Detection Of Tiny Lymph Nodes Using A Near-infrared Camera With Ingaas Element
Shinsuke Akita, Nobuyuki Mitsukawa, Yuzuru Ikehara.
Chiba University, Chiba city, Japan.
Purpose: Obstruction of the lymphatic flow following LN dissection has been recognized as a therapeutic target for microsurgical reconstruction. It is not always possible to detect non-palpable small lymph nodes (LNs) surrounded by adipose tissue under the wavelength of visible light. A newly developed near-infrared camera with InGaAs element is able to capture photographs using light at >1000-nm wavelength, at which the difference in absorbance between water and lipids is large. This study investigated the ability to detect non-visible small LNs using light at 1300-nm wavelength. Methods: Following retrieval of LNs through axillary LN dissection obtained from 20 patients with breast cancer, residual specimens were simultaneously photographed using light at 970-nm, 1070-nm, 1200-nm, 1300-nm, 1450-nm, and 1600-nm wavelengths. A total of 45 specimens were observed pathologically at the selected portions in which the 1300-nm light was absorbed (high absorbance group, n = 25) and those in which the 970-nm light was absorbed instead (low absorbance group, n = 20). Results: All specimens categorized in the high absorbance group detected the LNs, whereas none of those categorized in the low absorbance group detected a LN. The sensitivity and specificity in the identification of a LN were 1.0. The LNs detected using this camera were significantly smaller than those detected by surgeons (3.00±2.93 mm vs. 5.90±3.91 mm, P< 0.01). Metastasis was observed in five of the 28 LNs detected in the second examination. In two of them metastasis was observed only in the second examination. Conclusion: The light at 1300-nm wavelength was absorbed by axillary LNs. This newly developed camera detected LNs which were undetectable by surgeons. This novel technology may be applied to lymphatic microsurgery and contribute to the development of a minimally invasive LN dissection method.
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