Paul A K, Tatsumi M, Yutani K, Fujino K, Hashikawa K, Nishimura T
Division of Tracer Kinetics, Osaka University Graduate School of Medicine, Osaka University Hospital, Suita, Osaka, Japan.
Nucl Med Commun. 2002 Jan;23(1):103-10. doi: 10.1097/00006231-200201000-00016.
To investigate the effects of iterative reconstruction in 18F-fluorodeoxyglucose (FDG) gamma camera coincidence imaging (GCI), image contrast and visual detection obtained by using the iterative ordered-subsets expectation maximization (OSEM) reconstruction, in a phantom and in patients with lung cancer and breast cancer, were compared with those obtained by using the conventional filtered backprojection (FBP) reconstruction. Images of a cylindrical phantom containing hot spheres of various sizes (10-38 mm) were acquired by positron emission tomography (PET) and GCI at various sphere-to-background activity ratios. Forty-one consecutive patients with biopsy-proven cancer of lung (n = 20) and breast (n = 21) underwent PET and GCI on the same day after intravenous injection of 370 MBq of FDG. GCI images reconstructed by the OSEM and the FBP were compared. FDG PET was considered as the standard of reference. In GCI phantom images, OSEM yielded better contrast and signal-to-noise ratio (SNR) than FBP over the range of sphere sizes. Attenuation correction improved both the image measures and sphere detection obtained by the OSEM in GCI. In the study involving patients, FDG PET depicted 41 primary tumours and 25 metastatic lymph nodes. All of the tumours >2 cm in diameter (n = 25), six of the nine tumours 1.5-2.0 cm in diameter (67%), two of seven tumours <1.5 cm in diameter (29%), and 20 metastatic lymph nodes (80%) were detected in attenuation uncorrected GCI reconstructed by the OSEM as well as the FBP. The undetected lesions in GCI were identical between the OSEM and the FBP reconstructions. OSEM yielded significantly greater tumour-to-background (T/B) ratios and lower noise than FBP in GCI (T/B ratios, 4.1+/-3.2 vs 3.7+/-2.7, P = 0.02; noise, 0.09+/-0.04 vs 0.14+/-0.05, P<0.0001). In conclusion, OSEM yielded better image contrast and less noise than the FBP in GCI, but the lesion detection obtained by the OSEM and the FBP in attenuation uncorrected GCI in patients with lung cancer and breast cancer were similar. Phantom data suggest the potential of OSEM for improving lesion detection in GCI after attenuation correction.
为研究迭代重建在18F-氟脱氧葡萄糖（FDG）γ相机符合成像（GCI）中的效果，将使用迭代有序子集期望最大化（OSEM）重建在模型以及肺癌和乳腺癌患者中获得的图像对比度和视觉检测结果，与使用传统滤波反投影（FBP）重建获得的结果进行比较。通过正电子发射断层扫描（PET）和GCI在不同的球与背景活度比下采集包含各种尺寸（10 - 38毫米）热球的圆柱形模型的图像。41例经活检证实为肺癌（n = 20）和乳腺癌（n = 21）的连续患者在静脉注射370 MBq的FDG后于同一天接受PET和GCI检查。比较了经OSEM和FBP重建的GCI图像。将FDG PET视为参考标准。在GCI模型图像中，在整个球尺寸范围内，OSEM产生的对比度和信噪比（SNR）均优于FBP。衰减校正改善了GCI中由OSEM获得的图像指标和球检测结果。在涉及患者的研究中，FDG PET显示了41个原发性肿瘤和25个转移性淋巴结。在经OSEM以及FBP重建的未进行衰减校正的GCI中，检测到了所有直径>2厘米的肿瘤（n = 25）、9个直径1.5 - 2.0厘米肿瘤中的6个（67%）、7个直径<1.5厘米肿瘤中的2个（29%）以及20个转移性淋巴结（80%）。GCI中未检测到的病变在OSEM和FBP重建之间是相同的。在GCI中，OSEM产生的肿瘤与背景（T/B）比值显著高于FBP，且噪声更低（T/B比值，4.1±3.2对3.7±2.7，P = 0.02；噪声，0.09±0.04对0.14±0.05，P<0.0001）。总之，在GCI中，OSEM产生的图像对比度优于FBP，噪声更低，但在肺癌和乳腺癌患者未进行衰减校正的GCI中，OSEM和FBP获得的病变检测结果相似。模型数据表明OSEM在衰减校正后改善GCI中病变检测的潜力。
