Diffusion-weighted magnetic resonance imaging [Neurosurgery Wiki]

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====== Diffusion-weighted magnetic resonance imaging ======

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[[Diffusion]]-weighted [[magnetic resonance imaging]] ([[DWI]] or DW-MRI) is the use of specific [[MRI]] sequences as well as [[software]] that generates images from the resulting [[data]], that uses the [[diffusion]] of [[water molecule]]s to generate contrast in [[MR]] images.

It allows the mapping of the diffusion process of molecules, mainly water, in biological tissues, in vivo and non-invasively. Molecular diffusion in tissues is not free but reflects interactions with many obstacles, such as macromolecules, fibers, and membranes. Water molecule diffusion patterns can therefore reveal microscopic details about tissue architecture, either normal or in a diseased state. A special kind of DWI, diffusion tensor imaging (DTI), has been used extensively to map white matter [[tractography]] in the brain.

DWI exploits the random motion of water molecules. The extent of tissue cellularity and the presence of intact cell membrane help determine the impedance of water molecule diffusion. This impedance of water molecules diffusion can be quantitatively assessed using the [[apparent diffusion coefficient]] (ADC) value.

===== Indications =====

[[Diffusion-weighted magnetic resonance imaging indications]].



====Hyperintense lesions====
Hyperintense lesions around the resection cavity on [[magnetic resonance]] diffusion-weighted imaging (MR-DWI) frequently appear after brain tumor surgery due to the damage of surrounding brain. The putative connection between the lesion and the prognosis for patients with glioblastoma (Glioblastoma) was explored in sixty-one patients with newly diagnosed Glioblastoma. Postoperative MRI was performed within 2 weeks after the initial surgery.

The cases into two groups depending on whether DWI hyperintense lesions were observed or not [DWI(+) group and DWI(-) group]. Progression-free survival (PFS) and overall survival (OS) were compared between the two groups. Forty-two patients were identified. The various extents of hyperintense lesions around the resection cavity were observed in 28/42 (66.7 %) cases. In the DWI(+) and DWI(-) groups, median PFS was 10.0 [95 % confidence interval (CI) 8.4-11.5] and 6.7 (95 % CI 4.9-8.5) months, respectively (p = 0.042), and median OS was 18.0 (95 % CI 12.2-23.8) and 17.0 (95 % CI 15.7-18.3) months, respectively (p = 0.254). On multivariate analysis, the presence of DWI hyperintense lesion was more likely to be an independent predictor for 6-month PFS (p = 0.019; HR, 0.038; 95 % CI 0.002-0.582). Tumor recurrence appeared outside the former DWI hyperintense lesion. Hyperintense lesions surrounding the resected Glioblastoma on MR-DWI might be a favorable prognostic factor in patients with Glioblastoma
((Furuta T, Nakada M, Ueda F, Watanabe T, Arakawa Y, Higashi R, Hashimoto M,
Nitta H, Hayashi Y, Hamada JI. Prognostic paradox: brain damage around the
glioblastoma resection cavity. J Neurooncol. 2014 Mar 7. [Epub ahead of print]
PubMed PMID: 24604751.)).

===== Diffusion-weighted imaging in stimulated echo acquisition mode =====
[[Diffusion-weighted imaging in stimulated echo acquisition mode]].

===== Diffusion-weighted magnetic resonance imaging for acute ischemic stroke diagnosis =====
[[Diffusion-weighted magnetic resonance imaging for acute ischemic stroke diagnosis]].