The diagnostic performance of routinely acquired and reported computed tomography imaging in patients presenting with suspected pleural malignancy

Our plain-English summary of The diagnostic performance of routinely acquired and reported computed tomography imaging in patients presenting with suspected pleural malignancy, by S. Tsim, D.B. Stobo, L. Alexander, et al (Lung Cancer, 2017).

The study

• Authors: S. Tsim, D.B. Stobo, L. Alexander, C. Kelly, K.G. Blyth
• Journal: Lung Cancer
• Published: 2017;103:38-43
• Cited by: 43 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: Contrast-enhanced computed tomography (CT) provides essential cross-sectional imaging data in patients with suspected pleural malignancy (PM). The performance of CT in routine practice may be lower than in previously reported research. We assessed this relative to 'real-life' factors including use of early arterial-phase contrast enhancement (by CT pulmonary angiography (CTPA)) and non-specialist radiology reporting.

Materials And Methods: Routinely acquired and reported CT scans in patients recruited to the DIAPHRAGM study (a prospective, multi-centre observational study of mesothelioma biomarkers) between January 2014 and April 2016 were retrospectively reviewed. CT reports were classified as malignant if they included specific terms e.g. "suspicious of malignancy", "stage M1a" and benign if others were used e.g. "indeterminate", "no cause identified". All patients followed a standard diagnostic algorithm. The diagnostic performance of CT (overall and based on the above factors) was assessed using 2×2 Contingency Tables.

Results: 30/345 (9%) eligible patients were excluded (non-contrast (n=13) or non-contiguous CT (n=4), incomplete follow-up (n=13)). 195/315 (62%) patients studied had PM; 90% were cyto-histologically confirmed. 172/315 (55%) presented as an acute admission, of whom 31/172 (18%) had CTPA. Overall, CT sensitivity was 58% (95% CI 51-65%); specificity was 80% (95% CI 72-87%). Sensitivity of CTPA (performed in 31/315 (10%)) was lower (27% (95% CI 9-53%)) than venous-phase CT (61% (95% CI 53-68%) p=0.0056). Sensitivity of specialist thoracic radiologist reporting was higher (68% (95% CI 55-79%)) than non-specialist reporting (53% (95% CI 44-62%) p=0.0488). Specificity was not significantly different.

Conclusion: The diagnostic performance of CT in routine clinical practice is insufficient to exclude or confirm PM. A benign CT report should not dissuade pleural sampling where the presence of primary or secondary pleural malignancy would alter management. Sensitivity is lower with non-thoracic radiology reporting and particularly low using CTPA.

Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

In plain English

This study examined how well CT scans read in everyday hospital care detected pleural malignancy (cancer in the lung lining, including mesothelioma and spread cancers). The authors reviewed CT reports for 315 patients recruited from January 2014 to April 2016 at 4 West of Scotland centres to DIAPHRAGM, a mesothelioma blood-marker study; 39% were asbestos-exposed. Each report's wording was classed malignant or benign and compared with the final diagnosis. 195 patients (62%) had pleural malignancy, 59 of them mesothelioma. CT flagged 58% of malignancies (sensitivity; 95% confidence interval 51–65%) and correctly cleared 80% of benign cases (specificity; 95% CI 72–87%). Almost half of patients with malignancy had a benign CT report. Sensitivity was 27% (95% CI 9–53%) for the 31 CT pulmonary angiograms versus 61% (95% CI 53–68%) for the 284 venous-phase scans. It was 68% (95% CI 55–79%) with specialist thoracic radiologists versus 53% (95% CI 44–62%) with other radiologists. Specificity differences were not statistically significant. The authors concluded that routine CT is insufficient to exclude or confirm pleural malignancy. They noted that reports were classified retrospectively and the angiogram group was small.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective cohort study of routinely acquired and reported CT scans in patients prospectively recruited to the DIAPHRAGM observational study. CT report classifications were compared with the final diagnosis using 2 × 2 contingency tables.
• Who was studied: 315 patients with suspected pleural malignancy (unilateral pleural effusion or pleural mass), recruited consecutively to DIAPHRAGM at 4 centres in the West of Scotland between January 2014 and April 2016. Of 345 eligible patients, 30 were excluded. 65% were male, 39% (123/315) were asbestos-exposed, and the median age was 74 years.
• Exposure: The factor studied was contrast-enhanced CT imaging, not asbestos exposure. 31 of 315 scans were CT pulmonary angiograms (arterial phase) and 284 were venous-phase scans. 77 radiologists reported the scans; 17 were thoracic radiologists, who reported 115 of the 315 scans. The article states that 39% of patients were asbestos-exposed but gives no fiber types or exposure details.
• Main results:
  • Final diagnoses: 195 of 315 patients (62%) had pleural malignancy, and 90% (176/195) of these were confirmed by cytology or histology. Among the 315 patients, 59 (19%) had mesothelioma and 23 (7%) had benign asbestos-related pleural effusion.
  • In all 315 patients, CT had a sensitivity of 58% (95% CI 51–65%), a specificity of 80% (95% CI 72–87%), a positive predictive value of 83% (95% CI 75–89%) and a negative predictive value of 54% (95% CI 46–61%).
  • Almost half of the patients with pleural malignancy had a benign CT report: 81 of 195, according to Table 3.
  • Sensitivity was 27% (95% CI 9–53%) for CT pulmonary angiograms (n = 31), significantly lower than 61% (95% CI 53–68%) for venous-phase CT (n = 284), p = 0.0056. The negative predictive value of CT pulmonary angiograms was 40% (95% CI 20–63%).
  • Specificity was 69% (95% CI 38–90%) for CT pulmonary angiograms and 82% (95% CI 73–88%) for venous-phase CT. This difference was not statistically significant (p = 0.2712).
  • Sensitivity was 68% (95% CI 55–79%) when a thoracic radiologist reported the scan (n = 115), compared with 53% (95% CI 44–62%) for non-thoracic radiologists (n = 200), p = 0.0488.
  • Specificity was 75% (95% CI 61–86%) for thoracic radiologists and 84% (95% CI 73–92%) for non-thoracic radiologists. This difference was not statistically significant (p = 0.2184).
  • 108 of 315 patients (34%) had venous-phase CT reported by a thoracic radiologist ('optimal' conditions). In this group, sensitivity was 69% (95% CI 56–80%) and specificity was 73% (95% CI 58–85%).
• The authors' conclusion: The authors concluded that CT performance in routine clinical practice is insufficient to exclude or confirm pleural malignancy. They stated that sensitivity is lower with non-thoracic radiology reporting and particularly low with CT pulmonary angiography, and that a benign CT report should not dissuade pleural sampling where pleural malignancy would alter management.
• Limitations the authors state:
  • Patients were recruited prospectively, but each CT report was classified as malignant or benign retrospectively.
  • The minimum follow-up required for inclusion was only 6 months. The authors stated this could theoretically underestimate the true mesothelioma rate, since patients with benign asbestos pleural effusion are normally followed for at least 2 years.
  • The CT pulmonary angiogram results rest on small numbers with wide confidence intervals.
  • Too few patients were imaged under sub-optimal conditions (CT pulmonary angiograms read by non-thoracic radiologists, n = 24) to compare them meaningfully with optimal conditions.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: CT Scan, Diaphragm, Mesothelioma, Biomarker.

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• Diagnostic Value of Computed Tomography Imaging Features in Malignant Pleural Mesothelioma — M. Fortin, E. Cabon, et al. (2020)
• Early Contrast Enhancement: A novel magnetic resonance imaging biomarker of pleural malignancy — S. Tsim, C.A. Humphreys, et al. (2018)
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