Radiologic-pathologic correlation of mesothelioma tumor volume

Our plain-English summary of Radiologic-pathologic correlation of mesothelioma tumor volume, by S.G. Armato, P. Li, A.N. Husain, et al (Lung Cancer, 2015).

The study

• Authors: S.G. Armato, P. Li, A.N. Husain, C. Straus, A. Khanwalkar, H.L. Kindler, W.T. Vigneswaran
• Journal: Lung Cancer
• Published: 2015;87(3):278-82
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Tumor volume promises to become a more important factor in patient management. Mesothelioma, with its unique morphology and complex growth pattern, presents a challenging target for tumor volumetrics derived from computed tomography (CT) scans. This study evaluated the validity of image-based mesothelioma tumor volume against the physical volume of the tumor bulk captured by the images.

Materials And Methods: Twenty-eight patients underwent CT scanning prior to pleurectomy/decortication with an intent to achieve a macroscopic complete resection. A radiologist manually outlined the tumor border in all CT sections in which tumor appeared in the pre-surgery scan. CT-based tumor volume was computed as the number of image pixels enclosed by all tumor outlines across all sections in the scan multiplied by the physical dimensions of the voxel of tissue captured by each image pixel. The gross tumor specimen volume was measured ex vivo through a water-displacement technique. Correlation between CT volume and pathology volume was calculated.

Results: A correlation coefficient r-squared value of 0.66 was found between CT-based tumor volume and gross tumor specimen volume. Differences between the mean volume (either CT volume or pathology volume) across tumors of different T stages did not achieve statistical significance.

Conclusion: Despite a modest correlation between CT-based tumor volume and gross tumor specimen volume, image-based volumetry for mesothelioma is not straightforward-perhaps, in part, due to the challenges of distinguishing tumor borders from adjacent structures and perhaps, in part, due to a complex pathologic reference standard.

Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

In plain English

This study compared two ways of measuring mesothelioma tumor volume in 28 patients who had extended pleurectomy/decortication at The University of Chicago Medical Center between February 2010 and August 2012. It did not study asbestos or any other exposure. Using CT scans taken before surgery, a single radiologist unaware of the pathology findings outlined the tumor by hand on every image where it appeared, and volume was calculated from these outlines. The surgically removed specimen was measured by water displacement. The two volumes correlated with an r-squared value of 0.66, and CT volume was smaller than specimen volume by a mean of 164.9 cubic centimetres. When the four cases with a specimen volume greater than 1000 ml were left out, r-squared fell to 0.18. Differences in either volume across tumor T stages were not statistically significant. The authors concluded that measuring mesothelioma volume from images is not straightforward. They suggested two possible reasons: tumor borders are hard to separate from nearby structures, and the specimen is a complex reference standard. Limitations they listed included use of one radiologist and few patients in each stage group.

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: Radiologic-pathologic correlation study comparing tumor volume measured by hand on pre-surgery CT scans with the volume of the surgically removed tumor specimen
• Who was studied: 28 patients (23 males, 5 females, aged 56 to 89, median 70; 17 epithelioid and 11 biphasic tumors) who had extended pleurectomy/decortication at The University of Chicago Medical Center between February 2010 and August 2012 and had a pre-surgery CT scan
• Exposure: Not studied: the article concerns measurement of tumor volume and does not examine asbestos or other exposures
• Main results:
  • Across all 28 patients, CT-based tumor volume and gross tumor specimen (pathologic) volume correlated with an r-squared value of 0.66
  • CT volume was systematically smaller than pathologic volume, by a mean of 164.9 cubic centimetres
  • Excluding the four cases with pathologic volume greater than 1000 ml lowered r-squared to 0.18. Removing only the single case with the largest pathologic volume lowered it to 0.55
  • In the 18 patients whose specimen was also weighed, specimen mass and specimen volume correlated with an r-squared value of 0.89
  • Mean pathologic volume was 25 ml for stage 1 (1 patient), 599.4 ml for stage 2 (8 patients), 644.4 ml for stage 3 (9 patients) and 725 ml for stage 4 (10 patients)
  • Mean CT volume was 7.03 cc for stage 1, 336.18 cc for stage 2, 510.96 cc for stage 3 and 595.65 cc for stage 4
  • Comparing T1 and T2 patients with T3 and T4 patients, the difference in mean volume was not statistically significant: p = 0.17 for CT volume and p = 0.43 for pathology volume
  • In the 15 patients scanned at most 30 days before surgery, r-squared was 0.66. In the 7 patients scanned at most 14 days before surgery, it was 0.89. The authors said these subsets were too small for meaningful conclusions
• The authors' conclusion: The authors concluded that image-based volume measurement for mesothelioma is not straightforward, perhaps partly because tumor borders are hard to distinguish from adjacent structures and partly because the pathologic reference standard is complex
• Limitations the authors state:
  • A single radiologist outlined all tumors, so variability between different readers was not assessed
  • The small number of patients in each T stage limits conclusions from comparisons between stage subgroups
  • Tumor seen on CT might not be reachable during surgery, so the removed specimen might not match what the scan shows
  • Distortion of the specimen outside the body could affect the water-displacement volume measurement
  • The removed specimen inevitably included non-tumor tissue such as fat and diaphragm
  • Pathologic volume was measured only in 25 ml steps, much coarser than CT measurement
  • The time between the pre-surgery CT scan and surgery (3 to 133 days) was not controlled

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Pleurectomy/Decortication (P/D), Pathology, Statistical Significance.

Related studies

• From the archives of the AFIP. Malignant pleural mesothelioma: radiologic-pathologic correlation — B.H. Miller, M.L. Rosado-de-Christenson, et al. (1996)
• Benign Multicystic Peritoneal Mesothelioma: AIRP Best Cases in Radiologic-Pathologic Correlation — R. Lee, A. Tong, et al. (2016)
• Serum soluble mesothelin concentrations in malignant pleural mesothelioma: relationship to tumor volume, clinical stage and changes in tumor burden — J. Creaney, R.J. Francis, et al. (2011)
• Solitary fibrous tumor of the orbit: CT and pathologic correlation — S. Festa, H.J. Lee, et al. (1999)
• Specimen weight and volume: important predictors of survival in malignant pleural mesothelioma — D.Y. Kircheva, A.N. Husain, et al. (2016)
• Lung volume measurements as a surrogate marker for patient response in malignant pleural mesothelioma — Z.E. Labby, S.G. Armato, et al. (2013)

Browse more research in Lung Cancer, or return to medical research.