Influence of Arterial Input Function on Hypoperfusion Volumes Measured with Perfusion-Weighted Imaging

Stanford University, Palo Alto, California, United States
Stroke (Impact Factor: 5.72). 02/2004; 35(1):94-8. DOI: 10.1161/01.STR.0000106136.15163.73
Source: PubMed


The arterial input function (AIF) is critical in determining hemodynamic parameters quantitatively with bolus-tracking MRI. We studied the effect of varying the location of measurement of AIF on the volume of hypoperfusion. We compared the volumes of hypoperfusion obtained with different AIFs with the final ischemic lesion volume.
We included 13 patients with acute cerebral ischemia in the anterior circulation who underwent diffusion- (DWI) and perfusion (PWI)-weighted imaging within 8 hours after symptom onset and exhibited DWI lesion expansion between baseline and follow-up. AIF was measured at 4 locations: near both middle cerebral arteries (MCAs), in MCA branches adjacent to the largest DWI abnormality, and at the same level on the opposite hemisphere. Hypoperfusion lesion volumes were compared with the DWI volume at follow-up.
Large variations in PWI lesion size were found with different AIF locations. The largest PWI lesions were found when AIF was measured at the contralateral MCA. Smaller PWI lesions were found when AIF was measured in the other locations. There was no significant difference between PWI lesion area at baseline and follow-up DWI lesion when AIF was measured at the contralateral MCA. The other PWI lesions significantly underestimated follow-up DWI lesion size.
AIF is an important determinant of the size of hypoperfusion lesions measured with PWI. PWI lesion volumes determined with AIF from the contralateral MCA are associated with follow-up lesion volume.

Download full-text


Available from: Diederik Somford, Mar 23, 2014
  • Source
    • "The type of deconvolution (Ostergaard et al, 1996; Wu et al, 2003) as well as the placement of the AIF (Ebinger et al, 2010a; Thijs et al, 2004) lack a standardized definition across the imaging facilities. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In ischemic stroke, positron-emission tomography (PET) established the imaging-based concept of penumbra. It defines hypoperfused, but functionally impaired, tissue with preserved viability that can be rescued by timely reperfusion. Diffusion-weighted and perfusion-weighted (PW) magnetic resonance imaging (MRI) translated the concept of penumbra to the concept of mismatch. However, the use of mismatch-based patient stratification for reperfusion therapy remains a matter of debate. The equivalence of mismatch and penumbra, as well as the validity of the classical mismatch concept is questioned for several reasons. First, methodological differences between PET and MRI lead to different definitions of the tissue at risk. Second, the mismatch concept is still poorly standardized among imaging facilities causing relevant variability in stroke research. Third, relevant conceptual issues (e.g., the choice of the adequate perfusion measure, the best quantitative approach to perfusion maps, and the required size of the mismatch) need further refinement. Fourth, the use of single thresholds does not account for the physiological heterogeneity of the penumbra and probabilistic approaches may be more promising. The implementation of this current knowledge into an optimized state-of-the-art mismatch model and its validation in clinical stroke studies remains a major challenge for future stroke research.
    Full-text · Article · Apr 2012 · Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism
  • Source
    • "TTP represents the time at which the largest signal drop occurs in the signal intensity curve with respect to the first image. TTP maps are generated directly from the signal intensity curves and do not rely on deconvoluting algorithms or the choice of adequate input functions (Thijs et al., 2004; Calamante, Gadian, & Connelly, 2002). In order to identify common regions of perfusion abnormality in the two groups of patients, the PWI volumes were spatially realigned and then transferred into stereotaxic space using the spatial normalization algorithm provided by SPM2. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Visual extinction is an intriguing defect of awareness in stroke patients, referring to the unsuccessful perception of contralesional events under conditions of competition. Previous studies have investigated the cortical and subcortical brain structures that, when damaged or inactivated, provoke visual extinction. The present experiment asked how lesions of subcortical structures may contribute to the appearance of visual extinction. We investigated whether lesions centering on right basal ganglia may induce dysfunction in distant, structurally intact cortical structures. Normalized perfusion-weighted MRI was used to identify structurally intact but abnormally perfused brain tissue, that is, zones that are receiving enough blood supply to remain structurally intact but not enough to function normally. We compared patients with right basal ganglia lesions showing versus not showing visual extinction. In the extinction patients, the contrast revealed cortical malperfusion that clustered around the right TPJ. It seems as if malfunction of this area is a critical aspect in visual extinction not only after cortical lesion but also in the case of subcortical basal ganglia damage. Our results support the idea that a normally functioning TPJ area plays a decisive role for the attentional network involved in detecting of visual stimuli under conditions of competition.
    Full-text · Article · Aug 2009 · Journal of Cognitive Neuroscience
  • Source
    • "The time-to-peak (TTP) represents the time at which the largest signal drop occurs in the signal intensity curve with respect to the first image. TTP maps are generated directly from the signal intensity curves and do not rely on deconvoluting algorithms or the choice of adequate input functions (Calamante et al., 2002; Thijs et al., 2004). A further marker for abnormal perfusion is the amount of blood flow reaching the different regions of the brain. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent studies have suggested a tightly connected perisylvian neural network associated with spatial neglect. Here we investigated whether structural damage in one part of the network typically is accompanied with functional damage in other, structurally intact areas of this network. By combining normalized fluid-attenuated inversion-recovery (FLAIR) imaging, diffusion-weighted imaging (DWI), and perfusion-weighted imaging (PWI) we asked whether or not lesions centering on fronto-temporal regions co-occur with abnormal perfusion in structurally intact parietal cortex. With thresholds applied to delineate behaviourally relevant malperfusion of brain tissue, the analysis of normalized time-to-peak (TTP) and maximal signal reduction (MSR) perfusion maps did not reveal significant changes outside the area of structural damage. In particular, we found no abnormal perfusion in the structurally intact inferior parietal lobule (IPL) and/or the temporo-parietal junction (TPJ). The present results obtained in three consecutively admitted neglect patients with fronto-temporal lesions indicate that structural damage in one part of the right perisylvian network associated with spatial neglect does not necessarily require dysfunction by malperfusion in other, structurally intact parts of the network to provoke spatial neglect. The neural tissue in the fronto-temporal cortex appears to have an original role in processes of spatial orienting and exploration.
    Full-text · Article · Feb 2009 · Frontiers in Human Neuroscience
Show more