Elsevier

Lung Cancer

Volume 140, February 2020, Pages 80-86
Lung Cancer

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

https://doi.org/10.1016/j.lungcan.2019.10.032Get rights and content

Highlights

  • DECT has excellent diagnostic performance to assess SOM than that of PET/CT.

  • Pre-surgical DECT after whole-body PET/CT could improve the identification of SOM.

  • DECT after PET/CT should be recommended as a standard procedure to evaluate SOM.

Abstract

Objective

To determine the clinical value of 18F-FDG-PET/CT and dual-energy virtual noncalcium CT to detect and identify single osteolytic metastases (SOM) in participants with non-small cell lung cancer (NSCLC).

Materials and Methods

Forty-two participants (mean age, 63.5 years ± 10.1; range, 41–81 years) with suspected SOM diagnosed by whole-body 18F-FDG-PET/CT underwent non-enhanced dual-energy CT. All images were visually and quantitatively evaluated by two nuclear medicine physicians (R1 and R2) and two radiologists (R3 and R4) independently. The results of visual and quantitative analysis of 18F-FDG-PET/CT and dual-energy CT were compared with pathological results.

Results

In the visual analysis, the specificity and positive predictive value of dual-energy CT for reader 1 and reader 2 is larger than the corresponding figures of18F-FDG-PET/CT for reader 3 and reader 4 (94.1% each vs 82.4%/76.5%; 95.2%/95.0% vs 88.9%/86.2%). The sensitivity and negative predictive value of dual-energy CT is relatively lower than the number of 18F-FDG-PET/CT for readers (80.0%/76.0% vs 96.0%/100.0%; 76.2%/72.7% vs 93.3%/100.0%, respectively). ROI-based analysis of SUVmax on PET/CT images and CT numbers on VNCa images showed a significant difference between metastases and non-metastases (P < 0.001 each).

Conclusions

Pre-surgical evaluation by combination of whole-body 18F-FDG-PET/CT and dual-energy CT could improve the classification of SOM and may further guide the surgical decision-making in participants with NSCLC.

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.

Section snippets

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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