Department of Diagnostic and Interventional Radiology, Medical Faculty, University of Dusseldorf, Dusseldorf, Germany.
Br J Radiol. 2013 May;86(1025):20120570. doi: 10.1259/bjr.20120570.
To compare the effect of implanted medical materials on (18)F-fludeoxyglucose ((18)F-FDG) positron emission tomography (PET)/MRI using a Dixon-based segmentation method for MRI-based attenuation correction (MRAC), PET/CT and CT-based attenuation-corrected PET (PETCTAC).
12 patients (8 males and 4 females; age 58±11 years) with implanted medical materials prospectively underwent whole-body (18)F-FDG PET/CT and PET/MRI. CT, MRI and MRAC maps as well as PETCTAC and PETMRAC images were reviewed for the presence of artefacts. Their morphology and effect on the estimation of the (18)F-FDG uptake (no effect, underestimation, overestimation compared with non-corrected images) were compared. In PETMRAC images, a volume of interest was drawn in the area of the artefact and in a reference site (contralateral body part); the mean and maximum standardised uptake values (SUVmean; SUVmax) were measured.
Of 27 implanted materials (20 dental fillings, 3 injection ports, 3 hip prostheses and 1 sternal cerclage), 27 (100%) caused artefacts in CT, 19 (70%) in T1 weighted MRI and 17 (63%) in MRAC maps. 20 (74%) caused a visual overestimation of the (18)F-FDG uptake in PETCTAC, 2 (7%) caused an underestimation and 5 (19%) had no effect. In PETMRAC, 19 (70%) caused spherical extinctions and 8 (30%) had no effect. Mean values for SUVmean and SUVmax were significantly decreased in artefact-harbouring sites (p<0.001).
Contrary to PET attenuation correction artefacts in PET/CT, which often show an overestimation of the (18)F-FDG uptake, MRAC artefacts owing to implanted medical materials in most cases cause an underestimation.
Being aware of the morphology of artefacts owing to implanted medical materials avoids interpretation errors when reading PET/MRI.
比较基于狄克逊（Dixon）分段法的磁共振衰减校正（MRAC）、PET/CT 和 CT 衰减校正 PET（PETCTAC）对植入医用材料的（18）F-氟脱氧葡萄糖（（18）F-FDG）正电子发射断层扫描（PET）/磁共振（MRI）的影响。
12 例（8 男 4 女；年龄 58±11 岁）植入医用材料的患者前瞻性地进行全身（18）F-FDG PET/CT 和 PET/MRI 检查。评估 CT、MRI 和 MRAC 图以及 PETCTAC 和 PETMRAC 图像中是否存在伪影。比较它们的形态及其对（18）F-FDG 摄取（无影响、低估、与未校正图像相比高估）的估计的影响。在 PETMRAC 图像中，在伪影区域和参考部位（对侧身体部位）画一个感兴趣区（ROI）；测量平均和最大标准化摄取值（SUVmean；SUVmax）。
27 种植入材料（20 种牙填充物、3 种注射端口、3 种髋关节假体和 1 种胸骨环扎）中，27 种（100%）在 CT 中产生伪影，19 种（70%）在 T1 加权 MRI 中产生伪影，17 种（63%）在 MRAC 图中产生伪影。20 种（74%）在 PETCTAC 中导致（18）F-FDG 摄取的视觉高估，2 种（7%）导致低估，5 种（19%）无影响。在 PETMRAC 中，19 种（70%）导致球形衰减，8 种（30%）无影响。在含有伪影的部位，SUVmean 和 SUVmax 的平均值显著降低（p<0.001）。
与 PET/CT 中因植入医用材料导致的 PET 衰减校正伪影通常导致（18）F-FDG 摄取的高估不同，MRAC 伪影在大多数情况下导致低估。
了解因植入医用材料导致的伪影的形态可以避免在阅读 PET/MRI 时出现解释错误。
