Magnetic resonance imaging of interstitial lung diseases: A state-of-the-art review

Novelties in Imaging of Thoracic Sarcoidosis

“…Over the last few years many studies have assessed the utility of MRI in the evaluation of lung parenchyma, particularly in interstitial lung diseases (ILDs) [ 20 , 22 , 23 , 24 ].…”

“…After localizer sequences, a T2-weighted sequence (generally on coronal plane) should be acquired using single shot techniques (i.e., half-Fourier acquisition single-shot turbo spin echo imaging, HASTE, by Siemens or single-shot fast spin echo, SS-FSE, by General Electric—GE). T2-weighted imaging is extremely helpful in the assessment of ILDs, in which inflammatory and fibrotic changes are typically interspersed; inflammatory areas, generally manifesting as acute alveolitis, are associated with high water content within the tissues and, therefore, appear as areas of high signal intensity, whereas fibrotic-predominant lesions will be hypointense [ 23 ]. T2-weighted HASTE sequence can demonstrate also other kind of pulmonary infiltrates, which will appear as hyperintense areas contrasting against the dark background of the normal lung parenchyma, including mucus and fluid accumulation and inflammatory bronchial thickening.…”

“…T2-weighted HASTE sequence can demonstrate also other kind of pulmonary infiltrates, which will appear as hyperintense areas contrasting against the dark background of the normal lung parenchyma, including mucus and fluid accumulation and inflammatory bronchial thickening. Following T2-HASTE, a T1-weighted sequence (on axial plane) is performed using spoiled three-dimensional (3D) gradient echo sequences (GRE) (i.e., volumetric interpolated breath-hold examination, VIBE, by Siemens or fast acquisition with multiphase elliptical fast gradient echo, FAME, by GE) [ 23 ]. This sequence is particularly suited for mediastinal evaluation and to assess bulky consolidations and large areas of fibrosis in inspiration, and to detect trapped air in expiration [ 8 , 20 ].…”

“…Furthermore, a steady-state free-precession GRE sequence should be acquired (i.e., true fast imaging with steady-state precession, TrueFISP, by Siemens or fast imaging employing steady-state acquisition, FIESTA, by GE), which provides shorter echo and acquisition times, lower sensitivity to motion artifacts and mixed T2/T1 contrast weighting. Besides identification of pulmonary fibrosis, ground-glass opacities, and traction bronchiectasis, TrueFISP—which is “white blood” flow sensitive—demonstrates a great accuracy in detection of pulmonary embolism [ 23 ]. Finally, contrast-enhanced sequences should be included, generally T1-weighted 3D-GRE, to allow a clearer evaluation of vascular and hilar structures, pleura, and solid nodules or masses.…”

“…Contrast-enhanced sequences are also extremely helpful in the evaluation of ILDs; generally, early enhancement is an indicator of active disease, whereas late-enhancement correlates with fibrotic abnormalities. This happens because inflammatory-predominant lesions have an increased extravascular interstitial volume and angiogenesis, which results in an earlier and faster enhancement compared to normal lung interstitium; late-enhancement in fibrosis, instead, might be a result of the destruction of the lung interstitial microvasculature, impairing contrast washout [ 23 ].…”