FDG PET of pleural effusions in patients with non-small cell lung cancer

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.

A prospective study of PET/CT in initial staging of small-cell lung cancer: comparison with CT, bone scintigraphy and bone marrow analysis

BACKGROUND

Small-cell lung cancer (SCLC) accounts for 15%-20% of all lung cancer cases. Accurate and fast staging is mandatory when choosing treatment, but current staging procedures are time consuming and lack sensitivity.

PATIENTS AND METHODS

A prospective study was designed to examine the role of combined positron emission tomography/computed tomography (PET/CT) compared with standard staging (CT, bone scintigraphy and immunocytochemical assessment of bone marrow biopsy) of patients with SCLC. Thirty-four consecutive patients were included. Twenty-nine patients received initial PET/CT.

RESULTS

PET/CT caused change of stage in 5/29 (17%). Excluding patients with unconfirmed findings or pleural effusion, the sensitivity for accurate staging of patients with extensive disease was the following: for standard staging 79%, PET 93% and PET/CT 93%. Specificity was 100%, 83% and 100%, respectively.

CONCLUSION

The results from this first study on PET/CT in SCLC indicates that PET/CT can simplify and perhaps even improve the accuracy of the current staging procedure in SCLC. A larger clinical trial, preferably with consequent histological confirmation in case of discordance, however, is warranted.

PET/CT Imaging of Lung Cancer

Fluoro-deoxyglucose positron emission tomography (PET) imaging has a diagnostic and prognostic value in the initial staging, restaging, and surveillance of non-small-cell lung cancer (NSCLC). When used in conjunction with conventional radiologic imaging, PET imaging has been shown to result in significant changes in clinical management of NSCLC. Specifically, baseline PET imaging can improve initial staging and guide surgical and radiotherapy planning, whereas repeat PET imaging after the initiation of chemoradiotherapy can predict tumor response and help tailor therapy. After the end of definitive treatment, PET has greater diagnostic accuracy than other imaging modalities for the detection of tumor recurrence. The recent development of fused PET/CT imaging has improved the radiologic evaluation of NSCLC patients by combining metabolic and anatomic imaging; however, this has resulted in more complexity in the image interpretation. It is important for the interpreting physician to understand the role PET/CT plays in the staging, assessment of treatment, and follow-up after therapy in the multidisciplinary management of patients with NSCLC.

Advances in image-guided radiation therapy—the role of PET-CT

In the era of image-guided radiation therapy (IGRT), the greatest challenge remains target delineation, as the opportunity to maximize cures while simultaneously decreasing radiation dose to the surrounding normal tissues is to be realized. Over the last 2 decades, technological advances in radiographic imaging, biochemistry, and molecular biology have played an increasing role in radiation treatment planning, delivery, and evaluation of response. Previously, fluoroscopy formed the basis of radiation treatment planning. Beginning in the late 1980s, computed tomography (CT) has become the basis for modern radiation treatment planning and delivery, coincident with the rise of 3-dimensional conformal radiation therapy (3DCRT). Additionally, multi-modality anatomic imaging registration was the solution pursued to augment delineation of tumors and surrounding structures on CT-based treatment planning. Although these imaging modalities provide the customary anatomic details necessary for radiation treatment planning, they have limitations, including difficulty with identification of small tumor deposits, tumor extension, and distinction from scar tissues. To overcome these limitations, PET and, more recently, PET-CT have been innovative regarding the extent of disease appraisal, target delineation in the treatment planning, and assessment of therapy response. We review the role of functional imaging in IGRT as it reassures transformations on the field of radiation oncology. As we move toward the era of IGRT, the use of multi-modality imaging fusion, and the introduction of more sensitive and specific PET-CT tracers may further assist target definition. Furthermore, the potential to predict early outcome or even detect early recurrence of tumor, may allow for the tailoring of intervention in cancer patients. The convergence of a biological target volume, and perhaps multi-tracer tumor, molecular, and genetic profile tumors will probably be vital in cancer treatment selection. Nevertheless, prospective clinical experience with outcome is encouraged and needs to be expanded to entirely exploit the benefits of the IGRT.

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 the Patient with Non–Small Cell Lung Cancer

Lung cancer is the most common type of cancer and is the leading cause of cancer deaths in the United States for both men and women. Even though the 5-year survival rate of patients with lung cancer remains dismal at 14% for all cancer stages, treatments are improving and newer agents for lung cancer appear promising. Therefore, an accurate assessment of the extent of disease is critical to determine whether the patient is treated with surgical resection, radiation therapy, chemotherapy, or a combination of these modalities. Radiologic imaging plays an important role in the staging evaluation of the patient; however, radiologists need to be aware that there are also important differences in what each specialist needs from imaging to provide appropriate treatment. This article reviews the role of imaging in patients with non-small cell lung cancer, with an emphasis on the radiologic imaging findings relevant for each specialty.

Imaging of non-small cell lung cancer

Radiologic evaluation is an important component of the clinical staging evaluation of lung cancer and can greatly influence whether the patient is treated with surgical resection, radiation therapy, chemotherapy, or a combination of these modalities. In addition to staging, the radiologic evaluation of the patient undergoing treatment and subsequent follow-up is important to the clinician for assessing treatment effects and complications. This article discusses the imaging of patients with non-small cell lung cancer and its use in management of these patients.

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.

Non-small cell lung cancer: evaluation of pleural abnormalities on CT scans with 18F FDG PET

PURPOSE

To evaluate the accuracy of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in differentiation of pleural malignancy and cancer-unrelated pleural disease in patients with non-small cell lung cancer (NSCLC) and pleural abnormalities at computed tomography (CT).

MATERIALS AND METHODS

In 92 patients, pleural abnormalities were detected at contrast material-enhanced thoracic CT, which was performed for newly diagnosed NSCLC (n = 41) or restaging (n = 51). CT findings were negative for pleural malignancy when pleural effusion with attenuation of 10 HU or less and/or rib fractures with no evidence of pathologic fracture were present; findings were indeterminate when pleural effusion with attenuation greater than 10 HU and/or solid pleural abnormalities without osseous destruction of the chest wall were present; and findings were positive if any osseous destruction of the chest wall adjacent to a pleural mass was present. All patients underwent FDG PET. Findings were negative for pleural malignancy if pleural activity was absent, equal to, or less than mediastinal background activity; findings were positive if pleural activity was higher than mediastinal background activity. Reading of CT and FDG PET scans was first performed separately and then was combined. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPP), and accuracy were calculated for CT and FDG PET separately and for CT and FDG PET combined, with cytologic and/or histologic analysis as standard of reference.

RESULTS

In detection of pleural malignancies, CT findings were indeterminate in 65 (71%) patients and true-negative in 27 (29%). Respective sensitivity, specificity, PPV, NPV, and accuracy of FDG PET in detection of pleural malignancies were 100%, 71%, 63%, 100%, and 80%; and those of CT and FDG PET combined, 100%, 76%, 67%, 100%, and 84%.

CONCLUSION

Findings suggest that a negative FDG PET scan for indeterminate pleural abnormalities at CT indicates a benign character, while positive findings on an FDG PET scan are sensitive for malignancy.

Clinical applications of PET in oncology

Positron emission tomography (PET) provides metabolic information that has been documented to be useful in patient care. The properties of positron decay permit accurate imaging of the distribution of positron-emitting radiopharmaceuticals. The wide array of positron-emitting radiopharmaceuticals has been used to characterize multiple physiologic and pathologic states. PET is used for characterizing brain disorders such as Alzheimer disease and epilepsy and cardiac disorders such as coronary artery disease and myocardial viability. The neurologic and cardiac applications of PET are not covered in this review. The major utilization of PET clinically is in oncology and consists of imaging the distribution of fluorine 18 fluorodeoxyglucose (FDG). FDG, an analogue of glucose, accumulates in most tumors in a greater amount than it does in normal tissue. FDG PET is being used in diagnosis and follow-up of several malignancies, and the list of articles supporting its use continues to grow. In this review, the physics and instrumentation aspects of PET are described. Many of the clinical applications in oncology are mature and readily covered by third-party payers. Other applications are being used clinically but have not been as carefully evaluated in the literature, and these applications may not be covered by third-party payers. The developing applications of PET are included in this review.

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).

PET scan in the staging of non-small cell lung cancer

Imaging techniques play an essential role in the diagnosis, staging, and follow-up of patients with lung cancer. Positron emission tomography (PET) has become an important innovation in lung cancer imaging. In this report, a comprehensive overview is given of the important number of prospective performance studies, looking at the value of PET in locoregional and distant staging of NSCLC, and at its potential impact on patient management. In the assessment of locoregional lymph node spread, PET has a high negative predictive value in the exclusion of N2 or N3 disease, so that mediastinoscopy can be omitted in most patients with negative mediastinal PET-images. False negative mediastinal PET findings may occur in patients with minimal N2 disease. Because of possible false positive findings in patients with inflammatory nodes or granulomatous disorders, confirmation and lymph node mapping by mediastinoscopy remains mandatory in these situations. In the extrathoracic staging, PET is a useful adjunct to conventional imaging, because it is able to detect unexpected metastatic lesions. An isolated positive finding that determines the possibility for radical treatment requires pathological verification, because of the possibility of a false positive result. PET is also able to exclude malignancy in equivocal lesions, but caution is needed in case of small lesions. There are currently insufficient data to state that PET could replace standard imaging. The use of PET as described in the performance studies, now undergoes further validation in large-scale randomised patient outcome studies. In the meanwhile, a current recommendation for the use of PET in contemporary lung cancer staging is provided.

Staging of recurrent and advanced lung cancer with 18F-FDG PET in a coincidence technique (hybrid PET)

The aim of this study was to evaluate [18F]fluorodeoxyglucose ( F-FDG) imaging of recurrent or inoperable lung cancer using a hybrid positron emission tomography (PET) device of the third generation. Examinations were compared with the results of conventional staging. Thirty-six patients suffering from recurrent or primarily inoperable lung cancer (29 men, seven women; age 64.8+/-12.0 years) were examined using hybrid PET (Marconi Axis gamma-PET ) 60 min after injection of 370 MBq F-FDG. The data obtained were reconstructed iteratively. All patients received a computed tomography (CT) scan using either the spiral or multislice technique. All lesions suspicious for primary or recurrent tumour were verified by biopsy; mediastinal lymph nodes were considered as malignant, when positive histology or a small axis diameter of greater than 1 cm measured with CT in addition to progression of clinical course was found. Distant metastases were diagnosed by CT and bone scintigraphy. Using hybrid PET all lesions showed a focally elevated glucose metabolism. Lymph node involvement of the ipsilateral peribronchial and hilar station (N1) was identified in 24/26 cases (92%), in 26/29 cases (90%) of ipsilateral central manifestation (N2) and in 11/13 (85%) cases of central contralateral or supraclavicular lymphatic infestation (N3). Pulmonary spread in hybrid PET was found in 4/8 cases (50%), whereas mainly lung metastases with a diameter of 1.5 cm and smaller were missed. Pleural involvement diagnosed by CT was verified in 4/5 patients. All four patients with bony metastases in conventional staging also presented with positive findings in hybrid PET (8/9 lesions). Concordance with conventional staging was found in 28/36 of patients (78%). In 4/36 patients (11%) unknown sites of tumour were detected leading to therapeutic consequences in three patients after radiological confirmation. Hybrid PET would have led to an understaging in four cases (11%), resulting theoretically in inefficient treatment in two patients. Hybrid PET for F-FDG imaging in the staging of recurrent or primarily inoperable lung cancer supplied equal (78%) or more information (11%) compared to conventional staging procedures. Using the information of hybrid PET alone, 11% of the patients would have been understaged. We conclude that hybrid PET has the potential for use as an additional staging tool in this subgroup of patients, providing supplementary information compared to conventional staging modalities.

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

STUDY OBJECTIVES

The goals of this study were to determine the sensitivity, specificity, and predictive accuracy of F-18 fluorodeoxyglucose positron emission tomography (PET-FDG) imaging in detecting metastatic disease involvement of pleura and/or presence of malignant pleural effusion in patients with proven lung cancer. We wanted to compare efficacy of PET-FDG imaging to CT scanning in differentiating benign pleural effusion from malignant effusion and/or pleural involvement in patients with lung cancer.

METHODS

We studied 35 patients with biopsy-proven lung cancer and abnormal findings on CT scanning for presence of pleural effusion (n = 34) and/or pleural thickening or nodular involvement (n = 4). The results of positron emission tomography and CT scanning were compared to pleural cytology (n = 31), histologic findings of pleural biopsy (n = 3), and/or clinical follow-up (n = 3) for at least 1 year for presence or absence of malignant pleural effusion.

RESULTS

PET-FDG imaging correctly detected the presence of malignant pleural effusion and malignant pleural involvement in 16 of 18 patients and excluded malignant effusion or pleural metastatic involvement in 16 of 17 patients (sensitivity, specificity, and accuracy of 88.8%, 94.1%, and 91.4% respectively).

CONCLUSION

PET-FDG imaging is a highly accurate and reliable noninvasive test to differentiate malignant from benign pleural effusion and/or pleural involvement in patients with lung cancer and findings of suspected malignant pleural effusion on CT scanning.

Positron emission tomography imaging in nonmalignant thoracic disorders

The role of the fluorodeoxyglucose (FDG) technique positron emission tomography (PET) is well established in the management of patients with lung cancer. Increasingly, it is becoming evident that FDG-PET can be effectively employed to diagnose a variety of benign pulmonary disorders. Knowledge of such applications further expands the domain of this powerful modality and further improves the ability to differentiate benign from malignant diseases of the chest. We describe pertinent technical factors that substantially contribute to optimal imaging of the thoracic structures. Particularly, the complementary role of attenuation correction (AC) to that of non-AC images is emphasized. We further outline the need for and the state of the art for co-registration of PET and anatomic images for diagnostic and therapeutic purposes. We then review patterns of physiologic uptake of FDG in thoracic structures, including the lung, the heart, the aorta and large arteries, esophagus, thymus, trachea, thoracic muscles, bone marrow, and joints and alterations following radiation therapy to the thorax. A great deal of information is provided with regard to differentiating benign from malignant nodules and in particular, we emphasize the role of dual time point imaging and partial volume correction for accurate assessment of such lesions. Following a brief review of the diagnostic issues related to the assessment of mediastinal adenopathies, the role of FDG-PET imaging in environment-induced lung diseases, including pneumoconiosis, smoking, and asthma are described. A large body of information is provided about the role of this technology in the management of patients with suspected infection and inflammation of the lungs such as acquired immunodeficiency syndrome, fever of unknown origin, sarcoidosis, chronic granulomatous disease and monitoring the disease process and response to therapy. Finally, the value of FDG-PET in differentiating benign from malignant diseases of the pleura including asbestosis-related disorders is described at the conclusion of this comprehensive review.

Positron emission tomography in lung cancer

Carcinoma of the lung is one of the most frequent malignancies and a major cause of mortality. The use of positron emission tomography (PET) has been extensively investigated in patients with carcinoma of the lung and has established clinical utility and cost-effectiveness in characterization of solitary pulmonary nodules and preoperative staging of carcinoma of the lung. Evolving applications in carcinoma of the lung include detection of recurrence, assessment of treatment response, radiotherapy planning, and prognosis. In addition, there is developing interest in combined anatomic/metabolic imaging and new tracer techniques, in particular gene expression imaging. This review aims to present existing data supporting the use of PET in carcinoma of the lung and to explore the evolving indications and future prospects of PET and lung cancer.

Imaging of thoracic occupational and environmental malignancies

The imaging features of occupational lung cancer are similar to those of nonoccupational cancer. Occupational lung cancer in patients with asbestos exposure must be differentiated from mimics such as round atelectasis and fissural pleural plaques. Mesothelioma remains a largely incurable tumor, though treatment options are expanding. CT, MRI, and PET scanning may all have complementary roles in staging mesothelioma.

Positron emission tomography (PET) and combined imaging modalities for staging lung cancer

FDG PET in its current form supplements but does not yet replace other noninvasive imaging modalities for the evaluation and staging of the patient with NSCLC. Clinicians await further data from well-designed clinical trials to help integrate FDG PET into current clinical practice. Looking forward, sophisticated radiolabeling techniques promise to improve both the diagnostic accuracy of PET and our ability to deliver targeted cancer therapy to patients.