Validation of MRI for Volumetric Quantification of Atelectasis in the Perioperative Period: An Experimental Study in Swine

Abstract

Background: Impairment of pulmonary aeration is a frequent postoperative complication that is associated with adverse outcome. Diagnosis and quantification of impaired pulmonary aeration by CT scan is limited due to concern for exposure to ionizing radiation. Magnetic resonance imaging (MRI) represents a potential radiation-free alternative for this use. We undertook an experimental study to validate the use of MRI to quantify pulmonary aeration impairment. Methods: Ten large white pigs were studied before intubation, after intubation, 2 h after non-protective mechanical ventilation and after intra-tracheal negative pressure suction to induce atelectasis. A lung CT scan immediately followed by a lung MRI were performed at all four time points. On the 40 CT images lung volumes corresponding to non-aerated, poorly aerated, normally aerated, and overinflated voxels were measured based on their radiodensity. Similarly, on the 40 MRI images lung volumes corresponding to non-aerated and aerated voxels were measured based on their signal intensity. The correlation between non-aerated lung by MRI vs., CT scans, and with PaO 2 /FiO 2 measured at each of the four time points was assessed with the Pearson’ correlation coefficient, bias and limits of agreement. Results: Pearson correlation coefficient, bias and limits of agreements between the CT non-aerated lung volumes and MRI abnormal lung volumes were 0.88, -16 ml, and (-108, 77), respectively. Pearson correlation coefficient between PaO 2 /FiO 2 and abnormal lung volumes measured with MRI was -0.60. Conclusion: In a preclinical swine model, quantitative measurements of pulmonary atelectasis by MRI-imaging are well correlated with the gold standard, i.e., densitometric scan CT measurements.

A novel, automated, quantification of abnormal lung parenchyma in patients with COVID-19 infection: Initial description of feasibility and association with clinical outcome

“…Our results suggest that automating a volume measurement of ground-glass opacity and normal lung volumes is feasible and has an excellent correlation with the classical segmentation method. The correlation coefficient, bias and limits of agreement of our automated measurement method compared to the gold standard semi-automated segmentation method were similar to analog validations studies focusing on image-based lung volumes measurement [18] , [25] . This automated measurement is also correlated with clinical outcome in the next 7 days after CT image acquisition.…”

“…As previously described [18] , a semi-automated lung volume measurements was performed remotely (e.g. at home) by trained medical imaging technologists using VP-lab© software (Visible Patient©, Strasbourg, France) (use at distance of the software from Visible Patient Server).…”

“…The sample size was set at 40 consistent with a previously published experimental study focusing on similar endpoints [18] .…”

“…Being widely available, CT is broadly used as a routine diagnostic tool in addition to RT-PCR sampling [16] . CT is used in some patients to qualitatively quantify [17] , [18] the extent of lung parenchymal lesions.…”

Changes in lung aeration and respiratory function after open abdominal surgery: A quantitative magnetic resonance imaging study

“…More recently, quantitative magnetic resonance imaging (MRI) has been proposed as a radiation-free alternative to CT, 13,14 potentially suitable for studies in the perioperative setting. 15 The aim of this study was to describe, using quantitative MRI, the changes in lung aeration after major abdominal surgery and the diagnostic accuracy of SpO 2 and FVC to detect postoperative atelectasis.…”