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Objective To investigate the feasibility of b value threshold maps based on MRI diffusion weighted imaging ( DWI ) in the diagnosis of pancreatic adenocarcinoma .Methods The preoperative MRI DWI [ b value=0( b0 ) and 1000 ( b1000 ) s/mm2 ] data of 14 patients who were postoperatively histologically confirmed as pancreatic ductal adenocarcinoma from September 2016 to May 2015 admitted in Shanghai Changhai Hospital were retrospectively analyzed .The b value threshold maps were calculated .Computed DWI images at b value of 1500 s/mm2 ( cDWIb1500 ) was calculated based on the scanned DWI images of b 0 and b1000 s/mm2 . The efficacy of DWIb 1000 , b value threshold map and cDWIb 1500 in manifesting pancreatic adenocarcinoma was assessed by a four-point scale .The non-parametric Friedman test was used to compare the three methods , and Conover adjusted method was applied to compare any two of the three methods .Results The conspicuity score of DWIb 1000 , b value threshold map and cDWIb 1500 in showing pancreatic cancer was 2.9 ±0.8, 3.7 ±0.5 and 3.6 ±0.5, respectively, and the differences among the three methods were statistically significant (F=19.5, P value <0.001), but the differences on tumor conspicuity scores of b value threshold map and cDWIb 1500 were not statistically different .Conclusions The calculation of b value threshold map based on DWI images could show pancreatic cancer in high contrast quickly by adjusting window width and window level , and could achieve comparable performance as cDWIb 1500 .
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Objective To investigate the feasibility of computer-aided pancreas segmentation based on three-dimensional (3D) Dixon MRI at 3.0-T.Methods Five volunteers with health pancreas underwent upper abdominal 3D Dixon MRI at 3.0T with the same scan parameters while holding breath.The automatic segmentation of pancreas is based on the Medical Imaging Interaction ToolKit (MITK) with homemade software.A experienced radiologist performed manual segmentation and computer aided segmentation of the pancreas on the opposed phase and water phase images twice.Similarity was analyzed and compared for the manual and automated segmentations for the two group images.Similarity was presented as Dice coefficients.Results Both of the oppose phase and water phase images of Dixon MRI showed that the signal intensity of pancreas was higher than that of the surrounding tissue,the similarity of water phase was obviously higher than that of oppose phase and the differences were statistically significant.Based on Dixon MRI water phase and oppose phase images,the mean dice coefficients for the manual segmentations were 0.81 ± 0.01 and 0.85 ±0.03,respectively,for both the oppose phase and water phase images (P=0.013).For the automated segmentations,the dice coefficients were 0.69 ± 0.08 and 0.75 ± 0.03 for water phase images and the oppose images,respectively,and the difference was not statistically significant (P =0.155).Conclusions 3.0T oppose phase and water phase of Dixon images could clearly show the pancreas,and automated pancreas segmentation based on water phase Dixon MRI obtained higher similarity,which was feasible.
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Objective To investigate the feasibility of pancreatic DWI at a 3T MR imager and its value for the qualitative diagnosis of pancreatic tumors. Methods For 20 normal healthy volunteers and 47 patients with pancreatic tumors [21 pancreatic carcinoma (PC), 7 mass-forming chronic pancreatitis (MFCP)and 19 cystic lesions), routine pancreatic MRI and pancreatic DWI using b values (500 and 1000 mm2/s)were obtained, the DWI signal intensity (SI) and apparent diffusion coefficient (ADC) value of pancreatic lesions and adjacent tissue was measured. Results In the b = 500 and 1000 mm2/s DWI images, there was no significant difference in ADC value between different parts of normal pancreas. But PC and MFCP were shown as hyperintensity mass, in addition, the related SI1000 of PC at b = 1000 mm2/s DWI was significantly higher than that of MFCP (1.238 +0.448 vs. 0.371 +0.293, P＜0. 01). Compared with normal pancreas,beth PC and MFCP presented as decreased ADC500 and ADC1000 value. The ADC1000 of PC was significantly lower than that of MFCP [ ( 1. 087 + 0. 175 ) mm2/s vs. ( 1. 279 ± 0.213 ) mm2/s]. Pancreatic cystic lesions were shown as hyperintensity in DWI at b = 500 mm2/s, but were depicted as iso-intense signal or low-signal lesions in DWI using b = 1000 mm2/s. Both ADC500 and ADC1000 of pancreatic cystic lesions were higher than that of normal pancreas. Conclusions 3T-MR DWI is helpful to differentiate pancreatic lesions. High b value DWI is more valuable for the qualitative diagnosis of pancreatic mass.
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Objective To explore the feasibility of contrast enhanced-MRA (CE-MRA) in testifying atherosclerosis model of rabbits with Care-bolus. Methods A total of 24 female New Zealand rabbits were fed with high cholesterol diet for 8 weeks. The whole body arteries of rabbits were inspected with CE-MRA and Care-bolus technology at 1.5T MR scanner before and after high cholesterol diet, and the images were compared accordingly. The survival conditions of rabbits were observed 1 week after scanning, and then the arteries with appeared plaques and angiostegnosis level more than 50% were taken out, sliced and dyed. Results No rabbit died unexpectedly during the study. Before feeding with high cholesterol diet, the arteries were smooth and lumens uniformity. After feeding high cholesterol diet, the inner walls of all aorta became rugose. The lumen stenosis of 32 common carotid arteries, 10 superior mesenteric arteries and 36 renal arteries were more than 50%. Pathological slices showed that 100% vessel had plaques. Compared with pathological findings, CE-MRA exaggerated lumen stenosis level in 26.92%, but no more than 25%. Conclusion To testify atherosclerosis model of rabbits using CE-MRA with Care-blous technology is reliable, causing tiny trauma and good at animal survival rate.
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Objective To evaluate the clinical value of three-dimensional contrast-enhanced MR angiography (3D CE-MRA) in the diagnosis and treatment of visceral artery aneurysms. Methods Forty-three patients with visceral artery aneurysms underwent 3D CE-MRA sequence after injection of 0. 2 mmol Gd-DTPA per kg. bw. The source images were subtracted and transferred to computer workstation subsequently post-procession. Digital subtraction angiography (DSA) was performed in 19 patients simultaneously for the purpose of control study. Results There were 43 cases with 50 visceral artery aneurysms. The arteries involved were 32 splenic artery aneurysms accounting for 64% including 5 anomalously arising from superior mesenteric artery; 7 of superior mesenteric ( 14% ) ; 4 celiac ( 1 from celiomesenteric trunk), 5 of renal and 2 of hepatic. 3D CE-MRA clearly demonstrated aneurysm's location, size, morphology, and was superior to DSA in three-dimensional display of aneurysrn and its relationship with surrounding vessels and involved organs. Endovascular treatment was performed in 15 patients, surgical treatment in 9, and conservative therapy only in 19. Conclusion 3D CE-MRA is a noninvasive and accurate technique for the diagnosis of visceral artery aneurysms. Its three-dimensional anatomic information is very helpful for treatment planning. 3D CE-MRA could be used as a test of choice in the evaluation of visceral artery aneurysms.
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Objective To assess the clinical value of three dimensional dynamic contrast enhanced MR angiography (3D DCE MRA) in the detection for intracranial aneurysm. Methods 3D DCE MRA was performed in 54 patients highly suspected with intracranial aneurysms. Then conventional digital subtraction angiography (DSA) and feasible endovascular treatment were performed simultaneously. A three dimensional fast imaging with steady state precession (3D FISP) was used for 3D DCE MRA(Gd DTPA dose, 0.2 mmol per kilogram for body weight; acquisition time, 10 seconds). The source images were subtracted from mask images and transferred to computer workstation. All images were subsequently post processed using three dimensional reconstruction. 3D DCE MRA images and DSA images were compared for demonstration of the aneurysm, its neck, and relationship with parent artery, and the usefulness for endovascular treatment was evaluated. Results There were 39 cases with 45 intracranial aneurysms. The sensitivity, specificity, and accuracy of 3D DCE MRA were 96%, 73%, and 90%, respectively. Aneurysm and its neck depiction at 3D DCE MRA was significantly better than that at DSA, especially for aneurysms adjacent to the cavernous sinus and near the PICA of vertebral artery. 3D DCE MRA could guide neurosurgeons to the desired DSA projection, and helped them make plan for interventional or surgical treatment in advance. But the diagnosis should be very carefully made for small aneurysms located in the periphery and the arterial bifurcation. Conclusion 3D DCE MRA is a fast, noninvasive and efficient technique for diagnosing intracranial aneurysms. Its three dimensional information is helpful for DSA demonstration and treatment planning. Any uncertain diagnosis requires DSA confirmation.