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Purpose: This study aimed to develop a 3D MRI technique to assess lung ventilation in free‐breathing and without the administration of contrast agent. Methods: A 3D‐UTE sequence with a koosh ball trajectory was developed for a 3 Tesla scanner. An oversampled k‐space was acquired, and the direct current signal from the k‐space center was used as a navigator to sort the acquired data into 8 individual breathing phases. Gradient delays were corrected, and iterative SENSE was used to reconstruct the individual timeframes. Subsequently, the signal changes caused by motion were eliminated using a 3D image registration technique, and ventilation‐weighted maps were created by analyzing the signal changes in the lung tissue. Six healthy volunteers and 1 patient with lung cancer were scanned with the new 3D‐UTE and the standard 2D technique. Image quality and quantitative ventilation values were compared between both methods. Results: UTE‐based self‐gated noncontrast‐enhanced functional lung (SENCEFUL) MRI provided a time‐resolved reconstruction of the breathing motion, with a 49% increase of the SNR. Ventilation quantification for healthy subjects was in statistical agreement with 2D‐SENCEFUL and the literature, with a mean value of 0.11 ± 0.08 mL/mL for the whole lung. UTE‐SENCEFUL was able to visualize and quantify ventilation deficits in a patient with lung tumor that were not properly depicted by 2D‐SENCEFUL. Conclusion: UTE‐SENCEFUL represents a robust MRI method to assess both morphological and functional information of the lungs in 3D. When compared to the 2D approach, 3D‐UTE offered ventilation maps with higher resolution, improved SNR, and reduced ventilation artifacts. [ABSTRACT FROM AUTHOR]

Summary: Functional F-fluoride PET demonstrated an inverse relationship between the activity of arterial mineral deposition and regional bone metabolism. While bone metabolism decreases with age, the activity of arterial mineral deposition increases. Introduction: The extent of arterial calcification increases with age, whereas bone mineral density decreases, evidencing a well-known inverse correlation on morphological basis. The aim of this study was to evaluate the functional relationship between the activity of arterial mineral deposition and regional bone metabolism as assessed by F-sodium fluoride (NaF) PET/CT. Methods: Three hundred four subjects were examined by F-NaF PET/CT. Tracer accumulation in the femoral arteries was analyzed both qualitatively and semiquantitatively by measuring the blood-pool-corrected standardized uptake value (target-to-background ratio). Uptake was compared with cardiovascular risk factors (RFs), calcified plaque burden, and regional bone metabolism as assessed by PET/CT. Results: The activity of arterial mineral deposition significantly increased with age ( p < 0.001), whereas regional bone metabolism significantly decreased ( p < 0.001). There was a significant inverse correlation between bone metabolism and arterial mineral deposition (unadjusted, p < 0.001); that association was not significant ( p = 0.79) when controlled for age and other RFs. Both high activity of arterial mineral deposition and low bone metabolism were significantly associated with cardiovascular events and other RFs. Conclusion: F-NaF PET/CT provides a tool to visualize and quantify the activity of arterial mineral deposition and regional bone metabolism. In this study, we observed an inverse correlation between the activity of arterial mineral deposition and regional bone metabolism. While the activity of arterial mineral deposition significantly increases with age, regional bone metabolism decreases. [ABSTRACT FROM AUTHOR]

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Purpose: To implement and validate an algorithm to determine the statistical errors in self-gated non-contrast-enhanced functional lung imaging., Methods: A bootstrapping residuals approach to determine the error in quantitative functional lung imaging is proposed. Precision and accuracy of the median error over the lungs, as well as reproducibility of the approach were investigated in 7 volunteers. The algorithm was additionally applied to data acquired in a patient with cystic fibrosis., Results: The obtained bootstrapping error maps appear comparable to the error maps determined from repeated measurements, and median absolute error values for both methods show comparable median errors when reducing the number of averages. In a volunteer in whom 10 consecutive measurements were carried out, the median functional parameters were ventilation = 0.22 mL gas/mL lung tissue, perfusion amplitude = 0.028, perfusion timing = -82 ms, whereas precision and accuracy of the median error were below 3.2 × 10 -3  mL gas/mL lung for ventilation tissue, 4.4 × 10 -4 for perfusion amplitude, and 11 ms for perfusion timing. In the measurement of the patient, low errors in areas with reduced ventilation support the assessment as real defects., Conclusion: Using a bootstrapping residuals method, the error of functional lung MRI could be determined without the need for repeated measurements. The error values can be determined reproducibly and can be used as a future means of quality control for functional lung MRI., (© 2024 The Author(s). Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)