Imaging Guidelines for Hip Replacement Surgery

Introduction to Imaging Modalities

MRI provides superior soft tissue contrast compared to CT, allowing for better visualization of soft tissue structures, bone marrow abnormalities, and early osteonecrosis, according to the American College of Radiology 1

The American College of Radiology recommends starting with standard radiographs (X-rays) as the initial imaging modality for all patients, including AP pelvis view, lateral hip view, and frog-leg lateral view if tolerated 1, 2
Radiographs (X-rays) should be the first imaging test ordered for evaluation of a solid mass in the hip, as they provide critical initial information about bone involvement, calcifications, and soft tissue extension, and are a cost-effective screening tool, widely available, and excellent for detecting bone involvement and calcifications, according to the American College of Radiology 1, 2

MRI without contrast is preferred for most musculoskeletal conditions affecting the hip, providing superior assessment of labral tears, tendinopathy, bursitis, bone marrow edema, stress fractures, and osteonecrosis, as stated by the American College of Radiology 1, 2, 3, 4
3T MRI provides statistically better performance compared to 1.5T for preoperative planning, with 3D DP TSE sequences performing better than 3D T1 GRE sequences at both 1.5T and 3T field strengths 1
MRI without contrast is the preferred next step after radiographs, as it provides superior soft tissue contrast, is excellent for characterizing mass composition, and can detect marrow abnormalities, according to the American College of Radiology 2
MRI remains the preferred advanced imaging modality, and contrast enhancement should be considered if infection is suspected, or if there is a need to differentiate solid from cystic components or evaluate tumor vascularity 2

CT should be considered only for specific scenarios where bone detail is critical, such as when radiographs suggest acetabular wall deficiencies or for suspected ceramic liner fracture, as recommended by the American College of Radiology 1
CT may be used for suspected ceramic acetabular liner fracture, as it may be more sensitive than radiographs in these specific cases 1
CT is valuable when radiographs suggest medial, posterior, or superior acetabular wall deficiencies that may require bone grafting or special reconstruction procedures 1

MARS should be used for MRI if evaluating a previously implanted prosthetic hip, to reduce metal artifacts and improve image quality, according to the American College of Radiology 1
If a prosthetic hip is present, radiographs remain first-line, but subsequent MRI should use metal artifact reduction sequences (MARS) to optimize diagnostic accuracy 1
MRI with metal artifact reduction techniques provides superior soft tissue contrast and can detect adverse local tissue reactions, pseudotumors, tendon abnormalities, bursitis, synovitis, and early osteolysis, while avoiding radiation exposure associated with CT 1

Ordering CT without a specific indication when radiographs are normal should be avoided, as well as assuming CT always provides better visualization of hardware, and ordering contrast-enhanced MRI unnecessarily, as stated by the American College of Radiology 1, 2, 3, 4
Failing to obtain appropriate clinical history to guide protocol selection, ordering MRI before appropriate radiographs have been obtained, and assuming that contrast always improves diagnostic yield, are common pitfalls to avoid, according to the American College of Radiology 2, 3, 4
The recommendation against routine CT scans for hip replacement surgery is based on a comprehensive review of available evidence by the American College of Radiology 1
The American College of Radiology explicitly states there is "insufficient evidence to support the use of CT of the hip as the initial imaging procedure in the evaluation of the symptomatic hip" 1