Functional imaging with MR T1 contrast: a feasibility study with blood-pool contrast agent

Abstract

The aim of this study was to prove the concept of using a long intravenous half-life blood-pool T1 contrast agent as a new functional imaging method. For each of ten healthy subjects, two dynamic magnetic resonance (MR) protocols were carried out: (1) a reference run with a typical T2* echo-planar imaging (EPI) sequence based on the blood oxygenation level-dependent (BOLD) effect and (2) a run with a T1-sensitive three-dimensional (3D) gradient-echo (GRE) sequence using cerebral blood volume (CBV) contrast after intravenous administration of a contrast agent containing a chelate of gadolinium diethylene-triamine-pentaacetate with a phosphono-oxymethyl substituent. All sequences were performed during the execution of a block-type finger-tapping paradigm. SPM5 software was used for statistical analysis. For both runs maximum activations (peak Z-score = 5.5, cluster size 3,449 voxels) were localized in the left postcentral gyrus. Visual inspection of respective signal amplitudes suggests the T1 contrast to be substantially smaller than EPI (0.5% vs 1%). A new functional imaging method with potentially smaller image artefacts due to the nature of CBV contrast and characteristics of the T1 sequence was proposed and verified.

Basal Cerebral Blood Volume during the Poststimulation Undershoot in BOLD MRI of the Human Brain

“…In this respect, these results provide evidence against the assumption that the specific nature of the contrast agent might be responsible for the conflicting results. Although Vasovist is based on gadolinium rather than on iron oxide particles as used for most animal studies, it temporarily binds to the blood albumin and also acts as a blood-pool contrast agent (Blockley et al, 2008;Majos et al, 2009;Morton et al, 2006). To which degree interspecies differences and/or influences from anesthesia have a role cannot be answered at this stage.…”

“…One possible reason for these discrepancies is a methodological difference as most of the animal studies are based on blood-pool contrast agents with iron oxide particles (Jin and Kim, 2008;Kennan et al, 1998;Kida et al, 2007;Kim et al, 2007;Mandeville et al, 1998Mandeville et al, , 1999aSmirnakis et al, 2007). Thus, to investigate the impact of the specific contrast agent used for assessing CBV effects, we set up an experiment using dynamic T1-weighted three-dimensional (3D) MRI and the blood-pool contrast agent Vasovist, containing gadofosveset trisodium (Majos et al, 2009;Morton et al, 2006). Vasovist binds to blood albumin and stays in the vascular system in sufficient concentration for B1 hour after injection.…”

Is it possible to measure hemodynamic changes in the prefrontal cortex through the frontal sinus using continuous wave DOT systems?

“…The above technique for measuring cerebral inflow compares the signal intensity of voxels before and after the injection of a known contrast agent. The signal drop is directly related to the concentration of the contrast agent in the blood pool [42]. The results show that the max.…”

A blood pool contrast aided T1 functional MRI in patients with brain tumors—a preliminary study

“…Since the possibility of applying the T1 CBV technique was previously demonstrated during laboratory studies and in healthy volunteers [16], a control group was not included in this study. Although their cohort was small, Ben Bashat et al [17] achieved satisfactory results during CBV evaluation of brain tumor patients using routinely applied gadolinium chelates with a mean distribution half-life of about 0.2 h (www.imaging.bayerhealthcare.com/html/magnevist).…”