Impact of improved attenuation correction on 18F-FDG PET/MR hybrid imaging of the heart

Abstract

PurposeThe aim of this study was to evaluate and quantify the effect of improved attenuation correction (AC) including bone segmentation and truncation correction on 18F-Fluordesoxyglucose cardiac positron emission tomography/magnetic resonance (PET/MR) imaging.MethodsPET data of 32 cardiac PET/MR datasets were reconstructed with three different AC-maps (1. Dixon-VIBE only, 2. HUGE truncation correction and bone segmentation, 3. MLAA). The Dixon-VIBE AC-maps served as reference of reconstructed PET data. 17-segment short-axis polar plots of the left ventricle were analyzed regarding the impact of each of the three AC methods on PET quantification in cardiac PET/MR imaging. Non-AC PET images were segmented to specify the amount of truncation in the Dixon-VIBE AC-map serving as a reference. All AC-maps were evaluated for artifacts.ResultsUsing HUGE + bone AC results in a homogeneous gain of ca. 6% and for MLAA 8% of PET signal distribution across the myocardium of the left ventricle over all patients compared to Dixon-VIBE AC only. Maximal relative differences up to 18% were observed in segment 17 (apex). The body volume truncation of -12.7 ± 7.1% compared to the segmented non-AC PET images using the Dixon-VIBE AC method was reduced to -1.9 ± 3.9% using HUGE and 7.8 ± 8.3% using MLAA. In each patient, a systematic overestimation in AC-map volume was observed when applying MLAA. Quantitative impact of artifacts showed regional differences up to 6% within single segments of the myocardium.ConclusionsImproved AC including bone segmentation and truncation correction in cardiac PET/MR imaging is important to ensure best possible diagnostic quality and PET quantification. The results exhibited an overestimation of AC-map volume using MLAA, while HUGE resulted in a more realistic body contouring. Incorporation of bone segmentation into the Dixon-VIBE AC-map resulted in homogeneous gain in PET signal distribution across the myocardium. The majority of observed AC-map artifacts did not significantly affect the quantitative assessment of the myocardium.

Evaluation of improved attenuation correction in whole-body PET/MR on patients with bone metastasis using various radiotracers

“…In recent clinical studies on whole-body PET/MR investigating oncologic patients injected with 18 F-FDG as radiotracer, it was shown that improved AC including a bone model and methods for truncation correction showed robust results and MR-based truncation correction provided realistic body contours [11,12,20]. In contrast to these previous studies, the improved AC method in the present study was applied to a patient collective with bone lesions and that was injected with four different radiotracers ( 18 F-FDG, 68 Ga-DOTATOC, 68 Ga-PSMA, and 124 I-MIBG).…”

Procedural recommendations of cardiac PET/CT imaging: standardization in inflammatory-, infective-, infiltrative-, and innervation (4Is)-related cardiovascular diseases: a joint collaboration of the EACVI and the EANM

“…For the PET acquisition and reconstruction in PET/MR, recommendations (95). In general, the use of attenuation correction methods incorporating bone should be encouraged when they become available (96). When available, the use of free-breathing radial VIBE sequences for AC is encouraged since these AC sequences appear to reduce breathing and motion artifacts (97).…”

“…Currently commercially available Dixon-based MR-based attenuation correction methods using four tissue class segmentation are preferred for [ 18 F]FDG quantification ( 94 ) and have been shown to yield quantitatively comparable results as PET/CT for perfusion imaging with [ 15 O]water ( 95 ). In general, the use of attenuation correction methods incorporating bone should be encouraged when they become available ( 96 ). When available, the use of free-breathing radial VIBE sequences for AC is encouraged since these AC sequences appear to reduce breathing and motion artifacts ( 97 ).…”

PET/MRI attenuation estimation in the lung: A review of past, present, and potential techniques

“…Additional variability can arise from different PET reconstruction parameters, registration algorithms, FOV truncation compensation, MR‐coils, SUV error types (mean vs maximum or whole‐lung vs a voxel basis), and patient diseases. A better consensus and more lung‐specifically targeted studies would be of great benefit for future applications of lung PET/MRI.…”