Non‐contrast estimate of blood–brain barrier permeability in humans using arterial spin labeling and magnetization transfer at 7 T

• Published in: NMR in biomedicine Vol. 36; no. 7; pp. e4908 - n/a
• Main Authors: Mahmud, Sultan Z., Denney, Thomas S., Bashir, Adil
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.07.2023
• Subjects: arterial spin labeling; Biological products; Blood-brain barrier; Caffeine; Central nervous system; Central nervous system diseases; Labeling; Macromolecules; Magnetization; magnetization transfer; Membrane permeability; Parameter sensitivity; Perfusion; Permeability; Sensitivity analysis; Spin labeling; Substantia alba; Substantia grisea; Tissues; water extraction fraction; blood-brain barrier; magnetization transfer; perfusion; water extraction fraction; arterial spin labeling; permeability
• ISSN: 0952-3480; 1099-1492
• DOI: 10.1002/nbm.4908

Blood–brain barrier (BBB) dysfunction is associated with a number of central nervous system diseases. This study demonstrates the application of a novel noninvasive technique to measure the BBB permeability in the human brain at 7 T. The technique exploits the fact that, when tissue macromolecules are saturated by off‐resonance RF pulse, the intravascular and the extravascular (tissue) water experience different magnetization transfer effects. This principle was combined with arterial spin labeling to distinguish between the intravascular and the tissue water, and was used to calculate perfusion, water extraction fraction (E), and BBB permeability surface area product for water (PS). Simultaneous coregistered magnetization transfer ratio maps were also generated that can provide valuable additional information. Eighteen healthy volunteers (seven females), age = 27 ± 11 years and weight = 65 ± 9 kg, participated in the study. Average perfusion was 67 ± 5 and 29 ± 4 ml/100 g/min (p < 0.05); and E was 0.921 ± 0.025 and 0.962 ± 0.015 (p < 0.05) in the gray matter (GM) and the white matter (WM), respectively. PS was higher in the GM (171 ± 20 ml/100 g/min) compared with the WM (95 ± 18 ml/100 g/min) (p < 0.05). The parameters exhibited good reliability with test re‐test experiments. The sensitivity of this technique was demonstrated by 200 mg caffeine intake, which resulted in a decrease in the resting PS by ~31%. A new completely noninvasive technique to measure the blood–brain barrier (BBB) using arterial spin labeling and magnetization transfer was demonstrated. In addition to perfusion and BBB permeability, this technique can also provide a magnetization transfer ratio (MTR) map; and this combined information can be very useful in assessing central nervous system diseases.