Clinical utility of dual-energy CT used as an add-on to 18F FDG PET/CT in the preoperative staging of resectable NSCLC with suspected single osteolytic metastases
Introduction
Non–small-cell lung cancer (NSCLC) is the leading cause of cancer-related deaths worldwide [1]. Surgical resection of the lung mass with mediastinal lymph node sampling is the best treatment choice for NSCLC in patients without preoperative evidence of mediastinal invasion or distant metastasis [2]. Therefore, making accurate staging is crucial for selecting appropriate treatment after the diagnosis of NSCLC since patients with undetected distant metastases will not profit from radio-chemotherapy so a surgical procedure should therefore be recommended [3].
Recommended by various international guidelines, 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has been regarded as the most important imaging modality for whole-body staging of patients with NSCLC [1,2] and plays a crucial role in the pre-surgical evaluation for distant metastasis [4,5].
Bone metastases occurred in NSCLC are usually osteolytic [6,7]. Although PET is easy to establish a staging diagnosis of distant metastasis for multiple bone lesions in patients with NSCLC, differentiation of single osteolytic metastases (SOM) from incidental and often nonspecific bone lesions is a common dilemma for nuclear medicine physicians or radiologists in the oncologic setting, especially for lesions with high FDG uptake [8].
Several studies have validated the ability of dual-energy CT with virtual noncalcium (VNCa) technique to provide powerful advantages regarding bone marrow lesions detection with high sensitivity and specificity [[9], [10], [11], [12], [13], [14], [15]]. More recently, it is also predicted that dual-energy CT may provide further data to differentiate bone metastases from incidental and nonspecific bone lesions [16].
Dual-energy CT acquires two CT data sets at different energy levels simultaneously, and can subsequently quantify and remove the individual chemical elements, like calcium, from those data sets. Calcium is then removed from trabecular bone by using VNCa subtraction process by postprocessing software [[9], [10], [11], [12]]. Increased water content due to the relatively increased vascular permeability of malignant tissue or infiltrating cellular components (bone metastases) in the bone marrow can be seen on VNCa images [16,17].
We prospectively compared the accuracy of whole-body PET/CT with that of time-matched selected regionalized dual-energy CT in the discrimination of suspected SOM in patients with NSCLC. We hypothesized that preoperative staging using dual-energy CT after whole-body 18F-FDG-PET/CT can be helpful to identify SOM and avoid misstaging in NSCLC patients for whom surgical therapy is an option. Thus, the purpose of our preoperative study was to evaluate the diagnostic performance and clinical impact of 18F-FDG-PET/CT and dual-energy CT to detect and identify suspected SOM in a group of patients with NSCLC selected for surgical treatment on the basis of conventional staging.
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Participants
Our prospective study was approved by the ethics committee of our hospital, and informed consent was obtained from all patients prior to examination. Between April 2016 and June 2018, 42 participants with NSCLC suspected SOM were prospectively enrolled in this study. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments
Results
Forty-two eligible participants with NSCLC consisting of 24 (57.1%) men and 18 (42.9%) women were enrolled in this study presented with a solitary osteolytic lesion. Patient demographics and lesion characteristics are outlined in Table 1.
Declaration of Competing Interest
No potential conflicts of interest relevant to this article exist. One author (L.S.) is an employee of Siemens Healthcare. Authors who are not employees of or consultants for Siemens had control of inclusion of any data and information that might present a conflict of interest for the author who is an employee of that company.
Financial support
This work was supported by grants from Natural Science Foundation of Guangdong Province (nos. 2017A020215192), and Guangzhou Science and Technology Project (CN) (nos. 201,804,010,049), and Guangdong Provincial People's Hospital "Dengfeng Plan" scientific research project (DFJH201912) P.R. China.
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2022, Respiratory Medicine Case ReportsCitation Excerpt :In general, non-small-cell lung cancer (NSCLC) causes osteolytic bone metastases, but it has been reported that 16% of patients with NSCLC can present with sclerotic bone metastases at initial diagnosis [11], suggesting that sclerotic changes are not a rare metastatic pattern in NSCLC. Furthermore, the sensitivity of FDG-PET has been reported to be decreased in sclerotic bone metastases [12], and the possibility of bone metastases should be considered in NSCLC when sclerotic lesions are found in the bone, even if FDG accumulation is poor. In the current case, the FDG accumulation observed in sclerotic bone lesions was difficult to differentiate from bone metastases.
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Contributed equally to this work.