Lumbar disc disease
In symptomatic cases the diagnosis should be confirmed by an MRI scan. However, in cases with slight symptoms, a faster and cheaper CT scan (although it is inferior to MRI scan) may be recommended. While a CT scan can show the bony structures in more detail, an MRI scan can better portray soft tissue.
Occult fracture
The diagnostic performance of MRI in the detection of occult fractures has been shown to be comparable, or better than MDCT. Indeed, while the specificity of both CT and MRI for the diagnosis of fracture can be as high as 100%, the sensitivity was reported to be higher for MRI. The superiority of MRI over any other imaging modality including MDCT for the detection of occult hip fractures is now recognised. For instance, an occult intertrochanteric extension of a greater trochanter fracture can be most effectively appreciated on MRI Moreover, MRI is extremely helpful in detecting associated soft tissue abnormalities, especially ligamentous lesions. MRI is now considered as the standard in this context. However, because of its relative unavailability in emergency settings and high costs, MRI may only be performed in "high risk patients" with negative X-rays. For example, when a hip occult fracture is suspected, patients with reduced baseline mobility and pain on axial compression are considered at risk and, therefore, should be examined by MRI. MRI signs of occult fractures are evident several weeks before radiographic signs appear. In the hip, a limited and cost effective MR protocol, with only T1 weighted () coronal images, may enable a reliable diagnosis or exclusion of occult fracture in very little time, for example, 7 minutes. Typically, a linear hypointensity is observed on T1 W images. MRI is also highly sensitive to marrow abnormalities surrounding the fracture line, which appear as hypointensity on T1 W images and hyperintensity on fluid-sensitive sequences. Such signal changes are thought to be a combination of bone marrow edema, intraosseous haemorrhage, and/or granulation tissue and help to identify even undisplaced fractures. However, in the absence of a history of trauma and linear hypointensities on T1 W images, isolated bone marrow edema may represent other pathologies such as osteoid osteoma and sclerosing osteomyelitis.