From the Guidelines
Magnetic Resonance Imaging (MRI) is the best diagnostic tool for discovering osteonecrosis of the jaw (ONJ). When ONJ is suspected, an MRI should be performed promptly as it provides superior soft tissue contrast and can detect early bone marrow changes before they become visible on other imaging modalities. The typical MRI protocol includes T1-weighted, T2-weighted, and contrast-enhanced sequences to evaluate both bone and surrounding soft tissues.
Key Points to Consider
- While panoramic radiographs and computed tomography (CT) scans are often used initially, they may miss early-stage ONJ since they only detect changes after significant bone destruction has occurred.
- MRI is particularly valuable because it can identify areas of altered bone marrow signal intensity, edema, and inflammation that precede frank necrosis.
- For patients with suspected ONJ, especially those with risk factors such as bisphosphonate use, radiation therapy, or dental procedures, early MRI evaluation allows for prompt intervention which may prevent disease progression.
- Clinical examination remains essential and should always accompany imaging studies, as the combination provides the most comprehensive assessment.
- According to the study by 1, the recommended initial evaluation of ORN should include one or more of the following: clinical intraoral examination and/or formal radiographic examination, which supports the use of MRI as a diagnostic tool.
- The study by 1 also recommends utilizing the ClinRad staging system for ORN, which can be used in conjunction with MRI to evaluate the extent of the disease.
- Other studies, such as 1, 1, 1, and 1, provide limited evidence to support the use of CT with or without IV contrast as the initial imaging study for clinically suspected osteonecrosis, further emphasizing the importance of MRI in diagnosing ONJ.
From the Research
Diagnostic Tools for Osteonecrosis of the Jaw
The diagnosis of osteonecrosis of the jaw can be achieved through various imaging techniques, including:
- Conventional radiography
- Computed Tomography (CT)
- Magnetic Resonance Imaging (MRI)
- 99Tc(m)-MDP 3-phase bone scan
- Bone scintigraphy
- SPECT/CT
Comparison of Diagnostic Tools
The studies suggest that:
- 99Tc(m)-MDP 3-phase bone scan is the most sensitive tool to detect osteonecrosis at an early stage 2, 3
- CT scans and MRI are useful in defining the features and extent of osteolytic lesions 2, 4
- Bone scintigraphy shows positive tracer uptake before the development of BRONJ in almost 66% of patients who had these scans before clinical evidence of frank osteonecrosis 3
- SPECT/CT is of particular value in discriminating the osteonecrotic core from nearby hyperactivity due to viable bone 5
Limitations of Diagnostic Tools
The studies also note that:
- Panoramic radiographs have a low detectability of BONJ lesions (54%) compared to MRI and CT scans 4
- MRI and CT scans have problems with the exact assessment of the extent of BONJ lesions in individual patients 4
- Orthopantomography is not able to aid diagnosis of osteonecrosis of the jaw 5
Imaging Findings in BRONJ
The radiographic findings in patients with BRONJ include:
- Osteosclerosis
- Osteolysis
- Dense woven bone
- A thickened lamina dura
- Subperiosteal bone deposition
- Failure of postsurgical remodeling 6