Etchebehere E C S C, Macapinlac H A, Gonen M, Humm K, Yeung H W D, Akhurst T, Scher H I, Larson S M
Nuclear Medicine Service, Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, USA.
Q J Nucl Med. 2002 Jun;46(2):122-30.
Recently, iterative reconstruction with segmented attenuation corrections (IRSAC) has been introduced for reconstruction of (18)F-FDG PET images. IRSAC produces images that are more pleasing to the eye, but qualitative and quantitative comparisons between IRSAC and filtered back projection (FBP) have not been reported for metastatic cancer. Since quantitative data has been widely used as an adjunct to interpretation of PET scans, comparison between IRSAC and FBP is needed. The purpose of this study was to compare image quality and the maximum standardized uptake value (SUVmax) obtained with FBP and with IRSAC in metastatic lesions from prostate cancer.
Twenty (18)F-FDG PET scans (10 baseline and 10 follow-up) were performed in 10 patients with prostate cancer (ages 66-85 yrs, mean 73.6 yrs). Acquisition began 45 min after injection of 370 MBq of (18)F-FDG. Images were reconstructed using FBP and IRSAC, and submitted to visual and quantitative analysis. SUVmax was obtained for all metastases, on FBP and IRSAC. A Jaszczak phantom study was also performed.
IRSAC images showed better image quality than FBP especially in regions of high activity concentrations. IRSAC detected 106 lesions on both baseline and follow-up scans, while FBP detected 100 and 95 lesions on baseline and follow-up scans, respectively. Therefore, 17 more lesions were seen on IRSAC. The mean SUVmax values on baseline scans for FBP and IRSAC were systematically different, at 4.46+/-1.99 and 5.13+/-2.67, respectively. On follow-up scans values were 3.89+/-1.72 for FBP and 4.29+/-1.93 for IRSAC. Comparison of FBP with IRSAC on baseline and follow-up scans were statistically significant (baseline: paired "t"-test p=0.0017; follow-up: paired "t"-test p=0.0008). Phantom studies reveal that these differences can be explained by the type of reconstruction filters used, and IRSAC was more accurate than FBP.
IRSAC detects smaller volumes in phantoms, patient images are easier to interpret and more metastatic lesions were detected. In addition, IRSAC provides reproducible quantitative data, comparable to data provided by FBP. IRSAC SUV and FBP SUV are in close agreement but there was a statistically significant difference between the two, and therefore threshold values of SUV will probably need to be re-determined with IRSAC, and are likely to be 10 to 19% higher than currently reported.
最近，用于（18）F - FDG PET图像重建的带分段衰减校正的迭代重建技术（IRSAC）已被引入。IRSAC生成的图像在视觉上更令人满意，但尚未有关于IRSAC与滤波反投影（FBP）在转移性癌症方面的定性和定量比较的报道。由于定量数据已被广泛用作PET扫描解读的辅助手段，因此需要对IRSAC和FBP进行比较。本研究的目的是比较FBP和IRSAC在前列腺癌转移灶中获得的图像质量和最大标准化摄取值（SUVmax）。
对10例前列腺癌患者（年龄66 - 85岁，平均73.6岁）进行了20次（18）F - FDG PET扫描（10次基线扫描和10次随访扫描）。在注射370 MBq的（18）F - FDG后45分钟开始采集。图像分别使用FBP和IRSAC进行重建，并进行视觉和定量分析。在FBP和IRSAC图像上获取所有转移灶的SUVmax。还进行了Jaszczak体模研究。
IRSAC图像显示出比FBP更好的图像质量，尤其是在高活性浓度区域。IRSAC在基线和随访扫描中均检测到106个病灶，而FBP在基线和随访扫描中分别检测到100个和95个病灶。因此，IRSAC多检测到17个病灶。FBP和IRSAC在基线扫描时的平均SUVmax值存在系统性差异，分别为4.46±1.99和5.13±2.67。在随访扫描中，FBP的值为3.89±1.72，IRSAC的值为4.29±1.93。FBP与IRSAC在基线和随访扫描中的比较具有统计学意义（基线：配对“t”检验p = 0.0017；随访：配对“t”检验p = 0.0008）。体模研究表明，这些差异可以用所使用的重建滤波器类型来解释，并且IRSAC比FBP更准确。
IRSAC在体模中能检测到更小的体积，患者图像更易于解读且检测到更多的转移灶。此外，IRSAC提供可重复的定量数据，与FBP提供的数据相当。IRSAC SUV和FBP SUV非常接近，但两者之间存在统计学上的显著差异，因此可能需要用IRSAC重新确定SUV的阈值，并且可能比目前报道的值高10%至19%。
