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Radiation-induced plexopathy and fibrosis. Is magnetic resonance imaging the adequate diagnostic tool?
Ulrike Hoeller1, Michael Bonacker, Amira Bajrovic
1Department of Radiotherapy and Radiooncology, Center of Radiology, University Hospital Eppendorf, Hamburg, Germany. ulrike.hoeller@vivantes.de
Purpose:
To investigate magnetic resonance imaging (MRI) features of radiation-induced plexopathy (RIP) and radiation-induced fibrosis frequently associated with RIP.
Patients And Methods:
Seven patients with late radiation sequelae in the supraclavicular region were examined with MRI after a median interval of 7 years (range, 5-18 years) following radiotherapy and 4-7 years after the onset of RIP. Four patients had RIP plus severe soft-tissue fibrosis, two RIP without soft-tissue fibrosis (n = 2/6), and one patient fibrosis without RIP. Patients underwent surgery of breast cancer (n = 6) or chest wall relapse (n = 1) and radiotherapy to the supraclavicular fossa with cobalt with an anterior portal in fractions of 1.7-2.6 Gy to 43-51.6 Gy in 3 cm depth. All patients were relapse-free at the time of MRI. Fibrosis and RIP were scored clinically (RTOG classification). Fibrosis of the supraclavicular and/or axillary region was marked in three and mild in two patients. RIP was mild, marked and severe in two patients each. MRI was performed with a 1.5-T unit including coronal STIR, coronal and transversal T2-weighted, transversal T1-weighted and fat-saturated post-contrast (gadolinium-DTPA) spin echo sequences.
Results:
The brachial plexus appeared normal in all patients, but subtle changes of adjoining tissue (slight, linear signal intensity in T2-weighted images or contrast enhancement surrounding the plexus) were detected in patients with RIP (n = 4/6) and the patient without RIP (n = 1). However, alterations of the soft tissue (marked signal intensity in T2-weighted sequences) correlated well with the clinical degree of fibrosis and were restricted to areas of marked to severe fibrosis (n = 3/3).
Conclusion:
Reliable MRI signs of RIP could not be identified. The severity of fibrosis closely corresponded to MRI features. The role of MRI in the diagnostic work-up of RIP is, therefore, the exclusion of tumor relapse.
Insights
Magnetic resonance imaging (MRI) did not reveal reliable signs of radiation-induced plexopathy (RIP). However, MRI accurately showed the severity of associated radiation-induced fibrosis, aiding in excluding tumor recurrence.
Area of Science:
- Radiology
- Oncology
- Neurology
Background:
- Radiation therapy for breast cancer and chest wall relapses can cause late sequelae.
- Radiation-induced plexopathy (RIP) and fibrosis are common complications affecting the brachial plexus and surrounding tissues.
Purpose of the Study:
- To investigate magnetic resonance imaging (MRI) features differentiating radiation-induced plexopathy (RIP) from radiation-induced fibrosis.
- To assess the utility of MRI in diagnosing RIP and fibrosis after radiotherapy.
Main Methods:
- Seven patients with late radiation sequelae underwent 1.5-T MRI, including T1, T2, STIR, and post-contrast sequences.
- Clinical assessment (RTOG classification) of RIP and fibrosis severity was performed.
- MRI findings were correlated with clinical scores.
Main Results:
- No definitive MRI signs of RIP were identified in the brachial plexus.
- Subtle changes in adjoining tissues were observed in patients with RIP.
- MRI alterations in soft tissues correlated strongly with the clinical severity of fibrosis.
Conclusions:
- Reliable MRI features for diagnosing RIP are lacking.
- MRI is effective in assessing the severity of radiation-induced fibrosis.
- The primary role of MRI in this context is to exclude tumor relapse.
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