Intestinal wall thickness is neither a specific nor sensitive ultrasound parameter for detecting intestinal inflammation. We hypothesize that mucosal echogenicity, lymphadenomegaly, and secondary findings of the gastrointestinal tract would be more sensitive and specific markers for detecting and differentiating causes of chronic inflammatory bowel disease in dogs. Fifty-six client-owned dogs with chronic diarrhea and 10 control dogs were examined with two-dimensional, gray-scale ultrasound (time 0, 4, and 10 weeks post therapy) and small intestinal mucosal biopsies were performed at the 0- and 4-week time points. The clinical activity was assessed at each time point using the canine inflammatory bowel disease activity index (CIBDAI). Fifty-one dogs had inflammatory infiltration of the duodenal mucosa and were divided into three groups, food-responsive disease, idiopathic inflammatory bowel disease, and protein-losing enteropathy, based on their response to the different treatments and histology. Two different patterns of increased echogenicity of the mucosa were detected: hyperechoic speckles and hyperechoic striations. A normal, hypoechoic bowel mucosa in dogs with chronic diarrhea had a sensitivity of 80% and a specificity of 81% for the diagnosis of food-responsive disease. Hyperechoic striations had a sensitivity of 75% and a specificity of 96% for dogs with protein-losing enteropathy. Hyperechoic speckles were non-specific for diagnosing inflammatory bowel disease. There was a significant relationship between ultrasound score and CIBDAI at t0, but not following therapy. Mucosal echogenicity may be a better parameter for detecting inflammatory bowel disease than bowel wall thickness in dogs with chronic diarrhea.

Perfusion computed tomography (CTP) images tumor angiogenesis and can assess tumor aggressiveness. However, the CTP examinations are dose intensive. This study aimed to optimize a routinely used CTP protocol for the head and neck region in oncology in order to reduce the effective dose to the patient and simultaneously achieve the same image quality.The Alderson phantom was scanned on a GE Revolution CT scanner. A scan with our standard protocol for head and neck cancer patients was used (100kV, 80mAs, 5mm slice thickness and backprojection algorithm) and in seven predefined regions (ROI) the signal to noise ratio (SNR) was measured. For the dose optimized protocol, the tube voltage was lowered and the mAs adaptation protocol was used. To improve image quality different percentage of an adaptive statistical iterative reconstruction (ASiR) was applied. For a better resolution we set the slice thickness to 2.5 mm. The mAs adaption range and the percentage of the ASiR reconstruction were varied until we found a combination with the same median SNR in the seven defined ROIs as for our old protocol. For the old and the optimized protocol dose measurements were performed using 25 LiF-TLDs. Organ doses were calculated and the effective dose was determined based on the weighting factors of ICRP103.The optimized scanning protocol used a voltage of 80kV, a mAs range between 15 and 80, a noise level of 10%, and 50% ASiR reconstruction. The median SNR ratio was slightly better (14% better SNR) with the new protocol. An effective dose of 8 mSv was measured with the original protocol and 4 mSv with the optimized scanning protocol. For organs in the scanning field the dose was reduced by a factor of 2 and outside the field by a factor of 2.2.Advanced reconstruction algorithms allow a significant dose reduction and an improvement of image resolution, while maintaining the image quality.

without apertures. Dose prescriptions for meningiomas and neuromas were 15 and 12 GyRBE, respectively. All meningiomas were superficial and a range shifter (RS) was needed for treatment, while for neuromas it did not. A plan with apertures was optimized for each target volume with same beam direction, cost-function, beam parameters as for the clinical plan without apertures.All plans were optimized on the CTV with Single Field Optimization technique, using min-max robust optimization (2mm setup errors, 3.5% range uncertainties), with a Monte Carlo algorithm and a 1mm grid size. Plans with and without apertures were compared in terms of target coverage (V99, V95, D1) and sparing of the healthy brain tissue within 2cm of the CTV (HBT) (V10, V12, Dmean and D1). In meningiomas, skin sparing was scored via Dmean. Average values were compared with t test and p < 0.05 was considered significant. Results: Results are summarized in table 1. The target coverage was very similar with and without apertures. The distance from CTV to aperture needed to achieve target coverage ranged from 5 to 9 mm. Plans with apertures allowed a reduction in both skin mean dose (range 0.3-2.2 GyRBE) and HBT V10, V12, and mean dose. Considering meningiomas and neuromas separately, the HBT sparing was significant only for meningiomas, where it ranged from 0.9 to 9.1cc for V10 and from 0.4 to 6.0 cc for V12. Conclusion: Apertures are beneficial in intracranial SRS with PBS, in particular for shallow targets such as meningiomas. In deeper lesions where the use of RS is not necessary, such as neuromas, they do not seem to bring an advantage.

No abstract