Quantitative assessment of skeletal muscle degeneration in patients with myotonic dystrophy type 1 using MRI

Abstract

Purpose: To identify MRI biomarkers that could be used to follow disease progression and therapeutic efficacy in one individual muscle in patients with myotonic dystrophy type 1 (DM1). Materials and Methods:Lower limb MRI and maximal ankle dorsiflexor strength assessment, using a hand-held dynamometer, were performed in 19 DM1 patients and 6 control subjects. The volume of residual muscle tissue of Tibialis Anterior (TA) muscle was chosen as an index for muscle atrophy, and the T2-relaxation-time of the residual muscle tissue was measured to evaluate edema-like lesions. The fat-to-water ratio was assessed using threepoint Dixon images to quantify fat infiltration in the entire muscle.Results: The intra-observer variability of MRI indices ($5.2% for the residual muscle tissue volume and 2.5% for the fat-to-water ratio) was lower than that of the dorsiflexor torque measurement ($11.5%). A high correlation (r ¼ 0.91) was found between maximal ankle dorsiflexor strength and residual TA muscle tissue volume in DM1 patients. Increases in the fat-to-water ratio and T2-relaxation-time were associated with a decrease in maximal ankle dorsiflexor strength.Conclusion: MRI appears as a noninvasive method which can be used to follow disease progression and therapeutic efficacy.

Characteristic MRI findings of upper limb muscle involvement in myotonic dystrophy type 1

“…Several studies have demonstrated lower limb muscle involvement in DM1 patients [10][11][12][13]; however, the detailed distribution of upper limb muscle involvement has not been reported previously.…”

Skeletal muscle quantitative nuclear magnetic resonance imaging and spectroscopy as an outcome measure for clinical trials (part II)

“…Как использовать получаемые биомаркеры с учетом их полезности при выявлении даже минимальных изменений в результате терапев-тического вмешательства на малых выборках больных? Поскольку они не зависят от субъективной оценки состояния и имеют высокую воспроизводимость, боль-шинство количественных МРТ-показателей -лучшие кандидаты для подтверждения эффекта и мониторин-га результатов терапии [67,68]. Данный вывод основан на предположении о том, что терапевтическое веще-ство будет вызывать одинаковую степень изменений при всех возможных методах оценки результатов, что, однако, не соответствует действительности.…”

Reproducibility, and age, body-weight and gender dependency of candidate skeletal muscle MRI outcome measures in healthy volunteers

“…Quantitative MRI can objectively measure these changes: on T 2 relaxometry muscle T 2 is elevated in myotonic dystrophy [10], Duchenne muscular dystrophy [11], juvenile dermatomyositis [6] and amyotrophic lateral sclerosis [12], while skeletal muscle magnetisation transfer ratio (MTR) is decreased in limb girdle muscular dystrophy [13] and Charcot-Marie-Tooth disease [14]. Muscle fat content has been quantified by T 1 -relaxometry [15], proton spectroscopy ( 1 H-MRS) [16–19], T 2 relaxation modelling [20–22] and chemical-shift based Dixon fat-water separation [23] providing maps of the proportion of fat to water, or “fat fraction” (FF) [10, 22, 24–26].…”