From the Guidelines
The best imaging modality to investigate a plunging ranula is MRI orbits, face, and neck without and with IV contrast, due to its superior soft tissue contrast resolution and ability to delineate the soft tissue extent of the lesion. This recommendation is based on the most recent and highest quality study available, which emphasizes the importance of MRI in the initial staging of major salivary gland cancer and its ability to overcome the limitations of other imaging modalities such as US and CECT 1. The use of MRI allows for the detection of perineural tumor spread, deep-tissue extension, and marrow involvement, which are key components in the assessment of a plunging ranula.
Some of the key benefits of MRI in this context include:
- Superior soft tissue contrast resolution, which enables better visualization of the ranula's extent and its relationship to surrounding structures in the neck and floor of the mouth
- Ability to detect perineural tumor spread, deep-tissue extension, and marrow involvement
- Accurate depiction of the anatomy of the floor of the mouth, which is imperative in preoperative staging
- Higher sensitivity and specificity for differentiating between benign and malignant tumors compared to other imaging modalities
While other imaging modalities such as CT and US may also be useful in the assessment of a plunging ranula, MRI is the preferred modality due to its superior soft tissue contrast resolution and ability to provide a more comprehensive evaluation of the lesion. The addition of advanced MRI techniques such as diffusion-weighted imaging and perfusion imaging may further improve the ability of MRI to distinguish benign from malignant lesions, although these tools are not consistently used in routine clinical practice 1.
From the Research
Imaging Options for Plunging Ranula
The best imaging options to investigate a plunging ranula include:
- Magnetic Resonance Imaging (MRI) 2, 3, 4: MRI is a valuable method for correctly diagnosing plunging ranula, as it can reveal the true extent of the lesion and its relationship to surrounding structures.
- High-resolution ultrasound 5: Ultrasound is recommended as the preferred examination for plunging ranula, particularly in young patients, due to its cost-effectiveness, accessibility, and excellent correlation with surgical findings.
- Other imaging techniques, such as ultrasonography, may also be used to confirm the diagnosis and monitor the regression of the cyst after surgery 3.
Characteristics of Plunging Ranula on Imaging
On imaging, plunging ranulas typically appear as:
- Well-defined, homogeneous masses with low signal on T1- and high signal on T2-weighted images 4
- Cystic lesions in the submandibular space, often extending into adjacent spaces, such as the sublingual space or parapharyngeal space 4
- A "tail sign" may be present, indicating extension into the sublingual space 4
Diagnostic Considerations
When diagnosing a plunging ranula, it is essential to consider the characteristic signs on imaging and to differentiate it from other cystic masses in the floor of the mouth and/or suprahyoid portion of the neck 4, 6.