This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pediatric orthopedics, Subject name: Orthopaedics
Which one of the following is the investigation of choice for evaluation of suspected Pehe&;s disease? 
Select and explain. 
A. Plain X-ray, B. Ultrasonography (US), C. Computed Tomography (CT), D. Magnetic Resonance Imaging (MRI)
D: Magnetic Resonance Imaging (MRI)
Answer: D: Magnetic Resonance Imaging (MRI) 
Explanation: MRI is helpful to assess the area of infarction & femoral head contour . *radiographic assessment is necessary to determine the progress of the disease ,sphericity of femoral head , epiphyseal extrusion or collapse & response to treatment . *salter extrusion angle helps to assess femoral head extrusion . *ahrography is useful in the early resorptive stage of the disease *radionuclide bone scan - used to detect potential form of pehes disease. REF:textbook of ohopedics, John ebnezer, 4th edition ,pg.no.414