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EJNMMI Phys. 2015 Dec;2(1):21. doi: 10.1186/s40658-015-0125-0. Epub 2015 Sep 18.

Correcting for respiratory motion in liver PET/MRI: preliminary evaluation of the utility of bellows and navigated hepatobiliary phase imaging.

Author information

1
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA. thomas.hope@ucsf.edu.
2
Department of Radiology, San Francisco VA Medical Center, San Francisco, CA, USA. thomas.hope@ucsf.edu.
3
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA.
4
Division of Hematology/Oncology, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA.
5
Department of Radiology, San Francisco General Hospital, San Francisco, CA, USA.
6
Division of Surgical Oncology, Department of Surgery, University of California, San Francisco, San Francisco, CA, USA.

Abstract

BACKGROUND:

The purpose of this study was to evaluate the utility of bellows-based respiratory compensation and navigated hepatobiliary phase imaging to correct for respiratory motion in the setting of dedicated liver PET/MRI.

METHODS:

Institutional review board approval and informed consent were obtained. Six patients with metastatic neuroendocrine tumor were imaged using Ga-68 DOTA-TOC PET/MRI. Whole body imaging and a dedicated 15-min liver PET acquisition was performed, in addition to navigated and breath-held hepatobiliary phase (HBP) MRI. Liver PET data was reconstructed three ways: the entire data set (liver PET), gated using respiratory bellows (RC-liver PET), and a non-gated data set reconstructed using the same amount of data used in the RC-liver PET (shortened liver PET). Liver lesions were evaluated using SUVmax, SUVpeak, SUVmean, and Volisocontour. Additionally, the displacement of each lesion between the RC-liver PET images and the navigated and breath-held HBP images was calculated.

RESULTS:

Respiratory compensation resulted in a 43 % increase in SUVs compared to ungated data (liver vs RC-liver PET SUVmax 26.0 vs 37.3, p < 0.001) and a 25 % increase compared to a non-gated reconstruction using the same amount of data (RC-liver vs shortened liver PET SUVmax 26.0 vs 32.6, p < 0.001). Lesion displacement was minimized using navigated HBP MRI (1.3 ± 1.0 mm) compared to breath-held HBP MRI (23.3 ± 1.0 mm).

CONCLUSIONS:

Respiratory bellows can provide accurate respiratory compensation when imaging liver lesions using PET/MRI, and results in increased SUVs due to a combination of increased image noise and reduced respiratory blurring. Additionally, navigated HBP MRI accurately aligns with respiratory compensated PET data.

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