Invited review--Off-site PET imaging programs: challenges and opportunities.

Veterinarians are gaining interest in and access to Position Emission Tomography (PET and PET/CT) imaging for both clinical and research applications. This manuscript provides an overview of how veterinarians may approach the use of off-site PET and PET/CT scanners already in use for human medical imaging in order to gain access to this technology without direct investment in costly equipment and infrastructure. An overview of general procedures, animal transport, and radiation safety considerations is offered along with references to key regulatory statutes that may apply to the operation of PET imaging facilities in individual states.

[ECONOMIC EFFICIENCY TECHNOLOGIES DIAGNOSIS OF ISCHEMIC HEART DISEASE BY MAHNITOTOKARDIOHRAFIYI].

The article is devoted to clinical--economic analysis of modern diagnostic technology--magnetocardiography by analyzing the "cost-effectiveness". Economic effectiveness of diagnosis of coronary artery disease using magnetocardiography in terms of cost/effectivness is shown. The economicaly optimal sequence of several noninvasive methods for diagnosis of coronary artery disease is defined.

Significance of radiation dose in medical imaging.

Publicized cases of errant high radiation exposure delivered to patients undergoing diagnostic imaging have led to heightened awareness and scrutiny of the costs and benefits of imaging by physicians, the public, and policymakers.The statistical risks associated with the ever-increasing utilization of modalities employing damaging ionizing radiation across the population are compounded by the development of the latest generation of devices, which are capable of delivering greater radiation doses than their predecessors for comparable diagnostic applications.This article reviews the fundamental concepts and risks of medical radiation exposure, trends in imaging utilization, and the role of radiologists and their physician colleagues in managing and appropriately utilizing imaging for patient diagnosis.

Recommendations for optimal use of imaging studies to clinically stage mediastinal lymph nodes in non-small-cell lung cancer patients.

Appropriate clinical staging of mediastinal lymph nodes in non-small-cell lung cancer (NSCLC) patients has important therapeutic and prognostic implications. Because of the wide variations in practice patterns among community and academic physicians, we reviewed the literature so that we could provide evidence-based recommendations on the use of imaging studies in the pretreatment clinical staging of NSCLC patients. We concluded that the most sensitive and accurate method of noninvasive mediastinal nodal staging is a positron emission tomography/computed tomography fusion scan; we believe this tool should be a component of clinical staging of all NSCLC patients. Given insufficient sensitivity with currently available imaging studies, mediastinal nodal staging should also include histologic evaluation.

Structural neuroimaging in psychosis: a systematic review and economic evaluation.

OBJECTIVES: To establish the clinical effectiveness and cost-effectiveness of structural neuroimaging [structural magnetic resonance imaging (MRI) or computed tomography (CT) scanning] for all patients with psychosis, particularly a first episode of psychosis, relative to the current UK practice of selective screening only where it is clinically indicated. DATA SOURCES: Major electronic databases were searched from inception to November 2006. REVIEW METHODS: A systematic review of studies reporting the additional diagnostic benefit of structural MRI, CT or combinations of these in patients with psychosis was conducted. The economic assessment consisted of a systematic review of economic evaluations and the development of a threshold analysis to predict the gain in quality-adjusted life-years (QALYs) required to make neuroimaging cost-effective at commonly accepted threshold levels (20,000 pounds and 30,000 pounds per QALY). Sensitivity analyses of several parameters including prevalence of psychosis were performed. RESULTS: The systematic review included 24 studies of a diagnostic before-after type of design evaluating the clinical benefit of CT, structural MRI or combinations in treatment-naive, first-episode or unspecified psychotic patients, including one in schizophrenia patients resistant to treatment. Also included was a review of published case reports of misidentification syndromes. Almost all evidence was in patients aged less than 65 years. In most studies, structural neuroimaging identified very little that would influence patient management that was not suspected based on a medical history and/or physical examination and there were more incidental findings. In the four MRI studies, approximately 5% of patients had findings that would influence clinical management, whereas in the CT studies, approximately 0.5% of patients had these findings. The review of misidentification syndromes found that 25% of CT scans affected clinical management, but this may have been a selected and therefore unrepresentative sample. A threshold analysis with a 1-year time horizon was undertaken. This combined the incremental cost of routine scanning with a threshold cost per QALY value of 20,000 pounds and 30,000 pounds to predict the QoL gain required to meet these threshold values. Routine scanning versus selective scanning appears to produce different results for MRI and CT. With MRI scanning the incremental cost is positive, ranging from 37 pounds to 150 pounds; however, when scanning routinely using CT, the result is cost saving, ranging from 7 pounds to 108 pounds with the assumption of a 1% prevalence rate of tumours/cysts or other organic causes amenable to treatment. This means that for the intervention to be viewed as cost-effective, the QALY gain necessary for MRI scanning is 0.002-0.007 and with CT scanning the QALY loss that can be tolerated is between 0.0003 and 0.0054 using a 20,000 pounds threshold value. These estimates were subjected to sensitivity analysis. With a 3-month time delay, MRI remains cost-incurring with a small gain in QoL required for the intervention to be cost-effective; routine scanning with CT remains cost-saving. When the sensitivity of CT is varied to 50%, routine scanning is both cost-incurring or cost-saving depending on the scenario. Finally, the results have been shown to be sensitive to the assumed prevalence rate of brain tumours in a psychotic population. CONCLUSIONS: The evidence to date suggests that if screening with structural neuroimaging was implemented in all patients presenting with psychotic symptoms, little would be found to affect clinical management in addition to that suspected by a full clinical history and neurological examination. From an economic perspective, the outcome is not clear. The strategy of neuroimaging for all is either cost-incurring or cost-saving (dependent upon whether MRI or CT is used) if the prevalence of organic causes is around 1%. However, these values are nested within a number of assumptions, and so have to be interpreted with caution. The main research priorities are to monitor the current use of structural neuroimaging in psychosis in the NHS to identify clinical triggers to its current use and subsequent outcomes; to undertake well-conducted diagnostic before-and-after studies on representative populations to determine the clinical utility of structural neuroimaging in this patient group, and to determine whether the most appropriate structural imaging modality in psychosis should be CT or MRI.

The role of imaging in Graves' disease: a cost-effectiveness analysis.

According to many guidelines, scintigraphy remains the first suggested diagnostic procedure in hyperthyroid patients in spite of the widespread availability of ultrasounds. The aim of this study was to evaluate the cost-effectiveness of sonography versus scintigraphy in the management of Graves's disease, and to assess ultrasound features suggesting cancer in detecting thyroid nodules. Among 1470 hyperthyroid patients evaluated in our department from 2002 to 2005, 426 (29%) had Graves' disease: echographic and scintigraphic features were not suggestive of GD in 20/426 (4.8%) and 11/426 (2.6%) patients, respectively (p=0.763), even if one of the two procedures was almost always diagnostic. Ultrasound identified 68/426 (16%) patients with a concomitant solid lesion, while scintigraphy detected only 9/426 (2.1%) "cold" nodules (p<0.001). Thyroid cancer was diagnosed in 30/68 (47.7%) patients. Malignancy presented at ultrasound investigation blurred margins (26.7% versus 15.8%), microcalcifications (33.3% versus 28.9%) and an anteroposterior and transverse diameter ratio>or=1 (73.3% versus 71.1%); more frequently than benign nodules, but this was not statistically significant. The total cost to obtain a diagnosis by ultrasound was euro14645.34 (euro13312.5 for echography+euro1332.84 for scintigraphy in the 29 patients "negative" at echographic evaluation for GD) versus euro19922.71 by scintigraphy (euro19578.96 for scan+euro343.75 for ultrasounds in the 11 patients "negative" at scintigraphy). Our data show no difference in terms of diagnosis between sonography and scintigraphy. Indeed, scintigraphy was less sensitive in detecting nodules (often of malignant nature) than ultrasound, and, moreover, with a consequent increase of the direct cost of nodule management when scintigraphy is the first line procedure. In conclusion, according to our results, we suggest that ultrasounds with color-Doppler evaluation should be performed as first step in all hyperthyroid patients, and that scintigraphic examination should be limited only to the uncommon cases, where physician's observation, laboratory assays and/or ultrasounds are not diagnostic.

The roles of PET and PET/CT in the diagnosis and management of prostate cancer.

2-(18)F-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) imaging in prostate cancer is challenging because glucose utilization in well-differentiated prostate cancer is often lower than in other tumor types. Nonetheless, FDG-PET has a high positive predictive value for untreated metastases in viscera, but not lymph nodes. A positive FDG-PET can provide useful information to aid the clinician's decision on future management in selected patients who have low prostate-specific antigen levels and visceral changes as a result of metastases. On the other hand, FDG-PET is limited in the identification of prostate tumors, as normal urinary excretion of radioisotope can mask pathological uptake. Moreover, there is an overlap in the degree of uptake between prostate cancer, benign prostatic hyperplasia and inflammation. The tracer choice is also important. (11)C-choline has the advantage of reduced urinary excretion, and thus (11)C-choline PET may provide more accurate information on the localization of main primary prostate cancer lesions than MRI or MR spectroscopy. (11)C-choline PET is sensitive and accurate in the preoperative staging of pelvic lymph nodes in prostate cancer. A few studies are available but there were no PET or PET/CT studies with a large number of patients for tissue confirmation of prostate cancer; further investigations are required.

Impact of the Publication of Appropriate Use Criteria on Utilization Rates of Myocardial Perfusion Imaging Studies in Ontario, Canada: A Population-Based Study.

BACKGROUND: Concern regarding overutilization of cardiac imaging has led to the development of appropriate use criteria (AUC). Myocardial perfusion imaging (MPI) is one of the most commonly used cardiac imaging modalities worldwide. Despite multiple iterations of AUC, there is currently no evidence regarding their real-world impact on population-based utilization rates of MPI. Our goal was to assess the impact of the AUC on rates of MPI in Ontario, Canada. We hypothesized that publication of the AUC would be associated with a significant reduction in MPI rates. METHODS AND RESULTS: We conducted a retrospective cohort study of the adult population of Ontario from January 1, 2000, to December 31, 2015. Age- and sex-standardized rates were compared from 4 different periods intersected by 3 published iterations of the AUC. Overall, 3 072 611 MPI scans were performed in Ontario during our study period. The mean monthly rate increased from 14.1/10 000 in the period from January 2000 to October 2005 to 18.2/10 000 between November 2005 and June 2009. After this point in time, there was a reduction in rates, falling to a mean monthly rate of 17.1/10 000 between March 2014 and December 2015. Time series analysis revealed that publication of the 2009 AUC was associated with a significant reduction in MPI rates (P<0.001). This translated into ≈88 849 fewer MPI scans at a cost savings of ≈72 million Canadian dollars. CONCLUSIONS: Our results reflect a potential real-world impact of the 2009 MPI AUC by demonstrating evidence of a significant effect on population-based rates of MPI.

Acquiring new technology and surviving environmental pressures.

CONTEXT: The U.S. health care system faces increased pressures to expand coverage to the elderly, the uninsured and the poor, while maintaining costs and quality of care. Because of the federal budget deficit and continued fiscal uncertainties, resource allocation will become even more scrutinized. OBJECTIVE: How does a health care system allocate limited funds and still provide quality care using innovative technology? METHOD: This article reviews the literature on the acquisition of new technologies from a theoretical perspective, using positron emission tomography (PET) as an example. A unified model, including concepts from the resource dependency theory (RDT) supplemented with organizational survival concepts from the ecological theory, was used to analyze resource acquisition for technological innovation and organizational survival. An attempt was made to evaluate a hospital's profit maximization, recognition as a center of clinical excellence and role as a technological leader of the community with respect to acquisition of PET equipment. CONCLUSION: Organizations acquire new technology for a variety of reasons that can be explained by RDT and ecological theory concepts. In terms of the profit maximization motive, hospitals purchase PET equipment to enhance revenue generation. From the clinical excellence perspective, organizations seek the best available technology to meet the needs of their patients. Finally, hospitals adopt new technology to enhance their image as a technological leader.

Cost-effectiveness of alternative management strategies for patients with solitary pulmonary nodules.

BACKGROUND: Positron emission tomography (PET) with 18-fluorodeoxyglucose (FDG) is a potentially useful but expensive test to diagnose solitary pulmonary nodules. OBJECTIVE: To evaluate the cost-effectiveness of strategies for pulmonary nodule diagnosis and to specifically compare strategies that did and did not include FDG-PET. DESIGN: Decision model. DATA SOURCES: Accuracy and complications of diagnostic tests were estimated by using meta-analysis and literature review. Modeled survival was based on data from a large tumor registry. Cost estimates were derived from Medicare reimbursement and other sources. TARGET POPULATION: All adult patients with a new, noncalcified pulmonary nodule seen on chest radiograph. TIME HORIZON: Patient lifetime. PERSPECTIVE: Societal. INTERVENTION: 40 clinically plausible combinations of 5 diagnostic interventions, including computed tomography, FDG-PET, transthoracic needle biopsy, surgery, and watchful waiting. OUTCOME MEASURES: Costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios. RESULTS OF BASE-CASE ANALYSIS: The cost-effectiveness of strategies depended critically on the pretest probability of malignancy. For patients with low pretest probability (26%), strategies that used FDG-PET selectively when computed tomography results were possibly malignant cost as little as 20 000 dollars per QALY gained. For patients with high pretest probability (79%), strategies that used FDG-PET selectively when computed tomography results were benign cost as little as 16 000 dollars per QALY gained. For patients with intermediate pretest probability (55%), FDG-PET strategies cost more than 220 000 dollars per QALY gained because they were more costly but only marginally more effective than computed tomography-based strategies. RESULTS OF SENSITIVITY ANALYSIS: The choice of strategy also depended on the risk for surgical complications, the probability of nondiagnostic needle biopsy, the sensitivity of computed tomography, and patient preferences for time spent in watchful waiting. In probabilistic sensitivity analysis, FDG-PET strategies were cost saving or cost less than 100 000 dollars per QALY gained in 76.7%, 24.4%, and 99.9% of computer simulations for patients with low, intermediate, and high pretest probability, respectively. CONCLUSIONS: FDG-PET should be used selectively when pretest probability and computed tomography findings are discordant or in patients with intermediate pretest probability who are at high risk for surgical complications. In most other circumstances, computed tomography-based strategies result in similar quality-adjusted life-years and lower costs.

F-18 NaF PET for detection of bone metastases in lung cancer: accuracy, cost-effectiveness, and impact on patient management.

UNLABELLED: As bone metastases might be present in lung cancer despite a normal bone scan, we examined various alternatives prospectively. Positron emission tomography using F-18 sodium fluoride (PET) and single photon emission tomography (SPECT) were more sensitive than a planar bone scan. PET was more accurate with a shorter examination time than SPECT but had higher incremental costs. INTRODUCTION: Previous studies have shown that vertebral bone metastases not seen on planar bone scans may be present on F-18 fluoride positron emission tomography (PET) scan or single photon emission computed tomography (SPECT). The purpose of this study was to measure the accuracy, clinical value and cost-effectiveness of tomographic bone imaging. MATERIALS AND METHODS: A total of 103 patients with initial diagnosis of lung cancer was prospectively examined with planar bone scintigraphy (BS), SPECT of the vertebral column and PET using F-18 sodium fluoride (F-18 PET). Receiver operating characteristic (ROC) curve analysis was used for determination of the diagnostic accuracy. A decision-analysis model and the national charge schedule of the German Hospital Association were used for determination of the cost-effectiveness. RESULTS: Thirteen of 33 patients with bone metastases were false negative on BS, 4 on SPECT, and 2 on F-18 PET. The area under the ROC curve was 0.771 for BS, 0.875 for SPECT, and 0.989 for F-18 PET (p < 0.05). As a result of SPECT and F-18 PET imaging, clinical management was changed in 8 (7.8%) and 10 (9.7%) patients. Compared with BS, the costs per additional correctly diagnosed patient were 1272 Euro with SPECT and 2861 Euro with F-18 PET. The threshold for the costs of F-18 PET being more cost-effective than SPECT was 345 EUR. CONCLUSION: Routine performance of tomographic bone imaging improves the therapeutic strategy because of detection of otherwise missed metastases. F-18 PET is more effective than SPECT but is associated with higher incremental costs.

Hurdles to technology diffusion: what are expectations for PET?

Regulatory and economic hurdles to the introduction and the diffusion of expensive new medical instrumentation have changed substantially over the past decade. The process of diffusion has been slowed by the introduction of new hurdles and by the gradual shift in their relative importance. FDA approval, affirmative coverage decisions, and the setting of appropriate levels of reimbursement greatly influence the diffusion and utilization of major new technologies. Positron emission tomography (PET) is not an exception. This paper examines the mechanics of these hurdles and their impact on the availability of PET.

SPECT versus planar liver scintigraphy: is SPECT worth it?

Five hundred three planar and SPECT hepatic studies were reviewed separately by two experienced observers looking for focal disease. An equivocal reading meant referral to ultrasound or computed tomography (US/CT). The increase in correct readings and decrease in US/CT referrals per 100 positive and per 100 negative SPECT readings were calculated, then the increase in correct readings and decrease in US/CT referrals for various positive rates of liver involvement determined. At our institution, the overall positive rate is approximately 13% yielding 1.1 and 0.83 more correct readings and 1.8 and 2.0 fewer US/CT referrals per 100 cases for each reader, respectively; a marginal benefit for SPECT over planar scintigraphy.

Evaluating early dementia with and without assessment of regional cerebral metabolism by PET: a comparison of predicted costs and benefits.

UNLABELLED: Evaluating dementia in patients with early symptoms of cognitive decline is clinically challenging. Growing evidence indicates that appropriate incorporation of PET into the clinical work-up can improve diagnostic and prognostic accuracy with respect to Alzheimer's disease (AD), the most common cause of dementia in the geriatric population. The precise diagnostic role of PET and its economic impact in this context, however, have not been systematically examined previously. METHODS: We compared the relative value of 2 strategies for assessing whether early AD is responsible for cognitive symptoms in geriatric patients: (a) a conventional approach, based largely on establishing clinical criteria for the presence of dementia and excluding non-AD etiologies that could contribute to the patient's symptoms, and (b) a proposed approach using PET to examine regional cerebral metabolism and look for characteristic patterns of abnormal metabolism. The total costs (measured in dollars) and benefits (measured in number of accurate diagnoses) of diagnostic testing and clinical outcomes accruing to each strategy were calculated using formalized tools of decision analysis. The primary outcome measure by which the strategies were compared was the ratio of costs to benefits obtained following each approach. RESULTS: Following the proposed approach led to improved accuracy in identifying early AD, without adding to the overall costs of diagnosis and treatment ($3,433 vs. $3,564 per patient approached by the proposed or conventional algorithm, respectively). The strategy making use of PET was associated with a reduced rate of false-negative and false-positive findings compared with the conventional approach (3.1% vs. 8.2% and 12.0% vs. 23.0%, respectively, at a prevalence of 51.6% in the studied symptomatic population) and a cost savings of $1,138 per correct diagnosis rendered ($4,047 vs. $5,185). The lower cost per unit benefit for the proposed strategy was maintained over a wide range of tested values for variables of sensitivity, specificity, costs of PET and long-term care, and varying approaches to the use of structural neuroimaging. CONCLUSION: Appropriate use of PET for evaluating early dementia in geriatric patients can add valuable information to the clinical work-up, without adding to the overall costs of evaluation and management, resulting in a greater number of patients being accurately diagnosed for the same level of financial expenditure. Thus, the opportunity exists for diminishing the morbidity of dementia economically, with earlier institution of more appropriate management in evaluated patients.

Comparison of dual-head coincidence PET versus ring PET in tumor patients.

UNLABELLED: This study compared the multiring detector (Ring-PET) and the dual-head coincidence imaging system (DH-PET) for staging/ restaging neoplastic patients before or after surgery or radiochemotherapy. METHODS: Seventy patients with suspected tumor recurrence or metastatic dissemination received an intravenous dose of 18F-fluorodeoxyglucose (FDG) under overnight fasting and were studied in sequence with a dedicated positron emission tomograph with Ring-PET and a DH-PET. Ring-PET studies were performed 45-75 min postinjection and were followed by a DH-PET scan approximately 3 h postinjection. Number and location of the hypermetabolic lesions detected on DH-PET and Ring-PET reconstructed images were blindly assessed by three independent observers. RESULTS: DH-PET identified all 14 head lesions detected by Ring-PET, 53 of 63 thoracic lesions and 36 of 45 abdominal lesions. Of the 19 lesions not identified by DH-PET, 6 were smaller than 10 mm, 8 were between 10 and 15 mm and 1 was 18 mm; dimensions of 4 bone lesions were not available. A concordant restaging, based on location and number of lesions detected, was found in all 14 patients with head tumors, in 28 of 30 patients with thoracic tumors and in 24 of 26 patients with abdominal tumors. CONCLUSION: We found a good agreement between Ring-PET and DH-PET assessment of oncologic patients in detecting hypermetabolic lesions > or = 10-15 mm.

Decision tree sensitivity analysis for cost-effectiveness of FDG-PET in the staging and management of non-small-cell lung carcinoma.

UNLABELLED: Preliminary studies have shown that PET is more accurate than CT for the staging of non-small-cell lung carcinoma (NSCLC). However, the potential effect of PET on the management of these patients and its cost-effectiveness has not been rigorously studied. Thus, we have used decision tree sensitivity analysis to assess the cost-effectiveness of a PET based strategy for staging of NSCLC. METHODS: Two decision strategies for selection of potential surgical candidates were compared; thoracic CT alone or thoracic CT and thoracic PET. The first decision tree was conservatively constructed by requiring mediastinoscopy (biopsy) to confirm imaging results so that no patient with surgically curable disease would miss the opportunity for surgery in either strategy. A second less conservative tree in which only nonconcordant results are biopsied was also tested. The various paths of each strategy are dependent on numerous parameters which were determined from a review of the medical literature. Life expectancy was calculated using the declining exponential approximation of life expectancy and reduced based on procedural mortality. Costs were based on mean costs at our institution. For all possible outcomes of each strategy, the expected cost and projected life expectancy were determined. The effect of changing one or more parameters on the expected cost and life expectancy were studied using a sensitivity analysis. RESULTS: The CT + PET strategy in the conservative decision tree showed a saving of $1154 per patient without a loss of life expectancy (increase of 2.96 days) as compared to the alternate strategy of CT alone. Both these effects were the result of improved staging of lung carcinoma prior to the decision for surgery. The CT + PET strategy in the less conservative decision tree showed a savings of $2267 per patient but misses 1.7% of potentially operable patients. CONCLUSION: These results show through rigorous decision tree analysis, the potential cost-effectiveness of using FDG PET in the management of NSCLC. These results form a basis for detailed study of the results obtained from multicenter trials on the accuracy of PET in NSCLC management. Furthermore, the techniques utilized for decision tree analysis have broad range of applicability to the entire field of nuclear medicine.

Whole-body FDG-PET imaging for staging of Hodgkin's disease and lymphoma.

UNLABELLED: Accurate staging of Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) is important for treatment management. In this study, the utility of 2-[18F]fluoro-2-deoxy-D-glucose (FDG) whole-body PET was evaluated as an imaging modality for initial staging or restaging of 7 HD and 11 NHL patients. METHODS: Whole-body PET-based staging results were compared to the patient's clinical stage based on conventional staging studies, which included combinations of CT of the chest, abdomen and pelvis, MRI scans, gallium scans, lymphangiograms, staging laparatomies and bone scans. RESULTS: Accurate staging was performed in 17 of 18 patients using a whole-body PET-based staging algorithm compared to the conventional staging algorithm in 15 of 18 patients. In 5 of 18 patients, whole-body PET-based staging showed additional lesions not detected by conventional staging modalities, whereas conventional staging demonstrated additional lesions in 4 of 18 patients not detected by whole-body PET. The total cost of conventional staging was $66,292 for 16 CT chest scans, 16 CT abdominal/pelvis scans, three limited MRI scans, four bone scans, five gallium scans, two laparotomies and one lymphangiogram. In contrast, scans cost $36,250 for 18 whole-body PET studies and additional selected correlative studies: one plain film radiograph, one limited CT, one bone marrow scan, one upper GI and one endoscopy. CONCLUSION: A whole-body FDG-PET-based staging algorithm may be an accurate and cost-effective method for staging or restaging HD and NHL.

PET in lung cancer.

An estimated 180,000 new cases of lung cancer will be diagnosed in the U.S. this year, and lung cancer accounts for approximately 25% of all cancer deaths. Most lung cancers are initially detected on chest radiographs, but many benign lesions have radiologic characteristics similar to malignant lesions. Thus, additional studies are required for further evaluation. CT is most frequently used to provide additional anatomic and morphologic information about lesions, but it is limited in distinguishing between benign and malignant abnormalities. Because of the indeterminate results obtained from anatomic images, biopsy procedures, including thoracoscopy and thoracotomy, may be used even though one half of the lesions removed are benign and do not need to be removed. Fluorodeoxyglucose (FDG) PET imaging provides physiologic and metabolic information that characterizes lesions that are indeterminate by CT, accurately stages the distribution of lung cancer and provides prognostic information. FDG PET imaging takes advantage of the increased accumulation of FDG in transformed cells and is sensitive (approximately 95%) to the detection of cancer in patients who have indeterminate lesions on CT. The specificity (approximately 85%) of PET imaging is slightly less than its sensitivity because some inflammatory processes, such as active granulomatous infections, avidly accumulate FDG. The high negative predictive value of PET suggests that lesions considered negative on the study are benign, biopsy is not needed and radiographic follow-up is recommended. Several studies have documented the increased accuracy of PET compared with CT in the evaluation of the hilar and mediastinal lymph-node status in patients with lung cancer. Whole-body PET studies detect metastatic disease that is unsuspected by conventional imaging and demonstrate some of the anatomic abnormalities detected by CT to be benign lesions. Management changes have been reported in up to 41% of patients on the basis of the results of whole-body studies.

Cost-effectiveness analysis of therapy for symptomatic carotid occlusion: PET screening before selective extracranial-to-intracranial bypass versus medical treatment.

UNLABELLED: The St. Louis Carotid Occlusion Study (STLCOS) demonstrated that increased cerebral oxygen extraction fraction (OEF) detected by PET scanning predicted stroke in patients with symptomatic carotid occlusion. Consequently, a trial of extracranial-to-intracranial (EC/IC) arterial bypass for these patients was proposed. The purpose of this study was to examine the cost-effectiveness of using PET in identifying candidates for EC/IC bypass. METHODS: A Markov model was created to estimate the cost-effectiveness of PET screening and treating a cohort of 45 symptomatic patients with carotid occlusion. The primary outcome was incremental cost for PET screening and EC/IC bypass (if OEF was elevated) per incremental quality-adjusted life year (QALY) saved. Rates of stroke and death with surgical and medical treatment were obtained from EC/IC Bypass Trial and STLCOS data. Costs were estimated from the literature. Sensitivity analyses were performed for all assumed variables, including the PET OEF threshold used to select patients for surgery. RESULTS: In the base case, PET screening of the cohort followed by EC/IC bypass on 36 of the 45 patients yielded 23.2 additional QALYs at a cost of $20,000 per QALY, compared with medical therapy alone. A more specific PET threshold, which identified 18 surgical candidates, gained 22.6 QALYs at less cost than medical therapy alone. The results were sensitive to the perioperative stroke rate and the stroke risk reduction conferred by EC/IC bypass surgery. CONCLUSION: If postoperative stroke rates are similar to stroke rates observed in the EC/IC Bypass Trial, EC/IC bypass will be cost-effective in patients with symptomatic carotid occlusion who have increased OEF. A clinical trial of medical therapy versus PET followed by EC/IC bypass (if OEF is elevated) is warranted.