<prompt> Which one of the following is the investigation of choice for evaluation of suspected Pehe;s disease?Plain X-rayUltrasonography USComputed Tomography CTMagnetic Resonance Imaging MRI  <response>: 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 