Gaofeng Sun

Focal autoimmune pancreatitis: Radiological characteristics help to distinguish from pancreatic cancer

AIM To identify the radiological characteristics of focal autoimmune pancreatitis (f-AIP) useful for differentiation from pancreatic cancer (PC). METHODS Magnetic resonance imaging (MRI) and triple-phase computed tomography (CT) scans of 79 patients (19 with f-AIP, 30 with PC, and 30 with a normal pancreas) were evaluated retrospectively. A radiologist measured the CT attenuation of the pancreatic parenchyma, the f-AIP and PC lesions in triple phases. The mean CT attenuation values of the f-AIP lesions were compared with those of PC, and the mean CT attenuation values of pancreatic parenchyma in the three groups were compared. The diagnostic performance of CT attenuation changes from arterial phase to hepatic phase in the differentiation between f-AIP and PC was evaluated using receiver operating characteristic (ROC) curve analysis. We also investigated the incidence of previously reported radiological findings for differentiation between f-AIP and PC. RESULTS The mean CT attenuation values of f-AIP lesions in enhanced phases were significantly higher than those of PC (arterial phase: 60 ± 7 vs 48 ± 10, P < 0.05; pancreatic phase: 85 ± 6 vs 63 ± 15, P < 0.05; hepatic phase: 95 ± 7 vs 63 ± 13, P < 0.05). The mean CT attenuation values of f-AIP lesions were significantly lower those of uninvolved pancreas and normal pancreas in the arterial and pancreatic phase of CT (P < 0.001, P < 0.001), with no significant difference at the hepatic phase or unenhanced scanning (P = 0.4, P = 0.1). When the attenuation value increase was equal or more than 28 HU this was considered diagnostic for f-AIP, and a sensitivity of 87.5%, specificity of 100% and an area under the ROC curve of 0.974 (95%CI: 0.928-1.021) were achieved. Five findings were more frequently observed in f-AIP patients: (1) sausage-shaped enlargement; (2) delayed homogeneous enhancement; (3) hypoattenuating capsule-like rim; (4) irregular narrowing of the main pancreatic duct (MPD) and/or stricture of the common bile duct (CBD); and (5) MPD upstream dilation ≤ 5 mm. CONCLUSION Analysis of a combination of CT and MRI findings could improve the diagnostic accuracy of differentiating f-AIP from PC.

Infective severe acute pancreatitis: A comparison of 99mTc-ciprofloxacin scintigraphy and computed tomography

AIM To evaluate (99m)Tc-ciprofloxacin scintigraphy compared with computed tomography (CT) for detecting secondary infections associated with severe acute pancreatitis (SAP) in swine. METHODS Six healthy swine were assigned to a normal control group (group A, n = 6). SAP was induced in group B (n = 9) and C (n = 18), followed by inoculation of the resulting pancreatic necroses with inactive Escherichia coli (E. coli) (group B) and active E. coli (group C), respectively. At 7 d after inoculation, a CT scan and a series of analyses using infecton imaging (at 0.5, 1, 2, 3, 4 and 6 h after the administration of 370 MBq of intravenous infecton) were performed. The scintigrams were visually evaluated and semi-quantitatively analyzed using region of interest assignments. The differences in infecton uptake and changes in the lesion-background radioactive count ratios (L/B) in the 3 groups were recorded and compared. After imaging detection, histopathology and bacterial examinations were performed, and infected SAP was regarded as positive. The imaging findings were compared with histopathological and bacteriological results. RESULTS In group A, 6 animals survived without infection in the pancreas. In group B, 7/9 swine survived and one suffered from infection. In group C, 15/18 animals survived with infection. Hence, the number of normal, non-infected and infected SAP swine was 6, 6 and 16, respectively. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of the infecton method were 93.8% (15/16), 91.7% (11/12), 92.9% (26/28), 93.8% (15/16) and 91.7% (11/12), whereas these values for CT were 12.5% (2/16), 100.0% (12/12), 50.0% (14/28), 100.0% (2/2) and 46.2% (12/26), respectively. The changes in L/B for the infected SAP were significantly different from those of the non-infected and normal swine (P < 0.001). The mean L/B of the infectious foci at 0.5, 1, 2, 3, 4 and 6 h was 1.17 ± 0.10, 1.71 ± 0.30, 2.46 ± 0.45, 3.36 ± 0.33, 2.04 ± 0.37 and 1.1988 ± 0.09, respectively. At 3 h, the radioactive counts (2350.25 ± 602.35 k) and the mean L/B of the infectious foci were significantly higher than that at 0.5 h (P = 0.000), 1 h (P = 0.000), 2 h (P = 0.04), 4 h (P = 0.000) and 6 h (P = 0.000). CONCLUSION (99m)Tc-ciprofloxacin scintigraphy may be an effective procedure for detecting SAP secondary infections with higher sensitivity and accuracy than CT.

Establishment of a secondary infection model of severe acute pancreatitis in swine.

Objective: Develop a swine model of secondary infection in severe acute pancreatitis (SAP). Methods: Twenty-seven female swine were divided into 3 groups (1-3). In the first experiment, a SAP model was developed by retrograde injection of sodium taurocholate and trypsin into the pancreatic duct. In the second experiment, the SAP model was used to develop a secondary infection model. In groups 1 to 3, 108/mL or 104/mL Escherichia coli or saline were respectively used to inoculate necrotic areas of the pancreas using computed tomographic guidance. Biochemical, histopathological, and imaging analyses were used to characterize disease presentation. Results: The survival rate was 85.2% (23/27) during the course of the 9-day experiment. The secondary infection rates in groups 1 to 3 were 100% (8/8), 37.5% (3/8), and 14.3% (1/7), respectively. In group 1, the infection rate was significantly higher in comparison to the other 2 groups (&khgr;2 = 4.66 and 8.14, respectively, and both P < 0.05). The biochemical and histopathological parameters and computed tomographic images indicated successful development of the SAP secondary infection model. Conclusions: The swine model of SAP secondary infection was successfully developed using a 2-step method, which could serve as a platform for SAP studies that need complex experimental manipulations for longer time spans, especially for imaging research.

Active targeted dual-modal CT/MR imaging of VX2 tumors using PEGylated BaGdF5 nanoparticles conjugated with RGD

Multimodal imaging can improve the accuracy of cancer diagnosis by combining two or more imaging modalities into one system. In this study, PEGylated BaGdF5 nanoparticles (NPs) were synthesized by a hydrothermal method, and the formed PEG-BaGdF5 NPs showed good X-ray attenuation properties and positive MR contrast effects in vitro. Considering that the overexpression of integrin αvβ3 in the endothelial cells of angiogenic tumor vasculature is universal, RGD peptide, which can recognize and bind integrin αvβ3 specifically, was connected to the surface of PEG-BaGdF5 NPs. The resulting RGD-PEG-BaGdF5 NPs had good biocompatibility and a long half-life in vivo. In VX2 tumor-bearing mice, the HU values and MR signal enhancement of tumor sites in the targeted group were both higher than that in the non-targeted group after intravenous injection of RGD-PEG-BaGdF5 NPs or PEG-BaGdF5 NPs, respectively. Therefore, the RGD-PEG-BaGdF5 NPs may be used as dual-modal CT/MR contrast agents of different types of solid tumors via an active RGD-mediated vasculature targeting pathway.

Intrapancreatic accessory spleen: Evaluation with CT and MRI

The aim of the present study was to evaluate the characteristics of computed tomography (CT) and magnetic resonance imaging (MRI), particularly diffusion-weighted imaging (DWI), in the imaging of intrapancreatic accessory spleen (IPAS). The clinical and pathological records of 9 patients, including 8 patients with IPAS and 1 patient with splenosis, were reviewed. The patients had undergone plain and triple-phase enhanced CT scanning (n=9) and MRI scanning (n=8). The lesions of the 8 IPAS patients were located in the pancreatic tail, and were round (n=3), oval (n=4) or triangular (n=1) in shape. The CT and/or MRI densities, signal intensities and dynamic enhanced patterns of the lesions were similar to those of the orthotopic spleen. In DWI images (n=5), the IPAS regions presented high signal intensity (SI), and no significant difference in the apparent diffusion coefficient determined using a b-value of 600 sec/mm2 was identified between the IPAS and orthotopic spleen (P>0.05). One patient with splenosis complicated with cirrhosis had a nodule located in the pancreatic tail with an unenhanced CT value of 65 HU. In MRI examination, with the exception of the dynamic enhancement pattern, the T1-weighted, T2-weighted and DWI signals of splenosis were inconsistent with those of the normal spleen. In conclusion, in pre-contrast and post-contrast-enhanced CT and MRI images, IPAS exhibits similar characteristics to the orthotopic spleen. CT and MRI used in combination with DWI are important in the diagnosis of IPAS.

Sub‐Micrometer Au@PDA‐125I Particles as Theranostic Embolism Beads for Radiosensitization and SPECT/CT Monitoring

Au nanoparticles (3.8 ± 0.6 nm) are assembled to sub-micrometer Au particles (186.3 ± 20.4 nm) and covered with adhesive polydopamine (PDA) as embolism beads (198.8 ± 23.2 nm). Radioactive iodine-125 is labeled to Au@PDA to introduce the function of intra-irradiation. For the therapeutic effects of Au@PDA-125 I, Au particles sensitize the radiation to MHCC97H hepatoma cells and tumor-bearing mice. At the cellular level, after being treated with a relatively low-dose (5 Gy) γ-ray, Au-sensitized radiotherapy (RT) leads to an immediate increase of intracellular reactive oxygen species, accompanying with an increase of cell apoptosis. Due to the intra-irradiation, self-healing of RT-leaded DNA double-strand breakage is suppressed, inducing a further increase of cell apoptosis after RT treatment. Likewise, 3 cycles of sensitized RT leads to a valid control of tumor volume growth, but Au@PDA-125 I has no harm or radioactive residual on or in the radiosensitive organs, including the thyroid, heart, lungs, liver, and spleen. Additionally, photons emitted from 125 I and high X-ray absorption of the Au element makes the beads suitable for single photon emission computed tomography/computed tomography (SPECT/CT) imaging. Therefore, as theranostic embolism beads, Au@PDA-125 I can both enhance the therapeutic effects of external RT, and provide a real-time SPECT/CT monitoring of therapeutic time window.

Erratum to: Autoimmune pancreatitis: whole-body 18F-FDG PET/CT findings

Erratum to: Autoimmune pancreatitis: wholebody F-FDG PET/CT findings Jian Zhang, Chengwei Shao, Jianhua Wang, Chao Cheng, Changjing Zuo, Gaofeng Sun, Bin Cui, Aisheng Dong, Qinghua Liu, Lingshan Kong Department of Nuclear Medicine, Changhai Hospital, Second Military Medical University, Shanghai 200433, China Department of Radiology, Changhai Hospital, Second Military Medical University, Shanghai 200433, China