Mm For S1 Research Articles

Assessment of sacral osseous fixation pathways for same-level dual transiliac-transsacral screw insertion.

The purpose of this study is to (1) describe a pre-operative planning technique using non-reformatted CT images for insertion of multiple transiliac-transsacral (TI-TS) screws at a single sacral level, (2) define the parameters of a sacral osseous fixation pathway (OFP) that will allow for insertion of two TI-TS screws at a single level, and (3) identify the incidence of sacral OFPs large enough for dual-screw insertion in a representative patient population. Retrospective review at a level-1 academic trauma center of a cohort of patients with unstable pelvic injuries treated with two TI-TS screws in the same sacral OFP, and a control cohort of patients without pelvic injuries who had CT scans for other reasons. Thirty-nine patients had two TI-TS screws at S1. Eleven patients, all with dysmorphic osteology, had two TI-TS screws at S2. The average pathway size in the sagittal plane at the level the screws were placed was 17.2mm in S1 vs 14.4mm in S2 (p = 0.02). Twenty-one patients (42%) had screws that were intraosseous and 29 (58%) had part of a screw that was juxtaforaminal. No screws were extraosseous. The average OFP size of intraosseous screws was 18.1mm vs. 15.5mm for juxtaforaminal screws (p = 0.02). Fourteen millimeters was used as a guide for the lower limit of the OFP for safe dual-screw fixation. Overall, 30% of S1 or S2 pathways were ≥ 14mm in the control group, with 58% of control patients having at least one of the S1 or S2 pathways ≥ 14mm. OFPs ≥ 7.5mm in the axial plane and 14mm in the sagittal plane on non-reformatted CT images are large enough for dual-screw fixation at a single sacral level. Overall, 30% of S1 and S2 pathways were ≥ 14mm and 58% of control patients had an available OFP in at least one sacral level.

Investigating the Accuracies in Short-Term Weather Forecasts and Its Impact on Irrigation Practices

The effectiveness of irrigation schedules and crop growth models is largely dependent on the accuracies associated with the most uncertain input parameter, viz. weather forecasts. This research is focused on quantifying the inaccuracies associated with the India Meteorological Department (IMD) issuing short-term weather forecasts (with 1–5 days lead time), and their propagation into irrigation models, with an objective to select the optimal parameters for use with simulation. While precipitation (P) forecasts were directly used, remaining meteorological forecasts were converted to reference evapotranspiration (ET0) forecasts. The effectiveness of the ‘P’ and ‘ET0’ forecasts was found to be low at all lead times. We applied two popular bias correction methods: linear scaling (LS) and empirical quantile mapping (EQM), and observed a marginal improvement in forecast skill. Bias-corrected, forecast-driven irrigation scenarios, along with conventional irrigation (that ignores weather forecast), and a hypothetical perfect 5-day forecast-based irrigation (as reference) system were tested on a water-intensive paddy crop for two growing seasons (S1: monsoon and S2: winter). Conventional irrigation resulted in the highest use of irrigation water (820 mm in S1, 880 mm in S2) and percolation loss (1,140 mm in S1, 680 mm in S2), while achieving a low relative yield (0.88 in S1, 0.87 in S2). LS-corrected forecasts outperformed other scenarios with 20.24%±4.21% and 1.25%±1.51% savings in irrigation costs for S1 and S2, respectively. While IMD forecasts greatly improved irrigation schedules in the monsoon season, their usage for winter crops was found to be trivial. Our findings conclude that LS-corrected IMD forecasts were moderately reliable over multiple lead times and can serve as a valuable addition to irrigation scheduling, provided the contribution of ‘P’ to the total water balance is significant.

Estimation, modeling, and prediction of land subsidence using Sentinel-1 time series in Tehran-Shahriar plain: A machine learning-based investigation

Land subsidence (LS) is a major geologic hazard threatening most areas in Iran due to excessive groundwater extractions. The main objective of this study was to estimate LS applying PS-InSAR technique and then model and predict it through machine learning methods. Sentinel-1 time series images were used to retrieve LS from 2014 to 2019. Random forest regression (RFR) and artificial neural networks (ANN) were implemented to model LS of 2014–2017 using some conditioning factors including groundwater level decline, aquifer media, precipitation rate, slope, landuse type, depth to water table, distance from exploiting wells, distance from rivers and distance from faults as independent variables. The best calibrated method was used to predict LS over 2018–2019. In addition, all k-combinations (k=1: n, n is the number of factors) of conditioning factors were evaluated to identify the best combination resulting in the best output. The procedure was examined in the Southwest of Tehran and Shahriar plain, Iran. The maximum cumulative displacement values were 561.78 and 638.5 mm for Tehran and Shahriar, respectively. The accuracy assessment showed the RMSE value of 9.97 mm for LS retrieval. The experimental results of LS modeling indicated that RFR outperformed ANN, representing more robust and reliable results with the RMSE value of 1.35 mm for the both study areas. The investigation of the possible factor combinations showed that using the 4-factor combination consisting of precipitation, ground water table change and depth to water table along with distance from faults for S1 and the thickness of fine-grained soil layers (clay and silt) for S2 have presented promising results in modeling and predicting LS. Using all the conditioning factors, LS was predicted with RMSE value of 2.53 mm and 2.09 mm for S1 and S2, respectively. Using the 4-factor combination, however, the prediction RMSE increased by 0.13 mm and 0.04 mm for S1 and S2, respectively. This 5-percent difference can be ignored against decreasing the total cost of applying all factors. This study demonstrates the usability of processing Sentinel-1 data for LS retrieval and applying RFR for LS prediction.

Comparison of Whole Heart Computed Tomography Scanners for Image Quality Lower Radiation Dosing in Coronary Computed Tomography Angiography: The CONVERGE Registry

Novel technology in coronary computed tomographic angiography allows assessment of coronary artery disease with high image quality (IQ). There are currently two wide detector "whole heart" coverage scanners available, which avoid misregistration artifacts. However, there are no data directly comparing IQ between the two scanners. The aim of the current study is to investigate if IQ is different between the most scanners of GE and Toshiba broad detector scanners. Prospective, observational, multicenter international cohort study comparing 236 consecutive patients who underwent coronary computed tomographic angiography using whole-heart scanners; 126 patients on scanner S1 ( Aquilion ONE Vision, Toshiba), and 110 patients on scanner S2 (Revolution CT, GE Healthcare). Hounsfield units were measured using regions of interest in the descending aorta at 6 points (cranial slice, level of the visualized first, second, third, and fourth spines, and the caudal slice). We also compared the coverage length (z-axis) of the full width field of view between a single rotation of the two scanners. Evaluating mean CT attenuation values Hounsfield units through the scan range, are progressively reduced across the descending aorta in the S1 group, resulting in the larger difference of contrast brightness between the cranial and caudal slices compared to the S2 group (absolute difference: S2 13.0 ± 4.4 vs S1 141.9 ± 16.4, p < 0.0001; Percent difference: 19.3 ± 2.1 vs -3.4 ± 1.2, <0.0001). The standard deviation (SD) is similar at the cranial slice between the two scanners, however, the S1 group demonstrated higher SD-differential from cranial to caudal than S2 group. Median radiation exposure was significantly lower for the S2 scanner 1.50 ± 0.75 mSv vs the S1 system 1.9 mSv (IQR 1.7-2.7 mSv) (p = 0.01). Z-axis coverage was larger for the S2 scanner 152.5 mm (244 slices × 0.625 mm/slice) than 133 mm for S1 (266 slices × 0.5 mm/slice). Although both "volume" scanners cover the whole heart z-axis with one beat, scans using the S1 scanner have a larger variability in attenuation values throughout the scan range, resulting in 20% increase in nonuniformity from cranial to caudal slice. Additionally, SD variation across the field of view, a metric of noise, is larger when using the S1 scanner vs the S2 scanner. These results indicate that the GE Revolution CT has more uniform contrast enhancement and more coverage, lower radiation and lower image noise compared to the Toshiba Aquilion ONE Vision system.

Effects of irrigation uniformity on yield response and production economics of maize in a semiarid zone

Optimized irrigation scheduling to better match applied water to crop requirements can reduce the consumptive use of water and energy, improve water use efficiency, and increase gross profit margin. However, the distribution uniformity of applied irrigation can modify the way reduced water applications influence field-averaged performance, especially for crops sensitive to water stress as maize, in which the most sensitive stages are those related with reproduction and grain formation. We evaluated the effect of irrigation uniformity on the yield and profitability of maize (Zea Mays L.) in Albacete, Spain in two adjacent sectors equipped with a solid set sprinkler irrigation system of a field managed according to FAO-56 methodology throughout the growing season to maximize grain yield without water stress (Sector S1) or irrigation scheduling determined by an experienced producer (Sector S2). Irrigation uniformity was evaluated using catch cans in both fields and grain yield was harvested within zones exhibiting 75% (Z1), 100% (Z2), and 125% (Z3) of area-averaged volume applications throughout the year. The average coefficient of uniformity (CU) in both sectors (S1 and S2) was 83.5%, and the net amount of applied irrigation water totaled 709 mm in S1 and 832 mm in S2. Average grain yield in sector S2 approached the maximum expected yield of 18.4 Mg ha−1 and exhibited no significant differences in yield among zones. In contrast, sector S1 exhibited significant yield differences (p < 0.05) among zones with a measured yield in Z3 of 18.5 Mg ha−1 and a yield reduction of 1.6 Mg ha−1 and 4.0 Mg ha−1 in Z2 and Z1, respectively. Consequently, the area-averaged yield in S1 was 8% less than in S2. This last treatment was positively influenced by a higher amount of irrigation water supplied to the crop (17%), which decreased the effect of low CU (83.5%). The grain yields simulated by MOPECO for each monitoring zone within the sectors exhibited similar magnitude and trends. Because of these yield differences and the relatively low cost of irrigation water, area averaged gross margin in S1 was 18% less compared with S2. Simulations with MOPECO over a range of CU’s demonstrated that improved irrigation uniformity increased area-averaged yields and gross margin when following S1 instead of S2 strategy. The main innovations of this work were to quantify the effect of irrigation uniformity on the gross margin of a maize crop, and to highlight that in arid and semiarid areas with water scarce conditions, it is a better strategy to improve the irrigation uniformity than supply a higher amount of irrigation water to mask the lack of uniformity.

Selecting caudal fusion levels: 2year functional and stiffness outcomes with matched pairs analysis in multilevel fusion to L5 versus S1.

Controversy persists as to whether to end multilevel thoracolumbar fusions caudally at L5 or S1. Some argue that stopping at L5 may preserve greater function, but there are few data comparing functional limitations due to lumbar stiffness in patients with fusion to L5 versus S1. The aim of this study was to evaluate whether patients undergoing multilevel thoracolumbar fusions with an L5 caudal endpoint have a better lumbosacral function than patients with an S1 caudal endpoint. Patients undergoing successful thoracolumbar fusion of 5 or more levels to L5 or S1, with solid fusion at 2year follow-up, were examined from a single European center in addition to a multi-center North American database of 237 patients. In total, 40 patients with a distal stopping point of L5 were matched with a subset of 40 patients with a distal endpoint of S1±pelvic fixation. The L5 and S1 groups were matched for the final Oswestry Disability Index (ODI), Sagittal Vertical Axis (SVA C7-S1), number of fusion levels, and age. Impacts of lumbar stiffness on function as measured by the Lumbar Stiffness Disability Index (LSDI) were compared using the conditional logistic regression. After matching, there was no significant difference between the S1 and L5 groups for the final ODI (29.22±21.6 for S1 versus 29.21±21.7 for L5; p=0.98), SVA (29.5±40.3mm for S1 versus 33.7±37.1mm for L5; p=0.97), mean age (61.6±11.0years for S1 versus 58.3±12.6years for L5; p=0.23), and number of fusion levels (9.7±3.3 levels for S1 versus 9.0±3 levels for L5; p=0.34). The final 2-year postoperative LSDI scores were not significantly different between the S1 group (28.08±21.47) and L5 group(29.21±21.66) (hazard ratio 0.99, 95% CI 0.97-1.03, p=0.81). The analysis of patients with multilevel thoracolumbar fusions demonstrated that after minimum 2year follow-up, self-reported functional impacts of lumbar stiffness were not significantly different between the patients with distal endpoints of L5 versus S1. The choice of distal fusion level of L5 does not appear to retain sufficient spinal flexibility to substantially affect postoperative function. Level III.

Continuous 24-Hour Monitoring of Intraocular Pressure Patterns With a Contact Lens Sensor

OBJECTIVE To examine the safety, tolerability, and reproducibility of intraocular pressure (IOP) patterns during repeated continuous 24-hour IOP monitoring with a contact lens sensor. METHODS Forty patients suspected of having glaucoma (n=21) or with established glaucoma (n=19) were studied. Patients participated in two 24-hour IOP monitoring sessions (S1 and S2) at a 1-week interval (SENSIMED Triggerfish CLS; Sensimed AG). Patients pursued daily activities, and sleep behavior was not controlled. Incidence of adverse events and tolerability (visual analog scale score) were assessed. Reproducibility of signal patterns was assessed using Pearson correlations. RESULTS The mean (SD) age of the patients was 55.5(15.7) years, and 60% were male. Main adverse events were blurred vision (82%), conjunctival hyperemia (80%), and superficial punctate keratitis (15%). The mean (SD) visual analog scale score was 27.2(18.5) mm in S1 and 23.8(18.7) mm in S2 (P=.22). Overall correlation between the 2 sessions was 0.59 (0.51 for no glaucoma medication and 0.63 for glaucoma medication) (P=.12). Mean (SD) positive linear slopes of the sensor signal from wake to 2 hours into sleep were detected in both sessions for the no glaucoma medication group (S1: 0.40[0.34], P&lt;.001; S2: 0.33[0.30], P&lt;.01) but not for the glaucoma medication group (S1: 0.24[0.60], P=.06; S2: 0.40[0.40], P&lt;.001). CONCLUSIONS Repeated use of the contact lens sensor demonstrated good safety and tolerability. The recorded IOP patterns showed fair to good reproducibility, suggesting that data from continuous 24-hour IOP monitoring may be useful in the management of patients with glaucoma. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01319617.

Error in PubMed in: Global Burden of Visual Impairment and Blindness

To examine the safety, tolerability, and reproducibility of intraocular pressure (IOP) patterns during repeated continuous 24-hour IOP monitoring with a contact lens sensor. Forty patients suspected of having glaucoma(n=21) or with established glaucoma (n=19) were studied.Patients participated in two 24-hour IOP monitoring sessions (S1 and S2) at a 1-week interval (SENSIMED Triggerfish CLS; Sensimed AG). Patients pursued daily activities,and sleep behavior was not controlled. Incidence of adverse events and tolerability (visual analog scale score)were assessed. Reproducibility of signal patterns was assessed using Pearson correlations. The mean (SD) age of the patients was 55.5(15.7) years, and 60% were male. Main adverse events were blurred vision (82%), conjunctival hyperemia (80%),and superficial punctate keratitis (15%). The mean (SD)visual analog scale score was 27.2(18.5) mm in S1 and 23.8(18.7) mm in S2 (P=.22). Overall correlation between the 2 sessions was 0.59 (0.51 for no glaucoma medication and 0.63 for glaucoma medication) (P=.12). Mean(SD) positive linear slopes of the sensor signal from wake to 2 hours into sleep were detected in both sessions for the no glaucoma medication group (S1: 0.40 [0.34],P.001; S2: 0.33[0.30], P.01) but not for the glaucoma medication group (S1: 0.24 [0.60], P=.06; S2:0.40[0.40], P.001). Repeated use of the contact lens sensor demonstrated good safety and tolerability. The recorded IOP patterns showed fair to good reproducibility,suggesting that data from continuous 24-hour IOP monitoring may be useful in the management of patients with glaucoma. clinicaltrials.gov Identifier: NCT01319617

Lumbosacral intrathecal nerve roots: an anatomical study

The lumbosacral intrathecal anatomy is complex because of the density of nerve roots in the cauda equina. Space-occupying lesions, including disc herniation, trauma and tumor, within the spinal canal may compromise the nerve roots, causing severe clinical syndromes. The goal of this study is to provide spinal surgeons with a detailed anatomical description of the intrathecal nerve roots and to emphasize their clinical importance. Ten formalin-fixed male cadavers were studied. They were dissected with the aid of a surgical microscope, and measurements were performed. The number of dorsal and ventral roots ranged from one to three. The average diameter of roots increased from L1 to S1 (0.80 mm for L1 and 4.16 for S1), respectively. Then their diameter decreased from S1 to S5 (4.16 mm for S1, 0.46 mm for S5). The largest diameter was found at S1 and the smallest at S5. The average number of rootlets per nerve root increased from L1 to S1, then decreased (3.25 for L1, 12.6 for S1, and 1.2 for S5), respectively. The greatest rootlet number was seen at S1, and the fewest were observed at S5. The average diameter of the lateral recess gradually decreased from L1 to L4 (9.1 mm for L1; 5.96 mm for L4) and then increased at L5 level (6.06 mm); however, the diameter of the nerve root increased from L1 to L5. The midpoint of distance between the superior and inferior edge of the intradural exit nerve root was 3.47 mm below the inferior edge of the superior articular process at the L1 level, while the origin of the L5 exit root was 5.75 mm above the inferior edge. The root origin gradually ascended from L1 to L5. The findings of this study may be valuable for understanding lesions compressing intradural nerve roots and may be useful for intradural spinal procedures.

Location of the sacral pedicle, foramina, and ala on the lateral aspect of the sacrum: a radiographic study.

Twenty-one adult dry-bone sacral specimens were used to quantitatively determine the location of the sacral pedicle, foramina, and ala on the lateral radiographic view of the sacrum. The anterior and posterior sacral foramina from S1 to S3, the midlines of the anterior sacrum and cephalad border of the S1 vertebral body, and the lateral limit of the lateral sacral mass were outlined with wires. A lateral radiograph was taken, and measurements were made directly from the radiograph. The average sacral pedicle height for both male and female specimens was approximately 20 mm for S1, 12 mm for S2, and 7 mm for S3. The sacral foramina height averaged approximately 13 mm for S1 and S2, and 10 mm for S3. The average ala and S1 body-ala angles were 88 degrees and 35 degrees. The distance from the ala tip to the anterior aspect of the sacrum averaged 12 mm, and the average anterior height of the S1 vertebral body above the ala was 11 mm. These measurements, in conjunction with inlet and outlet radiographs, may aid in the recognition of the vital structures of the sacrum on the lateral radiographic view and enhance the safety of dorsal sacral screw placement.

The location of the intervertebral lumbar disc on the posterior aspect of the spine

Epidural fibrosis or scar formation is considered one cause of failed lumbar discectomy. Avoidance of unnecessary bony resection of the lamina may prevent or decrease postoperative scar formation. The knowledge of the precise location of the projection of the lumbar disc may also facilitate surgery and decrease patient morbidity. No studies exist regarding the projection of the lumbar disc on the posterior aspect of the lumbar spine. Thirty-six whole lumbar spine specimens from L1 to L5 (180 lumbar vertebrae) and sacra were used for this study. Anatomic evaluation included the distance between the superior border of the vertebral body (inferior border of the intervertebral disc) and the superiormost margin of the lumbar lamina, and the distance between the inferior border of the vertebral body (superior border of the intervertebral disc) and the inferiormost margin of the lumbar lamina. The width of the interlaminar space was also measured. The data showed that the level of the superior margin of the lamina was consistently inferior to the superior border of the corresponding vertebral body from L1 to S1. This distance for both sexes ranged from 10 to 11 mm for L1-L5 and 14 mm for S1. The level of the inferior margin of the lamina varied from 3 mm inferior to 9 mm superior to the inferior border of the corresponding vertebral body for L1-L5. The width of the interlaminar space averaged from 16.8 mm for L1 to 31.0 mm for L5. This study suggests that the superior margin of the lamina represents a consistent, useful landmark in determining the location of the lumbar disc on the posterior aspect of the spine. The relationship between the inferior margins of the lamina and the vertebral body is not consistent.

Pedicle diameter determined by computed tomography. Its relevance to pedicle screw fixation in the lumbar spine.

Intraoperative technical complications of pedicle screw fixation include screw cutout or maldirection and pedicle fracture. The aims of this study were 1) to use computed tomography to determine the average pedicle diameter; and 2) to compare these measurements with the outer diameter measurements of commonly used pedicle screws. The pedicle diameters of L2, L3, L4, L5, and S1 were measured in 154 adult patients (81 men, 73 women) who had low-back pain. The distance across the isthmus of the pedicle was measured with the distance mode on the axial computed tomographic image in the bone window setting. The lateral computed tomographic scout view was used to select the axial section through the midportion of the pedicle. To standardize data retrieval, the lower four motion segments were denoted as L2-S1, even when there were more or fewer than five lumbar vertebrae. The pedicle diameter at each level was measured and averaged for all patients and for men and women separately. The percentage of pedicles that measured less than 7 mm was determined at each level. The average pedicle diameters were 8.13 mm for L2, 8.7 mm for L3, 10.88 mm for L4, 14.54 mm for L5, and 18.37 mm for S1. Twenty percent of the L2 pedicle diameters, 15.6% of L3, and 1.9% of L4 were less than 7 mm; none of the L5 or S1 pedicles measured less than 7 mm. The outer diameters of the most commonly used pedicle screws range from 5 mm to 7 mm. Screw pitch, tooth profile, outer diameter, and depth of penetration affect implant strength.(ABSTRACT TRUNCATED AT 250 WORDS)