What type of MRI (Magnetic Resonance Imaging) should be ordered for a patient with instability of the left hip and catching sensation, with no abnormalities found on X-ray (Radiograph)?

From the Guidelines

For a patient with left hip instability and catching sensation with normal X-rays, an MRI arthrogram of the left hip would be the most appropriate imaging study. This is based on the most recent and highest quality study available, which suggests that MRI arthrography is superior to other imaging modalities for evaluating labral tears and other intra-articular abnormalities that may cause hip instability and catching sensations 1. The arthrogram technique involves injecting contrast material directly into the hip joint before the scan, which enhances visualization of the labrum, cartilage, and other intra-articular structures.

Some key points to consider when ordering an MRI arthrogram for this patient include:

• The procedure is typically performed under fluoroscopic guidance by a radiologist who injects the contrast, followed by the MRI scan 1.
• Patients should be informed that they may experience temporary increased discomfort after the injection.
• Standard MRI without contrast may miss subtle labral pathology or loose bodies within the joint that could explain the patient's symptoms.
• The imaging choice is justified because hip instability with mechanical symptoms like catching often involves soft tissue structures that are better visualized with contrast enhancement, particularly the acetabular labrum and capsular structures that maintain hip stability but don't appear on plain radiographs 1.

It's also important to note that other imaging modalities, such as ultrasound or CT arthrography, may not provide the same level of detail and accuracy as MRI arthrography for evaluating labral tears and other intra-articular abnormalities 1. Therefore, an MRI arthrogram of the left hip is the most appropriate imaging study for this patient, and it should be performed with contrast enhancement to provide the best possible visualization of the intra-articular structures.

From the Research

MRI Options for Hip Instability and Catching Sensation

• For a patient with instability of the left hip and catching sensation, with no abnormalities found on X-ray, an MRI (Magnetic Resonance Imaging) can be valuable in diagnosing occult osseous abnormalities and periarticular soft tissue disorders 2.
• MR arthrography (MRA) is an effective means of hip evaluation, especially for labral tears, as it extends the capabilities of conventional MRI by separating intra-articular structures and outlining abnormalities 2, 3.
• Indirect MR arthrography appears to be an effective means of hip evaluation for labral tears, with a higher detection rate compared to conventional MRI 3.
• Noncontrast MRI of the hip, using an optimized protocol, can also noninvasively identify labral and chondral pathology, which may facilitate deciding which patients warrant surgical intervention 4.

Recommended MRI Sequences

• Unilateral sagittal turbo spin-echo proton density fat-suppressed, axial turbo spin-echo T2 fat-saturated, and coronal turbo spin-echo proton density fat-saturated images can be used to evaluate the hip 3.
• Whole-pelvis coronal T1 and STIR sequences can also be performed to evaluate the hip and surrounding structures 3.
• Gadolinium-enhanced fat-saturated T1 sequences can be obtained in three planes to evaluate the labrum and other intra-articular structures 3.

Diagnostic Correlation with Arthroscopy

• MR arthrography has been shown to have a high diagnostic correlation with arthroscopy in acetabular labral and cartilage lesions of the hip 3.
• Noncontrast MRI of the hip has also been shown to have good agreement with surgical grading of articular cartilage defects and acetabular labral pathology 4.