Arterial spin-labeling MR imaging measurements of timing parameters in patients with a carotid artery occlusion.
ABSTRACT Arterial spin-labeling (ASL) with image acquisition at multiple delay times can be exploited in perfusion MR imaging to visualize and quantify the temporal dynamics of arterial blood inflow. In this study, we investigated the consequences of an internal carotid artery (ICA) occlusion and collateral blood flow on regional timing parameters.
Seventeen functionally independent patients with a symptomatic ICA occlusion (15 men, 2 women; mean age, 57 years) and 29 sex- and age-matched control subjects were investigated. ASL at multiple delay times was used to quantify regional cerebral blood flow (CBF) and the transit and trailing edge times (arterial timing parameters) reflecting, respectively, the beginning and end of the labeled bolus. Intra-arterial digital subtraction angiography and MR angiography were used to grade collaterals.
In the hemisphere ipsilateral to the ICA occlusion, the CBF was lower in the anterior frontal (31 +/- 4 versus 47 +/- 3 mL/min/100 g, P < .01), posterior frontal (39 +/- 4 versus 55 +/- 2 mL/min/100 g, P < .01), and frontal parietal region (49 +/- 3 versus 61 +/- 3 mL/min/100 g, P = .04) than that in control subjects. The trailing edge of the frontal-parietal region was longer in the hemisphere ipsilateral to the ICA occlusion compared with that in control subjects (2225 +/- 167 versus 1593 +/- 35 ms, P < .01). In patients with leptomeningeal collateral flow, the trailing edge was longer in the anterior frontal region (2436 +/- 275 versus 1648 +/- 201 ms, P = .03) and shorter in the occipital region (1815 +/- 128 versus 2388 +/- 203 ms, P = .04), compared with patients without leptomeningeal collaterals.
Regional assessment of timing parameters with ASL may provide valuable information on the cerebral hemodynamic status. In patients with leptomeningeal collaterals, the most impaired territory was found in the frontal lobe.
Article: Assessment of cortical hemodynamics by multichannel near-infrared spectroscopy in steno-occlusive disease of the middle cerebral artery.[show abstract] [hide abstract]
ABSTRACT: In a pilot study we evaluated near-infrared spectroscopy as to its potential benefit in monitoring patients with steno-occlusive disease of a major cerebral artery for alterations in cortical hemodynamics. Cortical maps of time-to-peak (TTP) in 10 patients unilaterally affected by severe stenosis or occlusion of the middle cerebral artery were acquired by multichannel near-infrared spectroscopy after bolus application of indocyanine green. Hemodynamic manifestations were assessed by comparison between affected and unaffected hemisphere and evaluated for common constituents by principal component analysis. In one patient, TTP values were compared with those obtained by dynamic susceptibility contrast imaging. TTP was increased on the affected hemisphere in 9 patients. Mean difference in TTP between hemispheres was 0.44 second (P<0.05) as compared with a mean lateral difference of 0.12 second found in a control group of 10 individuals. In group analysis a significant rise in TTP was found in the distribution of the affected middle cerebral artery, whereas principal component analysis suggests augmentation of hemodynamic effects toward the border zones as a dominant pattern. A linear correlation of 0.61 between TTP values determined by dynamic susceptibility contrast MRI and near-infrared spectroscopy was found to be statistically significant (P<0.001). Multichannel near-infrared spectroscopy might facilitate detection of disease-related hemodynamic changes as yet only accessible by tomographic imaging modalities. Being indicative for hypoperfusion and collateral flow increased values of TTP, as found to a varying extent in the present patient group, might be of clinical relevance.Stroke 11/2012; 43(11):2980-5. · 5.73 Impact Factor