Conspicuity of malignant pleural mesothelioma in contrast enhanced MDCT - arterial phase or late phase?

Our plain-English summary of Conspicuity of malignant pleural mesothelioma in contrast enhanced MDCT - arterial phase or late phase?, by L. Luerken, P.L. Thurn, F. Zeman, et al (BMC Cancer, 2021).

The study

• Authors: L. Luerken, P.L. Thurn, F. Zeman, C. Stroszczynski, O.W. Hamer
• Journal: BMC Cancer
• Published: 2021;21(1):1144
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: To determine if late phase is superior to arterial phase intraindividually regarding conspicuity of MPM in contrast enhanced chest MDCT.

Methods: 28 patients with MPM were included in this retrospective study. For all patients, chest CT in standard arterial phase (scan delay ca. 35 s) and abdominal CT in portal venous phase (scan delay ca. 70 s) was performed. First, subjective analysis of tumor conspicuity was done independently by two radiologists. Second, objective analysis was done by measuring Hounsfield units (HU) in tumor lesions and in the surrounding tissue in identical locations in both phases. Differences of absolute HUs in tumor lesions between phases and differences of contrast (HU in lesion - HU in surrounding tissue) between phases were determined. HU measurements were compared using paired t-test for related samples. Potential confounding effects by different technical and epidemiological parameters between phases were evaluated performing a multiple regression analysis.

Results: Subjective analysis: In all 28 patients and for both readers conspicuity of MPM was better on late phase compared to arterial phase. Objective analysis: MPM showed a significantly higher absolute HU in late phase (75.4 vs 56.7 HU, p < 0.001). Contrast to surrounding tissue was also significantly higher in late phase (difference of contrast between phases 18.5 HU, SD 10.6 HU, p < 0.001). Multiple regression analysis revealed contrast phase and tube voltage to be the only significant independent predictors for tumor contrast.

Conclusions: In contrast enhanced chest-MDCT for MPM late phase scanning seems to provide better conspicuity and higher contrast to surrounding tissue compared to standard arterial phase scans.

© 2021. The Author(s).

In plain English

This retrospective study from the University Medical Center Regensburg, Germany, looked at CT scans of 28 patients with malignant pleural mesothelioma. Each patient had a chest scan taken early after a contrast injection (arterial phase, about 35 seconds) and an abdominal scan taken later (portal venous or 'late' phase, about 70 seconds) that also showed the tumor. The study asked how well the tumor stood out on each scan. It did not study asbestos exposure, though it recorded that exposure was confirmed in 16 patients, ruled out in 1 and unknown in 11. Two radiologists rated the tumor as better visible on the late phase in all 28 patients. Tumor density averaged 56.7 HU (Hounsfield units, a CT density scale) early and 75.4 HU late. The contrast between tumor and nearby tissue was 18.5 HU greater on the late phase (p less than 0.001). Contrast phase and tube voltage were the only significant predictors of tumor contrast. The authors concluded that late phase imaging may improve detection of this tumor on chest CT. They noted the small number of patients and that exact scan delays were not documented.

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 study comparing two CT contrast phases within the same patients (each patient's arterial phase scan against the same patient's late phase scan)
• Who was studied: 28 patients with malignant pleural mesothelioma (24 male, 4 female; average age at diagnosis 66.3 years). They were selected from 760 patients identified among CT scans done at a university medical center in Regensburg, Germany, between January 1, 2003 and 'April 31, 2015' (date as printed).
• Exposure: The comparison was between CT contrast timing: a standard arterial phase chest CT (scan delay about 35 s) and a portal venous (late) phase abdominal CT (scan delay about 70 s) covering the tumor. Asbestos exposure was recorded but not studied: confirmed in 16 patients (57.1%), ruled out in 1 (3.6%), no reliable information in 11 (39.3%). No fiber types are named.
• Main results:
  • Subjective rating: in all 28 patients, both radiologists rated the mesothelioma as better visible on the late phase than on the arterial phase.
  • Tumor density averaged 56.7 HU (SD 18.1) in the arterial phase and 75.4 HU (SD 22.9) in the late phase. The difference was 18.6 HU (SD 10.1), p less than 0.001.
  • Density of the adjacent non-tumor soft tissue barely changed between phases: average difference 0.1 HU (SD 5.6), p = 0.92.
  • The contrast between tumor and adjacent tissue was on average 18.5 HU (SD 10.6) greater in the late phase than in the arterial phase, p less than 0.001.
  • In the regression analysis, the adjusted difference in contrast between phases was 16.1 HU (95% CI 14.0 to 18.2), p less than 0.001.
  • Contrast phase and tube voltage were the significant independent predictors of tumor contrast. Tube-current-time-product and slice thickness were not significant.
  • Histological subtype, chemotherapy before the scans, and gender were not significant predictors of tumor contrast.
• The authors' conclusion: The authors concluded that late phase imaging may improve the diagnostic accuracy for detecting malignant pleural mesothelioma on chest CT, and that changing the routine arterial phase protocol should be discussed when this disease is suspected.
• Limitations the authors state:
  • The number of cases was small (n = 28), even though 12 years of records were searched.
  • The strict selection criteria further limited the number of eligible patients.
  • Exact scan delays were not documented, and imaging protocols may have changed over the 12-year period.
  • Different contrast protocols could not be evaluated, because most examinations used a single contrast injection.
  • The study could not examine whether better tumor visibility on late phase imaging affects patient prognosis.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Confounding.

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