pH-responsive ratiometric photoacoustic imaging of polyaniline nanoparticle-coated needle for targeted cancer biopsy

Cancer microenvironment exhibits lower pH compared to healthy tissues, a characteristic which can be exploited using a pH-responsive needle to increase the accuracy of cancer biopsy. A needle, coated with pH-responsive polyaniline (PANI) nanoparticles (PANI-needle), is developed for the minimally invasive and quantitative pH analysis of tissue based on ratiometric photoacoustic (PA) imaging. The ratiometric PA signal from the PANI-needle within the 850–700 nm wavelength range shows a linear response as pH changes from 7.5 to 6.5. Owing to the high surface area of nanostructured PANI, the PA signal of PANI-needle exhibits a fast and reversible response of less than a few seconds. In a tissue-mimicking hydrogel phantom composed of two regions with different pH, PA ratios of PANI-needle successfully differentiate the local pH. The PANI-needle coupled with ultrasound-guided PA imaging is a promising technology for detection of malignant tissue through quantitative pH analysis during needle biopsy

Midterm change of descending aortic false lumen after repair of acute type I dissection

BACKGROUND: Persistent false lumen in the descending aorta after repair of acute type I dissection adversely affects long-term prognosis. In this study, we investigated changes of the descending aortic false lumen during the midterm postoperative period. METHODS: Postoperative computed tomographic (CT) images of 122 patients who underwent conventional ascending with or without arch replacement for acute type I dissection were reviewed. Patency and width of false lumen and maximal diameter of the aorta were compared between early and last follow-up images. Changes were analyzed separately in the thoracic and abdominal segments. RESULTS: In early CT, thoracic false lumen was patent in 85 patients (69.7%), and abdominal false lumen was patent in 111 patients (91.0%). Among these, the false lumen remained patent after a mean interval of 33.6 months in 69 patients (81.1%) and 105 patients (94.6%), respectively. In 58 patients (47.5%), the descending aorta dilated by 1 cm or more. Dilatation occurred more frequently in the thoracic aorta and in patients with patent or wide false lumens, larger aortic diameter, Marfan syndrome, younger age, and male sex. Meanwhile, shrinkage of thoracic false lumen occurred in 36 patients (29.5%). Such shrinkage occurred in 23 of 24 patients (95.8%) who had thrombosed and narrow false lumens in the thoracic aorta. CONCLUSIONS: Early postoperative characteristics of false lumen were helpful for predicting both dilation and regression. Our data show not only a high incidence of descending aortic dilatation after repair of acute type I dissection, but also shrinkage of thoracic false lumen in some patients. These findings can be used as control data for determining the benefit of more extensive or new surgical approaches