Comparison of respiratory inductive plethysmography versus head-out plethysmography for anesthetized nonhuman primates in an animal biosafety level 4 facility

For inhalational studies and aerosol exposures to viruses, head-out plethysmography acquisition has been traditionally used for the determination of estimated inhaled dose in anesthetized nonhuman primates prior to or during an aerosol exposure. A pressure drop across a pneumotachograph is measured within a sealed chamber during inspiration/exhalation of the nonhuman primate, generating respiratory values and breathing frequencies. Due to the fluctuation of depth of anesthesia, pre-exposure respiratory values can be variable, leading to less precise and accurate dosing calculations downstream. Although an anesthesia infusion pump may help stabilize the depth of sedation, pumps are difficult to use within a sealed head-out plethysmography chamber. Real-time, head-out plethysmography acquisition could increase precision and accuracy of the measurements, but the bulky equipment needed for head-out plethysmography precludes real-time use inside a Class III biological safety cabinet, where most aerosol exposures occur. However, the respiratory inductive plethysmography (RIP) acquisition method measures the same respiratory parameters by detecting movement of the chest and abdomen during breathing using two elastic bands within the Class III biological safety cabinet. As respiratory values are relayed to a computer for software integration and analysis real-time, adjustment of aerosol exposure duration is based on the depth of sedation of the animal. The objective of this study was to compare values obtained using two methodologies (pre-exposure head-out plethysmography and real-time RIP). Transitioning to RIP technology with real-time acquisition provides more consistent, precise, and accurate aerosol dosing by reducing reported errors in respiratory values from anesthesia variability when using pre-exposure head-out plethysmography acquisition.     

SMS-based smartphone application for disease surveillance has doubled completeness and timeliness in a limited-resource setting – evaluation of a 15-week pilot program in Central African Republic (CAR)

Background

It is a challenge in low-resource settings to ensure the availability of complete, timely disease surveillance information. Smartphone applications (apps) have the potential to enhance surveillance data transmission.

Methods

The Central African Republic (CAR) Ministry of Health and Médecins Sans Frontières (MSF) conducted a 15-week pilot project to test a disease surveillance app, Argus, for 20 conditions in 21 health centers in Mambéré Kadéi district (MK 2016). Results were compared to the usual paper-based surveillance in MK the year prior (MK 2015) and simultaneously in an adjacent health district, Nana-Mambére (NM 2016). Wilcoxon rank sum and Kaplan-Meier analyses compared report completeness and timeliness; the cost of the app, and users’ perceptions of its usability were assessed.

Results

Two hundred seventy-one weekly reports sent by app identified 3403 cases and 63 deaths; 15 alerts identified 28 cases and 4 deaths. Median completeness (IQR) for MK 2016, 81% (81–86%), was significantly higher than in MK 2015 (31% (24–36%)), and NM 2016 (52% (48–57)) (p?<?0.01). Median timeliness (IQR) for MK 2016, 50% (39–57%) was also higher than in MK 2015, 19% (19–24%), and NM 2016 29% (24–36%) (p?<?0.01). Kaplan-Meier Survival Analysis showed a significant progressive reduction in the time taken to transmit reports over the 15-week period (p?<?0.01). Users ranked the app’s usability as greater than 4/5 on all dimensions. The total cost of the 15-week pilot project was US$40,575. It is estimated that to maintain the app in the 21 health facilities of MK will cost approximately US$18,800 in communication fees per year.

Conclusions

The app-based data transmission system more than doubled the completeness and timeliness of disease surveillance reports. This simple, low-cost intervention may permit the early detection of disease outbreaks in similar low-resource settings elsewhere.

     

Validation of MRI biomarkers of hepatic steatosis in the presence of iron overload in the ob/ob mouse

Purpose:

To validate the utility and performance of a T correction method for hepatic fat quantification in an animal model of both steatosis and iron overload.

Materials and Methods:

Mice with low (n = 6), medium (n = 6), and high (n = 8) levels of steatosis were sedated and imaged using a chemical shift‐based fat‐water separation method to obtain magnetic resonance imaging (MRI) fat‐fraction measurements. Imaging was performed before and after each of two superparamagnetic iron oxide (SPIO) injections to create hepatic iron overload. Fat‐fraction maps were reconstructed with and without T correction. Fat‐fraction with and without T correction and T measurements were compared after each injection. Liver tissue was harvested and imaging results were compared to triglyceride extraction and histology grading.

Results:

Excellent correlation was seen between MRI fat‐fraction and tissue‐based fat quantification. Injections of SPIOs led to increases in R (=1/T). Measured fat‐fraction was unaffected by the presence of iron when T correction was used, whereas measured fat‐fraction dramatically increased without T correction.

Conclusion:

Hepatic fat‐fraction measured using a T‐corrected chemical shift‐based fat‐water separation method was validated in an animal model of steatosis and iron overload. T correction enables robust fat‐fraction estimation in both the presence and absence of iron, and is necessary for accurate hepatic fat quantification. J. Magn. Reson. Imaging 2012;35:844–851. © 2011 Wiley Periodicals, Inc.     

Gadoxetic acid-enhanced T1-weighted MR cholangiography in primary sclerosing cholangitis

Purpose:

To investigate the value of gadoxetic acid‐enhanced three‐dimensional T1‐weighted MR cholangiography (T1w‐MRC) in comparison to three‐dimensional T2‐weighted MR cholangiopancreaticography (T2w‐MRCP) in patients with primary sclerosing cholangitis (PSC).

Materials and Methods:

Thirty‐four MR exams in 29 patients (46.0 ± 16.1 years; 19 men, 10 women) scanned within a 14‐month period were retrospectively included. Two abdominal radiologists independently evaluated image quality regarding image contrast, image quality degradation due to artifacts, and visualization quality of ducts. The order of biliary tree branches that were visualized and reader preference toward each method were recorded. Helpfulness of T1w‐MRC was scored in consensus. Confirmatory endoscopic retrograde cholangiopancreaticography (ERCP) performed within 3 months of the MR examination was available in 8 patients.

Results:

Image quality of T1w‐MRC and T2w‐MRCP was graded good to excellent in all cases. There were advantages for both T1w‐MRC (functional information, less degradation due to artifacts) and T2w‐MRCP (higher order of visualized branches, better branch depiction). Both readers showed preference for T2w‐MRCP; however, both readers found gadoxetic acid–enhanced T1w‐MRC helpful in the majority of cases.

Conclusion:

Gadoxetic acid‐enhanced T1w‐MRC is complementary to, but should not replace, T2w‐MRCP. T1w‐MRC is a useful adjunct to T2w‐MRCP for morphologic evaluation and provides additional diagnostic information. J. Magn. Reson. Imaging 2012;36:632–640. © 2012 Wiley Periodicals, Inc.     

Water-silicone separated volumetric MR acquisition for rapid assessment of breast implants

Purpose:

To develop a robust T₂‐weighted volumetric imaging technique with uniform water‐silicone separation and simultaneous fat suppression for rapid assessment of breast implants in a single acquisition.

Materials and Methods:

A three‐dimensional (3D) fast spin echo sequence that uses variable refocusing flip angles was combined with a three‐point chemical‐shift technique (IDEAL) and short tau inversion recovery (STIR). Phase shifts of ?π/6, +π/2, and +7π/6 between water and silicone were used for IDEAL processing. For comparison, two‐dimensional images using 2D‐FSE‐IDEAL with STIR were also acquired in axial, coronal, and sagittal orientations.

Results:

Near‐isotropic (true spatial resolution—0.9 × 1.3 × 2.0 mm³) volumetric breast images with uniform water‐silicone separation and simultaneous fat suppression were acquired successfully in clinically feasible scan times (7:00–10:00 min). The 2D images were acquired with the same in‐plane resolution (0.9 × 1.3 mm²), but the slice thickness was increased to 6 mm with a slice gap of 1 mm for complete coverage of the implants in a reasonable scan time, which varied between 18:00 and 22:30 min.

Conclusion:

The single volumetric acquisition with uniform water and silicone separation enables images to be reformatted into any orientation. This allows comprehensive assessment of breast implant integrity in less than 10 min of total examination time. J. Magn. Reson. Imaging 2012;35:1216‐1221. © 2012 Wiley Periodicals, Inc.

     

Evaluation of acute chest pain syndromes by two-dimensional echocardiography: its potential application in the selection of patients for acute reperfusion therapy

Two-dimensional echocardiography is useful for the immediate diagnosis of acute myocardial infarction when diagnostic electrocardiographic changes are absent. The technique is also helpful in distinguishing myocardial infarction from other conditions that may clinically or electrocardiographically mimic infarction. The extent of myocardial infarction can be estimated by the two-dimensional echocardiographically derived wall motion score index. Therefore, two-dimensional echocardiography seems to be ideally suited for the initial noninvasive assessment of patients with acute chest pain syndromes, especially those who are considered for acute reperfusion therapy.