Whole body MRI: improved lesion detection and characterization with diffusion weighted techniques.
Bottom Line: Theory, b-value selection, common artifacts and target to background for optimized viewing will be reviewed for applications in the neck, chest, abdomen, and pelvis.DWI, when used in conjunction with routine imaging, can assist in detecting hemorrhagic degradation products, infection/abscess, and inflammation in colitis, while aiding with discrimination of free fluid and empyema, while limiting the need for intravenous contrast.DWI in conjunction with routine anatomic images provides a platform to improve lesion detection and characterization with findings rivaling other combined anatomic and functional imaging techniques, with the added benefit of no ionizing radiation.
Affiliation: AIM Medical Imaging, Vancouver, BC, Canada. email@example.comShow MeSH
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Mentions: Clinical diffusion-weighted images are T2-weighted; thus, the native tissue being interrogated can elicit T2 shine through effects. Thus, to separate restricted diffusion tissue from T2 shine through effects, methods analogous to those applied to the brain can be used, namely comparison with standard T2 sequences, and with ADC maps/values. Normal tissue, which demonstrates restricted diffusion due to anisotropy, or tissue density include brain and spinal cord, spleen, lymph nodes, red marrow, ovaries, testes, and endometrium. Restricted tissue based on T2 shine through include normal gallbladder, salivary glands, prostate, and hemangiomas 30. Early hematomas in the body demonstrate similar findings to those shown in intracranial hemorrhages and appear restricted on DWI imaging because of both paramagnetic effects and restricted diffusion 31; thus, the importance of comparison with conventional sequences for appropriate tissue assessment is demonstrated in an example of an endometrioma (Fig. 10).
Affiliation: AIM Medical Imaging, Vancouver, BC, Canada. firstname.lastname@example.org