PET-CT in the staging and treatment of non-small-cell lung cancer

Abstract

Positron emission tomography with 2-((18)F)-fluoro- 2-deoxy-D-glucose (FDG-PET) is a metabolic imaging technique. FDG-PET is more accurate than CT for the evaluation of mediastinal involvement in patients with nonsmall- cell lung cancer, offering a high negative predictive value. It can detect occult metastases in 11% of patients, although the etiology of the extrathoracic isolated uptakes needs confirmation. Theoretically, FDG-PET can influence the planning volume for radiotherapy, primarily in patients with atelectasis. Quantification of metabolic activity using FDG-PET is influenced by the size of the lesion, glucose levels and the time elapsed since the isotope injection. More clinical trials are required to standardize the methods for performing PET, assess its use as a prognostic factor and for the evaluation of treatment response.

Ratio of Lymph Node to Primary Tumor SUV on PET/CT Accurately Predicts Nodal Malignancy in Non–Small-Cell Lung Cancer

“…For instance, the partial volume effect (PVE), which is a consequence of the finite spatial resolution of the PET/CT scanner resulting in underestimation of the SUV of smaller lesions less than approximately 3cm in size (depending on several scanner-specific features) has the potential to generate false negatives, particularly when a lymph node in question is much smaller than a primary tumor or when assessing a lymph node containing only microscopic tumor deposits. 5 Along these lines, Gould et al showed that a smaller lymph node is more likely to be malignant than a larger lymph node when both have the same SUV. 10 This well-described phenomenon suggests that in order to derive clinically relevant information from the SUV of smaller lesions, one should correct the SUV for the size of the lesion.…”

“…[21][22] Since false negatives and positives would be most common for an SUV close to a cutoff value, we selected the range of SUV max of 2.0 -6.0 for analysis so as to be inclusive of most commonly reported cutoff values of SUV max , which have typically ranged from 2.5 -5.3 in reported series. [3][4][5][6][7][8][9][10] Patients with a history of prior chemotherapy, radiation therapy, granulomatous disease, or non-skin cancer malignancy were excluded. Nodal pathology could be obtained by any means, including excisional biopsy (via mediastinoscopy, thoracotomy, etc.)…”

“…It should be noted that no previous clinical publications have applied PVE corrections to lymph node staging, which is yet another important reason for the heterogeneous sensitivities and specificities reported for nodal staging using SUV. [3][4][5][6][7][8][9][10] Respiratory motion of the tumor and lymph nodes would also affect SUV during acquisition of the scan, and motion-corrected imaging is a topic of ongoing research and beyond the scope of this manuscript. 35 Finally, it could be argued that our analysis would inherently favor the SUV ratio over SUV max simply because a variety of scanners at different imaging centers were included in this study, and the performance of SUV max is disproportionately affected by the scanner hardware and reconstruction approaches.…”

“…2 Functional imaging with PET (co-registered with CT) is more accurate than CT alone in predicting nodal pathology, though even the most widely used cutoff value suggestive of malignancy, a maximum standardized uptake value (SUV max ) >2.5, is also associated with a wide range of sensitivity (40-97%) and specificity (60-96%) in multiple series. [3][4][5][6][7][8][9][10] One explanation for this wide range is that these studies were performed in different patient populations and used varying criteria for malignancy in order to increase either the sensitivity or specificity of the imaging test. Additionally, while SUV is standardized for a patient's weight and the amount of FDG administered, it does not take into account a plethora of other patient, tumor, and technique-specific factors, which contribute to a measured variability in the absolute SUV on the order of 10-20%.…”

PET Imaging of Neovascularization with 68Ga-3PRGD2 for Assessing Tumor Early Response to Endostar Antiangiogenic Therapy

“…14 Among several molecular imaging modalities, positron emission tomography (PET) is a promising technology that allows noninvasive imaging of tumor angiogenesis at the molecular level. 15 18 F-FDG is the most commonly used PET imaging agent and has been successfully applied for the diagnosis of many diseases worldwide. 16 However, 18 F-FDG is not a tumor-specific radiotracer and can lead to a false-positive in various forms of infection, inflammation, and granulomatous disease.…”