In recent years, different metal artifact reduction methods have been developed for CT. These methods have only recently been introduced for PET/CT even though they could be beneficial for interpretation, segmentation, and quantification of the PET/CT images. In this study, phantom and patient scans were analyzed visually and quantitatively to measure the effect on PET images of iterative metal artifact reduction (iMAR) of CT data. Methods: The phantom consisted of 2 types of hip prostheses in a solution of ¹⁸F-FDG and water. ¹⁸F-FDG PET/CT scans of 14 patients with metal implants (either dental implants, hip prostheses, shoulder prostheses, or pedicle screws) and ⁶⁸Ga-labeled prostate-specific membrane antigen (⁶⁸Ga-PSMA) PET/CT scans of 7 patients with hip prostheses were scored by 2 experienced nuclear medicine physicians to analyze clinical relevance. For all patients, a lesion was located in the field of view of the metal implant. Phantom and patients were scanned in a PET/CT scanner. The standard low-dose CT scans were processed with the iMAR algorithm. The PET data were reconstructed using attenuation correction provided by both standard CT and iMAR-processed CT. Results: For the phantom scans, cold artifacts were visible on the PET image. There was a 30% deficit in ¹⁸F-FDG concentration, which was restored by iMAR processing, indicating that metal artifacts on CT images induce quantification errors in PET data. The iMAR algorithm was useful for most patients. When iMAR was used, the confidence in interpretation increased or stayed the same, with an average improvement of 28% ± 20% (scored on a scale of 0%–100% confidence). The SUV increase or decrease depended on the type of metal artifact. The mean difference in absolute values of SUV_mean of the lesions was 3.5% ± 3.3%. Conclusion: The iMAR algorithm increases the confidence of the interpretation of the PET/CT scan and influences the SUV. The added value of iMAR depends on the indication for the PET/CT scan, location and size/type of the prosthesis, and location and extent of the disease.

近年来，已经开发出用于CT的不同的金属伪影减少方法。这些方法直到最近才被引入到PET / CT中，尽管它们对PET / CT图像的解释，分割和量化可能是有益的。在这项研究中，对体模和患者扫描进行了视觉和定量分析，以测量CT数据的迭代金属伪影减少（iMAR）对PET图像的影响。方法：体模由两种类型的髋关节假体组成，分别为¹⁸ F-FDG和水。用金属植入物（牙科植入物，髋关节假体，肩关节假体或椎弓根螺钉）和⁶⁸ Ga标记的前列腺特异性膜抗原对18例患者进行^18次F-FDG PET / CT扫描（⁶⁸由2位经验丰富的核医学医师对7例髋关节假体患者的Ga / PSMA）PET / CT扫描评分，以分析其临床相关性。对于所有患者，病变均位于金属植入物的视野内。在PET / CT扫描仪中对幻影和患者进行了扫描。使用iMAR算法处理标准的低剂量CT扫描。使用标准CT和iMAR处理过的CT提供的衰减校正来重建PET数据。结果：对于幻像扫描，在PET图像上可见冷的伪影。^18岁时出现30％的赤字F-FDG浓度通过iMAR处理得以恢复，表明CT图像上的金属伪影会诱发PET数据中的定量误差。iMAR算法对大多数患者有用。当使用iMAR时，对解释的置信度增加或保持不变，平均提高28％±20％（以0％–100％的置信度评分）。SUV的增加或减少取决于金属伪影的类型。病变的SUV_平均值绝对值的_平均差为3.5％±3.3％。结论： iMAR算法提高了PET / CT扫描解释的可信度，并影响了SUV。iMAR的附加价值取决于PET / CT扫描的适应症，假体的位置和大小/类型以及疾病的位置和程度。