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Table 1 Sample demographics, study design, tumor type, treatment type, method and timing of data collection of the selected papers

From: MRI findings of radiation-induced changes of masticatory muscles: a systematic review

  Pajari et al., 1996[17] Chong et al. 2000[16] Ariji et al. 2002[14] Bhatia et al. 2009[15]
Study design Case report Retrospective study Case Report Retrospective study (1998–2005)
How information was obtained • Clinical and MRI assessment. • Review of clinical and MRI records. • Clinical and MRI assessment. • Review of clinical and MRI records.
Population • N = 1 • N = 5 (only 3 had MRI) • N = 1 • N = 35
Characteristics • Sex: F • Sex: 4 M, 1 F. • Sex: M • Sex: 30 M, 5 F.
Mean age • Age: 9 years. • Age: mean 54 years, range 17 to 74. • Age: 57 years. • Age: mean 51 years, range 35 to 75.
Tumor type • Rhabdomyosarcoma • Squamous cell carcinoma. • Squamous cell carcinoma. • Nasopharyngeal carcinoma
  • Adenocarcinoma.   
  • Mucoepidermoid and oncocytic carcinomas of parotid.   
Treatment type • Radiotherapy • Radiotherapy • Radiotherapy • Radiotherapy
• Chemotherapy   • Chemotherapy  
Tumor site Right auricular region Soft palate Nasopharynx Nasopharynx
  Nasopharynx   
  Submandibular and parotid glands   
Time between radiotherapy completion and MRI assessment • 18 months • Mean 4.4 years (range 1 to 8 years) • 8 months • Mean 6.7 years (range 1.3 to 15.2 years)
Radiation dose • 50 Gy • 60 to 69 Gy • 75.8 Gy • Not reported
MRI findings (T1-W): (T1-W, T2-W, contrast-enhanced): (T1-W, T2-W, contrast-enhanced): (T1-W, T2-W, contrast-enhanced):
   Pre-radiotherapy:  
• Ipsilateral masseter muscle atrophy. • Bone marrow of involved portion of mandible showed homogenous low signal intensity in T1-W, high signal intensity in T2-W, and diffuse intense enhancement with contrast medium. • Tumor mass in left nasal cavity. • 19 patients had abnormal increase in signal intensity of masseter, temporalis, lateral & medial pterygoid muscles
• Ipsilateral condylar head flattening. • All patients had cortical disruption of the mandible. • Ipsilateral size reduction in the masseter, lateral & medial pterygoid muscles. .• 16 patients had only mild signal intensity changes in masticatory muscles. However, they had different abnormalities such as (nerve injury, TMJ deformity, osteoradionecrosis, fibrosis & inflammation).
• Contralateral condylar head osteophyte. • 3 patients had ipsilateral increase of signal intensity of masseter, lateral and medial pterygoid muscles adjacent to the osseous abnormalities. • T1-W revealed increase in signal intensity of the lateral pterygoid muscle due to fatty infiltration.  
• Bilateral normal TMJ articular disc morphology. • 2 patients had prominent mass-like thickening of masseter, lateral and medial pterygoid muscles. • T2-W revealed increase of signal intensity of the masseter, lateral & medial pterygoid, temporalis and mylohyoid muscles.  
• Bilateral normal signal intensity of the TMJ articular surfaces & mandibular ramus.   • Contrast enhanced image showed tumor invasion along the mandibular division of trigeminal nerve.  
   Post- radiotherapy:  
   • Remarkable increase in the (T2-W) signal intensity of the lateral pterygoid muscle.  
Radiographic findings Panoramic radiograph: CT with IV administration of contrast medium: ----------- ------------
• Normal TMJ articular disc morphology. • All patients had ipsilateral abnormal enhancement of the masseter, lateral and medial pterygoid muscles adjacent to the osseous abnormalities.   
• Root development stopped at ipsilateral molars and premolars. • 4 patients had prominent mass-like thickening of masseter, lateral and medial pterygoid muscles.   
• Ipsilateral shorter ramus and larger gonial angle. • All patients had mandibular osseous abnormality, disorganization & loss of trabeculation of the spongiosa of the mandible.   
  • 1 patient suffered ipsilateral mandibular fistula.   
  • 1 patient suffered ipsilateral mandibular pathologic fracture.   
Clinical findings • Tenderness of ipsilateral TMJ capsule, masseter, lateral & medial pterygoid and posterior digastric muscles. • All patient suffered ipsilateral facial pain and swilling. ----------- • Restricted vertical mouth opening range (3–25 mm).
• Restricted vertical mouth opening (23mm). • 1 patient suffered ipsilateral numbness, tingling & dysesthesia a long the inferior alveolar nerve.   
• Normal lateral mouth movement. • 3 patients suffered trismus.   
• Higher EMG activity of ipsilateral masseter & temporalis muscles in all movements. • All patients suffered osteoradionecrosis (4 ipsilateral &1 contralateral).   
• Normal salivary flow. • 1 patient suffered ipsilateral mandibular fistula.   
• Ipsilateral superficial dental decay, heavy plaque accumulation and gingivitis. • 1 patient suffered ipsilateral mandibular pathologic fracture.