Feasibility of computer-aided pancreas segmentation based on three dimensional Dixon MRI / 中华胰腺病杂志

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.

Morphologic characteristics of atherosclerotic basilar arteries at 3.0T high-resolution MRI / 实用放射学杂志

Objective To explore the remodeling modes and the plaque distribution of atherosclerotic BA at 3.0T high resolution MRI.Methods 90 symptomatic patients with atherosclerotic stenosis of BA on digital subtraction angiography (DSA) (50 ％-99 ％) were recruited consecutively.Luminal area,vessel area of maximal narrow sites and the reference sites were measured.The differences of involved imaging parameters between negative group and positive group were analyzed.Results 51 patients with required imaging quality were enrolled finally.Among the 51 patients,the rate of positive remodeling cases was 72.5％ (37/51) and negative remodeling took over 27.5％ (14/51).Compared with the negative remodeling group,the positive remodeling group had greater plaque size,larger plaque burden percentage,and higher maximal wall thickness at maximal lumen narrowing sites.The plaques were mainly located at ventral wall of the vessel.Conclusion 3.0T high-resolution MR imaging could be applied in assessing the remodeling modes and plaque distribution of BA stenosis.

MRI molecular imaging targeting P selectin in severity grading of acute pancreatitis in rats / 中华胰腺病杂志

Objective To investigate the application of MRI targeting contrast agent ( P-Gd-Probe) for P selectin in evaluating the severity grades of acute pancreatitis (AP).Methods L-arginine solution (100mg/100kg) were intraperitoneally injected for 3 times once an hour to establish AP model in SD rats. Control group was injected with normal saline in a equal volume .All rats were divided into acute edematous pancreatitis (AEP) group (6 h and 12 h after model establishment)and acute necrotizing pancreatitis (ANP) group (24 h and 48 h after model establishment ) based on the pathology .The rats were examined by T 1 WI plain and enhanced scanning at 6 h, 12 h, 24 h and 48 h after injection , and P-Gd-probe was as the enhanced contrast agent.The signal noise ratio ( SNR) of the pancreas were measured before and after enhancement .Then the pancreas tissues were harvested for pathological examination and P selectin expression in pancreatic tissue was detected using immunohistochemical analysis .Results Inflammation was observed in pancreatic tissue at 6h after establishment , and became more serious as the modeling time extended .P selectin expression was increased as pancreatitis inflammation became more serious .The SNR of control group was stable before and after enhancement.The SNR before and after enhancement was 17.22 ±1.35 and 37.38 ±1.66 in AEP group, and 16.29 ±1.39 and 58.18 ±1.03 in ANP group.The SNR after enhancement was higher than that before enhancement, and the differences were significantly different ( t=-49.59 and -86.09, P<0.001 ). Conclusions Monoclonal antibody MRI contrast agent targeting P selectin is helpful in evaluating the severity of AP.

Analysis of CT findings of benign and malignant pancreatic neuroendocrine tumors / 中华胰腺病杂志

Objective To explore the CT findings of benign and malignant pancreatic neuroendocrine tumors and improve its diagnostic accuracy.Methods The clinical information and enhanced CT findings of 96 cases with pathologically-proved pancreatic neuroendocrine tumors were retrospectively reviewed.The CT findings were evaluated by several factors,which included tumor size,morphology,location,internal composition,calcification,separation,bile duct and pancreatic duct dilation and CT value.Results All cases were divided into benign or malignant according to pathological grades,and benign group involved 40 cases with 41 lesions,while malignant group involved 56 cases with 59 lesions.The size of malignant lesions was significantly larger than that of benign lesions (median size 6.0 cm vs 2.2 cm),the shape of the lesions was irregular,and was mainly cystic solid,and mottling,curve shape,clumps calcification was present,then the bile duct and pancreatic duct was mild to moderately dilated,and the difference between the two groups was statistically significant (P ＜0.05).But the difference of tumor location,separation was not significant.45.76％ (27/59) of the malignant lesions reached the peak value in arterial phase,and 44.07％ (26/59) reached the peak value in venous phase;while 68.29％ (28/41) of the benign lesions reached the peak value in arterial phase,and 31.71％ (13/41) reached the peak value in venous phase.The CT values of malignant lesions in plain CT scanning,arterial phase,venous phase,balance phase were (39.02 ±7.53),(121.20 ± 54.73),(125.25 ± 40.77),(101.41 ± 28.68) Hu,while they were (41.49 ± 8.59),(144.73 ± 53.95),(157.05 ±44.72),(121.02 ±29.80) Hu in benign group.In plain CT scanning,the difference of CT value between malignant and benign lesions was not significant;but in the enhanced phase,the CT value of malignant lesions was significantly lower than that of benign lesions,and the difference was statistically significant (P ＜ 0.05).Conclusions The lesion with its size ≥ 3.0 cm,irregnlar morphology,cystic necrosis,calcification,pancreatic and bile duct dilatation is suggestive of malignancy tumor.The average CT values of malignant group are lower than those of the benign group in arterial,venous and balance phases.