Fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) computed tomography (CT) for the detection of bone, lung and lymph node metastases in rhabdomyosarcoma

Diagnostic Accuracy of FDG PET-CT in Lymph Nodal Staging of Lung Cancer

Background Lymph node staging is a critical component in managing lung cancer, as it determines prognosis and guides treatment decisions. Fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) has emerged as a highly sensitive and specific imaging modality for evaluating nodal involvement, surpassing conventional imaging techniques. Therefore, this study evaluated the diagnostic accuracy of PET-CT in lymph nodal staging of lung cancer, using histopathology as the gold standard. Methodology This cross-sectional study was conducted at the Radiology and PET Scan Department, Jinnah Postgraduate Medical Centre (JPMC), Karachi, over six months, from January 28, 2021, to July 28, 2021, using a non-probability consecutive sampling. It included 127 biopsy-proven lung cancer patients aged 21-80 years. FDG PET-CT scans were evaluated by an experienced radiologist, with findings compared against histopathology results after surgery and biopsy. Using IBM SPSS Statistics for Windows, Version 22 (Released 2013; IBM Corp., Armonk, New York, United States), data analysis included calculating the sensitivity, specificity, and predictive values of FDG PET-CT for nodal metastasis, with histopathology as the gold standard. Results The study findings showed that out of 127 lung cancer patients, with a mean age of 54.14 ± 10.41 years, 99 (78.0%) were male, and 111 (87.4%) were aged >40 years. Symptoms persisted for a mean of 12.04 ± 6.82 weeks, and 88 (69.30%) had standardized uptake value (SUV)>3.0. Nodal staging showed N1 nodes in 64 (50.40%), N2 in 37 (29.10%), and N3 in 26 (20.50%). PET-CT detected nodal metastasis in 89 (70.18%) of cases, with histopathology confirming metastasis in 95 (74.88%). PET-CT achieved a sensitivity of 91.50%, specificity of 93.75%, positive predictive value (PPV) of 97.75%, and negative predictive value (NPV) of 78.95%. The overall accuracy of PET-CT was 92.13%, with a strong correlation to histopathology, emphasizing its reliability in staging nodal metastasis. Conclusion This study concluded the high diagnostic accuracy of PET-CT in detecting nodal metastasis in lung cancer, with an overall accuracy of 92.13%. PET-CT demonstrated excellent sensitivity (91.50%) and specificity (93.75%). These results confirm PET-CT as a reliable imaging modality for lymph nodal staging.

Fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) computed tomography (CT) for the detection of bone, lung, and lymph node metastases in rhabdomyosarcoma

BACKGROUND

Rhabdomyosarcoma (RMS) is the most common paediatric soft-tissue sarcoma and can emerge throughout the whole body. For patients with newly diagnosed RMS, prognosis for survival depends on multiple factors such as histology, tumour site, and extent of the disease. Patients with metastatic disease at diagnosis have impaired prognosis compared to those with localised disease. Appropriate staging at diagnosis therefore plays an important role in choosing the right treatment regimen for an individual patient. Fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) is a functional molecular imaging technique that uses the increased glycolysis of cancer cells to visualise both structural information and metabolic activity. 18F-FDG-PET combined with computed tomography (CT) could help to accurately stage the extent of disease in patients with newly diagnosed RMS. In this review we aimed to evaluate whether 18F-FDG-PET could replace other imaging modalities for the staging of distant metastases in RMS.

OBJECTIVES

To determine the diagnostic accuracy of 18F-FDG-PET/CT imaging for the detection of bone, lung, and lymph node metastases in RMS patients at first diagnosis.

SEARCH METHODS

We searched MEDLINE in PubMed (from 1966 to 23 December 2020) and Embase in Ovid (from 1980 to 23 December 2020) for potentially relevant studies. We also checked the reference lists of relevant studies and review articles; scanned conference proceedings; and contacted the authors of included studies and other experts in the field of RMS for information about any ongoing or unpublished studies. We did not impose any language restrictions.

SELECTION CRITERIA

We included cross-sectional studies involving patients with newly diagnosed proven RMS, either prospective or retrospective, if they reported the diagnostic accuracy of 18F-FDG-PET/CT in diagnosing lymph node involvement or bone metastases or lung metastases or a combination of these metastases. We included studies that compared the results of the 18F-FDG-PET/CT imaging with those of histology or with evaluation by a multidisciplinary tumour board as reference standard.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, data extraction, and methodological quality assessement according to Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). We analysed data for the three outcomes (nodal involvement and lung and bone metastases) separately. We used data from the 2 × 2 tables (consisting of true positives, false positives, true negatives, and false negatives) to calculate sensitivity and specificity in each study and corresponding 95% confidence intervals. We did not consider a formal meta-analysis to be relevant because of the small number of studies and substantial heterogeneity between studies.

MAIN RESULTS

Two studies met our inclusion criteria. The diagnostic accuracy of 18F-FDG-PET/CT was reported in both studies, which included a total of 36 participants. We considered both studies to be at high risk of bias for the domain reference standard. We considered one study to be at high risk of bias for the domain index test and flow and timing. Sensitivity and specificity of 18F-FDG-PET/CT for the detection of bone metastases was 100% in both studies (95% confidence interval (CI) for sensitivity was 29% to 100% in study one and 40% to 100% in study two; 95% CI for specificity was 83% to 100% in study one and 66% to 100% in study two). The reported sensitivity of 18F-FDG-PET/CT for the detection of lung metastases was not calculated since only two participants in study two showed lung metastases, of which one was detected by 18F-FDG-PET/CT. Reported specificity was 96% in study one (95% CI 78% to 100%) and 100% (95% CI 72% to 100%) in study two. The reported sensitivity for the detection of nodal involvement was 100% (95% CI 63% to 100% in study one and 40% to 100% in study two); the reported specificity was 100% (95% CI 78% to 100%) in study one and 89% (95% CI 52% to 100%) in study two.

AUTHORS' CONCLUSIONS

The diagnostic accuracy of 18F-FDG-PET/CT for the detection of bone, lung, and lymph node metastases was reported in only two studies including a total of only 36 participants with newly diagnosed RMS. Because of the small number of studies (and participants), there is currently insufficient evidence to reliably determine the diagnostic accuracy of 18F-FDG-PET/CT in the detection of distant metastases. Larger series evaluating the diagnostic accuracy of 18F-FDG-PET/CT for the detection of metastases in patients with RMS are necessary.