The dual roles of dissimilatory iron reduction in the carbon cycle: The "iron mesh" effect can increase inorganic carbon sequestration

Dissimilatory iron reduction (DIR) can drive the release of organic carbon (OC) as carbon dioxide (CO2 ) by mediating electron transfer between organic compounds and microbes. However, DIR is also crucial for carbon sequestration, which can affect inorganic-carbon redistribution via iron abiotic-phase transformation. The formation conditions of modern carbonate-bearing iron minerals (ICFe ) and their potential as a CO2 sink are still unclear. A natural environment with modern ICFe , such as karst lake sediment, could be a good analog to explore the regulation of microbial iron reduction and sequential mineral formation. We find that high porosity is conducive to electron transport and dissimilatory iron-reducing bacteria activity, which can increase the iron reduction rate. The iron-rich environment with high calcium and OC can form a large sediment pore structure to support rapid DIR, which is conducive to the formation and growth of ICFe . Our results further demonstrate that the minimum DIR threshold suitable for ICFe formation is 6.65 μmol g-1  dw day-1 . DIR is the dominant pathway (average 66.93%) of organic anaerobic mineralization, and the abiotic-phase transformation of Fe2+ reduces CO2 emissions by ~41.79%. Our findings indicate that as part of the carbon cycle, DIR not only drives mineralization reactions but also traps carbon, increasing the stability of carbon sinks. Considering the wide geographic distribution of DIR and ICFe , our findings suggest that the "iron mesh" effect may become an increasingly important vector of carbon sequestration.

Technical Note: Novel imaging method to obtain gray matter-attenuated inversion recovery image using low-field magnetic resonance imaging systems

INTRODUCTION

The double inversion recovery (DIR) technique suppresses two types of tissue signals with different T1 values by applying two inversion recovery (IR) pulses with different inversion times (TI). In contrast, the double tissue suppression with multi-echo acquisition and single TI combining HIRE (DOMUST-HIRE) method, is a technique enabling the white-matter-attenuated inversion recovery (WAIR) images by setting one inversion time (TI) in a sequence based on the multi-echo method and subtracting the second echo image from the first echo image. Here, we propose a new sequence that can provide the gray-matter-attenuated inversion recovery image based on the DOMUST-HIRE method.

METHODS

In this small clinical study, we performed determination of optimal TI and physical evaluation by imaging a subject's head with T1WI and our proposed method for GAIR images.

RESULTS

Our proposed method could increase the contrast ratio and the contrast-to-noise ratio between white matter (WM) and gray matter (GM), whereas the signal-to-noise ratio WM and GM decreased than with T1WI method.

CONCLUSIONS

Our proposed method can be used to suppress GM and CSF signals.

IMPLICATIONS FOR PRACTICE

The use of our proposed method in low-field MRI systems could provide GAIR image.

Patterns of failure for recurrent head and neck squamous cell carcinoma treated with salvage surgery and postoperative IMRT reirradiation

Purpose/Objectives

The purpose of this study was to evaluate patterns of locoregional recurrence (LRR) after surgical salvage and adjuvant reirradiation with IMRT for recurrent head and neck squamous cell cancer (HNSCC).

Materials/Methods

Patterns of LRR for 61 patients treated consecutively between 2003 and 2014 who received post-operative IMRT reirradiation to ≥ 60 Gy for recurrent HNSCC were determined by 2 methods: 1) physician classification via visual comparison of post-radiotherapy imaging to reirradiation plans; and 2) using deformable image registration (DIR). Those without evaluable CT planning image data were excluded. All recurrences were verified by biopsy or radiological progression. Failures were defined as in-field, marginal, or out-of-field. Logistic regression analyses were performed to identify predictors for LRR.

Results

A total of 55 patients were eligible for analysis and 23 (42 %) had documented LRR after reirradiation. Location of recurrent disease prior to salvage surgery (lymphatic vs. mucosal) was the most significant predictor of LRR after post-operative reirradiation with salvage rate of 67 % for lymphatic vs. 33 % for mucosal sites (p = 0.037). Physician classification of LRR yielded 14 (61 %) in-field failures, 3 (13 %) marginal failures, and 6 (26 %) out-of-field failures, while DIR yielded 10 (44 %) in-field failures, 4 (17 %) marginal failures, and 9 (39 %) out-of-field failures. Most failures (57 %) occurred within the original site of recurrence or first echelon lymphatic drainage. Of patients who had a free flap placed during salvage surgery, 56 % of failures occurred within 1 cm of the surgical flap.

Conclusion

Our study highlights the role of DIR in enhancing the accuracy and consistency of POF analysis. Compared to traditional visual inspection, DIR reduces interobserver variability and provides more nuanced insights into dose-specific and spatial parameters of locoregional recurrences. Additionally, the study identifies the location of the initial recurrence as a key predictor of subsequent locoregional recurrence after salvage surgery and re-IMRT.

Cortical ischemic lesions from atrial myxoma as a mimic of disease activity in an RRMS antiCD20-treated patient

Cortical lesions (CLs) detected with double inversion recovery (DIR) magnetic resonance imaging (MRI) are very helpful in differentiating multiple sclerosis (MS) from other neuroinflammatory diseases of the central nervous system (CNS), that is, neuromyelitis optica spectrum disorders (NMOSDs). Furthermore, CLs are closely related to motor and cognitive impairment. We report a case of a 48-year-old female MS patient who developed several CLs during anti-CD20 therapy. Some CLs disappeared during follow-up MRIs. In the suspicion of a treatment failure, the screening for the autologous hematopoietic stem cell transplant (AHSCT) was performed with the evidence of an atrial myxoma. In MS patients with new CLs, a comorbid ischemic pathology should be considered and carefully investigated.

Genome-wide identification, characterization, evolution and expression analysis of the DIR gene family in potato (Solanum tuberosum)

The dirigent (DIR) gene is a key player in environmental stress response and has been identified in many multidimensional tube plant species. However, there are few studies on the StDIR gene in potato. In this study, we used genome-wide identification to identify 31 StDIR genes in potato. Among the 12 potato chromosomes, the StDIR gene was distributed on 11 chromosomes, among which the third chromosome did not have a family member, while the tenth chromosome had the most members with 11 members. 22 of the 31 StDIRs had a classical DIR gene structure, with one exon and no intron. The conserved DIR domain accounts for most of the proteins in the 27 StDIRs. The structure of the StDIR gene was analyzed and ten different motifs were detected. The StDIR gene was divided into three groups according to its phylogenetic relationship, and 22 duplicate genes were identified. In addition, four kinds of cis-acting elements were detected in all 31 StDIR promoter regions, most of which were associated with biotic and abiotic stress. The findings demonstrated that the StDIR gene exhibited specific responses to cold stress, salt stress, ABA, and drought stress. This study provides new candidate genes for improving potato's resistance to stress.

Evaluating synthetic computed tomography images for adaptive radiotherapy decision making in head and neck cancer

Background and purpose

Adaptive radiotherapy (ART) decision-making benefits from dosimetric information to supplement image inspection when assessing the significance of anatomical changes. This study evaluated a dosimetry-based clinical decision workflow for ART utilizing deformable registration of the original planning computed tomography (CT) image to the daily Cone Beam CT (CBCT) to replace the need for a replan CT for dose estimation.

Materials and methods

We used 12 retrospective Head & Neck patient cases having a ground truth - a replan CT (rCT) in response to anatomical changes apparent in the daily CBCT - to evaluate the accuracy of dosimetric assessment conducted on synthetic CTs (sCT) generated by deforming the original planning CT Hounsfield Units to the daily CBCT anatomy.The original plan was applied to the sCT and dosimetric accuracy of the sCT was assessed by analyzing plan objectives for targets and organs-at-risk compared to calculations on the ground-truth rCT. Three commercial DIR algorithms were compared.

Results

For the best-performing algorithms, the majority of dose metrics calculated on the sCTs differed by less than 4 Gy (5.7% of 70 Gy prescription dose). An uncertainty of ±2.5 Gy (3.6% of 70 Gy prescription) is recommended as a conservative tolerance when evaluating dose metrics on sCTs for head and neck.

Conclusions

Synthetic CTs present a valuable addition to the adaptive radiotherapy workflow, and synthetic CT dose estimates can be effectively used in addition to the current practice of visually inspecting the overlay of the planning CT and CBCT to assess the significance of anatomical change.

Inter- and intrafractional 4D dose accumulation for evaluating ΔNTCP robustness in lung cancer

BACKGROUND AND PURPOSE

Model-based selection of proton therapy patients relies on a predefined reduction in normal tissue complication probability (NTCP) with respect to photon therapy. The decision is necessarily made based on the treatment plan, but NTCP can be affected when the delivered treatment deviates from the plan due to delivery inaccuracies. Especially for proton therapy of lung cancer, this can be important because of tissue density changes and, with pencil beam scanning, the interplay effect between the proton beam and breathing motion.

MATERIALS AND METHODS

In this work, we verified whether the expected benefit of proton therapy is retained despite delivery inaccuracies by reconstructing the delivered treatment using log-file based dose reconstruction and inter- and intrafractional accumulation. Additionally, the importance of two uncertain parameters for treatment reconstruction, namely deformable image registration (DIR) algorithm and α/β ratio, was assessed.

RESULTS

The expected benefit or proton therapy was confirmed in 97% of all studied cases, despite regular differences up to 2 percent point (p.p.) NTCP between the delivered and planned treatments. The choice of DIR algorithm affected NTCP up to 1.6 p.p., an order of magnitude higher than the effect of α/β ratio.

CONCLUSION

For the patient population and treatment technique employed, the predicted clinical benefit for patients selected for proton therapy was confirmed for 97.0% percent of all cases, although the NTCP based proton selection was subject to 2 p.p. variations due to delivery inaccuracies.

[Research progress in DIR gene of lignan biosynthesis in medicinal plants]

The active components, mainly derived from secondary metabolites of medicinal plants, are the material basis for the efficacy of medicinal plants. Lignans, the secondary metabolites in plants with high bioactivity, are widely distributed in a variety of plant species, and their antiviral, antitumor, antibacterial, and antioxidant activities have been proved in clinical practice. Generally, lignans are diverse in structures with many chiral centers, and most of them are optically active. The biosynthesis of lignans depends on the oxidative coupling reaction through site selection and stereo selection, which impedes synthesized lignans to form racemates, but makes them in a three-dimensional configuration. Dirigent protein(DIR) plays an important role in guiding location selection and stereo selection of lignans in biosynthesis. In vitro studies on lignan biosynthesis have shown that racemic end products are obtained in the absence of DIR proteins, while the products in a three-dimensional configuration can be yielded in the presence of DIR proteins, indicating that DIR proteins play an asymmetric role in the biosynthesis of plant secondary metabolites. The present study reviewed the biolo-gical significance of DIR protein, the cloning of DIR gene, gene structure, catalytic mechanism, and the research progress in Isatis indigotica, Eucommia ulmoides, Forsythia suspensa, Salvia miltiorrhiza, Panax pseudoginseng var. notoginseng, and Schisandra chinensis, which provides a reference for the follow-up research of DIR gene.

Image Exchange in Canada: Examples from the Province of Ontario

An increased number of healthcare providers across the continuum of care share responsibility for providing treatment and care to the patient. Treatment is often provided at community-based facilities and not necessarily at the hospital that performed the imaging. As a result, there is an increased dependency on readily available access to a patient’s longitudinal imaging records. The ways in which diagnostic images and results are exchanged among providers within a patient’s circle of care have expanded. This article explores three varieties of image exchange. First, we examine image exchange patterns within a regional Diagnostic Imaging Repository and identify missed sharing opportunities. Secondly, we explore the use of a regional clinical viewer widely used in southwestern Ontario, called ClinicalConnect™, and examine the adoption of the viewer by providers. Finally, the paper provides a high-level look at how patients can leverage patient portals to view their imaging data to empower their healthcare experience.

Evaluation of the relationship between the range of radiation-induced lung injury on CT images after IMRT for stage I lung cancer and dosimetric parameters

BACKGROUND

This study evaluated the correlation between radiation-induced lung injury (RILI) and dosimetric parameters on computed tomography (CT) images of stage I non-small cell lung cancer (NSCLC) patients undergoing intensity-modulated radiotherapy (IMRT).

MATERIALS AND METHODS

Sixty-three stage I NSLC patients who underwent IMRT were enrolled in the study. The patients underwent CT within 6 months (acute phase) and 1.5 years (late phase) after radiotherapy. These were fused with the planned irradiation CT. The range of RILI was measured from 10% to 100%, with an IC in 10% increments.

RESULTS

The median interval from completion of radiotherapy to acute and late phase CT was 92 and 440 days, respectively. The median RILI ranges of the acute and late phases were in the 80% (20-100%) and 70% dose regions (20-100%), respectively. The significantly narrower range of RILI when lung V20 in the acute phase was less than 19.2% and that of V5 in the late phase was less than 27.6% at the time of treatment planning.

CONCLUSIONS

This study showed that RILI occurred in a localized range in stage I NSCLC patients who underwent IMRT. The range of RILI was correlated with V20 in the acute phase and V5 in the late phase. KEY MESSAGES RILI correlated with V20 in acute and V5 in late phase. The shadow of RILI occurred in 80% dose region in acute and 70% in late phase. No relationship exists between radiographic changes in RILI and PTV volume.

Deformable image registration to assist clinical decision for radiotherapy treatment adaptation for head and neck cancer patients

Head and neck (H&N) cancer patients often present anatomical and geometrical changes in tumors and organs at risk (OARs) during radiotherapy treatment. These changes may result in the need to adapt the existing treatment planning, using an expert's subjective opinion, for offline adaptive radiotherapy and a new treatment planning before each treatment, for online adaptive radiotherapy. In the present study, a fast methodology is proposed to assist in planning adaptation clinical decision using tumor and parotid glands percentage volume changes during treatment. The proposed approach was applied to 40 Η&Ν cases, with one planning Computed Tomography (pCT) image and CBCT scans for 6 weeks of treatment per case. Deformable registration was used for each patient's pCT image alignment to its weekly CBCT. The calculated transformations were used to align each patient's anatomical structures to the weekly anatomy. Clinical target volume (CTV) and parotid gland volume percentage changes were calculated in each case. The accuracy of the achieved image alignment was validated qualitatively and quantitatively. Furthermore, statistical analysis was performed to test if there is a statistically significant correlation between CTV and parotid glands volume percentage changes. Average MDA for CTV and parotid glands between corresponding structures defined by an expert in CBCTs and automatically calculated through registration was 1.4 ± 0.1 mm and 1.5 ± 0.1 mm, respectively. The mean registration time of the first CBCT image registration for 40 cases was lower than 3.4 min. Five patients show more than 20% tumor volume change. Six patients show more than 30% parotid glands volume change. Ten out of 40 patients proposed for planning adaptation. All the statistical tests performed showed no correlation between CTV/parotid glands percentage volume changes. The aim to assist in clinical decision making on a fast and automatic way was achieved using the proposed methodology, thereby reducing workload in clinical practice.

The Prognostic Value of White-Matter Selective Double Inversion Recovery MRI Sequence in Multiple Sclerosis: An Exploratory Study

Using a white-matter selective double inversion recovery sequence (WM-DIR) that suppresses both grey matter (GM) and cerebrospinal fluid (CSF) signals, some white matter (WM) lesions appear surrounded by a dark rim. These dark rim lesions (DRLs) seem to be specific for multiple sclerosis (MS). They could be of great usefulness in clinical practice, proving to increase the MRI diagnostic criteria specificity. The aims of this study are the identification of DRLs on 1.5 T MRI, the exploration of the relationship between DRLs and disease course, the characterization of DRLs with respect to perilesional normal-appearing WM using magnetization transfer imaging, and the investigation of possible differences in the underlying tissue properties by assessing WM-DIR images obtained at 3.0 T MRI. DRLs are frequent in primary progressive MS (PPMS) patients. Amongst relapsing-remitting MS (RRMS) patients, DRLs are associated with a high risk of the disease worsening and secondary progressive MS (SPMS) conversion after 15 years. The mean magnetization transfer ratio (MTR) of DRLs is significantly different from the lesion without the dark rim, suggesting that DRLs correspond to more destructive lesions.

Investigation of 4D dose in volumetric modulated arc therapy-based stereotactic body radiation therapy: does fractional dose or number of arcs matter?

The aim of this study was to assess the impact of fractional dose and the number of arcs on interplay effects when volumetric modulated arc therapy (VMAT) is used to treat lung tumors with large respiratory motions. A three (fractional dose of 4, 7.5 or 12.5 Gy) by two (number of arcs, one or two) VMAT plan was created for 10 lung cancer cases. The median 3D tumor motion was 17.9 mm (range: 8.2-27.2 mm). Ten phase-specific subplans were generated by calculating the dose on each respiratory phase computed tomography (CT) scan using temporally assigned VMAT arcs. We performed temporal assignment of VMAT arcs using respiratory information obtained from infrared markers placed on the abdomens of the patients during CT simulations. Each phase-specific dose distribution was deformed onto exhale phase CT scans using contour-based deformable image registration, and a 4D plan was created by dose accumulation. The gross tumor volume dose of each 4D plan (4D GTV dose) was compared with the internal target volume dose of the original plan (3D ITV dose). The near-minimum 4D GTV dose (D99%) was higher than the near-minimum 3D internal target volume (ITV) dose, whereas the near-maximum 4D GTV dose (D1%) was lower than the near-maximum 3D ITV dose. However, the difference was negligible, and thus the 4D GTV dose corresponded well with the 3D ITV dose, regardless of the fractional dose and number of arcs. Therefore, interplay effects were negligible in VMAT-based stereotactic body radiation therapy for lung tumors with large respiratory motions.

Voxel-based morphometry analysis of double inversion-recovery magnetic resonance imaging for detecting microscopic lesions: a simulation study

Double inversion-recovery (DIR) imaging has the potential to improve the detection of subcortical lesions through the use of voxel-based morphometry (VBM) analysis. The aim of this study was to clarify the characteristics of detectable lesions by performing a VBM analysis on DIR images of simulated lesions. Twenty healthy volunteers underwent magnetic resonance imaging using a head three-dimensional DIR sequence. The images were processed using SPM12; then, the selected images with simulated lesions were analyzed via VBM. The VBM results were evaluated using free-response receiver-operating characteristic curves and a receiver-operating characteristic analysis. The sensitivity was 100% (5/5), with 5.6 false-positive objects per case, in simulated lesions with a contrast of 0.6 and a size of 2.4 mm. The sensitivity was 80% (4/5), with 5.4 false-positive objects per case, in simulated lesions with a contrast of 0.5 and a size of 2.4 mm. The mean area under the curve value was increased from 0.783 to 0.883 using VBM, with a statistically significant difference (p < 0.01). The VBM analysis of the DIR images using SPM alone showed the potential to detect subcortical microscopic lesions. Early detection of Alzheimer's disease may be possible by adapting VBM in the clinical setting.

Factors associated with parent engagement in DIR/Floortime for treatment of children with autism spectrum disorder

Background

The Developmental, Individual-differences, Relationship-based model (DIR/Floortime) is one of the well-known therapies for autism spectrum disorder (ASD), in which its main principle is to promote holistic development of an individual and relationships between the caregivers and children. Parental engagement is an essential element to DIR/Floortime treatment and involved with various factors. Finding those supporting factors and eliminating factors that might be an obstacle for parental engagement are essential for children with ASD to receive the full benefits of treatment.

Aim

To examine the association between parents, children and provider and service factors with parental engagement in DIR/Floortime treatment.

Methods

This is a cross-sectional study of parents with children aged 2–12 years who were diagnosed with ASD. Data were collected using a parent, child, provider and service factors questionnaire. Patient Health Questionaire-9, Clinical Global Impressions-Severity and Childhood Autism Rating Scale were also used to collect data. For parent engagement in DIR/Floortime, we evaluated quality of parental engagement in DIR/Floortime and parent application of DIR/Floortime techniques at home. Finally, Clinical Global Impressions-Improvement and Functional Emotional Developmental Level were used to assess child development.

Results

Parents who were married, had lower income and higher knowledge of DIR/Floortime theory were more likely to have higher parent engagement (χ²=4.43, p=0.035; χ²=13.1, p<0.001 and χ²=4.06, p=0.044 respectively). Furthermore, severity of the diagnosis and the continuation of the treatment significantly correlated with parent engagement (χ²=5.83, p=0.016  and χ²=4.72, p=0.030 respectively). It was found that parents who applied the techniques for more than 1  hour/day, or had a high-quality parent engagement, significantly correlated with better improvement in child development (t=−2.03, p=0.049; t=−2.00, p=0.053, respectively).

Conclusion

Factors associated with parents, children, and provider and service factors had a significant correlation with parent engagement in DIR/Floortime in which children whose parents had more engagement in DIR/Floortime techniques had better improvement in child development.

Short T2 imaging using a 3D double adiabatic inversion recovery prepared ultrashort echo time cones (3D DIR-UTE-Cones) sequence

PURPOSE

To investigate high contrast imaging of short T2 tissues with a three-dimensional double adiabatic inversion recovery prepared ultrashort echo time Cones (3D DIR-UTE-Cones) sequence.

METHODS

The sequence used two sequential adiabatic inversion pulses to suppress signals from long T2 tissues, followed by multispoke UTE acquisition to detect signals from short T2 tissues. The two adiabatic inversion pulses are identical with a center frequency located at the water peak, but the spectral width is broad enough to cover both water and fat frequencies. The feasibility of this technique was demonstrated through numerical simulation and phantom studies. Finally, DIR-UTE-Cones was applied to three healthy volunteers to image cortical bone, patellar tendon, and Achilles tendon. T2* was also measured via single-component exponential fitting.

RESULTS

Numerical simulation suggests that the DIR technique provides perfect nulling of muscle and fat as well as efficient suppression of other long T2 tissues with T1 values between fat and water or those above water. Excellent image contrast can be achieved with DIR-UTE-Cones for the short T2 tissues, with fitted T2* values of 0.28-0.38 ms for cortical bone, 0.56 ± 0.07 ms for the patella tendon, and 0.45 ± 0.06 ms for the Achilles tendon, respectively.

CONCLUSION

The 3D DIR-UTE-Cones sequence provides robust suppression of long T2 tissues and allows selective imaging as well as T2* measurement of short T2 tissues such as cortical bone, patellar tendon, and the Achilles tendon. Magn Reson Med 79:2555-2563, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Patient-specific calibration of cone-beam computed tomography data sets for radiotherapy dose calculations and treatment plan assessment

Purpose

In this work, we propose a new method of calibrating cone beam computed tomography (CBCT) data sets for radiotherapy dose calculation and plan assessment. The motivation for this patient‐specific calibration (PSC) method is to develop an efficient, robust, and accurate CBCT calibration process that is less susceptible to deformable image registration (DIR) errors.

Methods

Instead of mapping the CT numbers voxel‐by‐voxel with traditional DIR calibration methods, the PSC methods generates correlation plots between deformably registered planning CT and CBCT voxel values, for each image slice. A linear calibration curve specific to each slice is then obtained by least‐squares fitting, and applied to the CBCT slice's voxel values. This allows each CBCT slice to be corrected using DIR without altering the patient geometry through regional DIR errors.

A retrospective study was performed on 15 head‐and‐neck cancer patients, each having routine CBCTs and a middle‐of‐treatment re‐planning CT (reCT). The original treatment plan was re‐calculated on the patient's reCT image set (serving as the gold standard) as well as the image sets produced by voxel‐to‐voxel DIR, density‐overriding, and the new PSC calibration methods. Dose accuracy of each calibration method was compared to the reference reCT data set using common dose‐volume metrics and 3D gamma analysis. A phantom study was also performed to assess the accuracy of the DIR and PSC CBCT calibration methods compared with planning CT.

Results

Compared with the gold standard using reCT, the average dose metric differences were ≤ 1.1% for all three methods (PSC: −0.3%; DIR: −0.7%; density‐override: −1.1%). The average gamma pass rates with thresholds 3%, 3 mm were also similar among the three techniques (PSC: 95.0%; DIR: 96.1%; density‐override: 94.4%).

Conclusions

An automated patient‐specific calibration method was developed which yielded strong dosimetric agreement with the results obtained using a re‐planning CT for head‐and‐neck patients.

SAR and scan-time optimized 3D whole-brain double inversion recovery imaging at 7T

PURPOSE

The aim of this project was to implement an ultra-high field (UHF) optimized double inversion recovery (DIR) sequence for gray matter (GM) imaging, enabling whole brain coverage in short acquisition times ( ≈5 min, image resolution 1 mm³ ).

METHODS

A 3D variable flip angle DIR turbo spin echo (TSE) sequence was optimized for UHF application. We implemented an improved, fast, and specific absorption rate (SAR) efficient TSE imaging module, utilizing improved reordering. The DIR preparation was tailored to UHF application. Additionally, fat artifacts were minimized by employing water excitation instead of fat saturation.

RESULTS

GM images, covering the whole brain, were acquired in 7 min scan time at 1 mm isotropic resolution. SAR issues were overcome by using a dedicated flip angle calculation considering SAR and SNR efficiency. Furthermore, UHF related artifacts were minimized.

CONCLUSION

The suggested sequence is suitable to generate GM images with whole-brain coverage at UHF. Due to the short total acquisition times and overall robustness, this approach can potentially enable DIR application in a routine setting and enhance lesion detection in neurological diseases. Magn Reson Med 79:2620-2628, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Optimization method of MRI scan parameters of a double inversion recovery sequence using a T1 map and a developed analysis algorithm

BACKGROUND

Optimizing scan parameters for double inversion recovery (DIR) sequences remains difficult.

OBJECTIVE

To evaluate a new method for optimizing DIR sequence scan parameters using T1 mapping and a newly developed analysis algorithm.

METHODS

Twelve healthy volunteers underwent T1 mapping and DIR magnetic resonance imaging. The following steps were used for image optimization including: 1) measurement of gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) T1 values to create a T1 map; 2) calculation of optimized scan parameters by using a developed analysis algorithm; 3) performance assessment of DIR magnetic resonance imaging by using the calculated optimized imaging parameters. Additionally, we used scan parameters from previous studies to obtain DIR images in order to evaluate our new method. The contrast between GM and suppressed tissues was compared between these images and those obtained using the optimized parameters.

RESULTS

Using our optimization method, WM and CSF regions were suppressed uniformly for all scan conditions. The contrast was significantly higher in images obtained using this optimization method compared to those obtained using previously published parameters (p < 0.01).

CONCLUSIONS

It is possible to obtain superior DIR images by using an optimization method that involves T1 mapping and a newly developed analysis algorithm.

Double Inversion Recovery Magnetic Resonance Imaging in Identifying Focal Cortical Dysplasia

BACKGROUND

Focal cortical dysplasia is commonly recognized in pediatric epilepsy surgery. Despite characteristic radiographic features, focal cortical dysplasia can be subtle on magnetic resonance imaging. Double inversion recovery acquisition suppresses the white matter signal, which may enhance visualization of abnormal features at the gray-white matter interface. We assessed the ability of double inversion recovery to distinguish focal cortical dysplasia from periventricular nodular heterotopia and normal brain.

METHODS

Patients with focal cortical dysplasia were identified from our patient database, as was a control group comprising patients with periventricular nodular heterotopia and healthy persons. A senior neuroradiologist reviewed all clinical images and classified them as patients with focal cortical dysplasia (n = 16) or control subjects (periventricular nodular heterotopia, n = 13; normal, n = 20). Four neuroradiologists reviewed the de-identified and randomized double inversion recovery and magnetization prepared rapid acquired gradient echoes (MPRAGE) sequences for each person and scored them as normal, focal cortical dysplasia, or periventricular nodular heterotopia.

RESULTS

Among individual reviewers, double inversion recovery showed sensitivity from 50% to 88% and specificity from 67% to 91% in detecting focal cortical dysplasia. The sensitivity was notably higher in reviewers with more clinical experience with the technique. Consensus agreement among the three most experienced reviewers gave a sensitivity of 88% (95% confidence interval [CI], 72% to 97%) and specificity of 88% (95% CI, 62% to 98%) for double inversion recovery and sensitivity of 44% (95% CI, 20% to 70%) and specificity of 100% (95% CI, 89% to 100%) for MPRAGE.

CONCLUSIONS

Double inversion recovery is sensitive for detection of focal cortical dysplasia with experienced users, particularly when there is consensus agreement. The use of two clinically available magnetic resonance imaging acquisitions-double inversion recovery and another sequence with high specificity such as MPRAGE-would be complementary in the evaluation of lesional epilepsy.

3T Double Inversion Recovery Magnetic Resonance Imaging: diagnostic advantages in the evaluation of cortical development anomalies

PURPOSE

The aim of this work was to investigate the diagnostic value of the DIR sequence at 3T MR imaging operating in the evaluation of cortical development anomalies.

METHODS

We studied 40 patients, with a previous diagnosis of cortical dysplasia, by FLAIR-3D, DIR, FSE T2 and MPR-GE T1 sequences at 3T MRI. Two independent observers evaluated, for each sequence and lesion, some semiological aspects (cortical thickness, cortical signal intensity, white-gray matter blurring, subcortical white matter intensity). We made also a quantitative evaluation of the cortical signal intensity in lesion site, drawing a ROI on each MRI sequences and comparing them to the correspondent normal contralateral cortical area.

RESULTS

We identified 44 cortical development anomalies. Qualitative analyses showed a high level of agreement between the observers concerning DIR potentialities in detecting and characterizing the cortical development disorders. Particularly DIR sequence was able to demonstrate the blurring and the subcortical white matter anomalies. The quantitative analyses didn't show a significant difference between DIR and traditional sequences in the evaluation of the cortical signal intensity.

CONCLUSION

3T MRI-DIR sequence is a useful and better suitable sequence compared to the traditional sequences in the characterization of some semiological aspects of the cortical development disorders, particularly blurring and subcortical white matter hyperintensity.

Human health risks due to heavy metals through consumption of wild mushrooms from Macheke forest, Rail Block forest and Muganyi communal lands in Zimbabwe

The levels and sources of toxic heavy metals in Amanita loosii (AL) and Cantharellus floridulus (CF) mushrooms and their substrates were studied in some parts of Zimbabwe, Rail Block forest (mining town), Macheke forest (commercial farming), and Muganyi communal lands. The mushrooms and their associated soils were acid digested prior to Al, Pb, and Zn determination by inductively coupled plasma optical emission spectroscopy. The transfer factors, mushrooms-soil metal correlation coefficients, daily intake rates, weekly intake rates, and target hazard quotients were calculated for each metal. The concentration of Zn, Al and Pb in mushrooms ranged from 1.045 ± 0.028 to 7.568 ± 0.322, 0.025 ± 0.001 to 0.654 ± 0.005, and a maximum of 5.78 ± 0.31 mg/kg, respectively, in all the three sampling areas. The mean heavy metal concentrations among the three sampling areas decreased as follows: Rail Block forest (mining town) > Macheke forest (commercial farming) > Muganyi communal lands for the concentrations in both mushrooms and total concentration in their substrates. C. floridulus accumulated higher concentrations of Al, Zn, and Pb than A. loosii at each site under study. Zn in both AL and CF (Muganyi communal lands) and Pb in AL (Rail Block forest) were absorbed only from the soils, while other sources of contamination were involved elsewhere. The consumption of 300 g of fresh A. loosii and C. floridulus per day by children less than 16 kg harvested from Rail Block forest would cause health problems, while mushrooms from Macheke Forest and Muganyi communal lands were found to be safe for human consumption. Due to non-biodegradability and bioaccumulation abilities of heavy metals, people are discouraged to consume A. loosii and C. floridulus from Rail Block forest for they have significant levels of heavy metals compared to those from Macheke forest and Muganyi communal lands.

Biologically recycled continental iron is a major component in banded iron formations

Banded iron formations (BIFs) record a time of extensive Fe deposition in the Precambrian oceans, but the sources and pathways for metals in BIFs remain controversial. Here, we present Fe- and Nd-isotope data that indicate two sources of Fe for the large BIF units deposited 2.5 billion y ago. High-εNd and -δ(56)Fe signatures in some BIF samples record a hydrothermal component, but correlated decreases in εNd- and δ(56)Fe values reflect contributions from a continental component. The continental Fe source is best explained by Fe mobilization on the continental margin by microbial dissimilatory iron reduction (DIR) and confirms for the first time, to our knowledge, a microbially driven Fe shuttle for the largest BIFs on Earth. Detailed sampling at various scales shows that the proportions of hydrothermal and continental Fe sources were invariant over periods of 10(0)-10(3) y, indicating that there was no seasonal control, although Fe sources varied on longer timescales of 10(5)-10(6) y, suggesting a control by marine basin circulation. These results show that Fe sources and pathways for BIFs reflect the interplay between abiologic (hydrothermal) and biologic processes, where the latter reflects DIR that operated on a basin-wide scale in the Archean.

Estimation of the total rectal dose of radical external beam and intracavitary radiotherapy for uterine cervical cancer using the deformable image registration method

We adapted the deformable image registration (DIR) technique to accurately calculate the cumulative intracavitary brachytherapy (ICBT) and external beam radiotherapy (EBRT) rectal dose for treating uterine cervical cancer. A total of 14 patients with primary cervical cancer radically treated with ICRT and EBRT were analysed using the Velocity AI(TM) software. Computed tomography (CT) images were registered, and EBRT and ICBT dose distributions were determined. Cumulative D2cm (3), D1cm (3) and D0.1cm (3) were calculated by simple addition of fractional values or by DIR. The accuracy of DIR was evaluated by means of a virtual phantom mimicking the rectum. The dice similarity coefficient (DSC) was calculated to evaluate rectal contour concordance between CT images before and after DIR. Virtual phantom analysis revealed that the average difference between the DIR-based phantom Dmean and the simple phantom Dmean was 1.9 ± 2.5 Gy (EQD2), and the DIR method included an uncertainty of ∼8.0%. The mean DSC between reference CT and CT was significantly improved after DIR (EBRT: 0.43 vs 0.85, P < 0.005; ICBT: 0.60 vs 0.87, P < 0.005). The average simple rectal D2cm (3), D1cm (3) and D0.1cm (3) values were 77.6, 81.6 and 91.1 Gy (EQD2), respectively; the DIR-based values were 76.2, 79.5 and 87.6 Gy, respectively. The simple addition values were overestimated, on average, by 3.1, 3.7 and 5.5 Gy, respectively, relative to the DIR-based values. In conclusion, the difference between the simple rectal dose-volume histogram (DVH) parameter addition and DIR-based cumulative rectal doses increased with decreasing DVH parameters.

On voxel-by-voxel accumulated dose for prostate radiation therapy using deformable image registration

Since delivered dose is rarely the same with planned, we calculated the delivered total dose to ten prostate radiotherapy patients treated with rectal balloons using deformable dose accumulation (DDA) and compared it with the planned dose. The patients were treated with TomoTherapy using two rectal balloon designs: five patients had the Radiadyne balloon (balloon A), and five patients had the EZ-EM balloon (balloon B). Prostate and rectal wall contours were outlined on each pre-treatment MVCT for all patients. Delivered fractional doses were calculated using the MVCT taken immediately prior to delivery. Dose grids were accumulated to the last MVCT using DDA tools in Pinnacle3 TM (v9.100, Philips Radiation Oncology Systems, Fitchburg, USA). Delivered total doses were compared with planned doses using prostate and rectal wall DVHs. The rectal NTCP was calculated based on total delivered and planned doses for all patients using the Lyman model. For 8/10 patients, the rectal wall NTCP calculated using the delivered total dose was less than planned, with seven patients showing a decrease of more than 5% in NTCP. For 2/10 patients studied, the rectal wall NTCP calculated using total delivered dose was 2% higher than planned. This study indicates that for patients receiving hypofractionated radiotherapy for prostate cancer with a rectal balloon, total delivered doses to prostate is similar with planned while delivered dose to rectal walls may be significantly different from planned doses. 8/10 patients show significant correlation between rectal balloon anterior-posterior positions and some VD values.

Depression-like behaviors in mice subjected to co-treatment of high-fat diet and corticosterone are ameliorated by AICAR and exercise

Major depressive disorder (MDD) and type II diabetes mellitus (T2DM) are highly co-morbid, and there may be a bi-directional connection between the two. Herein, we have described a mouse model of a depression-like and insulin-resistant (DIR) state induced by the co-treatment of high-fat diet (HFD) and corticosterone (CORT). 5-Aminoimidazole-4-carboxamide-1-β-d- ribofuranoside (AICAR), a pharmacological activator of AMP-activated protein kinase (AMPK), was originally used to improve insulin resistance (IR). Interestingly, our results show a clear potential for AICAR as a putative antidepressant with a chronic action on the DIR mice. In contrast to the traditional antidepressants, AICAR as a promising antidepressant avoids reducing insulin actions of skeletal muscle in the context of long-term HFD. Exercise also produced antidepressant effects. Our data suggest that the effects of AICAR and exercise on DIR may further increase our understanding on the link between depression and diabetes.

Is 3D MPRAGE better than the combination DIR/PSIR for cortical lesion detection at 3T MRI?

BACKGROUND AND OBJECTIVES

Based on the application of newer magnetic resonance imaging (MRI) acquisition sequences, the detection of cortical lesions (CL) in multiple sclerosis (MS) has significantly improved. Double inversion recovery (DIR) at 3T has increased the detection sensitivity and classification specificity when combined with phase sensitive inversion recovery (PSIR). Previous findings with 3D magnetization prepared rapid acquisition with gradient echo (MPRAGE) sequences, showed improved classification specificity of purely intracortical (IC) and mixed (MX) lesions, compared to the classification based on DIR/PSIR. Direct comparison between the detection of CL by 3D MPRAGE and by DIR/PSIR at 3T has not been evaluated.

METHODS

Eleven subjects were imaged on a 3T magnet. DIR/PSIR and 3D MPRAGE images were reviewed independently. Each image set was reviewed twice; only lesions detected on both sessions were scored. Review time per scan was ~5min for DIR/PSIR and ~15min for 3D MPRAGE.

RESULTS

We identified 141 CL (62 IC+79 MX) based on DIR/PSIR images vs. 93 (38 IC+55 MX) based on MPRAGE from all eleven patients. MPRAGE under-detected the number of CL in seven cases and over-detected the number of CL in three, only one case had the same number of CL on both sets of images.

CONCLUSIONS

Combination DIR/PSIR at 3T is superior to 3D MPRAGE for detection of cortical gray matter lesions in MS. The contrast-to-noise ratio of CL appears to be inferior on the MPRAGE images relative to DIR/PSIR.

Neurodegeneration and inflammation in hippocampus in experimental autoimmune encephalomyelitis induced in rats by one--time administration of encephalitogenic T cells

Cognitive dysfunction is relatively frequent in multiple sclerosis (MS) and it happens from the early stages of the disease. There is increasing evidence that the grey matter may be involved in autoimmune inflammation during relapses of MS. The purpose of this study was to evaluate if a single transfer of encephalitogenic T cells, mimicking a relapse of MS, may cause hippocampal damage and memory disturbances in rats. Lewis rats were injected with anti-MBP CD4+ T cells, that induced one-phase autoimmune encephalomyelitis (EAE) with full recovery from motor impairments at 10-15 days. The spatial learning and memory were tested by the Morris water maze test in control and EAE animals, 30 and 90 days post-induction (dpi). The neural injury and inflammation was investigated in the hippocampus by immunohistochemistry and quantitative analyses. There was a marked decrease in the number of CA1 and CA4 pyramidal neurons 5 dpi. The loss of neurons then aggravated till the 90 dpi. An increase in microglial and astroglial activation and in pro-inflammatory cytokines mRNA expression in the hippocampus, were present 30 and 90 dpi. Nerve growth factor and brain-derived neurotrophic factor mRNA levels were also significantly elevated. The water maze test, however, did not reveal memory deficits. The present data indicate that a single transfer of autoimmune T cells results in preserved inflammation and probable on-going neuronal injury in the hippocampus, long after recovery from motor disturbances. These findings suggest that any relapse of the MS may start the neurodegenerative process in the hippocampus, which is not necessarily connected with memory deficits.

The plasma membrane proteome of maize roots grown under low and high iron conditions

Iron (Fe) homeostasis is essential for life and has been intensively investigated for dicots, while our knowledge for species in the Poaceae is fragmentary. This study presents the first proteome analysis (LC-MS/MS) of plasma membranes isolated from roots of 18-day old maize (Zea mays L.). Plants were grown under low and high Fe conditions in hydroponic culture. In total, 227 proteins were identified in control plants, whereas 204 proteins were identified in Fe deficient plants and 251 proteins in plants grown under high Fe conditions. Proteins were sorted by functional classes, and most of the identified proteins were classified as signaling proteins. A significant number of PM-bound redox proteins could be identified including quinone reductases, heme and copper-containing proteins. Most of these components were constitutive, and others could hint at an involvement of redox signaling and redox homeostasis by change in abundance. Energy metabolism and translation seem to be crucial in Fe homeostasis. The response to Fe deficiency includes proteins involved in development, whereas membrane remodeling and assembly and/or repair of Fe-S clusters is discussed for Fe toxicity. The general stress response appears to involve proteins related to oxidative stress, growth regulation, an increased rigidity and synthesis of cell walls and adaption of nutrient uptake and/or translocation. This article is part of a Special Issue entitled: Plant Proteomics in Europe.