Muscle MRI characteristic pattern for late-onset TK2 deficiency diagnosis

Area of Science:

• Biomedical Imaging
• Neuromuscular Disorders
• Mitochondrial Genetics

Background:

• TK2 deficiency (TK2d) is a rare mitochondrial myopathy causing progressive muscle weakness.
• Prognosis is poor due to respiratory failure, emphasizing the need for early diagnosis.
• A specific treatment for TK2d is under development, increasing diagnostic urgency.

Purpose of the Study:

• To assess the diagnostic utility of lower limb muscle MRI in adult patients with TK2d.
• To identify characteristic MRI patterns associated with TK2d.
• To differentiate TK2d MRI findings from other myopathies with similar clinical presentations.

Main Methods:

• Analysis of lower limb muscle MRI fat replacement patterns in 45 genetically confirmed mitochondrial myopathy patients.
• Inclusion of 16 patients with TK2d, 9 with other nuclear gene mutations, 10 with mtDNA deletions, and 10 with mtDNA point mutations.
• Comparison of TK2d MRI patterns with those of non-mitochondrial genetic myopathies.

Main Results:

• A consistent MRI pattern was observed in TK2d patients, involving the gluteus maximus, gastrocnemius medialis, and sartorius muscles.
• This specific pattern in TK2d patients differs from radiological findings in other myopathies with similar clinical features.
• The study analyzed the largest cohort of muscle MRIs in mitochondrial myopathy patients to date.

Conclusions:

• Lower limb muscle MRI reveals a characteristic and specific pattern of involvement in TK2d.
• This MRI pattern can significantly aid in accelerating the diagnosis of TK2d.
• Early diagnosis through MRI is vital for timely intervention and management of this progressive myopathy.