The added value of intravoxel incoherent motion diffusion weighted imaging parameters in differentiating high-grade pancreatic neuroendocrine neoplasms from pancreatic ductal adenocarcinoma.
The aim of the present study was to investigate the potential significance of intravoxel incoherent motion (IVIM)-diffusion weighted imaging (DWI) in differentiating high-grade pancreatic neuroendocrine neoplasms (pNENs) from pancreatic ductal adenocarcinoma (PDAC). A total of 50 patients, including 37 patients with PDAC and 13 patients with high-grade pNENs, underwent pancreatic multiple b-values DWI with 15 b-values including 0, 10, 20, 40, 60, 80, 100, 150, 200, 400, 800, 1,000, 1,200, 1,500 and 2,000 sec/mm2. Standard apparent diffusion coefficient (ADCstandard) and IVIM parameter [slow apparent diffusion coefficient (Dslow), fast apparent diffusion coefficient (Dfast), fraction of fast apparent diffusion coefficient (ƒ)] values of PDAC and pNENs were compared. P<0.05 was considered to indicate a statistically significant difference. Receiver operating characteristics analysis was performed in order to evaluate the diagnostic potential of IVIM parameters for differentiating high-grade pNENs from PDAC. Dslow of pNENs was significantly lower compared with that of PDAC (0.460 vs. 0.579×10-3 mm2/sec; P=0.001). Dfast of pNENs was significantly higher compared with that of PDAC (13.361 vs. 4.985×10-3 mm2/sec; P<0.001). Area under the curve of Dslow, Dfast and combined Dslow and Dfast was 0.793, 0.863 and 0.885 respectively. The specificity and sensitivity of Dslow≤0.472×10-3 mm2/sec were 97.3 and 53.9%, respectively, for differentiating high-grade pNENs from PDAC. The specificity and sensitivity of Dfast >9.58×10-3 mm2/sec were 91.9 and 69.2%, respectively, for differentiating high-grade pNENs from PDAC. When Dslow and Dfast were combined, the specificity and sensitivity for differentiating high-grade pNENs from PDAC were 76.9 and 100%, respectively. Taken together, these results indicated that the diffusion-associated parameter Dslow and the perfusion-associated parameter Dfast of IVIM-DWI may differentiate high-grade pNENs from PDAC with high diagnostic accuracy, and that IVIM-DWI may be a valuable biomarker in differentiating pancreatic neoplasms.
Ma W
，Wei M
，Han Z
，Tang Y
，Pan Q
，Zhang G
，Ren J
，Huan Y
，Li N
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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
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Can diffusion-weighted imaging serve as a biomarker of fibrosis in pancreatic adenocarcinoma?
To assess the relationship between diffusion-weighted imaging (DWI) and intravoxel incoherent motion (IVIM)-derived quantitative parameters (apparent diffusion coefficient [ADC], perfusion fraction [f], Dslow , diffusion coefficient [D], and Dfast , pseudodiffusion coefficient [D*]) and histopathology in pancreatic adenocarcinoma (PAC).
Subjects with suspected surgically resectable PAC were prospectively enrolled in this Health Insurance Portability and Accountability Act (HIPAA)-compliant, Institutional Review Board-approved study. Imaging was performed at 1.5T with a respiratory-triggered echo planar DWI sequence using 10 b values. Two readers drew regions of interest (ROIs) over the tumor and adjacent nontumoral tissue. Monoexponential and biexponential fits were used to derive ADC2b , ADCall , f, D, and D*, which were compared to quantitative histopathology of fibrosis, mean vascular density, and cellularity. Two biexponential IVIM models were investigated and compared: 1) nonlinear least-square fitting based on the Levenberg-Marquardt algorithm, and 2) linear fit using a fixed D* (20 mm2 /s). Statistical analysis included Student's t-test, Pearson correlation (P < 0.05 was considered significant), intraclass correlation, and coefficients of variance.
Twenty subjects with PAC were included in the final cohort. Negative correlation between D and fibrosis (Reader 2: r = -0.57 P = 0.01; pooled P = -0.46, P = 0.04) was observed with a trend toward positive correlation between f and fibrosis (r = 0.44, P = 0.05). ADC2b was significantly lower in PAC with dense fibrosis than with loose fibrosis ADC2b (P = 0.03). Inter- and intrareader agreement was excellent for ADC, D, and f.
In PAC, D negatively correlates with fibrosis, with a trend toward positive correlation with f suggesting both perfusion and diffusion effects contribute to stromal desmoplasia. ADC2b is significantly lower in tumors with dense fibrosis and may serve as a biomarker of fibrosis architecture.
1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:393-402.
Hecht EM
，Liu MZ
，Prince MR
，Jambawalikar S
，Remotti HE
，Weisberg SW
，Garmon D
，Lopez-Pintado S
，Woo Y
，Kluger MD
，Chabot JA
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