title: Photo-guided sentinel node mapping in breast cancer using marker-free photo-gamma fusion lymphoscintigraphy.
abstract: OBJECTIVE
  Photo-gamma fusion lymphoscintigraphy (PGFLS) was developed by overlying a conventional planar gamma image on a photograph for the guidance of sentinel node biopsy. The feasibility and accuracy of PGFLS was assessed in breast cancer patients.
  
  
  METHODS
  A digital camera and a gamma camera were coordinated to obtain photograph and gamma images from the same angle. Using the distance to the object and calibration acquisition with a flat phantom and radioactive markers, PGFLS was performed both in phantom and in patients without fiducial markers. Marker-free PGFLS was verified using flat phantom, anthropomorphic phantom with markers simulating sentinel nodes and breast cancer patients. In addition, the depth of the radioactive marker or sentinel node was calculated using two gamma images taken at right angles. The feasibility and accuracy of PGFLS were assessed in terms of mismatch errors of co-registration and depth with reference to the data from SPECT/CT.
  
  
  RESULTS
  The mismatch error was less than 6 mm in the flat phantom image at a distance from 50 to 62 cm without misalignment. In the anthropomorphic phantom study, co-registration error was 0.42 ± 0.29 cm; depth error was 0.51 ± 0.37 cm, which was well correlated with the reference value on SPECT/CT (x scale: R(2) = 0.99, p < 0.01; y scale: R(2) = 0.99, p < 0.01; depth: R(2) = 0.99, p < 0.01). In ten patients with breast cancer referred for lympho-SPECT/CT, PGFSL enabled photo-guided sentinel lymph node mapping with acceptable accuracy (co-registration error, 0.47 ± 0.24 cm; depth error, 1.20 ±0.41 cm). The results from PGFSL showed close correlation with those from SPECT/CT (x scale: R(2) = 0.99, p < 0.01; y scale: R(2) = 0.98, p < 0.01; depth: R(2) = 0.77, p < 0.01).
  
  
  CONCLUSIONS
  The novel and convenient PGFLS technique is clinically feasible, showing acceptable accuracy and providing additional visual and quantitative information for sentinel lymph node mapping. This approach will facilitate photo-guided sentinel lymph node dissection in breast cancer.
authors.affiliation: Department of Nuclear Medicine, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do Korea 410-769.
authors.forename: Eun Seong
authors.initials: ES
authors.lastname: Lee
authors.affiliation: Department of Nuclear Medicine, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do Korea 410-769.
authors.forename: In Kook
authors.initials: IK
authors.lastname: Chun
authors.affiliation: Department of Nuclear Medicine, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do Korea 410-769.
authors.forename: Seunggyun
authors.initials: S
authors.lastname: Ha
authors.affiliation: Department of Nuclear Medicine, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do Korea 410-769.
authors.forename: Hai-Jeon
authors.initials: HJ
authors.lastname: Yoon
authors.affiliation: Center for Breast Cancer, National Cancer Center, Goyang, Republic of Korea.
authors.forename: So-Youn
authors.initials: SY
authors.lastname: Jung
authors.affiliation: Center for Breast Cancer, National Cancer Center, Goyang, Republic of Korea.
authors.forename: Seeyoun
authors.initials: S
authors.lastname: Lee
authors.affiliation: Center for Breast Cancer, National Cancer Center, Goyang, Republic of Korea.
authors.forename: Seok Won
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Center for Breast Cancer, National Cancer Center, Goyang, Republic of Korea.
authors.forename: Eun Sook
authors.initials: ES
authors.lastname: Lee
authors.affiliation: Department of Medical Engineering, National Cancer Center, Goyang, Republic of Korea.
authors.forename: Taeyoon
authors.initials: T
authors.lastname: Kim
authors.affiliation: Department of Medical Engineering, National Cancer Center, Goyang, Republic of Korea.
authors.forename: Kwang Gi
authors.initials: KG
authors.lastname: Kim
authors.affiliation: Medical Photonics Research Center, Korea Photonics Technology Institute, Gwangju, Republic of Korea.
authors.forename: Byung Il
authors.initials: BI
authors.lastname: Lee
authors.affiliation: Department of Nuclear Medicine, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do Korea 410-769.
authors.forename: Tae Sung
authors.initials: TS
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do Korea 410-769 ; Center for Breast Cancer, National Cancer Center, Goyang, Republic of Korea.
authors.forename: Seok-Ki
authors.initials: SK
authors.lastname: Kim
keywords: Photo-gamma fusion lymphoscintigraphy; Sentinel lymph node