![]() ĭiffusion-weighted imaging of the breast is technically challenging because of the breast being off center within the bore and having intrinsic susceptibility artifacts. The diagnostic advantage of such a method for the breast is unclear. As the first b value, it is also possible to select a b value ( b ≥ 50 s/mm 2) other than zero to avoid perfusion and flow effects. However, the breast studies on the use of b values more than two have not been shown superiority, therefore two- b value DW-MRI is still used as the standard. Performing DW-MRI with more than two b values provides a more accurate sampling of the signal drop. With the aim of benign and malignant discrimination, selection of b value is less critical. For lesion detection, high b values (800–1500 s/mm 2) are preferred to create a respectable distinction between the lesion and the neighboring soft tissues. Certain b values should be used to standardize ADC thresholds. ![]() The b value provides data on the level of the diffusion weighting and is proportional to the gradient strength and diffusion time. It is recommended to choose the same plane as used for DCE imaging for synchronized evaluation (Fig. This set of data is known as the ADC map. T2-effects can be mathematically removed from DW-MRI to create a pure parametric image. On DW-MRI with an increasing b value, T2 effects will decrease (Fig. The best-known example of this problem is the T2 shine through effect. On the other hand, saw contrast on DW-MRI is determined by not only diffusion features but also relaxation times and proton concentration. This feature is mostly associated with high cell density and limited extracellular planetary. Diffusion restriction is appreciated as bright signal intensity (SI) on DW-MRI and having decreased apparent diffusion coefficient (ADC) values. In general, on DW-MRI, malignant lesions show diffusion restriction. However, it has not yet been included in BI-RADS lexicon. It has shown to be potential to increase the accuracy for the lesion characterization on DCE-MRI with multiple studies. In this clinical setting, breast DW-MRI has been reported to diminish false-positive consequences, excessive interventions, and improve the positive predictive value. Because imaging characteristics demonstrate some overlap for benign and malignant tumors and wide deviations of the positive predictive value (24–89%) have been reported. Although it allows high sensitivity (approaching 100%), it just delivers a moderate specificity (21–100%) for breast cancer detection. DCE-MRI provides great anatomic-morphologic detail and kinetic information about the lesions. The common clinical indications for dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) are screening of women at high-risk, assessment of the extent of disease for cancer, evaluation of unclear findings on conventional methods or physical examination, and the estimation of the response to neoadjuvant chemotherapy. ![]() This is the quantification of DW-MRI and means the diffusion in biologic tissues is actually not unrestricted and is controlled by complex appliances.ĭW-MRI is nearly always integrated into dynamic contrast-enhanced (DCE)-MRI protocols. ![]() Apparent diffusion coefficient (ADC) is the typical extent a water molecule of a concerned tissue occupies as square mm per second. So DW-MRI settles down its own tissue contrast without the need for contrast injection. b value is the real diffusion weighting or sensitization (s/mm 2). During the acquisition, motion-sensitizing gradients are used. Diffusion-weighted magnetic resonance imaging (DW- MRI) is a non-contrast procedure, measuring the motion of water particles in vivo and analyzing microscopic tissue structure: cellularity, membrane integrity, viscosity, fibers, tubules, organelles, and macromolecules.
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