van der Vos Charlotte S, Arens Anne I J, Hamill James J, Hofmann Christian, Panin Vladimir Y, Meeuwis Antoi P W, Visser Eric P, de Geus-Oei Lioe-Fee
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
University of Twente, Enschede, The Netherlands.
J Nucl Med. 2017 Nov;58(11):1867-1872. doi: 10.2967/jnumed.117.191171. Epub 2017 May 10.
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. The phantom consisted of 2 types of hip prostheses in a solution of F-FDG and water. F-FDG PET/CT scans of 14 patients with metal implants (either dental implants, hip prostheses, shoulder prostheses, or pedicle screws) and Ga-labeled prostate-specific membrane antigen (Ga-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. For the phantom scans, cold artifacts were visible on the PET image. There was a 30% deficit in F-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 of the lesions was 3.5% ± 3.3%. 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,已开发出不同的用于CT的金属伪影减少方法。尽管这些方法对PET/CT图像的解读、分割和定量分析可能有益,但直到最近才被引入PET/CT。在本研究中,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。体模由置于F-FDG和水溶液中的两种类型的髋关节假体组成。14例有金属植入物(牙种植体、髋关节假体、肩关节假体或椎弓根螺钉)患者的F-FDG PET/CT扫描以及7例有髋关节假体患者的Ga标记前列腺特异性膜抗原(Ga-PSMA)PET/CT扫描由2名经验丰富的核医学医师评分,以分析临床相关性。所有患者的视野内均有一个病变。体模和患者在PET/CT扫描仪中进行扫描。标准低剂量CT扫描采用iMAR算法进行处理。PET数据使用标准CT和iMAR处理后的CT提供的衰减校正进行重建。对于体模扫描,PET图像上可见冷伪影。F-FDG浓度有30%的偏差,通过iMAR处理得以恢复,这表明CT图像上的金属伪影导致PET数据出现定量误差。iMAR算法对大多数患者有用。使用iMAR时,解读的可信度增加或保持不变,平均提高28%±20%(按0%-100%可信度评分)。SUV的增加或减少取决于金属伪影的类型。病变SUV绝对值的平均差异为3.5%±3.3%。iMAR算法提高了PET/CT扫描解读的可信度并影响SUV。iMAR的附加价值取决于PET/CT扫描的适应证、假体的位置和大小/类型以及疾病的位置和范围。