in colorectal cancer surgery , lymph node dissection is performed by ligating and resecting the inferior mesenteric artery or the superior rectal artery ( sra ) . intravenous injection of icg was reported to be useful to decide the point of proximal colon resection . however , even after this technique , malperfusion of anastomosis was observed . if the watershed area of each major artery can be identified prior to anastomosis , it may be possible to prevent malperfusion of anastomosis . moreover , the resection of the main artery watershed area may result in complete resection of lymph nodes along the main artery and area of potential ischemia . colorectal cancer surgery was performed in a patient using fluorescence angiography to determine the watershed area of the sra . this research was approved by the international university of health and welfare research ethics committee ( approval no . 13-b-60 ) and carried out using a pinpoint ( novadaq , mississauga , on , canada ) bright - field , color , near - infrared fluorescence camera . a man in his 60  s with a chief complaint of hematochezia visited our hospital , was diagnosed with colorectal cancer and underwent laparoscopic low anterior resection with d3 dissection . after resecting the rectum on the anal side , 1  ml of 5  mg / ml indocyanine green ( icg ) was injected into the resection - side sra , which was the main artery watershed area of the tumor , as an extraperitoneal cavity procedure . observation was performed using the pinpoint , and the watershed area of the sra fluoresced 33  s after the intra - arterial injection of icg ( fig . the scope of the resection on the oral side was decided so that it included the sra watershed area , and anastomosis was performed . few reports have used the fluorescence properties of icg for intraoperative imaging diagnosis for colorectal cancer surgery . ris et al . reported performing anterior resection of the rectum and right hemicolectomy in 30 patients in whom they injected icg intravenously and used the pinpoint to observe the anastomotic site . reported that the rate of anastomotic leakage was lower when fluorescence angiography was used in colorectal cancer surgery . icg is usually used for fluorescence angiography , but kudszus et al .   observed while performing intravenous administration after or immediately before anastomosis , while jafari et al . kudszus et al .   judged the tissue blood flow to be insufficient in the planned anastomotic site in 13.9% ( 28/201 ) of their patients , and they expanded the extent of the resection . sherwinter   reported a method for evaluating the mucosal blood flow at the site of rectal anastomosis by inserting the pinpoint via the anus and injecting icg intravenously . intravenous injection of icg was reported to be useful to decide the point of proximal colon resection . intravenous injection of icg may not be perfect for deciding the point of proximal colon resection . observation of intestinal blood flow has previously been reported by icg fluorescence method using a brightfield color near - infrared fluorescence camera ( hypereye medical system ) . in this study , icg was injected into the severed main artery , and the watershed area of the artery was observed by fluorescence angiography using the pinpoint . this method differs from the previously reported method of achieving contrast via peripheral veins , since the icg is introduced via an artery on the resection - side . our literature search of pub med using  icg  and  intra - arterial injection  as keywords found no similar reports . there was concern that the boundary might be blurred in this method of fluorescence angiography via a main artery because there is communication with marginal arteries , but , in fact , the boundary of the watershed area of the main artery was clearly visualized with this method . therefore , it was possible to clearly identify the area that would be affected by treatment of the vessel , and it was expected that it would be possible to determine the optimal intestinal tract resection site for anastomosis . moreover the resection of the main artery watershed area may result in complete resection of lymph nodes along the main artery . however , this method does not evaluate the blood flow in the anal - side rectum , because it is performed after the anal - side rectum is resected by an intraperitoneal procedure . this method can be carried out merely by puncture - needle cannulation of the main artery and observation , and it is possible to easily identify the main artery watershed area . the time required for the procedure is approximately 2  min , so it can also be considered acceptable from the perspective of operative time . this is a method of evaluation before intestinal resection , and it appears to be a useful intraoperative diagnostic imaging technique for confirming the blood flow . few reports have used the fluorescence properties of icg for intraoperative imaging diagnosis for colorectal cancer surgery . ris et al . reported performing anterior resection of the rectum and right hemicolectomy in 30 patients in whom they injected icg intravenously and used the pinpoint to observe the anastomotic site . reported that the rate of anastomotic leakage was lower when fluorescence angiography was used in colorectal cancer surgery . icg is usually used for fluorescence angiography , but kudszus et al .   observed while performing intravenous administration after or immediately before anastomosis , while jafari et al . kudszus et al .   judged the tissue blood flow to be insufficient in the planned anastomotic site in 13.9% ( 28/201 ) of their patients , and they expanded the extent of the resection . sherwinter   reported a method for evaluating the mucosal blood flow at the site of rectal anastomosis by inserting the pinpoint via the anus and injecting icg intravenously . intravenous injection of icg was reported to be useful to decide the point of proximal colon resection . intravenous injection of icg may not be perfect for deciding the point of proximal colon resection . observation of intestinal blood flow has previously been reported by icg fluorescence method using a brightfield color near - infrared fluorescence camera ( hypereye medical system ) . in this study , icg was injected into the severed main artery , and the watershed area of the artery was observed by fluorescence angiography using the pinpoint . this method differs from the previously reported method of achieving contrast via peripheral veins , since the icg is introduced via an artery on the resection - side . our literature search of pub med using  icg  and  intra - arterial injection  as keywords found no similar reports . there was concern that the boundary might be blurred in this method of fluorescence angiography via a main artery because there is communication with marginal arteries , but , in fact , the boundary of the watershed area of the main artery was clearly visualized with this method . therefore , it was possible to clearly identify the area that would be affected by treatment of the vessel , and it was expected that it would be possible to determine the optimal intestinal tract resection site for anastomosis . moreover the resection of the main artery watershed area may result in complete resection of lymph nodes along the main artery . however , this method does not evaluate the blood flow in the anal - side rectum , because it is performed after the anal - side rectum is resected by an intraperitoneal procedure . this method can be carried out merely by puncture - needle cannulation of the main artery and observation , and it is possible to easily identify the main artery watershed area . the time required for the procedure is approximately 2  min , so it can also be considered acceptable from the perspective of operative time . this is a method of evaluation before intestinal resection , and it appears to be a useful intraoperative diagnostic imaging technique for confirming the blood flow . a method for performing icg fluorescence angiography of the sra watershed area during colorectal cancer surgery was reported . the method is simple and can be performed within a short time , and it enables visual evaluation of the blood flow in the intestinal tract before anastomosis . this method can be expected to provide useful information of lymph nodes along the main artery and area of potential ischemia . 13-b-60 ) by the research ethics committee at the international university of health and welfare , tochigi , japan . sr have made substantial contributions to conception and design , or acquisition of data , or analysis and interpretation of data . my have been involved in drafting the manuscript or revising it critically for important intellectual content .
highlightswe have reported the case that underwent colorectal resection with intraoperative indocyanine green ( icg ) fluorescence angiography from the resection - side of the superior rectal artery.watershed area of the sra fluoresced 33  s after the intra - arterial injection of icg.pinpoint , a brightfield color fluorescence camera was used for icg fluorescence.this method can be expected to provide useful information for maintaining the blood flow at the anastomotic site .