Table 3.

Types of diagnostic imaging methods, site of the tumors, and invasiveness criteria for the imaging and histopathological findings

References	Imaging	Anatomical place of the OSCC (n∘)	Diagnostic criteria of image invasion	Criteria for histological invasiveness
Handschel et al. [15]	CT	Mandible (58)	Three-point scale evaluation of cortical bone erosion. Invasion: periosteal impairment and bone	Three-point classification in relation to the degree of penetration into the cortical bone
		Oral floor(43)
		Tongue(6)
Gu et al. [14]	CT	Tonsils (23)	Interruption or erosion of the peripheral edge with hyper-attenuation of the signal. Four-point scale of bone evaluation. Invasion probably or surely present Substitution of the peripheral signal hyposensitivity with tumor signal intensity in T1 and T2, or substitution of the hyperintense signal with intermediate tumor signal Dark areas corresponding to regions with high absorption of FDG adjacent to cortical bone showing a visible defect in the accumulation of FDG in the cortical or medullary sites of the same region Combined score scale: score of 4 for multiple tests, or a combined score >2. Like above Like above	No distinction was made between the invasion of the cortical or bone marrow. Both were considered positive for invasion.
	MRI	Retromolar trine (8)
	PET/CT	Base of the tongue (6)
	CT+MRI	Oral floor(5)
	CT+PET/CT	Oral area (3)
	MR+PET/CT	Gingiva (1)
	CT+MRI+PET/CT
Hendrikx et al. [8]	CBCT	Retromolar trine(8)	Four-point scale in relation to bone compromise. Positive: slight invasion, obvious invasion Like above Like above	Erosion: bone substituted but without invasion of the medullary spaces, of the mandibular canal and of the parodental ligament. Mandibular invasion: widespread tumor growth within the bone marrow, the root canal and if present in the periodontal ligament space
	Digital PR	Oral floor (9)
	MRI	Lower alveolar flange (3)
Van Cann et al. [9]	CT	Retromolar trine (20) Oral floor (31) Lower alveolar flange (13) Mucous membrane (3)	Absence of cortical bone adjacent to an abnormal soft tissue mass	Bone cortical invasion: bone replacement without invasion of the medullary spaces, the mandibular canal, or the periodontal ligament. Medullary invasion: diffuse growth of the tumor inside the bone marrow, of the root canal and if present in the periodontal ligament space
	MRI	Retromolar trine (20) Oral floor (31) Lower alveolar flange (13) Mucous membrane (3)	Replacement of the peripheral signal hyperintensity with tumor signal intensity in T1 and T2, or substitution of the hyperintense signal with intermediate tumor signal.
	Digital PR	Retromolar trine (20) Oral floor (31) Lower alveolar flange (13) Mucous membrane (3)	n.i
	SPECT		n.i.
Van den Brekel et al. [13]	MRI	Retromolar process (9)	Tumor within the mandible or hyperintensity of the normal medullary signal replaced by an intermediate signal or an inflammatory eaction in T1	Impairment of spongiosa and bone marrow
	CT	Oral floor (20)	Destruction of the external cortical bone and/or bone marrow.
	Digital PR		Three categories: absence of invasion. Minimum erosion. Extended invasion. Invasion: prevalence of bone destruction, replaced by the tumor
Hakim et al. [12]	CT	Mandible(84)	Semi-quantitative scale with three evaluation points of cortical bone invasion. Bone erosion > at half the thickness of the cortical bone. Penetration of the cortical bone. Infiltration of bone marrow	Bone infiltration was established when tumor cells invaded and perforated the cortical bone (pT4a), according to the UICC/TNM classification for malignant tumors.
	CBCT		3-D evaluation of the degree of bone involvement in the three axial, coronal, and sagittal planes, with semi-quantitative scale with three points of assessment of the bone invasion (see above)
	SPECT
Kolk et al. [16]	SPECT/CT	Mandible (50)	Classification of images in five categories. Evident involvement of the periosteum and bone. Probable involvement of the periosteum and bone. Not evident involvement of the periosteum and bone. Probably no periosteal involvement and certainly no mandibular erosion. No periosteal and bone involvement	Histological evaluation was conducted on horizontal sections throughout the tumor contact area using standard stains. The analysis of the vertical sections established the state of resection of the margins inside the bone marrow
	MRI		Like above
	MSCT		Like above

n.i.: no information; UICC: union for international cancer control