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Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia
Published on: September 20, 2015
Diffusion-weighted imaging in the evaluation of watershed hypoxic-ischemic brain injury in pediatric patients
A Y Liu1, R A Zimmerman, J C Haselgrove
1Department of Radiology, The Children's Hospital of Philadelphia, PA 19104, USA.
Insights
Echo-planar diffusion-weighted imaging (EPDI) effectively detects pediatric watershed hypoxic-ischemic brain injury. This rapid MRI technique identifies changes earlier than conventional methods, aiding in timely diagnosis and management of these critical conditions.
Area of Science:
- Pediatric Neurology
- Neuroradiology
- Diffusion-Weighted Magnetic Resonance Imaging
Background:
- Watershed hypoxic-ischemic brain injury is a significant concern in pediatric patients.
- Conventional MRI may not always detect early ischemic changes effectively.
- Timely diagnosis is crucial for appropriate management and improved outcomes.
Purpose of the Study:
- To evaluate the utility of echo-planar diffusion-weighted imaging (EPDI) for diagnosing watershed hypoxic-ischemic brain injury in children.
- To compare the sensitivity of EPDI with conventional MRI sequences in detecting these injuries.
- To assess the role of apparent diffusion coefficients (ADC) in characterizing these lesions.
Main Methods:
- Retrospective analysis of 18 pediatric patients with suspected watershed hypoxic-ischemic injury.
- Conventional MRI (T1, T2, FLAIR) followed by EPDI with multiple b-values.
- Analysis of signal abnormalities and ADC values in ischemic/infarction zones.
- Comparison of EPDI findings with conventional MRI and clinical presentation.
Main Results:
- EPDI detected abnormal signal in watershed ischemic/infarction zones in all initial cases.
- Reduced ADC values were observed in 45 out of 59 lesions compared to normal parenchyma.
- EPDI identified abnormalities not seen or more subtle on conventional MRI in several cases.
- Follow-up studies indicated resolution of EPDI signal abnormalities or progression of changes.
Conclusions:
- EPDI is a rapid and sensitive MRI technique for detecting pediatric watershed ischemic/infarction.
- EPDI can identify these changes earlier than conventional MRI, aiding in prompt diagnosis.
- The technique is valuable for evaluating children with hypoperfusion episodes and suspected brain injury.
Abstract:
The purpose of our study was to determine the usefulness of echo-planar diffusion-weighted imaging (EPDI) in the evaluation of watershed hypoxic-ischemic brain injury in pediatric patients. Eighteen patients ranging in age from 3 weeks to 12 years were evaluated for evidence of ischemic/infarction changes on conventional MR and EPDI. Included in the study group were five patients with sickle cell disease, four with congenital heart disease, four with hypotensive episodes with various etiologies, three with sepsis, and two with encephalitis or meningitis. Patients were examined 2 h to 6 days after the initial insult, with follow-up studies in four patients at 1 to 62 days after the initial examination. After conventional MR imaging (T1, FSE T2, and FLAIR), diffusion-weighted MR imaging was performed using high-speed, single-shot EP techniques with TR 6000, TE 144, matrix 96 x 128, FOV 23.3 x 31 and five b values of 0, 160, 360, 640, and 1,000 s/mm2. EPDI demonstrated abnormally increased signal in watershed ischemic/infarction zones in all initial cases. Apparent diffusion coefficients (ADC) were obtained in 59 lesions. When compared with radiographically normal (on EPDI) contralateral brain parenchyma, 45 demonstrated a relatively decreased ADC, while eight had normal ( +/- 10%) and six had increased ADC. In four cases, signal abnormalities on EPDI were not seen or exceeded that seen with conventional MR imaging. In the remaining cases, signal abnormalities were obvious on EPDI and more subtle on conventional MR imaging. Follow-up studies demonstrated resolution of abnormal EPDI signal with persistent abnormalities on conventional imaging in some cases, while others revealed an increase in size or number of EPDI signal abnormalities, suggesting ongoing acute ischemic/infarctive changes. EPDI is a rapid, sensitive technique for detecting watershed ischemic/infarction changes in pediatric patients with hypoperfusion episodes, at times before such changes are apparent on conventional MR images and/or are clinically apparent.
