Objective To compare the accuracy and feasibility between methylene blue(MB)and nano-carbon(NC)in tracing sentinel lymph nodes(SLN)of clinical lymph node negative(CN0)papillary thyroid cancer(PTC). Methods Eightynine patients with CN0 papillary thyroid cancer were divided into two groups in random:MB group(n=45)and NC group(n=44).A corresponding dose of tracer was injected into tumor surrounding tissue at surgery,the SLNs were removed and sent for frozen section,the results were compared with post-operative...