Diffusion-weighted magnetic resonance imaging reflects activation of signal transducer and activator of transcription 3 during focal cerebral ischemia/reperfusion.

Signal transducer and activator of transcription (STAT) is a unique protein family that binds to DNA, coupled with tyrosine phosphorylation signaling pathways, acting as a transcriptional regulator to mediate a variety of biological effects. Cerebral ischemia and reperfusion can activate STATs signaling pathway, but no studies have confirmed whether STAT activation can be verified by diffusion-weighted magnetic resonance imaging (DWI) in rats after cerebral ischemia/reperfusion. Here, we established a rat model of focal cerebral ischemia injury using the modified Longa method. DWI revealed hyperintensity in parts of the left hemisphere before reperfusion and a low apparent diffusion coefficient. STAT3 protein expression showed no significant change after reperfusion, but phosphorylated STAT3 expression began to increase after 30 minutes of reperfusion and peaked at 24 hours. Pearson correlation analysis showed that STAT3 activation was correlated positively with the relative apparent diffusion coefficient and negatively with the DWI abnormal signal area. These results indicate that DWI is a reliable representation of the infarct area and reflects STAT phosphorylation in rat brain following focal cerebral ischemia/reperfusion.

Prediction of Vascular Invasion Using a 3-Point Scale Computed Tomography Grading System in Pancreatic Ductal Adenocarcinoma: Correlation With Surgery.

OBJECTIVE: The aim of this study was to evaluate the correlation between a 3-point scale multidetector computed tomography (MDCT) grading system and surgical exploration in predicting vascular invasion and resectability in patients with pancreatic ductal adenocarcinoma (PDA). METHODS: Fifty-five patients with surgical and pathologic confirmation of PDA were retrospectively analyzed by 3 radiologists independently. All patients had MDCT examination with multiplanar reformatted images, computed tomography (CT) angiography, and negative-contrast CT cholangiopancreatography (nCTCP). A 3-point scale CT grading system and criteria for unresectability adopting the latest guidelines were used in predicting the correlation between the invasion and resectability of 5 peripancreatic vessels and surgical grade and pathology. RESULTS: Tumor location was correctly identified in all patients including 2 isodense lesions by means of nCTCP. The mean sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MDCT were 92%, 83%, 95%, 78%, and 90%, respectively, in predicting tumor resectability compared with surgery and pathology and with good agreement (κ = 0.72-0.77). A correlation was observed between CT and surgical grade in predicting vascular invasion on a per-vessel basis, and the agreement presented as good to excellent (κ = 0.66-1.00). CONCLUSIONS: A 3-point scale CT grading system is a simple and practical method in predicting peripancreatic vessel invasion and, importantly, correlates with surgical grade and pathology. Axial images combined with multiplanar reformation, nCTCP, and CT angiography can strengthen the comprehensive evaluation of PDA for resectability.

Erythropoietin reduces apoptosis of brain tissue cells in rats after cerebral ischemia/reperfusion injury: a characteristic analysis using magnetic resonance imaging.

Some in vitro experiments have shown that erythropoietin (EPO) increases resistance to apoptosis and facilitates neuronal survival following cerebral ischemia. However, results from in vivo studies are rarely reported. Perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) have been applied successfully to distinguish acute cerebral ischemic necrosis and penumbra in living animals; therefore, we hypothesized that PWI and DWI could be used to provide imaging evidence in vivo for the conclusion that EPO could reduce apoptosis in brain areas injured by cerebral ischemia/reperfusion. To validate this hypothesis, we established a rat model of focal cerebral ischemia/reperfusion injury, and treated with intra-cerebroventricular injection of EPO (5,000 U/kg) 20 minutes before injury. Brain tissue in the ischemic injury zone was sampled using MRI-guided localization. The relative area of abnormal tissue, changes in PWI and DWI in the ischemic injury zone, and the number of apoptotic cells based on TdT-mediated dUTP-biotin nick end-labeling (TUNEL) were assessed. Our findings demonstrate that EPO reduces the relative area of abnormally high signal in PWI and DWI, increases cerebral blood volume, and decreases the number of apoptotic cells positive for TUNEL in the area injured by cerebral ischemia/reperfusion. The experiment provides imaging evidence in vivo for EPO treating cerebral ischemia/reperfusion injury.

Presurgical Evaluation of Pancreatic Cancer: A Comprehensive Imaging Comparison of CT Versus MRI.

OBJECTIVE: The purpose of this study was to compare comprehensive CT and MRI in the presurgical evaluation of pancreatic cancer. MATERIALS AND METHODS: Thirty-eight patients with pathologically proven pancreatic cancer were included in a retrospective study. CT with negative-contrast CT cholangiopancreatography and CT angiography (CTA) (CT image set) versus MRI with MRCP and MR angiography (MRI image set) were analyzed independently by two reviewers for tumor detection, extension, metastasis, vascular invasion, and resectability. These results were compared with the surgical and pathologic findings. RESULTS: The rate of detection of tumors was higher with MRI than with CT but not significantly so (reviewer 1, p = 1.000; reviewer 2, p = 0.500). In the evaluation of vessel involvement, nodal status, and resectability, although CT had higher ROC AUC values than did MRI (reviewer 1, 0.913 vs 0.858, 0.613 vs 0.503, and 0.866 vs 0.774; reviewer 2, 0.879 vs 0.849, 0.640 vs 0.583, and 0.830 vs 0.815), the differences were not statistically significant (p = 0.189 vs 0.494, 0.328 vs 0.244, and 0.193 vs 0.813 for reviewers 1 and 2). In the evaluation of tumor extension and organ metastases in the 38 patients, correct diagnosis of one of two liver metastases was achieved with both image sets, one case of omental and one case of peritoneal seeding were underestimated, and one case of stomach invasion was overestimated. CONCLUSION: MRI and CT had similar performance in the presurgical evaluation of pancreatic cancer.

Differentiation of noncalculous periampullary obstruction: comparison of CT with negative-contrast CT cholangiopancreatography versus MRI with MR cholangiopancreatography.

OBJECTIVES: The purpose of this study was to compare CT with negative-contrast CT cholangiopancreatography (nCTCP) using subvolume minimum intensity projection (MinIP) versus MRI with MRCP in differentiating noncalculous periampullary obstruction. METHODS: Sixty-four patients with clinically proven noncalculous periampullary obstructions who had undergone both MDCT and MR examinations before operation were reviewed retrospectively. Two reviewers independently interpreted the two image sets (the CT with nCTCP set [CT set] vs. the MRI with MRCP set [MRI set]) in differentiating both benign from malignant obstruction and pancreatic head carcinoma (PHC) from non-PHC, and the results were compared to the final clinical records. RESULTS: In this study, no statistically significant differences were observed in the accuracy of differentiating benign from malignant periampullary obstruction (p = 0.754 for reviewer 1 and p = 0.508 for reviewer 2) on the two image sets. The accuracy of differentiating PHC from non-PHC was also statistically insignificant (p = 0.125 for reviewer 1 and p = 1.000 for reviewer 2) on the two image sets. CONCLUSION: The CT set provides a comparable performance to that of the MRI set in differentiating noncalculous periampullary obstruction. KEY POINTS: • nCTCP with subvolume MinIP is a practical tool in evaluating biliary obstruction • Two image sets have a comparable performance in differentiating noncalculous periampullary obstruction • MDCT could serve as an alternative in patients not eligible for MRI.