A super-resolution proof of concept in a cycloidal coded aperture miniature mass spectrometer.

RATIONALE: Higher resolution in fieldable mass spectrometers (MS) is desirable in space flight applications to enable resolving isobaric interferences at m/z < 60 u. Resolution in portable cycloidal MS coupled with array detectors could be improved by reducing the slit width and/or by reducing the width of the detector pixels. However, these solutions are expensive and can result in reduced sensitivity. In this paper, we demonstrate high-resolution spectral reconstruction in a cycloidal coded aperture miniature mass spectrometer (C-CAMMS) without changing the slit or detector pixel sizes using a class of signal processing techniques called super-resolution (SR). METHODS: We developed an SR reconstruction algorithm using a sampling SR approach whereby a set of spatially shifted low-resolution measurements are reconstructed into a higher-resolution spectrum. This algorithm was applied to experimental data collected using the C-CAMMS prototype. It was then applied to synthetic data with additive noise, system response variation, and spatial shift nonuniformity to investigate the source of reconstruction artifacts in the experimental data. RESULTS: Experimental results using two ½ pixel shifted spectra resulted in a resolution of ¾ pixel full width at half maximum (FWHM) at m/z = 28 u. This resolution is equivalent to 0.013 u, six times better than the resolution previously published at m/z = 28 for N2 + using C-CAMMS. However, the reconstructed spectra exhibited some artifacts. The results of the synthetic data study indicate that the artifacts are most likely caused by the system response variation. CONCLUSIONS: This paper demonstrates super-resolution spectral reconstruction in C-CAMMS without changing the slit or detector pixel sizes using a sampling SR approach. With improvements, this technique could be used to resolve isobaric interferences in a portable cycloidal MS for space flight applications.

Abdominal wall necrotising fasciitis due to dislodged percutaneous endoscopic gastrostomy tube.

Accessing the stomach via a percutaneous endoscopic gastrostomy (PEG) tube is the preferred (and sometimes the only) method for providing enteral nutritional support in disabled patients. However, it is associated with serious and potentially lethal complications which must be completely recognised by physicians, by nurses and especially by radiologists. Abdominal wall necrotising fasciitis of a dislodged or leaking PEG tube could be a lethal complication. We present a case of a 74-year-old bed bound woman who was admitted to our hospital with fever and abdominal pain. On presentation, the patient's temperature was 36°C and laboratory tests showed leucocytosis. Physical examination revealed extensive redness of the abdominal wall, diffuse tenderness of the abdomen and yellowish discharge around the gastrostomy.