Pet/Mri

Lee, Jae Sung; Kang, Keon Wook

doi:10.1007/978-1-4419-0802-5_33

Cited by 2 publications

(2 citation statements)

References 45 publications

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“…MRI has several advantages over CT, including better soft-tissue contrast, no additional radiation hazard, and true 4-dimensional simultaneous imaging (9)(10)(11). It is likely that combined PET/MRI and SPECT/MRI systems will facilitate the wider use of radiotracer technologies for clinical and investigational purposes.…”

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confidence: 99%

Comparison of Segmentation-Based Attenuation Correction Methods for PET/MRI: Evaluation of Bone and Liver Standardized Uptake Value with Oncologic PET/CT Data

et al. 2012

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For attenuation correction (AC) in PET/MRI systems, segmentation-based methods are most often used. However, the standardized uptake value (SUV) of lesions in the bone and liver, which have higher attenuation coefficients than other organs, can be underestimated, potentially leading to misinterpretation of clinical cases. Errors in SUV estimation are also dependent on the segmentation schemes used in the segmentation-based AC. In this study, this potential bias in SUV estimation using 4 different segmentation-based AC methods was evaluated for the PET/CT data of cancer patients with bone and liver lesions. Methods: Forty patients who had spine or liver lesions and underwent 18 F-FDG PET/CT participated (18 women and 22 men; 20 spine lesions and 20 liver lesions; mean age (6SD), 60.5 6 11.4 y; mean body weight, 57.7 6 10.4 kg). The patient body region was extracted from the CT image and categorized into 5 tissue groups (air, lungs, fat, water, and bone) using Hounsfield unit thresholds, which were determined from the CT histogram. Four segmentation-based AC methods (SLA [soft-tissue/lung/ air], WFLA [water/fat/lung/air], SLAB [soft-tissue/lung/air/bone], and WFLAB [water/fat/lung/air/bone]) were compared with CTbased AC. The mean attenuation coefficient for each group was calculated from 40 CT images and assigned to the attenuation maps. PET sinograms were reconstructed using segmentationand CT-based AC maps, and mean SUV in the lesions was compared. Results: Mean attenuation coefficients for air, lungs, fat, water, and bone were 0.0058, 0.0349, 0.0895, 0.0987, and 0.1178 cm 21 , respectively. In the spine lesions, the SUVs were underestimated by 16.4% 6 8.5% (SLA AC) and 14.7% 6 7.5% (WFLA AC) but not to a statistically significant extent for SLAB and WFLAB AC relative to CT AC. In the liver lesions, the SUVs were underestimated by 11.1% 6 2.6%, 8.1% 6 3.0%, 6.8% 6 3.8%, and 4.1% 6 3.8% with SLA, SLAB, WFLA, and WFLAB AC, respectively. Conclusion: Without bone segmentation, the SUVs of spine lesions were considerably underestimated; however, the bias was acceptable with bone segmentation. In liver lesions, the segmentation-based AC methods yielded a negative bias in SUV; however, inclusion of the bone and fat segments reduced the SUV bias. The results of this study will be useful for understanding organ-dependent bias in SUV between PET/CT and PET/MRI. Hybri d imaging devices such as PET/CT and SPECT/CT are now widely used in clinical and preclinical studies. Morphologic information provided by CT is particularly useful for the localization of abnormal uptake of radiotracers and for g-ray attenuation correction (AC) (1-3). Inaccurate AC of PET and SPECT images can lead to incorrect quantification and misinterpretation of lesions (4-9).MRI is another important morphologic imaging tool that can be combined with PET or SPECT. MRI has several advantages over CT, including better soft-tissue contrast, no additional radiation hazard, and true 4-dimensional simultaneous imaging (9-11). It is likely that combined PET/MR...

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Comparison of Segmentation-Based Attenuation Correction Methods for PET/MRI: Evaluation of Bone and Liver Standardized Uptake Value with Oncologic PET/CT Data

et al. 2012

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“…A whole-body simultaneous positron emission tomography (PET)-MR imager is fast becoming a reality as major works carried out with small animal systems have proven to be very successful (Judenhofer et al 2008, Catana et al 2006, Lee and Hong 2010, Lee and Kang 2012. Most PET/magnetic resonance imaging (MRI) systems for small animal imaging use radio frequency (RF)-transceiver coils for RF transmission and reception.…”

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confidence: 99%

SiPM-PET with a short optical fiber bundle for simultaneous PET-MR imaging

Hong

Kang

et al. 2012

Phys. Med. Biol.

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For positron emission tomography (PET) inserts to magnetic resonance imaging (MRI) applications, optical fibers have been used for some time to transfer scintillation photons to photomultiplier tubes positioned outside the fringe magnetic field. We previously proposed a novel utilization of an optical fiber for good radio frequency (RF) transmission from body coils to an imaging object. Optical fiber bundles between silicon photomultipliers (SiPM) and scintillation crystals provide an increased spacing between RF-shielded electronics boxes, facilitating RF passage from the body RF coils to imaging objects. In this paper, we present test results of a SiPM-PET system with a short optical fiber bundle for simultaneous PET-MR imaging. We built the SiPM-PET system which consisted of 12 SiPM-PET modules; each module was assembled with a lutetium yttrium oxyorthosilicatecrystal block, a 31 mm optical fiber bundle, a Hamamatsu multi-pixel photon counter S11064-050P and a signal processing box shielded with copper. The SiPM-PET system, with a face-to-face distance of 71 mm, was placed inside a 3 T MRI. A small surface coil placed inside the SiPM-PET system was used to receive the signal from phantoms while the body RF coil transmitted the RF pulses. The SiPM-PET system showed little performance degradation during the simultaneous PET-MR imaging and it caused no significant degradation of MR images with turbo spin echo (TSE), gradient echo or 3D spoiled gradient recalled sequences. Echo planar imaging MR images with and without the SiPM-PET inside the MR scanner were significantly worse than the images obtained with the TSE sequence.

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Pet/Mri

Cited by 2 publications

References 45 publications

Comparison of Segmentation-Based Attenuation Correction Methods for PET/MRI: Evaluation of Bone and Liver Standardized Uptake Value with Oncologic PET/CT Data

Comparison of Segmentation-Based Attenuation Correction Methods for PET/MRI: Evaluation of Bone and Liver Standardized Uptake Value with Oncologic PET/CT Data

SiPM-PET with a short optical fiber bundle for simultaneous PET-MR imaging

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