Biomedical subjects

Stefanie Meisel

Publications and source records attributed to Stefanie Meisel.

3 recordsLinked to original sources

PubMed2006

Significance of the perfusion-diffusion mismatch in chronic cerebral ischemia.

PURPOSE: To determine whether the perfusion deficit could predict brain infarction in patients with chronic cerebral ischemia who experienced recurring episodes of neurological symptoms and showed a perfusion-diffusion mismatch on magnetic resonance (MR) images. MATERIALS AND METHODS: In 53 consecutive patients (38 males and 15 females, 62+/-13 years old) with ischemia in the middle cerebral artery (MCA) territory, lesion volumetry was performed on parametric maps of the time-to-peak, the cerebral blood volume, and diffusion-weighted (DW) images. The infarct lesions were assessed on follow-up T2-weighted (T2W) MR images after eight days. Cerebrovascular changes were determined by time-of-flight (TOF) MR angiography (MRA). Inferential and correlation statistics were used. RESULTS: Patients with chronic ischemic brain disease (N=39) who presented with a severe perfusion-diffusion mismatch in the presence of a normal cerebral blood volume had no or small brain infarctions as found on follow-up T2W images. MRA revealed widespread abnormalities of the basal cerebral arteries compatible with brain perfusion abnormalities. In contrast, in acute stroke patients (N=14) the deficit of cerebral perfusion predicted the infarct lesion in the T2W images. CONCLUSION: Our results suggest that in chronic cerebral ischemia the normal blood volume was maintained despite the depression of cerebral perfusion and recurring minor insults.

Adult↗

PubMed2005

Initial ischemic event: perfusion-weighted MR imaging and apparent diffusion coefficient for stroke evolution.

PURPOSE: To prospectively determine if the degree of acute perfusion or diffusion abnormalities measured prior to treatment onset help predict the evolution of brain infarction on magnetic resonance (MR) images. MATERIALS AND METHODS: Local ethics committee approval and informed consent were obtained. On parametric maps obtained in 64 patients (mean age, 64 years +/- 13 [standard deviation]; 37 men and 27 women) with acute middle cerebral artery infarction, lesion volumetry was performed to determine time to peak, mean transit time, cerebral blood volume, and apparent diffusion coefficient obtained within 3 hours of symptom onset. The infarct lesions were assessed on T2-weighted MR images obtained at follow-up on day 8. Cerebrovascular changes were determined on MR angiograms. Inferential and correlation statistics were used. RESULTS: A perfusion delay of more than 6 seconds relative to the nonaffected hemisphere on time-to-peak maps helped to predict the lesion volume on T2-weighted images (r = 0.686, P < .001). In contrast, neither the volume nor the degree of the diffusion abnormality helped to predict the infarct volume (r < 0.46). This was because in one subgroup of patients there was an increase and in one subgroup there was a decrease in infarct volume on the T2-weighted images (P < .001). There was a greater prevalence (P < .02) of cerebral artery abnormalities in the patients with larger infarcts. Clinically, the neurologic impairment was more severe (P < .01) and the mean arterial pressure higher (P < .04) in these patients. CONCLUSION: The results suggest that in acute stroke the severity of the initial ischemic event as determined on time-to-peak maps indicates hemodynamic compromise in addition to internal carotid artery or middle cerebral artery occlusion, because of abnormalities in other cerebral arteries.

Adult↗

PubMed2005

Partial rescue of the perfusion deficit area by thrombolysis.

PURPOSE: To investigate the evolution of the perfusion deficit area following systemic thrombolysis with recombinant tissue plasminogen activator (rtPA) in a clinical study on acute cerebral ischemia. MATERIALS AND METHODS: We performed volumetric measurements of the acute ischemic lesions in MR images of perfusion (TTP, MTT, and rCBV) and in diffusion-weighted (DW) images, as well as the manifest stroke lesions in T2-weighted MR images on day 8. We compared the data of 29 patients who were subjected to systemic thrombolysis with those of 18 patients who were not eligible for thrombolysis. RESULTS: In the treated patients there were prominent MTT/DWI and TTP/DWI mismatches (P < 0.0006). The acute TTP volumes were smaller than the acute MTT volumes, but as large as the T2 lesions on day 8. The MTT/T2 lesion volume reduction was significant (P < 0.03) in patients who received the GPIIb/IIIa receptor antagonist tirofiban (N = 13) in addition to the low-dose rtPA. This corresponded to a greater neurological improvement compared to patients who received rtPA alone (P < 0.05). In contrast, in the nontreated patients the initial MTT and TTP lesion volumes were of similar magnitude and predicted the T2 lesions on day 8. In the treated and nontreated patients the TTP lesion signified the viability threshold of acute ischemia, which corresponded to a rCBF of 25 +/- 11 mL/100 g/min. CONCLUSION: The perfusion deficit area comprises the ischemic core that is destined to undergo necrosis, and an ischemic rim that is salvageable by systemic thrombolysis.

Adult↗