Purpose To accelerate 19F‐MR imaging of inhaled perfluoropropane using compressed sensing methods, and to optimize critical scan acquisition parameters for assessment of lung ventilation properties. Methods Simulations were performed to determine optimal acquisition parameters for maximal perfluoropropane signal‐to‐noise ratio (SNR) in human lungs for a spoiled gradient echo sequence. Optimized parameters were subsequently employed for 19F‐MRI of inhaled perfluoropropane in a cohort of 11 healthy participants using a 3.0 T scanner. The impact of 1.8×, 2.4×, and 3.0× undersampling ratios on 19F‐MRI acquisitions was evaluated, using both retrospective and prospective compressed sensing methods. Results 3D spoiled gradient echo 19F‐MR ventilation images were acquired at 1‐cm isotropic resolution within a single breath hold. Mean SNR was 11.7 ± 4.1 for scans acquired within a single breath hold (duration = 18 s). Acquisition of 19F‐MRI scans at shorter scan durations (4.5 s) was also demonstrated as feasible. Application of both retrospective (n = 8) and prospective (n = 3) compressed sensing methods demonstrated that 1.8× acceleration had negligible impact on qualitative image appearance, with no statistically significant change in measured lung ventilated volume. Acceleration factors of 2.4× and 3.0× resulted in increasing differences between fully sampled and undersampled datasets. Conclusion This study demonstrates methods for determining optimal acquisition parameters for 19F‐MRI of inhaled perfluoropropane and shows significant reduction in scan acquisition times (and thus participant breath hold duration) by use of compressed sensing.
Hepatic hydrothorax (HH) represents a distinct clinical entity within the broader classification of pleural effusion that is associated with significant morbidity and mortality. The median survival of patients with cirrhosis who develop HH is 8-12 months. The diagnosis is typically made in the context of advanced liver disease and ascites, in the absence of underlying cardiopulmonary pathology. A multi-disciplinary approach to management, involving respiratory physicians, hepatologists, and palliative care specialists is crucial to ensuring optimal patientcentered care. However, the majority of accepted therapeutic options are based on expert opinion rather than large, adequately powered randomized controlled trials. In this narrative review, we discuss the epidemiology, pathophysiology, clinical characteristics, and management of HH, highlighting the use of salt restriction and diuretic therapy, porto-systemic shunts, and liver transplantation. We include specific sections focusing on the role of pleural interventions and palliative care, respectively.
Purpose To assess alveolar perfusion by applying dynamic susceptibility contrast MRI to 19F‐MRI of inhaled perfluoropropane (PFP). We hypothesized that passage of gadolinium‐based contrast agent (GBCA) through the pulmonary microvasculature would reduce magnetic susceptibility differences between water and gas components of the lung, elevating the T2∗ of PFP. Methods Lung‐representative phantoms were constructed of aqueous PFP‐filled foams to characterize the impact of aqueous/gas phase magnetic susceptibility differences on PFP T2∗. Aqueous phase magnetic susceptibility was modulated by addition of different concentrations of GBCA. In vivo studies were performed to measure the impact of intravenously administered GBCA on the T2∗ of inhaled PFP in mice (7.0 Tesla) and in healthy volunteers (3.0 Tesla). Results Perfluoropropane T2∗ was sensitive to modulation of magnetic susceptibility difference between gas and water components of the lung, both in phantom models and in vivo. Negation of aqueous/gas phase magnetic susceptibility difference was achieved in lung‐representative phantoms and in mice, resulting in a ~2 to 3× elevation in PFP T2∗ (3.7 to 8.5 ms and 0.7 to 2.6 ms, respectively). Human studies demonstrated a transient elevation of inhaled PFP T2∗ (1.50 to 1.64 ms) during passage of GBCA bolus through the lung circulation, demonstrating sensitivity to lung perfusion. Conclusion We demonstrate indirect detection of a GBCA in the pulmonary microvasculature via changes to the T2∗ of gas phase PFP within directly adjacent alveoli. This approach holds potential for assessing alveolar perfusion by dynamic susceptibility contrast 19F‐MRI of inhaled PFP, with concurrent assessment of lung ventilation properties, relevant to lung physiology and disease.
Most staff do not enforce trust policy regarding e-cigarette use. This reflects variation in opinion over use, poor awareness of the policy itself and perceived barriers to implementation, including fear of abuse. Addressing these issues through staff education sessions may help successful future implementation.
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