PET/CT Scan Shows High Diagnostic Accuracy for the Detection of Non-Small-Cell Lung Cancer Metastases

For patients with non-small-cell lung cancer (NSCLC), the accurate determination of the lymph node status before therapy is critical to develop a customized treatment plan.

New findings have highlighted a new approach for this information to be collected--a virtual fly-through, three-dimensional (3D) ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) bronchoscopy that has high diagnostic accuracy for the detection of regional lymph node metastases.

The study’s findings were published in the October 2011 issue of the Journal of Nuclear Medicine. According to Till A. Heusner, MD, from the department of radiology, University of Dusseldorf (Germany), and senior author of the study, “this is one of the first studies dealing with a virtual-bronchoscopy program that integrates functional information and anatomical data.”

To determine the effectiveness of the virtual bronchoscopy, researchers performed whole-body ¹⁸F-FDG PET/CT scans on 61 consecutive NSCLC patients. From the data collected, virtual ¹⁸F-FDG PET/CT bronchoscopies were reconstructed and diagnostic accuracy of detection of regional lymph node metastases was evaluated using the 18F-FDG PET/CT scans as a standard of reference. Researchers conducted their evaluation by measuring the mean duration time from the start of the virtual bronchoscopy until the images were displayed, maximum standardized uptake value (glucose metabolic activity) (SUVmax), SUVmean, short-axis diameter, and the distance of the airways of the regional lymph nodes.

Results from the virtual fly-through bronchoscopy showed that the diagnostic accuracy for the detection of lymph node metastases was 8%. The mean duration from the start of the virtual ¹⁸F-FDG PET/CT bronchoscopy tool until image display was 22 seconds, and the mean smallest diameter of accessible bronchi was 3 mm. The differences in the SUVmax, SUVmean, short-axis diameter, and distance to the airways among both true- and false-positive and true- and false-negative lymph nodes also were statistically significant. As such, the authors concluded that virtual ¹⁸F-FDG PET/CT bronchoscopy enables a noninvasive fly-through--even in comparatively small airways in the periphery of the lung--with high diagnostic accuracy.

According to Dr. Heusner, as a complement to PET/CT imaging, the software may be used in the future to virtually visualize the bronchial system before interventional procedures, to plan optical bronchoscopies and define regions where a bronchoscopy-guided biopsy may be most promising for sampling of malignant tissue. He added, “With the virtual fly-through three-dimensional ¹⁸F-FDG PET/CT bronchoscopy, nuclear medicine physicians may be able to present images that better meet the needs of the referring clinicians, as the tool simulates the bronchoscopic view a pulmonologist is accustomed to. This technique may also improve the process of acquiring tissue samples for characterization with emerging molecular diagnostics that can guide application of new targeted therapies in lung cancer.”

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University of Dusseldorf