Preoperative assessment of gastric cancer vascularity by flash echo imaging

Tumor vascularity as indicated by immunohistochemical staining is a significant prognostic factor in gastric and other cancers. Non-invasive preoperative assessment of the vascularity of gastric cancers has not been possible. We aim to determine the reliability of harmonic flash echo imaging (FEI) for assessment of vascularity of gastric cancers by comparison with CD34 staining of resected specimens.

Twelve patients undergoing surgical resection of advanced gastric cancer were studied. An ultrasound system transmitting ultrasound pulses at 2.3 MHz and receiving them at 4.6 MHz (second harmonic image) was used for harmonic FEI. Approximately 30 s after intravenous injection of ultrasonic contrast medium (SHU 508A, Levovist), second harmonics (4.6 MHz) emitted from microbubbles were obtained to enhance the B-mode images. Using the tumor image showing strongest enhancement in each FEI series, regions of interest were determined to measure mean echo intensity in the tumor. Immunohistochemistry using antibodies against CD34 was carried out in resected specimens. Tumor vascularity was determined by counting stained microvessels.

A significant positive correlation was noted between sonographic amplitude determined preoperatively by FEI analysis and number of CD34-stained microvessels in tumor specimens (r = 0.869, P = 0.004).

Vascularity of gastric cancers now can be evaluated non-invasively by harmonic FEI.