Tian Wu Chen

Abdominal MRI at 3.0 T: LAVA-Flex compared with conventional fat suppression T1-weighted images.

To study liver imaging with volume acceleration‐flexible (LAVA‐Flex) for abdominal magnetic resonance imaging (MRI) at 3.0 T and compare the image quality of abdominal organs between LAVA‐Flex and fast spoiled gradient‐recalled (FSPGR) T1‐weighted imaging.

Functional Magnetic Resonance Imaging in Acute Kidney Injury: Present Status

Acute kidney injury (AKI) is a common complication of hospitalization that is characterized by a sudden loss of renal excretory function and associated with the subsequent development of chronic kidney disease, poor prognosis, and increased mortality. Although the pathophysiology of renal functional impairment in the setting of AKI remains poorly understood, previous studies have identified changes in renal hemodynamics, perfusion, and oxygenation as key factors in the development and progression of AKI. The early assessment of these changes remains a challenge. Many established approaches are not applicable to humans because of their invasiveness. Functional renal magnetic resonance (MR) imaging offers an alternative assessment tool that could be used to evaluate renal morphology and function noninvasively and simultaneously. Thus, the purpose of this review is to illustrate the principle, application, and role of the techniques of functional renal MR imaging, including blood oxygen level-dependent imaging, arterial spin labeling, and diffusion-weighted MR imaging, in the management of AKI. The use of gadolinium in MR imaging may exacerbate renal impairment and cause nephrogenic systemic fibrosis. Therefore, dynamic contrast-enhanced MR imaging will not be discussed in this paper.

Liver dynamic contrast-enhanced MRI for staging liver fibrosis in a piglet model.

To determine whether dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) could monitor progression of liver fibrosis in a piglet model, and which DCE‐MRI parameter is most accurate for staging this disease.

GRE T2-Weighted MRI: Principles and Clinical Applications

The sequence of a multiecho gradient recalled echo (GRE) T2*-weighted imaging (T2*WI) is a relatively new magnetic resonance imaging (MRI) technique. In contrast to T2 relaxation, which acquires a spin echo signal, T2* relaxation acquires a gradient echo signal. The sequence of a GRE T2*WI requires high uniformity of the magnetic field. GRE T2*WI can detect the smallest changes in uniformity in the magnetic field and can improve the rate of small lesion detection. In addition, the T2* value can indirectly reflect changes in tissue biochemical components. Moreover, it can be used for the early diagnosis and quantitative diagnosis of some diseases. This paper reviews the principles and clinical applications as well as the advantages and disadvantages of GRE T2*WI.

The Effect of Superparamagnetic Iron Oxide with iRGD Peptide on the Labeling of Pancreatic Cancer Cells In Vitro: A Preliminary Study

The iRGD peptide loaded with iron oxide nanoparticles for tumor targeting and tissue penetration was developed for targeted tumor therapy and ultrasensitive MR imaging. Binding of iRGD, a tumor homing peptide, is mediated by integrins, which are widely expressed on the surface of cells. Several types of small molecular drugs and nanoparticles can be transfected into cells with the help of iRGD peptide. Thus, we postulate that SPIO nanoparticles, which have good biocompatibility, can also be transfected into cells using iRGD. Despite the many kinds of cell labeling studies that have been performed with SPIO nanoparticles and RGD peptide or its analogues, only a few have applied SPIO nanoparticles with iRGD peptide in pancreatic cancer cells. This paper reports our preliminary findings regarding the effect of iRGD peptide (CRGDK/RGPD/EC) combined with SPIO on the labeling of pancreatic cancer cells. The results suggest that SPIO with iRGD peptide can enhance the positive labeling rate of cells and the uptake of SPIO. Optimal functionalization was achieved with the appropriate concentration or concentration range of SPIO and iRGD peptide. This study describes a simple and economical protocol to label panc-1 cells using SPIO in combination with iRGD peptide and may provide a useful method to improve the sensitivity of pancreatic cancer imaging.

Albumin and magnetic resonance imaging-liver volume to identify hepatitis B-related cirrhosis and esophageal varices

AIM To investigate whether liver lobe volume and albumin (ALB) could predict the presence and severity of liver cirrhosis, and esophageal varices. METHODS Seventy-one cirrhotic patients with hepatitis B and 21 healthy individuals were enrolled in this study. All the participants underwent abdominal enhanced magnetic resonance imaging to measure each liver lobe volume, and biochemical workup for testing ALB and Child-Pugh class. All cirrhotic patients underwent upper gastrointestinal endoscopy to show the presence of cirrhotic esophageal varices. Right liver lobe volume (RV), left medial liver lobe volume (LMV), left lateral liver lobe volume (LLV), and caudate lobe volume (CV) were measured using enhanced magnetic resonance imaging. The ratios of RV to ALB (RV/ALB), LMV to ALB (LMV/ALB), LLV to ALB (LLV/ALB) and CV to ALB (CV/ALB) were calculated. Statistical analyses were performed to determine whether and how the combination of liver lobe volume measured using magnetic resonance imaging and albumin could predict the presence and severity of liver cirrhosis, and the presence of esophageal varices. RESULTS RV, LMV, LLV and CV decreased (r = -0.51-0.373; all P < 0.05), while RV/ALB increased (r = 0.424; P < 0.05), with the progress of Child-Pugh class of liver cirrhosis. RV, LMV, CV, LLV/ALB and CV/ALB could identify presence of liver cirrhosis; LLV and LMV could distinguish Child-Pugh class A from B; RV, LMV, LLV, CV, RV/ALB and LLV/ALB could distinguish class A from C; RV and LLV/ALB could differentiate B from C; and RV, RV/ALB and CV/ALB could identify presence of esophageal varices (all P < 0.05). Among these parameters, CV/ALB could best identify the presence of liver cirrhosis, with an area under receiver operating characteristic curve (AUC) of 0.860, a sensitivity of 82.0% and a specificity of 83.0%. LLV could best distinguish class A from B, with an AUC of 0.761, a sensitivity of 74.4% and a specificity of 73.1%. RV could best distinguish class A from C, with an AUC of 0.900, a sensitivity of 90.3% and a specificity of 84.5%. LLV/ALB could best distinguish class B from C, with an AUC of 0.900, a sensitivity of 93.8% and a specificity of 81.5%. RV/ALB could best identify esophageal varices, with an AUC of 0.890, a sensitivity of 80.0% and a specificity of 83.5%. CONCLUSION The combination of liver lobe volume and ALB has potential to identify presence and severity of cirrhosis, and presence of esophageal varices.

Pancreatic Duct Patterns in Acute Pancreatitis: A MRI Study

Objectives To study the MRI findings of the pancreatic duct in patients with acute pancreatitis. Materials and Methods A total of 239 patients with acute pancreatitis and 125 controls were analyzed in this study. The severity of acute pancreatitis was graded using the MR severity index (MRSI) and the Acute Physiology And Chronic Healthy Evaluation II(APACHE II) scoring systems. The number of main pancreatic duct (MPD) segments visualized, and both MPD diameter and pancreatic duct disruption were noted and compared with the severity of acute pancreatitis. Results The frequency of MPD segment visualization in the control group was higher than that in the acute pancreatitis group (p<0.05). The number of MPD segments visualized was negatively correlated with the MRSI score (p<0.05) and the APACHE II score (p<0.05). There was no difference in the MPD diameter between the acute pancreatitis and control groups or among the patients with different severities of acute pancreatitis (p>0.05). The prevalence of pancreatic duct disruption was 7.9% in the acute pancreatitis group. The prevalences of pancreatic duct disruption were 4.8% and 15.3% in the mild and severe acute pancreatitis groups based on the APACHE II score, respectively, and were 0%, 5.7% and 43.5% in the mild, moderate and severe acute pancreatitis groups according the MRSI score, respectively. The prevalence of pancreatic duct disruption was correlated with the severity of acute pancreatitis based on the APACHE II score (p<0.05) and MRSI score (p<0.05). Conclusion The pancreatic duct in acute pancreatitis patients was of normal diameter. The number of MPD segments visualized and visible pancreatic duct disruption on MRI may be supplementary indicators for determining the severity of acute pancreatitis.

The Blood Oxygenation T2* Values of Resectable Esophageal Squamous Cell Carcinomas as Measured by 3T Magnetic Resonance Imaging: Association with Tumor Stage

Objective To explore the association between the blood oxygenation T2* values of resectable esophageal squamous cell carcinomas (ESCCs) and tumor stages. Materials and Methods This study included 48 ESCC patients and 20 healthy participants who had undergone esophageal T2*-weighted imaging to obtain T2* values of the tumors and normal esophagi. ESCC patients underwent surgical resections less than one week after imaging. Statistical analyses were performed to identify the association between T2* values of ESCCs and tumor stages. Results One-way ANOVA and Student-Newman-Keuls tests revealed that the T2* value could differentiate stage T1 ESCCs (17.7 ± 3.3 ms) from stage T2 and T3 tumors (24.6 ± 2.7 ms and 27.8 ± 5.6 ms, respectively; all ps < 0.001). Receiver operating curve (ROC) analysis showed the suitable cutoff T2* value of 21.3 ms for either differentiation. The former statistical tests demonstrated that the T2* value could not differentiate between stages T2 and T3 (24.6 ± 2.7 ms vs. 27.8 ± 5.6 ms, respectively, p > 0.05) or between N stages (N1 vs. N2 vs. N3: 24.7 ± 6.9 ms vs. 25.4 ± 4.5 ms vs. 26.8 ± 3.9 ms, respectively; all ps > 0.05). The former tests illustrated that the T2* value could differentiate anatomic stages I and II (18.8 ± 4.8 ms and 26.9 ± 5.9 ms, respectively) or stages I and III (27.3 ± 3.6 ms). ROC analysis depicted the same cutoff T2* value of 21.3 ms for either differentiation. In addition, the Students t test revealed that the T2* value could determine grouped T stages (T0 vs. T1–3: 17.0 ± 2.9 ms vs. 25.2 ± 6.2 ms; T0–1 vs. T2–3: 17.3 ± 3.0 ms vs. 27.1 ± 5.3 ms; and T0–2 vs. T3: 18.8 ± 4.2 ms vs. 27.8 ± 5.6 ms, all ps < 0.001). ROC analysis indicated that the T2* value could detect ESCCs (cutoff, 20 ms), and discriminate between stages T0–1 and T2–3 (cutoff, 21.3 ms) and between T0–2 and T3 (cutoff, 20.4 ms). Conclusion The T2* value can be an additional quantitative indicator for detecting ESCC except for stage T1 cancer, and can preoperatively discriminate between some T stages and between anatomic stages of this tumor.

Platelet count combined with right liver volume and spleen volume measured by magnetic resonance imaging for identifying cirrhosis and esophageal varices.

AIM To determine whether the combination of platelet count (PLT) with spleen volume parameters and right liver volume (RV) measured by magnetic resonance imaging (MRI) could predict the Child-Pugh class of liver cirrhosis and esophageal varices (EV). METHODS Two hundred and five cirrhotic patients with hepatitis B and 40 healthy volunteers underwent abdominal triphasic-enhancement MRI and laboratory examination of PLT in 10(9)/L. Cirrhotic patients underwent endoscopy for detecting EV. Spleen maximal width (W), thickness (T) and length (L) in mm together with spleen volume (SV) and RV in mm(3) were measured by MRI, and spleen volume index (SI) in mm(3) was obtained by W × T × L. SV/PLT, SI/PLT and RV × PLT/SV (RVPS) were calculated and statistically analyzed to assess cirrhosis and EV. RESULTS SV/PLT (r = 0.676) and SI/PLT (r = 0.707) increased, and PLT (r = -0.626) and RVPS (r = -0.802) decreased with the progress of Child-Pugh class (P < 0.001 for all). All parameters could determine the presence of cirrhosis, distinguish between each class of Child-Pugh class, and identify the presence of EV [the areas under the curve (AUCs) = 0.661-0.973]. Among parameters, RVPS could best determine presence and each class of cirrhosis with AUCs of 0.973 and 0.740-0.853, respectively; and SV/PLT could best identify EV with an AUC of 0.782. CONCLUSION The combination of PLT with SV and RV could predict Child-Pugh class of liver cirrhosis and identify the presence of esophageal varices.

Acute pancreatitis with gradient echo T2*-weighted magnetic resonance imaging.

BACKGROUND To study gradient recalled echo (GRE) T2*-weighted imaging (T2*WI) for normal pancreas and acute pancreatitis (AP). METHODS Fifty-one patients without any pancreatic disorders (control group) and 117 patients with AP were recruited. T2* values derived from T2*WI of the pancreas were measured for the two groups. The severity of AP was graded by the magnetic resonance severity index (MRSI) and the Acute Physiology and Chronic Healthy Evaluation II (APACHE II) scoring system. Logistic regression was used to analyze the relationship between the T2* values and AP severity. The usefulness of the T2* value for diagnosing AP and the relationship between the T2* values and the severity of AP were analyzed. RESULTS On GRE-T2*WI, the normal pancreas showed a well-marinated and consistently homogeneous isointensity. Edematous AP, as well as the non-necrotic area in necrotizing AP, showed ill-defined but homogeneous signal intensity. AP with pancreatic hemorrhage showed a decreased T2* value and a signal loss on the signal decay curve. The T2* value of pancreas in the AP group was higher than that of the control group (t=-8.20, P<0.05). The T2* value tended to increase along with the increase in MRSI scores but not with the APACHE II scores (P>0.05). AP was associated with a one standard deviation increment in the T2* value (OR =1.37; 95% CI: 1.216-1.532). CONCLUSIONS T2*WI demonstrates a few characteristics of the normal pancreas and AP, which could potentially be helpful for detecting hemorrhage, and contributes to diagnosing AP and its severity.