Combined perfusion- and diffusion-weighted MR imaging in acute ischemic stroke during the 1st week: a longitudinal study.

PURPOSE: To compare findings with different magnetic resonance (MR) perfusion maps in acute ischemic stroke. MATERIALS AND METHODS: Combined diffusion-weighted (DW) and perfusion-weighted (PW) MR imaging was performed in 49 patients with acute (<24 hours) stroke, on the 1st and 2nd days and 1 week after stroke. Volumes of hypoperfused tissue on maps of relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and mean transit time (MTT) were compared with the volume of infarcted tissue at DW imaging. RESULTS: The mean infarct volume increased from 41 to 65 cm(3) between the 1st and 2nd days (P: <.001; n = 49). On the 1st day, all perfusion maps on average showed hypoperfusion lesions larger than the infarct at DW imaging (P: <.001; n = 49). MTT maps showed significantly (P: <.001) larger hypoperfusion lesions than did rCBF maps, which showed significantly (P: <.001) larger hypoperfusion lesions than did rCBV maps. The sizes of the initial perfusion-diffusion mismatches correlated significantly with the extent of infarct growth (0.479 < r < 0.657; P:

Cerebral hemodynamics in human acute ischemic stroke: a study with diffusion- and perfusion-weighted magnetic resonance imaging and SPECT.

Nineteen patients with acute ischemic stroke (<24 hours) underwent diffusion-weighted and perfusion-weighted (PWI) magnetic resonance imaging at the acute stage and 1 week later. Eleven patients also underwent technetium-99m ethyl cysteinate dimer single-photon emission computed tomography (SPECT) at the acute stage. Relative (ischemic vs. contralateral control) cerebral blood flow (relCBF), relative cerebral blood volume, and relative mean transit time were measured in the ischemic core, in the area of infarct growth, and in the eventually viable ischemic tissue on PWI maps. The relCBF was also measured from SPECT. There was a curvilinear relationship between the relCBF measured from PWI and SPECT (r = 0.854; P < 0.001). The tissue proceeding to infarction during the follow-up had significantly lower initial CBF and cerebral blood volume values on PWI maps (P < 0.001) than the eventually viable ischemic tissue had. The best value for discriminating the area of infarct growth from the eventually viable ischemic tissue was 48% for PWI relCBF and 87% for PWI relative cerebral blood volume. Combined diffusion and perfusion-weighted imaging enables one to detect hemodynamically different subregions inside the initial perfusion abnormality. Tissue survival may be different in these subregions and may be predicted.

Regional cerebral blood flow during exposure to food in obese binge eating women.

Cerebral responses elicited by the sight of food were evaluated in eight obese binge eating, 11 obese and 12 normal-weight non-binge eating women. Regional cerebral blood flow (rCBF) was mapped while the subjects were looking at a picture of a landscape (control) or at a portion of food (food exposure), and was measured by [99mTc]ethyl-cysteine-dimer and single photon emission computed tomography. Exposure to food was associated with different changes in the cerebral blood flow (normalized to mean cerebellar counts) of the right and left hemispheres in the obese binge eating than in the obese or normal-weight non-binge eating women. As compared with the non-binge eating groups, the obese binge eating women had, due to food exposure, a greater increase in the cerebral blood flow in the left than right hemisphere, especially in the frontal and pre-frontal regions. In addition, strong linear correlations were observed in this group between the rCBF of the left frontal and pre-frontal regions and the increase in the feeling of hunger during the exposure to food. Left hemisphere and its frontal and pre-frontal regions could thus play a role in binge eating behavior in humans.

Combined SPECT and diffusion-weighted MRI as a predictor of infarct growth in acute ischemic stroke.

UNLABELLED: In acute ischemic stroke, the infarcted core is surrounded by a zone of tissue that has decreased perfusion. Some of this tissue may be salvaged by prompt, effective treatment. Diffusion-weighted MRI is sensitive in detecting the infarcted tissue, whereas SPECT also detects the hypoperfused tissue around the infarcted core. We studied the potential of combined diffusion-weighted MRI and SPECT to predict infarct growth and clinical outcome in patients not receiving thrombolytic treatment. METHODS: Sixteen patients with acute stroke were examined consecutively with diffusion-weighted MRI and 99mTc-ethyl cysteinate dimer (99mTc-ECD) SPECT within 24 h of the onset of symptoms. Follow-up diffusion-weighted MRI was performed on the second day and after 1 wk. The volumes of infarcted and hypoperfused brain tissue were measured from diffusion-weighted MRI and SPECT, respectively. The volume difference between the hypoperfused and infarcted tissue on the first day was compared with the possible increase in infarct volume during the follow-up. Each patient's neurologic status was assessed with the National Institutes of Health Stroke Scale (NIHSS). RESULTS: The volume of infarcted tissue increased from 48 +/- 54 cm3 (mean +/- SD) on the first day to 88 +/- 93 cm3 on the second day (P = 0.001) and to 110 +/- 121 cm3 at 1 wk (P = 0.001). The volume of hypoperfused tissue on the first day was significantly greater than the infarct volume (102 +/- 135 cm3; P = 0.001). The volume difference between the hypoperfused and infarcted tissue on the first day correlated significantly with the infarct growth between the first day and 1 wk (r = 0.71; P < 0.01). Between the first day and 1 wk, the increase of the infarct volume correlated significantly with the change in the NIHSS (r = 0.54; P < 0.05). CONCLUSION: A large hypoperfusion zone around the infarct core in the acute phase of ischemic stroke predicts the infarct growth during the first week, and this correlates significantly with the change in the neurologic status of the patient. Combined diffusion-weighted MRI and SPECT performed within 24 h after the onset of symptoms can be useful in the evaluation of acute stroke to predict infarct growth.

Combined diffusion and perfusion MRI with correlation to single-photon emission CT in acute ischemic stroke. Ischemic penumbra predicts infarct growth.

BACKGROUND AND PURPOSE: More effective imaging methods are needed to overcome the limitations of CT in the investigation of treatments for acute ischemic stroke. Diffusion-weighted MRI (DWI) is sensitive in detecting infarcted brain tissue, whereas perfusion-weighted MRI (PWI) can detect brain perfusion in the same imaging session. Combining these methods may help in identifying the ischemic penumbra, which is an important concept in the hemodynamics of acute stroke. The purpose of this study was to determine whether combined DWI and PWI in acute (<24 hours) ischemic stroke can predict infarct growth and final size. METHODS: Forty-six patients with acute ischemic stroke underwent DWI and PWI on days 1, 2, and 8. No patient received thrombolysis. Twenty-three patients underwent single-photon emission CT in the acute phase. Lesion volumes were measured from DWI, SPECT, and maps of relative cerebral blood flow calculated from PWI. RESULTS: The mean volume of infarcted tissue detected by DWI increased from 46.1 to 75.6 cm(3) between days 1 and 2 (P<0.001; n=46) and to 78.5 cm(3) after 1 week (P<0.001; n=42). The perfusion-diffusion mismatch correlated with infarct growth (r=0. 699, P<0.001). The volume of hypoperfusion on the initial PWI correlated with final infarct size (r=0.827, P<0.001). The hypoperfusion volumes detected by PWI and SPECT correlated significantly (r=0.824, P<0.001). CONCLUSIONS: Combined DWI and PWI can predict infarct enlargement in acute stroke. PWI can detect hypoperfused brain tissue in good agreement with SPECT in acute stroke.

Serum leptin and regional cerebral blood flow during exposure to food in obese and normal-weight women.

Leptin is an adipocyte-derived product of the ob gene thought to be involved in the regulation of eating. Receptors for leptin have been found in multiple regions in the brain. In particular, hypothalamic receptors seem to be of fundamental importance for the biological effects of leptin. However, the association of leptin with cerebral function in humans has not been studied. Therefore, in order to assess the possible functional relationships between leptin and cerebral activity in humans, simultaneous serum leptin and regional cerebral blood flow (rCBF) measurements were made in 10 obese [BMI 33.5 (29.3-39.1) kg/m2] and 12 normal-weight [BMI 22.2 (20.3-24.6) kg/m2] women during exposure to food. The rCBF measurements were performed by 99mTc-ethyl-cysteine-dimer single photon emission computed tomography. A strong inverse association was observed between the leptin and rCBF of hypothalamus during the exposure to food in the obese (r = -0.73, p = 0.02, n = 10), but not in the normal-weight subjects (r = 0.22, p = 0.48, n = 12). This suggests that the association of leptin with cerebral activity could be different in obese and normal-weight women; depressed activity of hypothalamic neurones in response to the high peripheral leptin concentration could be postulated to occur in obese women during exposure to food.

Regional cerebral blood flow during food exposure in obese and normal-weight women.

The cerebral responses elicited by the sight of food and food-related cues are poorly known in humans. Therefore, regional cerebral blood flow (rCBF) was measured during food exposure in 11 obese and 12 normal-weight women. The rCBF was mapped while the subject was looking at a picture of a landscape (control) or at a portion of food (food exposure), and was measured by 99mTc-ethyl-cysteine-dimer single photon emission computed tomography. In the obese women, the rCBF was higher in the right parietal and temporal cortices during the food exposure than in the control condition. In addition, in the obese women the activation of the right parietal cortex was associated with an enhanced feeling of hunger when looking at food. No such changes or associations were seen in the normal-weight women. In conclusion, exposure to food is associated with increases in the rCBF of right parietal and temporal cortices in obese women, but not in normal-weight women.