WE-G-217BCD-07: Implementation and Evaluation of Helical On-Board CBCT and Exact Image Reconstruction

PURPOSE

Longitudinal coverage of CBCT, which is 17 cm for head scan and 15.5 cm for body scan, is not enough to cover the entire PTV for over 90% of head/neck and gastrointestinal/genitourinary/gynecologic patients if lymph nodes are involved. Helical CBCT, which was accomplished using external beam LINAC in its research mode, is one promising way to extend the CBCT longitudinal coverage. Aim of this study is to compare Katsevich's exact algorithm with traditional FDK algorithm for helical CBCT image reconstruction.

METHODS

CBCT projection raw data were acquired on a TrueBeam LINAC machine (Varian Medical Systems) in the research mode in helical trajectories that encompass a 360 degree rotation, 25 cm pitch, 100 kVp, 80 mA, and 25 ms, with a Catphan 600. Reconstruction was done with Katsevich's exact and FDK approximate algorithms. Scatter correction, beam-hardening correction, and non-uniform gantry angle correction, are performed on projection data to reduce artifacts and noise. Image qualities (CT number accuracy, uniformity, SNR) were evaluated and compared between the reconstruction algorithms.

RESULTS

Images reconstructed by Katsevich's algorithm show better qualities, compared to ones by FDK algorithm and HU numbers have higher uniformity and accuracy. The HU-density calibration curve closely conforms to the manufacturer recommended values. The level of noise computed as the standard deviation in the phantom uniform region is 28.07 for the Katsevich algorithm, compared to 44.64 for the FDK algorithm.

CONCLUSIONS

Katsevich's exact reconstruction algorithm provided better image qualities than FDK for helical CBCT scans. This result will very useful for our ongoing investigation of helical CBCT, which would lead to improvement of CBCT longitudinal coverage of PTV and would be essential for future image-guided adaptive radiation therapy applications. Varian Research Agreement with Washington University in St. Louis.

SU-F-BRCD-09: Total Variation (TV) Based Fast Convergent Iterative CBCT Reconstruction with GPU Acceleration

PURPOSE

To improve image quality and reduce imaging dose in CBCT for radiation therapy applications and to realize near real-time image reconstruction based on use of a fast convergence iterative algorithm and acceleration by multi-GPUs.

METHODS

An iterative image reconstruction that sought to minimize a weighted least squares cost function that employed total variation (TV) regularization was employed to mitigate projection data incompleteness and noise. To achieve rapid 3D image reconstruction (< 1 min), a highly optimized multiple-GPU implementation of the algorithm was developed. The convergence rate and reconstruction accuracy were evaluated using a modified 3D Shepp-Logan digital phantom and a Catphan-600 physical phantom. The reconstructed images were compared with the clinical FDK reconstruction results.

RESULTS

Digital phantom studies showed that only 15 iterations and 60 iterations are needed to achieve algorithm convergence for 360-view and 60-view cases, respectively. The RMSE was reduced to 10-4 and 10-2, respectively, by using 15 iterations for each case. Our algorithm required 5.4s to complete one iteration for the 60-view case using one Tesla C2075 GPU. The few-view study indicated that our iterative algorithm has great potential to reduce the imaging dose and preserve good image quality. For the physical Catphan studies, the images obtained from the iterative algorithm possessed better spatial resolution and higher SNRs than those obtained from by use of a clinical FDK reconstruction algorithm.

CONCLUSIONS

We have developed a fast convergence iterative algorithm for CBCT image reconstruction. The developed algorithm yielded images with better spatial resolution and higher SNR than those produced by a commercial FDK tool. In addition, from the few-view study, the iterative algorithm has shown great potential for significantly reducing imaging dose. We expect that the developed reconstruction approach will facilitate applications including IGART and patient daily CBCT-based treatment localization.

Assessment of the innate and adaptive immune system in proliferative vitreoretinopathy

PURPOSE

Proliferative vitreoretinopathy (PVR) is the leading cause of failure of surgery for rhegmatogenous retinal detachment. Although indirect evidence suggests that this disease might be autoimmune in nature, direct proof for this hypothesis is lacking. The purpose of this study was to determine in a murine model whether PVR can develop in the absence of T- or B-cell immunity.

METHODS

Four- to six-week-old Rag-1 gene knockout (KO) and congenic wild-type mice (WT) on the C57.Bl/6 background were studied. PVR was induced by intravitreal injection of 3 μl dispase at the concentration of 0.2 U/μl. PVR development was monitored by electroretinograms, the macroscopic observation of hemorrhage, cataract, retinal folds, and of an uneven iris, as well as the histological detection of epiretinal membranes on haematoxylin-eosin stained tissue. Additionally, immunofluorescence analysis was performed. These manifestations of PVR were assessed 1, 2, 4, 6, and 8 weeks after the intravitreal injection.

RESULTS

The data showed that the immune-deficient Rag-1 KO mice developed PVR with similar kinetics and severity as did the fully immune competent congenic WT mice. Carboxyfluorescein diacetate succinimidyl ester-labeled T cells that are specific for ovalbumin were detected in the inflamed vitreous and retina showing that T cells that are not specific for autoantigens present in the eye can migrate to PVR lesions. Therefore, the mere presence of T cells in PVR lesions does not imply an autoimmune pathogenesis.

CONCLUSION

This study suggests that T- and B-cell immunity is not essential for the induction of PVR.

Efficacy and safety of topical WBI-1001 in patients with mild to severe atopic dermatitis: results from a 12-week, multicentre, randomized, placebo-controlled double-blind trial

BACKGROUND

There is a need for the development of novel nonsteroidal topical drugs for the treatment of atopic dermatitis (AD).

OBJECTIVES

The primary objective was to evaluate the efficacy of WBI-1001 over 6 weeks of treatment of mild to severe AD.

METHODS

  Patients with AD affecting 3-20% of their body surface area and with an Investigator's Global Assessment (IGA) of 2-4 were randomized (1 : 1 : 1) to receive placebo, WBI-1001 0·5% or WBI-1001 1·0% in a cream formulation applied twice daily for 6 weeks. At the end of this phase, patients receiving WBI-1001 continued the same treatment for an additional 6 weeks. Patients receiving placebo entered into a 6-week double-blind phase with re-randomization (1 : 1) to WBI-1001 0·5% or 1·0% cream. The primary objective was to evaluate the efficacy of WBI-1001 over 6 weeks of treatment of mild to severe AD. The primary endpoint was the mean change from baseline in IGA at day 42 (week 6).

RESULTS

In total, 148 patients were randomized and analysed in the placebo (51), WBI-1001 0·5% (50) and WBI-1001 1·0% (47) groups. There was a decrease of 1·3 [43%; P < 0·001; 95% confidence interval (CI) -1·2 to -0·5] and 1·8 (56·3%; P < 0·001; 95% CI -1·6 to -0·9) in IGA at day 42 in the WBI-1001 0·5% and 1·0% groups, respectively, as compared with a decrease of 0·5 (14·7%) in the placebo group. Adverse drug reactions included a few cases of folliculitis and contact dermatitis.

CONCLUSIONS

WBI-1001 is an efficacious novel topical anti-inflammatory molecule for the treatment of AD.

Sulphoraphane inhibited the expressions of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 through MyD88-dependent toll-like receptor-4 pathway in cultured endothelial cells

BACKGROUND AND AIMS

Chronic inflammation plays pivotal roles in both cancer and cardiovascular diseases. A large body of evidence suggests that high intake of cruciferous vegetables is closely related with low risk of these disorders. However, the underlying mechanisms of protection are not fully understood. The aim of this study is to test the protective effects of an isothiocyanate sulphoraphane on inflammatory injury and related regulation pathways in cultured endothelial cells.

METHODS AND RESULTS

The expressions of adhesion molecules were determined by TaqMan real-time polymerase chain reaction (PCR) and Western blot analysis. Nuclear factor-kappa B (NF-кB) translocation was detected by immunofluorescent hybridisation. Other proteins were measured by Western blot analysis. The results demonstrated that sulphoraphane significantly suppresses the expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 stimulated by lipopolysaccharide (LPS) both at the transcriptional and translational levels. In addition, sulphoraphane inhibited the translocation of NF-кB into the nucleus. Sulphoraphane decreased the phosphorylation of extra-cellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), while further blockade and activation using individually specific agents confirm that p38 MAPK and JNK are mainly involved. Interestingly, sulphoraphane down-regulated Toll-like receptor (TLR)-4, a receptor of LPS located on the membrane. In addition, MyD88, an effector downstream TLR-4 signal pathway was subsequently attenuated.

CONCLUSION

Taken all together, adhesion molecules are confirmed to be the novel targets of sulphoraphane in preventing inflammatory insult to endothelial cells. Sulphoraphane suppressed TLR-4 followed by MyD88 and downstream factors such as p38 MAPK and JNK, ultimately blocking NF-кB translocation and the subsequent expression of adhesion molecules. These data suggested a novel inflammatory pathway mediated by sulphoraphane.

Assessing immunologic function through CD4 T-lymphocyte ahenosine triphosphate levels by ImmuKnow assay in Chinese patients following renal transplantation

OBJECTIVE

Balancing immunosuppression to prevent rejection while minimizing infection/drug toxicity risk is a challenge in organ transplantation. Drug monitoring alone or with functional monitoring is inadequate to measure the immune response after transplantation. The Food and Drug Administration (FDA)-approved immune monitoring assay, ImmuKnow, offers an noninvasive method to assess the immune status of transplanted patients by measuring adenosine triphosphate (ATP) released from CD4 T cells. Herein, we have evaluated ATP levels reflecting the immune responses of Chinese kidney transplant recipients as a monitoring parameter to guide treatment after transplantation.

METHODS

From October 2008 to March 2010, we recruited 259 kidney transplant patients who were divided into four groups: stable (n = 174), postoperative infection (n = 32), postoperative rejection (n = 16), and high-dose corticosteroid treatment (n = 33). The ImmuKnow assay was performed to measure CD4 T-cell ATP levels. No prisoners or organs from prisoners were used in the study.

RESULTS

Receiver operating characteristics measurements indicated an ATP predictive range of 238 to 497 ng/mL to monitor immune responses after transplantation and immunosuppressive therapy. To identify patients with infection, we used a cutoff ATP value of 238 ng/mL with 100% specificity and positive predictive value and 92.9% sensitivity. To identify patients with rejection, we used a value of 497 ng/mL with 91.5% sensitivity. Compared with the 225 to 525 ng/mL ATP levels recommended by the FDA, our target values showed similar or better diagnostic accuracy.

CONCLUSION

We provide additional data to monitor immunosupressant treatment of Chinese kidney transplant patients.

The lobular transposition flap: a useful adjunct to reconstruct helical defects

We detail our adjunct to Antia and Buch's chondrocutaneous advancement flap for helical reconstruction. It is simple, reliable and negates the need for transfer of the defect to the lobule and/or V-Y advancement of the helical crus.

Protein analysis as a measure of active biomass in activated sludge

Conventional methods to determine the biomass in activated sludge are the measurement of total suspended solids (TSS) and volatile suspended solids (VSS). Such methods do not distinguish between active biomass and inactive organic material. In this study, biomass was determined with both conventional methods and also through measuring the protein content with the modified Lowry method. In order to investigate the relationship between activity and biomass concentration in terms of TSS, VSS and protein content, some starvation experiments were conducted. It was found that the protein fraction of VSS differs under different starvation conditions. The biological activity of the activated sludge was measured as oxygen uptake rate (OUR). The strongest correlation could be measured between protein and OUR under various conditions. The results show that protein is an appropriate parameter for the measurement of the biological activity.

Using quantitative CT perfusion for evaluation of delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

DCI is a serious complication following aneurysmal SAH leading to permanent neurologic deficits, infarction, and death. Our aim was to prospectively evaluate the diagnostic accuracy of CTP and to determine a quantitative threshold for DCI in aneurysmal SAH.

MATERIALS AND METHODS

Patients with SAH were prospectively enrolled in a protocol approved by the institutional review board. CTP was performed during the typical time period for DCI, between days 6 and 8 following SAH. Quantitative CBF, CBV, and MTT values were obtained by using standard region-of-interest placement sampling of gray matter. The reference standard for DCI is controversial and consisted of clinical and imaging criteria in this study. In a subanalysis of vasospasm, DSA was used as the reference standard. ROC curves determined the diagnostic accuracy by using AUC. Optimal threshold values were calculated by using the patient population utility method.

RESULTS

Ninety-seven patients were included; 41% (40/97) had DCI. Overall diagnostic accuracy was 93% for CBF, 88% for MTT, and 72% for CBV. Optimal threshold values were 35 mL/100 g/min (90% sensitivity, 68% specificity) for CBF and 5.5 seconds (73% sensitivity, 79% specificity) for MTT. In the subanalysis (n = 57), 63% (36/57) had vasospasm. Overall diagnostic accuracy was 94% for CBF, 85% for MTT, and 72% for CBV. Optimal threshold values were 36.5 mL/100 g/min (95% sensitivity, 70% specificity) for CBF and 5.4 seconds (78% sensitivity, 70% specificity) for MTT.

CONCLUSIONS

CBF and MTT have the highest overall diagnostic accuracy. Threshold values of 35 mL/100 g/min for CBF and 5.5-second MTT are suggested for DCI on the basis of the patient population utility method. Absolute threshold values may not be generalizable due to differences in scanner equipment and postprocessing methods.

Unusual cause of acquired brain injury

A 37-year-old male was admitted with history of syncope and fall leading to right temporal bone fracture with extradural haemorrhage. He underwent craniotomy and clot evacuation. Postoperatively during inpatient rehabilitation, he was progressing well with his physical and cognitive rehabilitation, when he had resting tachycardia of between 90 and 100 per minute. Investigations to rule out cardio-pulmonary and endocrine causes of tachycardia were normal. He was further investigated for suspected postural orthostatic tachycardia syndrome (POTS). A tilt table test was done which revealed rise in baseline heart rate from 90/min to 130/min on 70 with no postural drop in blood pressure. Subsequently plasma norepinephrine level in erect posture was analysed which was 721 pg/ml. A working diagnosis of POTS was made. Initially, after an increase in water intake by 1.5-2 l/day, his baseline and postural tachycardia reverted back to 76/min. He is being followed up.

Y-chromosome haplotype distribution in Han Chinese populations and modern human origin in East Asians

We investigated the distribution of Y-chromosome haplotype using 19 Y-SNPs in Han Chinese populations from 22 provinces of China. Our data indicate distinctive patterns of Y chromosome between southern and northern Han Chinese populations. The southern populations are much more polymorphic than northern populations. The latter has only a subset of the southern haplotypes. This result confirms the genetic difference observed between southern and northern ethnic populations in East Asia. It supports the hypothesis that the first settlement of modern humans of African origin occurred in the southern part of East Asia during the last Ice Age, and a northward migration led to the peopling of northern China.

Mapping QTL for an adaptive trait: the length of caudal fin in Lates calcarifer

The caudal fin represents a fundamental design feature of fishes and plays an important role in locomotor dynamics in fishes. The shape of caudal is an important parameter in traditional systematics. However, little is known about genes involved in the development of different forms of caudal fins. This study was conducted to identify and map quantitative trait loci (QTL) affecting the length of caudal fin and the ratio between tail length and standard body length in Asian seabass (Lates calcarifer). One F1 family containing 380 offspring was generated by crossing two unrelated individuals. One hundred and seventeen microsatellites almost evenly distributed along the whole genome were genotyped. Length of caudal fin at 90 days post-hatch was measured. QTL analysis detected six significant (genome-wide significant) and two suggestive (linkage-group-wide significant) QTL on seven linkage groups. The six significant QTL explained 5.5-16.6% of the phenotypic variance, suggesting these traits were controlled by multiple genes. Comparative genomics analysis identified several potential candidate genes for the length of caudal fin. The QTL for the length of caudal fin detected for the first time in marine fish may provide a starting point for the future identification of genes involved in the development of different forms of caudal fins in fishes.