Longitudinal changes in COVID-19 clinical measures and correlation with the extent of CT lung abnormalities.

Rationale: To assess the longitudinal changes and relationships of clinical measures and extent of CT lung abnormalities in COVID-19. Methods: 81 patients with COVID-19 were prospectively enrolled and followed until discharge. CT scores were quantified on a basis of a CT scoring system where each lung was divided into 3 zones: upper (above the carina), middle, and lower (below the inferior pulmonary vein) zones; each zone was evaluated for percentage of lung involvement on a scale of 0-4 (0, 0%; 1, 0-24%; 2, 25% - 49%; 3, 50% -74%; 4, >74%).Temporal trends of CT scores and the laboratory parameters characteristic of COVID-19 were analyzed. Correlations between the two were determined at three milestones (initial presentation, worst CT manifestation, and recovery finding before discharge). Their correlations with duration to worst CT manifestation and discharge from symptom onset were evaluated. Results: CT scores peaked during illness days 6-11 (median: 5), and stayed steady. C-reactive protein and lactate dehydrogenase increased, peaked on illness days 6-8 and 8-11 (mean: 23.5 mg/L, 259.9 U/L), and gradually declined. Continual decrease and increase were observed in hemoglobin and lymphocyte count, respectively. Albumin reduced and remained at low levels with a nadir on illness days 12-15 (36.6 g/L). Both initial (r = 0.58, 0.64, p < 0.05) and worst CT scores (r = 0.47, 0.65, p < 0.05) were correlated with C-reactive protein and lactate dehydrogenase; and CT scores before discharge, only with albumin (r = -0.41, p < 0.05). Duration to worst CT manifestation was associated with initial and worst CT scores (r = 0.33, 0.29, p < 0.05). No parameters were related to timespan to discharge. Conclusion: Our results illustrated the temporal changes of characteristic clinical measures and extent of CT lung abnormalities in COVID-19. CT scores correlated with some important laboratory parameters, and might serve as prognostic factors.

A uniformity correction method to reduce scan time for 7T sodium imaging of brain tumors.

BACKGROUND AND PURPOSE: Sodium imaging shows great potential for the characterization of brain tumors. Intensity correction is required but the additional scan time is costly. Recent developments can halve the time but were optimized in normal brains and may not be applicable in brain tumor imaging. We aim to develop an individualized uniformity correction for sodium imaging optimized for brain tumor patients that reduces scan time but provides high-resolution images for clinical practice. METHODS: Two-, 4-, and 6-mm iso-cubic voxel resolution birdcage coil images were used to calculate the 2-mm iso-cubic voxel individual sensitivity maps in healthy subjects (n = 3). Cut profiles were compared to determine the optimal approach. In addition, a 3-dimensional phantom was developed to test a generalized uniformity correction approach in both healthy subjects (n = 3) and tumor patients (n = 3). RESULTS: The cut profiles showed that the average correlation coefficient between 2- and 4-mm birdcage image correction results was r = .9937, and r = .9876 for 2- and 6-mm birdcage images. The correlation result between individual map correction and phantom map correction was r = .9817. CONCLUSION: The 4 mm birdcage coil image provided the optimal approach for both as a compromise between the time-savings effect and image quality. This method allows for a 2-mm iso-cubic voxel resolution clinical sodium scan within 12 minutes. We also presented prescanned phantom sensitivity map results, which were designed to cover all patient head sizes. This approach provides an alternative solution in more time-sensitive cases.