For many years DW imaging of the body under free breathing conditions was considered impossible because it was thought that cardiac and respiratory motion would lead to irretrievable loss of diffusion-weighted information. In 2004 Takahara et al. overcame these limitations, developing a technique they named diffusion-weighted whole-body imaging with background body signal suppression (DWIBS).
The conceptual break-through that made DWIBS feasible was the recognition that even though organs of the abdomen and chest move during image acquisition, they do so "coherently". Their physical displacements are cyclic and while this motion produces some spatial blurring it does not significantly affect the magnitude of the DW signal.
As currently implemented, DWIBS is more reliably performed at 1.5T because of increased susceptibility artifacts at 3.0T. Moderately strong diffusion-sensitizing gradients are used (b-values on the order of 1000 s/mm²), preceded by a plus a STIR-like inversion pulse for fat suppression. Blocks of approximately 60 axial images 4-5-mm-thick are acquired using parallel imaging and echo-planar readout, with imaging times in the range of 7 min per station. Depending on patient size a "whole-body" DWIBS survey from the neck through the pelvis can be acquired in 45 minutes or less. The blocks are digitally stitched together and displayed in an inverted mode that resembles PET-CT. Lymphoma, prostate cancer, and small cell carcinoma have been the most widely studied. Because of artifacts, conventional MR images must still be obtained for confirmation of DWIBS lesions.
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The interpretive problems surrounding DWIBS, however, are not trivial. Many indeterminate and questionable lesions are identified that must be resolved by other conventional methods. The technique only works for a few cancers (like lymphoma and small-cell tumors) that significantly restrict diffusion. We will just have to wait and see whether DWIBS survives the test of time.
Godinho MV, de Oliveira RV, Canella C, et al. Initial experience with whole-body diffusion-weighted imaging in oncological and non-oncological patients. MAGNETOM Flash 2013; 2:94-102.
Kwee TC. New techniques for staging malignant lymphoma. Utrecht, 2011, pp. 67-111.
Takahara T, Imai Y, Yamashita T, et al. Diffusion weighted whole body imaging with background body signal suppression (DWIBS): technical improvement using freet using free breathing, STIR and high resolution 3D display. Radiat Med 2004;22:275-282