Detection of Lung Tumors in Mice Using a 1-Tesla Compact Magnetic Resonance Imaging System

Abstract

Due to their small size, lung tumors in rodents are typically investigated using high-field magnetic resonance (MR) systems (4.7 T or higher) to achieve higher signal-to-noise ratios, although low-field MR systems are less sensitive to susceptibility artifacts caused by air in the lung. We investigated the feasibility of detecting lung tumors in living, freely breathing mice with a 1-T compact permanent magnet MR system. In total, 4 mice were used, and MR images of mouse lungs were acquired using a T1-weighted three-dimensional fast low-angle shot sequence without cardiac or respiratory gating. The delineation and size of lung tumors were assessed and compared with histopathological findings. Submillimeter lesions were demonstrated as hyperintense, relative to the surrounding lung parenchyma, and were delineated clearly. Among the 13 lesions validated in histopathological sections, 11 were detected in MR images; the MR detection rate was thus 84.6%. A strong correlation was obtained in size measurements between MR images and histological sections. Thus, a dedicated low-field MR system can be used to detect lung tumors in living mice noninvasively without gating.

A pulmonary metastatic model of murine melanoma assessed by magnetic resonance imaging

“…On the other hand, T2‐weighted image is used to investigate tissue contrast generally associated with an increase in water content. The submillimetre lung lesions in the murine samples were able to be visualized by MRI, and were performed in this study when the primary lesion on the pinna was excised, then again at 4 weeks after resection.…”

Longitudinal, in vivo assessment of invasive pulmonary aspergillosis in mice by computed tomography and magnetic resonance imaging

“…31,32 Despite these challenges, the potential of MRI has motivated several groups to report the successful use of 1 H-MRI for preclinical imaging of lung fibrosis and lung neoplasms. [33][34][35] Recently, more advanced MR sequences were optimized to overcome sensitivity problems of lung MRI, in particular MRI using ultrashort echo times (UTEs) or zero echo times. These novel MR sequences were successfully used for lung fibrosis and emphysema imaging.…”

Analytical dose modeling for preclinical proton irradiation of millimetric targets

“…These three examples represent typical tumor sizes in mice . The proton beam energies are chosen in agreement with existing facilities that can deliver energies compatible with small‐animal irradiation .…”

“…These three examples represent typical tumor sizes in mice. 1,2 The proton beam energies are chosen in agreement with existing facilities that can deliver energies compatible with small-animal irradiation. 5,19,20 For each tested tumor configuration, the energy straggling of the beam is fixed at r E = 150 keV (typical value for 25 MeV cyclotron), with a dose D p = 1 Gy delivered to the tumor volume.…”

“…1 For instance, in mice, a lung tumor measures less than 1.0 mm, and a brain tumor between 2.0 and 4.0 mm, which requires accurate dose calculations with a spatial submillimeter resolution. 2 To achieve high positioning accuracy (<0.025 mm) 6 and spatial resolution (<0.145 mm for mice) 4 when irradiating small-size animal tumors, image-guided irradiation platforms have been developed, both for conventional photon radiotherapy 4 and proton therapy. 5 These platforms led to the development of dedicated tools, including adapted treatment planning systems (TPS) for small-animal irradiation.…”