Contribution of positron emission tomography in pleural disease

Pleural Uptake Patterns in F18Fluorodeoxyglucose-Positron Emission Tomography (FDG-PET) Scans Improve the Identification of Malignant Pleural Effusions

BACKGROUND

The confirmation of malignant pleural effusions (MPE) requires an invasive procedure. Diagnosis can be difficult and may require repeated thoracentesis or biopsies. F18Fluorodeoxyglucose-Positron Emission Tomography (FDG-PET) can characterize the extent of malignant involvement in areas of increased uptake. Patterns of uptake in the pleura may be sufficient to obviate the need for further invasive procedures.

METHODS

This is a retrospective review of patients with confirmed malignancy and suspected MPE. Patients who underwent diagnostic thoracentesis with cytology and contemporaneous FDG-PET were identified for analysis. Some underwent confirmatory pleural biopsy. The uptake pattern on FDG-PET underwent blinded review and was categorized based on the pattern of uptake.

RESULTS

One hundred consecutive patients with confirmed malignancy, suspected MPE and corresponding FDG-PET scans were reviewed. MPE was confirmed in 70 patients with positive pleural fluid cytology or tissue pathology. Of the remaining patients, 15 had negative cytopathology, 14 had atypical cells and 1 had reactive cells. Positive uptake on FDG-PET was noted in 76 patients. The concordance of malignant histology and positive FDG-PET occurred in 58 of 76 patients (76%). Combining histologically confirmed MPE with atypical cytology, positive pleural FDG-PET uptake had a positive predictive value of 91% for MPE. An encasement pattern had a 100% PPV for malignancy.

CONCLUSION

Positive FDG-PET pleural uptake represents an excellent method to identify MPE, especially in patients with an encasement pattern. This may eliminate the need for additional invasive procedures in some patients, even when initial pleural cytology is negative.

[Medical thoracoscopy in respiratory medicine: The Liège University Hospital experience]

INTRODUCTION

The incidence of pleural disease continues to increase worldwide. Medical thoracoscopy remains the standard method for exploration of the pleural cavity.

METHOD

We report the retrospective evaluation, the efficacy and the observed complications in 1024 medical thoracoscopies undertaken in the University Hospital of Liège between 2000 and 2017.

RESULTS

In total, 100 pneumothoraces and 400 benign and 501 malignant pleural diseases were identified. The main indication for thoracoscopy remains the diagnosis of an exudative, lymphocytic pleural effusion of unknown aetiology after thoracocentesis. The diagnostic sensibility of thoracoscopy was 99.2% in distinguishing benign from malignant pleural disease. Talc pleurodesis was performed in 69.5% of the total population and in 66.1% of pleural effusions or thickening. Failure of pleurodesis was observed in 11% of the patients with recurrent pneumothorax and in 7.8% of neoplastic pleural effusion. We report a mortality of 0.6% in the 30 days post procedure, long duration of drainage in 8.3% and serious complications in 4.7%. In 22/1024 (2.1%) thoracoscopic evaluation was not feasible because of dense pleural fibrosis.

CONCLUSION

Medical thoracoscopy is a safe, well-tolerated procedure with high accuracy in the diagnostic and therapeutic management of pleural disease.

PET/CT and brain MRI role in staging NSCLC: prospective assessment of the accuracy, reliability and cost-effectiveness

Aim:

To determine whether PET/CT and brain MRI used in staging NSCLC can be accurate, reliable and cost-effective tools. NSCLC represents 80–85% of lung cancer and adequate information on the initial tumor staging is critical for planning an optimal therapeutic strategy.

Patients & methods:

Data from 30 newly diagnosed NSCLC patients in Greece were collected and prospectively recorded. Patients with potential resectable disease were evaluated to ensure that there are no detectable metastases that would rule out the possibility of a curative surgery.

Results:

Divergence occurred in 50% of cases of staging with CT or PET/CT alone, while metastases undetectable by the CT were revealed using PET/CT. Unnecessary thoracotomies were avoided by 10% of patients and another 10% was operated on after chemotherapy with a better prognosis.

Conclusion:

PET/CT and brain MRI combined are reliable for correct staging, reducing avoidable thoracotomies, morbidity rates and costs.

State-of-the-art: Radiological investigation of pleural disease

Pleural disease is common. Radiological investigation of pleural effusion, thickening, masses, and pneumothorax is key in diagnosing and determining management. Conventional chest radiograph (CXR) remains as the initial investigation of choice for patients with suspected pleural disease. When abnormalities are detected, thoracic ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) can each play important roles in further investigation, but appropriate modality selection is critical. US adds significant value in the identification of pleural fluid and pleural nodularity, guiding pleural procedures and, increasingly, as "point of care" assessment for pneumothorax, but is highly operator dependent. CT scan is the modality of choice for further assessment of pleural disease: Characterising pleural thickening, some pleural effusions and demonstration of homogeneity of pleural masses and areas of fatty attenuation or calcification. MRI has specific utility for soft tissue abnormalities and may have a role for younger patients requiring follow-up serial imaging. MRI and PET/CT may provide additional information in malignant pleural disease regarding prognosis and response to therapy. This article summarises existing techniques, highlighting the benefits and applications of these different imaging modalities and provides an up to date review of the evidence.

The role of computed tomography in assessing pleural malignancy prior to thoracoscopy

PURPOSE OF REVIEW

Computed tomography (CT) scanning is part of the routine diagnostic work up of patients with suspected pleural malignancy but has a wide variation in the reported sensitivity and specificity. This review was to appraise the recent literature on the utility of CT scanning.

RECENT FINDINGS

When investigating patients for suspected pleural malignancy, the sensitivity of a malignant CT report may be higher than previously reported (68%), but the specificity seems significantly lower (78%). The predictive value of CT scanning (on all patients with pleural effusions) may be increased using a CT scoring system. Recent meta-analyses of the utility of PET give differing opinions on the value of this imaging modality. Further work needs to be done to define its place in the diagnostic pathway.

SUMMARY

CT scoring systems may allow further risk stratification. However, a low negative predictive value of a 'negative' CT scan could lead to false reassurance and missed malignancy. PET/CT does not currently appear to add additional diagnostic value. Pulmonary emboli should be considered in all patients being investigated for clinically suspected malignant pleural disease. Respiratory physicians should be mindful of rare or unusual presentations.

PET/CT imaging in lung cancer: indications and findings

The use of PET/CT imaging in the work-up and management of patients with lung cancer has greatly increased in recent decades. The ability to combine functional and anatomical information has equipped PET/CT to look into various aspects of lung cancer, allowing more precise disease staging and providing useful data during the characterization of indeterminate pulmonary nodules. In addition, the accuracy of PET/CT has been shown to be greater than is that of conventional modalities in some scenarios, making PET/CT a valuable noninvasive method for the investigation of lung cancer. However, the interpretation of PET/CT findings presents numerous pitfalls and potential confounders. Therefore, it is imperative for pulmonologists and radiologists to familiarize themselves with the most relevant indications for and limitations of PET/CT, seeking to protect their patients from unnecessary radiation exposure and inappropriate treatment. This review article aimed to summarize the basic principles, indications, cancer staging considerations, and future applications related to the use of PET/CT in lung cancer.

Accuracy of fluorodeoxyglucose-PET imaging for differentiating benign from malignant pleural effusions: a meta-analysis

BACKGROUND

The role of fluorodeoxyglucose (FDG)-PET imaging for diagnosing malignant pleural effusions is not well defined. The aim of this study was to summarize the evidence for its use in ruling in or out the malignant origin of a pleural effusion or thickening.

METHODS

A meta-analysis was conducted of diagnostic accuracy studies published in the Cochrane Library, PubMed, and Embase (inception to June 2013) without language restrictions. Two investigators selected studies that had evaluated the performance of FDG-PET imaging in patients with pleural effusions or thickening, using pleural cytopathology or histopathology as the reference standard for malignancy. Subgroup analyses were conducted according to FDG-PET imaging interpretation (qualitative or semiquantitative), PET imaging equipment (PET vs integrated PET-CT imaging), and/or target population (known lung cancer or malignant pleural mesothelioma). Study quality was assessed using Quality Assessment of Diagnostic Accuracy Studies-2. We used a bivariate random-effects model for the analysis and pooling of diagnostic performance measures across studies.

RESULTS

Fourteen non-high risk of bias studies, comprising 407 patients with malignant and 232 with benign pleural conditions, met the inclusion criteria. Semiquantitative PET imaging readings had a significantly lower sensitivity for diagnosing malignant effusions than visual assessments (82% vs 91%; P = .026). The pooled test characteristics of integrated PET-CT imaging systems using semiquantitative interpretations for identifying malignant effusions were: sensitivity, 81%; specificity, 74%; positive likelihood ratio (LR), 3.22; negative LR, 0.26; and area under the curve, 0.838. Resultant data were heterogeneous, and spectrum bias should be considered when appraising FDG-PET imaging operating characteristics.

CONCLUSIONS

The moderate accuracy of PET-CT imaging using semiquantitative readings precludes its routine recommendation for discriminating malignant from benign pleural effusions.

Lung cancer coexisting with ipsilateral pleural effusion

SUMMARY 

Invasion beyond the elastic layer of the visceral pleura and/or diffuse pleural metastatic spread affects negatively survival in lung cancer. Presence of pleural effusion is also associated with poor prognosis, and image techniques can be of great help for diagnosis. When pleural fluid cytology is negative, thoracoscopy is advisable before attempting tumor resection, in order to detect unsuspected pleural metastases. If widespread pleural malignancy is confirmed, chemical pleurodesis using graded talc (with particles larger than 20 µm in diameter) is the best option, unless the lung is unable to re-expand. In this case, or when a previous pleurodesis has failed, or there is a short life expectancy, placement of a indwelling pleural catheter is the treatment of choice.

Diagnostic accuracy of 18F-FDG-PET and PET/CT in the differential diagnosis between malignant and benign pleural lesions: a systematic review and meta-analysis

RATIONALE AND OBJECTIVES

To systematically review and meta-analyze published data about the diagnostic accuracy of fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) and PET/computed tomography (CT) in the differential diagnosis between malignant and benign pleural lesions.

METHODS AND MATERIALS

A comprehensive literature search of studies published through June 2013 regarding the diagnostic performance of (18)F-FDG-PET and PET/CT in the differential diagnosis of pleural lesions was carried out. All retrieved studies were reviewed and qualitatively analyzed. Pooled sensitivity, specificity, positive and negative likelihood ratio (LR+ and LR-) and diagnostic odds ratio (DOR) of (18)F-FDG-PET or PET/CT in the differential diagnosis of pleural lesions on a per-patient-based analysis were calculated. The area under the summary receiver operating characteristic curve (AUC) was calculated to measure the accuracy of these methods. Subanalyses considering device used (PET or PET/CT) were performed.

RESULTS

Sixteen studies including 745 patients were included in the systematic review. The meta-analysis of 11 selected studies provided the following results: sensitivity 95% (95% confidence interval [95%CI]: 92-97%), specificity 82% (95%CI: 76-88%), LR+ 5.3 (95%CI: 2.4-11.8), LR- 0.09 (95%CI: 0.05-0.14), DOR 74 (95%CI: 34-161). The AUC was 0.95. No significant improvement of the diagnostic accuracy considering PET/CT studies only was found.

CONCLUSIONS

(18)F-FDG-PET and PET/CT demonstrated to be accurate diagnostic imaging methods in the differential diagnosis between malignant and benign pleural lesions; nevertheless, possible sources of false-negative and false-positive results should be kept in mind.