Spectral CT may help inexperienced radiologists define malignant pleural diseases

Spectral CT with iodine mapping helps differentiate benign pleural metastatic tumors from cancerous lesions, reported authors of a Jan. 15 Radiology study. The iodine overlays particularly helped less-experienced radiologists.

“The occurrence of parietal pleural metastases is generally associated with a poor prognosis and often shifts treatment to palliative care,” wrote Simon Lennartz, of University Hospital Cologne in Germany, and colleagues. “Thus, detection of parietal pleural thickening and accurate determination of lesion enhancement after contrast agent administration is important.”

Included in the study were 84 patients (mean age 66) who had received contrast-enhanced late venous phase spectral chest CT. Comparing conventional CT against spectral CT-generated iodine overlay images and quantitative iodine maps, the latter achieved better sensitivity (96 percent versus 83 percent) and improved specificity (84 percent versus 63 percent).

“These preliminary observations show that iodine overlay images and quantitative iodine maps provided by using spectral CT can help the observer to differentiate noncalcified benign pleural lesions from pleural carcinomatosis with higher sensitivity and specificity than with conventional CT,” the authors wrote.

Additionally, Lennartz and colleagues found the spectral-based reconstructions raised the performance of inexperienced radiologists (two years of experience) near the levels achieved by readers with five and 14 years of thoracic experience. Averaged over all reviewers, iodine overlays increased sensitivity to 96 percent from 83 percent, and specificity jumped to 84 percent from 63 percent.

The authors noted their research was an ad hoc retrospective pilot study, and that “the quantitative threshold for lesion differentiation still needs to be validated.”

Two authors of a related editorial, including Kyung Soo Lee of Sungkyunkwan University School of Medicine in Seoul, Korea, described the study as “well done,” and noted the iodine map improves diagnostic performance by providing more precise enhancement information of pleural diseases.

Lee and colleagues wrote integrating all information from enhanced spectral CT are required to differentiate pleural carcinomatosis from benign pleural disease, but noted further research is crucial.

“A prospective validation study with a large cohort and diverse pleural diseases would help to prove the real value of spectral CT in evaluating diffuse pleural diseases,” they concluded.