Donati O F, Reiner C S, Hany T F, Fornaro J, von Schulthess G K, Marincek B, Weishaupt D
Institute of Diagnostic Radiology, University Hospital Zürich, 8091 Zürich, Switzerland.
Nuklearmedizin. 2010;49(3):106-14. doi: 10.3413/nukmed-0263. Epub 2010 Apr 20.
To evaluate the accuracy of retrospective rigid image registration and fusion between F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) of the upper abdomen.
PATIENTS, MATERIAL, METHODS: Image fusion of PET and MRI was performed in 30 patients with suspected malignancy of the liver or pancreas. Using a commercially available image fusion tool capable of rigid manual point-based registration, PET-Images were retrospectively registered and fused by matching eight homologous points in the 3D spoiled gradient echo (GRE) MRI sequences acquired in portal venous phase and in the CT-component of PET/CT. Two separate observers (R1, R2) assessed accuracy of image registration by determining the distances in the x-, y- and z-axis as well as the absolute distance between anatomical landmarks which differed from the landmarks chosen for registration. Quality of fusion was graded using a three point grading scale (1 poorly fused; 2 satisfactory fused; 3 correctly fused) and compared to hybrid PET/CT fusion.
Mean time of registration per patient was less than 2 minutes. Objective registration assessment showed errors between 2.4-6.3 mm in x-axis: mean 3.6 mm (R1); 4.6 mm (R2), 2.3-9.3 mm in y-axis (mean 5.1 mm; 5.5 mm) and 3.3-12.0 mm in z-axis (mean 5.9 mm; 5.9 mm.) The mean error in absolute distance between points was 6.0-16.8 mm (mean 9.9 mm; 10.6 mm). In visual assessment, most fusions were graded to be satisfactory or correctly fused: R1, R2: grade 3, 11/30 (36.7%), 22/30 (73.3%); grade 2, 13/30 (43.3%), 8/30 (26.7%); grade 1, 6/30 (20%), 0/30 (0%). Fusions were mostly comparable to hybrid PET/CT fusions. All of the fusions were defined as diagnostically relevant by both observers.
Retrospective rigid image fusion of FDG-PET and MRI of the upper abdomen using the CT-component of PET/CT for registration is feasible without adaptation in image acquisition protocols and shows sub-centimeter registration errors in most cases.
评估F-18氟脱氧葡萄糖正电子发射断层扫描（FDG-PET）与上腹部磁共振成像（MRI）之间回顾性刚性图像配准和融合的准确性。
患者、材料、方法：对30例怀疑肝脏或胰腺恶性肿瘤的患者进行PET和MRI图像融合。使用一种能够进行基于手动点的刚性配准的商用图像融合工具，通过在门静脉期采集的三维扰相梯度回波（GRE）MRI序列以及PET/CT的CT部分中匹配八个同源点，对PET图像进行回顾性配准和融合。两名独立观察者（R1、R2）通过确定x、y和z轴上的距离以及与用于配准的地标不同的解剖地标之间的绝对距离来评估图像配准的准确性。融合质量使用三点分级量表（1分：融合不佳；2分：融合满意；3分：融合正确）进行分级，并与PET/CT混合融合进行比较。
每位患者的平均配准时间少于2分钟。客观配准评估显示，x轴上的误差在2.4 - 6.3毫米之间：平均3.6毫米（R1）；4.6毫米（R2），y轴上的误差在2.3 - 9.3毫米之间（平均5.1毫米；5.5毫米），z轴上的误差在3.3 - 12.0毫米之间（平均5.9毫米；5.9毫米）。点之间绝对距离的平均误差为6.0 - 16.8毫米（平均9.9毫米；10.6毫米）。在视觉评估中，大多数融合被评为满意或正确融合：R1、R2：3级，11/30（36.7%），22/30（73.3%）；2级，13/30（43.3%），8/30（26.7%）；1级，6/30（20%），0/30（0%）。融合大多与PET/CT混合融合相当。两位观察者均将所有融合定义为具有诊断相关性。
使用PET/CT的CT部分进行配准，对上腹部FDG-PET和MRI进行回顾性刚性图像融合是可行的，无需调整图像采集协议，并且在大多数情况下显示出亚厘米级的配准误差。
