Which condition can MRI be used to assess directly, according to the information provided?

Magnetic resonance imaging (MRI) is a highly sensitive imaging modality that is particularly effective for assessing soft tissues and certain bone conditions. Aseptic necrosis of the femoral head, also known as avascular necrosis, is a condition where there is bone death due to the loss of blood supply. MRI is excellent for visualizing the changes in bone marrow and can detect early changes in the femoral head before they become apparent on X-rays.

In the specific case of aseptic necrosis, MRI can reveal the presence of edema within the bone, changes to the contour of the femoral head, and other marrow alterations that are characteristic of the condition. This capability allows for early diagnosis and management to prevent further joint degeneration.

Other conditions mentioned, such as acute appendicitis, peptic ulcers, and urinary tract infections, are traditionally assessed using ultrasound or CT scans, rather than MRI. Embedded structures like the appendix or signs of inflammation associated with appendicitis are better visualized through CT. Similarly, peptic ulcers are commonly diagnosed with endoscopy or barium studies, while urinary tract infections are assessed via ultrasound or CT for any potential complications, such as abscesses or obstruction. MRI does not serve as the first-line or most effective