Richard B. Schonour

Compared with chest CT, 0.55-T MRI provided comparable diagnostic performance for consolidation and large solid nodules (≥6 mm) but had lower sensitivity for small solid nodules (<6 mm), ground-glass nodules, and emphysema.

Background: Mid-field MRI scans (0.55 T) have gained attention for pulmonary imaging because of reduced susceptibility artifact, but image quality remains variable across patient populations, limiting its clinical adoption. Purpose: To identify technical and clinical factors associated with poor image quality in 0.55 T lung MRI in adults with various pulmonary diseases. Materials and Methods: Adults with major pulmonary disease (eg, infection, pulmonary fibrosis, cancer) who were scheduled for chest CT or PET/CT at a single health care site were prospectively recruited from January to August 2023 to undergo same-day 0.55 T MRI scans. Exclusion criteria included inability to communicate in English, overlapping pulmonary diagnoses already represented, or declining consent. Respiratory-triggered T2-weighted BLADE and T1-weighted UTE sequences were acquired on a Siemens MAGNETOM Free.Max (0.55 T) scanner. Six radiologists independently graded overall image quality (1 = poor, 2 = fine, 3 = excellent). Respiratory metrics were quantified, including tidal depth, respiratory rate, and respiration length. Body mass index (BMI) and body surface area were calculated. One-way analysis of variance was used to test the association between these factors and image quality. Interreader agreement was assessed using Fleiss kappa and the intraclass correlation coefficient. Results: Twenty-eight participants (mean age, 59 years ± 19; 17 women) were evaluated. Fibrotic interstitial lung disease was linked to degraded image quality. Deeper tidal depth (P = .04), longer respiration length (P = .002), and higher BMI (P = 0.02) were significant predictors of degradation on univariate analysis. Respiratory rate and body surface area were not significantly associated (P > .05). Conclusion: This preliminary study suggests that BMI, pulmonary fibrosis, and deep/slow breathing patterns may be associated with degraded respiratory triggered 0.55 T lung MRI. If confirmed in larger, more diverse cohorts, these findings could help identify patients at risk for lower quality imaging and inform strategies to optimize image quality in clinical practice.

Ontogenetic shifts in venom occur in many snakes but establishing their nature as gradual or discrete processes required additional study. We profiled shifts in venom expression from the neonate to adult sizes of two rattlesnake species, the eastern diamondback and the timber rattlesnake. We used serial sampling and venom chromatographic profiling to test if ontogenetic change occurs gradually or discretely. We found evidence for gradual shifts in overall venom composition in six of eight snakes, which sometimes spanned more than two years. Most chromatographic peaks shift gradually, but one quarter shift in a discrete fashion. Analysis of published diet data showed gradual shifts in overall diet composition across the range of body sizes attained by our eight study animals, while the shifts in abundance of different prey classes varied in form from gradual to discrete. Testosterone concentrations were correlated with the change in venom protein composition, but the relationship is not strong enough to suggest causation. Venom research employing simple juvenile versus adult size thresholds may be failing to account for continuous variation in venom composition lifespan. Our results imply that venom shifts represent adaptive matches to dietary shifts and highlight venom for studies of alternative gene regulatory mechanisms.