The intravoxel incoherent motion (IVIM) imaging is an advanced diffusion-weighted imaging (DWI) technique that allows for a separate quantitative evaluation of all the microscopic random motions that contribute to DWI, which are essentially represented by molecular diffusion and blood microcirculation (perfusion)¹⁾. Single-shot echo-planar (EP)-DWI is most commonly used for IVIM imaging. However, EP-DWI is associated with strong susceptibility artifacts that cause image distortions in the skull base, making it difficult, if not impossible to measure the IVIM parameters in the anterior pituitary lobe accurately. Turbo spin-echo (TSE)-DWI was reported to mitigate such problems in the skull base and sinonasal cavities ²⁾. The purpose of this study was to evaluate the feasibility of IVIM assessment based on TSE-DWI in the normal anterior pituitary lobe.First, we performed an in-vitro experiment for validation of TSE-DWI sequence on a GDTPA-doped water phantom by comparing the signal decay according to b values between EP-DWI and TSE-DWI using the concordance correlation coefficient (CCC). The imaging conditions were as follows: 3T MR imager and a 15-channel receiver head coil; TR/TE 3,000/52 ms; flip angle 90°; 3 MPG directions; FOV 180 mm; imaging matrix 100 x 100; number of excitations 6. We used13 different b values (0, 10, 20, 30, 50, 80, 100, 200, 300, 400, 600, 800, and 1,000 s/mm²). A 3 mm-thick sagittal slice was placed. Second, in-vivo validation study for IVIM based on TSE-DWI was conducted using 5 healthy volunteers. For the TSE-DWI sequence, peripheral pulse triggering was utilized to reduce signal variability due to CSF pulsation (resultant TR 2,400-3,000 ms). For each subject, an additional IVIM imaging based on conventional EP-DWI was performed for comparison. The true diffusion coefficient (D), perfusion fraction (f), and pseudo-diffusion coefficient (D*) were calculated by fitting the IVIM model to the measured signal changes for each voxel. Agreement of D, f, and D* measured with the 2 methods in 4 regions-of-interests (ROIs) in the brain white matter (WM) regions (pons, vermis, and genu and splenium of the corpus callosum) was assessed using the Bland-Altman plot. Finally, the three IVIM parameters (D, f, and D*) in the anterior pituitary lobe were compared with those in the 4 ROIs in the WM using Dunnett's test in 7 healthy volunteers.The phantom experiment revealed complete accordance in the signal decay between EP-DWI and TSE-DWI (CCC>0.9999). In all subjects, TSE-DWI visualized the pituitary gland with acceptable image distortion (Fig. 1). The Bland-Altman analysis showed that the agreement between TSE-DWI and EP-DWI was good (95% limits of agreement ranged from -0.1086 to 0.0786 x10^-3 mm²/s) for D, fair (-5.03 to 4.32 %) for f, and poor (-8.41 to 5.79 x10^-3 mm²/s) for D* (Fig. 2). No obvious systematic bias was shown for any parameter. The mean D (x10^-3 mm²/s) in the normal anterior pituitary lobe was 0.960±0.097, which was significantly higher than those in the pons (0.711±0.024), vermis (0.666±0.027), and genu (0.699±0.042) and splenium (0.749±0.038) of the corpus callosum (P < .001, respectively. Fig. 3A). The f (%) in the normal anterior pituitary lobe was 13.15±2.37, which was significantly higher than those in the pons (5.56±1.45), vermis (3.94±1.36), and genu (5.32±1.24) and splenium (5.15±1.00) of the corpus callosum (P < .001, respectively. Fig. 3B). The D* (5.81±2.15 x10^-3 mm²/s) in the normal anterior pituitary lobe was not significantly different from those in the pons (5.96±2.75), vermis (3.75±3.02), and genu (7.72±1.32) and splenium (5.35±2.39) (Fig. 3C), which may be due to high variability.Our results for the agreement showed that IVIM assessment based on TSE-DWI can provide similar information regarding D and f, but not D* to that provided by conventional EP-DWI. Moreover, the values of D and f in the brain WM measured with TSE-DWI were in good agreement with previously published values obtained with EP-DWI ³⁾ .The normal anterior pituitary lobe was shown to have higher f than the brain WM, which is consistent with high histological microvascular density in the anterior pituitary lobe ⁴⁾. Taken together, our study suggests that IVIM assessment based on TSE-DWI in the normal anterior pituitary lobe is feasible. It may be useful to characterize pituitary lesions such as microadenoma.