Adding liver R2* quantification to proton density fat fraction MRI of vertebral bone marrow improves the prediction of osteoporosis.

OBJECTIVES: To assess the predictive value of the combination of bone marrow (BM) proton density fat fraction (PDFF) and liver R2* for osteopenia and osteoporosis and the additional role of liver R2*. METHODS: A total of 107 healthy women were included between June 2019 and January 2021. Each participant underwent dual-energy X-ray absorptiometry (DXA) and chemical shift-encoded 3.0-T MRI. PDFF measurements were performed for each lumbar vertebral body, and R2* measurements were performed in liver segments. Agreement among measurements was assessed by Bland-Altman analysis. Receiver operating characteristic (ROC) curves were generated to select optimised cut-offs for BM PDFF and liver R2*. Univariable and multivariable logistic regressions were performed. The C statistic and continuous net reclassification improvement (NRI) were adopted to explore the incremental predictive ability of liver R2*. RESULTS: Bone mass decreased in 42 cases (39.3%) and nonbone mass decreased in 65 cases (60.7%). There were significant differences among the age groups, menopausal status groups, PDFF > 45.0% groups, and R2* > 67.7 groups. Each measurement had good reproducibility. The odds ratios (95% CIs) were 4.05 (1.22-13.43) for PDFF and 4.34 (1.41-13.35) for R2*. The C statistic (95% CI) without R2* was 0.888 (0.827-0.950), and with R2* was 0.900 (0.841-0.960). The NRI resulting from the combination of PDFF and R2* was 75.6% (p < 0.01). CONCLUSION: The predictive improvement over the use of BM PDFF and other traditional risk factors demonstrates the potential of liver R2* as a biomarker for osteopenia and osteoporosis in healthy women. KEY POINTS: • Liver R2* is a biomarker for the assessment of osteopenia and osteoporosis. • Liver R2* improved the ability to predict osteopenia and osteoporosis. • The intra- and interobserver measurements showed high agreement.

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.

Preoperative Evaluation of Malignant Perihilar Biliary Obstruction: Negative-Contrast CT Cholangiopancreatography and CT Angiography Versus MRCP and MR Angiography.

OBJECTIVE: The purpose of this study was to compare negative-contrast CT cholangiopancreatography (CTCP) and CT angiography (CTA) with MRCP and MR angiography (MRA) for the preoperative evaluation of malignant perihilar biliary obstruction. MATERIALS AND METHODS: Twenty-one patients with pathologically proven malignant perihilar biliary obstructions who had undergone both CT and MRI examinations were reviewed retrospectively. Two reviewers independently analyzed the two image sets-the negative-contrast CTCP and CTA images (i.e., CT set) and the MRCP and MRA images (i.e., MRI set)-in preoperatively evaluating the classification of malignant perihilar biliary obstruction, hepatic artery and portal vein invasion, nodal metastasis, and organ spread. The results were compared with surgical and pathologic records. RESULTS: For the classification of malignant perihilar biliary obstruction on the two image sets, the accuracy was not statistically significant (p = 1.000 for reviewer 1 and p = 0.500 for reviewer 2). For the evaluation of portal vein invasion, nodal metastasis, and organ spread, the accuracies were also not statistically significantly different (p = 0.335, 0.339, and 0.781 for reviewer 1; and p = 0.403, 0.495, and 0.325 for reviewer 2, respectively). In the assessment of hepatic artery status, the accuracy was statistically significant (p = 0.046 for reviewer 1 and p = 0.036 for reviewer 2). CONCLUSION: Compared with the MRI set, the CT set provides equivalent performance in assessing the classification of malignant perihilar biliary obstruction, portal vein involvement, nodal metastasis, and organ spread, but has higher accuracy in assessing arterial invasion.

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.

Differential diagnosis of periampullary carcinomas: comparison of CT with negative-contrast CT cholangiopancreatography versus MRI with MR cholangiopancreatography.

BACKGROUND: Negative-contrast CT cholangiopancreatography (nCTCP) has been introduced into clinical practice recently. In the present study, we compared CT with nCTCP vs. MRI with MR cholangiopancreatography (MRCP) for the differential diagnosis of periampullary carcinomas. METHODS: Fifty-nine patients with pathologically proven periampullary carcinomas who had received both CT and MR examinations before operation were reviewed retrospectively. Two reviewers independently interpreted the two image sets [the two-dimensional (2D)-CT with nCTCP set (CT set) vs. the 2D-MRI with MRCP set (MRI set)] in differentiating periampullary carcinomas, and the results were compared to the final pathologic records. RESULTS: An interobserver agreement with a weighed κ value of 0.868 for the CT set and 0.701 for the MRI set was obtained for both reviewers in this study. No statistically significant differences were observed in the accuracy of identifying each of the periampullary carcinomas of four origins (P values of 0.250, 0.500, 0.500, and 1.000 for reviewer 1 in comparison with 1.000, 0.625, 0.687, and 1.000 for reviewer 2 on the two image sets, respectively). CONCLUSION: The CT set provides a comparable performance to that of the MRI set in differentiating periampullary carcinomas, and it may be an alternative to 2D-MRI with MRCP in assessing malignant biliary obstruction in patients who are not suitable for MR examinations.

Comparison of three-dimensional negative-contrast CT cholangiopancreatography with three-dimensional MR cholangiopancreatography for the diagnosis of obstructive biliary diseases.

PURPOSE: The purpose of our study was to compare three-dimensional (3D) negative-contrast CT cholangiopancreatography (3D-nCTCP) with 3D MR cholangiopancreatography (3D-MRCP) for the diagnosis of obstructive biliary diseases. MATERIALS AND METHODS: 3D-nCTCP and 3D-MRCP were performed on seventy clinically documented obstructive biliary diseases patients. The accuracy of each technique in determining the location and cause of biliary obstruction was evaluated compared with the final clinical diagnoses. RESULTS: Both methods achieved 100% of accuracy in the diagnosis of the presence and location of biliary obstruction, and had a similar sensitivity, specificity, accuracy in differentiating benign from malignant biliary obstruction or calculous from noncalculous biliary obstruction (p>0.05). At 3D-nCTCP, six patients with stones were misinterpreted as cholangitis (N=2), papillitis (N=3), or bile duct adenocarcinoma (N=1); two metastases were mistaken as acute pancreatitis or pancreatic head carcinomas, and one intrahepatic cholangiocarcinoma was misled as bile duct adenoma. At 3D-MRCP, one small stone, one ampullary adenoma, and one intrahepatic cholangiocarcinoma were mistaken as cholangitis, ampullary stone, and intrahepatic bile duct stone, respectively, and three gallbladder carcinomas and another intrahepatic cholangiocarcinoma were misdiagnosed as hilar cholangiocarcinoma (N=3) or common hepatic duct stone (N=1); four metastases were mistaken as pancreatic head carcinomas (N=3) or distal cholangiocarcinoma (N=1). The overall accuracy in making specific diagnosis of the cause of biliary obstruction was 87.1% for 3D-nCTCP and 84.3% for 3D-MRCP, respectively, (p>0.05). CONCLUSION: 3D-nCTCP has the similar effects as 3D-MRCP for the diagnosis of biliary obstruction and, the location and the cause of biliary obstruction. In view of selected cases contraindications for MRI, 3D-nCTCP is a potential substitute.

Improvement in imaging time and quality of 3D negative-contrast computed tomography cholangiography with minimum intensity projections: application of vari-slice manual cut and erosion functions.

OBJECTIVE: To investigate the improvement in postprocessing time and image quality of 3D negative-contrast CT cholangiography (nCTC) with minimum intensity projection (minIP). METHODS: Thirty-eight patients with suspected biliary obstruction who underwent portal phase helical CT were retrospectively studied. Three-dimensional nCTC was generated using 3D tools with manual cut function in three methods: one-slice, two-slice, and vari-slice cut slab, respectively. After adjusting the threshold level to about -20 HU, the erosion function with a value of one voxel was employed each time for further cleaning up hypodense interfering voxels such as fat and air that remained and the procedure was stopped before the biliary and pancreatic ducts were overeroded. RESULTS: Mean values of the total postprocessing time of the three manual cut methods for 3D nCTC were 57.8, 29.9, and 20.6 min, respectively. After the first erosion, interfering voxels were removed in more than half of the cases and they could be primarily eliminated following the second erosion. Meanwhile, the pancreaticobiliary ducts showed obvious erosion findings at the third erosion. CONCLUSIONS: The vari-slice manual cut method was shown to be the most timesaving postprocessing method and the image quality for 3D nCTC can be improved when one to two frequencies of erosion are applied.