Delayed-Phase Enhancement for Evaluation of Malignant Pleural Mesothelioma on Computed Tomography: A Prospective Cohort Study

Abstract

Malignant pleural mesothelioma (MPM) can be challenging to discriminate from adjacent tissues on computed tomography (CT), leading to errors in tumor assessment. Here we demonstrate that by increasing the CT time delay for imaging acquisition after intravenous contrast administration, improved tumor enhancement and conspicuity is achieved. These data support further study of delayed phase contrast CT imaging in MPM. Background: Radiologic assessment of malignant pleural mesothelioma (MPM) on computed tomography (CT) imaging can be limited by similar attenuations of MPM and adjacent tissues. This can result in inaccuracies in defining the presence and extent of pleural tumor burden. We hypothesized that increasing the time delay for pleural enhancement will optimize discrimination between MPM and noncancerous tissues on CT. Here we conduct a prospective observational study to determine the optimal time delay for imaging MPM on CT. Patients and Methods: Adult MPM patients (n ¼ 15) were enrolled in this prospective exploratory imaging trial. Patients with < 1 cm MPM thickness, prior pleurectomy, pleurodesis, pleural radiotherapy, or antiangiogenic therapy were excluded. All patients underwent a dynamically-enhanced CT with multiple time delays (0 -10 minutes) after intravenous contrast administration. Tumor tissue attenuation was measured at each phase of enhancement. A qualitative assessment of tumor enhancement kinetics was also performed. The optimal phase of enhancement based on qualitative lesion conspicuity and quantitative tumor enhancement was then compared. Results: MPM tumor enhancement was quantitatively and qualitatively increased at time delays beyond the conventional time delay for thoracic CT imaging (40-60 seconds). Patient tumor enhancement kinetics, displayed as the fraction of maximal tumor tissue attenuation as a function of time, revealed an optimal time delay of 230 to 300 seconds after intravenous contrast administration. There was an association between degree of tumor enhancement and subjective lesion conspicuity. Conclusion: Optimal MPM contrast enhancement occurs at a later phase than typically acquired with conventional thoracic CT imaging.

Assessment of a single‐pass venous phase CT chest, abdomen and pelvis and dual‐energy CT in general oncology outpatients

“…[3][4][5][6][7] It is beneficial for assessing mesothelioma, pleural and chest wall metastases and complex effusions. [18][19][20] Our study demonstrated a significant increase in the visualisation of pleural masses on vCAP by Reader 1, with a trend to more clearly seen mediastinal nodes. The ability to visualise nodal enhancement characteristics including internal necrosis was considered particularly beneficial for assessment (Fig.…”

“…The venous phase in the chest allows time for pleural and pulmonary soft tissue masses and lymph nodes to enhance, with an additional reduction of perivenous artefact from the SVC and ascending aorta which can obscure mediastinal lymph nodes 3–7 . It is beneficial for assessing mesothelioma, pleural and chest wall metastases and complex effusions 18–20 . Our study demonstrated a significant increase in the visualisation of pleural masses on vCAP by Reader 1, with a trend to more clearly seen mediastinal nodes.…”

Implementation of a high-resolution, high-contrast magnetic resonance imaging protocol with extended delayed phases for peritoneal mesothelioma

“…Earlier studies have recommended a 5 min post-contrast delay, but longer delays were not evaluated ( 25 - 28 ). A CT study using delays of up to 10 min similarly found 4–5 min to be an optimal delay, but also that many lesions are still enhancing at that time ( 29 ). It could be posited that tumors that lead to high fibrotic response that can impede contrast diffusion, or those after neoadjuvant chemotherapy or radiation, might demonstrate similar delayed contrast enhancement.…”

Imaging of pleural disease

“…CT sensitivity is particularly low (27%) using CT pulmonary angiography and venous phase acquisition (69–90 s) is essential [ 18 ]. Peak contrast enhancement in a MPM tumour does not occur until 4.5 min on CT [ 19 ] and magnetic resonance imaging (MRI) [ 20 ], prompting delayed acquisition in some centres.…”