research article Efficacy of high-energy collimator for sentinel node lymphoscintigraphy of early breast cancer patients Kamran Aryana1, Mohaddeseh Gholizadeh1, Mehdi Momennezhad1, Maryam Naji1, Mohsen Aliakbarian2, Mohammad Naser Forghani3, Ramin Sadeghi1 1 Nuclear Medicine Research Center, Faculty of Medicine, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran 2 Surgical Oncology Research Center, Faculty of Medicine, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran 3 Cancer Research Center, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Radiol Oncol 2012; 46(1): 75-80. Received 22 October 2011 Accepted 8 December 2011 Correspondence to: Assistant Professor Ramin Sadeghi, Nuclear Medicine Research Center, Imam Reza Hospital, Mashhad University of Medical Sciences, Ebn Sina Street. Mashhad, Iran. E-mail: sadeghir@mums.ac.ir Disclosure: No potential conflicts of interest were disclosed. Introduction. Lymphoscintigraphy is an important part of sentinel node mapping in breast cancer patients. Sometimes star shaped artefacts due to septal penetration can be problematic during imaging. In the current study, we evaluated the possibility of high energy (HE) collimators use for lymphoscintigraphy. Patients and methods. Twenty patients with early breast carcinoma were included. Thirty minutes after radiotracer injection (99mTc-antimony sulphide colloid), anterior and lateral images were acquired using a dual head gamma camera equipped with a parallel hole low energy high resolution (LEHR) collimator on one head and HE collimator on another head. All images were reviewed by two nuclear medicine specialists regarding detectability and number of axillary sentinel nodes and presence of star artefact. Results. All images taken by LEHR collimators showed star artefact of the injection site. No image taken by HE colli- mator showed this effect. In two patients the sentinel node was visible only by HE collimator. Tumour location in both of these patients was in the upper lateral quadrant and both had history of excisional biopsy. In two patients additional sentinel node was visible adjacent to the first one only on the LEHR images. Conclusions. HE collimators can be used for sentinel lymph node mapping and lymphoscintigraphy of the breast cancer patients. This collimator can almost eliminate star-shaped artefacts due to septal penetration which can be advantageous in some cases. However, to separate two adjacent sentinel nodes from each other LEHR collimators perform better. Key words: sentinel node; lymphoscintigraphy; collimator; HEAP; high energy all purpose; low energy high resolution; LEHR Introduction Sentinel node biopsy is the standard method of ax- illary staging in early breast cancer patients.1 During surgery the sentinel nodes can be detect- ed with two different techniques; alone or in com- bination: radiotracer and/or blue dye approaches.2 Imaging after radiotracer injection (lymphoscin- itgraphy) was recommended by most guidelines which can help in performing sentinel node biopsy flawlessly.3 Usually after injection of the radiotrac- er in the breast (in a specific location according to the used protocol), lymphoscintigraphy was per- formed in different time intervals.4 A major prob- lem while imaging the axilla, was concealment of the sentinel nodes by the activity in the injection Radiol Oncol 2012; 46(1): 75-80. doi:10.2478/v10019-012-0013-3 75