Intravoxel incoherent motion diffusion-weighted imaging for characterizing focal hepatic lesions: Correlation with lesion enhancement.

To evaluate the value of intravoxel incoherent motion (IVIM) parameters for characterizing focal hepatic lesions, and to assess the correlation between IVIM parameters and arterial nodule enhancement. We retrospectively evaluated 161 lesions (91 hepatocellular carcinomas [HCCs], 27 intrahepatic cholangiocarcinomas [IHCCs], 20 hemangiomas, 9 combined hepatocellular-cholangiocarcinomas, 9 metastases, and 5 other tumors) in 161 patients (105 men and 56 women; mean age, 56.4 years). Diffusion-weighted imaging was performed using nine b-values (0-900 s/mm2 ) at 1.5T. Apparent diffusion coefficient (ADC), molecular diffusion coefficient (Dslow ), perfusion fraction (f), and perfusion-related diffusion coefficient (Dfast ) were compared among the hepatic lesions using analysis of variance (ANOVA). Receiver-operating-characteristic analysis was performed to assess diagnostic performance. The enhancement fraction (EF) and the relative enhancement (RE) of the hepatic lesions on arterial phase gadoxetic acid-enhanced images were correlated with the IVIM parameters using Spearman's test. For the differentiation of hemangiomas from malignant tumors, Dslow showed the largest area under the curve (0.933) among all parameters. Although ADC did not show any difference among malignant lesions (P ≥ 0.28), HCCs showed a significantly lower Dslow than IHCC (P < 0.001) and a higher f than did IHCC (P < 0.001) and metastasis (P = 0.027); f had a significant positive correlation with EF (r = 0.420, P < 0.001) and RE (r = 0.264, P = 0.001). IVIM parameters are more helpful in characterizing malignant hepatic lesions than ADC; f may reflect the extent and degree of hepatic nodule enhancement in the arterial phase, and may allow for differentiation of HCC from IHCC and metastasis. 3 J. MAGN. RESON. IMAGING 2017;45:1589-1598.

Choi IY ，Lee SS ，Sung YS ，Cheong H ，Lee H ，Byun JH ，Kim SY ，Lee SJ ，Shin YM ，Lee MG ... -  《-》

Determination of malignancy and characterization of hepatic tumor type with diffusion-weighted magnetic resonance imaging: comparison of apparent diffusion coefficient and intravoxel incoherent motion-derived measurements.

Doblas S ，Wagner M ，Leitao HS ，Daire JL ，Sinkus R ，Vilgrain V ，Van Beers BE ... -  《-》

Intravoxel incoherent motion diffusion-weighted imaging of the pancreas: Characterization of benign and malignant pancreatic pathologies.

To evaluate the diagnostic value of apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) parameters in differentiating patients with either a normal pancreas (NP), pancreatic ductal adenocarcinoma (PDAC), neuroendocrine tumor (NET), solid pseudopapillary tumor (SPT), acute pancreatitis (AcP), vs. autoimmune pancreatitis (AIP). In all, 84 pathologically confirmed pancreatic tumors (60 PDACs, 15 NETs, 9 SPTs), 20 pancreatitis (13 AcPs, 7 AIPs), and 30 NP subjects underwent IVIM diffusion-weighted imaging using 10 b-values (0-900 sec/mm2 ) at 1.5T. The ADC, pure molecular diffusion coefficient (Dslow ), perfusion fraction (f), and perfusion-related diffusion coefficient (Dfast ) were calculated and compared using a Kruskal-Wallis test and post-hoc Dunn procedure. Receiver operating characteristic (ROC) analysis was performed to assess diagnostic performance. The f and Dfast of the PDAC were significantly lower than that of the NP (f = 0.10 vs. 0.24; Dfast  = 42.21 vs. 71.74 × 10-3 mm2 /sec; P < 0.05). In ROC analysis, f showed the best diagnostic performance (area-under-the-curve, 0.919) among all parameters in differentiating PDAC from NP (P ≤ 0.001). The f values of AcP (0.11) and AIP (0.13) and the Dfast values of SPT (20.48 × 10-3 mm2 /sec) and AcP (24.49 × 10-3 mm2 /sec) were significantly lower compared with NP (f = 0.24; Dfast  = 71.74 × 10-3 mm2 /sec; P < 0.05). For NET, the f (0.21) was significantly higher than that of PDAC (0.10, P < 0.01). Perfusion-related parameters f and Dfast are more helpful in characterizing pancreatic diseases than ADC or Dslow . The PDCA, SPT, AcP, and AIP were characterized by reduced f and Dfast values compared with normal pancreas. The f value might help in differentiating between PDAC and NET. 3 J. Magn. Reson. Imaging 2017;45:260-269.

Kim B ，Lee SS ，Sung YS ，Cheong H ，Byun JH ，Kim HJ ，Kim JH ... -  《-》

Intravoxel incoherent motion diffusion-weighted MRI of the abdomen: The effect of fitting algorithms on the accuracy and reliability of the parameters.

To evaluate the influence of fitting methods on the accuracy and reliability of intravoxel incoherent motion (IVIM) parameters, with a particular emphasis on the constraint function. Diffusion-weighted (DW) imaging data were analyzed using IVIM-based full-fitting (simultaneous fit of all parameters) and segmented-fitting (step-by-step fit of each parameter), each with and without the constraint function, to estimate the molecular diffusion coefficient (Dslow ), perfusion fraction (f), and flow-related diffusion coefficient (Dfast ). Computational simulations were performed at variable signal-to-noise ratios to evaluate the relative error (RE) and coefficient of variation (CV) of the estimated IVIM parameters. DW imaging of the abdomen was performed twice at 1.5 Tesla using nine b-values (0-900 s/mm2 ) in 12 health volunteers (6 men and 6 women; mean age: 30 years). The measurement repeatability of IVIM parameters in the liver and the pancreas was evaluated using the within-subject coefficient of variation (w CV). In simulations, full-fitting without the constraint function yielded the largest RE (P < 0.001 for Dslow and f; P ≤ 0.044 for Dfast ) and CV (P ≤ 0.033 for Dslow and f; P ≤ 0.473 for Dfast ) for IVIM parameters among all four algorithms. In volunteer imaging, full-fitting without the constraint function also resulted in the poorest repeatability for Dslow (w CV, 17.12%-65.45%) and f (w CV, 19.35%-42.84%) in the liver and pancreas, while the other algorithms had similar repeatability values (w CV, 4.05%-11.99% for Dslow and 9.65%-18.66% for f). Measurement repeatability of Dfast (w CV, 29.52%-85.01%) was the poorest among the IVIM parameters. For accurate and reliable measurement of IVIM parameters, segmented fitting or full-fitting with the constraint function should be used for IVIM-based analysis of DW imaging. 3 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;45:1637-1647.

Park HJ ，Sung YS ，Lee SS ，Lee Y ，Cheong H ，Kim YJ ，Lee MG ... -  《-》

[Value of intravoxel incoherent motion diffusion-weighted imaging in differential diagnosis of benign and malignant hepatic lesions and blood perfusion evaluation].

Ying ML ，Xiao WW ，Xu SL ，Shu JE ，Pan JF ，Fu JF ，Lu JH ，Pan YH ，Jiang Y ... -  《-》