FIG. 4.

Fluorescent detection of residual disease in the surgical bed after incomplete resection and BMI to track local recurrence in the surgical bed. a The mouse was imaged after surgically removing the primary tumor guided by PAI. The residual disease could not be visualized by the surgeon; however, it was clearly detected by the NIR fluorescence imaging system. After additional surgery, no residual disease was detected. The contrast of the suspicious tissue was approximately 3:1 compared with the background normal tissue. The high-power magnification and low-power magnification histological sections confirmed the tumor cells in this specimen. Scale bar 2 mm. b The invisible small residual disease was fluorescently detected by the intraoperative planar fluorescence imaging system. Although the size of the suspicious tissue was much smaller than the primary tumor in this figure, the contrast was almost the same (3:1). H&E staining confirmed the presence of residual cancer cells in the suspicious tissues. Higher magnification microscopic image of the tumor tissue section showed the residual nodule interface. Scale bar 2 mm. c BMI on the 14th, 21st, and 28th day post-operation. Overall, 8.7 and 33.3 % of the mice in the targeted and control animal groups, respectively, had local recurrence, and approximately 30 % of the mice in both groups had lymph node metastasis. In the control group, most recurrent tumors grew larger than 1 cm within 3 weeks post-operation. BMI bioluminescence imaging, PAI photoacoustic imaging, NIR near-infrared, H&E hematoxylin and eosin