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S. Tsim

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    ORAL 14 - Biology 2 (ID 112)

    • Event: WCLC 2015
    • Type: Oral Session
    • Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
    • Presentations: 1
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      ORAL14.01 - Early Contrast Enhancement as a Non-Invasive Objective Biomarker of Pleural Malignancy (ID 1687)

      16:45 - 18:15  |  Author(s): S. Tsim

      • Abstract
      • Presentation
      • Slides

      Despite imaging advances, differentiating pleural malignancy (PM) from benign pleural disease (BPD) remains challenging, particularly early-stage Malignant Pleural Mesothelioma (MPM), which can look similar to benign asbestos-related pleural effusion (BAPE). We report the diagnostic performance of a novel Magnetic Resonance Imaging (MRI) biomarker of PM - Early Contrast Enhancement (ECE).

      24 patients with suspected PM were recruited prospectively (January 2013-November 2014). All underwent contrast-enhanced Computed Tomography (CT) scanning and Thoracoscopy. 3-T Pleural MRI was performed prior to Thoracoscopy (median 4 (IQR 4–8) days). Imaging methodology was developed using patients 1-6. In 18 patients, T1-weighted 3D-spoiled-gradient-echo sequences were acquired coronally at baseline, 40 and 80 seconds and 4.5, 9 and 13.5 minutes after intravenous Gadobutrol contrast. Mean signal intensity (SI) of parietal pleura at each time-point was derived from 15 regions of interest placed by two respiratory physicians. ECE on the resulting SI/time curve was defined objectively as an early peak (at/before 4.5 minutes) and/or late fall in mean SI (Figure 1). CT and MRI scans were assessed for morphological features of PM by two thoracic radiologists. All analyses were blinded. Diagnostic performance was assessed using contingency tables. Inter- and intra-observer agreement was assessed using Cohen’s kappa statistic. Figure 1

      Median patient age was 73 (IQR 70–80) years. 75% (n=18) were asbestos-exposed. ECE was present in 10/11 patients with PM (MPM (10); lung cancer (1)). The false negative case had MPM. 1 MPM case was initially diagnosed with BAPE but reclassified as MPM after developing progressive PM, consistent with their initial MRI result (ECE present). ECE was absent in 6/7 patients with BPD (BAPE (4), fibrothorax (2), TB (1)). The false positive case had TB. Table 1 summarises diagnostic performance.

      Table 1: Diagnostic performance and reproducibility of ECE, CT morphology and MRI morphology in pleural malignancy
      Sensitivity (%) Specificity (%) Negative Predictive Value (%) Positive Predictive Value (%) Inter-observer agreement Intra-observer agreement
      CT Morphology 90 50 80 69 0.753 Not done
      MRI Morphology 91 71 83 83 0.727 Not done
      MRI Early Contrast Enhancement 91 86 86 91 0.766 1.000

      ECE appears a sensitive and specific objective biomarker of PM, out-performing subjectively-defined CT and MR morphology. SI/time curves for ECE assessment can be generated reproducibly in patients with minimal pleural thickening, suggesting potential utility as a non-invasive biomarker for the early detection of MPM or low-volume metastatic PM.

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