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Clinical single-shot diffusion-weighted MRI of the human brain on a short-bore medium-field imager
K O Lövblad1, L Remonda, O Heid
1Department of Neuroradiology, University of Bern, Inselspital, Switzerland. loevk@insel.ch
Abstract:
Diffusion-weighted MRI (DWI) is becoming important for assessment of acute stroke. Until recently single-shot DWI required expensive technology such as echoplanar imaging (EPI) available only at some research sites. A new medium-field (1.0 T) short-bore MR imager has been developed with which DWI data sets can be acquired. We prospectively studied 169 patients on this 1.0 T commercial system. After conventional imaging, DWI was performed with a single-shot multi-slice sequence with b values 0 an 900 s/mm2, and with the gradients switched in three directions. The apparent diffusion coefficients were calculated with online calculation software. There were 50 patients with totally normal MRI, and 17 had strokes, these strokes were detected as areas of high signal on the images at a maximal b value. There was a drop in the ADC in ischaemic regions: in sub-acute infarcts, the values were between 0.41 and 0.531 x 10(-3) mm2/s. In old infarcts the ADC was 1.15 x 10(-3) mm2/s. Cerebrospinal fluid (CSF) gave low signal whereas areas in the brain had more intermediate intensities (CSF: 3.00; deep white matter: 0.75, cortical grey matter: 0.80, basal ganglia (thalamus): 0.70 and cerebellar white matter: 0.65 x 10(-3) mm2/s. Anisotropy was detected as areas of restricted diffusion along the tracts. These preliminary data show that DWI can be acquired successfully on a medium-field short-bore system. This should allow the technique to be implemented at more sites, therefore facilitating the diagnosis of acute stroke and rendering early intervention feasible.
Insights
Diffusion-weighted MRI (DWI) on a new medium-field system successfully detects acute stroke. This advancement makes DWI more accessible, aiding earlier stroke diagnosis and intervention.
Area of Science:
- Radiology
- Neurology
- Medical Imaging
Background:
- Diffusion-weighted MRI (DWI) is crucial for acute stroke assessment.
- Conventional single-shot DWI often requires expensive echoplanar imaging (EPI) technology.
- Limited availability of EPI restricts DWI implementation at many clinical sites.
Purpose of the Study:
- To evaluate the feasibility of acquiring DWI data on a new commercial medium-field (1.0 T) short-bore MR imager.
- To assess the utility of this system for detecting acute stroke.
- To determine if this system can broaden access to DWI for stroke diagnosis.
Main Methods:
- Prospective study of 169 patients using a 1.0 T short-bore MR system.
- Acquisition of DWI datasets using a single-shot multi-slice sequence (b values 0 and 900 s/mm²).
- Calculation of apparent diffusion coefficients (ADC) with online software; analysis of signal intensities and anisotropy.
Main Results:
- DWI successfully detected 17 strokes as areas of high signal.
- A significant drop in ADC was observed in ischemic regions (sub-acute: 0.41-0.531 x 10⁻³ mm²/s; old: 1.15 x 10⁻³ mm²/s).
- Distinct signal intensities were measured for cerebrospinal fluid and various brain tissues, with anisotropy noted along white matter tracts.
Conclusions:
- Diffusion-weighted imaging (DWI) can be successfully acquired on a medium-field, short-bore MR system.
- This system facilitates DWI implementation at more clinical sites.
- Wider accessibility of DWI can improve acute stroke diagnosis and enable timely intervention.