Kiara A. Bowers

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.

Testosterone is the canonical growth factor of prostate cancer but can paradoxically suppress its growth when present at supraphysiological levels. We have previously demonstrated that the cyclical administration of supraphysiological androgen (SPA), termed bipolar androgen therapy (BAT), can result in tumor regression and clinical benefit for patients with castration-resistant prostate cancer. However, predictors and mechanisms of response and resistance have been ill defined. Here, we show that growth inhibition of prostate cancer models by SPA required high androgen receptor (AR) activity and were driven in part by downregulation of MYC. Using matched sequential patient biopsies, we show that high pretreatment AR activity predicted downregulation of MYC, improved clinical response, and prolonged progression-free and overall survival for patients on BAT. BAT induced strong downregulation of AR in all patients, which is shown to be a primary mechanism of acquired resistance to SPA. Acquired resistance was overcome by alternating SPA with the AR inhibitor enzalutamide, which induced adaptive upregulation of AR and resensitized prostate cancer to SPA. This work identifies high AR activity as a predictive biomarker of response to BAT and supports a treatment paradigm for prostate cancer involving alternating between AR inhibition and activation.