Comparison of 99mTc-DMSA renal scintigraphy with biochemical and histopathological findings in animal models of acute kidney injury

Biochemical and histological assays are currently used for the diagnosis and characterization of kidney injury. The purpose of this study was to compare technetium- 99m-labeled dimercaptosuccinic acid (99mTc- DMSA) renal scintigraphy, as a non-invasive method, with common biochemical and histopathological methods in two animal models of acute kidney injury. Nephrotoxicity was induced either by gentamicin (100 mg/kg/day for one week) or unilateral ureteral ligation (UUO). Renal scintigraphy was performed 1 h after intravenous injection of 99mTc-DMSA (3 mCi). Furthermore, plasma levels of blood urea nitrogen (BUN), creatinine, sodium, and potassium were determined using an autoanalyzer. At the end of experiments, kidneys were excised for the measurement of activity uptake (mCi/gr) using a dose calibrator as well as histopathological examinations with hematoxylin and eosin (H&E) staining. There was a significant decrease in 99mTc-DMSA uptake in both gentamicin (P value = 0.049) and UUO (P value = 0.034) groups, and it was more significant in the former. The levels of BUN and creatinine increased in both gentamicin and UUO groups, while the levels of sodium and potassium remained unchanged. Furthermore, a strong correlation was found between DMSA uptake and histopathological findings. Scintigraphy with 99mTc-DMSA is capable of detection of kidney injury in both gentamicin and UUO groups. Moreover, a significant correlation was found between scintigraphy parameters and histopathological findings. This suggests 99mTc-DMSA as a non-invasive method for the evaluation of kidney injury induced by drugs or anatomical disorders

Environmental radioactivity studies in Kabul and northern Afghanistan

[no abstract

Assessment of the maximum uptake time of 99mTc-DMSA in renal scintigraphy in rat

Introduction: The optimal imaging time of a radionuclide scintigraphy is the time at which the organ of interest has the maximum uptake of the injected radionuclide. This study was performed to investigate the maximum uptake time of 99mTc-DMSA in rat renal scan. Methods: Renal scintigraphy was performed with 3 mCi of 99mTc-DMSA. Planar images were acquired every 20 minutes for 8 hours post-injection using a small-animal SPECT. Results: Activity and the count rate per pixel (CRPP) of the kidneys peaked 1 h post-injection, plateaued for about 1 h, and declined time-dependently. Kidney to background ratio (KBR) reached to 61.7% at 1 h after injection and remained almost constant afterwards. Conclusion: The kidneys had maximum emission and CRPP between 1 to 2 h after 99mTc-DMSA injection, whereas there was no significant difference between the KBRs after 1 h. Our results showed that image acquisition of 1-2 h post-injection is recommended for renal scintigraphy with DMSA in rat

Neural Correlates of Working Memory in Chronic Primary Insomnia using The Sternberg Task: A Preliminary Analysis

Chronic primary insomnia is characterized by difficulty falling sleep, maintaining sleep and waking up earlier than desired as well as daytime functioning impairment in the absence of an underlying neurological and psychological condition. Daytime functional impairment of patients with chronic primary insomnia is linked to cognitive deficits, including working memory. Functional neuroimaging studies investigating working memory in this population reported abnormal cerebral activation during cognitive abilities testing. This evidence could support altered cognitive functioning. Yet, the same results have not been replicated consistently. Hence, this study aims to provide more nuanced evidence by identifying a map of cerebral activation among patients with insomnia in different phases of working memory using the Sternberg task. This task has never been used for this population. The Sternberg task can evaluate the working memory ability for the encoding and recall phases of working memory separately. Based on our results, we observed that many brain regions that were activated in patients with insomnia were similar to those that were activated in good sleepers in response to a working memory task. Yet, there were key regions within the frontal cortex that were not activated. The differences were more noticeable in the recall phase. This needs to be quantitatively verified by including a control cohort and investigated whether potential working memory impairment in insomnia is phase dependant in future studies. We extended the literature by identifying phase-dependant and load-dependent regions of cerebral activation and deactivation in patients with chronic primary insomnia during the Sternberg task

Effects of intrathecal opioids use in cesarean section on breastfeeding and newborns’ weight gaining

Objective: To assess the association between intrapartum intrathecal opioid use and breastfeeding and weight gain following cesarean section. Materials and methods: The prospective double-blinded study was conducted on term pregnant women, undergoing elective cesarean section under spinal anesthesia. They divided into two groups. In the first group, intrathecal Morphine was used to achieve analgesia during or after the operation. The remainder divided into two subgroups, those who did not receive any opioid or those received systemic opioids. Following labor breastfeeding accessed in a follow-up, two month latter. Results: There was no difference between the demographic variables of the mothers and newborns APGAR score and weight at the time of birth. Breastfeeding rate was similar in intrathecal group in compare with other patents (P value = 0.518). While, the infants’ weight at the end of second month was lower in spinal opioid group (P value = 0.036). Conclusion: The present study was the first to suggest that spinal (intrathecal) opioids do not have any impact on breastfeeding. However the relationship between spinal anesthesia on weight gaining needs more investigation

Role of diffusion tensor imaging as an imaging biomarker and theranostic tool in structural imaging of traumatic brain injury

Neuroimaging technology is at a "newborn" stage in the evaluation of TBI. While additional literature are obviously required to decide whether these modalities and progress in knowledge with noninvasive monitors will allow early and consistent recognition of revocable secondary brain damages, the final query is whether these new modalities will help in treatment plans that will absolutely mark result. DTI is an influential instrument for assessing white matter anatomy and related anomalies. DTI was formerly an investigation tool, but is using clinical practice. Accepting the terms and basic ideas of this method can aid in the clinical implementation and interpretation of this blend of structural and physiologic white matter evaluation. In conclusion, although DTI is as a diagnostic tool for severity of TBI and as an outcome predictor, but severe preclinical and clinical validation of each imaging method should be a top importance

Implementation of absolute quantification in small-animal SPECT imaging: Phantom and animal studies

Purpose: Presence of photon attenuation severely challenges quantitative accuracy in single-photon emission computed tomography (SPECT) imaging. Subsequently, various attenuation correction methods have been developed to compensate for this degradation. The present study aims to implement an attenuation correction method and then to evaluate quantification accuracy of attenuation correction in small-animal SPECT imaging. Methods: Images were reconstructed using an iterative reconstruction method based on the maximum-likelihood expectation maximization (MLEM) algorithm including resolution recovery. This was implemented in our designed dedicated small-animal SPECT (HiReSPECT) system. For accurate quantification, the voxel values were converted to activity concentration via a calculated calibration factor. An attenuation correction algorithm was developed based on the first-order Chang’s method. Both phantom study and experimental measurements with four rats were used in order to validate the proposed method. Results: The phantom experiments showed that the error of �15.5% in the estimation of activity concentration in a uniform region was reduced to +5.1% when attenuation correction was applied. For in vivo studies, the average quantitative error of �22.8 � 6.3% (ranging from �31.2% to �14.8%) in the uncorrected images was reduced to +3.5 � 6.7% (ranging from �6.7 to +9.8%) after applying attenuation correction. Conclusion: The results indicate that the proposed attenuation correction algorithm based on the first-order Chang’s method, as implemented in our dedicated small-animal SPECT system, significantly improves accuracy of the quantitative analysis as well as the absolute quantification

The efficiency evaluation of mutual fund managers based on DARA, CARA, IARA

We evaluate the efficiency of mutual fund managers of 20 different classes of management styles to identify the most efficient strategies and to propose an optimal pattern in selecting the funds by investors. We collect monthly data of 17,686 US mutual funds for a five-year period 2005–2010 to minimize the impact of survivorship bias and use Data Envelopment Analysis (DEA) model to evaluate the mutual fund performance. The set of considered inputs comprised “variance”, representing the mutual fund risk, and “turnover, expense ratio and loads indicators”, reflecting the mutual fund costs and fees. Two kinds of outputs are taken into account by our DEA model, “portfolio return” and “stochastic dominance indicators”. As a unique contribution, we state the benefits of the DEA approach in the DARA, CARA, and IARA framework, and evaluate the efficiency of mutual funds based on fund strategies as well as the performance of best mutual funds among their group. The evidence shows that the efficiency scores of technical, management, and scale are respectively 0.81, 0.921, and 0.874 for the DARA model, while the efficiency scores of two models of CARA and IARA are negligible. Also, we rank each management strategy in any model based on two methods – the number of referencing and the weighted value so that the managers of inefficient strategies must pattern the managers’ ability of reference (efficient) strategies to improve their efficiency on the fund market in future

Implementation of absolute quantification in small-animal SPECT imaging: Phantom and animal studies

Purpose: Presence of photon attenuation severely challenges quantitative accuracy in single-photon emission computed tomography (SPECT) imaging. Subsequently, various attenuation correction methods have been developed to compensate for this degradation. The present study aims to implement an attenuation correction method and then to evaluate quantification accuracy of attenuation correction in small-animal SPECT imaging. Methods: Images were reconstructed using an iterative reconstruction method based on the maximum-likelihood expectation maximization (MLEM) algorithm including resolution recovery. This was implemented in our designed dedicated small-animal SPECT (HiReSPECT) system. For accurate quantification, the voxel values were converted to activity concentration via a calculated calibration factor. An attenuation correction algorithm was developed based on the first-order Chang’s method. Both phantom study and experimental measurements with four rats were used in order to validate the proposed method. Results: The phantom experiments showed that the error of �15.5% in the estimation of activity concentration in a uniform region was reduced to +5.1% when attenuation correction was applied. For in vivo studies, the average quantitative error of �22.8 � 6.3% (ranging from �31.2% to �14.8%) in the uncorrected images was reduced to +3.5 � 6.7% (ranging from �6.7 to +9.8%) after applying attenuation correction. Conclusion: The results indicate that the proposed attenuation correction algorithm based on the first-order Chang’s method, as implemented in our dedicated small-animal SPECT system, significantly improves accuracy of the quantitative analysis as well as the absolute quantification