Metastases from non-small cell lung cancer: mediastinal staging in the 1990s--meta-analytic comparison of PET and CT

Meta-analysis study of lymph node staging by 18 F-FDG PET/CT scan in non-small cell lung cancer: comparison of TB and non-TB endemic regions

Lymph node staging in non-small cell lung cancer (NSCLC) is challenging and important for deciding treatment policy. The role of PET/CT scans in lymph node staging of NSCLC remains controversial when comparing TB and non-TB endemic regions. This study systematically reviews the literature regarding the diagnostic performance of PET/CT in lymph node staging of patients with NSCLC, and determines its pooled sensitivity and specificity.

METHODS

The databases of PubMed, Medline, and Cochrane library were searched for relevant studies. Two reviewers independently assessed the methodological quality of each study. A meta-analysis of the reported sensitivity and specificity of each study was performed.

RESULTS

Seven of 86 studies were included. These studies had moderate to good methodological quality. Pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for patient-based analyses (five studies) were 66%, 92.7%, 5.86%, and 0.41%, respectively, and those for lesion-based analyses (six studies) were 59.4%, 96.5%, 9.37%, and 0.31%, respectively. Subanalysis of endemic regions of tuberculosis (TB) showed that these regions had lower sensitivity and similar specificity to non-TB endemic regions.

CONCLUSION

PET/CT showed high specificity in the lymph node staging of NSCLC and lower sensitivity in TB endemic regions.

Lymph node metastasis diagnosis using positron emission tomography with 2-[18F] fluoro-2-deoxy-D-glucose as a tracer and computed tomography in surgical cases of non-small cell lung cancer

OBJECTIVES

Positron emission tomography with 2-[18F] fluoro-2-deoxy-D-glucose as a tracer and computed tomography (FDG-PET/CT) are utilized for the diagnosis of lymph node (LN) metastasis from lung cancer. In this study, we analyzed the diagnostic ability of FDG-PET for N staging by focusing on the clinical features of false-positive (FP) and false-negative (FN) cases.

METHODS

From March 2006 to February 2010, 112 patients underwent preoperative examinations using FDG-PET/CT followed by radical resection with hilar and mediastinal dissection. We analyzed their clinicopathological characteristics based on preoperative FDG-PET/CT findings and post-operative histopathological diagnosis of resected LNs.

RESULTS

Based on the PET/CT results, 17 patients were misdiagnosed (9 FN and 8 FP). The sensitivity, specificity, accuracy and negative and positive predictive values for N1/N2 were 50.0, 94.5, 84.0, 93.0 and 58.3%, respectively, whereas those for N2 were 57.8, 90.3, 84.8, 90.3 and 61.1%, respectively. FP findings more frequently occurred in cases with elevated white blood cell (WBC) count (P=0.015) and smokers (P=0.04). In the FN group, the maximum standardized uptake value for the primary tumour was lower than that in the true-positive (TP) group (P=0.01). The short-axis sizes of 71 LNs differently diagnosed by PET/CT and histopathology findings were significantly smaller in the FN group than the TP group (P<0.001), whereas there was no difference between TP and FP. As for FN LNs in the TP group, there was no significant difference.

CONCLUSIONS

PET/CT showed a good ability to detect metastatic LNs, especially for N2 diagnosis. However, there were some limitations, especially in cases with elevated peripheral WBC count and/or smoking history.

Lung 99mTc-MIBI scintigraphy: impact on diagnosis of solitary pulmonary nodule

Most of today available non-invasive procedures cannot clearly determinate between benign and malignant solitary pulmonary nodules (SPN). The purpose of the study was to assess the possibility of using 99mTc labeled hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) to differentiate benign from malignant SPN. Sixty patients were included in the study if the CT scan showed indeterminate SPN. Prior to definitive diagnosis 99mTc-MIBI single photon emission computerized tomography (SPECT) was performed: early scan 10 minutes and delayed 60-120 minutes after the intravenous injection of 740 MBq 99mTc-MIBI using dual-headed Gamma camera. The results were considered positive if there was an increased accumulation of the radiopharmaceutical in the area of the lung corresponding to the location of the lesion. The mean nodule size ± SD measured on CT scan was 2.96 cm. Lung cancer was diagnosed in 30/60 patients (14 squamocellular, 10 adenocarcinoma, 3 large-cell and 3 microcellular lung carcinomas). Of the 30 patients with malignant lesions, 27 patients (90%) had positive 99mTc-MIBI scan results by qualitative assessment. Among benign lesions, 23/30 (76.7%) were negative on 99mTc-MIBI scan. The size and PH report of SPN is statistically significantly influencing on 99mTc-MIBI accumulation in the SPN (p<0.01). The sensitivity, specificity, accuracy, positive and negative predictive value were 90%, 76.6%, 79.4%, 88.5% and 83.3% respectively. 99mTc-MIBI SPECT is an inexpensive non-invasive diagnostic procedure which might be useful diagnostic modality in the evaluation of SPN. Easy availability and low cost makes 99mTc-MIBI SPECT an attractive method in evaluating SPN.

Diagnostic performance of integrated positron emission tomography/computed tomography for mediastinal lymph node staging in non-small cell lung cancer: a bivariate systematic review and meta-analysis

INTRODUCTION

Accurate clinical staging of mediastinal lymph nodes (MLNs) of patients with non-small cell lung cancer (NSCLC) is important in determining therapeutic options and prognoses. Integrated positron emission tomography and computed tomography (PET/CT) scanning is becoming widely used for MLN staging in patients with NSCLC. We performed a bivariate meta-analysis to determine the pooled sensitivity (SEN) and specificity (SPE) of this imaging modality.

METHODS

The PubMed/MEDLINE, Embase, and SpringerLink databases were searched for articles related to PET/CT for MLN staging in patients with NSCLC. SEN and SPE were calculated for every study. Hierarchical summary receiver operating characteristic curves were used to summarize overall test performance and assess study quality. Potential between-study heterogeneity was explored by subgroup analyses.

RESULTS

Fourteen of 330 initially identified reports were included in the meta-analysis. When we did not consider the unit of analysis, the pooled weighted SEN and SPE were 0.73 (95% confidence interval [CI]: 0.65-0.79) and 0.92 (95% CI: 0.88-0.94), respectively. In the patient-based data analysis, the pooled weighted SEN was 0.76 (95% CI: 0.65-0.84) and the pooled weighted SPE was 0.88 (95% CI: 0.82-0.92). In the MLN-based data analysis, the pooled SEN was 0.68 (95% CI: 0.56-0.78) and the pooled SPE was 0.95 (95% CI: 0.91-0.97).

CONCLUSIONS

Integrated PET/CT is a relatively accurate noninvasive imaging technique, with excellent specificity for MLN staging in patients with NSCLC. Nevertheless, current evidence suggests that we should not depend on the results of PET/CT completely for MLN staging in patients with NSCLC.

Negative predictive value of positron emission tomography and computed tomography for stage T1-2N0 non-small-cell lung cancer: a meta-analysis

BACKGROUND

Nodal staging of non-small-cell lung cancer (NSCLC) is crucial in evaluation of prognosis and determination of therapeutic strategy. This study aimed to determine the negative predictive value (NPV) of combined positron emission tomography and computed tomography (PET-CT) in patients with stage I (T1-2N0) NSCLC and to investigate the possible risk factors for occult nodal disease.

METHODS

Studies investigating the performance of PET in conjunction with CT in the nodal staging of stage I NSCLC were identified in the MEDLINE database. The initiative of standards for reporting of diagnostic accuracy (STARD) was used to ensure study quality. Pathologic assessments through mediastinoscopy or thoracotomy were required as the reference standard for evaluation of PET-CT accuracy. Stata-based meta-analysis was applied to calculate the individual and pooled NPVs.

RESULTS

Ten studies with a total of 1122 patients with stage I (T1-2N0) NSCLC were eligible for analysis. The NPVs of combined PET and CT for mediastinal metastases were 0.94 in T1 disease and 0.89 in T2 disease. Including both T1 disease and T2 disease, the NPVs were 0.93 for mediastinal metastases and 0.87 for overall nodal metastases. Adenocarcinoma histology type (risk ratio [RR], 2.72) and high fluorine-18 (18F) fluorodeoxyglucose (FDG) uptake in the primary lesion were associated with greater risk of occult nodal metastases.

CONCLUSIONS

Although overall occult nodal metastases in clinical stage T1-2N0 NSCLC is not infrequent, combined PET and CT provide a favorable NPV for mediastinal metastases in T1N0 NSCLC, suggesting a low yield from routine invasive staging procedures for this subgroup of patients.

Gold nanoparticles as novel agents for cancer therapy

Gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers. This review introduces the field of nanotechnology with a focus on recent gold nanoparticle research which has led to early-phase clinical trials. In particular, the pre-clinical evidence for gold nanoparticles as sensitisers with ionising radiation in vitro and in vivo at kilovoltage and megavoltage energies is discussed.

Non-small cell lung cancer: prognostic importance of positive FDG PET findings in the mediastinum for patients with N0-N1 disease at pathologic analysis

PURPOSE

To assess the prognostic implications of mediastinal positron emission tomographic (PET) findings in patients undergoing curative resection of non-small cell lung cancer (NSCLC) who have histologically negative mediastinal lymph nodes (LNs), with the hypothesis that positive findings at PET are prognostic even in patients with negative histologic findings in the LNs.

MATERIALS AND METHODS

Records of patients with a preoperative PET undergoing curative surgery, without adjuvant radiation, for pathologic T1-3N0-1 NSCLC at the University of North Carolina between 2000 and 2006 were reviewed as an institutional review board-approved HIPAA-compliant retrospective study. Ninety patients were evaluable (all histologically negative in mediastinum; 44 with both mediastinoscopy and surgery); 13 patients had positive mediastinal PET findings, and 77 had negative mediastinal PET findings. Local-regional and distant failure rates in patients with and those without mediastinal abnormalities at preoperative PET were compared by using logistic regression and log-rank tests.

RESULTS

Median follow-up was 54.3 months (range, 1-99 months). There were higher rates of local-regional (P = .001) and distant (P < .001) failure as well as death (P = .001) in patients with postive PET findings than in patients with negative findings. In multivariable analysis (adjusting for other prognostic factors), positive PET findings in the mediastinum remained prognostic for distant failure (P < .001, hazard ratio = 6.9) and were marginally prognostic for local-regional failure (P = .093, hazard ratio = 1.9).

CONCLUSION

Positive findings at preoperative PET in the mediastinum appear to have prognostic implications despite the mediastinal LNs being histologically negative. The high rate of local-regional and distant failure suggests that postoperative radiation therapy and/or chemotherapy may be particularly helpful in patients with positive mediastinal findings at preoperative PET.

Diagnostic and staging impact of radiotherapy planning FDG-PET-CT in non-small-cell lung cancer

BACKGROUND AND PURPOSE

To evaluate whether FDG-PET performed for radiotherapy (RT) planning can detect disease progression, compared with staging PET.

MATERIALS AND METHODS

Twenty-six patients with newly-diagnosed non-small-cell lung cancer underwent planning PET-CT for curative RT within 8 weeks (mean: 33±14days) of staging PET-CT. Progressive disease (PD) was defined as >25% increase in tumour size (transaxial) or volume, as delineated by SUV threshold of 2.5, or new sites (SUV>2.5).

RESULTS

The planning PET detected PD in 16 patients (61%), compared to four patients (15%) by CT component of PET-CT. The mean scan interval was longer in patients with progression: 40±12days, compared to 22±11days without progression. Planning PET detected PD in 13/17 (76%), 12/14 (86%) and 7/7 patients if the interval was ≥4, 5 and 6 weeks, respectively, compared with 3/9 patients if interval <4 weeks. Planning PET detected PD in primary metabolic volume in seven patients, 20 new nodal sites in 12 new nodal stations and nine patients, five extra-nodal sites in five patients. This resulted in upstaging in nine patients (35%): stage IIIA in three, IIIB in three and IV in three.

CONCLUSIONS

RT-planning FDG-PET can provide incremental diagnostic information and may impact on staging in a significant number of patients.

Predictive value of F-18 FDG PET/CT for malignant pleural effusion in non-small cell lung cancer patients

BACKGROUND

The purpose of this study was to evaluate the accuracy of F-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) imaging in the detection of malignant pleural effusion and pleural metastasis in patients with non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

We analyzed F-18 FDG PET/CT images of 33 lung cancer patients with pleural effusion. We used 2 categorical parameters to differentiate malignant from benign pleural effusion: i) quantitative parameters using maximum standardized uptake value (SUVmax of effusion and pleura, and the following ratios: lesion to aorta (L/Ao), to cerebellum (L/Cbl), to liver (L/Liv), to nonlesion (L/NL), and to primary lung cancer (L/Prim)) and ii) various parameters determined by PET and CT scans (uptake at the pleural region, Hounsfield unit, size, and morphology of any solid abnormality).

RESULTS

Malignant pleural effusions showed significantly higher L/Prim values than benign pleural effusions. The presence of pleural abnormality on CT and pleural region uptake on PET images were found to be significantly more frequent in cases of malignant pleural disease. These parameters could differentiate malignant and benign pleural effusion according to receiver operating characteristic (ROC) analyses. There were no statistical differences between L/Prim, pleural abnormality on CT, and pleural region uptake on PET images. Abnormal pleural region uptake on PET images was the most accurate parameter identifying malignant pleural effusion by logistic regression analysis.

CONCLUSIONS

Our results suggest that F-18 FDG PET/CT can be used as a reliable and noninvasive method for the differentiation of malignant and benign pleural disease in patients with NSCLC.

Revisions to the TNM staging of non-small cell lung cancer: rationale, clinicoradiologic implications, and persistent limitations

The International Association for the Study of Lung Cancer proposed changes to the 7th edition of the Tumor, Node, and Metastasis (TNM) staging manual of non-small cell lung cancer (NSCLC) to improve the prognostic relevance of its descriptors. These changes include the subdivision of T1 and T2 disease according to size cut points; reassignment of the T and M categories of same-lobe, ipsilateral, and contralateral malignant pulmonary nodules; reassignment of pleural disease to metastatic disease; and introduction of intra- and extrathoracic metastatic disease. Because of movement between T and M descriptors and resultant stage migration, new stage groupings that contain TNM subsets different from those of the previous edition were created. The new staging classification was created on the basis of statistical analysis of a large international database of cases of NSCLC. The new classification has many advantages; however, limitations remain. Problems with routine radiologic staging of NSCLC have not been addressed, the varied survival rates for patients with the different histologic subtypes is not reflected, the new classification is not compatible with the previous system, and application of treatment algorithms on the basis of evidence from the previous edition is less clear.

[Utility of PET/CT for mediastinal staging of non-small cell lung cancer in stage III (N2)]

PURPOSE

To evaluate the accuracy of integrated positron emission tomography with (18)F-fluoro-2-deoxy-D-glucose (FDG) and computed tomography (PET/CT) in mediastinal lymph node staging in patients with potentially operable (N2) non-small cell lung cancer (NSCLC) and to ascertain the role of invasive staging in verifying positron emission tomography (PET)/computed tomography (CT) results.

MATERIAL AND METHODS

A retrospective study of consecutive patients with pathologically-proven NSCLC and N2 staging by enhanced CT was performed. A PET/CT scan was performed for all the patients. Lymph node staging was pathologically confirmed when it was possible or by consensus in the Thoracic Cancer Committee. Sensitivity, specificity, negative predictive value and positive predictive value of PET/CT in N2 cases were determined.

RESULTS

A total of 34 patients with N2 by CT were evaluated. PET/CT showed N2 in 30 patients. Discrepancies were found in four patients, two patients were classified as N1 in PET/CT and two patients as N0. Lymph node staging was pathologically confirmed in 20 patients. No false positives were found in PET/CT study. Sensitivity was 94.7%, specificity and positive predictive values were 100% and negative predictive value was 50%.

CONCLUSIONS

Our data show that integrated PET/CT provides high sensitivity and positive predictive value in mediastinal nodal staging of NSCLC patients. Therefore, in patients with potentially resectable lung cancer, neoadjuvant chemotherapy candidate, mediastinoscopy could be reserved for restaging after induction therapy.

PET/CT imaging in different types of lung cancer: an overview

Lung cancer (LC) still represents one of the most common tumours in both women and men. PET/CT is a whole-body non-invasive imaging procedure that has been increasingly used for the assessment of LC patients. In particular, PET/CT added value to CT is mainly related to a more accurate staging of nodal and metastatic sites and to the evaluation of the response to therapy. Although the most common PET tracer for LC evaluation is 18F-FDG, new tracers have been proposed for the evaluation of lung neuroendocrine tumours (68Ga-DOTA-peptides, 18F-DOPA) and for the assessment of central nervous system metastasis (11C-methionine). This review focuses on the main clinical applications and accuracy of PET/CT for the detection of non-small cells lung cancer (NSCLC), broncho-alveolar carcinoma (BAC), small cells lung cancer (SCLC), lung neuroendocrine tumours (NET) and solitary pulmonary nodules (SPN).

Impact of whole-body ¹⁸F-fluorodeoxyglucose positron emission tomography on therapeutic management of non-small cell lung cancer

BACKGROUND AND OBJECTIVE

Accurate staging at the time of diagnosis is very important in deciding on the appropriate treatment for cancer patients. FDG PET indicates metabolic changes in cancer cells, enabling the early detection of lesions. This has the advantage of allowing more accurate staging than is possible with conventional staging tools, and has led to the incorporation of FDG PET in the initial work-up protocols for lung cancer patients. In this study, we evaluated the clinical impact of FDG PET as an initial staging tool, on the therapeutic management of patients with non-small cell lung cancer (NSCLC).

METHODS

Patients diagnosed with NSCLC by histopathology were retrospectively identified and both chest CT and FDG PET were performed for initial staging. Information was collected regarding the results of conventional versus FDG PET staging, and any resulting modifications of treatment were evaluated.

RESULTS

Among the 537 patients who were evaluated FDG PET resulted in upstaging of the tumour in 91 (17%) and downstaging of the tumour in 68 (13%). Consequently, therapeutic management was modified in 118 patients (22%). Furthermore, use of FDG PET resulted in the detection of a second primary cancer in six patients.

CONCLUSIONS

This study confirms that FDG PET has a considerable impact on the initial staging and therapeutic management of patients with NSCLC.

Lung cancer staging essentials: the new TNM staging system and potential imaging pitfalls

Lung cancer is the leading cause of cancer-related deaths worldwide, with a dismal 5-year survival rate of 15%. The TNM (tumor-node-metastasis) classification system for lung cancer is a vital guide for determining treatment and prognosis. Despite the importance of accuracy in lung cancer staging, however, correct staging remains a challenging task for many radiologists. The new 7th edition of the TNM classification system features a number of revisions, including subdivision of tumor categories on the basis of size, differentiation between local intrathoracic and distant metastatic disease, recategorization of malignant pleural or pericardial disease from stage III to stage IV, reclassification of separate tumor nodules in the same lung and lobe as the primary tumor from T4 to T3, and reclassification of separate tumor nodules in the same lung but not the same lobe as the primary tumor from M1 to T4. Radiologists must understand the details set forth in the TNM classification system and be familiar with the changes in the 7th edition, which attempts to better correlate disease with prognostic value and treatment strategy. By recognizing the relevant radiologic appearances of lung cancer, understanding the appropriateness of staging disease with the TNM classification system, and being familiar with potential imaging pitfalls, radiologists can make a significant contribution to treatment and outcome in patients with lung cancer.

Sarcoma

Sarcomas are a diverse group of malignancies originating in the connective tissue. The approach of a patient with a mass suspect for sarcoma starts with performing a biopsy to obtain tissue for evaluation by pathology. The main role of the current imaging modalities, in general, is to recognize patients with typically benign disease, in whom further invasive staging can be omitted, and select patients with a suspected malignancy, who should be referred for biopsy. Since soft tissue sarcoma tends to be large and heterogeneous, there is growing interest in using imaging modalities to guide these biopsies. Together with pathology, imaging modalities are the basis for accurate staging, evaluation of locoregional extent of the primary lesion, screening for occult metastases, evaluation of response to cancer treatment, and the detection of tumor recurrence. In this chapter, an overview is given of the use of 18F-FDG PET in these settings, its strengths as well as its limitations.

Impact of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) in lymph nodal and mediastinal lesions: a multicenter experience

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is an established procedure in lung cancer (LC) staging and in the diagnosis of mediastinal masses. Most of the experiences reported refer to single specialized centers where dedicated teams of endoscopists and pathologists perform the procedure. We report the EUS-FNA experience of a cooperation group involving clinicians and cytopathologists from three hospitals. Fifty-seven consecutive EUS-FNA of mediastinal nodes in LC patients, eight mediastinal and two subdiaphragmatic masses were collected in 3 years. EUS-FNA was performed by two endoscopists and three experienced pathologists. On-site evaluation was performed in all cases by the three cytopathologists. Lymph node negative cases underwent surgery, which confirmed the cytological diagnoses but also detected two false negatives. Four of the 10 EUS cytological diagnoses of mediastinal and subdiaphragmatic masses were histologically confirmed. All EUS diagnoses were blindly reviewed by three pathologists to assess intra and interpersonal reproducibility. FNA-EUS diagnoses were: 10 inadequate (17%), 10 negative (17%), 4 suspicious (7%) and 33 positive (59%). Diagnoses of mediastinal and subdiaphragmatic masses were: relapse of lung carcinoma (3), mesenchimal tumor not otherwise specifiable (3), gastrointestinal stromal tumor (GIST) (1), esophageal carcinoma (2) and paraganglioma (1). The sensitivity attained was 85% and the specificity 100%; revision of the slides demonstrated a significant diagnostic reproducibility of the three cytopathologists (P < 0.5). The sensitivity and specificity attained were similar to those reported in the literature suggesting that experienced cytopathologists and endoscopists from different institutions can employ the same procedure reaching comparable results.

Characterization of mediastinal lymphadenopathy with diffusion-weighted imaging

PURPOSE

To predict malignancy of mediastinal lymphadenopathy with diffusion-weighted imaging.

MATERIAL AND METHODS

A prospective study was conducted on 35 patients with mediastinal lymphadenopathy (28 malignant and seven benign nodes). They underwent echoplanar diffusion-weighted magnetic resonance imaging of the mediastinum with b-factors of 0, 300 and 600 s/mm(2). The apparent diffusion coefficient (ADC) values of the mediastinal lymph nodes were calculated. The ADC values were correlated with the biopsy results and statistical analysis was done. A value of P<.05 was considered significant.

RESULTS

The mean ADC value of malignant mediastinal lymphadenopathy (1.06±0.3×10(-3) mm(2)/s) was significantly lower (P=.001) than that of benign lymphadenopathy (2.39±0.7×10(-3) mm(2)/s). There was an insignificant difference in the ADC values between metastatic and lymphomatous mediastinal lymph nodes (P=.32) as well as within benign nodes (P=.07). When an ADC value of 1.85×10(-3) mm(2)/s was used as a threshold value for differentiating malignant mediastinal nodes from benign nodes, the best results were obtained with an accuracy of 83.9%, a sensitivity of 96.4%, a specificity of 71.4%, a negative predictive value of 95.2% and a positive predictive value of 77.1%. The area under the curve was 0.98.

CONCLUSION

Diffusion weighted magnetic resonance imaging is a promising noninvasive imaging modality that can be used for characterization of mediastinal lymphadenopathy and differentiation of malignant from benign mediastinal lymph nodes.

Dosimetric implications of the addition of 18 fluorodeoxyglucose-positron emission tomography in CT-based radiotherapy planning for non-small-cell lung cancer

Summary The aim of this study was to assess the impact of F-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) CT on radiotherapy planning parameters for patients treated curatively with radiotherapy for non-small-cell lung cancer (NSCLC). Five patients with stages I-III NSCLC underwent a diagnostic FDG-PET CT (dPET CT), planning FDG-PET CT (pPET CT) and a simulation CT (RTP CT). For each patient, three radiation oncologists delineated a gross tumour volume based on RTP CT alone, and fused with dPET CT and pPET CT. Standard expansions were used to generate PTVs, and a 3D conformal plan was created. Normal tissue doses were compared between plans. Coverage of pPET CT PTV by the plans based on RTP CT and dPET CT was assessed, and tumour control probabilities were calculated. Mean PTV was similar between RTP CT, dPET CT and pPET CT, although there were significant inter-observer differences in four patients. The plans, however, showed no significant differences in doses to lung, oesophagus, heart or spinal cord. The RTP CT plan and dPET CT plan significantly underdosed the pPET PTV in two patients with minimum doses ranging from 12 to 63% of prescribed dose. Coverage by the 95% isodose was suboptimal in these patients, but this did not translate into poorer tumour control probability. The effect of fused FDG-PET varied between observers. The addition of dPET and pPET did not significantly change the radiotherapy planning parameters. Although FDG-PET is of benefit in tumour delineation, its effect on normal tissue complication probability and tumour control probability cannot be predicted.

Impact of 18F-fluorodeoxyglucose positron emission tomography in the staging and treatment response assessment of extra-pulmonary small-cell cancer

The aim of this study was to retrospectively evaluate the value of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in extrapulmonary small-cell cancer (EPSCC). Patients with EPSCC who underwent PET for staging or response assessment between 1996 and 2007 were identified from a database. Patient records were reviewed. PET-based, and conventional staging and restaging results were compared. The binary staging classification of limited disease (LD) versus extensive disease (ED) was used. Patients with LD had tumours that could be encompassed within a tolerable radiation therapy (RT) volume. Of 33 eligible patients, 12 had staging PET scans, 11 had restaging scans and 10 had both. All known gross disease sites were FDG-avid. PET and conventional stage groupings were concordant in 21 of 22 cases. One patient was appropriately upstaged from LD to ED by PET. PET detected additional disease sites, without causing upstaging in three further patients. Restaging PET scans identified previously unrecognised persistent or progressive disease in 4 of 21 cases. In four further cases, persistent FDG uptake after treatment was either false positive (n = 2) or of uncertain (n = 2) aetiology. PPV was 100% for staging and 82% for restaging. In 8 of 43 imaging episodes (19%), PET appropriately influenced management in five cases by changing treatment intent from radical to palliative, and in three cases by altering the RT volume. PET has incremental value compared to conventional imaging for staging EPSCC, and may also be useful for restaging after therapy. PET influenced patient management in 19% of 43 imaging episodes.

[What is the role of FDG-PET in thoracic oncology in 2010?]

18F-Fluorodeoxyglucose-Positron Emission Tomography (FGD-PET) has been considered to have a major impact on the management of lung malignancies since the beginning of this century. Its value has been demonstrated by many publications, meta-analysis and European/American/Japanese recommendations. PET combined with computed tomography has provided useful information regarding the diagnosis and staging of lung cancer and allows for the delivery of adaptive radiotherapy. In its more common uses, PET has been shown to be cost-effective. With the widespread use of new radiotracers, PET will play an increasing role in the evaluation of response to treatment.

18-Fluorodeoxyglucose positron emission tomography as a tool for response prediction in solid tumours

Current response guidelines for the treatment of solid tumours are based on CT criteria. Over the last decades new techniques have emerged to evaluate cancer therapy. FDG-PET scanning is a more functional imaging technique, which can measure differences in metabolic activity. Although it has a low specificity, studies show that it can outperform classical CT scanning criteria. Especially in lung, breast and oesophageal cancer it can predict response earlier in the neo-adjuvant setting. This could reduce the use of ineffective cancer therapies, reducing costs and patient toxicity, and direct patients sooner towards effective therapy. The main problem with FDG-PET remains the difficulty in defining thresholds for response, as there is clearly a lack in large prospective randomized studies validating the use of FDG-PET in response guidelines.We give an overview of data on response prediction in solid tumours by the application of PET.

PET and PET-CT in radiation treatment planning for lung cancer

This review analyzes PET images in radiotherapy treatment planning for lung cancer patients and discusses the most controversial current issues. Computed tomography images are commonly used to assess location and extension of target volumes and organs at risk in radiotherapy treatment planning. Although PET is more sensitive and specific, contouring on PET images is difficult because tumor margins are indistinct, due to heterogeneous (18)fluorodeoxyglucose uptake distribution and limited spatial resolution. The best target delineation criteria have not yet been established. In non-small-cell lung cancer, PET appears to improve sparing of organs at risk and reduce the risk of toxicity; prescribed doses can be increased. Data are scarce on small-cell lung cancer.

Contribution of positron emission tomography in pleural disease

INTRODUCTION

Positron emission tomography (PET) now plays a clear role in oncology, especially in chest tumours. We discuss the value of metabolic imaging in characterising pleural pathology in the light of our own experience and review the literature.

BACKGROUND

PET is particularly useful in characterising malignant pleural pathologies and is a factor of prognosis in mesothelioma. Metabolic imaging also provides clinical information for staging lung cancer, in researching the primary tumour in metastatic pleurisy and in monitoring chronic or recurrent pleural pathologies.

CONCLUSIONS

PET should therefore be considered as a useful tool in the diagnosis of liquid or solid pleural pathologies.

PET/CT imaging: The incremental value of assessing the glucose metabolic phenotype and the structure of cancers in a single examination

PET/CT with the glucose analogue FDG is emerging as the most important diagnostic imaging tool in oncology. More than 2000 PET/CT scanners are operational worldwide and its unique role for diagnosing, staging, restaging and therapeutic monitoring in cancer is undisputed. Studies conducted in thousands of cancer patients have clearly indicated that the combination of molecular PET with anatomical CT imaging provides incremental diagnostic value over PET or CT alone. State of the art imaging protocols combine fully diagnostic CT scans with quality whole body PET surveys. The current review briefly describes the biological alterations of cancer cells that result in their switch to a strongly glycolytic phenotype. Different whole body imaging protocols are discussed. We summarize the evidence for the incremental value of PET/CT over CT and PET alone using imaging of sarcoma as an example. Following this section we discuss the performance of FDG-PET/CT imaging for staging, restaging and monitoring of head and neck cancer, solitary lung nodules and lung cancer, breast cancer, colorectal cancer, lymphoma and unknown primary tumors. Finally, the recently emerging evidence of a substantial impact of PET/CT imaging on patient management is presented.

An iterative technique to segment PET lesions using a Monte Carlo based mathematical model

PURPOSE

The need for an accurate lesion segmentation tool in 18FDG PET is a prerequisite for the estimation of lesion response to therapy, for radionuclide dosimetry, and for the application of 18FDG PET to radiotherapy planning. In this work, the authors have developed an iterative method based on a mathematical fit deduced from Monte Carlo simulations to estimate tumor segmentation thresholds.

METHODS

The GATE software, a GEANT4 based Monte Carlo tool, was used to model the GE Advance PET scanner geometry. Spheres ranging between 1 and 6 cm in diameters were simulated in a 10 cm high and 11 cm in diameter cylinder. The spheres were filled with water-equivalent density and simulated in both water and lung equivalent background. The simulations were performed with an infinite, 8/1, and 4/1 target-to-background ratio (T/B). A mathematical fit describing the correlation between the lesion volume and the corresponding optimum threshold value was then deduced through analysis of the reconstructed images. An iterative method, based on this mathematical fit, was developed to determine the optimum threshold value. The effects of the lesion volume and T/B on the threshold value were investigated. This method was evaluated experimentally using the NEMA NU2-2001 IEC phantom, the ACNP cardiac phantom, a randomly deformed aluminum can, and a spheroidal shape phantom implemented artificially in the lung, liver, and brain of patient PET images. Clinically, the algorithm was evaluated in six lesions from five patients. Clinical results were compared to CT volumes.

RESULTS

This mathematical fit predicts an existing relationship between the PET lesion size and the percent of maximum activity concentration within the target volume (or threshold). It also showed a dependence of the threshold value on the T/B, which could be eliminated by background subtraction. In the phantom studies, the volumes of the segmented PET targets in the PET images were within 10% of the nominal ones. Clinically, the PET target volumes were also within 10% of those measured from CT images.

CONCLUSIONS

This iterative algorithm enabled accurately segment PET lesions, independently of their contrast value.

[Comparison between PET(-FDG) and computed tomography in the staging of lung cancer. Consequences for operability in 94 patients]

INTRODUCTION

Lung cancer, a major application of FDG/PET-CT, has recently been introduced in daily practice in France. The authors retrospectively studied its impact on the management of this disease.

METHODS

The results of PET-CT and conventional assessment (brain imaging, chest and abdominal CT and possibly bone scintigraphy) were compared in 94 patients, referred for the staging of non-small cell lung cancer, or the assessment of a solitary lung lesion. The impact of thoracic lymph node involvement on the operability of patients was studied in 44 patients.

RESULTS

PET-CT revealed metastases in 20% of the patients without metastases found by conventional imaging and modified the stage of the disease in 28% of the cases. It changed the indication of surgical treatment in 19% of the cases and led to induction chemotherapy in two patients. In addition, two synchronous cancers were discovered. Regarding lymph node involvement, PET-CT remains of diagnostic value regardless of the scanner results.

CONCLUSION

The impact of PET-CT in assessing non-small cell lung cancer was confirmed in the authors' practice. Its interest and the consequences in some patients misclassified with conventional assessment have been demonstrated.

Endoscopic ultrasound-guided fine-needle aspiration when combined with positron emission tomography improves specificity and overall diagnostic accuracy in unexplained mediastinal lymphadenopathy and staging of non-small-cell lung cancer

BACKGROUND

The aim of this study was to assess the incremental value of endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) to positron emission tomography (PET) in the diagnosis of unexplained mediastinal lymphadenopathy and staging of non-small-cell lung cancer (NSCLC).

METHODS

Patients who had both EUS-guided FNA and PET were retrospectively identified from an EUS database at a tertiary hospital. All EUS-guided FNA were carried out by one endoscopist between August 2002 and April 2005, either for the diagnosis of unexplained mediastinal lymphadenopathy or for the staging of NSCLC. Results of PET and EUS were compared with histology. A true histological positive result was defined as histological involvement in either surgery (mediastinoscopy or resection) or EUS-guided FNA. A true histological negative result was defined as negative involvement at surgery (mediastinoscopy or resection).

RESULTS

Forty-nine patients who had both PET scanning and EUS-guided FNA for diagnosis of unexplained mediastinal lymphadenopathy or staging of NSCLC were identified. Of these, 33 (73% males, n = 24, age range = 44-78 years, mean = 62 years) had surgical confirmation of mediastinal lymph node pathology. In these patients, PET alone showed sensitivity, 95%; specificity, 90%; positive predictive value, 87%; negative predictive value, 90% and accuracy, 88%; whereas the addition of EUS-guided FNA increased the overall specificity and positive predictive value to 100%, with an overall accuracy of 97%.

CONCLUSIONS

This study suggests that EUS-guided FNA complements PET by improving the overall specificity and thereby the accuracy for diagnosis of unexplained mediastinal lymphadenopathy. It provides a minimally invasive technique to assess the mediastinum in patients with NSCLC and is particularly valuable in cases in which PET findings are equivocal.

Development of a generic thresholding algorithm for the delineation of 18FDG-PET-positive tissue: application to the comparison of three thresholding models

An iterative generic algorithm has been developed to compare three thresholding models used to delineate gross tumour volume on (18)F-FDG PET images. 3D volume was extracted and characteristic parameters were measured. Three fitting models using different parameters were studied: model 1 (volume, contrast), model 2 (contrast) and model 3 (SUV). The calibration was performed using a cylindrical phantom filled with hot spheres. To validate the models, two other phantoms were used. The calibration procedure showed a better fitting model for model 1 (R(2) from 0.94 to 1.00) than for model 3 (0.95) and model 2 (0.69). The validation study shows that model 3 yielded large volume measurement errors. Models 1 and 2 gave close results with no significant differences. Model 2 was preferred because it presents less error dispersion and needs fewer characteristic parameters, making it easier to implement. Our results show the importance of developing a generic algorithm to compare the performances of fitting models objectively and to validate results on other phantoms than the ones used during the calibration process to avoid methodological biases.

18F-FDG PET/CT for image-guided and intensity-modulated radiotherapy

Advances in technology have allowed extremely precise control of radiation dose delivery and localization within a patient. The ability to confidently delineate target tumor boundaries, however, has lagged behind. (18)F-FDG PET/CT, with its ability to distinguish metabolically active disease from normal tissue, may provide a partial solution to this problem. Here we review the current applications of (18)F-FDG PET/CT in a variety of disease sites, including non-small cell lung cancer, head and neck cancer, and pancreatic adenocarcinoma. This review focuses on the use of (18)F-FDG PET/CT to aid in planning radiotherapy and the associated benefits and challenges. We also briefly consider novel radiopharmaceuticals that are beginning to be used in the context of radiotherapy planning.

N2 disease in T1 non-small cell lung cancer

BACKGROUND

The optimal management strategy for mediastinal staging in early-stage non-small cell lung cancer (NSCLC) is not clearly defined. The true prevalence of mediastinal lymph node metastases (N2 disease) in resected pathologic T1 (pT1) NSCLC must be known to define the role of invasive mediastinal staging in these patients.

METHODS

Data of patients with pT1 lesions resected at Mayo Clinic between 1998 and 2006 were retrospectively reviewed. Patients with N2 disease were identified from pathology and operative reports. We reviewed demographics, radiologic data, and surgical procedures for those with pathologic T1 N2 NSCLC.

RESULTS

We identified 968 cases of pT1 lesions, 59 with pN2 disease (6.1%). For those with T1 N2 disease, the primary lung lesion was peripheral in 18 (31%) and central in 41 (69%). Of these, 36 had negative non-invasive mediastinal staging (3.7%) and were incidentally discovered. The most frequently affected lymph node station was 7 in 22 patients (37%), followed by 5,6 in 18 (31%). Mediastinoscopy found positive lymph nodes in 3 of 16 patients (19%) in which it was performed. Overall 5-year survival for pT1 N2 incidentally discovered during mediastinal lymph node dissection at the time of lung resection was 46% (95% confidence interval, 31% to 68%).

CONCLUSIONS

True pT1 NSCLC harbors a relatively low rate of N2 disease. The rate of occult N2 disease not observed on noninvasive preoperative mediastinal staging is even lower. For patients with T1 NSCLC and negative mediastinal imaging, routine mediastinoscopy results in a low yield of occult N2 disease discovery.

Differential diagnosis between (18)F-FDG-avid metastatic lymph nodes in non-small cell lung cancer and benign nodes on dual-time point PET/CT scan

OBJECTIVE

To clarify the difference of (18)F-FDG uptake kinetics between FDG-avid metastatic lymph nodes (LNs) in patients with non-small-cell lung cancer (NSCLC) and FDG-avid benign LNs associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation.

METHODS

The subjects were 134 FDG-avid metastatic LNs in 67 patients with NSCLC and 62 FDG-avid benign LNs in 61 patients with various lung disorders including NSCLC. PET/CT scan was performed at 2 time points (at 60 min and at 120 min) after intravenous injection of 4.4 MBq/kg (18)F-FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) were measured at each FDG-avid LN. The optimal parameter for differentiation was determined by the receiver-operating characteristic analysis.

RESULTS

Delayed SUVmax was increased compared with early SUVmax in 114 (85.0%) FDG-avid metastatic LNs and 42 (67.7%) FDG-avid benign LNs, with significant higher delayed SUVmax than early values (7.0 +/- 5.0 vs. 5.9 +/- 3.4; P < 0.0001, and 3.0 +/- 1.3 vs. 2.8 +/- 1.0; P < 0.05, respectively). Early and delayed SUVmax and %DeltaSUVmax in metastatic LNs were significantly higher than those in benign LNs (P < 0.0001). The optimal parameter for the differentiation was the combined use of early SUVmax > 3.0 or delayed SUVmax > 4.0, yielding sensitivity of 88.8%, specificity of 80.6%, accuracy of 86.2%, negative predictive value of 76.9%, and positive predictive value of 90.6%. It provided better results than the use of early SUVmax > 3.0 alone (P = 0.019) or the optimal parameter for %DeltaSUVmax (>5%) (P = 0.012). However, 12 (19.3%) benign LNs were indistinguishable from metastatic LNs.

CONCLUSIONS

Although dual-time point PET/CT scan enhances the difference of FDG uptake between FDG-avid metastatic and benign LNs and improves the differentiation when compared with a single scan, biopsy procedure may be still required for accurate assessment of LN status in patients with NSCLC and possible etiologies showing intensive FDG uptake in benign LNs.