Imaging of chest disorders is mainly achieved by using computed tomography. This is especially the case for detection, morphologic assessment and followup of pulmonary nodules. A positron emission tomography (PET) /CT may be additionally required for lung nodule management in some conditions including a size greater than 8 mm with morphologic or growing characteristics suspicious of malignancy. Magnetic Resonance Imaging (MRI) represents however an interesting alternative diagnostic radiation-free method, in particular owing to the recent development of sequences dedicated to lung parenchyma analysis. A major limitation remains the control of respiratory artefacts. High Frequency non-invasive ventilation, HF-NIV, has the potential to allow chest stabilization and is currently used in the department of radio-oncology at the Lausanne University Hospital. It has been recently applied to perform MRI and PET examinations at end inspiration during an "apnea " generated by the system. Continuous periods of respiratory stabilization of several minutes at end-inspiration are thus obtained, allowing prolonged MR and PET acquisitions with improvement of image quality as observed in our preliminary studies (Beigelman-Aubry et al., Prior et al.). Interestingly, the lung volume explored by using this ventilation technique is similar to that of CT studies, conversely to respiratory gated MR sequences which are currently performed at end-expiration, this potentially generating underevaluation of lung disorders especially at lung bases. The present project aims to determine the impact of HF-NIV in the management of patients with pulmonary nodule(s). After a first step of optimization of acquisition parameters of HF-NIV-MR in healthy volunteers, the performances of MRI and PET/CT (when required) under this ventilation technique will be compared to the current method(s) of reference in cases of pulmonary nodule(s) (CT scan and PET when required) and histological data when available. All MRI and PET/CT (when required) acquisitions will be performed without the ventilation technique, as used in current practice, and with it. The project was completed with an amendment to investigate MRI under continuous positive airway pressure (CPAP). The MR-CPAP combination will be evaluated with optimized parameters in healthy volunteers and compared to free-breathing acquisitions without any device.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
DIAGNOSTIC
Masking
SINGLE
Enrollment
40
MRI data will be acquired with the use of HF-NIV.
PET data will be acquired with the use of HF-NIV.
MRI data will be acquired without the use of any device as a reference.
PET/CT data will be acquired in inspiratory breath hold without the use of HF-NIV.
MRI data will be acquired with the use of CPAP.
University Hospitals
Lausanne, Switzerland
Image quality, step 1: Healthy volunteers, sharpness of vessels
Sharpness of interfaces of vessels will be scored on a discrete scale as 1=blurred; 2=intermediate; 3=sharp. This will determine the adequate choice of MR sequences and parameters.
Time frame: day 1
Sensitivity for nodule detection, step 2: Patients (arm A)
Determine whether HF-NIV-MR allows a better detection (higher sensitivity) of the presence of pulmonary nodules compared with conventional MR. CT will be used as gold standard.
Time frame: day 1
Sensitivity for nodule characterization, step 2: Patients (arm B)
Determine whether sensitivity of the apparent diffusion coefficient (ADC) value obtained with HF-NIV-MR (diffusion sequence) to characterize nodules is higher than the sensitivity obtained with conventional MRI. Histological data will be used as gold standard when available.
Time frame: day 1
Assessment of CPAP-MR, step 1 bis: Healthy volunteers
Determine whether CPAP-MR has an additional value compared with MR. Image quality of the CPAP-MR acquisition will be evaluated similarly to the methodology of step 1 and compared to the gold standard MR acquisition (free-breathing without any device).
Time frame: day 1
Image quality, step 1: Healthy volunteers, sharpness of bronchi
Sharpness of interfaces of bronchi will be scored on a discrete scale as 1=blurred; 2=intermediate; 3=sharp.
Time frame: day 1
Image quality, step 1: Healthy volunteers, sharpness of fissures
Sharpness of interfaces of fissures will be scored on a discrete scale as 1=blurred; 2=intermediate; 3=sharp.
Time frame: day 1
Image quality, step 1: Healthy volunteers, visibility of vessels
Modified criteria of Ohno (Ohno et al.) will be used and vessels will be scored as follows 0=non visible; 1=depicted at a lobar level; 2=depicted at a segmental level; 3=depicted at a sub-segmental level; 4=depicted at a sub-sub segmental level; 5=depicted beyond the sub-subsegmental level.
Time frame: day 1
Image quality, step 1: Healthy volunteers, visibility of bronchi
Modified criteria of Ohno (Ohno et al.) will be used and bronchi will be scored as follows 0=non visible; 1=depicted at a lobar level; 2=depicted at a segmental level; 3=depicted at a sub-segmental level; 4=depicted at a sub-sub segmental level; 5=depicted beyond the sub-subsegmental level.
Time frame: day 1
Image quality, step 1: Healthy volunteers, visibility of fissures
Fissures will be scored as follows 0=non visible; 1=visible.
Time frame: day 1
Nodule dimensions
The variable of interest will be the volumetry of each nodule detected which will be evaluated by using dedicated software. This will be compared with volumetric assessment by using CT performed less than 1 month before the MR examination, at best the same day. Two-Dimensional measurements (long axis, mean of the long and short diameter) will also be used, in accordance with usual recommendations \[MacMahon et al.\].
Time frame: day 1
MR-PET fusion
Fusion of MR acquisitions and PET under HF-NIV should be obtained with a good accuracy. The correspondence will be evaluated with a fiducial anatomical structures technique, as if acquisitions were done on a PET-MR scanner.
Time frame: day 1
Correlation of diffusion MRI with metabolic activity
The correlation between ADC (diffusion coefficient) and metabolic activity in HF-NIV-PET/CT, will be compared to the one obtained without HF-NIV.
Time frame: day 1
PET/CT stabilization assessment
The PET/CT image stabilization methods will compared and the best one will be determined (electronic respiratory-gating during the normal free-breathing PET/CT, a single short PET/CT apnea (\<30 seconds) and the HF-NIV-PET/CT acquisition.
Time frame: day 1
Correlation with ex-vivo nodule volume
When applicable, the volume of lesions measured on imaging studies will be compared to the volume measured ex-vivo following surgical resection.
Time frame: day 1
Tolerance CPAP-MR, step 1 bis: Healthy volunteers
Subject subjective tolerance to CPAP-MR will be scored on a 5 points discrete scale as follows: 0=no additional discomfort, 1=minor discomfort, 2=moderate discomfort, 3=high discomfort, 4=extreme discomfort (same methodology as for steps 1 and 2).
Time frame: day 1
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