New digital detectors and block-sequential regularized expectation maximization (BSREM) reconstruction algorithm improve positron emission tomography (PET)/magnetic resonance (MR) image quality. The impact on image quality may differ from analogue PET/computed tomography (CT) protocol. The aim of this study is to determine the potential reduction of injected [68Ga]Ga-DOTA-TATE activity for digital PET/MR with BSREM reconstruction while maintaining at least equal image quality compared to the current analogue PET/CT protocol. NEMA IQ phantom data and 25 patients scheduled for a diagnostic PET/MR were included. According to our current protocol, 1.5 MBq [68Ga]Ga-DOTA-TATE per kilogram (kg) was injected. After 60 min, scans were acquired with 3 (≤ 70 kg) or 4 (> 70 kg) minutes per bedposition. PET/MR scans were reconstructed using BSREM and factors β 150, 300, 450 and 600. List mode data with reduced counts were reconstructed to simulate scans with 17%, 33%, 50% and 67% activity reduction. Image quality was measured quantitatively for PET/CT and PET/MR phantom and patient data. Experienced nuclear medicine physicians performed visual image quality scoring and lesion counting in the PET/MR patient data. Phantom analysis resulted in a possible injected activity reduction of 50% with factor β = 600. Quantitative analysis of patient images revealed a possible injected activity reduction of 67% with factor β = 600. Both with equal or improved image quality as compared to PET/CT. However, based on visual scoring a maximum activity reduction of 33% with factor β = 450 was acceptable, which was further limited by lesion detectability analysis to an injected activity reduction of 17% with factor β = 450. A digital [68Ga]Ga-DOTA-TATE PET/MR together with BSREM using factor β = 450 result in 17% injected activity reduction with quantitative values at least similar to analogue PET/CT, without compromising on PET/MR visual image quality and lesion detectability.

中文翻译：

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与模拟 PET/CT 相比，数字 PET/MR 的 [68Ga]Ga-DOTA-TATE 注射活性降低


新的数字探测器和块顺序正则化期望最大化 (BSREM) 重建算法提高了正电子发射断层扫描 (PET)/磁共振 (MR) 图像质量。对图像质量的影响可能与模拟 PET/计算机断层扫描 (CT) 协议不同。本研究的目的是确定采用 BSREM 重建的数字 PET/MR 注射 [68Ga]Ga-DOTA-TATE 活性的潜在减少，同时与当前的模拟 PET/CT 协议相比至少保持相同的图像质量。其中包括 NEMA IQ 体模数据和 25 名计划进行诊断性 PET/MR 的患者。根据我们目前的方案，每公斤（kg）注入1.5 MBq [68Ga]Ga-DOTA-TATE。 60 分钟后，每次卧位 3 分钟（≤ 70 kg）或 4 分钟（> 70 kg）进行扫描。使用 BSREM 和因子 β 150、300、450 和 600 重建 PET/MR 扫描。重建计数减少的列表模式数据以模拟活动减少 17%、33%、50% 和 67% 的扫描。定量测量 PET/CT 和 PET/MR 体模和患者数据的图像质量。经验丰富的核医学医师对 PET/MR 患者数据进行视觉图像质量评分和病灶计数。体模分析导致注射活动可能减少 50%（因子 β = 600）。对患者图像的定量分析显示，注射活动可能减少 67%（因子 β = 600）。与 PET/ 相比，两者的图像质量相同或有所改善。 CT。然而，根据视觉评分，因子 β = 450 时最大活性降低 33% 是可以接受的，这进一步受到病变可检测性分析的限制，因子 β = 450 时注射活性降低 17%。 使用因子 β = 450 的数字 [68Ga]Ga-DOTA-TATE PET/MR 与 BSREM 一起导致注射活性降低 17%，其定量值至少与模拟 PET/CT 相似，而不会影响 PET/MR 视觉图像质量和病变的可检测性。