Fasciculation distribution in a healthy population assessed with diffusion tensor imaging

<p>Fasciculations, a hallmark of motor neuron diseases, also occur in healthy individuals, highlighting the need to understand the intensity and distribution of fasciculations. Motor unit MRI (MUMRI) can assess fasciculations in large volumes but is not widely used. We hypothesize that a more commonly used MRI technique, diffusion tensor imaging (DTI), can also detect fasciculations when corrected for low signal-to-noise ratios and signal variability. We first systematically compared MUMRI and DTI in the upper leg muscles of healthy subjects (n = 5). Second, we retrospectively determined the intensity and distribution of fasciculations in the lower extremity muscles of 30 healthy subjects using DTI (n = 30). DTI and MUMRI showed comparable sensitivity (75%) and precision (80%) to expert reviews. In our healthy cohort, fasciculations were more prevalent in the lower legs than in the upper legs (13.9 ± 11.5% vs. 9.8 ± 6.3%, p = 0.011), particularly in the soleus (9.3 ± 8.1%). This effect persisted after normalizing for muscle volume (7.2 ± 5.1%/dm³ vs. 2.9 ± 1.8%/dm³, p < 0.001). Fasciculations in the lower leg were larger than those in the upper leg (0.81 ± 0.31 cm³ vs. 0.54 ± 0.15 cm³, p < 0.001). Longitudinal analysis showed consistent fasciculation distribution over 8 months (n = 13, ICC = 0.803). In conclusion, muscle DTI detects fasciculations in all lower extremity muscles, enabling retrospective analysis of existing datasets and reducing the need for prospective MUMRI studies if muscle DTI data have already been acquired. </p>

DOI 10.14814/phy2.70247