Whole-body intravoxel incoherent motion imaging.

OBJECTIVES

To investigate the technical feasibility of whole-body intravoxel incoherent motion (IVIM) imaging.

MATERIALS AND METHODS

Whole-body MR images of eight healthy volunteers were acquired at 3T using a spin-echo echo-planar imaging sequence with eight b-values. Coronal parametrical whole-body maps of diffusion (D), pseudodiffusion (D*), and the perfusion fraction (Fp) were calculated. Image quality was rated qualitatively by two independent radiologists, and inter-reader reliability was tested with intra-class correlation coefficients (ICCs). Region of interest (ROI) analysis was performed in the brain, liver, kidney, and erector spinae muscle.

RESULTS

Depiction of anatomic structures was rated as good on D maps and good to fair on D* and Fp maps. Exemplary mean D (10(-3) mm(2)/s), D* (10(-3) mm(2)/s) and Fp (%) values (± standard deviation) of the renal cortex were as follows: 1.7 ± 0.2; 15.6 ± 6.5; 20.9 ± 4.4. Inter-observer agreement was "substantial" to "almost perfect" (ICC = 0.80 - 0.92). The coefficient of variation of D* was significantly lower with the proposed algorithm compared to the conventional algorithm (p < 0.001), indicating higher stability.

CONCLUSION

The proposed IVIM protocol allows computation of parametrical maps with good to fair image quality. Potential future clinical applications may include characterization of widespread disease such as metastatic tumours or inflammatory myopathies.

KEY POINTS

• IVIM imaging allows estimation of tissue perfusion based on diffusion-weighted MRI. • In this study, a clinically suitable whole-body IVIM algorithm is presented. • Coronal parametrical whole-body maps showed good depiction of anatomic details. • Potential future applications include detection of widespread metastatic or inflammatory disease.