Application of <sup>18</sup>F‐FDG PET/CT in Langerhans Cell Histiocytosis
Fengxiang Liao, Zhehuang Luo, Zizhen Huang, Rong Xu, Wanling Qi, Mingyan Shao, Pinggui Lei, Bing Fan
Abstract
Purpose . This study aims to explore the application value of the 18 F‐FDG PET/CT imaging in diagnosing, staging, and typing Langerhans cell histiocytosis (LCH) via the morphological and metabolic analyses of the 18 F‐FDG PET/CT images. Methods . We retrospectively analyzed the 18 F‐FDG PET/CT images and clinical data of nineteen patients with LCH. The shape, size, density, distribution, and 18 F‐FDG uptake of all lesions were documented. In addition, the SUVmax of the lesions, liver, and blood pool was measured prior to calculating the lesion‐to‐liver and lesion‐to‐blood pool ratios. Results . Among the 19 analyzed patients, the positive rate of the PET/CT image was 94.7% (18/19), with 1 false negative (5.3%, 1/19) case occurring in the cutaneous LCH. Among the 76 lesions, 69 were FDG‐avid lesions (69/76, 90.8%). Additionally, we observed no FDG uptake in 7 lesions (7/76, 9.2%). In contrast, 59 lesions (59/76, 77.6%) were abnormal on diagnostic CT scan, but 17 lesions (17/76, 22.4%) were undetected. The 18 F‐FDG PET/CT image revealed additional 6 lesions in the bone, 4 in the lymph node, 3 in the spleen, and 3 occult lesions, which CT scan did not detect. Additionally, there were 6 cases with single‐system LCH. The remaining 13 cases were multisystem LCH. Our 18 F‐FDG PET/CT image analyses altered the typing of 4 LCH patients. In the case of all lesions, the mean SUVmax of the 18 F‐FDG‐avid lesions was 5.4 ± 5.1 (range, 0.8∼26.2), and the mean lesion‐to‐liver SUVmax ratio was 3.1 ± 2.52 (range, 0.7∼11.9), and the mean lesion‐to‐blood pool SUVmax ratio was 4.6 ± 3.4 (range 0.7∼17.5). Conclusion . The 18 F‐FDG PET/CT image plays an essential role in LCH diagnosis, primary staging, and typing. It can accurately evaluate the distribution, range, and metabolic information of LCH, providing a vital imaging basis for the clinical evaluation of disease conditions, selection of treatment schemes, and determining patient prognosis.