A multi-centre evaluation of eleven clinically feasible brain PET/MRI attenuation correction techniques using a large cohort of patients

Abstract

All of the proposed novel methods have an average global performance within likely acceptable limits (±5% of CT-based reference), and the main difference among the methods was found in the robustness, outlier analysis, and clinical feasibility. Overall, the best performing methods were MR-ACBOSTON, MR-ACMAXPROB, MR-ACRESOLUTE and MR-ACUCL, ordered alphabetically. These methods all minimized the number of outliers, standard deviation, and average global and local error. The methods MR-ACMUNICH and MR-ACCAR-RiDR were both within acceptable quantitative limits, so these methods should be considered if processing time is a factor. The method MR-ACSEGBONE also demonstrates promising results, and performs well within the likely acceptable quantitative limits. For clinical routine scans where processing time can be a key factor, this vendor-provided solution currently outperforms most methods. With the performance of the methods presented here, it may be concluded that the challenge of improving the accuracy of MR-AC in adult brains with normal anatomy has been solved to a quantitatively acceptable degree, which is smaller than the quantification reproducibility in PET imaging.

Hybrid Imaging: Instrumentation and Data Processing

“…In general, these approaches perform reasonably well, although for specific application their accuracy may not be sufficient [222]. Thus, several advanced AC methods have been explored in conjunction with various types of PET/MR examinations [217,223,224]. Most of the developed AC methods are tailored to brain examinations and provide acceptable accuracies (with deviations below 5% respect to CT-based AC) [217].…”

“…Thus, several advanced AC methods have been explored in conjunction with various types of PET/MR examinations [217,223,224]. Most of the developed AC methods are tailored to brain examinations and provide acceptable accuracies (with deviations below 5% respect to CT-based AC) [217]. A selection of available MRI based AC methods for the head is given in Figure 6.…”

“…A selection of available MRI based AC methods for the head is given in Figure 6. A detailed comparison of these methods can be found in Ladefoged et al [217]. However, for AC of body parts other than the brain as well as for AC of non-rigid hardware components (e.g., flexible surface coils), challenges still persist [225,226], such as body truncation, metal and respiratory artifacts, MR coils attenuation, etc.…”

MR-Based Attenuation Correction in Brain PET/MR Studies: A Short Review

“…These methods are based on iterative algorithms, and therefore are also referred to as reconstruction-based [29]. The most frequently used reconstruction function is the Maximum Likelihood reconstruction of Attenuation and Activity (MLAA).…”

PET/MR Imaging

“…While this seems to be the best approach so far for the brain, it is not clear how effective it will be for those with anatomy that is not well represented in the database, and its extension to body remains a challenge. Developing improved methods for MRAC remains an active research area [15].…”