Jin Young Jang

Intravoxel incoherent motion diffusion-weighted imaging of pancreatic neuroendocrine tumors: prediction of the histologic grade using pure diffusion coefficient and tumor size.

PurposeThe purpose of this study was to assess the value of intravoxel incoherent motion and diffusion-weighted imaging for predicting the histologic grade of pancreatic neuroendocrine tumors (PNETs). Materials and MethodsForty patients with surgically diagnosed PNETs who underwent preoperative magnetic resonance imaging, including diffusion-weighted imaging with a series of 10 b values (0–1000 s/mm2), were included in this institutional review board–approved retrospective study. The apparent diffusion coefficient (ADCtotal), the intravoxel incoherent motion parameters (pure diffusion coefficient [D], pseudodiffusion coefficient [D*], and perfusion fraction [f]) were measured on the tumors. Histologic grading was performed on the basis of the World Health Organization 2010 classification system. Logistic regression analysis and receiver operating curve analysis were performed to identify the significant factors predicting the histologic grades. ResultsGrades 2 and 3 tumors were significantly larger than grade 1 tumors (average 3.62 cm vs 2.17 cm in diameter; P = 0.001). Grades 2 and 3 tumors showed significantly lower D values than did grade 1 tumors (0.95 vs 1.21 × 10−3 mm2/s; P = 0.009), although the ADCtotal showed no significant difference. When any of the following 2 criteria was used, (a) tumor size smaller than 2.0 cm in diameter and (b) D value greater than 1.2 × 10−3 mm2/s, the sensitivity, specificity, and positive predictive value for diagnosing grade 1 PNETs were 76.92%, 100%, and 100%, respectively. ConclusionsPure diffusion coefficient (D) is possibly a better marker than ADCtotal is for differentiating grade 1 from grade 2 or 3 PNET and, combined with tumor size, can predict grade 1 PNET with a high specificity.

Reduced Field-of-View Diffusion-Weighted Magnetic Resonance Imaging of the Pancreas: Comparison with Conventional Single-Shot Echo-Planar Imaging.

Objective To investigate the image quality (IQ) and apparent diffusion coefficient (ADC) of reduced field-of-view (FOV) di-ffusion-weighted imaging (DWI) of pancreas in comparison with full FOV DWI. Materials and Methods In this retrospective study, 2 readers independently performed qualitative analysis of full FOV DWI (FOV, 38 × 38 cm; b-value, 0 and 500 s/mm2) and reduced FOV DWI (FOV, 28 × 8.5 cm; b-value, 0 and 400 s/mm2). Both procedures were conducted with a two-dimensional spatially selective radiofrequency excitation pulse, in 102 patients with benign or malignant pancreatic diseases (mean size, 27.5 ± 14.4 mm). The study parameters included 1) anatomic structure visualization, 2) lesion conspicuity, 3) artifacts, 4) IQ score, and 5) subjective clinical utility for confirming or excluding initially considered differential diagnosis on conventional imaging. Another reader performed quantitative ADC measurements of focal pancreatic lesions and parenchyma. Wilcoxon signed-rank test was used to compare qualitative scores and ADCs between DWI sequences. Mann Whitney U-test was used to compare ADCs between the lesions and parenchyma. Results On qualitative analysis, reduced FOV DWI showed better anatomic structure visualization (2.76 ± 0.79 at b = 0 s/mm2 and 2.81 ± 0.64 at b = 400 s/mm2), lesion conspicuity (3.11 ± 0.99 at b = 0 s/mm2 and 3.15 ± 0.79 at b = 400 s/mm2), IQ score (8.51 ± 2.05 at b = 0 s/mm2 and 8.79 ± 1.60 at b = 400 s/mm2), and higher clinical utility (3.41 ± 0.64), as compared to full FOV DWI (anatomic structure, 2.18 ± 0.59 at b = 0 s/mm2 and 2.56 ± 0.47 at b = 500 s/mm2; lesion conspicuity, 2.55 ± 1.07 at b = 0 s/mm2 and 2.89 ± 0.86 at b = 500 s/mm2; IQ score, 7.13 ± 1.83 at b = 0 s/mm2 and 8.17 ± 1.31 at b = 500 s/mm2; clinical utility, 3.14 ± 0.70) (p < 0.05). Artifacts were significantly improved on reduced FOV DWI (2.65 ± 0.68) at b = 0 s/mm2 (full FOV DWI, 2.41 ± 0.63) (p < 0.001). On quantitative analysis, there were no significant differences between the 2 DWI sequences in ADCs of various pancreatic lesions and parenchyma (p > 0.05). ADCs of adenocarcinomas (1.061 × 10-3 mm2/s ± 0.133 at reduced FOV and 1.079 × 10-3 mm2/s ± 0.135 at full FOV) and neuroendocrine tumors (0.983 × 10-3 mm2/s ± 0.152 at reduced FOV and 1.004 × 10-3 mm2/s ± 0.153 at full FOV) were significantly lower than those of parenchyma (1.191 × 10-3 mm2/s ± 0.125 at reduced FOV and 1.218 × 10-3 mm2/s ± 0.103 at full FOV) (p < 0.05). Conclusion Reduced FOV DWI of the pancreas provides better overall IQ including better anatomic detail, lesion conspicuity and subjective clinical utility.

Color Doppler Twinkling Artifacts from Gallstones: In Vitro Analysis Regarding their Compositions and Architectures

The purpose of our study was to investigate the relationship between a twinkling artifact and the biochemical compositions of gallstones in phantom experiments. Fifty-two gallstones surgically extracted from 26 patients (26 cholesterol, 12 brown pigment and 14 black pigment stones) were included in the phantom study. Color Doppler sonography was performed to evaluate the occurrence of a twinkling artifact behind the stones. The artifacts were graded from grade 0 (no artifact) to grade 3 (very strong artifact). Micro computed tomography (CT) images were obtained to analyze the internal architecture and external surface of the stones. A total of 20 of 26 cholesterol stones (77%) produced grade 2 or 3 artifacts, whereas almost all the black pigment stones and more than half of the brown pigment stones produced no artifacts or grade 1 artifacts (p = 0.0010). The sensitivity and specificity of grade 2 or greater artifacts for cholesterol stones were 76.9% and 76.9%, respectively. The composition of the stones was strongly correlated with the internal shape on the micro CT image. Cholesterol stones with rough surfaces did not show stronger intensities of the artifacts than those with smooth surfaces (p > 0.05). In conclusion, most of the prominent artifacts arose from cholesterol stones having radial or radial-concentric internal architectures, whereas the black pigment stones mostly produced little artifact.

Effect of Polyglycolic Acid Mesh for Prevention of Pancreatic Fistula Following Distal Pancreatectomy: A Randomized Clinical Trial

Importance The rate of postoperative pancreatic fistula (POPF) after distal pancreatectomy ranges from 13% to 64%. To prevent POPF, polyglycolic acid (PGA) mesh was introduced, but its effect has been evaluated only in small numbers of patients and retrospective studies. Objective To evaluate the efficacy of PGA mesh in preventing POPF after distal pancreatectomy. Design, Setting, and Participants Prospective randomized clinical, single-blind (participant), parallel-group trial at 5 centers between November 2011 and April 2014. The pancreatic parenchyma was divided using a stapling device; no patient was given prophylactic octreotide. Perioperative and clinical outcomes were compared including POPF, which was graded according to the criteria of the International Study Group For Pancreatic Fistulas. A total of 97 patients aged 20 to 85 years with curable benign, premalignant, or malignant disease of the pancreatic body or tail were enrolled (44 in the PGA group and 53 in the control group). Interventions Patients in the PGA group underwent transection of the pancreas and application of fibrin glue followed by wrapping the PGA mesh around the remnant pancreatic stump. Main Outcomes and Measures The primary end point of this study was the development of a clinically relevant POPF (grade B or C by the International Study Group grading system). The secondary end point was the evaluation of risk factors for POPF. Results The study therefore evaluated a total of 97 patients, 44 in the PGA group and 53 in the control group. Thirty-nine patients were women and 58 patients were men. There were no differences in mean (SD) age (59.9 [12.0] years vs 54.5 [14.1] years, P = .05), male to female ratio (1.0:1.3 vs 1.0:1.7, P = .59), malignancy (40.9% vs 32.1%, P = .37), mean (SD) pancreatic duct diameter (1.92 [0.75] mm vs 1.94 [0.95] mm, P = .47), soft pancreatic texture (90.9% vs 83.0%, P = .17), and mean (SD) thickness of the transection margin (16.9 [5.4] mm vs 16.4 [4.9] mm, P = .63) between the PGA and control groups. The rate of clinically relevant POPF (grade B or C) was significantly lower in the PGA group than in the control group (11.4% vs 28.3%, P = .04). Conclusions and Relevance Wrapping of the cut surface of the pancreas with PGA mesh is associated with a significantly reduced rate of clinically relevant POPF. Trial Registration clinicaltrials.gov Identifier: NCT01550406.

Isolated Main Pancreatic Duct Dilatation: CT Differentiation Between Benign and Malignant Causes

OBJECTIVE The purpose of this study is to retrospectively evaluate the differential CT features of isolated benign and malignant main pancreatic duct (MPD) dilatation and to investigate whether the diagnostic performance of radiologists can be improved with knowledge of these differential CT features. MATERIALS AND METHODS Forty-one patients who had isolated MPD dilatation without any visible mass on CT from January 2000 to October 2016 were retrospectively enrolled in the study. Two radiologists reviewed CT images in consensus for the location, shape (smooth vs abrupt), length of transition, dilated pancreatic duct (PD) diameter, presence of duct penetrating sign, parenchymal atrophy, attenuation difference, associated pancreatitis, calcification, PD or common bile duct (CBD) enhancement, and perilesional cyst. The chi-square test, Fisher exact test, and t test were used to find the differential CT features of benign and malignant MPD dilatation. Two successive review sessions for differentiation between the two disease entities were then independently performed by three other reviewers with differing expertise, with the use of a 5-point confidence scale. The first session provided no information for differentiation; however, reviewers were aware of the results of univariate analyses in the second session. The diagnostic performance of the radiologists was evaluated using a pairwise comparison of ROC curves. RESULTS A total of 19 benign and 22 malignant MPD dilatations were identified. In patients with benign MPD dilatation, transition areas were frequently located in the head (57.9% [11/19] vs 13.6% [3/22], p = 0.003) and showed significantly shorter (< 6.1 mm) (78.9% [15/19] vs 9.1% [2/22], p < 0.0001) and smooth transition (89.5% [17/19] vs 9.1% [2/22], p < 0.0001). Duct penetrating sign was exclusively observed in patients with benign MPD dilatation (73.7% [14/19] vs 0% [0/22], p < 0.0001). In contrast, malignant MPD dilatation frequently was accompanied by attenuation difference (63.6% [14/22] vs 10.5% [2/19], p = 0.001) and associated PD or CBD enhancement (36.4% [8/22] vs 0% [0/19], p = 0.003). The AUC values of three reviewers significantly increased from 0.653, 0.587, and 0.884 to 0.864, 0.964, and 0.908, respectively, with knowledge of significant CT features (p = 0.013, p < 0.0001, and p = 0.701, respectively). CONCLUSION Distal, long (≥ 6.1 mm), and abrupt transition, the absence of duct penetrating sign, and the presence of attenuation difference and PD or CBD enhancement were highly suggestive CT findings for differentiation of malignant from benign MPD dilatation. The diagnostic performance of radiologists with regard to differentiation was significantly improved with knowledge of these highly suggestive CT criteria.

Erratum to: Prognostic Relevance of the Timing of Initiating and the Completion of Adjuvant Therapy in Patients with Resected Pancreatic Ductal Adenocarcinoma

Background Although the role of adjuvant therapy in patients with pancreatic ductal adenocarcinoma (PDAC) is well established, its optimal timing and duration are still controversial.

Attenuation of PERK enhances glucose-stimulated insulin secretion in islets

PERK is a pancreatic endoplasmic reticulum (ER) kinase. Its complete deletion in pancreatic β cells induces insulin deficiency; however, the effects of partial Perk suppression are unclear. We investigated the effect of partial PERK suppression using the specific PERK inhibitors GSK2606414 and GSK2656157. Low-dose GSK2606414 treatment for 24 h enhanced glucose-stimulated insulin secretion (GSIS), islet insulin content and calcium transit in mouse (at 40 nM) and human (at 50-100 nM) pancreatic islets. GSK2606414 also induced the expression of the ER chaperone BiP and the release of calcium from the ER. When Bip expression was inhibited using a Bip siRNA, the GSK2606414-induced augmentation of the ER calcium level, islet insulin contents, glucose-stimulated cytosolic calcium transit and GSIS were abrogated. In both wild-type and insulin-deficient Atg7-knockout mice, 8 weeks of GSK2656157 treatment enhanced GSIS and improved hyperglycemia without affecting body weight. In conclusion, partial PERK inhibition induced BiP expression in islets, increased glucose-stimulated calcium transit and islet insulin contents and enhanced GSIS, suggesting that low-dose PERK inhibitors could potentially be used to treat insulin deficiency.