Multidetector CT imaging of pleura: comparison of two contrast infusion protocols

OBJECTIVES

Imaging of the pleura by multidetector CT (MDCT) can be challenging. There is no clear evidence or guidelines on contrast infusion parameters for imaging pleura. We compared two contrast protocols for assessing pleural pathology on MDCT.

METHODS

This was a prospective study in which consecutive patients with MDCT for suspected pleural disease on chest radiograph were randomised into two groups. The first group received 150 ml of intravenous contrast at a rate of 2.5 ml s(-1) and the second group received 100 ml at 2 ml s(-1). Images were acquired after a 60 s delay. Hounsfield units of the pleura, thoracic aorta, main pulmonary artery, portal vein and superior mesenteric artery were measured and analysed by two independent readers.

RESULTS

40 patients (20 in each group) who had pleural enhancement on MDCT were included for final analysis. The mean pleural enhancement value was 83 HU (Group A) vs 59 HU (Group B) (p = 0.0004). The mean aortic enhancement was 241 HU (A) vs 141 HU (B) (p<0.0001); main pulmonary artery enhancement was 208 HU (A) vs 139 HU (B) (p<0.0002); portal venous enhancement was 169 HU (A) vs 115 HU (B) (p<0.0001); and the superior mesenteric artery enhancement was 215 HU (A) vs 128 HU (B) (p<0.0001).

CONCLUSION

Enhancement of the pleura and major vessels was significantly higher in the group receiving more contrast at a greater infusion rate. This technique of a single scan through the entire pleural surface with a delayed acquisition is promising. When pleural disease is suspected, contrast infusion protocols should be modified to achieve the best results and clinicians should be encouraged to specifically request a "pleural CT".

Indications for thoracic ultrasound in chest medicine: an observational study

INTRODUCTION

Thoracic ultrasound (TUS) is increasingly used in chest medicine in secondary care. The indications for TUS are well known but less is known about their relative frequency. The purpose of this observational study was to describe the common indications for TUS and their relative frequency and the impact of TUS on management in a consecutive group of patients.

METHODS

80 consecutive inpatients and outpatients referred for TUS by the same operator in a UK National Health Service teaching hospital were included. Demographic data, clinical indication, findings and effect of TUS on clinical management were noted.

RESULTS

The most common clinical indication was to assess a pleural effusion in 60/80 cases (75%), but other indications included assessment of diaphragmatic function, pleural thickening and chest wall masses. TUS significantly altered patient management in 52/80 cases (65%): it resolved equivocal chest radiograph (CXR) findings and excluded pathology in 20/80 cases (25%), detected effusions not visible on CXR in 14/80 cases (18%), localised a safe site for medical thoracoscopy in 11/80 cases (14%) when not clinically apparent, and detected unexpected septation in 7/80 cases (9%). TUS guided pleural cytology diagnosed pleural fluid metastases in 9/22 cases aspirated (41%).

CONCLUSION

There are many clinical indications for TUS but the most common is pleural effusion assessment. TUS can diagnose inoperable pleural metastases, allow safe day case pleural intervention, exclude significant pleural pathology not visible on CXR, and triage further investigation.

Pseudocalcification on chest CT scan

Liquid ventilation with perfluorocarbons is used in severe respiratory failure that cannot be managed by conventional methods. Very little is known about the use of liquid ventilation in paediatric patients with respiratory failure and there are no reports describing the distribution and excretion of perfluorocarbons in paediatric patients with severe respiratory failure. The aim of this report is to highlight the prolonged retention of perfluorocarbons in a paediatric patient, mimicking pulmonary calcification and misleading the interpretation of the chest CT scan. A 10-year-old girl was admitted to our intensive care unit with severe respiratory failure due to miliary tuberculosis. Extracorporeal membrane oxygenation (ECMO) was used to support gas exchange and partial liquid ventilation (PLV) with perfluorodecalin was used to aid in oxygenation, lavage the lungs and clear thick secretions. The patient developed a pneumothorax (fluorothorax) on the next day and PLV was discontinued. Multiple bronchoalveolar lavages were performed to clear thick secretions. With no improvement in lung function over the next month a CT scan of the chest was performed. This revealed extensive pulmonary fibrosis and multiple high attenuation lesions suggestive of pulmonary calcification. To exclude perfluorodecalin as the cause for high attenuation lesions, a sample of perfluorodecalin was scanned to estimate the Hounsfield unit density, which was similar to the density of high attenuation lesions on chest CT scan. High-density opacification should be interpreted with caution, especially following liquid ventilation.

Image-guided pleural biopsy: diagnostic yield and complications

BACKGROUND

Pleural biopsy and cytology are standard procedures for the investigation of pleural disease. Recent medical literature has suggested that image-guided pleural biopsy shows improved sensitivity for the diagnosis of pleural malignancy, when compared with the more commonly performed reverse bevel needle biopsy such as Abrams' needle. In our centre there has been an increasing trend towards performing image-guided pleural biopsies, and to our knowledge there is no large published series documenting the complication rate and diagnostic yield.

METHODS

The radiology and pathology databases were searched for all image-guided [computed tomography (CT) and ultrasound (US)] pleural biopsies from January 2001 to December 2004. All imaging and histology were reviewed, and final diagnostic information about patients was obtained from the respiratory multidisciplinary team database and patient notes. A record was made of complications following biopsy, presence of pleura in the biopsy, and adequacy of tissue for histological diagnosis.

RESULTS

A total of 82 patients underwent 85 image-guided pleural biopsies over a 4-year period. 80 cases were performed under CT and five under US guidance. The rate of new pneumothorax detected by chest radiography was 4.7%. No patient required a chest drain or blood transfusion to treat complications. In 10 (12%) cases, there was inadequate tissue to reach a confident histological diagnosis and in eight (9%) of these, no pleura was present. Assuming all suspicious and inadequate biopsies are treated as benign, which is the worst case scenario, image-guided pleural biopsy has a sensitivity and specificity of 76% and 100%, respectively, for the diagnosis of malignant disease.

CONCLUSIONS

Image-guided pleural biopsy is a safe procedure with few associated complications and has a higher sensitivity than previously published series for reverse cutting needle biopsy in the diagnosis of malignant pleural disease.

Expression of CXCR6 and its ligand CXCL16 in the lung in health and disease

BACKGROUND

Chemokine receptors (CR) play an important role in T cell migration, but their contribution to lung trafficking is unclear.

OBJECTIVE

We hypothesized that if a particular CR was involved in T cell homing its expression would be enriched on lung T cells compared with peripheral blood T cells (PBT).

METHODS

We have measured the CR expression on BAL T cells from patients with sarcoid, other interstitial lung diseases (ILD), asthma and healthy volunteers.

RESULTS

Of 14 CR studied in sarcoid, CXCR6 expression was the most markedly increased in the lung compared with the blood, a finding that was also seen in ILD patients. A striking although lesser increase was also seen in asthmatics and healthy controls. Analysis of expression of the CXCR6 ligand, CXCL16, by immunohistochemistry suggested that alveolar macrophages (AM) were the major source of CXCL16 in the lung. AM expressed mRNA for CXCL16 and released nanogram quantities after adhesion to plastic as shown by RT-PCR, Western blotting and ELISA. Bronchoalveolar lavage (BAL) fluid from all subjects contained large amounts of CXCL16. The full-length CXCL16 was the predominant isoform in AM lysates, supernatants and BAL.

CONCLUSION

This data suggests that CXCR6 and CXCL16 may play a role in T cell recruitment to the lung.

Use of imaging in the management of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an increasingly prevalent tumour. The death rate associated with MPM is predicted to peak in the next 10 years, although radiologists and clinicians will be encountering cases for the next few decades. Contrast-enhanced CT is an established technique for evaluating suspected malignant pleural disease, but MPM can be reliably diagnosed only by histological sampling. However, even with adequate sampling and the use of immunocytochemistry, histological diagnosis is known to be difficult; definitive diagnosis may involve a combination of clinical presentation, radiological and histological appearances. Percutaneous biopsy is a promising technique for sampling the pleura. In view of its pattern of growth, MPM is a challenging disease to image by any method, and it behaves quite differently from lung cancer. This review aims to highlight the practical aspects of assessing malignant pleural mesothelioma.

Ultrasound guided cytological aspiration of supraclavicular lymph nodes in patients with suspected lung cancer

BACKGROUND

Lung cancer is the leading cause of death from cancer in the UK. Pathological diagnosis traditionally requires invasive procedures such as bronchoscopy, mediastinoscopy, or image guided biopsy. Ultrasound of the neck with fine needle aspiration cytology (FNAC) of enlarged but impalpable supraclavicular nodes has been used in patients with suspected lung cancer who have N2 or N3 disease on staging computed tomography (CT). If positive, this technique helps to both stage the patient and provide a cytological diagnosis.

METHODS

101 patients were enrolled prospectively over a 1 year period. FNAC was performed on all supraclavicular nodes over 5 mm in size using the capillary aspiration technique.

RESULTS

Sixty one of the 101 patients had enlarged supraclavicular nodes and underwent FNAC. The overall malignant yield was 45.5% of patients scanned and 75.4% of patients sampled. As a result of FNAC, 43 patients (42.6%) avoided more invasive procedures.

CONCLUSION

Ultrasound guided FNAC is a promising, relatively non-invasive technique for the staging and diagnosis of patients with lung cancer.

Does reporting of plain chest radiographs affect the immediate management of patients admitted to a medical assessment unit?

AIM

The purpose of our study was to investigate whether reporting of plain chest radiographs affects immediate management of patients admitted to a medical assessment unit.

MATERIALS AND METHODS

During a 3 month period we prospectively evaluated 200 patients who had a plain chest radiograph on admission. After the post on-call ward round, an independent medical specialist registrar reviewed the notes, retrieving relevant clinical details. The plain chest films were reported independently by a trainee radiologist and consultant, reaching a consensus report.

RESULTS

There was 93% agreement between trainee and consultant radiologists (95% CI=89-96%). Seventy percent had documented reports by the on-call medical team. There was disagreement between radiology and medical reports in 49% of reported films (95% CI=40-57%). The radiologist's report led to a direct change in the immediate management of 22 patients (11%).

CONCLUSION

Only 70% of films had documented reports in the clinical notes despite this being a legal requirement. Radiology reporting does cause a direct change in patient management. Chest radiographs of patients admitted to a medical admissions unit should be reported by a radiologist with the minimum of delay.