title: Computer-aided detection scheme for sentinel lymph nodes in lymphoscintigrams using symmetrical property around mapped injection point.
abstract: It is difficult to detect sentinel lymph nodes (SLNs) around an injection point of radiopharmaceuticals mapped in lymphoscintigrams. The purpose of this study was to develop a computer-aided detection (CAD) scheme for SLNs by a subtraction technique using the symmetrical property in the mapped injection point. Our database consisted of 78 lymphoscintigrams with 86 SLNs. In our CAD scheme, the mapped injection point of radiopharmaceuticals was first segmented from the lymphoscintigram using a gray-level thresholding technique. Lymphoscintigram was then divided into four regions by vertical and horizontal straight lines through the center of the segmented injection point. One of the four divided regions was defined as the target region. The correlation coefficients based on pixel values were calculated between the target region and each of the other three regions. The region with the highest correlation coefficient among three regions was selected as the similar region to the target region. The values of pixels on the target region were subtracted by the values of the corresponding pixels on the similar region. This procedure was repeated until every divided region had been used as target region. SLNs were segmented by applying a gray-level thresholding technique to the subtracted image. With our CAD scheme, sensitivity and the number of false positives were 95.3% (82/86) and 2.51 per image, respectively. Our CAD scheme achieved a high level of detection accuracy, and would have a great potential in assisting physicians to detect SLNs in lymphoscintigrams.
authors: Department of Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, 514-8507, Mie, Japan. nakayama@clin.medic.mie-u.ac.jp
authors: Ryohei
authors: R
authors: Nakayama
authors: Akiyoshi
authors: A
authors: Hizukuri
authors: Koji
authors: K
authors: Yamamoto
authors: Nobuo
authors: N
authors: Nakako
authors: Naoki
authors: N
authors: Nagasawa
authors: Kan
authors: K
authors: Takeda
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology; D016208:Databases, Factual; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology; D061305:Lymphoscintigraphy / Q000379:methods*; D010363:Pattern Recognition, Automated; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012680:Sensitivity and Specificity; D021701:Sentinel Lymph Node Biopsy; D013382:Subtraction Technique