Original paper Optimization and evaluation of reconstruction-based compensation methods and reconstruction parameters for Tc-99m MIBI parathyroid SPECT Tawatchai Ekjeen a, * , Chiraporn Tocharoenchai a , Pawana Pusuwan b , George S.K. Fung c , Michael Ghaly c , Yong Du c , Eric C. Frey c a Department of Radiological Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand b Department of Radiology, Siriraj Hospital, Bangkok, Thailand c The Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA article info Article history: Received 2 July 2014 Received in revised form 16 December 2014 Accepted 17 December 2014 Available online xxx Keywords: Reconstruction-based compensation Reconstruction parameters Tc-99m MIBI parathyroid SPECT Monte Carlo simulation Channelized Hotelling observer abstract The value of Tc-99m MIBI parathyroid SPECT for localizing parathyroid hyperplasia in chronic renal failure patients remains inconclusive due to limited image quality. Advanced reconstruction methods to improve image quality have been developed but require optimization and evaluation. The goal of this study was to optimize and evaluate compensation methods and reconstruction parameters for Tc-99m MIBI parathyroid SPECT. A phantom population and projection data that modelled clinically realistic variations found in patients were simulated. The 3D OS-EM reconstruction with compensation for attenuation, detector response and scatter in various combinations were studied. For each compensation, the number of updates for OS-EM and the cutoff frequency of a 3D Butterworth filter were optimized and evaluated using anthropomorphic model observer. With optimal parameters, the method with compensation for attenuation and detector response, with or without the addition of scatter compen- sation, provided the highest lesion detectability for Tc-99m MIBI parathyroid SPECT. © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved. Introduction Parathyroid planar imaging with Tc-99m MIBI is widely used for the localization of hyperfunctioning parathyroid glands. The im- aging technique can be performed using dual-phase Tc-99m MIBI and dual-isotope subtraction techniques [1]. The planar imaging techniques have shown high sensitivity to detect parathyroid ad- enomas in patients with primary hyperparathyroidism [2]. On the other hand, there have been poorer results in the detection of parathyroid hyperplasia, typically found in chronic renal failure patients, with the sensitivities of 50% in a number of studies [3e5]. The reason for the inferior results in the detection of parathyroid hyperplasia is uncertain, and one of the several reasons may be the size of hyperplastic parathyroid glands, which are usually smaller in size compared to parathyroid adenomas [6]. Single photon emission computed tomography (SPECT) imaging has been increasingly used in order to improve the localization of hyperfunctioning parathyroid glands. This technique has proven useful and provides more precise location than planar imaging and allows the detection of smaller lesions [7]. However, the value of SPECT imaging for localizing parathyroid hyperplasia in chronic renal failure patient is unclear. SPECT images are degraded by several factors including photon attenuation, scatter, and collimator-detector response [8]. Compensation for these factors has the potential to improve image quality. Compensation can be achieved using advanced iterative image reconstruction algorithms that incorporate model-based compen- sation for various image-degrading factors. The quality of SPECT images obtained by these methods is impacted by reconstruction and post-reconstruction filter parameters. Selecting optimal pa- rameters is important for maximizing image quality. For these reasons, it is very important to optimize the reconstruction pa- rameters for Tc-99m MIBI parathyroid SPECT and investigate the utility of the various compensation methods. Thus the goal of this study was to optimize and evaluate the compensation methods and * Corresponding author. 2 Prannok Road, Siriraj, Bangkok-noi, Bangkok 10700, Thailand. Tel.: þ66 2 419 7173. E-mail address: tawatchai.ekj@mahidol.ac.th (T. Ekjeen). Contents lists available at ScienceDirect Physica Medica journal homepage: http://www.physicamedica.com http://dx.doi.org/10.1016/j.ejmp.2014.12.005 1120-1797/© 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved. Physica Medica xxx (2014) 1e8 Please cite this article in press as: Ekjeen T, et al., Optimization and evaluation of reconstruction-based compensation methods and reconstruction parameters for Tc-99m MIBI parathyroid SPECT, Physica Medica (2014), http://dx.doi.org/10.1016/j.ejmp.2014.12.005