DOI: 10.1148/rg.254045136
Combined PET-CT in the Head and Neck
Part 2. Diagnostic Uses and Pitfalls of Oncologic Imaging1
Melanie B. Fukui, MD,
Todd M. Blodgett, MD,
Carl H. Snyderman, MD,
Jonas J. Johnson, MD,
Eugene N. Myers, MD,
Dave W. Townsend, PhD and
Carolyn C. Meltzer, MD
1 From the Department of Radiology, Allegheny General Hospital, 320 E North Ave, Pittsburgh, PA 15212 (M.B.F.) and the Departments of Radiology (T.M.B., D.W.T., C.C.M.), Otolaryngology (C.H.S., J.J.J., E.N.M.), Psychiatry (C.C.M.), and Neurology (C.C.M.), University of Pittsburgh, Pa. Presented as an education exhibit at the 2001 RSNA Annual Meeting. Received June 28, 2004; revision requested July 22 and received March 11, 2005; accepted March 14. T.M.B. is a consultant for Petnet Pharmaceuticals; D.W.T. is a consultant for CPS Innovations; all remaining authors have no financial relationships to disclose.
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Figure 1a. Recurrent tumor. (a) Fused PET-CT scan shows a squamous cell carcinoma of the tonsil (arrow). The patient underwent partial mandibulectomy. (b) CT scan obtained 4 months later fails to demonstrate recurrent disease at the posterior flap margin (arrow), as did physical examination. (c) Follow-up PET-CT scan shows a small (<1-cm) focus of increased FDG uptake (standardized uptake value [SUV] = 2.5) (arrow). Subsequent surgery helped confirm tumor recurrence at the superficial posterior aspect of the muscle flap.
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Figure 1b. Recurrent tumor. (a) Fused PET-CT scan shows a squamous cell carcinoma of the tonsil (arrow). The patient underwent partial mandibulectomy. (b) CT scan obtained 4 months later fails to demonstrate recurrent disease at the posterior flap margin (arrow), as did physical examination. (c) Follow-up PET-CT scan shows a small (<1-cm) focus of increased FDG uptake (standardized uptake value [SUV] = 2.5) (arrow). Subsequent surgery helped confirm tumor recurrence at the superficial posterior aspect of the muscle flap.
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Figure 1c. Recurrent tumor. (a) Fused PET-CT scan shows a squamous cell carcinoma of the tonsil (arrow). The patient underwent partial mandibulectomy. (b) CT scan obtained 4 months later fails to demonstrate recurrent disease at the posterior flap margin (arrow), as did physical examination. (c) Follow-up PET-CT scan shows a small (<1-cm) focus of increased FDG uptake (standardized uptake value [SUV] = 2.5) (arrow). Subsequent surgery helped confirm tumor recurrence at the superficial posterior aspect of the muscle flap.
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Figure 2a. Recurrent tumor in a 61-year-old patient with a history of squamous cell carcinoma of the right side of the tongue base. The patient had undergone extensive resection of the primary tumor. CT and PET-CT were performed to investigate the cause of recurrent pain. (a) CT scan fails to demonstrate recurrent neoplasm (arrow). (b) PET-CT scan shows focal intense FDG uptake in the supraglottic larynx (arrow), a finding that proved to be recurrent neoplasm.
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Figure 2b. Recurrent tumor in a 61-year-old patient with a history of squamous cell carcinoma of the right side of the tongue base. The patient had undergone extensive resection of the primary tumor. CT and PET-CT were performed to investigate the cause of recurrent pain. (a) CT scan fails to demonstrate recurrent neoplasm (arrow). (b) PET-CT scan shows focal intense FDG uptake in the supraglottic larynx (arrow), a finding that proved to be recurrent neoplasm.
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Figure 3a. Unsuspected residual tumor in a 72-year-old patient with a history of nasal adenocarcinoma that had invaded the orbit. The patient had undergone left maxillectomy, orbital exenteration, and left ethmoidectomy with flap reconstruction 6 weeks earlier. (a) CT scan demonstrates soft tissue along the posterior flap margin (arrow), a finding that was suspicious for neoplasm. (b) PET-CT scan demonstrates intense FDG uptake localized to the lateral flap border (arrow), a finding that proved to be residual neoplasm at histologic analysis. (c) Follow-up PET-CT scan obtained after resection of the residual neoplasm shows no disease (arrow).
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Figure 3b. Unsuspected residual tumor in a 72-year-old patient with a history of nasal adenocarcinoma that had invaded the orbit. The patient had undergone left maxillectomy, orbital exenteration, and left ethmoidectomy with flap reconstruction 6 weeks earlier. (a) CT scan demonstrates soft tissue along the posterior flap margin (arrow), a finding that was suspicious for neoplasm. (b) PET-CT scan demonstrates intense FDG uptake localized to the lateral flap border (arrow), a finding that proved to be residual neoplasm at histologic analysis. (c) Follow-up PET-CT scan obtained after resection of the residual neoplasm shows no disease (arrow).
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Figure 3c. Unsuspected residual tumor in a 72-year-old patient with a history of nasal adenocarcinoma that had invaded the orbit. The patient had undergone left maxillectomy, orbital exenteration, and left ethmoidectomy with flap reconstruction 6 weeks earlier. (a) CT scan demonstrates soft tissue along the posterior flap margin (arrow), a finding that was suspicious for neoplasm. (b) PET-CT scan demonstrates intense FDG uptake localized to the lateral flap border (arrow), a finding that proved to be residual neoplasm at histologic analysis. (c) Follow-up PET-CT scan obtained after resection of the residual neoplasm shows no disease (arrow).
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Figure 4a. Recurrent papillary carcinoma of the thyroid gland. The patient had a rising thyroglobulin level but a negative 131I scan. (a) CT scan shows a paratracheal nodule (arrow) that had not been discovered at two previous surgeries, likely because of distorted anatomy and scar from the original thyroidectomy. (b) PET-CT scan demonstrates increased FDG uptake in the thyroidectomy bed (arrow) and provides the additional data needed to justify and guide a third surgical procedure, which helped confirm recurrent neoplasm.
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Figure 4b. Recurrent papillary carcinoma of the thyroid gland. The patient had a rising thyroglobulin level but a negative 131I scan. (a) CT scan shows a paratracheal nodule (arrow) that had not been discovered at two previous surgeries, likely because of distorted anatomy and scar from the original thyroidectomy. (b) PET-CT scan demonstrates increased FDG uptake in the thyroidectomy bed (arrow) and provides the additional data needed to justify and guide a third surgical procedure, which helped confirm recurrent neoplasm.
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Figure 5a. Recurrent thyroid papillary carcinoma in a 28-year-old patient with a rising thyroglobulin level but a negative 131I scan. CT (a) and fused PET-CT (b) scans show minimal asymmetric FDG uptake in the right side of the neck (arrow), a finding that represents a normal-sized level II lymph node. Recurrent papillary carcinoma was confirmed at histologic analysis.
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Figure 5b. Recurrent thyroid papillary carcinoma in a 28-year-old patient with a rising thyroglobulin level but a negative 131I scan. CT (a) and fused PET-CT (b) scans show minimal asymmetric FDG uptake in the right side of the neck (arrow), a finding that represents a normal-sized level II lymph node. Recurrent papillary carcinoma was confirmed at histologic analysis.
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Figure 6a. Recurrent skull base tumor in a 79-year-old man with a history of inverting papilloma complicated by sphenoid sinus carcinoma, which had previously been resected. Follow-up CT showed soft tissue in the right sphenoid sinus and an adjacent discontinuity in the lateral sphenoid sinus wall that was interpreted as either a surgical defect or neoplastic erosion. (a, b) Initial PET (a) and PET-CT (b) scans show focal FDG uptake localized to the soft-tissue lesion (arrow). The patient refused to undergo biopsy. (c, d) PET (c) and PET-CT (d) scans obtained 3 months later show increased FDG uptake in the lesion (arrow), a finding that supported the diagnosis of recurrent squamous cell carcinoma.
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Figure 6b. Recurrent skull base tumor in a 79-year-old man with a history of inverting papilloma complicated by sphenoid sinus carcinoma, which had previously been resected. Follow-up CT showed soft tissue in the right sphenoid sinus and an adjacent discontinuity in the lateral sphenoid sinus wall that was interpreted as either a surgical defect or neoplastic erosion. (a, b) Initial PET (a) and PET-CT (b) scans show focal FDG uptake localized to the soft-tissue lesion (arrow). The patient refused to undergo biopsy. (c, d) PET (c) and PET-CT (d) scans obtained 3 months later show increased FDG uptake in the lesion (arrow), a finding that supported the diagnosis of recurrent squamous cell carcinoma.
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Figure 6c. Recurrent skull base tumor in a 79-year-old man with a history of inverting papilloma complicated by sphenoid sinus carcinoma, which had previously been resected. Follow-up CT showed soft tissue in the right sphenoid sinus and an adjacent discontinuity in the lateral sphenoid sinus wall that was interpreted as either a surgical defect or neoplastic erosion. (a, b) Initial PET (a) and PET-CT (b) scans show focal FDG uptake localized to the soft-tissue lesion (arrow). The patient refused to undergo biopsy. (c, d) PET (c) and PET-CT (d) scans obtained 3 months later show increased FDG uptake in the lesion (arrow), a finding that supported the diagnosis of recurrent squamous cell carcinoma.
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Figure 6d. Recurrent skull base tumor in a 79-year-old man with a history of inverting papilloma complicated by sphenoid sinus carcinoma, which had previously been resected. Follow-up CT showed soft tissue in the right sphenoid sinus and an adjacent discontinuity in the lateral sphenoid sinus wall that was interpreted as either a surgical defect or neoplastic erosion. (a, b) Initial PET (a) and PET-CT (b) scans show focal FDG uptake localized to the soft-tissue lesion (arrow). The patient refused to undergo biopsy. (c, d) PET (c) and PET-CT (d) scans obtained 3 months later show increased FDG uptake in the lesion (arrow), a finding that supported the diagnosis of recurrent squamous cell carcinoma.
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Figure 7a. Squamous cell carcinoma in a patient with a known right-sided level II lymph node. Primary site of neoplasm was unknown. Neoplasm was not identified in five tissue samples obtained at direct laryngoscopy and directed biopsies of the tongue base, tonsils, and nasopharynx. PET (a) and PET-CT (b) scans show an area of intense FDG uptake (SUV = 8) in the right tonsil (arrow). The next day, the patient again underwent direct laryngoscopy and multiple biopsies of the right side of the tongue base; analysis of six additional samples showed squamous cell carcinoma.
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Figure 7b. Squamous cell carcinoma in a patient with a known right-sided level II lymph node. Primary site of neoplasm was unknown. Neoplasm was not identified in five tissue samples obtained at direct laryngoscopy and directed biopsies of the tongue base, tonsils, and nasopharynx. PET (a) and PET-CT (b) scans show an area of intense FDG uptake (SUV = 8) in the right tonsil (arrow). The next day, the patient again underwent direct laryngoscopy and multiple biopsies of the right side of the tongue base; analysis of six additional samples showed squamous cell carcinoma.
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Figure 8a. Occult carcinoma. (a) PET-CT scan shows intense FDG uptake in a right-sided level II lymph node (arrow) that proved to be squamous cell carcinoma at pathologic analysis. FDG uptake in the tongue base was symmetric. Direct la-ryngoscopy and directed biopsies failed to reveal the primary site of neoplasm. (b) PET-CT scan obtained at the level of the tonsils also shows symmetric FDG uptake (arrow). Because PET-CT also failed to demonstrate the primary site of neoplasm, bilateral tonsillectomies were performed. Histologic examination showed hyperplasia in the left tonsil and squamous cell carcinoma in the right tonsil.
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Figure 8b. Occult carcinoma. (a) PET-CT scan shows intense FDG uptake in a right-sided level II lymph node (arrow) that proved to be squamous cell carcinoma at pathologic analysis. FDG uptake in the tongue base was symmetric. Direct la-ryngoscopy and directed biopsies failed to reveal the primary site of neoplasm. (b) PET-CT scan obtained at the level of the tonsils also shows symmetric FDG uptake (arrow). Because PET-CT also failed to demonstrate the primary site of neoplasm, bilateral tonsillectomies were performed. Histologic examination showed hyperplasia in the left tonsil and squamous cell carcinoma in the right tonsil.
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Figure 9a. Lymph node metastases in a 23-year-old patient with squamous cell carcinoma of the left ethmoid sinus. The patient had undergone two previous surgeries. (a–c) CT (a), PET (b), and PET-CT (c) scans obtained 10 months after presentation show local recurrence in the naso-pharynx (arrow). (d–i) CT scans (d, f, g, i; f and i are magnified views) and PET scans (e, h) show bilateral focal FDG uptake in small (<1-cm) cervical lymph nodes (arrow). These findings prompted resection of the local recurrence as well as bilateral modified neck dissections, the results of which confirmed recurrent neoplasm in both lymph nodes.
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Figure 9b. Lymph node metastases in a 23-year-old patient with squamous cell carcinoma of the left ethmoid sinus. The patient had undergone two previous surgeries. (a–c) CT (a), PET (b), and PET-CT (c) scans obtained 10 months after presentation show local recurrence in the naso-pharynx (arrow). (d–i) CT scans (d, f, g, i; f and i are magnified views) and PET scans (e, h) show bilateral focal FDG uptake in small (<1-cm) cervical lymph nodes (arrow). These findings prompted resection of the local recurrence as well as bilateral modified neck dissections, the results of which confirmed recurrent neoplasm in both lymph nodes.
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Figure 9c. Lymph node metastases in a 23-year-old patient with squamous cell carcinoma of the left ethmoid sinus. The patient had undergone two previous surgeries. (a–c) CT (a), PET (b), and PET-CT (c) scans obtained 10 months after presentation show local recurrence in the naso-pharynx (arrow). (d–i) CT scans (d, f, g, i; f and i are magnified views) and PET scans (e, h) show bilateral focal FDG uptake in small (<1-cm) cervical lymph nodes (arrow). These findings prompted resection of the local recurrence as well as bilateral modified neck dissections, the results of which confirmed recurrent neoplasm in both lymph nodes.
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Figure 9d. Lymph node metastases in a 23-year-old patient with squamous cell carcinoma of the left ethmoid sinus. The patient had undergone two previous surgeries. (a–c) CT (a), PET (b), and PET-CT (c) scans obtained 10 months after presentation show local recurrence in the naso-pharynx (arrow). (d–i) CT scans (d, f, g, i; f and i are magnified views) and PET scans (e, h) show bilateral focal FDG uptake in small (<1-cm) cervical lymph nodes (arrow). These findings prompted resection of the local recurrence as well as bilateral modified neck dissections, the results of which confirmed recurrent neoplasm in both lymph nodes.
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Figure 9e. Lymph node metastases in a 23-year-old patient with squamous cell carcinoma of the left ethmoid sinus. The patient had undergone two previous surgeries. (a–c) CT (a), PET (b), and PET-CT (c) scans obtained 10 months after presentation show local recurrence in the naso-pharynx (arrow). (d–i) CT scans (d, f, g, i; f and i are magnified views) and PET scans (e, h) show bilateral focal FDG uptake in small (<1-cm) cervical lymph nodes (arrow). These findings prompted resection of the local recurrence as well as bilateral modified neck dissections, the results of which confirmed recurrent neoplasm in both lymph nodes.
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Figure 9f. Lymph node metastases in a 23-year-old patient with squamous cell carcinoma of the left ethmoid sinus. The patient had undergone two previous surgeries. (a–c) CT (a), PET (b), and PET-CT (c) scans obtained 10 months after presentation show local recurrence in the naso-pharynx (arrow). (d–i) CT scans (d, f, g, i; f and i are magnified views) and PET scans (e, h) show bilateral focal FDG uptake in small (<1-cm) cervical lymph nodes (arrow). These findings prompted resection of the local recurrence as well as bilateral modified neck dissections, the results of which confirmed recurrent neoplasm in both lymph nodes.
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Figure 9g. Lymph node metastases in a 23-year-old patient with squamous cell carcinoma of the left ethmoid sinus. The patient had undergone two previous surgeries. (a–c) CT (a), PET (b), and PET-CT (c) scans obtained 10 months after presentation show local recurrence in the naso-pharynx (arrow). (d–i) CT scans (d, f, g, i; f and i are magnified views) and PET scans (e, h) show bilateral focal FDG uptake in small (<1-cm) cervical lymph nodes (arrow). These findings prompted resection of the local recurrence as well as bilateral modified neck dissections, the results of which confirmed recurrent neoplasm in both lymph nodes.
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Figure 9h. Lymph node metastases in a 23-year-old patient with squamous cell carcinoma of the left ethmoid sinus. The patient had undergone two previous surgeries. (a–c) CT (a), PET (b), and PET-CT (c) scans obtained 10 months after presentation show local recurrence in the naso-pharynx (arrow). (d–i) CT scans (d, f, g, i; f and i are magnified views) and PET scans (e, h) show bilateral focal FDG uptake in small (<1-cm) cervical lymph nodes (arrow). These findings prompted resection of the local recurrence as well as bilateral modified neck dissections, the results of which confirmed recurrent neoplasm in both lymph nodes.
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Figure 9i. Lymph node metastases in a 23-year-old patient with squamous cell carcinoma of the left ethmoid sinus. The patient had undergone two previous surgeries. (a–c) CT (a), PET (b), and PET-CT (c) scans obtained 10 months after presentation show local recurrence in the naso-pharynx (arrow). (d–i) CT scans (d, f, g, i; f and i are magnified views) and PET scans (e, h) show bilateral focal FDG uptake in small (<1-cm) cervical lymph nodes (arrow). These findings prompted resection of the local recurrence as well as bilateral modified neck dissections, the results of which confirmed recurrent neoplasm in both lymph nodes.
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Figure 10a. Tumor recurrence in a 50-year-old patient with a history of squamous cell carcinoma of the tongue base. The patient had undergone chemotherapy and radiation therapy in Germany 2 years earlier. MR imaging performed there demonstrated extensive tumor involvement of the tongue base and larynx. PET-CT scans show tumor recurrence in the tongue base (arrow in a) but sparing of the supraglottic larynx (arrow in b), involvement of which had been suspected at CT. The PET-CT findings allowed the patient to undergo more conservative surgery than would have been indicated by the CT data alone.
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Figure 10b. Tumor recurrence in a 50-year-old patient with a history of squamous cell carcinoma of the tongue base. The patient had undergone chemotherapy and radiation therapy in Germany 2 years earlier. MR imaging performed there demonstrated extensive tumor involvement of the tongue base and larynx. PET-CT scans show tumor recurrence in the tongue base (arrow in a) but sparing of the supraglottic larynx (arrow in b), involvement of which had been suspected at CT. The PET-CT findings allowed the patient to undergo more conservative surgery than would have been indicated by the CT data alone.
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Figure 11a. Distant metastasis in a 61-year-old patient with recently diagnosed squamous cell carcinoma of the right side of the oropharynx. The patient had undergone CT, which showed no evidence of distant metastasis. (a) CT scan shows no lesion in the sternum (arrow). (b) PET-CT scan shows a small focus of FDG uptake localized to the sternum (arrow), a finding that is consistent with metastasis. PET-CT also showed intense FDG uptake at the primary site.
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Figure 11b. Distant metastasis in a 61-year-old patient with recently diagnosed squamous cell carcinoma of the right side of the oropharynx. The patient had undergone CT, which showed no evidence of distant metastasis. (a) CT scan shows no lesion in the sternum (arrow). (b) PET-CT scan shows a small focus of FDG uptake localized to the sternum (arrow), a finding that is consistent with metastasis. PET-CT also showed intense FDG uptake at the primary site.
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Figure 12a. Second primary lung tumor in a patient who presented with throat pain. The patient had undergone chemotherapy and radiation therapy for squamous cell carcinoma of the oropharynx 6 years earlier. (a) PET-CT scan demonstrates recurrent neoplasm in the left retromolar trigone (arrow). (b) CT scan shows stranding in the lung apices (arrow), a finding that was interpreted as radiation-induced change. (c) PET-CT scan demonstrates intense FDG uptake in the right lung apex (arrow), a finding that proved to be a second primary adenocarcinoma.
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Figure 12b. Second primary lung tumor in a patient who presented with throat pain. The patient had undergone chemotherapy and radiation therapy for squamous cell carcinoma of the oropharynx 6 years earlier. (a) PET-CT scan demonstrates recurrent neoplasm in the left retromolar trigone (arrow). (b) CT scan shows stranding in the lung apices (arrow), a finding that was interpreted as radiation-induced change. (c) PET-CT scan demonstrates intense FDG uptake in the right lung apex (arrow), a finding that proved to be a second primary adenocarcinoma.
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Figure 12c. Second primary lung tumor in a patient who presented with throat pain. The patient had undergone chemotherapy and radiation therapy for squamous cell carcinoma of the oropharynx 6 years earlier. (a) PET-CT scan demonstrates recurrent neoplasm in the left retromolar trigone (arrow). (b) CT scan shows stranding in the lung apices (arrow), a finding that was interpreted as radiation-induced change. (c) PET-CT scan demonstrates intense FDG uptake in the right lung apex (arrow), a finding that proved to be a second primary adenocarcinoma.
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Figure 13a. Recurrent neoplasm in a 67-year-old patient with progressive dyspnea in whom squamous cell carcinoma of the tongue base had been diagnosed. (a) Initial PET-CT scan shows a large focus of intense FDG uptake in the tongue base (arrow) and uptake in bilateral level II lymph nodes. The patient subsequently underwent chemotherapy and radiation therapy. (b) PET-CT scan shows a decrease in FDG uptake in the tongue base (arrow) and resolution of the nodal uptake. (c) PET-CT scan reveals new FDG uptake in the vocal cords and sclerosis of the left side of the thyroid cartilage (arrow). These findings were interpreted as representing inflammation. Direct laryngoscopy was performed and showed radiation-induced change in the true vocal cords. (d) Follow-up PET-CT scan shows increased FDG uptake in the thyroid cartilage (arrow), a finding that represents recurrent neoplasm in proximity to the vocal cords.
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Figure 13b. Recurrent neoplasm in a 67-year-old patient with progressive dyspnea in whom squamous cell carcinoma of the tongue base had been diagnosed. (a) Initial PET-CT scan shows a large focus of intense FDG uptake in the tongue base (arrow) and uptake in bilateral level II lymph nodes. The patient subsequently underwent chemotherapy and radiation therapy. (b) PET-CT scan shows a decrease in FDG uptake in the tongue base (arrow) and resolution of the nodal uptake. (c) PET-CT scan reveals new FDG uptake in the vocal cords and sclerosis of the left side of the thyroid cartilage (arrow). These findings were interpreted as representing inflammation. Direct laryngoscopy was performed and showed radiation-induced change in the true vocal cords. (d) Follow-up PET-CT scan shows increased FDG uptake in the thyroid cartilage (arrow), a finding that represents recurrent neoplasm in proximity to the vocal cords.
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Figure 13c. Recurrent neoplasm in a 67-year-old patient with progressive dyspnea in whom squamous cell carcinoma of the tongue base had been diagnosed. (a) Initial PET-CT scan shows a large focus of intense FDG uptake in the tongue base (arrow) and uptake in bilateral level II lymph nodes. The patient subsequently underwent chemotherapy and radiation therapy. (b) PET-CT scan shows a decrease in FDG uptake in the tongue base (arrow) and resolution of the nodal uptake. (c) PET-CT scan reveals new FDG uptake in the vocal cords and sclerosis of the left side of the thyroid cartilage (arrow). These findings were interpreted as representing inflammation. Direct laryngoscopy was performed and showed radiation-induced change in the true vocal cords. (d) Follow-up PET-CT scan shows increased FDG uptake in the thyroid cartilage (arrow), a finding that represents recurrent neoplasm in proximity to the vocal cords.
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Figure 13d. Recurrent neoplasm in a 67-year-old patient with progressive dyspnea in whom squamous cell carcinoma of the tongue base had been diagnosed. (a) Initial PET-CT scan shows a large focus of intense FDG uptake in the tongue base (arrow) and uptake in bilateral level II lymph nodes. The patient subsequently underwent chemotherapy and radiation therapy. (b) PET-CT scan shows a decrease in FDG uptake in the tongue base (arrow) and resolution of the nodal uptake. (c) PET-CT scan reveals new FDG uptake in the vocal cords and sclerosis of the left side of the thyroid cartilage (arrow). These findings were interpreted as representing inflammation. Direct laryngoscopy was performed and showed radiation-induced change in the true vocal cords. (d) Follow-up PET-CT scan shows increased FDG uptake in the thyroid cartilage (arrow), a finding that represents recurrent neoplasm in proximity to the vocal cords.
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Figure 14a. Squamous cell carcinoma of the tongue in a 60-year-old patient who had undergone chemotherapy and radiation therapy 2 years earlier. (a, b) PET-CT scans show faint FDG uptake in the left side of the tongue base (primary site) and in a left-sided level II lymph node (long arrow), as well as intense physiologic uptake in the genioglossus muscle (short arrow). The patient subsequently underwent gene therapy. (c, d) PET-CT scans obtained 3 months later show disease progression, with increased FDG uptake in the left side of the tongue base and in the lymph node (arrow).
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Figure 14b. Squamous cell carcinoma of the tongue in a 60-year-old patient who had undergone chemotherapy and radiation therapy 2 years earlier. (a, b) PET-CT scans show faint FDG uptake in the left side of the tongue base (primary site) and in a left-sided level II lymph node (long arrow), as well as intense physiologic uptake in the genioglossus muscle (short arrow). The patient subsequently underwent gene therapy. (c, d) PET-CT scans obtained 3 months later show disease progression, with increased FDG uptake in the left side of the tongue base and in the lymph node (arrow).
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Figure 14c. Squamous cell carcinoma of the tongue in a 60-year-old patient who had undergone chemotherapy and radiation therapy 2 years earlier. (a, b) PET-CT scans show faint FDG uptake in the left side of the tongue base (primary site) and in a left-sided level II lymph node (long arrow), as well as intense physiologic uptake in the genioglossus muscle (short arrow). The patient subsequently underwent gene therapy. (c, d) PET-CT scans obtained 3 months later show disease progression, with increased FDG uptake in the left side of the tongue base and in the lymph node (arrow).
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Figure 14d. Squamous cell carcinoma of the tongue in a 60-year-old patient who had undergone chemotherapy and radiation therapy 2 years earlier. (a, b) PET-CT scans show faint FDG uptake in the left side of the tongue base (primary site) and in a left-sided level II lymph node (long arrow), as well as intense physiologic uptake in the genioglossus muscle (short arrow). The patient subsequently underwent gene therapy. (c, d) PET-CT scans obtained 3 months later show disease progression, with increased FDG uptake in the left side of the tongue base and in the lymph node (arrow).
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Figure 15a. Nasopharyngeal carcinoma in a 62-year-old patient. (a) Coronal PET scan shows intense FDG uptake (arrow) in proximity to the brain. (b) Axial fused PET-CT scan helps localize the FDG uptake to extensive neoplastic erosion of the sphenoid bone (arrow) rather than the brain.
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Figure 15b. Nasopharyngeal carcinoma in a 62-year-old patient. (a) Coronal PET scan shows intense FDG uptake (arrow) in proximity to the brain. (b) Axial fused PET-CT scan helps localize the FDG uptake to extensive neoplastic erosion of the sphenoid bone (arrow) rather than the brain.
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Figure 16a. Tonsillar uptake. PET (a) and PET-CT (b) scans demonstrate intense physiologic FDG uptake in the tonsils (arrow). Such uptake creates high background activity that makes it difficult to detect an unknown primary neoplasm.
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Figure 16b. Tonsillar uptake. PET (a) and PET-CT (b) scans demonstrate intense physiologic FDG uptake in the tonsils (arrow). Such uptake creates high background activity that makes it difficult to detect an unknown primary neoplasm.
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Figure 17a. Squamous cell carcinoma in a left-sided level II lymph node. PET and PET-CT were performed to search for the primary site. PET (a) and PET-CT (b) scans demonstrate slightly asymmetric FDG uptake in the left tonsil (arrow), a finding that was initially interpreted as physiologic uptake. Direct laryngoscopy and multiple biopsies of the tongue base and tonsils proved that the left tonsil was in fact the primary site.
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Figure 17b. Squamous cell carcinoma in a left-sided level II lymph node. PET and PET-CT were performed to search for the primary site. PET (a) and PET-CT (b) scans demonstrate slightly asymmetric FDG uptake in the left tonsil (arrow), a finding that was initially interpreted as physiologic uptake. Direct laryngoscopy and multiple biopsies of the tongue base and tonsils proved that the left tonsil was in fact the primary site.
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Figure 18a. Neoplastic spread in a patient who presented with severe dysesthesia in the distribution of the right fifth cranial nerve (maxillary and mandibular divisions). The patient had undergone resection of a right buccal squamous cell carcinoma 9 months earlier. (a) MR image (magnified view) shows an enhancing 5-mm lesion in the right fifth cranial nerve (mandibular division) in the foramen ovale (arrow). (b, c) PET (b) and PET-CT (c) scans show no FDG uptake in the fifth cranial nerve (mandibular division) (arrow), likely owing to the small lesion size. Perineural spread of neoplasm was confirmed at surgery.
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Figure 18b. Neoplastic spread in a patient who presented with severe dysesthesia in the distribution of the right fifth cranial nerve (maxillary and mandibular divisions). The patient had undergone resection of a right buccal squamous cell carcinoma 9 months earlier. (a) MR image (magnified view) shows an enhancing 5-mm lesion in the right fifth cranial nerve (mandibular division) in the foramen ovale (arrow). (b, c) PET (b) and PET-CT (c) scans show no FDG uptake in the fifth cranial nerve (mandibular division) (arrow), likely owing to the small lesion size. Perineural spread of neoplasm was confirmed at surgery.
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Figure 18c. Neoplastic spread in a patient who presented with severe dysesthesia in the distribution of the right fifth cranial nerve (maxillary and mandibular divisions). The patient had undergone resection of a right buccal squamous cell carcinoma 9 months earlier. (a) MR image (magnified view) shows an enhancing 5-mm lesion in the right fifth cranial nerve (mandibular division) in the foramen ovale (arrow). (b, c) PET (b) and PET-CT (c) scans show no FDG uptake in the fifth cranial nerve (mandibular division) (arrow), likely owing to the small lesion size. Perineural spread of neoplasm was confirmed at surgery.
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Figure 19a. Residual neoplasm in a 42-year-old patient who had undergone radical neck dissection, chemotherapy, and radiation therapy for squamous cell carcinoma of the right side of the tongue base and neck. (a) PET-CT scan obtained 31/2 weeks after radiation therapy shows linear, intensely increased FDG uptake in the right side of the neck (arrow), a finding that was interpreted as likely representing treatment-related changes. No definite abnormality had been seen at CT. (b, c) PET-CT scans obtained 4 months later show globular increased FDG uptake in the same location (arrow), as well as increased FDG uptake anteriorly (c). Thus, the initial FDG uptake represented residual neoplasm rather than treatment-related changes.
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Figure 19b. Residual neoplasm in a 42-year-old patient who had undergone radical neck dissection, chemotherapy, and radiation therapy for squamous cell carcinoma of the right side of the tongue base and neck. (a) PET-CT scan obtained 31/2 weeks after radiation therapy shows linear, intensely increased FDG uptake in the right side of the neck (arrow), a finding that was interpreted as likely representing treatment-related changes. No definite abnormality had been seen at CT. (b, c) PET-CT scans obtained 4 months later show globular increased FDG uptake in the same location (arrow), as well as increased FDG uptake anteriorly (c). Thus, the initial FDG uptake represented residual neoplasm rather than treatment-related changes.
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Figure 19c. Residual neoplasm in a 42-year-old patient who had undergone radical neck dissection, chemotherapy, and radiation therapy for squamous cell carcinoma of the right side of the tongue base and neck. (a) PET-CT scan obtained 31/2 weeks after radiation therapy shows linear, intensely increased FDG uptake in the right side of the neck (arrow), a finding that was interpreted as likely representing treatment-related changes. No definite abnormality had been seen at CT. (b, c) PET-CT scans obtained 4 months later show globular increased FDG uptake in the same location (arrow), as well as increased FDG uptake anteriorly (c). Thus, the initial FDG uptake represented residual neoplasm rather than treatment-related changes.
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Figure 20a. Dental abscess in a 56-year-old man with a history of squamous cell carcinoma of the left side of the tongue base. The patient had undergone resection and radiation therapy and presented with new left-sided facial pain. (a) CT scan shows no abnormality in the left maxilla (arrow). (b) PET-CT scan shows a focal area of intense FDG uptake in the left maxilla (arrow). Although neoplasm was suspected, the FDG uptake proved to represent a dental abscess.
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Figure 20b. Dental abscess in a 56-year-old man with a history of squamous cell carcinoma of the left side of the tongue base. The patient had undergone resection and radiation therapy and presented with new left-sided facial pain. (a) CT scan shows no abnormality in the left maxilla (arrow). (b) PET-CT scan shows a focal area of intense FDG uptake in the left maxilla (arrow). Although neoplasm was suspected, the FDG uptake proved to represent a dental abscess.
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Figure 21a. Lack of FDG uptake in a necrotic lymph node metastasis in a patient with squamous cell carcinoma of the right side of the tongue base. The patient underwent PET-CT for staging. (a) PET-CT scan shows a necrotic right-sided level II lymph node with focal uptake in the solid portion (arrow). However, no FDG uptake is noted in the more anterolateral necrotic component of the lymph node, a finding that represents a potential pitfall. (b) PET-CT scan shows unsuspected tumor involvement of a contralateral level II lymph node (arrow). This finding had not been detected at CT earlier, likely because the lymph node was inseparable from the left sternocleidomastoid muscle.
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Figure 21b. Lack of FDG uptake in a necrotic lymph node metastasis in a patient with squamous cell carcinoma of the right side of the tongue base. The patient underwent PET-CT for staging. (a) PET-CT scan shows a necrotic right-sided level II lymph node with focal uptake in the solid portion (arrow). However, no FDG uptake is noted in the more anterolateral necrotic component of the lymph node, a finding that represents a potential pitfall. (b) PET-CT scan shows unsuspected tumor involvement of a contralateral level II lymph node (arrow). This finding had not been detected at CT earlier, likely because the lymph node was inseparable from the left sternocleidomastoid muscle.
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Figure 22a. Spindle cell neoplasm in a 76-year-old patient. CT (a) and PET-CT (b) scans show sclerosis of the left maxillary sinus walls, in addition to a mass in the masticator space (arrow). The latter finding proved to be neuroendocrine carcinoma with bone invasion at histologic analysis. Spindle cell neoplasms, like some other neoplasms, may have low FDG avidity, thereby representing a potential pitfall.
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Figure 22b. Spindle cell neoplasm in a 76-year-old patient. CT (a) and PET-CT (b) scans show sclerosis of the left maxillary sinus walls, in addition to a mass in the masticator space (arrow). The latter finding proved to be neuroendocrine carcinoma with bone invasion at histologic analysis. Spindle cell neoplasms, like some other neoplasms, may have low FDG avidity, thereby representing a potential pitfall.
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Copyright © 2005 by the Radiological Society of North America.
