PMC5769210_01
Representative case of increased FDG accumulation: Localized type increasing to extensive type. (A) Pre-treatment FDG-PET computed tomography (CT) shows a right maxillary carcinoma invading the middle cranial fossa. (B and C) Planning CT images. (D) Panoramic radiographic image for the oral examination before radiation therapy (RT). Note the slight uptake of FDG (arrowhead) in the axial view 2 years 2 months after RT (E). Localized type of FDG accumulation (arrowhead) in the axial view 3 years 1 month after RT (F). Extensive-type FDG accumulation (arrowhead) in the axial view 4 years after RT (G). Sequential increase of FDG accumulation (arrowhead) in sagittal views 2 years 2 months after RT (H), 3 years 1 month after RT (I), and 4 years after RT (J). (K) A small fistula with pus discharge (arrowhead) in the left mandibular molar region detected 4 years 5 months after RT. (L) Panoramic radiography shows bone resorption (arrowhead) in the distal area of the left mandibular canine 4 years 5 months after RT.
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f2-mco-0-0-1477
Representative cases are shown in Figs. 2 and 3. He previously underwent CCRT for right maxillary carcinoma in our hospital (Fig. 2). Prophylactic tooth extraction was performed before initiating CCRT in our department (Fig. 2). Retrospective evaluation of the post-treatment follow-up PET CT revealed sequential uptake of FDG (Fig. 2). The extent of FDG uptake was slight (same signal as non-specific uptake) on PET CT at 2 years 2 months after CCRT completion (Fig. 2). On PET CT at 3 years 1 month after CCRT, we found localized accumulation of FDG around the left mandibular canine (Fig. 2). Hence, the type of FDG accumulation was extensive (PET classification) (Fig. 2). At the second visit, only a small fistula with pus discharge was found in the left mandibular molar region (Fig. 2). However, the panoramic radiographic image obtained at the second visit showed bone resorption in the left mandibular molar region (Fig. 2).
Representative case of increased FDG accumulation: Spot type changing to localized type. (A) Pre-treatment FDG-PET CT shows a left oropharyngeal carcinoma. (B and C) Planning CT images. Note the slight uptake of FDG in the axial view (D) 3 years 7 months after RT and the spot type of FDG accumulation (arrowhead) in the axial view (E) 4 years 8 months after RT. (F) Localized type of FDG accumulation (arrowhead) in the axial view 5 years 8 months after RT. (G) Panoramic radiography shows no obvious bone resorption (arrowhead) in the anterior edge of the left mandibular ramus 5 years 10 months after RT. (H) Bone exposure with a mucosal defect (arrowhead) in the left retromolar region 5 years 10 months after RT. (I) Removed sequestrum after repeated conservative treatment. (J) Epithelialization (arrowhead) was achieved after sequestrectomy. (K) Disappearance of FDG accumulation after healing of mandibular osteoradionecrosis.
mco-08-01-0061-g02.jpg
PMC5769210_02_mco-08-01-0061-g02.jpg
f3-mco-0-0-1477
He previously underwent CCRT for left oropharyngeal carcinoma in our hospital (Fig. 3) and an oral examination before CCRT initiation in our department. Retrospective evaluation of the post-treatment follow-up PET CT revealed sequential FDG uptake (Fig. 3). The FDG accumulation was not found on PET CT at 3 years 7 months after CCRT completion (Fig. 3). However, on PET CT at 4 years 8 months after CCRT, spot accumulation of FDG at the anterior edge of the left mandibular ramus was found (Fig. 3). On PET CT at 5 years 8 months after CCRT, an area of bone resorption was found along the left ramus, changing the type of PET classification to localized accumulation of FDG (Fig. 3). Although the panoramic radiographic image at the second visit did not show obvious bone resorption at the left mandibular ramus (Fig. 3), a fistula with exposure of necrotic bone was found in the left retromolar region (Fig. 3). He was treated conservatively with repeated local irrigation and sequestrectomy under local anesthesia (Fig. 3), which resulted in epithelialization of the area with necrotic bone exposure (Fig. 3). Recent PET CT showed no FDG accumulation in the mandible (Fig. 3).
PMC5769210_02
Representative case of increased FDG accumulation: Spot type changing to localized type. (A) Pre-treatment FDG-PET CT shows a left oropharyngeal carcinoma. (B and C) Planning CT images. Note the slight uptake of FDG in the axial view (D) 3 years 7 months after RT and the spot type of FDG accumulation (arrowhead) in the axial view (E) 4 years 8 months after RT. (F) Localized type of FDG accumulation (arrowhead) in the axial view 5 years 8 months after RT. (G) Panoramic radiography shows no obvious bone resorption (arrowhead) in the anterior edge of the left mandibular ramus 5 years 10 months after RT. (H) Bone exposure with a mucosal defect (arrowhead) in the left retromolar region 5 years 10 months after RT. (I) Removed sequestrum after repeated conservative treatment. (J) Epithelialization (arrowhead) was achieved after sequestrectomy. (K) Disappearance of FDG accumulation after healing of mandibular osteoradionecrosis.
mco-08-01-0061-g02.jpg
PMC5769210_02_mco-08-01-0061-g02.jpg
f3-mco-0-0-1477
He previously underwent CCRT for left oropharyngeal carcinoma in our hospital (Fig. 3) and an oral examination before CCRT initiation in our department. Retrospective evaluation of the post-treatment follow-up PET CT revealed sequential FDG uptake (Fig. 3). The FDG accumulation was not found on PET CT at 3 years 7 months after CCRT completion (Fig. 3). However, on PET CT at 4 years 8 months after CCRT, spot accumulation of FDG at the anterior edge of the left mandibular ramus was found (Fig. 3). On PET CT at 5 years 8 months after CCRT, an area of bone resorption was found along the left ramus, changing the type of PET classification to localized accumulation of FDG (Fig. 3). Although the panoramic radiographic image at the second visit did not show obvious bone resorption at the left mandibular ramus (Fig. 3), a fistula with exposure of necrotic bone was found in the left retromolar region (Fig. 3). He was treated conservatively with repeated local irrigation and sequestrectomy under local anesthesia (Fig. 3), which resulted in epithelialization of the area with necrotic bone exposure (Fig. 3). Recent PET CT showed no FDG accumulation in the mandible (Fig. 3).