The Egyptian Journal of Radiology and Nuclear Medicine xxx (2016) xxx–xxx Contents lists available at ScienceDirect The Egyptian Journal of Radiology and Nuclear Medicine journal homepage: www.sciencedirect.com/locate/ejrnm Original Article Value of contrast CT in combination with PET/CT in mesothelioma staging: Optimal protocol for initial assessment Mohamed Houseni a,⇑, Amr Osama b, Dalia Ibrahim Mohamed b, Shahinda Salem c a Department of Diagnostic and Interventional Medical Imaging, National Liver Institute, Menoufia University, Shibin El-Koum, Egypt Radiology Department, Faculty of Medicine, Cairo University, Cairo, Egypt c Nuclear Medicine Unit, Department of Clinical Oncology and Nuclear Medicine, Faculty of Medicine, Cairo University, Cairo, Egypt b a r t i c l e i n f o Article history: Received October 2016 Accepted 16 December 2016 Available online xxxx Keywords: Mesothelioma staging 18F-FDG-PET PET/CT Contrast CT a b s t r a c t Purpose: To assess the value of contrast enhanced CT (ceCT) when added to positron emission tomography combined with the standard low-dose non-contrast CT (PET/CT) protocols for staging patients with malignant pleural mesothelioma (MPM) Methods: Retrospective analysis of 47 patients with pathologically proved MPM All patients underwent PET/CT with low dose CT followed by ceCT PET/CT and ce-CT were evaluated separately then in combination All the results were validated either by histopathology and/or clinical-radiological follow-up Staging was performed based on TNM system Results: For T-stage, the sensitivities for PET/CT, ceCT and combined PET/CT-ceCT were 89.1%, 86.9%, and 97.5%, respectively, p = 0.04 Regarding nodal stage, the sensitivity, specificity and accuracy for PET/CT were 88.5%, 90.5%, and 89.4%; for ceCT 73.1%, 95.2% and 82.9%; and for PET/CT-ceCT 96.2%, 95.2% and 95.7%, respectively PET/CT-ceCT significantly associated with the sensitivity, p = 0.05 Considering the metastatic disease, the sensitivity, specificity and accuracy for PET/CT were 81.3%, 96.8%, and 91.5%; for ceCT 56.3%, 90.3% and 78.7%; and for PET/CT-ceCT 93.8%, 96.8% and 95.7%, respectively PET/CTceCT significantly improved the sensitivity (p = 0.03) and accuracy (p = 0.02) Furthermore, combined PET/CT-ceCT significantly identified patients not suitable for surgery Conclusion: The addition of ceCT to PET/CT protocol has significantly contributed to the staging of MPM Ó 2016 The Egyptian Society of Radiology and Nuclear Medicine Production and hosting by Elsevier This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/) Introduction Malignant pleural mesothelioma is an aggressive cancer It mainly affects the parietal pleura and may invade local structures Treatment may involve a combination of radical surgery, chemotherapy and radiation [1] Accurate staging of mesothelioma is paramount to choose the most efficient treatment strategy The most significant step in staging and re-staging is to identify patients who may get benefit from surgery [2] Based on The European Organization for Research and Treatment of Cancer (EORTC), patients with T4, N2-N3 nodal stage as well as M1 metastatic status are precluded from surgery [3] The role of PET/CT in oncology is well established It has changed the diagnostic algorithm in cancer patients [4–6] In mesothe- Peer review under responsibility of The Egyptian Society of Radiology and Nuclear Medicine ⇑ Corresponding author E-mail address: mohamedhouseni@gmail.com (M Houseni) lioma, PET/CT is a powerful modality in the depiction of mediastinal as well as chest wall invasion [7] It is also superior to other modalities in the detection of lymphadenopathy and metastatic disease [8] On the other hand, exact local tumor extension and the assessment of small lesions are challenging with PET/CT [9] Contrast CT chest is widely used to evaluate pleural mesothelioma It defines primary tumor outline, local invasion, intrathoracic lymphadenopathy and extra-thoracic extension [8] This is because of the superb soft tissue resolution and the availability of multi-planar image reconstruction from the volumetric acquisition [10] However, CT is limited when assessing normal sized lymph nodes In addition, CT suffers from reduced sensitivity in the detection of metastatic lesions that are not associated with structural changes [11] It is still recommended to perform attenuation correction for PET using low dose non-contrast CT to avoid beam-hardening artifacts from contrast Furthermore, metabolic activity may falsely increased as a result of contrast [12] An added issue in the thorax http://dx.doi.org/10.1016/j.ejrnm.2016.12.011 0378-603X/Ó 2016 The Egyptian Society of Radiology and Nuclear Medicine Production and hosting by Elsevier This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Please cite this article in press as: Houseni M et al Value of contrast CT in combination with PET/CT in mesothelioma staging: Optimal protocol for initial assessment Egypt J Radiol Nucl Med (2016), http://dx.doi.org/10.1016/j.ejrnm.2016.12.011 M Houseni et al / The Egyptian Journal of Radiology and Nuclear Medicine xxx (2016) xxx–xxx is respiratory motion artifact, which affects the spatial resolution of PET images and the accuracy of the attenuation correction information [13] Therefore, the acquisition of PET and low dose CT in quite respiration will limit this artifact; then performing contrast CT with breath-hold will provide superior chest images The purpose of this study was to assess the value of contrast enhanced CT (ceCT) when added to positron emission tomography combined with the standard low-dose non-contrast CT (PET/CT) protocols for staging patients with malignant pleural mesothelioma (MPM) collimation for detector configuration The gantry rotation time was 0.5 s, field of view of 50 cm and reconstruction matrix of 512 512 Automated exposure control was applied for all patients (CARE Right, Siemens Medical Solutions, Forchheim, Germany) with 120 kV tube potential and the average mAs of 150 Trans-axial images were reconstructed at 1.5 mm slice thickness in mm increment using a convolution kernel B20f body filter For multi-planar evaluation, coronal and sagittal images with a 1.5 mm slice thickness in mm increment were reconstructed 2.3 Image interpretation Methods 2.1 Patients This retrospective study included adult patients referred for initial assessment of pathologically proven pleural mesothelioma This study was approved by the institutional review board The need for informed consent was waved Forty-seven consecutive patients were included during the period between November 2012 and February 2016 All patients have performed 18F-FDG-PET/CT with low dose CT followed by diagnostic contrast enhanced CT as part of the imaging protocol 2.2 Imaging protocol All patients underwent 18F-FDG PET/CT examinations using a dedicated PET/CT scanner equipped with a 20-slice CT system (Siemens mCT20, Biograph Classic; Siemens Medical Solutions, Knoxville, USA) Patients fasted for about h before the injection time Serum glucose levels were measured before injection to confirm euglycemia (blood glucose level