Assessment of Lung Structure and Regional Function Using 0.55 T MRI in Patients With Lymphangioleiomyomatosis.

OBJECTIVES: Contemporary lower-field magnetic resonance imaging (MRI) may offer advantages for lung imaging by virtue of the improved field homogeneity. The aim of this study was to evaluate the utility of lower-field MRI for combined morphologic imaging and regional lung function assessment. We evaluate low-field MRI in patients with lymphangioleiomyomatosis (LAM), a rare lung disease associated with parenchymal cysts and respiratory failure. MATERIALS AND METHODS: We performed lung imaging on a prototype low-field (0.55 T) MRI system in 65 patients with LAM. T2-weighted imaging was used for assessment of lung morphology and to derive cyst scores, the percent of lung parenchyma occupied by cysts. Regional lung function was assessed using oxygen-enhanced MRI with breath-held ultrashort echo time imaging and inhaled 100% oxygen as a T1-shortening MR contrast agent. Measurements of percent signal enhancement from oxygen inhalation and percentage of lung with low oxygen enhancement, indicating functional deficits, were correlated with global pulmonary function test measurements taken within 2 days. RESULTS: We were able to image cystic abnormalities using T2-weighted MRI in this patient population and calculate cyst score with strong correlation to computed tomography measurements (R = 0.86, P < 0.0001). Oxygen-enhancement maps demonstrated regional deficits in lung function of patients with LAM. Heterogeneity of oxygen enhancement between cysts was observed within individual patients. The percent low-enhancement regions showed modest, but significant, correlation with FEV1 (R = -0.37, P = 0.007), FEV1/FVC (R = -0.33, P = 0.02), and cyst score (R = 0.40, P = 0.02). The measured arterial blood ΔT1 between normoxia and hyperoxia, used as a surrogate for dissolved oxygen in blood, correlated with DLCO (R = -0.28, P = 0.03). CONCLUSIONS: Using high-performance 0.55 T MRI, we were able to perform simultaneous imaging of pulmonary structure and regional function in patients with LAM.

T2-weighted Lung Imaging Using a 0.55-T MRI System.

PURPOSE: To assess a 0.55-T MRI system for imaging lung disease and to compare image quality with clinical CT scans. MATERIALS AND METHODS: In this prospective study conducted between November 2018 and December 2019, respiratory-triggered T2-weighted turbo spin-echo MRI at 0.55 T was compared with clinical CT scans in 24 participants (mean age, 59 years ± 16 [standard deviation]; 18 women) with common lung abnormalities. MR images were reviewed and scored by experienced readers. Abnormal findings identified with MRI and CT were compared using the Cohen κ statistic. RESULTS: High-quality structural pulmonary MR images were attained with an average acquisition time of 11 minutes ± 3. MRI generated sufficient image quality to robustly detect bronchiectasis (κ = 0.61), consolidative opacities (κ = 1.00), cavitary lesions (κ = 1.00), effusion (κ = 0.64), mucus plug (κ = 0.68), and solid scattered nodularity (κ = 0.82). Diffuse disease, including ground-glass opacities (κ = 0.57) and tree-in-bud nodules (κ = 0.48), were the findings that were most difficult to discern using MRI, with false readings in four of 18 patients for each feature. Nodule size, which was measured independently at CT and MRI, was strongly correlated (R 2 = 0.99) for nodules with a measurement of 10 mm ± 5 (range, 5-23 mm). CONCLUSION: This initial study indicates that high-performance 0.55-T MRI holds promise in the evaluation of common lung disease.Clinical trials registration no. NCT03331380Supplemental material is available for this article. Keywords: MRI, Pulmonary, Technology Assessment© RSNA, 2021.

Implications of the Revised Common Rule for Human Participant Research.

This paper looks at the implications of changes to the regulatory governance of human participant research that can be expected with implementation of the Revised Common Rule (RCR). The RCR refers to revisions of the existing federal regulations that govern the performance of research involving human subjects (ie, clinical research) in the United States and, under certain circumstances, when such research is also performed outside the United States. The term "common" is included because it refers to the fact that these regulations, often referred to as Code of Federal Regulations 46, is the common denominator regulations agreed to across a wide swath of federal agencies.

A clinical assessment of the Mucus Shaver: a device to keep the endotracheal tube free from secretions.

OBJECTIVE: : We evaluated a new device designed to clean the endotracheal tube in mechanically ventilated patients, the Mucus Shaver. DESIGN: : Prospective, randomized trial. SETTING: : University hospital intensive care unit. PATIENTS: : We enrolled 24 patients expected to remain ventilated for >72 hrs. INTERVENTIONS: : The Mucus Shaver is a concentric inflatable catheter for the removal of mucus and secretions from the interior surface of the endotracheal tube. The Mucus Shaver is advanced to the distal endotracheal tube tip, inflated, and subsequently withdrawn over a period of 3-5 secs. Patients were prospectively randomized within 2 hrs of intubation to receive standard endotracheal tube suctioning treatment or standard suctioning plus Mucus Shaver use until extubation. MEASUREMENTS AND MAIN RESULTS: : During the study period, demographic data, recent medical history, adverse events, and staff evaluation of the Mucus Shaver were recorded. At extubation, each endotracheal tube was removed, cultured, and analyzed by scanning electron microscopy. Twelve patients were assigned to the study group and 12 were assigned to the control group. No adverse events related to the use of the Mucus Shaver were observed. At extubation, only one endotracheal tube from the Mucus Shaver group was colonized, whereas in the control group ten endotracheal tubes were colonized (8% vs. 83%; p < .001). Scanning electron microscopy showed little secretions on the endotracheal tubes from the study group, whereas thick bacterial deposits were present on all the endotracheal tubes from the control group (p < .001 by Fisher exact test, using a maximum biofilm thickness of 30 µm as cut-off). The nursing staff was satisfied by the overall safety, feasibility, and efficacy of the Mucus Shaver. CONCLUSIONS: : The Mucus Shaver is a safe, feasible, and efficient device for endotracheal tube cleaning in the clinical setting. The Mucus Shaver is helpful in preventing endotracheal tube colonization by potentially harmful microorganisms.

Lymphangioleiomyomatosis: correlation of qualitative and quantitative thin-section CT with pulmonary function tests and assessment of dependence on pleurodesis.

PURPOSE: To explore the relationship between findings at thin-section computed tomography (CT) and pulmonary function tests in lymphangioleiomyomatosis (LAM) and to evaluate the influence of pleurodesis on this relation and the effectiveness of quantitative versus qualitative CT in the assessment of disease severity. MATERIALS AND METHODS: Thirty-seven patients with LAM (17 with pleurodesis) underwent CT and pulmonary function tests. The severity of pulmonary cystic involvement was graded qualitatively by two independent readers and measured quantitatively at CT with a thresholding technique. Relationships between findings at CT and pulmonary function tests and the influence of pleurodesis on these findings were assessed with regression analysis and analysis of covariance. RESULTS: Qualitative ratings had good agreement between observers (kappa = 0.75). Quantitative CT had good repeatability and showed significant correlation with the percent predicted forced expiratory volume in 1 second (FEV(1)%) (r = 0.67, P <.001), percent predicted diffusing capacity of lung for carbon monoxide (DLCO%) (r = 0.48, P <.005), percent predicted ratio of residual volume to total lung capacity (RV/TLC%) (r = -0.65, P <.001), and percent predicted TLC (r = 0.34, P <.04). Quantitative CT results were somewhat better than qualitative CT results. The standard error of the FEV(1)% for the quantitative CT was about 85% of that for the qualitative CT. Pleurodesis had no statistically significant effect on the slope of the regression line between quantitative CT findings, FEV(1)%, and DLCO% (corrected for alveolar volume). The slope between quantitative CT and RV/TLC% was significantly (P =.044) more negative in patients with pleurodesis. CONCLUSION: Qualitative and quantitative CT findings correlate with pulmonary dysfunction over a wide range of disease severity in patients with LAM. Pleurodesis influences the relationship between CT measurements and pulmonary function test results.