Lung Cancer, An Issue of PET Clinics - Fletcher.pdf

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Lung Cancer, An Issue of PET Clinics - Fletcher.pdf

Lung Cancer, An Issue of PET Clinics - Fletcher.pdf

格式: pdf 页数: 66 文件大小: 2MB
Lung Cancer, An Issue of PET Clinics - Fletcher.pdf P O S I T R O N E M I S S I O N T O M O G R A P H Y PET Clin 1 (2006) ix–x ixPreface James W. Fletcher, MD Guest Editor James W. Fletcher, MD Division of Nuclear Medicine PET Imaging Center Department of Radiology Indiana University School of Medicine Indiana/Purdue University at Indianapolis University Hospital, Room 0655 550 North University Boulevard Indianapolis, IN 46234, USA E-mail address: jwfletch@iupui.eduPositron emission tomography (PET) is now an important cancer-imaging tool, both for diagnosis and staging, as well as offering prognostic in- formation based on response. PET is the gold standard in the evaluation of an indeterminate solitary pulmonary nodule (SPN) or mass, where PET has proved to be significantly more accurate than computed tomography (CT). PET is signifi- cantly more accurate than CT in the evaluation of metastatic spread to locoregional lymph nodes, so that invasive surgical staging may be omitted in many patients with negative mediastinal PET images. Invasive surgical staging remains mandatory in patients with positive mediastinal PET images because of the possibility of false-positive findings owing to inflammatory nodes or granulomatous disorders. PET is a useful adjunct to conventional imaging in the search for metastatic spread. This may be due to the finding of unexpected metastatic lesions or the exclusion of malignancy in lesions that are equivocal on standard imaging. However, at this time, PET does not replace conventional imaging.1556-8598/07/$ – see front matter ª 2007 Elsevier Inc. All right pet.theclinics.comThe evaluation of SPNs was one of the first Centers for Medicare and Medicaid Services approved and widespread Fluorodeoxyglucose- PET oncologic applications. Collectively, more has been published on the use of FDG-PET in evaluation of SPNs and staging of non–small-cell lung cancer (NSCLC) than any other clinical PET application. The evaluation of lung cancer probably represents the most common application of FDG- PET in most clinical departments. Lung cancer is currently the leading cause of cancer deaths among both men and women in the United States, with statistical estimates of 169,400 new diagnoses and 154,900 cancer deaths in 2002. In editing this issue of Positron Emission Tomogra- phy Clinics on lung cancer, I have endeavored to incorporate the perspectives of a number of special- ists who are typically involved in the diagnosis, treatment, and management of patients with lung cancer. Contributions are presented from the perspective of the pulmonary radiologist, the interventional radiologist, the respiratory medical oncologist, the radiation therapy oncologist, ands reserved. doi:10.1016/j.cpet.2007.01.001 Prefacexnuclear medicine/PET specialists. Two articles were written by individuals who have special additional expertise and experience in medical economics and cost–benefit, cost-effectiveness analysis (CEA). The article on the diagnosis of lung cancer from the perspective of the pulmonary radiologist is presented by Drs. Teague and Conces. This article is a superb summary of the radiographic features of lung cancer that is very well illustrated with excellent examples of the radiographic features of both benign and malignant nodules and masses. The roles of transthoracic needle biopsy and bronchoscopic biopsy are also discussed. In their article on staging of lung cancer, Drs. Wynants et al. provide an excellent overview of lung cancer staging as well as detailed information on the N-, T-, and M-factors. They also discuss the impact of FDG-PET in the workup of lung cancer, with emphasis on the valuable role of PET in guidance for invasive procedures. An example of the beneficial impact of PET on overall stage and patient management is the substantial reduction in the number of futile thoracotomies observed when PET is incorporated into the workup. Dr. Michael Mac Manus provides an entire article devoted to the role of PET in radiation therapy planning. He presents a detailed summary and review of the role of imaging in radiation oncology, with special emphasis on PET and PET/CT. The results of the use of PET for selection of patients for radical radiation therapy and the impact of PET on patient outcomes are also discussed. It is clear that PET is transforming the way that radiation oncol- ogists approach the treatment of lung cancer. The use of PET for selection of patients for radical therapy alone has already improved the apparent success rate with radiation therapy. In the first article on the cost-effectiveness of FDG-PET, Drs. Hoekstra et al. detail their experience with the introduction of PET in the Netherlands, together with the design of parallel cost-effective- ness studies from their institution and other hospitals in their region. Techniques and designs for decision modeling and clinical value studies are described in detail, along with the intrinsic prob- lems of implementation. The authors define reason-able outcome measures for randomized clinical trials (RCTs) that employ diagnostic imaging procedures, ie, the extent to which appropriate therapy is applied as a result of the diagnostic intervention. The results of their PET in lung cancer staging (PLUS) multicenter study are presented as an example of a well-designed RCT with FDG-PET as the imaging modality, where the use of PET resulted in a 50% reduction in futile thoracotomies. A more specific example of cost-effectiveness studies in imaging is presented in an article on the cost-effectiveness of PET for characterizing SPNs by Dr. Michael Gould. This article introduces the topic of CEA with a very clear and understand- able discussion of CEA compared with other types of economic evaluations. The author also provides the reader with a concise guide to interpreting the results of a CEA. The results of several CEA studies on FDG- PET in SPN are reviewed, with comments and critiques regarding strengths and weaknesses of study design. As the author points out, payers will likely require evidence of cost-effectiveness when making future coverage decisions as health care costs continue to increase in this country. An important treatise on the accuracy of dual- modality FDG-PET/CT imaging in the staging of NSCLC compared with FDG-PET alone, as well as FDG-PET and CT read side by side, is presented in the article on anato-metabolic imaging by Drs. Freudenberg et al. These authors discuss the value and limitations of software versus hardware imaging fusion in FDG-PET/CT. The results of several recent large studies indicate a definite advantage for hardware dual-modality imaging fusion, inasmuch as the combined modality is able to detect significantly more lesions and has a larger impact on change/modification of patient manage- ment. As a bonus, the article provides the reader with an excellent summary of features designed to optimize FDG-PET/CT imaging protocols. Many thanks are extended to all of the authors who contributed to this issue of Positron Emission Tomography Clinics for their diligence and support. A variation on the ancient Chinese proverb/curse is offered to all: ‘‘May we continue to live in interesting times.’’ P O S I T R O N E M I S S I O N T O M O G R A P H Y PET Clin 1 (2006) 289–300 289Diagnosis of Lung Cancer: Perspective of a Pulmonary Radiologist Shawn D. Teague, MD*, Dewey J. Conces, Jr, MD - Clinical - Radiography - Location - Number - Size - Calcification - Dynamic enhancement - Attenuation - Morphology - Margin - Cavitation - Growth rate - Bayesian analysis - Follow-up - Tissue diagnosis - ReferencesThe solitary pulmonary nodule (SPN), a common incidental finding on routine radiographic imaging, is defined as a focal, oval, or round area of increased density in the lung that is less than 3 cm in diame- ter. In fact, there are an estimated 150,000 SPNs de- tected annually in the United States [1], and a single pulmonary nodule is detected on up to 0.2% of all chest radiographs [2]. The majority of SPNs are due to benign diseases such as hamartomas or granulo- mas [3,4]. A significant number, however, are ma- lignant (up to 40% of single pulmonary nodules) [5]. Because the care of lung cancer is dependent on diagnosis at an early stage, it is important to evaluate nodules as expeditiously as possible. The evaluation of an SPN involves the use of a variety of modalities, because up to 25% to 39% of malig- nant nodules are inaccurately classified as benign after radiologic assessment of size, margin, contour, and internal characteristics [6]. In this article, the authors address the assessment of SPN radiograph- ically for benign or malignant characteristics.1556-8598/07/$ – see front matter ª 2007 Elsevier Inc. All righ pet.theclinics.comClinical Patient history plays a significant role in the evalu- ation of SPNs. A patient under 30 years old has a very low risk of an SPN being malignant unless the patient has a known extrathoracic malignancy. As the age of the patient increases, the likelihood of malignancy tends to increase. There are other risk factors that significantly in- crease the likelihood of malignancy, such as a his- tory of smoking, asbestos exposure, coal mining occupation, fibrosis, and known extrathoracic ma- lignancy. In a patient who has a history of smoking, the incidence of lung cancer no longer increases once the patient ceases to smoke; however, the inci- dence is never equal to that of an individual who has never smoked. Presenting symptoms can be an important factor from a clinical standpoint in determining the likelihood of malignancy. In a pa- tient who has suspected infection, it is reasonable to pursue a less aggressive course and obtainDepartment of Radiology, Indiana University School of Medicine, 550 North University Boulevard, Room 0279, University Hospital, Indianapolis, IN 46250, USA * Corresponding author. E-mail address: sdteague@iupui.edu (S.D. Teague).ts reserved. doi:10.1016/j.cpet.2006.09.004 Teague & Conces290short-term follow-up radiographic imaging to document improvement in the nodule. In certain extrathoracic primary malignancies, the risk of an SPN being a metastases is much greater (such as melanoma, sarcoma, or testicular carcinoma) com- pared with other malignancies (such as head and neck squamous cell carcinoma) in which an SPN is much more likely to be a primary lung malignancy [7]. Radiography The first imaging usually performed is the plain chest radiograph. An SPN, however, is seldom noted on a chest radiograph before it reaches 9 mm in diameter [8]. The false-negative rate for primary lung cancer on routine radiographic exam- inations has been reported to be 30% to 40% [9]. When evaluating plain radiographs, it is important to obtain prior examinations for comparison. A multicenter trial from the Mayo Clinic indicated that nearly 90% of peripheral lung cancers could be seen retrospectively on prior radiographic exam- ination that were reported as negative at the time of initial interpretation [10]. Missed or overlooked lung nodules tend to occur in the lung apices, peri- hilar regions, and behind the heart and diaphragm on the frontal view. On the lateral view, lesions are typically missed when located posteriorly over the spine or anteriorly over the heart [11,12]. Some lesions can be determined as benign on a plain radiograph; however, most lesions will re- quire further evaluation. If there is a question that the density seen on a chest radiograph represents a real nodule, chest fluoroscopy can be performed. Fluoroscopy can be used to determine if the nodule is real and not just an overlap of other soft tissues resulting in a ‘‘pseudonodule.’’ Up to 20% of sus- pected nodules are actually mimics of other entities such as rib fractures, skin lesions, or combined areas of soft tissue attenuation [1]. Low kilovolts peak chest radiographs can be obtained to deter- mine if calcification is present. If these two examinations are not performed or are nonconclusive, the next diagnostic imaging test to consider is a thoracic CT examination. This examination cannot only define the morphologic characteristics of the nodule, but excels at identifica- tion of calcification within the nodule. CT is 10 to 20 times more sensitive for calcification when com- pared with traditional tomography, and 22% to 36% of nodules not obviously calcified on tomo- grams are shown to contain calcification on CT examination [13–15]. CT also allows quantitative assessment of calcification present in the nodule [15–18]. If the calcification is visible on thin-section CT images, the Hounsfield measurement will usually have values of 400 H or greater. How- ever, calcium can be present and not grossly visible. Therefore, if the measurement is 200 H or greater, then the nodule can be declared as containing calcification [19]. CT can also further characterize the features of the nodule, including nodule mar- gin, tissue composition, number and size of lesions, and growth rate (when serial examinations are available). However, nodules can also be missed on CT scans. Swensen and colleagues [20] reported that of nodules that were missed on previous screening CT examinations, 62% were less than 4 mm in diameter, 37% were between 4 mm and 7 mm, and 2% were 8 mm to 20 mm in diameter. Ko and colleagues [21] reported that ground glass nodules were less frequently detected (65%) compared with solid nodules (83%) and there was a decreased sensitivity for detecting central compared with peripheral nodules (61% versus 80%). Finally, they also reported nodules adjacent to the pleura were better detected (84%) versus those not in contact with the pleural surface (75%). Thinner sections, multiplanar reformats (espe- cially MIPs), and cine viewing have all been shown to improve nodule detection [22–25]. CAD systems are being developed to help improve the nodule detection on both plain radiography and CT exam- inations. The efficiency of CAD systems has been reported to be between 38% and 95% [21]. The CT evaluation of a patient who has proven or suspected SPN should start with an examination without use of intravenous contrast through the entire chest. This serves to locate the nodule for further evaluation with thin sections, and also to document other abnormalities that include effusions, lymphadenopathy, or additional nod- ules. If there is only an SPN, then thin-section (1–3 mm) CT examination is suggested to fully characterize an SPN. Unless characteristics such as central calcification or fat are noted, the nodule will still remain indeterminate. In this situation, the nodule can be further evaluated with dynamic contrast-enhanced CT scan if it meets the appropri- ate criteria, or followed up over time with serial CT scans for growth assessment. Those nodules with characteristics suggesting malignancy can be further evaluated with a radiographic or surgical biopsy procedure. With multidetector CT scanners, the thoracic scans can be performed with isotropic images retro- spectively reconstructed from the raw data of rou- tine helical scans provided the thinnest detector configuration is used for the initial routine scan. This somewhat eliminates the need to obtain addi- tional thin sections specifically through the nodule in question. These thin sections are also useful for ...