TY - JOUR T1 - <strong>Absolute quantification provided by <sup>177</sup>Lu SPECT images recorded by a high-speed 360° whole-body CZT camera: a feasibility study on phantom and patient</strong> JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1304 LP - 1304 VL - 61 IS - supplement 1 AU - Laetitia Imbert AU - Elodie Chevalier AU - Marine Claudin AU - Gilles Karcher AU - Pierre-Yves Marie Y1 - 2020/05/01 UR - http://jnm.snmjournals.org/content/61/supplement_1/1304.abstract N2 - 1304Introduction: 177Lu radionuclide therapy is increasingly used in clinical routine but remains difficult to monitor, due to the difficulty in obtaining absolute quantification and dosimetry estimations with current gamma-camera systems. However, major technical progress has been achieved in recent years for CZT-SPECT imaging systems. The Veriton® camera (Spectrum Dynamics Medical) is a high-speed whole-body 360° CZT-camera equipped with 12 swiveling high-resolution detectors, which can be positioned in close proximity to patients, thereby providing a high count-sensitivity that is particularly advantageous for the current low-count rate conditions of 177Lu imaging. The aim of this study was to evaluate the feasibility of absolute quantification of 177Lu SPECT from phantom and patient images using this new CZT camera. Methods: SPECT and CT images were obtained from both: (i) an IEC body phantom filled-in with 177Lu solutions and with a ratio of 1:8 between hot spheres and background, and (ii) a 70 y/o woman, who received 4 Lutathera injections at consecutive 2-month intervals. For the latter, whole-body acquisitions of less than 20 minutes (6 bed positions of 3 mins each) were recorded 24 hours after each Lutathera injection. All SPECT images were recorded on the 113 keV (±10%) energy peak and reconstructed with implementation of CT-based attenuation correction, scatter correction and resolution recovery. Results: A high signal-noise ratio was obtained from the phantom images, as well as a reliable determination of activity concentrations with an average relative error of 0.5% for background activity and 6% for the activities of spheres of 17 to 37 mm diameters. On the patient’s whole-body SPECT images obtained the day after each of the 4 Lutathera injections, subclavian nodes, hepatic and bone lesions could be easily detected (see the MIP images in the upper half of Figure 1), and their absolute quantifications gave evidence of a global and gradual decrease in tracer uptake between the 4 injections (see the curves in the lower half of Figure 1). Conclusions: This study demonstrates the high potential of a high-speed whole-body 360° CZT-camera for the monitoring of 177Lu radionuclide therapy in clinical routine, with a sufficiently precise absolute quantification of 177Lu and a short enough 3D whole-body recording time. ER -