Contemporary Diagnostic Imaging of Oral Squamous Cell Carcinoma - A Review of Literature

Abstract

Oral squamous cell carcinoma (OSCC) is the most common cancer of the oral cavity and constitutes 95% of all cancers of this area. Men are affected twice as commonly as women, primarily if they are over 50 years of age. Forty percent of the lesions are localized in the tongue and 30% in the floor of the oral cavity. OSCC often affects upper and lower gingiva, buccal mucous membrane, the retromolar triangle and the palate. The prognosis is poor and the five-year survival rate ranges from 20% (OSCC in the floor of the mouth) to 60% (OSCC in the alveolar part of the mandible). Treatment is difficult, because of the localization and the invasiveness of the available methods. The diagnosis is made based on a histopathological examination of a biopsy sample. The low detection rate of early oral SCC is a considerable clinical issue. Although the oral cavity can be easily examined, in the majority of cases oral SCC is diagnosed in its late stages. It is difficult to diagnose metastases in local lymph nodes and distant organs, which is important for planning the scope of resection and further treatment, graft implantation, and differentiation between reactive and metastatic lymph nodes as well as between disease recurrence and scars or adverse reactions after surgery or radiation therapy. Imaging studies are performed as part of the routine work-up in oral SCC. However, it is difficult to interpret the results at the early stages of the disease. The following imaging methods are used - dental radiographs, panoramic radiographs, magnetic resonance imaging with diffusion-weighted and dynamic sequences, perfusion computed tomography, cone beam computed tomography, single-photon emission computed tomography, hybrid methods (PET/CT, PET/MRI, SPECT/CT) and ultrasound. Some important clinical problems can be resolved with the use of novel modalities such as MRI with ADC sequences and PET. The aim of this article is to describe oral squamous cell carcinoma as it appears in different imaging methods considering both their advantages and limitations.

Keywords: Carcinoma, Squamous Cell; Cone-Beam Computed Tomography; Diagnostic Imaging; Diffusion Magnetic Resonance Imaging; Perfusion Imaging.

Figure 1

Radiography of the mandible. Discrete radiolucency in bone tissue on the right side.

Figure 2

Panoramic radiograph. Bowl-shaped bone defect in the left part of the mandibular body, approximately 5.9 cm in length. The osteolytic lesion reaches the alveolus of the lower left canine that had lost distal bony support.

Figure 3

Contrast-enhanced computed tomography. There is a tumor in the tongue (1 cm in diameter) on the right (T1 stadium). On the histopathological examination, it was diagnosed as a highly differentiated oral squamous cell carcinoma (G1) (A) axial view (B) coronal view (C) sagittal view.

Figure 4

Contrast-enhanced computed tomography. There is a tumor in the tongue (3.5×2.8×1.6 cm) on the right (T2 stadium). On the histopathological examination, it was diagnosed as an oral squamous cell carcinoma with moderate/low degree of differentiation (G2/3) (A) axial view (B) coronal view (C) sagittal view.

Figure 5

Magnetic resonance imaging after contrast administration (A) T1 sequence, axial view, tumor in the tongue (3.5×3.3 cm) on the right (T2 stadium). On the histopathological examination, it was diagnosed as an oral squamous cell carcinoma with moderate/low degree of differentiation (G2/3). (B) T2, axial view, tumor in the tongue (4.5×2.2 cm) on the right (T2 stadium). On the histopathological examination, it was diagnosed as an oral squamous cell carcinoma with moderate/low degree of differentiation (G2/3). (C) T2, coronal view. There is a tumor in the tongue (3.5×3.3 cm) on the right (T2 stadium). On the histopathological examination, it was diagnosed as an oral squamous cell carcinoma with moderate/low degree of differentiation (G2/3).

Figure 6

Magnetic resonance imaging after contrast administration (A) FAT SAT, T1 sequence, axial view. Tumor (4.9×2.9 cm, T3 stadium) with a decreased diffusion coefficient. (B) Apparent-diffusion-coefficient map (ADC map), axial view (mean value of 1034.86×10⁶ mm²/s).

Figure 7

¹⁸F-FDG PET, sagittal view. Tumor of the tongue infiltrating the mandible (T4a stadium). On the histopathological examination, it was diagnosed as an oral squamous cell carcinoma with low degree of differentiation (G3).

Figure 8

(A) ¹⁸F-FDG PET. Tumor of the tongue infiltrating the mandible (T4a stadium). On the histopathological examination, it was diagnosed as an oral squamous cell carcinoma with low degree of differentiation (G3). (A) axial view (B) sagittal view.