Clinical role of F-18 fluorodeoxyglucose positron emission tomography imaging in patients with lung cancer and suspected malignant pleural effusion

Noninvasive staging of non-small cell lung cancer: ACCP evidenced-based clinical practice guidelines (2nd edition)

BACKGROUND

Correctly staging lung cancer is important because the treatment options and the prognosis differ significantly by stage. Several noninvasive imaging studies including chest CT scanning and positron emission tomography (PET) scanning are available. Understanding the test characteristics of these noninvasive staging studies is critical to decision making.

METHODS

Test characteristics for the noninvasive staging studies were updated from the first iteration of the lung cancer guidelines using systematic searches of the MEDLINE, HealthStar, and Cochrane Library databases up to May 2006, including selected metaanalyses, practice guidelines, and reviews. Study designs and results are summarized in evidence tables.

RESULTS

The pooled sensitivity and specificity of CT scanning for identifying mediastinal lymph node metastasis were 51% (95% confidence interval [CI], 47 to 54%) and 85% (95% CI, 84 to 88%), respectively, confirming that CT scanning has limited ability either to rule in or exclude mediastinal metastasis. For PET scanning, the pooled estimates of sensitivity and specificity for identifying mediastinal metastasis were 74% (95% CI, 69 to 79%) and 85% (95% CI, 82 to 88%), respectively. These findings demonstrate that PET scanning is more accurate than CT scanning. If the clinical evaluation in search of metastatic disease is negative, the likelihood of finding metastasis is low.

CONCLUSIONS

CT scanning of the chest is useful in providing anatomic detail, but the accuracy of chest CT scanning in differentiating benign from malignant lymph nodes in the mediastinum is poor. PET scanning has much better sensitivity and specificity than chest CT scanning for staging lung cancer in the mediastinum, and distant metastatic disease can be detected by PET scanning. With either test, abnormal findings must be confirmed by tissue biopsy to ensure accurate staging.

Staging non-small cell lung cancer

Patients with newly diagnosed non-small cell lung cancer (NSCLC) need accurate tumor staging in order to direct appropriate therapy and establish prognosis; the tumor is usually staged using the TNM system. The major imaging modalities currently used for staging this disease are thoracic computed tomography (CT) (including the adrenal glands) and whole body fluorodeoxyglucose (FDG)-positron emission tomography (PET) scanning. CT is generally most useful in evaluating the T stage, i.e. local spread of the neoplasm, whereas PET is most helpful in assessing the N and M stages, i.e. regional and distant tumor spread, respectively. Integrated CT-PET imaging adds information compared to the use of either modality alone. PET findings frequently lead to upstaging the disease and thus prevent unindicated surgeries. Magnetic resonance imaging (MRI) is helpful in evaluating local extent of disease in patients with superior sulcus tumors and possible brachial plexus involvement. Staging accuracy using any of these imaging techniques is imperfect; therefore, pathologic confirmation of positive findings is recommended, whenever possible, before denying a patient potentially curative therapy.

Staging of Lung Cancer

Imaging techniques play a vital role in the diagnosis, staging, and follow-up of patients who have lung cancer. For this purpose, PET has become an important adjunct to conventional imaging techniques such as chest radiography, CT, ultrasonography, and MR imaging. The ability of PET to differentiate the metabolic properties of tissues allows more accurate assessment of undetermined lung lesions, mediastinal lymph nodes, or extrathoracic abnormalities, tumor response after induction treatment, and detection of disease recurrence.

Positron emission tomography in the management of lung cancer

(18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a useful technique to characterize the solitary pulmonary nodule, diagnose primary lung cancer, carry out mediastinal and extrathoracic staging, plan radiotherapy, therapeutic response assessment and detect recurrence. PET may help to determine the ideal site for tissue diagnosis as well as predict prognosis. Combined PET and computed tomography (PET/CT) has the best of both worlds of metabolic and anatomic imaging and may provide optimal disease assessment.

PET/CT in non-small cell lung cancer staging—promises and problems

Integrated positron emission tomography/computed tomography (PET/CT) has many advantages over solitary PET and CT, which has led it to become an increasingly established imaging technique in the management of many cancers. This article will review the evidence for the role of (18)F-fluorodeoxyglucose PET/CT in non-small cell lung cancer staging, examining its strengths, weaknesses and cost-effectiveness.

Il versamento pleurico: aspetti eziologici, diagnostici e clinici

Il coinvolgimento della pleura puÒ comparire nel corso di molteplici e differenti patologie. Le cause che sottendono un versamento pleurico possono essere intra-toraciche o sistemiche e, se in alcuni casi queste appaiono facilmente individuabili grazie a segni clinici patognomonici, in altri casi l’inquadramento nosografico di un versamento puÒ risultare complesso, dovendosi basare su elementi clinici e reperti laboratoristico-strumentali spesso aspecifici.

18F-FDG PET imaging in assessing exudative pleural effusions

BACKGROUND

This study evaluates the accuracy of [F]fluorodeoxyglucose positron emission tomography (F-FDG PET) imaging with semi-quantitative analysis for differentiating benign from malignant pleural exudates and for guiding the search for the primary tumour of pleural metastases.

METHODS

Whole-body 18F-FDG PET was performed in 79 patients with exudative pleurisy. Standard uptake values were normalized for body weight, body surface area, lean body mass (SUVbw, SUVbsa, SUVlbm) with and without correction for blood glucose levels. Thoracoscopy was systematically performed to reveal pathological diagnosis.

RESULTS

All SUVs were significantly higher in all malignant pleural diseases (n = 51) than in benign (n = 28) (P < 0.001). Moreover SUVs were greater in the pleural metastases from pulmonary primaries (n = 25) and in mesotheliomas (n = 8) than in extrathoracic primaries (n = 18) (P < 0.01) with no significant difference between lung cancers and mesotheliomas. Receiver operating curve (ROC) analysis between benign and malignant lesions showed areas under the curves that ranged from 0.803 (SUVbsa g) to 0.863 (SUVbw). The cut-off value for SUVbw which gave the best accuracy (82.3%) was 2.2. When comparing thoracic with extrathoracic primaries the highest accuracy (80.4%) was found for a cut-off value of 2.6.

CONCLUSION

Semi-quantitative analysis of 18F-FDG PET imaging helps to differentiate malignant from benign pleural exudates and to distinguish between thoracic or extrathoracic primaries.

Integrated PET/CT and the Dry Pleural Dissemination of Peripheral Adenocarcinoma of the Lung

OBJECTIVE

The aim of this study was to describe retrospectively the CT findings of dry pleural dissemination of peripheral lung adenocarcinoma, and to compare the mutual roles of PET and CT components of integrated PET/CT in the diagnosis of the disease.

METHODS

The authors analyzed retrospectively the CT findings of pathologically proved dry pleural dissemination in 8 of 172 patients with peripheral adenocarcinoma of the lung. Subsequently, one radiologist and one nuclear medicine physician (unaware of the CT and pathologic results) evaluated together in a random order the integrated PET/CT of 172 adenocarcinoma patients (8 with dry pleural dissemination and 164 without). They recorded the presence of pleural dissemination using PET images only and using both PET and CT images. The diagnostic accuracies with respect to the presence of pleural dissemination were evaluated.

RESULTS

The CT findings of dry pleural dissemination were pleural small nodules (n=8, 100%) (>or=6 in number in all patients; 198/204 nodules were <5 mm in diameter and 6/204 were 5-10 mm) and uneven (n=4, 50%) or band-like (n=3, 38%) fissural thickening. By PET only, the sensitivity, specificity, and accuracy of dry pleural dissemination were 25% (2/8), 90% (147/164), and 87% (149/172), respectively; by PET plus CT these were 100% (8/8), 100% (164/164), and 100% (172/172), respectively.

CONCLUSIONS

The CT findings of dry pleural dissemination are multiple small pleural nodules and uneven pleural thickening. Dry pleural dissemination should be diagnosed using CT findings at integrated PET/CT because lesions causing pleural dissemination without pleural effusion are usually beyond PET resolution.

Imaging of Metastatic Disease to the Thorax

Tumor imaging is at the forefront of radiology technology and is the focus of most cutting edge research. Radiologic applications for imaging of metastases are applied to initial staging, restaging after neoadjuvant therapy, and follow-up surveillance after therapy for tumor recurrence. CT is the routine imaging choice in staging, restaging, and detection of recurrence. Fluorodeoxyglucose-positron emission tomography has evolved as an imaging modality that further improves staging as well as the detection of recurrent and metastatic disease.

Differentiation Between Malignant and Benign Pleural Effusion in Patients With Extra-Pleural Primary Malignancies

OBJECTIVES

We sought to define an accurate diagnostic approach for differentiating benign from malignant pleural effusion on positron emission tomography-computed tomography (PET-CT).

MATERIAL AND METHODS

PET-CT studies of 31 patients with primary extrapleural malignancy and pleural effusion were reviewed retrospectively. CT parameters assessed were size and density (Hounsfield units, or HU) of the effusion and density (HU) and morphology of any solid pleural abnormality. Interpretation of PET data included review of the attenuation-corrected and nonattenuation-corrected images.

RESULTS

PET-CT parameters that were found to be significant in identifying malignant pleural effusion included focal increased uptake of 18-fluorodeoxyglucose in the pleura (P<0.0001) and the presence of solid pleural abnormalities on CT (P<0.002): the sensitivity was 86% and 71%, respectively, and the specificity was 90% for each of the 2 parameters. A PET-CT pattern composed of pleural uptake and increased effusion activity on nonattenuation-corrected images was associated with sensitivity of 95%, specificity of 80%, positive predictive value of 91%, negative predictive value of 89%, and accuracy of 90%.

CONCLUSIONS

On PET-CT, the presence of concomitant pleural abnormalities is the most accurate criterion in determining the malignant nature of pleural effusion.

State-of-the-art FDG-PET imaging of lung cancer

The D-glucose analog 2-(fluorine-18)-fluoro-2-deoxy-D-glucose (FDG) is the most commonly used radionuclide in positron emission tomography (PET) of lung cancer. FDG-PET is a molecular imaging technique that images the preferential accumulation of FDG in malignant tissues with increased metabolism. Although FDG-PET is sensitive in the detection of lung cancer, FDG is not tumor specific and may accumulate in a variety of nonmalignant conditions. Occasional false-negative results may also occur. Whole body FDG-PET is a useful noninvasive technique to stage known or suspected non-small-cell lung cancer. The results allow more efficient use of invasive methods for histopathological staging. The combined use of CT and PET in dual imaging increases the number of patients with correctly staged non-small-cell lung cancer. CT/PET is also useful in the assessment of recurrent or residual disease. Future imaging agents are being developed which may allow more selective accumulation of radiopharmaceutical in malignant tissues.

Evolving role of positron emission tomography in the management of patients with inflammatory and other benign disorders

Fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) has evolved from a research imaging modality assessing brain function in physiologic and pathologic states to a pure clinical necessity. It has been successfully used for diagnosing, staging, and monitoring a variety of malignancies. FDG-PET imaging also is evolving into a powerful imaging modality that can be effectively used for the diagnosis and monitoring of a certain nononcological diseases. PET has been shown to be very useful in the diagnosis of osteomyelitis, painful prostheses, sarcoidosis, fever of unknown etiology, and acquired immunodeficiency syndrome. Based on recent observations, several other disorders, such as environment-induced lung diseases, atherosclerosis, vasculitis, back pain, transplantation, and blood clot, can be successfully assessed with this technique. With the development and the introduction of several new PET radiotracers, it is expected that PET will secure a major role in the management of patients with inflammatory and other benign disorders.

Fluorodeoxyglucose-PET in characterizing solitary pulmonary nodules, assessing pleural diseases, and the initial staging, restaging, therapy planning, and monitoring response of lung cancer

Fluorodeoxyglucose-PET imaging has secured an important role in the assessment and management of a multitude of pulmonary disorders, including solitary pulmonary nodules, lung cancer, and pleural diseases. While conventional imaging modalities such as chest radiography and CT are considered essential in these settings, FDG-PET can provide new information and complement structural imaging techniques in the evaluation of such disorders. In this review, the authors present a growing body of evidence that demonstrates and supports the utility of FDG-PET in the differentiation of benign and malignant pulmonary nodules, the assessment of lung cancer in various stages of disease, and the characterization of pleural diseases. In addition, new developments--such as prospects for potential utility of novel radiotracers and delayed imaging--that can further refine the role of FDG scans in the work-up of lung nodules and cancer and forecast the future place of PET in these common modalities are discussed.

The Role of PET Scan in Diagnosis, Staging, and Management of Non‐Small Cell Lung Cancer

Positron emission tomography (PET) is now an important cancer imaging tool, both for diagnosis and staging, as well as offering prognostic information based on response. This report attempts to comprehensively review the value of PET in the locoregional and distant staging of non-small cell lung cancer (NSCLC), illustrate the potential effects on patient management, and give a short overview of newer applications. PET sets the gold standard in the evaluation of an indeterminate solitary pulmonary nodule or mass, where PET has proven to be significantly more accurate than computed tomography (CT) in the distinction between benign and malignant lesions. In the evaluation of metastatic spread to locoregional lymph nodes, PET is significantly more accurate than CT, so that invasive surgical staging may be omitted in many patients with negative mediastinal PET images. In patients with positive mediastinal PET images, invasive surgical staging remains mandatory because of the possibility of false-positive findings due to inflammatory nodes or granulomatous disorders. In the search for metastatic spread, PET is a useful adjunct to conventional imaging. This may be due to the finding of unexpected metastatic lesions or due to exclusion of malignancy in lesions that are equivocal on standard imaging. However, at this time, PET does not replace conventional imaging. Large-scale randomized studies are currently examining whether PET staging will actually improve the appearance of lung cancer outcome.

Radiology in pleural disease: State of the art

Diseases of the pleura and pleural space are common and present a significant contribution to the workload of the chest radiologist. The radiology department plays a crucial role in the imaging and management of pleural disease. This review aims to describe and illustrate the appearances of common pleural pathologies on various radiological modalities including plain film, ultrasound, CT, magnetic resonance imaging and positron emission tomography. The review will also address the state-of-the-art techniques used to image pleural disease and discuss image-guided intervention in the management of pleural disease.

Fluorodeoxyglucose Positron Emission Tomography and CT After Talc Pleurodesis

BACKGROUND

Talc pleurodesis is widely performed for the management of persistent pneumothorax or pleural effusion, particularly malignant effusions. However, there are very few data characterizing fluorodeoxyglucose (FDG)-positron emission tomography (PET) and CT findings after treatment.

METHODS

We retrospectively evaluated the FDG-PET and CT studies of nine patients who underwent talc pleurodesis for the treatment of malignant pleural effusions or persistent air leak.

RESULTS

FDG-PET studies were performed on average 22 months after talc pleurodesis, and the mean CT follow-up period was 25 months. There was moderate-to-intense plaque-like or focal nodular-increased FDG uptake in the pleura on PET with mean standardized uptake value of 5.4 (SEM, 1.2; range, 2.0 to 16.3). The FDG uptake was either diffuse (two patients) or focal (seven patients), and most commonly occurred in the posterior costophrenic angles (five patients), followed by the apical regions (three patients), anterior costophrenic angle (one patient), and the anterior chest wall (one patient). On CT, high-density areas of pleural thickening or nodularity (mean, 230 Hounsfield units [HU]; SEM, 23 HU; range, 140 to 380 HU) corresponded to regions of increased FDG uptake. These pleural foci had an average thickness of 1.2 cm and measured up to 8.2 cm (mean, 7.1 cm) in length. Rounded pleural nodules were as large as 3.1 cm (mean, 1.5 cm).

CONCLUSIONS

Talc pleurodesis produces increased FDG uptake on PET and high-density areas of pleural thickening on CT that remain unchanged on serial imaging. When PET detects increased uptake in the pleural space, correlation with CT is recommended to detect the presence of pleural thickening of increased attenuation that suggests talc deposits rather than tumor.

Evaluation of Pleural Disease With 18-Fluorodeoxyglucose Positron Emission Tomography Imaging

STUDY OBJECTIVES

To study the ability of positron emission tomography (PET) using 18-fluorodeoxyglucose (FDG) to distinguish between benign and malignant disease in exudative pleural effusions and pleural thickening.

DESIGN

Prospective study of 98 consecutive patients presenting with either pleural thickening or an exudative pleural effusion.

SETTING

Department of pulmonary medicine of a university hospital.

METHODS

FDG-PET was performed on each subject before invasive procedures were used to determine the etiologic diagnosis. FDG-PET data were analyzed by visual interpretation.

RESULTS

Sixty-three of 98 patients were found to have malignant pleural disease after histologic analysis. Sixty-one of 63 patients with histologically confirmed malignant disease showed FDG uptake within the area of pleural thickening. Uptake was graded as intense in 51 cases and moderate in 10 cases. Only two patients with malignant pleural disease did not show increased FDG uptake. FDG-PET imaging showed an absence of FDG uptake, and correctly classified 31 of 35 benign lesions. For the remaining four lesions, intense FDG uptake was seen in one case of parapneumonic effusion, while moderate and localized uptake was observed in one parapneumonic, one tuberculous, and one uremic pleurisy. The sensitivity of the method to identify malignancy was 96.8% with a negative predictive value of 93.9%, while its specificity was 88.5% and its positive predictive value was 93.8%.

CONCLUSIONS

Our results suggest that FDG-PET is an effective tool for differentiating between benign and malignant pleural diseases.

Positron emission tomography in the management of non–small cell lung cancer

In the past 10 years, FDG-PET has become an important imaging modality in NSCLC. Its indication in the assessment of lung nodules and staging is based on large prospective experience, further supported by some meta-analyses. This evidence has important consequences for patient management, which recently was proved in a randomized trial that showed a reduction in the number of futile thoracotomies by preoperative PET. The use of FDG-PET could become more widespread when commercial isotope distributors are able to deliver FDG so that an on-site cyclotron is no longer a prerequisite. FDG has a half-life of 110 minutes, so a practical distribution radius of 200 km should be feasible. Current indications for PET in the staging of newly diagnosed NSCLC are mainly the patients who are considered to be candidates for radical treatment. The technique does not have a clinical indication in other patients--for example, when metastatic lymph nodes are detected at clinical examination, when a simple ultrasound study already points to diffuse hepatic metastases, or in cases of poor performance status. PET also has prognostic value; it can be used for the evaluation of response or restaging after radiotherapy or chemotherapy and for early detection of relapse. The combination of CT and PET improves radiotherapy planning and it is to be expected that combined CT-PET-guided planning devices will further refine three-dimensional conformal radiotherapy. Finally, a whole new field of application of PET in molecular biology using new radiopharmaceutics is in development. FDG, with its possibility to study tumor glucose metabolism, has paved the way for PET in clinical oncology. It is hoped that PET examinations with new molecular tracers will allow ever better specificity and become sufficiently reliable and manageable to evaluate receptors, transport proteins, and intracellular enzymes so that very early response monitoring during chemotherapy or radiotherapy, evaluation of novel molecular-targeted lung cancer therapies, or even gene therapy becomes possible. New tracers that have showed their promise in early clinical studies include 18F-fluorothymidine (a proliferation marker that might give better specificity in the assessment of solitary pulmonary nodules or better accuracy in the evaluation of early response), (99m)Tc-Annexin V (Apomate; an apoptosis-imaging agent that could be correlated with overall and progression-free survival in phase I data), or 18F-fluoromisonidazole (which can be used to quantify regional hypoxia in human tumors with PET).