Courtesy of Dr Michael Thrippleton, this image shows brain MRI from a patient with cerebral small vessel disease (cSVD), mapping the permeability–surface area product (PS) as measured with dynamic contrast-enhanced (DCE) MRI in A and B with a corresponding T2w-FLAIR image presented in C. Higher PS values represent higher leakage rates of contrast agent molecules from the capillary blood plasma space to extravascular extracellular space. Changes of the cerebrovascular system leading to blood-brain barrier (BBB) leakage play a pivotal role in the early development of cSVD. However, as this increase in BBB permeability is generally subtle it is difficult to detect in images from standard clinical MRI protocols, such as T2w-FLAIR. The DCE-MRI technique allows for quantification of subtle BBB dysfunction, showing promise for application in clinical research studies.
The PS map in A above illustrates that the noise and artifact levels for individual voxels can be substantial, and thus spatially smoothing the raw DCE-MRI images during preprocessing aids visual inspection, as can be seen in the PS map in B above. In both maps, the low level of leakage is apparent, with noticeably higher values in the lesion from an acute lacunar stroke 6 weeks prior to the scan (indicated by the cross hairs) but also in the normal-appearing periventricular white matter (cf. C above) ipsilateral to the stroke lesion.
The image is taken from a recent review with consensus recommendations from the HARNESS (HARmoNising Brain Imaging MEthodS for VaScular Contributions to Neurodegeneration) Initiative published in Alzheimer’s & Dementia:
Thrippleton MJ, Backes WH, Sourbron S, Ingrisch M, van Osch MJP, Dichgans M, Fazekas F, Ropele S, Frayne R, van Oostenbrugge RJ, Smith EE, Wardlaw JM. Quantifying blood-brain barrier leakage in small vessel disease: Review and consensus recommendations. Alzheimers Dement 2019; 15(6):840-858.