. CONCLUSIONS: ARFI may be an effective tool for evaluating renal histological fibrosis in CKD patients.