Feasibility of Quantifying the Mechanical Properties of Lung Parenchyma in a Small-Animal Model Using 1H Magnetic Resonance Elastography (MRE)

Purpose: To evaluate the feasibility of spatially resolving the shear modulus of lung parenchyma using conventional H-1 magnetic resonance elastography (MRE) imaging techniques in a small animal model. Materials and Methods: A 10-cm diameter transmit-receive radiofrequency coil was modified to include a specimen stage, an MRE pneumatic drum driver, and needle system. M RE was performed on 10 female Sprague-Dawley rats using a 1H spin-echo based MRE imaging sequence with a field of view of 7 cm and slice thickness of 5 mm. Air-filled lungs were imaged at transpulmonary inflation pressures of 5, 10, and 15 cm H2O while fluid-filled lungs were imaged after infusion of 4 mL of normal saline. Results: The average shear modulus of air-filled lungs was 0.840 +/- 0.0524 kPa, 1.07 +/- 0.114 kPa and 1.30 +/- 0.118 kPa at 5, 10, and 15 cm H2O, respectively. Analysis of variance indicated that these population means were statistically significantly different from one another (F-value = 26.279, P = 0.00004). The shear modulus of the fluid-filled lungs was 1.65 +/- 0.360 kPa. Conclusion: It is feasible to perform lung MRE in small animals using conventional MR imaging technologies.