188Re image performance assessment using small animal multi-pinhole SPECT/PET/CT system. (January 2017)

• Record Type: Journal Article
• Authors: Esquinas, Pedro L.; Rodríguez-Rodríguez, Cristina; Carlos De La Vega, José; Bokharaei, Mehrdad; Saatchi, Katayoun; Shirmohammad, Maryam; Häfeli, Urs O.; Sossi, Vesna; Celler, Anna
• Is Part Of: Physica medica. Volume 33(2017)
• Page Start: 26
• Page End: 37
• Publication Date: 2017-01
• Subjects: 188Re -- Small-animal SPECT -- Image quality -- Image quantification; Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2016.11.105
• Languages: English
• ISSNs: 1120-1797

Abstract

Highlights: The performance of a pre-clinical SPECT/CT system for 188 Re imaging is investigated. Image quality and image quantification is assessed for two multi-pinhole collimators. Monte-Carlo simulations of the pre-clinical SPECT system were performed. Image quality and image quantification of 188 Re was comparable to 99m Tc performance. 188 Re images suffered from higher noise due to large number of down-scatter photons. Abstract: Purpose: The goal of this study was to investigate the performance of a pre-clinical SPECT/PET/CT system for 188 Re imaging. Methods: Phantom experiments were performed aiming to assess the characteristics of two multi-pinhole collimators: ultra-high resolution collimator (UHRC) and high-energy ultra high resolution collimator (HE-URHC) for imaging 188 Re. The spatial resolution, image contrast and contrast-to-noise ratio (CNR) were investigated using micro- Jaszczak phantoms. Additionally, the quantification accuracy of 188 Re images was evaluated using two custom-designed phantoms. The 188 Re images were compared to those obtained with 99m Tc (gold standard); the acquired energy spectra were analyzed and Monte-Carlo simulations of the UHRC were performed. To verify our findings, a C57BL / 6 -mouse was injected with 188 Re-microspheres and scanned with both collimators. Results: The spatial resolution achieved in 188 Re images was comparable to that of 99m Tc. Acquisitions using HE-UHRC yielded 188 Re images with higher contrast and CNR than UHRC. Studies of quantitative accuracy of 188 Re images resulted in <10% errors for both collimators when the activity was calculated within a small VOI around the object of interest. Similar quantification accuracy was achieved for 99m Tc. However, 188 Re images showed much higher levels of noise in the background. Monte-Carlo simulations showed that 188 Re imaging with UHRC is severely affected by down-scattered photons from high-energy emissions. The mouse images showed similar biodistribution of 188 Re-microspheres for both collimators. Conclusions: VECTor/CT provided 188 Re images quantitatively accurate and with quality comparable to 99m Tc. However, due to large penetration of UHRC by high-energy photons, the use of the HE-UHRC for imaging 188 Re in VECTor/CT is recommended.