Evaluation of Sinus/Edge-Corrected Zero-Echo-Time-Based Attenuation Correction in Brain PET/MRI

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Radiology

Background:

• Zero-echo-time (ZTE) based attenuation correction (ZTAC) in brain PET/MRI faces challenges with accurate air/tissue/bone boundary classification.
• Misclassification in ZTAC can lead to significant errors in positron emission tomography (PET) quantification.
• Existing methods like uncorrected ZTAC (ZTAC_UC) and CT atlas-based attenuation correction (ATAC) have limitations in accuracy.

Purpose of the Study:

• To evaluate the performance of a novel sinus/edge-corrected ZTAC (ZTAC_SEC) method.
• To compare ZTAC_SEC accuracy against uncorrected ZTAC (ZTAC_UC) and CT atlas-based attenuation correction (ATAC).
• To assess the impact of ZTAC_SEC on PET quantification accuracy in brain PET/MRI.

Main Methods:

• Whole-body 18F-FDG PET/MRI scans from 12 patients were analyzed.
• ZTAC_UC, ZTAC_SEC, and ATAC were applied for PET attenuation correction, with CT-based attenuation correction (CTAC) as reference.
• Quantitative evaluation involved measuring PET mean uptake values in predefined volumes of interest and comparing methods using paired t-tests and error histograms.

Main Results:

• ZTAC_SEC achieved overall PET quantification accuracy (0.2% ± 2.4%) comparable to CTAC.
• ZTAC_SEC significantly outperformed ZTAC_UC (5.6% ± 3.5%) and ATAC (-0.9% ± 5.0%) in accuracy.
• Substantial improvements were observed with ZTAC_SEC in the cerebellum (0.6% ± 2.7%) compared to ZTAC_UC (8.1% ± 3.5%) and ATAC (-4.1% ± 4.3%).
• Error histograms confirmed that ZTAC_SEC substantially reduced the magnitude and variation of voxel-based uptake errors.

Conclusions:

• Sinus/edge-corrected ZTAC (ZTAC_SEC) provides accurate PET quantification in brain PET/MRI.
• ZTAC_SEC demonstrates accuracy comparable to CT-based attenuation correction (CTAC).
• ZTAC_SEC shows particular efficacy in improving PET quantification accuracy in the cerebellum.