Secondary decline in apparent diffusion coefficient and neurological outcomes after a short period of focal brain ischemia in rats

Self Cite

132

164

Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) can rapidly detect lesions in acute ischemic stroke patients. The PWI volume is typically substantially larger than the DWI volume shortly after onset, that is, a diffusion/ perfusion mismatch. The aims of this study were to follow the evolution of the diffusion/ perfusion mismatch in permanent and 60- minute temporary focal experimental ischemia models in Sprague-Dawley rats using the intraluminal middle cerebral artery occlusion (MCAO) method. DWI and arterial spin-labeled PWI were performed at 30, 60, 90, 120, and 180 minutes after occlusion and lesion volumes (mm(3)) calculated At 24 hours after MCAO, and infarct volume was determined using triphenyltetrazolium chloride staining. In the permanent MCAO group, the lesion volume on the ADC maps was significantly smaller than that on the cerebral blood flow maps through the first 60 minutes after MCAO; but not after 90 minutes of occlusion. With 60 minutes of transient ischemia, the diffusion/perfusion mismatch was similar, but after reperfusion, the lesion volumes on ADC and cerebral blood flow maps became much smaller. There was a significant difference in 24- hour infarct volumes between the permanent and temporary occlusion groups.

Section: Discussionsupporting

confidence: 89%

“…In the reperfusion group, the ADC‐defined lesion volume at 3 hours tended to underestimate the 24‐hour, TTC‐derived lesion volume. We attribute this observation to the likely occurrence of secondary, reperfusion injury that evolves over many hours,22, 27, 32 resulting in concomitantly larger ischemic lesion volumes at postmortem.…”

Section: Discussionmentioning

confidence: 90%

Characterizing the diffusion/perfusion mismatch in experimental focal cerebral ischemia

Meng

Fisher

Shen

et al. 2003

Self Cite

132

164

“…DWI studies in animal models have demonstrated a decline in brain ADC values during arrest, which reverses during resuscitation 19–21. Despite successful reperfusion, however, secondary energy failure and ADC decrease often occur after several hours 22. Our observations support the notion that DWI changes induced by global hypoxic cerebral injury in humans evolve slowly and peak around 2 to 4.5 days after the arrest.…”

Section: Discussionsupporting

confidence: 76%

Prognostic value of brain diffusion‐weighted imaging after cardiac arrest

Wijman

Mlynash

Caulfield

et al. 2009

239

187

Objective-Outcome prediction is challenging in comatose post-cardiac arrest survivors. We assessed the feasibility and prognostic utility of brain diffusion-weighted MRI (DWI) during the first week.Corresponding Author Christine AC Wijman, MD, PhD, Stanford Stroke Center, 701 Welch Road, B325, Palo Alto, CA 94304, Fax: (650) Tel: (650) NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptMethods-Consecutive comatose post-cardiac arrest patients were prospectively enrolled. MRI data of patients who met predefined specific prognostic criteria were used to determine distinguishing ADC thresholds. Group 1: death at 6 months and absent motor response or absent pupillary reflexes or bilateral absent cortical responses at 72 hours, or vegetative at 1 month. Group 2A: Glasgow outcome scale (GOS) score of 4 or 5 at 6 months. Group 2B: GOS of 3 at 6 months. The percentage of voxels below different apparent diffusion coefficient (ADC) thresholds was calculated at 50 × 10 −6 mm 2 /sec intervals.Results-Overall, 86% of patients underwent MR imaging. Fifty-one patients with 62 brain MRIs were included in the analyses. Forty patients met the specific prognostic criteria. The percentage of brain volume with an ADC value below 650-700 × 10 −6 mm 2 /sec best differentiated between group 1 and groups 2A and 2B combined (p<0.001), while the 400-450 × 10 −6 mm 2 /sec threshold best differentiated between groups 2A and 2B (p=0.003). The ideal time window for prognostication using DWI was between 49 to 108 hours after the arrest. When comparing MRI in this time window with the 72 hour neurological examination MRI improved the sensitivity for predicting poor outcome by 38% while maintaining 100% specificity (p=0.021).Interpretation-Quantitative DWI in comatose post-cardiac arrest survivors holds great promise as a prognostic adjunct.Approximately 350,000 cardiac arrests occur annually in the United States1. Up to half of these patients are successfully resuscitated. In the past, only 10% to 30% of comatose postcardiac arrest patients had good functional recovery. These numbers will likely improve with the increasing use of therapeutic hypothermia2 , 3.Post-cardiac arrest brain injury is a common cause of morbidity and mortality. Many comatose post-cardiac arrest patients die or survive with severe disability after a prolonged intensive care unit stay associated with a tremendous cost burden4 , 5. Conversely, the potential for premature withdrawal of life support from patients who may have a chance of functional recovery represents an additional ethical dilemma. Thus, early accurate identification of patients who have no likelihood of meaningful recovery is a very important health care issue.Although several prognostic variables have been studied in comatose post-cardiac arrest patients, the currently accepted variables (neurological examination, neurophysiologic tests, and serum markers) have substantive limitations. First, they identify only a subset of poor outcome patients with high specificity. Se...

“…In rabbits, there is a shorter ADC decline and a shorter period for ADC normalization (1–3 days). Because these changes are also observed in rodents26 differences in these animals can be attributed to faster maturation and development compared with humans. One limitation of human studies is that all these studies involve postnatal MRI.…”

Section: Discussionmentioning

confidence: 97%

Fetal brain magnetic resonance imaging response acutely to hypoxia‐ischemia predicts postnatal outcome

Drobyshevsky

Derrick

Prasad

et al. 2007