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Biomedical subjects

S T Engelter

Publications and source records attributed to S T Engelter.

7 recordsLinked to original sources
PubMed2001

Use of exponential diffusion imaging to determine the age of ischemic infarcts.

OBJECTIVE: Diffusion-weighted magnetic resonance imaging (DWI) detects acute ischemic infarcts with high lesion conspicuity. Determination of infarct age is difficult on DWI alone because infarct signal intensity (SIinfarct) on DWI is influenced by T2 properties ("T2 shine-through"). Maps of the apparent diffusion coefficient (ADC) reflect pure diffusion characteristics without T2 effects but have low lesion conspicuity. Thus, in clinical practice, combined use of DWI and ADC maps is required. Exponential DWI (eDWI) is an innovative means of MRI-diffusion data analysis that merges the advantages of DWI and ADC maps. The authors hypothesized that SIinfarct on eDWI would correlate with infarct age. The authors studied 114 consecutive patients who had 120 ischemic strokes with clearly determined onset times and who underwent echo-planar DWI. The eDWI were generated by dividing the signal intensity on DWI by that on the corresponding T2 image on a pixel-by-pixel basis. SIinfarct on eDWI was measured in the lesion core and expressed as a percentage of contralateral control tissue. On eDWI, relative SIinfarct changed significantly with infarct age (P < .0001). When patients were sorted in infarct-age groups, no significant differences were found within the first 120 hours. However, for patients studied within 5 days, the mean relative SIinfarct was significantly higher compared with patients studied > or = 8 days after stroke (P < .05). For all infarcts up to 5 days old, the eDWI signal intensity was higher than control tissue (hyperintense appearance). All infarcts > 10 days old had an eDWI signal intensity lower than control tissue (hypointense appearance). The authors concluded that the use of eDWI, as a single set of images, reliably differentiates acute infarcts (< or = 5 days old) from infarcts > 10 days old. This feature would be expected to be helpful when the distinction between acute and nonacute infarction cannot be determined on clinical grounds.

Adolescent↗
PubMed2000

Assessment of vasogenic edema in eclampsia using diffusion imaging.

We qualitatively assessed the regional distribution of vasogenic edema in a case of postpartum eclampsia. Although diffusion-weighted imaging showed no abnormalities, bilateral high signal was seen on T2-weighted images and apparent diffusion coefficient (ADC) maps. ADC of 1.45 +/- 0.10 mm2/s x 10(-3) for the posterior cerebral artery (PCA) territory and 1.22 +/- 0.12 mm2/s x 10(-3) for the watershed areas were significantly higher than those in the territories of the anterior (0.85 +/- 0.07 mm2/s x 10(-3) and middle cerebral (0.79 +/- 0.06 mm2/s x 10(-3)) arteries (P < 0.05). The predilection of ADC changes within the PCA territory and in a previously undescribed watershed distribution supports the hypothesis that vasogenic edema in eclampsia is due to hypertension-induced failure of vascular autoregulation.

Adult↗
PubMed2000

Long-term follow-up after extracranial internal carotid artery dissection.

OBJECTIVE: To evaluate long-term outcome after extracranial internal carotid artery dissection (eICAD) in consideration of the applied antithrombotic therapy. MATERIAL AND METHODS: Among 33 consecutive eICAD patients initially treated either with anticoagulation (n = 25) or with antiplatelets (n = 8), a standardized interview was performed after 28 +/- 22.1 months to analyze risks and benefits of both agents. Ischemic and hemorrhagic complications, occurrence of seizure and rates of arterial recanalization were compared and long-term clinical outcome was assessed using the modified Rankin Scale (mRS) and Barthel Index (BI). RESULTS: Among anticoagulated patients, 1 died due to brain herniation. In 3 patients stroke (n = 2) or TIA (n = 1) recurred. In the antiplatelet group, none died and no subsequent ischemic events happened. Hemorrhagic complications were noted in neither treatment group. Functional outcome among anticoagulated patients was BI 92 +/- 21.6 and mRS 1.48 +/- 1.50, which did not differ from patients initially treated with antiplatelets (BI 89 +/- 18.9, mRS 1.50 +/- 1.41, p > 0.05). Four anticoagulated patients developed seizures, compared to 2 patients with antiplatelets (p > 0.05). Arterial recanalization occurred in 16 of 22 antico- agulated patients with ultrasound follow-up, compared to 6 of 6 patients with antiplatelets (p > 0.05). CONCLUSION: In the absence of iatrogenic side effects, both anticoagulation and antiplatelets seem to be safe for eICAD. The rates for death and stroke were low and outcome ratings did not differ between both agents. These findings may indicate that a controlled randomized trial comparing anticoagulation and antiplatelets is ethically justified.

Adult↗
PubMed2000

The effect of aging on the apparent diffusion coefficient of normal-appearing white matter.

OBJECTIVE: The purpose of our study was to test the hypothesis that the apparent diffusion coefficient (ADC) of normal-appearing white matter increases with advancing age. SUBJECTS AND METHODS: We selected 38 patients with normal MR imaging findings from 332 patients undergoing clinical MR imaging. Diffusion-weighted MR imaging was performed with diffusion gradients applied in three orthogonal directions. For each patient, the average ADC on trace-weighted diffusion images of white matter at prespecified regions of interest and at the thalamus were compared with the patient's age. RESULTS: For the white matter, ADC sorted by patient age in decades increased with advancing age. Patients at least 60 years old had significantly higher ADC (0.769 +/- 0.019 mm(2)/sec x 10(-3)) than patients less than 60 years old (0.740 +/- 0.013 mm(2)/sec x 10(-3)) (p < 0.001). Comparison of individual white matter ADC and age showed a significant increase with advancing age (p < 0.0001). For the thalamus, the average ADC among patients at least 60 years old (0.766 +/- 0.015 mm(2)/sec x 10(-3)) exceeded the average ADC for patients less than 60 years old (0.745 +/- 0.022 mm(2)/sec x 10(-3)) (p < 0.05). However, comparison of individual thalamic ADC and patient ages, although showing a trend to higher ADC with increasing age, did not reach statistical significance (p = 0.06). CONCLUSION: Advancing age is associated with a small but statistically significant increase of water diffusibility in human white matter. A similar trend was present in the thalamus. These increases may reflect mild structural changes associated with normal aging.

Adult↗