CT Based Lymphatic Mapping And Localization Of Sentinel Lymph Node For Breast Cancer Patients

Objective:To evaluate the feasibility of Sentinel Lymph Node(SLN) mapping with CT lymphography(CT-LG),and then directing of sentinel lymph node biopsy(SLNB)in early-stage breast cancer patients.The objective of the present study is to explore the clinical value of CT based lymphatic mapping and localization. A comparison would be made between CT-based lymphatic mapping with the traditional method(isotope and/or blue dye) for localization of SLN in breast cancer patients.Methods:A total of 25 breast cancer patients underwent CT scan to locate SLN before SLNB at the same day of surgery.The Breast Lesion Localization Needles (interv.)was used to identify SLN after three-dimensional computed tomography lymphograph with iopamidol guided by InSpace software navigation system (only in 21 patients).The needle would stay in the patient's axilla until the surgery. All the lymph nodes including the CT defined and which marked by methylene blue dye or 99mTc-sulfur colloid tracers were removed,which then would be tested by touch imprint cytology for the intraoperative diagnosis.Patients with node involved would receive axillary dissection.And then comparing with SLNB, if the number of SNs in CT was equal,the evaluation was coherence, more or less were respective high and low evaluation.The quality of imaging were classedⅠandⅡby lymph duct appearance or not on the image which were reconstructed by volume.Obesity was defined when the value of body mass index(BMI) was more 25.The results were assessed using Fisher exact test.Results:Part one:A total of 51 SLNs were identified in these 21 patients, with a medium number of 2 SLNs for each patient(range 1-4).The successful rate, sensitivity, specificity and concordance index to the traditional way of the novel method were 85.7%(18/21 cases),83%(5/6 cases),86.7% (13/15 cases),85.7%(18/21 cases),respectively.None of these 21 patients showed any adverse events during or after CT examination and surgery. With the assistant of CT location, the mean time of SLNB had been shortened from 20 mins to 16 mins.Part two:(1)Of 25 patients,5 patients which had local mastectomy were included.The patients with BMI<25 were 20 cases, and≥25 were 5 cases. (2)All the CT-LG showed SLN, and 84.0%(n=21)cases mapping quality were class 1,16.7%(n=4) were classⅡ.The obese patients were difficult to acquire high quality mapping, and the difference was significant (P< 0.05).(3)Fifty-six SLN and 45 lymph duct in all of 25 patients were identified on CT-LG mapping.Comparing with the results of SLNB,36.0%(n=9) patients CT-LG mapping were equal evaluation,28.0%(n=7) and 36.0%(n=9) patients had high and low evaluation, respectively. The BMI and surgical history were the main reasons,which had significant differences(P<0.05). (4)Eighteen patients with 52 SLNs were negative,and 7 patients with 15 SLNs were positive confirmed by pathology, but on CT-LG mapping,43 negative and 13 positive SLNs were acquired.The 32.6%(14/43)negative SLN and 76.9%(10/13)positive SLN were round shape,the difference was significant (P<0.05).The 9.3%(4/43) negative SLNs and 23.1%(3/13) positive SLNs demonstrated filling defect on the center, but irregular filling defect on the margin were found only in 30.8%(4/13) of positive SLNs.However,3 SLNs(2 patients)combined with multi-small lymph nodes on CT-LG mapping were also confirmed tumor cell invasive by pathology.Conclusion:CT guided axillary SLN mapping and localization showed excellent specificity and gave concordant results in locating sentinel lymph nodes. These results suggest that CT guided localization would be a valuable tool for identifying sentinel lymph nodes in breast cancer patients.CT-LG can sufficiently visualize breast lymphatic drainage and may have potential utility for breast SLN mapping, but can be influenced by the obese patients and the surgical history of tumor affected breast.On CT-LG mapping, SLN that showed round shape,filling defect on the margin, and combined with multi-small lymph nodes around, were likely to metastatic SLN.