Objective Identify appropriate reconstruction modes of Forward-projected model-based Iterative Reconstruction SoluTion (FIRST) in temporal bone computed tomography (CT) and investigate the contribution of spatial resolution and noise to the visual assessment. Methods Sixteen temporal bone CT images were reconstructed. Two blinded radiologists assessed 8 anatomical structures and classified the visual assessment. These visual scores were compared across reconstruction modes among each anatomical structure. Visual scores and contrast-to-noise ratio, noise power spectrum (NPS) at low (NPSLow) and high (NPSHigh) spatial frequencies, and 50% modulation transfer function relationships were evaluated. Results Visual scores differed significantly for the stapedius muscle and osseous spiral lamina, with CARDIAC SHARP, BONE, and LUNG modes for the osseous spiral lamina scoring highest. Visual scores significantly positively correlated with NPSLow, NPSHigh, and 50% modulation transfer function but negatively with contrast-to-noise ratio. Conclusions Modes providing higher spatial resolution and lower noise reduction showed an improved visual assessment of CT images reconstructed with FIRST.

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Metformin, a widely used medicine for diabetes mellitus, is well known to cause lactic acidosis, which may require intensive care, including hemodialysis, especially in severe cases because of the high mortality rate. Because metformin is effectively removed by renal replacement therapy, early initiation of hemodialysis is crucial for metformin overdose. We report a case of a 38-year-old male who was brought to our emergency department (ED) with altered mental status. He subsequently developed severe lactic acidosis with a peak lactate level of 33.4 mmol/L. No clear etiology was identified for these critical conditions at the ED. Although metformin intoxication could not be confirmed at this time, we decided to start hemodialysis immediately. Soon after hemodialysis, blood pH and lactate levels dramatically improved. The patient fully recovered after 9 days of intensive care unit (ICU) stay. Later on, his serum metformin concentration was revealed to be 146 μg/mL and 26 μg/mL at ICU admission and after dialysis at day 3, respectively (therapeutic range, 1–2 μg/mL). Early initiation of hemodialysis might be beneficial for diabetic patients with unexplained severe lactic acidosis despite uncertainties in history of overdose or serum concentration of metformin.