Positron emission tomography of lung tumors and mediastinal lymph nodes using [18F]fluorodeoxyglucose. The Members of the PET-Lung Tumor Study Group

Mediastinal recurrence after curative resection of colon cancer: A case report and review of literature

Colorectal carcinoma is one of the most common and significant causes of cancer-related death. Metastasis to mediastinal lymph nodes and/or pleura without liver or lung involvement is an atypical pattern of colon cancer metastasis. A 70-year-old male underwent curative right side hemicolectomy and omentectomy for ascending colon cancer followed by adjuvant chemotherapy. Around nine months after surgery, the patient was noted to have bilateral large pleural effusions on the restaging computed tomography scan of the chest/abdomen/pelvis. No intraabdominal or intrathoracic mass/metastasis was seen on the imaging. Multiple thoracentesis performed over the course of next few months revealed exudative effusion but failed to demonstrate malignant cells. A few months later, new mediastinal and right hilar lymphadenopathy was noted on the repeat computed tomography scan. A subsequent positron-emission tomography scan revealed multiple sites of fluorodeoxyglucose (FDG)-avid mediastinal lymphadenopathy. The sites of pleural effusion were not fluorodeoxyglucose-avid. Endobronchial ultrasound and biopsy of mediastinal nodes showed adenocarcinoma with signet-ring features. Immunohistochemistry confirmed the diagnosis of metastatic colon cancer. Systemic treatment with chemotherapy was initiated. Our case highlights the importance of mediastinal evaluation by imaging during the follow-up of patients with colorectal carcinoma. The ideal management strategy for mediastinal metastasis of colorectal carcinoma remains a question, two major options being local metastasectomy or systemic chemotherapy.

Lung cancer imaging

Lung cancer remains the leading cause of cancer-related deaths in the US. Imaging plays an important role in the diagnosis, staging, and follow-up evaluation of patients with lung cancer. With recent advances in technology, it is important to update and standardize the radiological practices in lung cancer evaluation. In this article, the authors review the main clinical applications of different imaging modalities and the most common radiological presentations of lung cancer.

Pulmonary hamartoma resembling multiple metastases: A case report

The current study presents the case of a patient with multiple pulmonary nodules as observed by computed tomography. Furthermore, a marginal increase in fluorodeoxyglucose uptake was identified by positron emission tomography. Due to the appearance of multiple small nodules and a history of radical nephrectomy, a hypothetical diagnosis of pulmonary metastasis of a previously excised renal carcinoma was determined, which was confirmed by biopsy. Video-assisted thoracoscopic surgical resection of the nodules was proposed and pathological examination exhibited an unforeseen and rare observation.

PCK2 activation mediates an adaptive response to glucose depletion in lung cancer

Cancer cells are reprogrammed to utilize glycolysis at high rates, which provides metabolic precursors for cell growth. Consequently, glucose levels may decrease substantially in underperfused tumor areas. Gluconeogenesis results in the generation of glucose from smaller carbon substrates such as lactate and amino acids. The key gluconeogenic enzyme, phosphoenolpyruvate carboxykinase (PEPCK), has been shown to provide metabolites for cell growth. Still, the role of gluconeogenesis in cancer is unknown. Here we show that the mitochondrial isoform of PEPCK (PCK2) is expressed and active in three lung cancer cell lines and in non-small cell lung cancer samples. PCK2 expression and activity were enhanced under low-glucose conditions. PEPCK activity was elevated threefold in lung cancer samples over normal lungs. To track the conversion of metabolites along the gluconeogenesis pathway, lung cancer cell lines were incubated with (13)C₃-lactate and label enrichment in the phosphoenolpyruvate (PEP) pool was measured. Under low glucose, all three carbons from (13)C₃-lactate appeared in the PEP pool, further supporting a conversion of lactate to pyruvate, via pyruvate carboxylase to oxaloacetate, and via PCK2 to phosphoenolpyruvate. PCK2 small interfering RNA and the pharmacological PEPCK inhibitor 3-mercaptopicolinate significantly enhanced glucose depletion-induced apoptosis in A549 and H23 cells, but not in H1299 cells. The growth of H23 multicellular spheroids was significantly reduced by 3-mercaptopicolinate. The results of this study suggest that lung cancer cells may utilize at least some steps of gluconeogenesis to overcome the detrimental metabolic situation during glucose deprivation and that in human lung cancers this pathway is activated in vivo.

The value of delayed (18)F FDG-PET imaging in diagnosis of solitary pulmonary nodules: A preliminary study on 28 patients

OBJECTIVE

The aim of this study was to investigate whether adding delayed phase imaging can improve diagnostic ability of (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) in evaluating solitary pulmonary nodules (SPNs).

MATERIALS AND METHODS

28 patients with SPNs received dual-phase (18)F-FDG PET at 1h and 2h after (18)F-FDG injection during Feb 2009 to Jun 2011were included in this retrospective study. Their final diagnosis was confirmed by pathological examination in 27 cases and clinical follow-up in 1 case. The standardized uptake value (SUV) of early and delayed phases of all lesions was measured.

RESULTS

The 28 SPNs included 9 benign lesions and 19 malignant lesions. Using SUV ≥2.5 as a criteria for malignancy, the sensitivity, specificity, and accuracy were 52.6%, 55.6% and 53.6% respectively at early phase; 68.4%, 55.6% and 64.3% respectively at early and delayed phases combined. Combined early and delayed phase scans combined picked up 3 additional malignant lesions from the 14 lesions with an initial SUV value less than 2.5, and there was no additional false positive result with the benign lesions.

CONCLUSION

Adding delayed phase scanning resulted in correct diagnosis of three malignant lesions with an initial SUV value less than 2.5. Delayed phase scanning can be recommended in the SPNs with SUV less than 2.5 at early phase.

A validated bioanalytical HPLC method for pharmacokinetic evaluation of 2-deoxyglucose in human plasma

2-Deoxyglucose (2-DG), an analog of glucose, is widely used to interfere with glycolysis in tumor cells and studied as a therapeutic approach in clinical trials. To evaluate the pharmacokinetics of 2-DG, we describe the development and validation of a sensitive HPLC fluorescent method for the quantitation of 2-DG in plasma. Plasma samples were deproteinized with methanol and the supernatant was dried at 45°C. The residues were dissolved in methanolic sodium acetate-boric acid solution. 2-DG and other monosaccharides were derivatized to 2-aminobenzoic acid derivatives in a single step in the presence of sodium cyanoborohydride at 80°C for 45 min. The analytes were separated on a YMC ODS C₁₈ reversed-phase column using gradient elution. The excitation and emission wavelengths were set at 360 and 425 nm. The 2-DG calibration curves were linear over the range of 0.63-300 µg/mL with a limit of detection of 0.5 µg/mL. The assay provided satisfactory intra-day and inter-day precision with RSD less than 9.8%, and the accuracy ranged from 86.8 to 110.0%. The HPLC method is reproducible and suitable for the quantitation of 2-DG in plasma. The method was successfully applied to characterize the pharmacokinetics profile of 2-DG in patients with advanced solid tumors.

Combining transbronchial biopsy using endobronchial ultrasonography with a guide sheath and positron emission tomography for the diagnosis of small peripheral pulmonary lesions

To evaluate the combination of transbronchial biopsy (TBB) using endobronchial ultrasonography with a guide sheath (EBUS-GS) and positron emission tomography with fluorodeoxyglucose (FDG-PET) for the diagnosis of small peripheral pulmonary lesions (PPLs) < or = 30 mm in mean diameter. A total of 74 PPLs (69.2%) were diagnosed by TBB using EBUS-GS with X-ray fluoroscopy. Diagnostic yield by FDG-PET was 78.5% for the 107 PPLs examined. Diagnostic yield with the combination of TBB using EBUS-GS and FDG-PET (90.7%) was significantly higher compared with that for each procedure alone. A significant increment in diagnostic yield with this combination was seen for PPLs >20mm and < or = 30 mm and for malignant lesions. Combination of TBB using EBUS-GS and FDG-PET is useful for the diagnosis of small PPLs.

Pleomorphic carcinoma of the lung with intrapulmonary aerogenic metastases on FDG PET

A 59-year-old man presented with hemoptysis. Chest x-ray and computed tomography showed a cavitating mass and ground glass opacities in the right lower lobe. Positron emission tomography showed large regions of markedly increased fluorodeoxyglucose uptake in the right lower lobe consistent with primary cancer and intrapulmonary metastases, and several foci of high fluorodeoxyglucose uptake in the mediastinum and left neck consistent with lymph node metastases. We concluded that ground glass opacities were not aspiration of blood but intrapulmonary aerogenic metastases. Continuous active bleeding from the right bronchus (B6) was confirmed by bronchoscopy, and the right lower lobe was resected to remove the bleeding source. Pathologic findings showed pleomorphic carcinoma of the lung with intrapulmonary aerogenic metastases.

An unusual presentation of a sarcoidosis that mimicked lymphatic metastatize non small cell lung carcinoma in positron emission tomography: a case report

In the last decade, several sophisticated and accurate imaging methods such as positron emission tomography have been developed in order to evaluate malignant potential in enlarged mediastinal lymph nodes. This case illustrates an unusual presentation of sarcoidosis that mimicked lymphatic metastases of non small cell lung carcinoma. The reported high specificity and sensitivity of positron emission tomography-Computer Tomography regarding mediastinal staging could lead in same cases of false positives to a delaying of stage adapted therapy of non small cell lung carcinoma, showing that despite the recent advances of imaging techniques, such as positron emission tomography-computer tomography, several limitations of this imaging technique are still existing.

Does the availability of positron emission tomography modify diagnostic strategies for solitary pulmonary nodules? An observational study in France

Background

Previous studies showed that at the individual level, positron emission tomography (PET) has some benefits for patients and physicians in terms of cancer management and staging. We aimed to describe the benefits of (PET) in the management of solitary pulmonary nodules (SPNs) in a population level, in terms of the number of diagnostic and invasive tests performed, time to diagnosis and factors determining PET utilization.

Methods

In an observational study, we examined reports of computed tomography (CT) performed and mentioning "spherical lesion", "nodule" or synonymous terms. We found 11,515 reports in a before-PET period, 2002–2003, and 20,075 in an after-PET period, 2004–2005. Patients were followed through their physician, who was responsible for diagnostic management.

Results

We had complete data for 112 patients (73.7%) with new cases of SPN in the before-PET period and 250 (81.4%) in the after-PET period. Patients did not differ in mean age (64.9 vs. 64.8 years). The before-PET patients underwent a mean of 4 tests as compared with 3 tests for the after-PET patients (p = 0.08). Patients in the before-PET period had to wait 41.4 days, on average, before receiving a diagnosis as compared with 24.0 days, on average, for patients in the after-PET period who did not undergo PET (p < 0.001). In the after-PET period, 11% of patients underwent PET during the diagnostic process. A spiculated nodule was more likely to determine prescription for PET (p < 0.001). Multivariate analysis revealed that patients in both periods underwent fewer tests when PET was prescribed by general practitioners (p < 0.001) and if the nodule was not spiculated (p < 0.001). The proportion of unnecessary invasive approaches prescribed (47% vs. 49%) did not differ between the groups.

Conclusion

In our study, 1 year after the availability of PET, the technology was not the first choice for diagnostic management of SPN. Even though we observed a tendency for reduced number of tests and mean time to diagnosis with PET, these phenomena did not fully relate to PET availability in health communities. In addition, the availability of PET in the management of SPN diagnosis did not reduce the overall rate of unnecessary invasive approaches.

Positron emission tomography in lung cancer

Recent advances in positron emission tomography (PET) with 2-deoxy-2-fluoro [F-18]-D: -glucose (FDG) has enabled not only the diagnosis and staging of lung cancer but also the prediction of its malignancy grade. However, FDG-PET has been known to have several pitfalls for imaging of lung cancer. For the effective clinical use of FDG-PET in lung cancer, we reviewed the pitfalls of using FDG-PET in the diagnosis of pulmonary nodules, semiquantitative analysis of FDG-uptake, N-staging, prediction of tumor aggressiveness, prognostic significance, and prediction of pathological response after chemoradiotherapy.

False-negative PET scan with bronchioloalveolar carcinoma: an important diagnostic caveat

Positron emission tomography (PET) is becoming widely accepted as a powerful diagnostic tool for the diagnosis of lung cancer, but it has very poor sensitivity for the detection of bronchioloalveolar carcinoma (BAC) and adenocarcinoma with BAC pattern, the less common form of pulmonary neoplasia. We present a case of a patient with a negative PET scan who might have been followed by observation but was found to have bronchioloalveolar carcinoma at thoracotomy. PET has a reported sensitivity of over 98% in most series but misses almost two-thirds of BAC lesions, which might delay invasive testing and early diagnosis of this potentially lethal cancer. Although this diagnostic limitation has been well reported in the radiology literature, the high reported sensitivity and sensitivity can give clinicians a false sense of security with negative PET scans of lung nodules. The usual risk factors for bronchogenic carcinoma are less reliable for these subtypes of non-small-cell lung cancer; thus, clinicians need to have a high index of suspicion for BAC and exercise caution when making decisions on the basis of PET.

Clinical characteristics of a second small nodule(s) associated with cT1-2N0M0 non-small-cell lung cancer

When a patient with cT(1-2)N(0)M(0) stage non-small-cell lung cancer (NSCLC) has a second small nodule(s), the treatment plan and prognosis depend largely on whether the nodule is benign or malignant. However, the incidence of malignancy of nodules associated with N(0) and M(0) NSCLC is unknown. Furthermore, predictive factors of malignancy have not been defined. Thus, we evaluated the nature of nodules that were less than 15 mm in diameter associated with stage T(1-2)N(0)M(0), and tried to identify clinical and radiologic factors predictive of malignancy. The study population consisted of 39 patients with T(1-2)N(0)M(0) NSCLC and a second nodule(s) less than 1.5 cm and who had received curative resection. Medical records and radiologic findings, including CT scans of the chest, were retrospectively reviewed. Nodules were finally diagnosed as benign in 85% and malignant in 15%. No significant differences in terms of gender, age, preoperative carcinoembryonic antigen (CEA) level, cell type, pathologic stages, shape, size, location and number of nodules, or the presence of calcification around nodules was observed between benign and malignant groups. We suggest that if primary NSCLC is resectable, an effort should be made to confirm the pathologic diagnosis of nodules. If histologic findings in nodules are not available, surgical resection should be actively considered, especially when nodules < 1.5 cm are associated with N(0) or M(0) NSCLCs.

Additional value of integrated PET-CT in the detection and characterization of lung metastases: correlation with CT alone and PET alone

The purpose was evaluating retrospectively the additional value of integrated positron emission tomography (PET) and computed tomography (CT) in the detection of pulmonary metastases in comparison with CT and PET alone. Fifty-six lung nodules, divided into three groups according their size, detected in 24 consecutive patients with a known primary tumor were retrospectively evaluated with integrated PET-CT, CT and PET. The nature of these nodules was determined by either histopathology or a follow-up of at least 6 months. The CT and PET images of the integrated PET-CT were evaluated separately by a radiologist and a nuclear medicine physician, the integrated PET-CT images were evaluated by a chest radiologist and nuclear medicine physician in consensus. The investigators were asked to search lung nodules and to determine whether these nodules were metastases or not. Sensitivity and accuracy for CT, PET and integrated PET-CT for characterization of all pulmonary nodules were, respectively: 100%, 90%, 100% and 57%, 55%, 55%. There was no significant difference in the characterization of pulmonary nodules between integrated PET-CT and CT alone (P=1.000) and PET alone (P=0.1306). An accurate evaluation is only possible for lesions larger than 1 cm.

Positron emission tomography with CT in the evaluation of non-small cell lung cancer in populations with a high prevalence of tuberculosis

OBJECTIVE AND BACKGROUND

To determine the utility of positron emission tomography with CT (PET-CT) in the evaluation of non-small cell lung cancer (NSCLC) in an Asian context where tuberculosis rates are moderately high.

METHODS

Case records of consecutive patients with NSCLC undergoing PET-CT at the Singapore General Hospital over a 1-year period were retrospectively reviewed. The authors evaluated the sensitivity and specificity of PET-CT at their institution using surgical pathology or the tincture of time as the gold standard.

RESULTS

A total of 54 patients underwent PET-CT during this period. Seven patients were evaluated for solitary pulmonary nodule, for which PET-CT gave a sensitivity of 100% and specificity of 75%. There was one patient with false positive PET-CT due to active tuberculosis. In total, 41 patients underwent PET-CT for staging of NSCLC. There was one false positive (patient was found to have active tuberculous lymphadenitis) and one false negative for NSCLC. This gave a sensitivity of 92.3% and a specificity of 95%. Histology from the adrenal glands was available in two patients with PET-CT that was positive for adrenal metastases. One proved to be benign whereas the other was consistent with metastasis. Two patients had PET-CT positive for liver metastases, which was verified by histology. Two patients with positive PET-CT for lesions in the colon turned out to be benign histologically.

CONCLUSIONS

Positron emission tomography with CT for the evaluation and follow-up of solitary pulmonary nodule and NSCLC can provide additional useful information to conventional radiology for treatment planning and a non-invasive determination of prognosis. However, physicians need to be aware of the limitations of this imaging modality, particularly when tuberculosis has a high prevalence in the population.

Meta-analysis of positron emission tomographic and computed tomographic imaging in detecting mediastinal lymph node metastases in nonsmall cell lung cancer

A systematic review was undertaken to select studies that compared the accuracy of 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography with computed tomographic imaging in detecting mediastinal lymph node metastases in patients with nonsmall cell lung cancer. Two authors selected relevant articles according to predefined criteria. With a meta-analytic method, summary receiver operating characteristic curves were constructed. The point on the receiver operating characteristic curve with equal sensitivity and specificity for 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography was Q* = 0.90 (95% confidence interval [CI], 0.86 to 0.95). For computed tomography it was 0.70 (95% CI, 0.65 to 0.75). The difference was highly significant (p < 0.0001). We conclude that 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography is more accurate than computed tomography in detecting mediastinal lymph node metastases.

Lung Nodule Detection and Characterization With Multi-Slice CT

The influence of MSCT on nodule detection and characterization will be discussed. The objective is to improve understanding of the clinical issues involved in nodule detection, characterization, and management in light of technological advances. Topics to be covered are noninvasive characterization techniques, such as morphologic and density inspection on CT, nodule enhancement techniques, CT-PET, temporal nodule size assessment, and computer aided diagnosis for both detection and characterization.

The Utility of 2-Deoxy-2-[F-18]fluoro-d-glucose Positron Emission Tomography in the Investigation of Patients with Disseminated Carcinoma of Unknown Primary Origin

PURPOSE

A retrospective analysis of the use of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) positron emission tomography (PET) was performed in patients with histologically proven disseminated carcinoma of unknown primary tumor (CUP).

PROCEDURES

The records of 31 patients with CUP, excluding patients with isolated neck metastases, were reviewed to identify the ability of PET to detect the putative primary site (PPS) and/or to change therapeutic management.

RESULTS

In eight out of 31 cases (26%), a PPS was confirmed, either definitively (one pathologically, one radiologically) (true positive) or clinically (six cases). For three cases (10%), histological evidence of a primary tumor distant from the PPS was found (false positive). In a further seven cases (23%), the PPS remained unconfirmed, whereas for 13 cases (42%) no PPS was identified. In five out of seven patients in whom the PET suggested a high probability of having identified the primary site, the PPS was confirmed definitively or clinically. PET altered clinical management in at least 12 cases (38%).

CONCLUSIONS

PET contributed to the management of previously extensively investigated patients with CUP. Identification of a PPS and/or change in management was documented in 38% of cases, the majority of which were lung or pancreatic cancer. These findings are worthy of evaluation in a prospective study.

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.

Visual and Semiquantitative Analyses for F-18 Fluorodeoxyglucose PET Scanning in Pulmonary Nodules 1 cm to 3 cm in Size

BACKGROUND

While visual assessment is the simplest way to evaluate positron emission tomography (PET) with fluorodeoxyglucose (FDG), faintly positive nodules are often difficult to evaluate. We performed visual and semiquantitative analyses of pulmonary nodules from 1 to 3 cm in size to determine the optimal method of analysis for PET data, especially for faintly positive nodules on visual assessment.

METHODS

Positron emission tomography data were analyzed for 161 pulmonary nodules from 1 to 3 cm in size (108 malignant and 53 benign nodules). On visual assessment, FDG uptake by the nodules was classified into three grades in comparison with mediastinal blood pool, (ie, definitely positive, faintly positive, and negative). In addition, FDG uptake was measured by the standard uptake value (SUV), the contrast ratio to the contralateral lung (CR-lung), and the contrast ratio to the cerebellum (CR-brain). Cut-off values for each variable were determined from receiver operating characteristics (ROC) curves, and the values were 2.5 for the SUV, 0.4 for the CR-lung, and 0.25 for the CR-brain. Nodules with FDG uptake above these cut-off values were defined as positive in each method.

RESULTS

Visual assessment showed definitely positive for 80 nodules (64 malignant and 16 benign), faintly positive for 22 (17 malignant and 5 benign), and negative for 59 nodules (27 malignant and 32 benign). In the 139 nodules that were definitely positive or negative by visual assessment, there were no significant differences of sensitivity and specificity among the four methods (visual assessment, SUV, CR-lung, and CR-brain). In the 17 malignant nodules that were faintly positive, the SUV did not detect any true-positive nodules, but the CR-lung and CR-brain showed 9 and 5 true-positive nodules, respectively, resulting in a significantly higher sensitivity than the SUV (p < 0.001 and p = 0.02, respectively). Fifteen of 17 faintly positive malignant nodules (88%) were histologically well- or moderately-differentiated adenocarcinoma.

CONCLUSIONS

The semiquantitative methods (SUV, CR-lung, and CR-brain) do not improve the efficacy of visual assessment alone for nodules graded as definitely positive or negative. However, faintly positive nodules on visual assessment should be evaluated by the CR-lung or CR-brain rather than the SUV, and are often differentiated adenocarcinomas.

Advances in positron emission tomographic imaging of lung cancer

Positron emission tomography (PET) with [18F]fluorodeoxyglucose (FDG) has been established as a useful tool in the management of patients with non-small cell lung cancer and promises to be as valuable in the clinical management of other cancers. PET imaging with FDG allows the assessment of tumor glucose metabolism in vivo; however, a number of other PET tracers are being used in oncologic research to assess changes in other cellular processes associated with malignant transformation of the cell. [11C]-Labeled methionine and choline are being used to assess changes in cell membrane synthesis; however, small studies have not shown the added information from these tracers to be clinically useful. DNA synthesis can be assessed by measuring the uptake of the thymidine analog 3'-deoxy-3'-[18F]fluorothymidine, which may be more specific for evaluating malignancy without the problem of false-positive results from inflammatory lesions, as seen with FDG. Tumor hypoxia imaging with copper-labeled diacetyl-bis(N(4)-methylthiosemicarbazone) or [18F]fluoromisonidazole may provide a better method of predicting which tumors will respond best to conventional therapy. The role of PET will continue to evolve with further clinical studies using these and other new tracers.

Evaluation of F-18 fluorodeoxyglucose (FDG) PET scanning for pulmonary nodules less than 3 cm in diameter, with special reference to the CT images

BACKGROUND

While pulmonary nodules can be substantially divided into solid and ground-glass opacity (GGO) ones on CT image, they have different biological natures which could cause false positive or false negative to diagnose malignancy on positron emission tomography with fluorodeoxyglucose (FDG-PET). To determine the effectiveness of PET for small pulmonary nodules, the nodules were classified into solid and GGO ones, of which results were compared with the data of PET scans. The lower limit size of nodules for PET imaging was also evaluated.

METHODS

Prospective FDG-PET scans were undertaken for 136 non-calcified nodules less than 3 cm in diameter. CT density histograms were made for each nodule to classify into solid and GGO ones.

RESULTS

Eighty-one nodules were malignant and 55 were benign. All of the 20 nodules less than 1 cm in diameter (n = 8 in malignant, n = 12 in benign), were negative on PET regardless of the histology. In the 116 nodules 1-3 cm in diameter (n = 73 in malignant, n = 43 in benign), there were 15 false negative and 15 false positive nodules, with a sensitivity of 79% and specificity of 65%. CT density histograms showed 101 solid nodules (n = 63 in malignant, n = 38 in benign) and 15 GGO nodules ( n = 10 in malignant, n = 5 in benign). All of the 10 malignant nodules with GGO images were histologically well-differentiated adenocarcinoma and 9 of them (90%) were false negative on PET. Four of the 5 (80%) benign nodules with GGO images were focal pneumonia with well-preserved air spaces, causing false positive on PET. Sensitivity and specificity for nodules with GGO images were 10 and 20%, respectively, which were significantly lower than 90 and 71% for nodules with solid images (P < 0.001).

CONCLUSION

Pulmonary nodules which are less than 1cm in size or show GGO images on CT cannot be evaluated accurately by PET.

Surgical exploration of the mediastinum: mediastinoscopy and intraoperative staging

Lung resection remains the therapy of choice offering the greatest potential for cure in non-spread lung cancer. Prognostic importance of lymph-node involvement has been underlined by several studies. So, exploration of the mediastinum is of major importance for defining the therapeutic strategy in a possibly curative setting. Pre-resectional exploration of the mediastinal lymph-nodal status is mandatory to define tumour stage exactly and establish specific therapy. Cervical mediastinoscopy is the primary diagnostic procedure and remains the gold standard in invasive surgical staging. Complementary, parasternal mediastinoscopy, extended mediastinoscopy, and video-assisted thoracoscopy may be performed. These techniques allow accurate assessment of mediastinal lymph-node involvement, resulting in an appropriate judgement as to resectability and possible treatment options. Different techniques are established for intraoperative exploration and staging. In terms of curative surgery of lung cancer we demand accurate staging which is achieved by systematic and complete Lymph-node dissection. So, individually and dependent on primary tumour site, accurate mediastinal staging of Lung cancer should be performed in combination with definitive lung resection.

Seeking a home for a PET, part 1: Defining the appropriate place for positron emission tomography imaging in the diagnosis of pulmonary nodules or masses

There is a growing experience with positron emission tomography (PET) in patients with pulmonary nodules or masses. As PET imaging becomes more widely available, it is important to thoughtfully define when application of this technology is warranted. Review of the literature to date suggests that PET imaging for diagnosis of pulmonary lesions is most useful in patients who have a low or intermediate risk of lung cancer as determined by an evaluation of symptoms, risk factors, and radiographic appearance. There is little role for PET in diagnosis in patients with a very low or a high risk of lung cancer, and there is little role in patients with lesions < 1 cm in diameter, or lesions suspected to be an infection, a bronchioloalveolar carcinoma, or a typical carcinoid tumor.

The size of metastatic foci and lymph nodes yielding false-negative and false-positive lymph node staging with positron emission tomography in patients with lung cancer

BACKGROUND

We examined the sizes of lymph nodes and metastatic foci within the lymph nodes that affect false-positive and false-negative lymph node staging by positron emission tomography in lung cancer.

METHODS

Preoperative positron emission tomography and computed tomography scans were performed for 564 lymph node stations in 80 patients with peripheral-type lung cancer. The sizes of both the lymph nodes and the metastatic foci within the lymph nodes were measured, and these measurements were compared with those obtained with positron emission tomography scanning. To establish general sizes of metastatic foci within the lymph nodes, 277 metastatic lymph nodes in operative specimens previously resected from another 111 patients with lung cancer were examined as a control.

RESULTS

The sensitivity was significantly higher for positron emission tomography than for computed tomographic scanning (P =.026). The sizes of metastatic foci within lymph nodes that showed false-negative (n = 8) and true-positive (n = 28) with positron emission tomography ranged from 0.5 to 9 mm (3 +/- 1 mm) and from 4 to 18 mm (10 +/- 3 mm), respectively (P <.001). None of the metastatic foci smaller than 4 mm could be detected with positron emission tomography scanning. The review of the 277 previously resected metastatic lymph nodes showed that 89 (32%) had metastatic foci smaller than 4 mm. The sizes of true-positive (n = 28) and false-positive (n = 10) lymph nodes ranged from 6 to 15 mm (10 +/- 2 mm) and from 9 to 16 mm (12 +/- 2 mm), respectively (P <.01). None of the false-positive lymph nodes was smaller than 9 mm.

CONCLUSIONS

Although positron emission tomography was superior to computed tomography scanning in lymph node staging in lung cancer, positron emission tomography was unable to distinguish metastatic foci smaller than 4 mm, which were not unusual sizes for lymph node metastases in lung cancer. Positive lymph nodes with positron emission tomography smaller than 9 mm are likely to be true-positive rather than false-positive.

Clinical use of fluorodeoxyglucose F 18 positron emission tomography for detection of renal cell carcinoma

PURPOSE

We evaluate the role of fluorodeoxyglucose F 18 positron emission tomography (PET) in patients with renal cell carcinoma (RCC) by retrospective review. To our knowledge this series is the largest reviewing the use of PET in patients with RCC.

MATERIALS AND METHODS

A total of 66 patients who underwent 90 PET scans for suspected or known RCC were identified. Dictated reports of PET, chest computerized tomography (CT), abdominal/pelvic CT and bone scan were examined with confirmation of results by histopathology or followup of at least 1 year. The accuracies of PET and conventional imaging modalities were compared.

RESULTS

PET exhibited a sensitivity of 60% and specificity of 100% for primary RCC tumors (abdominal CT demonstrated 91.7% sensitivity and 100% specificity). For retroperitoneal lymph node metastases and/or renal bed recurrence, PET was 75.0% sensitive and 100.0% specific (92.6% sensitivity and 98.1% specificity for abdominal CT). PET had a sensitivity of 75.0% and a specificity of 97.1% for metastases to the lung parenchyma compared to 91.1% and 73.1%, respectively, for chest CT. PET had a sensitivity of 77.3% and specificity of 100.0% for bone metastases, compared to 93.8% and 87.2% for combined CT and bone scan. In 39 scans (32 patients) PET failed to detect RCC lesions identified by conventional imaging.

CONCLUSIONS

The role of fluorodeoxyglucose F 18 PET in the detection of RCC is limited by low sensitivity. With superior specificity PET may have a complementary role as a problem solving tool in cases that are equivocal on conventional imaging.

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.

Narrow time-window dual-point 18F-FDG PET for the diagnosis of thoracic malignancy

Dual time-point imaging has been proposed as a means of improving the accuracy of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) for the diagnosis of malignant pulmonary nodules. The purpose of this study was to evaluate a dual time-point protocol that has a narrow time window between its initial and its delayed imaging sessions. All patients examined during a 16-month time period, either for the diagnosis of a radiographically indeterminate thoracic lesion or for the staging of non-small-cell carcinoma, were included in the study provided that they completed the dual-point protocol and had either biopsy evidence of malignancy, biopsy evidence of a benign condition involving the thoracic lesion of concern, or clinical and radiographic follow-up consistent with the absence of malignancy. The entire study population was further divided into a central subpopulation, whose index lesions were adjacent to or within the hilum or mediastinum, and a peripheral subpopulation, whose index lesions were non-central. The maximum standardized uptake value (SUV) was measured for each lesion, and various body surface areas (BSAs) and glucose corrections on the SUV were compared using discriminant analysis. BSA corrected SUVs for the initial (iSUV) and the delayed (dSUV) imaging sessions, along with their absolute difference (deltaSUV) and fractional difference (fSUV) were also compared using discriminant analysis and receiver operating characteristic (ROC) analysis. The study population consisted of 132 patients, of whom 81 had malignancy and 51 were classified as having a benign condition. Thirty-three index lesions were central and 99 were peripheral; 109 had visible uptake and 23 had such low uptake that they were not visible above background. The mean time (+/-SD) between initial and delayed imaging for the visible lesions was 31.1+/-9.4 min. With respect to the entire study population, the BSA replacement for body weight gave the best performance among the various SUV corrections examined. In addition, the BSA corrected delayed SUV (dSUV) gave a performance superior to either initial SUV (iSUV), absolute difference in SUV (deltaSUV) and fractional difference in SUV (fSUV) alone. Performance gains achieved by BSA correction and by dSUV appeared to derive primarily from the central subpopulation, thereby indicating that central lesions tend to behave differently to peripheral ones. For the central subpopulation, ROC analysis also demonstrated improved detection of malignancy from dual-point imaging. The best performance was achieved when the BSA corrected dSUV was at least 2.4, or when the fSUV showed at least a 5% increase from initial to delayed imaging. With the optimal combined dSUV/fSUV strategy, the area under the ROC curve was 0.99, as opposed to 0.96 for dSUV alone, or 0.93 for iSUV alone. The ability of 18F-FDG PET to discriminate between benign and malignant conditions of the central thorax can be improved by correcting the SUV for BSA and by increasing the 'incubation time' between 18F-FDG injection and imaging, or by performing narrow time-window dual-point imaging.

Positron emission tomography is superior to computed tomography scanning for response-assessment after radical radiotherapy or chemoradiotherapy in patients with non-small-cell lung cancer

PURPOSE

To prospectively study the capacity of positron emission tomography (PET) and computed tomography (CT) to determine response soon after radical radiotherapy or chemoradiotherapy and, thereby, predict survival. PET is known to provide a more accurate estimate of true extent of disease than CT when used to stage non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Seventy-three patients with NSCLC underwent [(18)F]fluorodeoxyglucose PET and CT scans before and after radical radiotherapy (n = 10) or chemoradiotherapy (n = 63). Follow-up PET scans were performed at a median of 70 days after radiotherapy. The median PET-CT interval was 1 day. Each patient had determinations of response to therapy made with PET and CT, categorized as complete response, partial response, no response, progressive disease, or nonassessable. Responses were correlated with subsequent survival.

RESULTS

Median survival after follow-up PET was 24 months. There was poor agreement between PET and CT responses (weighted kappa = 0.35), which were identical in only 40% of patients. There were significantly more complete responders on PET (n = 34) than CT (n = 10), whereas fewer patients were judged to be nonresponders (12 patients on PET v 20 on CT) or nonassessable (zero patients on PET v six on CT) by PET. Both CT and PET responses were individually significantly associated with survival duration; but on multifactor analysis that included the known prognostic factors of CT response, performance status, weight loss, and stage, only PET response was significantly associated with survival duration (P <.0001).

CONCLUSION

In NSCLC, a single, early, posttreatment PET scan is a better predictor of survival than CT response, stage, or pretreatment performance status.

A comparative study of 11C-choline PET and [18F]fluorodeoxyglucose PET in the evaluation of lung cancer

The purpose of this study was to compare the diagnostic value of 11C-choline positron emission tomography (PET) and [18F]fluorodeoxyglucose (FDG) PET imaging in the detection of primary lung cancer and mediastinal lymph node metastases. Seventeen patients with histologically proven primary lung cancer were examined with both 11C-choline and FDG PET within a week of each study. Lung cancers were analysed visually and semiquantitatively using the ratio of tumour-to-normal radioactivity (T/N ratio) and standardized uptake value (SUV). Mediastinal lymph node metastases were analysed visually. Although both techniques delineated focal lesions with an increase in tracer accumulation in 13 patients, FDG PET identified three additional patients in whom 11C-choline PET did not visualize any lesion. In the detection of lung cancer <2 cm in size, FDG PET provided higher sensitivity (six of seven, 85.7%) than 11C-choline PET (four of seven, 57.1%). The T/N ratio and SUV were significantly higher with FDG PET (T/N ratio, 7.43+/-6.22; SUV, 4.05+/-3.05) than these were with 11C-choline PET (T/N ratio, 2.93+/-1.19; SUV, 2.93+/-0.79) (P<0.001). There was a significant positive correlation between the T/N ratios and SUVs of FDG and 11C-choline. In the assessment of mediastinal lymph node involvement, FDG PET detected lymph node metastases in two patients who were negative on 11C-choline PET, whereas both techniques could not detect tumour involvement in one patient. Both techniques have clinical value for the non-invasive detection of primary lung cancer that is 2 cm or greater in size. However, FDG PET is superior to 11C-choline PET in the detection of lung cancer that is less than 2 cm in diameter and in mediastinal lymph node metastases.

Clinical applications of FDG-PET in oncology

Positron emission tomography together with F-18-deoxyglucose (FDG) has emerged as a valuable clinical tool in the field of oncology. FDG-PET diagnoses, stages and restages most cancers with a high diagnostic accuracy. The effects of chemotherapy on tumour metabolism can be monitored with this whole-body technique. Recent studies have established a high prognostic accuracy of PET for predicting the clinical outcome of cancer patients. The current review addresses the role of FDG-PET for diagnosing, staging and restaging of lung cancer, colorectal cancer, lymphoma, melanoma and breast cancer staging and provides a brief outlook for future applications of clinical PET imaging.

PET imaging in patients with bronchioloalveolar cell carcinoma

OBJECTIVE

Focal bronchioloalveolar cell carcinoma (BAC) has been reported as often being negative on 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG-PET) scans, but no studies have examined the FDG-PET findings of both the focal and multifocal forms of the disease. The purpose of this study was to examine the sensitivity of PET in detecting both forms of BAC.

MATERIALS AND METHODS

A retrospective review of our tumor registry revealed 15 patients who had pathologically proved BAC and who had undergone FDG-PET imaging. FDG-PET scans were interpreted as positive if the tumor demonstrated activity that was greater than the mediastinal blood pool.

RESULTS

Eight patients had focal BAC, and seven patients had multifocal disease. Nine of the 15 patients (60%) had a positive PET scan, and of these, six (67%) had multifocal disease. Six of the 15 patients (40%) had negative PET scans, and of these, five patients (83%) had the solitary form of disease. The sensitivity for focal tumors was 38%, and the sensitivity for the multifocal form was 86%.

CONCLUSIONS

Our data confirm previous reports describing a high percentage of false negative PET scans in the setting of focal BAC. However, in the presence of multifocal disease, FDG-PET seems to be highly sensitive.

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.

Lung cancer--where are we today? Current advances in staging and nonsurgical treatment

Lung cancer remains the commonest cause of cancer death in both men and women in the developed world, although mortality rates for men are dropping. Spiral computed tomography (CT) of the chest in middle-aged, smoking subjects may identify two to four times more lung cancers than a chest X-ray, with more than 70% of tumors being Stage I. The incidence of benign nodules is high, making interpretation difficult. Randomized controlled trials are required to determine whether spiral CT detects lung cancer early enough to improve mortality. Preoperative staging has relied on CT scans, but positron emission tomography scanning has greater sensitivity, specificity, and accuracy than CT and is recommended as the final confirmatory investigation when the CT shows resectable disease. In locally advanced non-small cell lung cancer, there is a small advantage for the addition of chemotherapy to radiotherapy, but no advantage for postoperative radiotherapy. Chemotherapy gives no benefit when given as neoadjuvant or adjuvant treatment around surgery. In advanced disease, newer cytotoxic agents confer a small survival advantage over older combinations, but the advantage in median survival over best supportive care remains a few months with modest improvements in quality of life. Survival with small cell lung cancer has shown little increase over the last 15 years despite multiple attempts to manipulate the timing, dose intensity of chemotherapy, and the potential of radiotherapy. Novel therapies are urgently needed for all cell types of lung cancer.

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.

Simultaneous occurrence of Hodgkin's lymphoma and eosinophilic granuloma: a potential pitfall in positron emission tomography imaging

Positron emission tomography (PET) with [18F]fluorodeoxyglucose [18F]FDG has evolved as a method of increasingly clinical importance in the management of patients with malignant lymphoma. However, inflammatory lesions also accumulate [18F]FDG and may cause difficulties with interpretation. This report deals with 2 patients with simultaneous occurrence of Hodgkin's lymphoma and eosinophilic granuloma, a rare but known coincidence of diseases. In the first case, Hodgkin's disease could not be differentiated from eosinophilic granuloma. Positron emission tomography showed increased [18F]FDG uptake both in lymphoma manifestations and in the granuloma. In the second case with proven Hodgkin's disease, post-treatment examination showed a positive PET lesion in the mediastinal residual mass, which was interpreted as viable lymphoma. However, histologic examination revealed that it was an eosinophilic granuloma.

Decision-tree sensitivity analysis for cost-effectiveness of whole-body FDG PET in the management of patients with non-small-cell lung carcinoma in Japan

BACKGROUND

Whole-body 2-fluoro-2-D-[18F]deoxyglucose [FDG] positron emission tomography (WB-PET) may be more cost-effective than chest PET because WB-PET does not require conventional imaging (CI) for extrathoracic staging.

METHODS

The cost-effectiveness of WB-PET for the management of Japanese patients with non-small-cell lung carcinoma (NSCLC) was assessed. Decision-tree sensitivity analysis was designed, based on the two competing strategies of WB-PET vs. CI. WB-PET was assumed to have a sensitivity and specificity for detecting metastases, of 90% to 100% and CI of 80% to 90%. The prevalences of M1 disease were 34% and 20%. One thousand patients suspected of having NSCLC were simulated in each strategy. We surveyed the relevant literature for the choice of variables. Expected cost saving (CS) and expected life expectancy (LE) for NSCLC patients were calculated.

RESULTS

The WB-PET strategy yielded an expected CS of $951 US to $1,493US per patient and an expected LE of minus 0.0246 years to minus 0.0136 years per patient for the 71.4% NSCLC and 34% M1 disease prevalence at our hospital. PET avoided unnecessary bronchoscopies and thoracotomies for incurable and benign diseases. Overall, the CS for each patient was $833US to $2,010US at NSCLC prevalences ranging from 10% to 90%. The LE of the WB-PET strategy was similar to that of the CI strategy. The CS and LE minimally varied in the two situations of 34% and 20% M1 disease prevalence.

CONCLUSIONS

The introduction of a WB-PET strategy in place of CI for managing NSCLC patients is potentially cost-effective in Japan.