Comparison of Magnetic Resonance Elastography and Diffusion-weighted Imaging for Staging Hepatic Fibrosis

Background:

To compare the diagnostic values of magnetic resonance elastography (MRE) and diffusion-weighted imaging (DWI) in staging hepatic fibrosis (HF) in an animal model.

Methods:

This study consisted of 44 rabbits served as HF group and 9 normal rabbits. HF group was divided into two subgroups: Group A (n = 32) and Group B (n = 12). Rabbits in Group B were served as a complementary group when rabbits in Group A suddenly died during the study. Rabbits from control and Group A underwent abdominal MR imaging (MRI), MRE, and DWI. In Group A, random eight rabbits underwent MRI examinations at 4, 5, 6, 10 weeks after carbon tetrachloride oil subcutaneous injection. Liver stiffness (LS) and apparent diffusion coefficient (ADC) values of liver parenchyma were measured. The diagnostic performance of MRE and DWI for staging HF was compared using the receiver operating characteristic curve analysis on the basis of the histopathological analysis of HF.

Results:

Significant differences of LS and DWI values were present among HF stages (P < 0.005). The LS values measured on MRE (r = 0.838, P < 0.001) were more strongly correlated with the HF stages than with ADC values (r = −0.527, P < 0.001). The area under the receiver operating characteristic curve values of LS were significantly larger than those of DWI were for discriminating two stages of HF (0.979 vs. 0.712 for ≥ S1, 0.922 vs. 0.699 for ≥ S2). MRE showed higher specificity for predicting all stages of HF compared to DWI.

Conclusions:

MRE more strongly correlated with the HF stages than DWI and is more specific in predicting all HF stages.     

Diagnostic Utility of Diffusion-weighted Magnetic Resonance Imaging in Differentiating Small Solid Renal Tumors (≤4 cm) at 3.0T Magnetic Resonance Imaging

Background:

The aim of this study was to assess the performance of apparent diffusion coefficient (ADC) measurement obtained with diffusion-weighted magnetic resonance imaging (DW-MRI) to distinguish renal cell carcinomas (RCCs) from small benign solid renal tumors (≤4 cm).

Methods:

In this cross-sectional study, 49 consecutive patients with histopathologically confirmed small solid renal tumors, and seven healthy volunteers were imaged using nonenhanced MRI and DW-MRI. The ADC map was calculated using the b values of 0, 50, 400, and 600 s/mm² and values compared via the Kruskal–Wallis and Mann–Whitney tests. The utility of ADC for differentiating RCCs and benign lesions was assessed using a receiver operating characteristic curve. Multiple nonenhanced MRI features were analyzed by Logistic regression.

Results:

The tumors consisted of 33 cases of clear-cell RCCs (ccRCCs) and 16 cases of benign tumors, including 14 cases of minimal fat angiomyolipomas and 2 cases of oncocytomas. The ADCs showed significant differences among benign tumors ([0.90 ± 0.52] × 10⁻³ mm²/s), ccRCCs ([1.53 ± 0.31] × 10⁻³ mm²/s) and the normal renal parenchyma ([2.22 ± 0.12] × 10⁻³ mm²/s) (P < 0.001). Moreover, there was statistically significant difference between high and low-grade ccRCCs (P = 0.004). Using a cut-off ADC of 1.36 × 10⁻³ mm²/s, DW-MRI resulted in an area under the curve (AUC), sensitivity, and specificity equal to 0.839, 75.8%, and 87.5%, respectively. Nonenhanced MRI alone and the combination of imaging methods led to an AUC, sensitivity and specificity equal to 0.919, 93.9%, and 81.2%, 0.998, 97%, and 100%, respectively. The Logistic regression showed that the location of the center of the tumor (inside the contour of the kidney) and appearance of stiff blood vessel were significantly helpful for diagnosing ccRCCs.

Conclusions:

DW-MRI has potential in distinguishing ccRCCs from benign lesions in human small solid renal tumors (≤4 cm), and in increasing the accuracy for diagnosing ccRCCs when combined with nonenhanced MRI.     

Effects of Immunosuppressants on Immune Response to Vaccine in Inflammatory Bowel Disease

Objective:

To evaluate the response rate to vaccination in different treatment groups (nonimmunosuppressants and immunosuppressants).

Data Sources:

We completed an online systematic search using PubMed to identify all articles published in English between January 1990 and December 2013 assessing the effect of the response rate to vaccination in different treatment groups (with and without immunomodulators). The following terms were used: “inflammatory bowel disease (IBD)” OR “Crohn''s disease” OR “ulcerative colitis” AND (“vaccination” OR “vaccine”) AND (“corticosteroids” OR “mercaptopurine” OR “azathioprine” OR “methotrexate [MTX]”) AND “immunomodulators.”

Study Selection:

The inclusion criteria of articles were that the studies: (1) Randomized controlled trials which included patients with a diagnosis of IBD (established by standard clinical, radiographic, endoscopic, and histologic criteria); (2) exposed patients received immunomodulators for maintenance (weight-appropriate doses of 6-mercaptopurine/azathioprine or within 3 months of stopping, 15 mg or more MTX per week or within 3 months of stopping; (3) exposed patients received nonimmunomodulators (no therapy, antibiotics only, mesalazine only, biological agent only such as infliximab, adalimumab, certolizumab or natalizumab or within 3 months of stopping one of these agents). The exclusion criteria of articles were that the studies: (1) History of hepatitis B virus (HBV), influenza or streptococcus pneumoniae infection; (2) patients who had previously been vaccinated against HBV, influenza or streptococcus pneumoniae; (3) any medical condition known to cause immunosuppression (e.g. chronic renal failure and human immunodeficiency virus infection); (4) individuals with positive hepatitis markers or liver cirrhosis; (5) patients with a known allergy to eggs or other components of the vaccines and (6) pregnancy.

Results:

Patients treated with immunomodulators were associated with lower response rates to vaccination.

Conclusions:

Immunomodulators may impair the immune response to vaccination in patients with IBD. Vaccination should be made at the time of diagnosis or before starting immunosuppressed therapy.     

Improved Performance in Differentiating Benign from Malignant Sinonasal Tumors Using Diffusion-weighted Combined with Dynamic Contrast-enhanced Magnetic Resonance Imaging

Background:

Differentiating benign from malignant sinonsal lesions is essential for treatment planning as well as determining the patient''s prognosis, but the differentiation is often difficult in clinical practice. The study aimed to determine whether the combination of diffusion-weighted (DW) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can improve the performance in differentiating benign from malignant sinonasal tumors.

Methods:

This retrospective study included 197 consecutive patients with sinonasal tumors (116 malignant tumors and 81 benign tumors). All patients underwent both DW and DCE-MRI in a 3-T magnetic resonance scanner. Two different settings of b values (0,700 and 0,1000 s/mm²) and two different strategies of region of interest (ROI) including whole slice (WS) and partial slice (PS) were used to calculate apparent diffusion coefficients (ADCs). A DW parameter with WS ADCs_b0,1000 and two DCE-MRI parameters (time intensity curve [TIC] and time to peak enhancement [Tpeak]) were finally combined to use in differentiating the benign from the malignant tumors in this study.

Results:

The mean ADCs of malignant sinonasal tumors (WS ADCs_b0,1000 = 1.084 × 10⁻³ mm²/s) were significantly lower than those of benign tumors (WS ADCs_b0,1000 = 1.617 × 10⁻³ mm²/s, P < 0.001). The accuracy using WS ADCs_b0,1000 alone was 83.7% in differentiating the benign from the malignant tumors (85.3% sensitivity, 81.2% specificity, 86.4% positive predictive value [PPV], and 79.5% negative predictive value [NPV]). The accuracy using DCE with Tpeak and TIC alone was 72.1% (69.1% sensitivity, 74.1% specificity, 77.5% PPV, and 65.1% NPV). Using DW-MRI parameter was superior than using DCE parameters in differentiation between benign and malignant sinonasal tumors (P < 0.001). The accuracy was 87.3% (90.5% sensitivity, 82.7% specificity, 88.2% PPV, and 85.9% NPV) using DW-MRI combined with DCE-MRI, which was superior than that using DCE-MRI alone or using DW-MRI alone (both P < 0.001) in differentiating the benign from the malignant tumors.

Conclusions:

Diffusion-weighted combined with DCE-MRI can improve imaging performance in differentiating benign from malignant sinonasal tumors, which has the potential to improve diagnostic accuracy and to provide added value in the management for these tumors.     

Insulin Neuroprotection and the Mechanisms

Objective:

To analyze the mechanism of neuroprotection of insulin and which blood glucose range was benefit for insulin exerting neuroprotective action.

Data Sources:

The study is based on the data from PubMed.

Study Selection:

Articles were selected with the search terms “insulin”, “blood glucose”, “neuroprotection”, “brain”, “glycogen”, “cerebral ischemia”, “neuronal necrosis”, “glutamate”, “γ-aminobutyric acid”.

Results:

Insulin has neuroprotection. The mechanisms include the regulation of neurotransmitter, promoting glycogen synthesis, and inhibition of neuronal necrosis and apoptosis. Insulin could play its role in neuroprotection by avoiding hypoglycemia and hyperglycemia.

Conclusions:

Intermittent and long-term infusion insulin may be a benefit for patients with ischemic brain damage at blood glucose 6–9 mmol/L.     

Intestinal Microbiota Metabolism and Atherosclerosis

Objective:

This review aimed to summarize the relationship between intestinal microbiota metabolism and cardiovascular disease (CVD) and to propose a novel CVD therapeutic target.

Data Sources:

This study was based on data obtained from PubMed and EMBASE up to June 30, 2015. Articles were selected using the following search terms: “Intestinal microbiota”, “trimethylamine N-oxide (TMAO)”, “trimethylamine (TMA)”, “cardiovascular”, and “atherosclerosis”.

Study Selection:

Studies were eligible if they present information on intestinal microbiota metabolism and atherosclerosis. Studies on TMA-containing nutrients were also included.

Results:

A new CVD risk factor, TMAO, was recently identified. It has been observed that several TMA-containing compounds may be catabolized by specific intestinal microbiota, resulting in TMA release. TMA is subsequently converted to TMAO in the liver. Several preliminary studies have linked TMAO to CVD, particularly atherosclerosis; however, the details of this relationship remain unclear.

Conclusions:

Intestinal microbiota metabolism is associated with atherosclerosis and may represent a promising therapeutic target with respect to CVD management.     

Plaques of Nonstenotic Basilar Arteries with Isolated Pontine Infarction on Three-dimensional High Isotropic Resolution Magnetic Resonance Imaging

Background:

There are few studies for evaluating plaque characteristics of nonstenotic basilar arteries (BA). Our aim was to determine entire BA plaques with a three-dimensional volumetric isotropic turbo spin-echo acquisition (VISTA) and investigate the differences between the patients with and without isolated pontine infarction (IPI).

Methods:

Twenty-four consecutive symptomatic patients with nonstenotic BA on time of flight magnetic resonance angiography (TOF MRA) were enrolled from China-Japan Friendship Hospital between January 2014 and December 2014. BA was classified as “normal” or “irregular” based on TOF MRA, and “normal wall”, “slight wall-thickening”, and “plaque” based on three-dimensional VISTA images. Outcomes from MRA and VISTA were compared. Patients were categorized as IPI and non-IPI groups based on the diffusion-weighted imaging. Clinical and plaque characteristics were compared between the two groups.

Results:

A total of 1024 image slices including 311 (30.37%) plaque slices, 427 (41.70%) slight wall-thickening slices, and 286 (27.93%) normal wall slices for the entire BA from 23 patients were finally included for analysis. VISTA images detected plaques in all the 9 (100%) irregular MRA patients and 7 of 14 (50%) normal MRA patients. IPI was found in 11 (47.83%) patients. Compared to non-IPI group, the IPI group had a higher percentage of plaque slices (P = 0.001) and lower percentage of normal wall slices (P = 0.014) than non-IPI group.

Conclusions:

Three-dimensional VISTA images enable detection of BA plaques not visualized by MRA. BA plaques could be found in both the IPI and non-IPI group. However, IPI group showed plaques more extensively in BA than the non-IPI group.     

Current and Future Clinical Applications of Zinc Transporter-8 in Type 1 Diabetes Mellitus

Objective:

To evaluate the utility of zinc transporter-8 (ZnT8) in the improvement of type 1 diabetes mellitus (T1DM) diagnosis and prediction, and to explore whether ZnT8 is a potential therapeutic target in T1DM.

Data Sources:

A search was conducted within the medical database PubMed for relevant articles published from 2001 to 2015. The search terms are as follows: “ZnT8,” “type 1 diabetes,” “latent autoimmune diabetes in adults,” “type 2 diabetes,” “islet autoantibodies,” “zinc supplement,” “T cells,” “β cell,” “immune therapy.” We also searched the reference lists of selected articles.

Study Selection:

English-language original articles and critical reviews concerning ZnT8 and the clinical applications of islet autoantibodies in diabetes were reviewed.

Results:

The basic function of ZnT8 is maintaining intracellular zinc homeostasis, which modulates the process of insulin biosynthesis, storage, and secretion. Autoantibodies against ZnT8 (ZnT8A) and ZnT8-specific T cells are the reliable biomarkers for the identification, stratification, and characterization of T1DM. Additionally, the results from the animal models and clinical trials have shown that ZnT8 is a diabetogenic antigen, suggesting the possibility of ZnT8-specific immunotherapy as an alternative for T1DM therapy.

Conclusions:

ZnT8 is a novel islet autoantigen with a widely potential for clinical applications in T1DM. However, before the large-scale clinical applications, there are still many problems to be solved.     

Cost-effectiveness Analysis for Technology Acquisition

Background

In a developing country with limited resources, it is important to utilize the total cost visibility approach over the entire life-cycle of the technology and then analyse alternative options for acquiring technology.

Methods

The present study analysed cost-effectiveness of an “In-house” magnetic resonance imaging (MRI) scan facility of a large service hospital against outsourcing possibilities. Cost per unit scan was calculated by operating costing method and break-even volume was calculated. Then life-cycle cost analysis was performed to enable total cost visibility of the MRI scan in both “In-house” and “outsourcing of facility” configuration. Finally, cost-effectiveness analysis was performed to identify the more acceptable decision option.

Result

Total cost for performing unit MRI scan was found to be Rs 3,875 for scans without contrast and Rs 4,129 with contrast. On life-cycle cost analysis, net present value (NPV) of the “In-house” configuration was found to be Rs-(4,09,06,265) while that of “outsourcing of facility” configuration was Rs-(5,70,23,315). Subsequently, cost-effectiveness analysis across eight Figures of Merit showed the “In-house” facility to be the more acceptable option for the system.

Conclusion

Every decision for acquiring high-end technology must be subjected to life-cycle cost analysis.Key Words: Technology assessment, Cost benefit analysis, Cost-effectiveness analysis     

Coronal Diffusion-weighted Magnetic Resonance Imaging of the Kidney: Agreement with Axial Diffusion-weighted Magnetic Imaging in Terms of Apparent Diffusion Coefficient Values

Background:

Coronal diffusion-weighted magnetic resonance imaging (DW-MRI) and apparent diffusion coefficient (ADC) values have gradually become applied (following conventional axial DW-MRI) in the renal analysis. To explore whether data obtained using coronal DW-MRI are comparable with those derived using axial DW-MRI, this preliminary study sought to assess the agreement in renal ADC values between coronal DW-MRI and axial DW-MRI.

Methods:

Thirty-four healthy volunteers were enrolled in the study; written consents were obtained. All subjects underwent respiratory-triggered axial and coronal DW-MRI using a 1.5-MR system with b values of 0 and 800 s/mm². The signal-to-noise ratios (SNRs) of the two DW-MRI sequences were measured and statistically compared using the paired t-test. The extent of agreement of ADC values of the upper pole, mid-pole, and lower pole of the kidney; the mean ADC values of the left kidney and right kidney; and the mean ADC values of the bilateral kidneys were evaluated via calculation of intraclass correlation coefficients (ICCs) or Bland–Altman method between the two DW-MRI sequences.

Results:

The SNR of coronal DW-MR images was statistically inferior to that of axial DW-MR images (P < 0.001). The ICCs of the ADC values of each region of interest, and the mean ADC values of bilateral kidneys, between the two sequences, were greater than 0.5, and the mean ADCs of the bilateral kidneys demonstrated the highest ICC (0.869; 95% confidence interval: 0.739–0.935). In addition, 94.1% (32/34), 94.1% (32/34), and 97.1% (31/34) of the ADC bias was inside the limits of agreement in terms of the mean ADC values of the left kidneys, right kidneys, and bilateral kidneys when coronal and axial DWI-MRI were compared.

Conclusions:

ADC values derived using coronal DW-MRI exhibited moderate-to-good agreement to those of axial DW-MRI, rendering the former an additional useful DW-MRI method, and causing the ADC values derived using the two types of DW-MRI to be comparable.     

Audit of an urban paediatric emergency department visits

Background:

This study aimed to highlight the health seeking behavior of children in an Emergency Department (ED).

Materials and Methods:

Retrospective files review of ED was done for the month of July, 2008. Data about the children ≤12 years of age was gathered.

Results:

In one month period a total 21000 patients visited our ED, out of them 6120 (29%) were children. Males, Saudis and children of (1-6 years) were more frequent, i.e., 3540 (57.8%), 5760 (94.1%) and 3180 (52%), respectively. Majority of patients visited in shift “2”, i.e., 15:30 hours to 23:30 hours. Among the patients “diseases of respiratory system” were found more frequent 4170 (68.1%) and main diagnosis was “acute upper respiratory tract infection” 3300 (53.9%). Non-urgent cases were 2020 (33%) while 244 (4%) were admitted.

Conclusion:

Young children as well as non-urgent cases were predominant. Evening shift was the busiest one.     

Contemporary approaches to managing atrial fibrillation: A survey of Australian general practitioners

Background

Recent attention to the management of atrial fibrillation (AF) and stroke prevention has emphasised the need to support the use of existing pharmacotherapy through available services and resources, in preference to using the new, more expensive, novel oral anticoagulants. In this regard, general practitioners (GPs) are at the core of care.

Aims

To survey Australian GPs regarding their approach to managing AF, particularly in relation to stroke prevention therapy, and to identify the range of services to support patient care.

Methods

A structured questionnaire, comprising quantitative and qualitative responses, was administered to participating GPs within four geographical regions of NSW (metropolitan, regional, rural areas).

Results

Fifty GPs (mean age 53.74±9.94 years) participated. Most (98 per cent) GPs regarded themselves as primarily responsible for the management of AF, only referring patients to specialists when needed. However, only 10 per cent of GPs specialised in “heart/vascular health”. Most (76 per cent) GPs offered point-of-care international normalised ratio (INR) testing, with 90 per cent also offering patient support via practice nurses and home visits. Overall, key determinants influencing GPs’ initiation of antithrombotic therapy were: “stroke risk”/”CHADS₂ score”, followed by “patients’ adherence/compliance”. GPs focused more on medication safety considerations and the day-to-day management of therapy than on the risk of bleeding.

Conclusion

Australian GPs are actively engaged in managing AF, and appear to be well resourced. Importantly, there is a greater focus on the benefits of therapy during decision-making, rather than on the risks. However, medication safety considerations affecting routine management of therapy remain key concerns, with patients’ adherence to therapy a major determinant in decision-making.     

Distribution of Major Pathogens from Sputum and Bronchoalveolar Lavage Fluid in Patients with Noncystic Fibrosis Bronchiectasis: A Systematic Review

Objective:

Noncystic fibrosis (non-CF) bronchiectasis remains as a common health problem in Asia. Pathogens’ distribution in airways of patients with non-CF bronchiectasis is important for doctors to make right decision.

Data Sources:

We performed this systematic review on the English language literatures from 1966 to July 2014, using various search terms included “pathogens” or “bacteria” or “microbiology” and “bronchiectasis” or “non-cystic fibrosis bronchiectasis” or “non-CF bronchiectasis” or “NCFB.”

Study Selection:

We included studies of patients with the confirmed non-CF bronchiectasis for which culture methods were required to sputum or bronchoalveolar lavage fluid (BALF). Weighted mean isolation rates for Haemophilus influenzae, Pseudomonas aeruginosa, Streptococcus pneumoniae, Stapylococcus aureus, Moxarella catarrhails were compared according to different methodology.

Results:

The total mean bacterial culture positive rates were 63%. For studies using sputum samples, the mean positive culture rates were 74%. For studies using BALF alone or BALF and sputum, it was 48%. The distributions of main bacterial strains were 29% for H. influenzae, 28% for P. aeruginosa, 11% for S. pneumoniae, 12% for S. aureus, and 8% for M. catarrhails with methodology of sputum. Meanwhile, the bacterial distributions were 37% for H. influenzae, 8% for P. aeruginosa, 14% for S. pneumoniae, 5% for S. aureus, and 10% for M. catarrhails with methodology of BALF alone or BALF and sputum. Analysis of the effect of different methodology on the isolation rates revealed some statistically significant differences.

Conclusions:

H. influenzae accounted for the highest percentage in different methodology. Our results suggested that the total positive culture rates and the proportion of P. aeruginosa from sputum and BALF specimens had significant differences, which can be used in further appropriate recommendations for the treatment of non-CF bronchiectasis.     

J Wave Syndromes: A Decade of Progress

Objective:

The objective was to provide a brief history of J wave syndromes and to summarize our current understanding of their molecular, ionic, cellular mechanisms, and clinical features. We will also discuss the existing debates and further direction in basic and clinical research for J wave syndromes.

Data Sources:

The publications on key words of “J wave syndromes”, “early repolarization syndrome (ERS)”, “Brugada syndrome (BrS)” and “ST-segment elevation myocardial infarction (STEMI)” were comprehensively reviewed through search of the PubMed literatures without restriction on the publication date.

Study Selection:

Original articles, reviews and other literatures concerning J wave syndromes, ERS, BrS and STEMI were selected.

Results:

J wave syndromes were firstly defined by Yan et al. in a Chinese journal a decade ago, which represent a spectrum of variable phenotypes characterized by appearance of prominent electrocardiographic J wave including ERS, BrS and ventricular fibrillation (VF) associated with hypothermia and acute STEMI. J wave syndromes can be inherited or acquired and are mechanistically linked to amplification of the transient outward current (I_to)-mediated J waves that can lead to phase 2 reentry capable of initiating VF.

Conclusions:

J wave syndromes are a group of newly highlighted clinical entities that share similar molecular, ionic and cellular mechanism and marked by amplified J wave on the electrocardiogram and a risk of VF. The clinical challenge ahead is to identify the patients with J wave syndromes who are at risk for sudden cardiac death and determine the alternative therapeutic strategies to reduce mortality.     

Asthma and Obstructive Sleep Apnea

Objective:

To get a comprehensive understanding about the relationship between obstructive sleep apnea (OSA) and asthma by reviewing the epidemiology, pathophysiology, and clinical manifestation and then summarizing the latest progress on diagnosis and treatment.

Data Sources:

Articles referred in this review were mainly collected from a comprehensive search of the PubMed published in English from 1990 to 2015 with the terms “OSA” and “asthma” as the main keywords. Highly regarded older publications were also included.

Study Selection:

Information about the features of the two diseases in common, the pathophysiologic association between them and their current treatments from the literature search were identified, retrieved, and summarized.

Results:

Both OSA and asthma are very prevalent conditions. The incidences of them have kept on rising in recent years. Asthma is often accompanied by snoring and apnea, and OSA often combines with asthma, as well. They have many predisposing and aggravating factors in common. Possible shared direct mechanistic links between them include mechanical effects, intermittent hypoxia, nerve reflex, inflammation, leptin, etc. Indirect mechanistic links include medication, nose diseases, smoking, obesity, and gastroesophageal reflux disease. Since OSA presents many similar features with nocturnal asthma, some scholars termed them as a sole syndrome – “alternative overlap syndrome,” and proved that asthma symptoms in those patients could be improved through the treatment of continuous positive airway pressure.

Conclusions:

OSA and asthma are closely associated in pathogenesis, symptoms, and therapies. With the growing awareness of the relationship between them, we should raise our vigilance on the coexistence of OSA in those difficult-to-control asthmatic patients. Further studies are still needed to guide the clinical works.     

Monitoring the Progression of Renal Fibrosis by T2-weighted Signal Intensity and Diffusion Weighted Magnetic Resonance Imaging in Cisplatin induced Rat Models

Background:

Diffusion weighted imaging (DWI), with the applying of intravoxel incoherent motion model, has showed promising results in obtaining additional information about microperfusion and tubular flow associated with morphologic changes in chronic kidney diseases. The study aims to evaluate the potential of T2-weighted signal intensity (SI) and DWI with mono- and bi-exponential models to reflect the serial changes on cisplatin (CP) induced rat renal fibrosis models.

Methods:

Magnetic resonance exams were performed prior to and 2^nd day, 4^th day, 6^th day, 8^th day, 2^nd week, 3^rd week and 4^th week after CP injection at a 3.0T with an animal coil. Besides T2-weighted images (T2WI), DWI of 13 b values from 0 to 1500 s/mm² was acquired. Apparent diffusion coefficient (ADC), fluid fraction f, pure diffusivity D and pseudodiffusivity D* values were calculated. The regions of interest were placed on cortex (CO), outer stripe of the outer medulla (OM) and inner stripe of the outer medulla (OM), parameters were measured and compared among different time points. Five rats were scarified at each time point for pathological examination.

Results:

OM revealed remarkable hyperintense and broadened before it became an obscure thread, while CO demonstrated moderate hyperintense and IM didn’t show significant change on T2WI. On all three stripes, ADC values decreased firstly then kept increasing since the 4^th day; f values decreased on all stripes; D values had a tendency to increase with fluctuations but the changes didn’t achieve statistical significance; D* values increased at the 2^nd day then tended to be steady thereafter. Pathological findings revealed tubules epitheliums swelling followed by inflammation cells infiltration, interstitial fibrosis was observed since the 2^nd week.

Conclusions:

All of T2-weighted SI, ADC, and biexponential models parameters vary during fibrotic process; biexponential model is superior to monoexponential model in separating changes of microperfusion together with tubular flow from pure diffusion.     

Quantitative Measurement of Cerebral Perfusion with Intravoxel Incoherent Motion in Acute Ischemia Stroke: Initial Clinical Experience

Background:

Intravoxel incoherent motion (IVIM) has the potential to provide both diffusion and perfusion information without an exogenous contrast agent, its application for the brain is promising, however, feasibility studies on this are relatively scarce. The aim of this study is to assess the feasibility of IVIM perfusion in patients with acute ischemic stroke (AIS).

Methods:

Patients with suspected AIS were examined by magnetic resonance imaging within 24 h of symptom onset. Fifteen patients (mean age was 68.7 ± 8.0 years) who underwent arterial spin labeling (ASL) and diffusion-weighted imaging (DWI) were identified as having AIS with ischemic penumbra were enrolled, where ischemic penumbra referred to the mismatch areas of ASL and DWI. Eleven different b-values were applied in the biexponential model. Regions of interest were selected in ischemic penumbras and contralateral normal brain regions. Fast apparent diffusion coefficients (ADCs) and ASL cerebral blood flow (CBF) were measured. The paired t-test was applied to compare ASL CBF, fast ADC, and slow ADC measurements between ischemic penumbras and contralateral normal brain regions. Linear regression and Pearson''s correlation were used to evaluate the correlations among quantitative results.

Results:

The fast ADCs and ASL CBFs of ischemic penumbras were significantly lower than those of the contralateral normal brain regions (1.93 ± 0.78 μm²/ms vs. 3.97 ± 2.49 μm²/ms, P = 0.007; 13.5 ± 4.5 ml·100 g^-1·min^-1 vs. 29.1 ± 12.7 ml·100 g^-1·min^-1, P < 0.001, respectively). No significant difference was observed in slow ADCs between ischemic penumbras and contralateral normal brain regions (0.203 ± 0.090 μm²/ms vs. 0.198 ± 0.100 αμm²/ms, P = 0.451). Compared with contralateral normal brain regions, both CBFs and fast ADCs decreased in ischemic penumbras while slow ADCs remained the same. A significant correlation was detected between fast ADCs and ASL CBFs (r = 0.416, P < 0.05). No statistically significant correlation was observed between ASL CBFs and slow ADCs, or between fast ADCs and slow ADCs (r = 0.111, P = 0.558; r = 0.200, P = 0.289, respectively).

Conclusions:

The decrease in cerebral blood perfusion primarily results in the decrease in fast ADC in ischemic penumbras; therefore, fast ADC can reflect the perfusion situation in cerebral tissues.     

Role of MicroRNAs in Malignant Glioma

Objective:

This overview seeked to bring together the microRNA (miRNA) researches on biogenesis and bio-function in these areas of clinical diagnosis and therapy for malignant glioma.

Data Sources:

Using the keyword terms “glioma” and “miRNA,” we performed the literature search in PubMed, Ovid, and web.metstr.com databases from their inception to October 2014.

Study Selection:

In screening out the quality of the articles, factors such as clinical setting of the study, the size of clinical samples were taken into consideration. Animal studied for verification and reviews article were also included in our data collection.

Results:

Despite many advance in miRNA for malignant glioma, further studies were still required to focus on the following aspects: (i) Improving the understanding about biogenesis of miRNA and up-down regulation; (ii) utilizing high-throughput miRNA expression analysis to screen out the core miRNA for glioma; (iii) Focusing related miRNAs on the signal transduction pathways that regulate the proliferation and growth of glioma.

Conclusions:

We discussed the most promising miRNA, correlative signaling pathway and their relation with gliomas in the way of prompting miRNA target into being a clinical therapeutic strategy.