Coincidence imaging using 2 dual-head gamma-camera systems, with and without attenuation correction

• Published in: Journal of nuclear medicine technology Vol. 32; no. 4; pp. 190 - 197
• Main Authors: Even-Sapir, Einat, Yuzefovich, Bella, Miller, Elka, Bouhnik, Jean-Paul, Zak, Osnat, Lerman, Hedva, Lievshitz, Genady, Levin, Charles
• Format: Journal Article
• Language: English
• Published: United States 01.12.2004
• Subjects: Adult; Aged; Breast Neoplasms - diagnosis; Female; Fluorodeoxyglucose F18; Gamma Cameras; Gastrointestinal Neoplasms - diagnosis; Humans; Image Enhancement - methods; Lung Neoplasms - diagnosis; Lymphoma, Non-Hodgkin - diagnosis; Male; Melanoma - diagnosis; Middle Aged; Ovarian Neoplasms - diagnosis; Radiopharmaceuticals; Tomography, Emission-Computed - methods
• ISSN: 0091-4916

Coincidence imaging enhances the potential for imaging a greater number of patients with 18F-FDG in centers that do not have dedicated PET systems. The purpose of this study was to compare, in a clinical setting, coincidence imaging for tumor detection using 2 dual-head gamma-camera systems, one equipped with a 5/8-in. (16 mm) detector (CoDe5) and the other equipped with a newly designed 1-in. (25.4 mm) detector (CoDe8) with an x-ray tube installed in its gantry. Thirty consecutive patients were studied by both systems during the same visit and had 4 image sets for comparison: CoDe5 without attenuation correction (CoDe5NC), CoDe8 with (CoDe8AC) and without (CoDe8NC) attenuation correction, and fused coincidence-CT images. The target-to-background ratio (T/Bg ratio) and target-to-nontarget ratio (T/NT ratio) were calculated for each tumor site. On visual assessment, 61 tumor sites were detected on CoDe8AC images. Of these, 59 (97%) were detected on CoDe8NC and 54 (88%) were detected on CoDe5NC images. Fused images improved image interpretation in 10 patients (33%) compared with coincidence images alone. Data added by fusion were of clinical relevance in 6 patients (20%). On quantitative assessment, the number of accepted events by the CoDe8 was significantly higher than that by CoDe5 (5.21 +/- 1.46 million vs. 1.27 +/- 0.36 million, P <0.001). When comparing CoDe5 with CoDe8 images without attenuation correction, the T/Bg and T/NT ratios were significantly higher on the CoDe8 images (P <0.0005 and P <0.0005, respectively). When comparing CoDe8 images with and without attenuation correction, the T/Bg ratio was better on the attenuation-corrected images (P <0.0005). Coincidence imaging with 1-in. detectors and attenuation correction improve image quality and, to a lesser extent, the tumor detection rate compared with the 5/8-in. detectors and noncorrected images. The data added by fusion of coincidence images to CT findings were clinically relevant in 20% of the patients.