Magnetic resonance imaging in the evaluation of idiopathic pulmonary fibrosis: a real possibility, or an attractive challenge?

Influence of flow and susceptibility effects on spin dephasing in lung tissue

PURPOSE

Magnetic resonance imaging (MRI) of the lung can be used for diagnosis and monitoring of interstitial lung disease. Biophysical models of alveolar lung tissue are needed to understand the complex interplay of susceptibility, diffusion, and flow effects, and their influence on magnetic resonance (MR) spin dephasing.

METHODS

In this work, we present a method for modeling the signal decay of lung tissue by utilizing a two-compartment model, which considers the different spin dephasing mechanisms in the alveolar vasculature and interstitial tissue. This allows calculating the magnetization dynamics and the MR lineshape, which can be measured noninvasively using clinical MR scanners.

RESULTS

The accuracy of the method was evaluated using finite element simulations and the experimentally measured lineshapes of a healthy volunteer. In this comparison, the model performs well, indicating that the relevant spin dephasing mechanisms are correctly taken into account.

CONCLUSIONS

The proposed method can be used to estimate the influence of blood flow and alveolar geometry on the MR lineshape of lung tissue.

The role of imaging in the diagnosis and management of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disease lacking a definite etiology, characterized by the nonspecific symptoms of dyspnea and dry cough. Due to its poor prognosis, imaging techniques play an essential role in diagnosing and managing IPF. High resolution computed tomography (HRCT) has been shown to be the most sensitive modality for the diagnosis of pulmonary fibrosis. It is the primary imaging modality used for the assessment and follow-up of patients with IPF. Other not commonly used imaging methods are under research, such as ultrasound, magnetic resonance imaging and positron emission tomography-computed tomography are alternative imaging techniques. This literature review aims to provide a brief overview of the imaging of IPF-related alterations.

Interstitial lung diseases: Imaging contribution to diagnosis and elementary radiological lesions

Interstitial pneumonias comprise a heterogeneous group of disorders in which a multidisciplinary approach is important for accuracy in diagnosis; indeed, one might say, even mandatory. The team of collaborators should include radiologists, because high resolution computed tomography (HRCT) of the thorax is the first, and most of times, the only imaging examination to be prescribed after chest X-ray. Elementary lesions of the interstitium can be accurately described with HRCT, inasmuch as lung windowing with sharp filtering in this technique reproduces the microscopic features of the lung. Guidance of bronchoalveolar lavage and biopsy procedures is also possible with HRCT.

Evaluating disease severity in idiopathic pulmonary fibrosis

Accurate assessment of idiopathic pulmonary fibrosis (IPF) disease severity is integral to the care provided to patients with IPF. However, to date, there are no generally accepted or validated staging systems. There is an abundance of data on using information acquired from physiological, radiological and pathological parameters, in isolation or in combination, to assess disease severity in IPF. Recently, there has been interest in using serum biomarkers and computed tomography-derived quantitative lung fibrosis measures to stage disease severity in IPF. This review will focus on the suggested methods for staging IPF, at baseline and on serial assessment, their strengths and limitations, as well as future developments.