What does diffusion weighted imaging measure?
Diffusion weighted imaging (DWI) is based on measuring the Brownian motion of water molecules, which is restricted in highly cellular tissue such as tumor tissue compared with water motion in normal and low cellular benign tissue.
How is diffusion weighted imaging done?
This is done by applying a strong gradient symmetrically on either side of the 180-degree pulse. The degree of diffusion weighting is dependent primarily on the area under the diffusion gradients (which is in turn related to the amplitude and duration of the gradient) and on the interval between the gradients.
What is the best imaging for prostate?
MRI/MRSI. MRI has been extensively studied for its ability to detect prostate cancers. The use of endorectal coil MRI allows better visualization of prostate zonal anatomy and location and extent of tumor within the gland.
What does restricted diffusion mean on prostate MRI?
Prostate cancer results in increased cellularity, and a reduction of the extracellular space, and results in restricted diffusion on DWI. The strength and duration of the diffusion gradient detected are referred to as “b-values” with higher values resulting in the production of a higher signal intensity (Figure 4A).
How long does diffusion last?
How long does diffusion last? Until it reaches equilibrium, when there is an equal amount of the substance distributed everywhere.
Is an MRI of the prostate better than a biopsy?
Among the diagnostic strategies considered, the MRI pathway has the most favourable diagnostic accuracy in clinically significant prostate cancer detection. Compared to systematic biopsy, it increases the number of significant cancer detected while reducing the number of insignificant cancer diagnosed.
What size prostate lesions are cancerous?
Conclusions: These data indicate that clinically significant prostate cancer in lesions less than 0.65 cm and greater than 1.70 cm may be characterized with a single targeted biopsy core, sparing 33.5% of lesions (21% patients) a double core targeted biopsy.
What is a common cause of diffusion abnormality?
The vast majority of restricted-diffusion abnormalities result from acute stroke, and as such, the diagnosis may be problematic when this MRI feature results from other causes. Distinct patterns of restricted diffusion seen with various disease conditions can play an important diagnostic role.
Can diffusion-weighted imaging of the prostate improve sensitivity to prostate cancer?
High-resolution diffusion-weighted imaging of the prostate We showed that for DWI of the prostate at 3-7 mm(3) voxel sizes the benefits of higher spatial resolution outweigh the effects of reduced signal-to-noise and contrast-to-noise ratios, potentially improving the sensitivity to small or sparse prostate cancers.
What is diffusion-weighted imaging?
Diffusion-Weighted Imaging of the Prostate Technical Aspects Conventional MRI is based on the 1H signal from water (1H2O). Water molecules of the body have constant random brownian motion, a property that is explored by DWI.
What is the b value in diffusion weighted imaging?
Diffusion-Weighted Imaging of the Prostate. The strength of these gradient pulses, in part determined by the gradient’s amplitude, is reflected by the b value of the DWI sequence. Use of stronger gradient pulses (indicated by a greater b value) increases the sensitivity of the DWI sequence to water motion.
Which MRI techniques are used in multiparametric MRI of the prostate?
In multiparametric MRI of the prostate, at least two functional MRI techniques, such as diffusion-weighted MRI (DW-MRI) and dynamic contrast-enhanced MRI, are combined with conventio … Diffusion-weighted MRI and its role in prostate cancer