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Abstract Diffuse alveolar hemorrhage (DAH) is an uncommon but life-threatening condition. Although DAH must be distinguished from other lung diseases, no specific computed tomography (CT) signs of DAH have been reported. This study aimed to evaluate the diagnostic value of “hyperdense consolidation” CT sign. We retrospectively evaluated non-contrast CT findings of 25 DAH patients and age- (≤ 2 years) and sex-matched controls with symptoms of dyspnea and hypoxemia. Two radiologists compared the two groups for the presence of hyperdense consolidation signs in lung parenchyma, defined as consolidation that visually contains areas with higher density than the aorta in the specific narrow window setting (window level = 35 Hounsfield units [HU], width = 80 HU) with a mediastinal filter. The sensitivity, specificity, positive- and negative-predictive values of the hyperdense consolidation sign for detection of DAH were 32.0%, 100%, 100%, and 59.5% with perfect interobserver agreement (к = 1.00). The hyperdense consolidation sign was found to be a highly specific sign for DAH.

Abstract Background and purpose Synthetic MR imaging (SyMRI) allows the reconstruction of various contrast images, including double inversion recovery (DIR), from a single scan. This study aimed to investigate the advantages of SyMRI by comparing synthetic DIR images with synthetic T2-weighted fluid-attenuated inversion recovery (T2W-FLAIR) and conventional DIR images. Materials and methods We retrospectively reviewed the imaging data of 100 consecutive patients who underwent brain MRI between December 2018 and March 2019. Synthetic DIR, T2W-FLAIR, T1-weighted, and phase-sensitive inversion recovery (PSIR) images were generated from SyMRI data. For synthetic DIR, the two inversion times required to suppress white matter and cerebrospinal fluid (CSF) were manually determined by two radiologists. Quantitative analysis was performed by manually tracing the region of interest (ROI) at the sites of the lesion, white matter, and CSF. Synthetic DIR, synthetic T2W-FLAIR, and conventional DIR images were compared on the basis of using the gray matter-to-white matter, lesion-to-white matter, and lesion-to-CSF contrast-to-noise ratios. Results The two radiologists showed no differences in setting inversion time (TI) values, and their evaluations showed excellent interobserver agreement. The mean signal intensities obtained with synthetic DIR were significantly higher than those obtained with synthetic T2W-FLAIR and conventional DIR. Conclusion Synthetic DIR images showed a higher contrast than synthetic T2WFLAIR and conventional DIR images.