We report photoacoustic microscopy (PAM) of arteriovenous (AV) shunts in early stage tumors in vivo, and develop a pattern recognition framework for computerized tumor detection. Here, using a high-resolution photoacoustic microscope, we implement a new blood oxygenation (sO(2))-based disease marker induced by the AV shunt effect in tumor angiogenesis. We discovered a striking biological phenomenon: There can be two dramatically different sO(2) values in bloodstreams flowing side-by-side in a single vessel. By tracing abnormal sO(2) values in the blood vessels, we can identify a tumor region at an early stage. To further automate tumor detection based on our findings, we adopt widely used pattern recognition methods and develop an efficient computerized classification framework. The test result shows over 80% averaged detection accuracy with false positive contributing 18.52% of error test samples on a 50 PAM image dataset.

Objective: To explore the effects of recombinant human endostatin (endostar, ES) and cisplatin on the growth of gastric cancer-transplanted tumor in nude mice and the expression of microvessel density (MVD).Methods: Human gastric cancer SGC-7901 cells were subcutaneously injected into the armpit of nude mice to prepare cancer-bearing nude mice. A total of 32 cancer-bearing nude mice were divided into four groups (each group with 8 mice). The four groups included control group and other three groups in which mice were treated with 5mg/kg of ES (group E), 5mg/kg of cisplatin (group Ci), and 5mg/kg of ES combined with 5mg/kg of cisplatin (group C), respectively. MVD was determined by immunohistochemistry, and the expressions of mRNA and protein of inhibitor of differentiation-1 (ID1) and vascular endothelial growth factor (VEGF) were detected with reverse transcription polymerase chain reaction (RT-PCR) and western blot, respectively. Apoptosis was observed with transmission electron microscope.Results: Compared with control group, the sizes and weights of tumors were significantly decreased in other three groups (all p < 0.05). MVD was significantly lower in groups E, Ci, and C than in control group, and in groups E and C than in group Ci (all p < 0.05). Compared with control group, the expressions of mRNA and protein of ID1 and VEGF significantly decreased in groups E and C (all p < 0.05). There were no significant differences in the expressions of mRNA and protein of ID1 and VEGF between group Ci and control group. There was apoptosis in groups E and C, but no apoptosis was found in group Ci and control group.Conclusion: ES can inhibit the growth of gastric cancer cells through suppressing angiogenesis and promoting apoptosis of tumor cell. This study provides a new idea for the treatment of gastric cancer.