Purpose or Case Report: A 9-year-old girl presented with lethargy, fatigue and progressive exertional dyspnea for the last two-three years, and rapid breathing for the past six months. Chest X-ray showed confluent air space opacities in both lungs. Chest computed tomography (CT) scan done outside 3 months previously showed diffuse ground-glass opacities with interstitial thickening suggestive of crazy paving in bilateral lungs. To evaluate the disease progression without the radiation exposure associated with another CT scan, magnetic resonance imaging (MRI) was performed. It showed diffuse hyperintense areas bilaterally on T2 turbo spin echo and MultiVane XD sequences, indicative of ground-glass changes. Radiologically, a possibility of pulmonary alveolar proteinosis (PAP) was given. Subsequently, bronchoalveolar lavage and lung biopsy confirmed PAP.

In PAP, the phospholipidoproteinaceous material which deposits within the alveoli presents with longer T2 relaxation time, and longer or equal T1 relaxation time which results in hyperintense signal, as seen in the index case. With the recent advances in lung MRI, short-duration protocols are able to give diagnostic information similar to CT in children [1-2], thereby emerging as an attractive radiation-free modality. MRI can demonstrate the findings of PAP similar to CT, and may be relatively better than CT in picking up the parenchymal changes associated with PAP [3].

To conclude, MRI may serve as an attractive radiation-free modality in diagnosing PAP in children and evaluating the lung changes over time.

REFERENCES:
1. Sodhi KS, Khandelwal N, Saxena AK, et al. Rapid lung MRI in children with pulmonary infections: Time to change our diagnostic algorithms. J Magn Reson Imaging. 2016;43:1196-206.
2. Sodhi KS, Khandelwal N, Saxena AK, et al. Rapid lung MRI - paradigm shift in evaluation of febrile neutropenia in children with leukemia: a pilot study. Leuk Lymphoma. 2016;57:70-5.
3. Luo J, Yang D, Xiao E, et al. Lung MRI at 3T: comparison of CT and MRI in initial evaluation of pulmonary alveolar proteinosis. Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2013;38:1160-6.
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