Nuclear Medicine Unit, Second Faculty of Medicine, Sapienza University of Rome, Rome, Italy.
J Nucl Med. 2011 Jul;52(7):1012-9. doi: 10.2967/jnumed.110.082222. Epub 2011 Jun 16.
White blood cell (WBC) scintigraphy is considered the nuclear medicine imaging gold standard for diagnosing osteomyelitis in the diabetic foot. Recent papers have suggested that the use of (18)F-FDG PET/CT produces similar diagnostic accuracy, but clear interpretation criteria have not yet been established. Our aim was to evaluate the role of sequential (18)F-FDG PET/CT in patients with a high suspicion of osteomyelitis to define objective interpretation criteria to be compared with WBC scintigraphy.
Thirteen patients whom clinicians considered positive for osteomyelitis (7 with ulcers, 6 with exposed bone) were enrolled. The patients underwent (99m)Tc-exametazime WBC scintigraphy with acquisition times of 30 min, 3 h, and 20 h and sequential (18)F-FDG PET/CT with acquisition times of 10 min, 1 h, and 2 h. A biopsy or tissue culture was performed for final diagnosis. Several interpretation criteria (qualitative and quantitative) were tested.
At final biopsy, 7 patients had osteomyelitis, 2 had soft-tissue infection without osteomyelitis, and 4 had no infection. The best interpretation criterion for osteomyelitis with WBC scintigraphy was a target-to-background (T/B) ratio greater than 2.0 at 20 h and increasing with time. A T/B ratio greater than 2.0 at 20 h but stable or decreasing with time was suggestive of soft-tissue infection. A T/B ratio of no more than 2.0 at 20 h excluded an infection. Thus, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for osteomyelitis were 86%, 100%, 100%, 86%, and 92%, respectively. For (18)F-FDG PET/CT, the best interpretation criterion for osteomyelitis was a maximal standardized uptake value (SUVmax) greater than 2.0 at 1 and 2 h and increasing with time. A SUVmax greater than 2.0 after 1 and 2 h but stable or decreasing with time was suggestive of a soft-tissue infection. An SUVmax less than 2.0 excluded an infection. (18)F-FDG PET at 10 min was not useful. Using these criteria, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for osteomyelitis were 43%, 67%, 60%, 50%, and 54%, respectively. Combining visual assessment of PET at 1 h and CT was best for differentiating between osteomyelitis and soft-tissue infection, with a diagnostic accuracy of 62%.
(18)F-FDG PET/CT, even with sequential imaging, has a low diagnostic accuracy for osteomyelitis and cannot replace WBC scintigraphy in patients with diabetic foot.
评估高怀疑骨髓炎患者连续（18）F-FDG PET/CT 的作用，以确定与白细胞闪烁扫描相比的客观解释标准。
纳入了 13 名临床医生认为患有骨髓炎（7 例溃疡，6 例暴露骨）的患者。患者接受（99m）Tc-exametazime 白细胞闪烁扫描，采集时间为 30 分钟、3 小时和 20 小时，以及连续（18）F-FDG PET/CT，采集时间为 10 分钟、1 小时和 2 小时。最终诊断采用活检或组织培养。测试了几种解释标准（定性和定量）。
在最终的活检中，7 例患者患有骨髓炎，2 例患有软组织感染但无骨髓炎，4 例无感染。白细胞闪烁扫描诊断骨髓炎的最佳解释标准是 20 小时时靶/背景（T/B）比值大于 2.0，且随时间增加。20 小时时 T/B 比值大于 2.0，但随时间稳定或降低提示软组织感染。20 小时时 T/B 比值不超过 2.0 可排除感染。因此，骨髓炎的敏感性、特异性、阳性预测值、阴性预测值和准确性分别为 86%、100%、100%、86%和 92%。对于（18）F-FDG PET/CT，骨髓炎的最佳解释标准是 1 小时和 2 小时时最大标准化摄取值（SUVmax）大于 2.0，且随时间增加。1 小时和 2 小时后 SUVmax 大于 2.0，但随时间稳定或降低提示软组织感染。SUVmax 小于 2.0 可排除感染。（18）F-FDG PET 在 10 分钟时无用处。使用这些标准，骨髓炎的敏感性、特异性、阳性预测值、阴性预测值和准确性分别为 43%、67%、60%、50%和 54%。PET 在 1 小时时的视觉评估与 CT 相结合，是区分骨髓炎和软组织感染的最佳方法，诊断准确性为 62%。
（18）F-FDG PET/CT 即使进行连续成像，对骨髓炎的诊断准确性也较低，不能替代糖尿病足患者的白细胞闪烁扫描。
