Imaging of Pleural Disease

The role of FDG PET-CT in differential diagnosis of pleural pathologies

OBJECTIVE

This study has aimed to evaluate the impact of (F18) Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography (FDG PET-CT) in the differential diagnosis of malignant and benign pleural lesions in patients with suspected malignant pleural mesothelioma (MPM).

MATERIAL AND METHODS

Fifty patients (32 females, 18 males; age range 24-79 years) with pleural thickening, fluid, plaques or calcification on previous CT scan were examined with FDG PET-CT. PET-CT imaging was obtained 1 h after FDG injection. In 12 patients, delayed imaging from the thoracic region was performed 2 h after injection. FDG uptake was evaluated visually and semiquantitively using standardized uptake value (SUV). FDG PET-CT findings were compared with histopathologic diagnosis.

RESULTS

Thirty-nine patients had increased FDG uptake in pleural lesions but PET-CT results were negative in 11 patients. When compared with histopathological results in FDG positive group, 34 patients had MPM, 5 had benign pathology; in FDG negative group 8 patients had benign pathology, 3 had MPM. Of patients with delayed imaging, 9 showed increased SUV but 3 had a decreased SUV on delayed images. Increased SUV group had 4 MPM, 5 benign pathology (3 chronic granulomatous inflammation, 2 benign asbestotic plaque). Decreased SUV group all had benign pathology (fibrosis, chronic inflammation, myofibrosis).

DISCUSSION

FDG PET-CT is a useful imaging modality in differential diagnosis of malignant and benign pleural lesions. Delayed imaging seems to be useful if there is a decrease in SUV suggesting a benign pathology but does not seem to contribute to the differential diagnosis if the SUV is increased.

Biopsy techniques for the diagnosis of mesothelioma

The incidence of mesothelioma continues to increase in the Western world and is likely to do so until 2011-2015. It commonly presents with breathlessness secondary to a pleural effusion, and whilst guidelines still advise thoracocentesis as the first line investigation, the sensitivity of this is low and a tissue diagnosis is usually required. Abrams needle biopsy also has a low diagnostic yield and high complication rate and is not recommended in guidelines on the investigation of mesothelioma. Computed tomography-guided biopsy or thoracoscopy both have a comparable sensitivity and low complication rates. Local anaesthetic thoracoscopy is increasingly used by respiratory physicians and has a comparable diagnostic sensitivity to Video-Assisted Thoracoscopic Surgery (VATS) without the need for a general anaesthetic. The requirement for prophylactic radiotherapy after pleural procedures in cases of mesothelioma is contentious, as the results from early trials suggesting it reduces tract seeding have been disputed by more recent trials.

Pitfalls in the evaluation of shortness of breath

This article illustrates the challenges practitioners face evaluating shortness of breath, a common emergency department complaint. Through a series of patient encounters, pitfalls in the evaluation of shortness of breath are reviewed and discussed.

Sonographic evaluation of unexplained pleural exudate: a prospective case series

BACKGROUND

Thoracic ultrasound may be helpful in differentiating between malignant and tuberculosis-associated pleural exudate. This study aimed to evaluate its utility in patients with unexplained pleural exudate.

METHODS

Consecutive patients were screened and pleural effusion was found in 278 patients. Pleural exudate was present in 106 patients and remained undiagnosed after biochemical and cytological evaluation in 40 patients (median age 58 years, 67% men) who then underwent detailed thoracic ultrasound for the presence of complex (septated or fibrous) or anechoic patterns. Pleural needle biopsy or thoracoscopy with histological evaluation were used for definitive diagnosis.

RESULTS

History, clinical characteristics and routine procedures including cytology were not helpful in differential diagnosis. Pleural specimens for histological evaluation were obtained from all 40 patients and confirmed tuberculosis in 12 patients, cancer in nine and nonspecific pleuritis in 19. Sonographic finding of a complex septal pattern was present only in patients with tuberculosis (positive predictive value 100%); anechoic appearance was suggestive of nonspecific pleuritis (positive predictive value 65%).

CONCLUSIONS

Thoracic ultrasound is a useful bedside method for differentiation of the etiology of pleural exudate. When a complex septal pattern is found, pleural needle biopsy should be the next diagnostic procedure, whereas with less complex pleural sonography findings other methods should be pursued.

Radiologic signs in thoracic imaging: case-based review and self-assessment module

OBJECTIVE

Chest imaging remains one of the most complicated sub-specialties of diagnostic radiology. The successful interpretation of thoracic imaging studies requires the recognition and understanding of the radiologic signs that are characteristic of many complex disease processes.

CONCLUSION

The educational objectives for this case-based self-assessment module are for the participant to exercise, self-assess, and improve his or her understanding of important thoracic radiologic signs that are useful in establishing the diagnosis of particular diseases of the chest.

Diagnosis and management of malignant pleural effusions

Malignant pleural effusions (MPEs) complicate the clinical course of patients with a broad array of malignancies, which are most often due to lymphomas or carcinomas of the breast, lung, gastrointestinal tract or ovaries. Patients may present with a MPE as the initial manifestation of a cancer or develop an effusion during the advanced phases of a known malignancy. In either circumstance, the median survival after presentation with a MPE is 4 months. Effusions may result from direct pleural invasion (MPE) or indirect effects (paraneoplastic effusions), such as impairment of fluid efflux from the pleural space by lymphatic obstruction or pleural effects of cancer radiation or drug therapy. Because only 50% of patients with cancer who develop a pleural effusion during their clinical course have a MPE, careful evaluation of the effusion to establish its aetiology is required to direct therapy. Management is palliative with interventions directed towards decreasing the volume of intrapleural fluid and the severity of associated symptoms.

Recent advances in the diagnosis and management of malignant pleural effusions

Malignant pleural effusions (MPEs) are an important complication for patients with intrathoracic and extrathoracic malignancies. Median survival after diagnosis of an MPE is 4 months. Patients can present with an MPE as a complication of far-advanced cancer or as the initial manifestation of an underlying malignancy. Common cancer types causing MPEs include lymphomas, mesotheliomas, and carcinomas of the breast, lung, gastrointestinal tract, and ovaries. However, almost all tumor types have been reported to cause MPEs. New imaging modalities assist the evaluation of patients with a suspected MPE; however, positive cytologic or tissue confirmation of malignant cells is necessary to establish a diagnosis. Even in the presence of known malignancy, up to 50% of pleural effusions are benign, underscoring the importance of a firm diagnosis to guide therapy. Rapidly evolving interventional and histopathologic techniques have improved the diagnostic yield of standard cytology and biopsy. Management of an MPE remains palliative; it is critical that the appropriate management approach is chosen on the basis of available expertise and the patient's clinical status. This review summarizes the pathogenesis, diagnosis, and management of MPE. Studies in the English language were identified by searching the MEDLINE database (1980-2007) using the search terms pleura, pleural, malignant, pleurodesis, and thoracoscopy.

Diagnostic work-up of pleural effusions

A wide range of diseases may be the cause of an accumulation of fluid in the pleural space. Pleural effusion is a major diagnostic problem, since the pleura is an inner cavity with no direct access. The aim of this review is to provide a practical approach to the investigation of the patient presenting with pleural effusion. This should help to accurately diagnose pleural effusion and keep time-consuming, but necessary, invasive investigations to the minimum.

Diagnosis and management of parapneumonic effusions and empyema

Approximately 1 million patients develop parapneumonic effusions (PPEs) annually in the United States. The outcome of these effusions is related to the interval between the onset of clinical symptoms and presentation to the physician, comorbidities, and timely management. Early antibiotic treatment usually prevents the development of a PPE and its progression to a complicated PPE and empyema. Pleural fluid analysis provides diagnostic information and guides therapy. If the PPE is small to moderate in size, free-flowing, and nonpurulent (pH, >7.30), it is highly likely that antibiotic treatment alone will be effective. Prolonged pneumonia symptoms before evaluation, pleural fluid with a pH <7.20, and loculated pleural fluid suggest the need for pleural space drainage. The presence of pus (empyema) aspirated from the pleural space always requires drainage. Fibrinolytics are most likely to be effective during the early fibrinolytic stage and may make surgical drainage unnecessary. If pleural space drainage is ineffective, video-assisted thoracic surgery should be performed without delay.