Advances in Quantitative Imaging of Genetic and Acquired Myopathies: Clinical Applications and Perspectives

Abstract

In the last years, magnetic resonance imaging (MRI) has become fundamental for the diagnosis and monitoring of myopathies given its ability to show the severity and distribution of pathology, to identify specific patterns of damage distribution and to properly interpret a number of genetic variants. The advances in MR techniques and post-processing software solutions have greatly expanded the potential to assess pathological changes in muscle diseases, and more specifically of myopathies; a number of features can be studied and quantified, ranging from composition, architecture, mechanical properties, perfusion, and function, leading to what is known as quantitative MRI (qMRI). Such techniques can effectively provide a variety of information beyond what can be seen and assessed by conventional MR imaging; their development and application in clinical practice can play an important role in the diagnostic process and in assessing disease course and treatment response. In this review, we briefly discuss the current role of muscle MRI in diagnosing muscle diseases and describe in detail the potential and perspectives of the application of advanced qMRI techniques in this field.

Muscle MRI in two SMA patients on nusinersen treatment: A two years follow-up

“…Recent studies have demonstrated the role of DTI in the detection and quantification of muscle fibers fat replacement [ 20 , Table 1 ]; FA is a parameter used to quantify the directional orientation of water molecules within the fibers; FA values are ranged between 0 and 1: in principle, when [ [1] , [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] ] tissues are intact, water is forced to move in a specific direction and the FA value is close to 1; unexpectedly patients with severe fat replacement show positive correlation with FA values and negative correlation with Apparent Diffusion Coefficient (ADC); a possible explanation is the artificial increase of FA values in patients with more than 40–45% fat muscle infiltration [ 25 ]. In our cases DTI showed that nusinersen treatment may have a positive effect on size, length and organization of fiber tracts raising the potential neurogenic rescue even in long-standing chronic SMA patients.…”

“…Furthermore limited data are available on muscle degeneration and neurophysiology over time, and this is often a limiting factor in interpreting the impact of any treatment in these patients. In several neuromuscular disorders, muscle MRI is increasingly used to identify a specific pattern of muscular involvement [ 9 , 10 ], to monitor progression [ 11 ], to quantify the effects of treatment on muscle structure [ 12 ], and in some pharmacological trials as a potential biomarker [ 13 ]. Only a few MRI studies have described the pattern of muscular involvement in the different subtypes of SMA [ [14] , [15] , [16] ].…”

Rimeporide as a first- in-class NHE-1 inhibitor: Results of a phase Ib trial in young patients with Duchenne Muscular Dystrophy

“…There is also clear scientific rationale supporting the concept that NHE-1 could play an important role in several pathophysiological processes involved in DMD. In skeletal muscles of DMD patients, due to the lack of dystrophin, mechanical stress during contraction leads to skeletal and cardiac muscle fibers fragility, tears in the sarcolemma, influx of extracellular Ca2+ [ 15 ], subsequent inflammation and Na + overload [ 16 ], and alkalization [ 17 ]. Na + is presumed to accumulate in dystrophic muscle fibers through microtears and channels leading to enhanced Ca2+ entry through the NCX.…”

Magnetization Transfer Ratio in Lower Limbs of Late Onset Pompe Patients Correlates With Intramuscular Fat Fraction and Muscle Function Tests

“…We also identified a good correlation between muscle FF and muscle MTR value, suggesting that MTR values decrease in relation to progressive loss of muscle fibers that are replaced by fatty tissue. Quantitative muscle MRI is progressively being implemented in the follow-up of patients with neuromuscular diseases, including Pompe disease, in clinical trials and natural history studies (11)(12)(13). Dixon imaging allows calculating the FF, which is the amount of skeletal muscle replaced by fatty tissue.…”