Dahibawkar Manasi, Forsberg Mark A, Gupta Aditi, Jaffe Samantha, Dulin Kelly, Eisenbrey John R, Halldorsdottir Valgerdur G, Forsberg Anya I, Dave Jaydev K, Marshall Andrew, Machado Priscilla, Fox Traci B, Liu Ji-Bin, Forsberg Flemming
Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA; School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA.
Yale University, New Haven, CT 06520, USA.
Ultrasonics. 2015 Sep;62:50-5. doi: 10.1016/j.ultras.2015.04.012. Epub 2015 May 5.
This project compared quantifiable measures of tumor vascularity obtained from contrast-enhanced high frequency (HF) and low frequency (LF) subharmonic ultrasound imaging (SHI) to 3 immunohistochemical markers of angiogenesis in a murine breast cancer model (since angiogenesis is an important marker of malignancy and the target of many novel cancer treatments). Nineteen athymic, nude, female rats were implanted with 5×10(6) breast cancer cells (MDA-MB-231) in the mammary fat pad. The contrast agent Definity (Lantheus Medical Imaging, N Billerica, MA) was injected in a tail vein (dose: 180μl/kg) and LF pulse-inversion SHI was performed with a modified Sonix RP scanner (Analogic Ultrasound, Richmond, BC, Canada) using a L9-4 linear array (transmitting/receiving at 8/4MHz in SHI mode) followed by HF imaging with a Vevo 2100 scanner (Visualsonics, Toronto, ON, Canada) using a MS250 linear array transmitting and receiving at 24MHz. The radiofrequency data was filtered using a 4th order IIR Butterworth bandpass filter (11-13MHz) to isolate the subharmonic signal. After the experiments, specimens were stained for endothelial cells (CD31), vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2). Fractional tumor vascularity was calculated as contrast-enhanced pixels over all tumor pixels for SHI, while the relative area stained over total tumor area was calculated from specimens. Results were compared using linear regression analysis. Out of 19 rats, 16 showed tumor growth (84%) and 11 of them were successfully imaged. HF SHI demonstrated better resolution, but weaker signals than LF SHI (0.06±0.017 vs. 0.39±0.059; p<0.001). The strongest overall correlation in this breast cancer model was between HF SHI and VEGF (r=-0.38; p=0.03). In conclusion, quantifiable measures of tumor neovascularity derived from contrast-enhanced HF SHI appear to be a better method than LF SHI for monitoring angiogenesis in a murine xenograft model of breast cancer (corresponding in particular to the expression of VEGF); albeit based on a limited sample size.
本项目在小鼠乳腺癌模型中，将通过对比增强高频（HF）和低频（LF）亚谐波超声成像（SHI）获得的肿瘤血管量化指标，与3种血管生成的免疫组化标记物进行比较（因为血管生成是恶性肿瘤的一个重要标记物，也是许多新型癌症治疗的靶点）。19只无胸腺裸雌性大鼠在乳腺脂肪垫植入5×10⁶个乳腺癌细胞（MDA-MB-231）。通过尾静脉注射造影剂Definity（Lantheus Medical Imaging，美国马萨诸塞州比勒里卡）（剂量：180μl/kg），使用改良的Sonix RP扫描仪（Analogic Ultrasound，加拿大不列颠哥伦比亚省里士满）进行LF脉冲反转SHI，使用L9-4线性阵列（在SHI模式下以8/4MHz发射/接收），随后使用Vevo 2100扫描仪（Visualsonics，加拿大多伦多）进行HF成像，使用MS250线性阵列以24MHz发射和接收。使用四阶IIR巴特沃斯带通滤波器（11 - 13MHz）对射频数据进行滤波，以分离亚谐波信号。实验结束后，对标本进行内皮细胞（CD31）、血管内皮生长因子（VEGF）和环氧合酶-2（COX-2）染色。肿瘤血管分数计算为SHI中对比增强像素占所有肿瘤像素的比例，而从标本计算染色相对面积占总肿瘤面积的比例。使用线性回归分析比较结果。19只大鼠中，16只出现肿瘤生长（84%），其中11只成功成像。HF SHI显示出更好的分辨率，但信号比LF SHI弱（0.06±0.017对0.39±0.059；p<0.001）。在该乳腺癌模型中，总体相关性最强的是HF SHI与VEGF之间（r = -0.38；p = 0.03）。总之，在小鼠乳腺癌异种移植模型中，源自对比增强HF SHI的肿瘤新生血管量化指标似乎是比LF SHI更好的监测血管生成的方法（尤其对应VEGF的表达）；尽管基于有限的样本量。
