Phase-Resolved Functional Lung MRI for Pulmonary Ventilation and Perfusion (V/Q) Assessment

The main aim of our research is to visualize and quantify lung ventilation and perfusion dynamically over the whole cardiac cycle and over the whole ventilation cycle in order to detect lung disease early and to quantify treatment response, and in the end be able to help with prognostication of patients with lung disease. Recent developments introduced sequences for 3D isotropic volume reconstruction of ventilation cycles, yielding higher spatial resolution than 2D protocols, creating a 3D PREFUL variant. This advancement, while significant, lacks perfusion insights, position the 3D and 2D protocols as a complementary tools for a more holistic lung function analysis.

I think in the recent year we were quite successful with PREFUL MRI in various clinical scenarios. I would like to point out three. First of all, COPD.

I think we could show very convincingly that after inhaler therapy, improved ventilation takes place, but we also could show that at the same time we see improved pulmonary parenchymal perfusion together with an improved VQ match. Secondly, lung transplantation. It is important to predict lung transplant loss and see how your patients are doing, and PREFUL was able to exactly do that.

PREFUL could predict future transplant loss due to allograft dysfunction due to chronic lung transplant rejection. And last but not least, in children, I think it's very important there, because they're often noncompliant doing lung function tests, and here we could see and quantify treatment response in children with CF after treatment. Overall, I think PREFUL MRI is on a very good way transitioning from bench to bedside.

Our protocol, phase-resolved functional lung MRI allows free breathing imaging without additional hardware, contrast media or radiation, using universally available MRI sequences. It offers retrospective image sorting, providing a detailed analysis of ventilation and perfusion dynamics. This combination of accessibility, non-invasiveness, and comprehensive diagnostic capabilities sets it apart from other techniques.

In the future, our laboratory will focus on reducing scan times and enhancing image quality through optimized sequence protocols, designs, and AI-driven reconstruction techniques. We are also dedicated to developing, refining, and validating new quantitative biomarkers, including quantitative perfusion, pulse wave velocity, and pulmonary arterial pressure measurements. To begin, educate the patients about the procedures'magnetic properties and risks upon their arrival.

Instruct patients to remove all personal metallic items. Then, orient the patient headfirst in a supine position on the 0.55 T, 1.5 T, or 3T system. Provide hearing protection, an emergency bell, padding, and a blanket for safety and comfort.

Next, position a multichannel flex coil just beneath the patient's chin to ensure optimal coil sensitivity across all lung areas and secure the coil's placement without hindering the patient's breathing. Then, instruct the patient to close their eyes, and mark the center of the lung with the MR laser. After aligning the lung center at the ISIS center, scan the initial localizers to establish a general orientation, and conduct a transversal morphological scan to identify the tracheal bifurcation.

Then, anchor the first coronal slice at the tracheal bifurcation as a landmark to ensure reproducibility. Depending on the scan protocol, either capture three slices spaced at 100%of slice to slice distance, or acquire multiple slices covering the entire lung at 20%or 33%distance. Next, retrieve the acquired phase-resolved functional lung MRI images.

Select the main path and click process to separate DICOM images, based on slice location and temporal sequence using header information. Select either ANTs B-spline SyN with cross correlation metric, or Forsberg polynomial expansion with elastic and fluid regularization as the registration algorithm. The functional lung imaging maps of a 30-year-old healthy female showed a homogeneous distribution of the parenchymal values and low defect percentages, while those of a 60-year-old male COPD patient showed a heterogeneous distribution of the parenchymal values and high defect percentages.