Elsevier

European Journal of Radiology

Volume 84, Issue 11, November 2015, Pages 2097-2102
European Journal of Radiology

Implementation of FAST-PET/MRI for whole-body staging of female patients with recurrent pelvic malignancies: A comparison to PET/CT

https://doi.org/10.1016/j.ejrad.2015.08.010Get rights and content

Highlights

  • FAST-PET/MRI provides equivalent diagnostic performance for whole-body restaging as PET/CT.

  • FAST-PET/MRI offers markedly reduced radiation exposure compared to full-dose PET/CT.

  • FAST-PET/MRI is a high-quality alternative for evaluation of gynecological cancer patients.

Abstract

Objectives

To compare the diagnostic competence of FAST-PET/MRI and PET/CT for whole-body staging of female patients suspect for a recurrence of a pelvic malignancy.

Methods

24 female patients with a suspected tumor recurrence underwent a PET/CT and subsequent PET/MRI examination. For PET/MRI readings a whole-body FAST-protocol was implemented. Two readers separately evaluated the PET/CT and FAST PET/MRI datasets regarding identification of all tumor lesions and qualitative assessment of visual lesion-to-background contrast (4-point ordinal scale).

Results

Tumor relapse was present in 21 of the 24 patients. Both, PET/CT and PET/MRI allowed for correct identification of tumor recurrence in 20 of 21 cases. Lesion-based sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy for the detection of malignant lesions were 82%, 91%, 97%, 58% and 84% for PET/CT and 85%, 87%, 96%, 63% and 86% for PET/MRI, lacking significant differences. Furthermore, no significant difference for lesion-to-background contrast of malignant and benign lesions was found.

Conclusion

FAST-PET/MRI provides a comparably high diagnostic performance for restaging gynecological cancer patients compared to PET/CT with slightly prolonged scan duration, yet enabling a markedly reduced radiation exposure.

Introduction

Within the last 15 years, hybrid imaging, in terms of positron emission tomography/computed tomography (PET/CT) imaging, has been successfully introduced into oncologic imaging for (re) staging of numerous tumor entities, combining the assessment of valuable metabolic and anatomical information for the identification of cancer lesions [1], [2], [3]. While the hybrid nature of PET/CT has been shown beneficial compared to other cross-sectional imaging techniques for the detection of metastatic sites [4], [5], it also causes one of its major disadvantages, by means of an increased radiation dose due to the combination of PET and whole-body full-dose CT [6], [7].

The implementation of integrated positron emission tomography/magnetic resonance imaging (PET/MRI) scanners enables high-quality assessment of cancer patients by combining the diagnostic advantages of simultaneous whole-body PET and whole-body MR imaging [8], [9]. MRI, as part of this new emerging imaging technique, provides high-resolution anatomical information with excellent soft tissue contrast under the avoidance of potentially harmful ionizing radiation exposure. Current publications demonstrate the comparable diagnostic performance of integrated PET/MRI and PET/CT for staging and restaging of numerous tumor entities, including gynecological cancers [10], [11], [12]. However, up to current status, one major disadvantage of PET/MRI studies lies in a markedly prolonged examination time, mainly caused by the acquisition of a substantial number of MR sequences. Hence, with regard to patient comfort, well-considered and suitable MR imaging protocols are required.

Thus, the aim of this trial was to evaluate the diagnostic ability of a FAST-protocol for whole-body PET/MR imaging, including high-resolution morphological (T1w- and T2w sequences), functional (diffusion-weighted imaging, DWI) as well as metabolic (PET) assessment for restaging female patients with pelvic malignancies in comparison to PET/CT.

Section snippets

Patients

The present study was approved by the institutional review board. 39 female patients suspect for a recurrence of a pelvic malignancy were enrolled in this retrospective trial. All patients underwent a clinically indicated whole-body PET/CT and subsequently an additional whole-body PET/MRI examination after informed and written consent was obtained. Suspicion for a tumor recurrence was determined based on clinical follow-up as well as abnormal findings in cross-sectional imaging follow-up (CT,

Patient based analysis

PET/CT and subsequent PET/MRI examinations were completed successfully in all 24 patients. Table 2 gives an overview of the mean scan duration of a whole-body PET/CT, a standard whole-body PETMRI examination as well as of the FAST-PET/MRI protocol, applied for restaging patients suspect for a recurrent pelvic malignancy.

The estimated mean effective dose of a full-dose whole-body PET/CT examination amounted to 20.7 ± 4.1 mSv, with the CT-component amounting to 16.0 ± 4.0 mSv (77.3%) and the

Discussion

Our study results demonstrate the feasibility and high diagnostic value of the applied FAST-PET/MRI protocol for restaging female patients suspect for a recurrent pelvic malignancy. On a lesion-based analysis, FAST-PET/MRI and PET/CT yielded an equivalently high diagnostic performance for the detection and visualization of tumor recurrences. Furthermore, the implementation of a FAST-PET/MRI protocol enables high-quality restaging of gynecological cancer patients within only slightly longer scan

Conflict of interest

All authors declare that they have no conflict of interest.

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