Feasibility study of a novel portable digital radiography system modified for fluoroscopy in the neonatal intensive care unit.

BACKGROUND: A portable radiographic system capable of fluoroscopic imaging in the neonatal intensive care unit (NICU) potentially benefits critically ill neonates by eliminating the need to transport them to a fluoroscopy suite. OBJECTIVE: To evaluate whether a portable bedside fluoroscopy system in the NICU can deliver comparable image quality at a similar dose rate to a standard system in a fluoroscopy suite. MATERIALS AND METHODS: In phase A, 20 patients <3 years of age and scheduled to undergo upper gastrointestinal series (upper GI) or voiding cystourethrograms (VCUG) in the radiology fluoroscopy suite were recruited to evaluate a portable fluoroscopic unit. A modified portable radiographic system with a cassette-sized detector and an in-room fluoroscopy system were sequentially used in the same examination. Four radiologists compared the image quality of 20 images from each system using the Radlex score (1-4) for five image quality attributes. The radiation dose rates for the portable and in-suite systems were collected. In phase B, fluoroscopy studies were performed in 5 neonates in the NICU and compared to the 20 previous neonatal studies performed in the department. Clinical workflow, examination time, fluoroscopy time, scattered radiation dose and patient radiation dose were evaluated. RESULTS: In phase A, average dose rates for in-room and portable systems were equivalent, (0.322 mGy/min and 0.320 mGy/min, respectively). Reader-averaged Radlex scores for in-room and portable systems were statistically significantly greater (P<0.05) for all attributes on the portable system except for image contrast. In phase B, scattered radiation from the average fluoroscopy time (26 s) was equivalent to the scattered radiation of 2.6 portable neonatal chest radiographs. Procedure time and diagnostic quality were deemed equivalent. The average dose rate in the NICU with the portable system was 0.21 mGy/min compared to 0.29 mGy/min for the in-room system. CONCLUSION: The portable fluoroscopy unit is capable of providing comparable image quality at equivalent dose levels to an in-room system for neonates with minimal risks to the staff and other patients in the NICU.

Inhibition of Smooth Muscle ß-Catenin Hinders Neointima Formation After Vascular Injury.

OBJECTIVE: Smooth muscle cells (SMCs) contribute to neointima formation after vascular injury. Although ß-catenin expression is induced after injury, whether its function is essential in SMCs for neointimal growth is unknown. Moreover, although inhibitors of ß-catenin have been developed, their effects on SMC growth have not been tested. We assessed the requirement for SMC ß-catenin in short-term vascular homeostasis and in response to arterial injury and investigated the effects of ß-catenin inhibitors on vascular SMC growth. APPROACH AND RESULTS: We used an inducible, conditional genetic deletion of ß-catenin in SMCs of adult mice. Uninjured arteries from adult mice lacking SMC ß-catenin were indistinguishable from controls in terms of structure and SMC marker gene expression. After carotid artery ligation, however, vessels from mice lacking SMC ß-catenin developed smaller neointimas, with lower neointimal cell proliferation and increased apoptosis. SMCs lacking ß-catenin showed decreased mRNA expression of Mmp2, Mmp9, Sphk1, and S1pr1 (genes that promote neointima formation), higher levels of Jag1 and Gja1 (genes that inhibit neointima formation), decreased Mmp2 protein expression and secretion, and reduced cell invasion in vitro. Moreover, ß-catenin inhibitors PKF118-310 and ICG-001 limited growth of mouse and human vascular SMCs in a dose-dependent manner. CONCLUSIONS: SMC ß-catenin is dispensable for maintenance of the structure and state of differentiation of uninjured adult arteries, but is required for neointima formation after vascular injury. Pharmacological ß-catenin inhibitors hinder growth of human vascular SMCs. Thus, inhibiting ß-catenin has potential as a therapy to limit SMC accumulation and vascular obstruction.