SU-E-J-187: Evaluation of the Effects of Dose on 4DCT-Calculated Lung Ventilation

PURPOSE

To investigate the effects of radiation therapy (RT) treatment dose on ventilation.

METHODS

Optical flow deformable image registration of the normal end-expiration and end-inspiration phases of 4DCT images was used to correlate the voxels between the two phases. 4DCT sets from before and after RT were used to derive ventilation for 3 SBRT lung patients. Planning dose and normalized ventilation were superimposed on the CT volume resulting in each voxel having a volume, a normalized ventilation and a dose. From these values a 3D dose-ventilation-volume surfaces was created. The surface was integrated over dose to reduce the 3D surface to a 2D histogram that is easier to interpret.

RESULTS

For lung tissue regions receiving more than 20 Gy, a decrease in ventilation was observed in the three patients. Patient A (time between scans, T=26 months) showed an increase in ventilation for regions receiving a dose smaller than 20 Gy, whereas patients B (T=3 months) and C (T=6 months) did not show any change for these regions. Mean ventilation within the 20 Gy region for patient A was 0.57 before RT and 0.51 after RT; and 0.54 before and 0.48 after RT for the 30 Gy region. Mean ventilation for the 20 Gy region for patient B was 0.49 before RT and 0.47 after RT, for the 30 Gy region mean ventilation was 0.49 Gy before and 0.45 Gy after RT. Patient C's mean ventilation for the 20 Gy region was 0.54 before RT and 0.50 after RT, for the 30 Gy region mean ventilation was 0.54 before RT and 0.49 after RT.

CONCLUSIONS

Ventilation before and after radiation therapy can be measured using 4DCT and deformable image registration techniques. In a preliminary application of this approach for three patients, changes in ventilation were observed with a weak correlation between ventilation change and dose. Partially supported by a grant from Varian Medical Systems.

Allergic airway hyperreactivity increases the risk for corneal allograft rejection

Corneal allografts transplanted into hosts with allergic conjunctivitis experience an increased incidence and swifter tempo of immune rejection compared to corneal allografts transplanted to nonallergic hosts. Previous findings suggested that increased risk for rejection was not a local effect produced by an inflamed eye, but was due to perturbation of the systemic immune responses to alloantigens on the corneal allograft. We tested the hypothesis that another allergic disease, airway hyperreactivity (AHR), would also increase the risk for corneal allograft rejection. Induction of AHR with either ovalbumin (OVA) or short ragweed (SRW) extract prior to keratoplasty resulted in a steep increase in the speed and incidence of corneal allograft rejection. Delayed-type hypersensitivity (DTH) responses to corneal alloantigens were closely associated with corneal allograft rejection. However, the deleterious effect of AHR on corneal allograft survival was not reflected in a heightened magnitude of allospecific DTH, cytotoxic T lymphocyte and lymphoproliferative responses to the alloantigens on the corneal allograft. Unlike Th2-based immediate hypersensitivity, CD8+ T-cell-based contact hypersensitivity to oxazolone did not increase the risk for corneal allograft rejection. Thus, Th2-based allergic diseases significantly reduce the immune privilege of the corneal allograft and represent important risk factors for consideration in the atopic patient.

Open source software infrastructure for computational biology and visualization

The CMISS software package is used in many biological research areas for multiscale computational biology and visualization. Some major components of this suite have recently been released under an open source license, specifically modules for field storage, 3D graphics, mathematical field operators and image processing. Interfaces are being developed to facilitate integration with other applications and the Internet.

MAST3: a novel IBD risk factor that modulates TLR4 signaling

Inflammatory bowel disease (IBD) is a chronic disorder caused by multiple factors in a genetically susceptible host. Significant advances in the study of genetic susceptibility have highlighted the importance of the innate immune system in this disease. We previously completed a genome-wide linkage study and found a significant locus (IBD6) on chromosome 19p. We were interested in identifying the causal variant in IBD6. We performed a two-stage association mapping study. In stage 1, 1530 single-nucleotide polymorphisms (SNPs) were selected from the HapMap database and genotyped in 761 patients with IBD. Among the SNPs that passed the threshold for replication, 26 were successfully genotyped in 754 additional patients (stage 2). One intronic variant, rs273506, located in the microtubule-associated serine/threonine-protein kinase gene-3 (MAST3), was found to be associated in both stages (pooled P=1.8 x 10(-4)). We identified four MAST3 coding variants, including a non-synonymous SNP rs8108738, correlated to rs273506 and associated with IBD. To test whether MAST3 was expressed in cells of interest, we performed expression assays, which showed abundant expression of MAST3 in antigen-presenting cells and in lymphocytes. The knockdown of MAST3 specifically decreased Toll-like receptor-4-dependent NF-kappaB activity. Our findings are additional proofs of the pivotal role played by modulators of NF-kappaB activity in IBD pathogenesis.

Clinical effectiveness and cost-effectiveness of different models of managing long-term oral anticoagulation therapy: a systematic review and economic modelling

OBJECTIVES

To examine the clinical effectiveness and cost-effectiveness of self-testing and self-management of oral anticoagulation treatment compared with clinic-based monitoring.

DATA SOURCES

Major electronic databases were searched up to September 2005.

REVIEW METHODS

A systematic review was undertaken of relevant data from selected studies. Results about complication events and deaths were pooled in meta-analyses using risk difference (RD) as the outcome statistic. Heterogeneity across trials and possible publication bias were statistically measured. Subgroup analyses (post hoc) were conducted to compare results of self-testing versus self-management, low versus high trial quality, trials conducted in the UK versus trials in other countries and industry versus other sponsors. A Markov-type, state-transition model was developed. Stochastic simulations using the model were conducted to investigate uncertainty in estimated model parameters.

RESULTS

In the 16 randomised and eight non-randomised trials selected, patient self-monitoring of oral anticoagulation therapy was found to be more effective than poor-quality usual care provided by family doctors and as effective as good-quality specialised anticoagulation clinics in maintaining the quality of anticoagulation therapy. There was no significant RD of major bleeding events between patient self-monitoring and usual care controls and pooled analyses found that compared with primary care or anticoagulation control (AC) clinics, self-monitoring was statistically significantly associated with fewer thromboembolic events. However, the reduction in complication events and deaths was not consistently associated with the improvement of AC; in some trials this may be due to alternative explanations, including patient education and patient empowerment. Also, the improved AC and the reduction of major complications and deaths by patient self-monitoring were mainly observed in trials conducted outside the UK. According to UK-specific data, for every 100 eligible patients, 24% would agree to conduct self-monitoring, 17 of the 24 patients (70%) could be successfully trained and able to carry out self-monitoring and only 14 of these (80%) would conduct long-term self-monitoring. Seven cost-effectiveness studies were identified and the study that provided the most relevant UK data found that patient self-management was more expensive than current routine care (417 pounds versus 122 pounds per patient-year) and concluded that using a cost-effectiveness threshold of 30,000 pounds per quality-adjusted life-year (QALY) gained, patient self-management does not appear to be cost-effective. De novo modelling for this report found that the incremental cost per QALY gained by patient self-monitoring is 122,365 pounds over 5 years and 63,655 pounds over 10 years. The estimated probability that patient self-monitoring is cost-effective (up to 30,000 pounds/QALY) is 44% over a 10-year period. Wide adoption of patient self-monitoring of anticoagulation therapy would cost the NHS an estimated additional 8-14 million pounds per year.

CONCLUSIONS

For selected and successfully trained patients, self-monitoring is effective and safe for long-term oral anticoagulation therapy. In general, patient self-management (PSM) is unlikely to be more cost-effective than the current specialised anticoagulation clinics in the UK; self-monitoring may enhance the quality of life for some patients who are frequently away from home, who are in employment or education, or those who find it difficult to travel to clinics. Further research is needed into alternative dosing regimes, the clinical effectiveness and cost-effectiveness of patient education and training in long-term oral anticoagulation therapy, UK-relevant cost-effectiveness, the effectiveness of PSM in children, and the potential future developments of near-patient testing devices.