Fusing landscape accuracy-dependent SRTM elevation data with NGDC and LiDAR data for the Florida coastline

Extended coverage digital elevation models (DEMs) including topographic and bathymetric area at moderate resolution are needed for regional-scale hazard modelling. Shuttle Radar Topography Mission (SRTM) provides important intermediate-scale information between coarse resolution data sets of wide area and high-resolution data sets of limited area. Although there are many anthropogenic structures that cause errors in the height of SRTM data, the measurement error is given as a single value for the entire area. The filter residuals in an adaptive multi-scale fusion algorithm were used to evaluate the landscape-dependent accuracy of SRTM elevations over the Florida coastal urban area. With accuracy and employing a stochastic framework to optimally fuse National Geophysical Data Center (NGDC) data, SRTM data and high-resolution light detection and ranging data, single seamless fused DEMs at multiple scales were derived for the coastal area and improved DEM quality at 30 m scale for coastal flood prediction was demonstrated.     

Prostaglandin (PG) E2 generation by cultured canine synovial fibroblasts exposed to microcrystals containing calcium.

Immunoreactive prostaglandin (PG) E2 was released into the ambient medium in a dose dependent fashion when either hydroxyapatite (HA) or calcium pyrophosphate dihydrate (CPPD) crystals were added to canine synovial fibroblasts in tissue culture. PGE2 release peaked 6 to 9 hours after HA or CPPD crystals were added in the presence of serum but at 24 hours if they were added in the presence of lactalbumin hydrolysate. PGE2 release correlated with crystal endocytosis estimated qualitatively by serial phase contrast microscopy and time lapse photography. As postulated previously by others for monosodium urate crystals, prostaglandin production by synovial cells may also be related to the pathogenesis of the destructive arthropathies associated with HA or CPPD crystals.     

Magnetic resonance of the hepatic veins with angular reconstruction: application in living-related liver transplantation.

BACKGROUND: Preoperative mapping of the hepatic venous system of the partial liver graft is indispensable to the success of living-related liver transplantation. We assessed the accuracy of magnetic resonance (MR) venography with angular reconstruction in depicting the tributaries of the middle hepatic vein and left hepatic vein in the donors, which was essential in graft retrieval and venoplasty. METHODS: Nineteen living-related liver transplantation donors underwent a pretransplantation survey, including sonography and MRI for hepatic venous evaluation. T1-weighted images were reconstructed manually, using the inferior vena cava as a fixed point for tilting to produce an oblique plane image where both the middle hepatic vein and left hepatic vein could be demonstrated draining into the inferior vena cava. The reconstructed images of the hepatic veins were compared with preoperative sonography, intraoperative sonography, and operative findings. RESULTS: Preoperative sonography and MR findings correlated well with the operative findings in the major hepatic veins. The MR venography of the ramification of the hepatic veins has an accuracy of 93%, the sonography, 84%. Sonography is slightly inferior in the evaluation of the hepatic vein in segment 4 and the left superior hepatic vein, with an accuracy of 73% and 67%, respectively. CONCLUSION: MR venography with angular reconstruction is accurate in depicting the complex distribution of the hepatic veins of the left liver, providing important information for decision making as to the cutting plane during graft retrieval and the method of venoplasty and anastomosis. Thus, unnecessary blood loss could be avoided and vascular complications could be prevented, as these conditions would be unacceptable for a healthy living donor. We propose that MR venography, a rapid and reliable technique, is an appropriate alternative examination or complementary modality to sonography in the pretransplantation evaluation of the living donor.     

Surgical management of blunt traumatic rupture of the descending thoracic aorta.

Acute rupture of the descending thoracic aorta following blunt trauma is a life-threatening injury that requires emergent operative intervention. From February 1989 to January 1997, 4 patients with multiple injuries including traumatic rupture in the region of the aortic isthmus were surgically treated at our institution. Diagnosis was confirmed in all patients by aortogram prior to aortic repair. One patient had preoperative paraplegia secondary to an unstable spinal fracture. All patients underwent repair under cardiopulmonary bypass (3 partial, 1 total with hypothermic arrest). The site of rupture was resected and replaced with an interposition artificial graft. There was no perioperative mortality and no additional occurrence of paraplegia. Our experience and a review of the literature indicate that for survivors of traumatic aortic rupture, excellent outcomes can be achieved only if the diagnosis is made early and the surgical treatment is prompt.     

Rebound kinetics of beta2-microglobulin after hemodialysis.

BACKGROUND: Evaluation of beta2-microglobulin (beta2m) removal during hemodialysis using predialysis and immediate postdialysis plasma concentrations is only valid in the absence of postdialysis rebound. Postdialysis rebound of beta2m has not been studied extensively, and its importance in the determination of beta2m clearance is unknown. METHODS: We evaluated the kinetics of urea and beta2m in a crossover study of 10 chronic hemodialysis patients using dialyzers with similar urea mass transfer-area coefficients containing either low-flux cellulose acetate or high-flux cellulose triacetate membranes. Kinetics were examined during and following a 210 minute treatment by measuring plasma concentrations predialysis at regular intervals during therapy and at 0, 2, 10, 20, 30, and 60 minutes postdialysis. Clearances of urea and beta2m were also determined directly from the arterial and venous concentration differences across the dialyzer at 60 minutes after starting dialysis. RESULTS: By design, urea removal was similar for both low-flux and high-flux dialyzers as assessed by the urea reduction ratio and Kt/V. Postdialysis urea rebound was similar for low- and high-flux dialyzers; the rebound in the plasma urea nitrogen concentration (expressed as a percentage of the intradialytic decrease in plasma concentration) was 9.2 +/- 1.9% (mean +/- SEM) at 30 minutes postdialysis and 13.0 +/- 1.4% at 60 minutes postdialysis for a single pool urea Kt/V of 1.16 +/- 0.05. The plasma beta2m concentration increased by 11.1 +/- 3.0% during the treatment using the low-flux dialyzer but decreased by 27.1 +/- 4.0% during the treatment using the high-flux dialyzer. When using the high-flux dialyzer, the rebound of beta2m was 44.8 +/- 21.4% at 30 minute postdialysis and 45.9 +/- 15.9% at 60 minutes postdialysis. The clearance of beta2m for the high-flux dialyzer calculated from predialysis and immediate postdialysis plasma concentrations using a single-compartment model (28.2 +/- 4.4 ml/min) was higher (P < 0.05) than that determined directly across the dialyzer (18.3 +/- 2.0 ml/min). If either the 30- or 60-minute postdialysis plasma beta2m concentration was used instead, the calculated beta2m clearance (16. 5 +/- 4.8 ml/min or 15.6 +/- 2.8 ml/min, respectively) was similar to that determined directly across the dialyzer. CONCLUSIONS: Postdialysis rebound of beta2m when using high-flux dialyzers is substantial; neglecting postdialysis rebound results in an overestimation of beta2m clearance when calculated using a single-compartment model.     

Radiation oncology and medical physicists quality assurance in British Columbia Cancer Agency Provincial Prostate Brachytherapy Program

PurposeTo describe in detail British Columbia (BC) Cancer Agency (BCCA) Provincial Prostate Brachytherapy (PB) Quality Assurance (QA) Program.Methods and MaterialsThe BCCA PB Program was established in 1997. It operates as one system, unified and supported by electronic and information systems, making it a single PB treatment provider for province of BC and Yukon. To date, >4000 patients have received PB (450 implants in 2011), making it the largest program in Canada. The Program maintains a large provincial prospective electronic database with records on all patients, including disease characteristics, risk stratification, pathology, preplan and postimplant dosimetric data, follow-up of prostate-specific antigen, and toxicity outcomes.ResultsQA was an integral part of the program since its inception. A formal QA Program was established in 2002, with key components that include: unified eligibility criteria and planning system, comprehensive database, physics and oncologist training and mentorship programs, peer review process, individual performance outcomes and feedback process, structured continuing education and routine assessment of the program's dosimetry, toxicity and prostate-specific antigen outcomes, administration and program leadership that promotes a strong culture of patient safety. The emphasis on creating a robust, broad-based network of skilled providers has been achieved by the program's requirements for training, education, and the QA process.ConclusionsThe formal QA process is considered a key factor for the success of cancer control outcomes achieved at BCCA. Although this QA model may not be wholly transferable to all PB programs, some of its key components may be applicable to other programs to ensure quality in PB and patient safety.     

Imaging findings in hippocampal sclerosis: correlation with pathology

We evaluated the ability of preoperative radiologic imaging to detect hippocampal sclerosis in 31 patients who underwent surgery for intractable epilepsy. Hippocampal sclerosis is commonly associated with surgically treatable temporal lobe epilepsy. It is pathologically described as neuronal cell loss with associated gliosis in the hippocampus. While previous reports have correlated imaging results with clinical or qualitative histologic findings, this study used quantitative pathologic criteria (neuronal cell density) to diagnosis hippocampal sclerosis. We focused our study on the 11 patients with cryptogenic temporal lobe epilepsy. Of these, nine had hippocampal sclerosis by pathologic criteria. MR findings included unilateral hippocampal atrophy, an increased signal in the hippocampus on long TR scans, and atrophy in the adjacent white matter and temporal lobe. Hippocampal atrophy was most frequently seen in the red nucleus plane on coronal scans, corresponding to the body of the hippocampus. We also compared hippocampal size on MR with neuronal density in surgical specimens of the 11 patients with cryptogenic temporal lobe epilepsy. A statistically significant correlation was found between MR size and neuronal density in CA3 and CA4 of the cornu ammonis and the granular cell layer of the hippocampus. Since temporal lobectomy eliminated seizures in seven of nine patients with hippocampal sclerosis, preoperative diagnosis by MR has important therapeutic consequences.     

Changes in bone mineral density in men starting androgen deprivation therapy and the protective role of vitamin D

Summary

Androgen deprivation therapy in 80 men was associated with declines in bone mineral density (BMD), which were greatest in the first year, and in the lumbar spine compared to controls. Vitamin D use was associated with improved BMD in the lumbar spine and in the first year.

Introduction

Decreased BMD is a common side effect of androgen deprivation therapy (ADT), leading to increased risk of fractures. Although loss of BMD appears to be greatest within the first year of starting ADT, there are few long-term studies of change in BMD, and risk factors for bone loss are not well-characterized.

Methods

Men aged 50+ with nonmetastatic prostate cancer starting continuous ADT were enrolled in a prospective longitudinal study. BMD was determined by dual-energy x-ray absorptiometry at baseline and yearly for 3 years. Matched controls were men with prostate cancer not receiving ADT. Multivariable regression analysis examined predictors of BMD loss.

Results

Eighty ADT users and 80 controls were enrolled (mean age 69 years); 52.5 % had osteopenia and 8.1 % had osteoporosis at baseline. After 1 year, in adjusted models, ADT was associated with significant losses in lumbar spine BMD compared to controls (?2.57 %, p?=?0.006), with a trend towards greater declines at the total hip (p?=?0.09). BMD changes in years 2 and 3 were much smaller and not statistically different from controls. Use of vitamin D but not calcium was associated with improved BMD in the lumbar spine in year 1 (+6.19 %, p?<?0.001) with smaller nonsignificant increases at other sites (+0.86 % femoral neck, +0.86 % total hip, p?>?0.10) primarily in the first year.

Conclusions

Loss of BMD associated with ADT is greatest at the lumbar spine and in the first year. Vitamin D but not calcium may be protective particularly in the first year of ADT use.     

Digital subtraction in gadolinium-enhanced MR imaging of the brain: a method to reduce contrast dosage

The aim of the study was to investigate the feasibility of using digital subtraction in contrast-enhanced MR imaging of the brain to reduce the MR contrast dosage without jeopardizing patient care. Fifty-two patients with intracranial lesions, either intra-axial or extra-axial, detected by computerized tomography were selected for contrast-enhanced MR imaging with half-dose and full-dose of gadopentetate dimeglumine. The half-dose unsubtracted, full-dose unsubtracted, and half-dose subtracted MR images were visually assessed by counting the number of enhancing brain lesions in the images and quantitatively analyzed by computing their lesion contrast-to-background ratios (CBR). The visual conspicuity of the half-dose subtracted MR images was comparable to that of the full-dose unsubtracted MR images ( p>0.05), whereas the CBR of the half-dose subtracted images was approximately two to three times higher than that of the full-dose unsubtracted images. The half-dose subtracted T1-weighted spin-echo images might be able to replace the conventional standard-dose T1-weighted spin-echo images in MR imaging of the brain.