European Journal of Radiology 84 (2015) 1424–1431

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Respiratory gated PET/CT of the liver: A novel method and its impact on the detection of colorectal liver metastases Anselm Schulz a,e,∗ , Johannes Clemens Godt a,e , Johann Baptist Dormagen a , Jon Erik Holtedahl c , Trond Velde Bogsrud a,d , Knut Jørgen Labori b , Nils-Einar Kløw a,e , Tore Bach-Gansmo a a

Department of Radiology and Nuclear Medicine, Oslo University Hospital, Postboks Pb 4956 Nydalen, 0424 Oslo, Norway Department of Hepato-Pancreato-Biliary Surgery, Oslo University Hospital, Postboks 4950 Nydalen, 0424 Oslo, Norway c The Intervention Centre, Oslo University Hospital, Postboks 4950 Nydalen, 0424 Oslo, Norway d Department of Nuclear Medicine and PET-Center, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark e Institute of Clinical Medicine, University of Oslo, P.O. Box 1171 Blindern, 0318 Oslo, Norway b

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Article history: Received 28 April 2015 Accepted 5 May 2015 Keywords: PET/CT Respiratory gated PET/CT Liver Metastases Diagnostic performance

a b s t r a c t Purpose: To evaluate the diagnostic performance of a new method for respiratory gated positron emission tomography (rgPET/CT) for colorectal liver metastases (CRLM), secondly, to assess its additional value to standard PET/CT (PET/CT). Materials and methods: Forty-three patients scheduled for resection of suspected CRLM were prospectively included from September 2011 to January 2013. None of the patients had previously undergone treatment for their CRLM. All patients underwent PET/CT and rgPET/CT in the same session. For rgPET/CT an in-house developed electronic circuit was used which displayed a color-coded countdown for the patient. The patients held their breath according to the countdown and only the data from the inspiration breath-hold period was used for image reconstruction. Two independent and blinded readers evaluated both PET/CT and rgPET/CT separately. The reference standard was histopathological confirmation for 73 out of 131 CRLM and follow-up otherwise. Results: Reference standard identified 131 CRLM in 39/43 patients. Nine patients accounted for 25 mucinous CRLM. The overall per-lesion sensitivity for detection of CRLM was for PET/CT 60.0%, for rgPET/CT 63.1%, and for standard + rgPET/CT 67.7%, respectively. Standard + rgPET/CT was overall significantly more sensitive for CRLM compared to PET/CT (p = 0.002) and rgPET/CT (p = 0.031). The overall positive predictive value (PPV) for detection of CRLM was for PET/CT 97.5%, for rgPET/CT 95.3%, and for standard + rgPET/CT 93.6%, respectively. Conclusion: Combination of PET/CT and rgPET/CT improved the sensitivity significantly for CRLM. However, high patient compliance is mandatory to achieve optimal performance and further improvements are needed to overcome these limitations. The diagnostic performance of the evaluated new method for rgPET/CT was comparable to earlier reported technically more complex and expensive methods. © 2015 Elsevier Ireland Ltd. All rights reserved.

1. Introduction Liver metastases are a main concern in patients with colorectal cancer. According to a recent large meta-analysis, magnetic

∗ Corresponding author at: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Ullevål sykehus, Postboks Pb 4956 Nydalen, 0424 Oslo, Norway. Tel.: +47 22 11 93 50; fax: +47 22 11 78 62. E-mail addresses: [email protected] (A. Schulz), [email protected] (J.C. Godt), [email protected] (J.B. Dormagen), [email protected] (J.E. Holtedahl), [email protected] (T.V. Bogsrud), [email protected] (K.J. Labori), [email protected] (N.-E. Kløw), [email protected] (T. Bach-Gansmo). http://dx.doi.org/10.1016/j.ejrad.2015.05.011 0720-048X/© 2015 Elsevier Ireland Ltd. All rights reserved.

resonance imaging (MRI) has the best diagnostic performance for colorectal liver metastases (CRLM) [1]. In the same study computed tomography (CT) and 2-deoxy-2-[18F]-fluoro-d-glucose (FDG) positron emission tomography (PET) had comparable sensitivities and FDG PET was suggested as second-line modality, however limited data was available about FDG PET co-registered with CT (PET/CT). National Comprehensive Cancer Network (NCCN)guidelines suggest CT or MRI for the detection of CRLM [2]. In the further workup of metastatic colorectal cancer PET/CT may be used to rule out extrahepatic metastases in patients otherwise eligible for liver resection. Also, PET/CT may contribute with additional information in cases where MRI is indeterminate for the characterization of liver lesions.

A. Schulz et al. / European Journal of Radiology 84 (2015) 1424–1431

The main reasons for the lower intrahepatic diagnostic performance of PET/CT compared to MRI are the lower spatial resolution, the relatively high normal liver FDG-uptake and reduced conspicuity of focal FDG-uptake due to respiratory motion of the thorax and upper abdomen. Low spatial resolution results in underestimation of uptake and failure to discriminate abnormal FDG-uptake from uptake in normal liver, which is particularly problematic in small metastatic lesions (

CT of the liver: A novel method and its impact on the detection of colorectal liver metastases.

To evaluate the diagnostic performance of a new method for respiratory gated positron emission tomography (rgPET/CT) for colorectal liver metastases (...
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