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Comparing Quantitative Immunohistochemical Markers of Angiogenesis to Contrast‐Enhanced Subharmonic Imaging
Author(s) -
Gupta Aditi,
Forsberg Mark A.,
Dulin Kelly,
Jaffe Samantha,
Dave Jaydev K.,
Halldorsdottir Valgerdur G.,
Marshall Andrew,
Forsberg Anya I.,
Eisenbrey John R.,
Machado Priscilla,
Fox Traci B.,
Liu Ji-Bin,
Forsberg Flemming
Publication year - 2016
Publication title -
journal of ultrasound in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 91
eISSN - 1550-9613
pISSN - 0278-4297
DOI - 10.7863/ultra.15.05024
Subject(s) - medicine , angiogenesis , immunohistochemistry , contrast (vision) , pathology , subharmonic , artificial intelligence , computer science , physics , nonlinear system , quantum mechanics
Objectives Different methods for obtaining tumor neovascularity parameters based on immunohistochemical markers were compared to contrast‐enhanced subharmonic imaging (SHI). Methods Eighty‐five 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, North Billerica, MA) was injected, and SHI was performed using a modified Sonix RP scanner (Analogic Ultrasound, Richmond, British Columbia, Canada) with a L9‐4 linear array (transmitting/receiving frequencies, 8/4 MHz). Afterward, specimens were stained for endothelial cells (CD31), vascular endothelial growth factor (VEGF), and cyclooxygenase 2 (COX‐2). Tumor neovascularity was assessed in 4 different ways using a histomorphometry system (×100 magnification: (1) over the entire tumor; (2) in small sub–regions of interest (ROIs); (3) in the tumor periphery and centrally; and (4) in 3 regions of maximum marker expression (so‐called hot spots). Results from specimens and from SHI were compared by linear regression. Results Fifty‐four rats (64%) showed tumor growth, and 38 were successfully imaged. Subharmonic imaging depicted the tortuous morphologic characteristics of tumor neovessels and delineated small areas of necrosis. The immunohistochemical markers did not correlate with SHI measures over the entire tumor area or over small sub‐ROIs ( P > .18). However, when the specimens were subdivided into central and peripheral regions, COX‐2 and VEGF correlated with SHI in the periphery ( r = −0.42; P = .005; and r = −0.32; P = .049, respectively). Conclusions When comparing quantitative contrast measures of tumor neovascularity to immunohistochemical markers of angiogenesis in xenograft models, ROIs corresponding to the biologically active region should be used to account for tumor heterogeneity.