Early Experience of Translating pH-Weighted MRI to Image Human Subjects at 3 Tesla

• Published in: Stroke (1970) Vol. 41; no. 10_suppl_1; pp. S147 - S151
• Main Authors: Sun, Phillip Zhe, Benner, Thomas, Copen, William A., Sorensen, A. Gregory
• Format: Journal Article
• Language: English
• Published: United States 01.10.2010
• Subjects: Acidosis - pathology; Adult; Animals; Brain - pathology; Brain Ischemia - pathology; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging - methods; Male; Rats; Rats, Wistar; Stroke - pathology
• ISSN: 0039-2499; 1524-4628; 1524-4628
• DOI: 10.1161/STROKEAHA.110.595777

Background and Purpose— In acute stroke, mismatch between lesions seen on diffusion- (DWI) and perfusion-weighted (PWI) MRI has been used to identify ischemic tissue before irreversible damage. Nevertheless, the concept of PWI/DWI mismatch is oversimplified and the ischemic tissue metabolic status and outcome are often heterogeneous. Tissue pH, a well-regulated physiological index that alters on disrupted tissue metabolism, may provide a surrogate metabolic imaging marker that augments the DWI and PWI for penumbra imaging. Methods— pH-weighted MRI was obtained by probing the pH-dependent amide proton transfer between endogenous mobile proteins/peptides and tissue water. The technique was validated using animal stroke models, optimized for human use, and preliminarily tested for imaging healthy volunteers. Results— pH-weighted MRI is sensitive and specific to ischemic tissue acidosis. pH MRI can be optimized for clinical use, and a pilot human study showed it is feasible using a standard 3 Tesla MRI scanner. Conclusions— Ischemic acidosis can be imaged via an endogenous pH-weighted MRI technique, which complements conventional PWI and DWI for penumbra imaging. pH-weighted MRI has been optimized and appears feasible and practical in imaging human subjects. Additional study is necessary to elucidate the diagnostic use of pH MRI in stroke patients.