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Absolute choline tissue concentration mapping for prostate cancer localization and characterization using 3D 1 H MRSI without water‐signal suppression
Author(s) -
Tayari Nassim,
Wright Alan J.,
Heerschap Arend
Publication year - 2022
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.29012
Subject(s) - choline , prostate cancer , magnetic resonance spectroscopic imaging , metabolite , prostate , creatine , signal (programming language) , chemistry , nuclear magnetic resonance , cancer , nuclear medicine , magnetic resonance imaging , medicine , radiology , biochemistry , computer science , physics , programming language
Purpose Until now, 1 H MRSI of the prostate has been performed with suppression of the large water signal to avoid distortions of metabolite signals. However, this signal can be used for absolute quantification and spectral corrections. We investigated the feasibility of water‐unsuppressed MRSI in patients with prostate cancer for water signal–mediated spectral quality improvement and determination of absolute tissue levels of choline. Methods Eight prostate cancer patients scheduled for radical prostatectomy underwent multi‐parametric MRI at 3 T, including 3D water‐unsuppressed semi‐LASER MRSI. A postprocessing algorithm was developed to remove the water signal and its artifacts and use the extracted water signal as intravoxel reference for phase and frequency correction of metabolite signals and for absolute metabolite quantification. Results Water‐unsuppressed MRSI with dedicated postprocessing produced water signal and artifact‐free MR spectra throughout the prostate. In all patients, the absolute choline tissue concentration was significantly higher in tumorous than in benign tissue areas (mean ± SD: 7.2 ± 1.4 vs 3.8 ± 0.7 mM), facilitating tumor localization by choline mapping. Tumor tissue levels of choline correlated better with the commonly used (choline + spermine + creatine)/citrate ratio ( r = 0.78 ± 0.1) than that of citrate ( r = 0.21 ± 0.06). The highest maximum choline concentrations occurred in high‐risk cancer foci. Conclusion This report presents the first successful water‐unsuppressed MRSI of the whole prostate. The water signal enabled amelioration of spectral quality and absolute metabolite quantification. In this way, choline tissue levels were identified as tumor biomarker. Choline mapping may serve as a tool in prostate cancer localization and risk scoring in multi‐parametric MRI for diagnosis and biopsy procedures.