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Type:
Educational Exhibit
Keywords:
Head and neck, Oncology, Ear / Nose / Throat, MR, PET-CT, Radiation therapy / Oncology, Chemotherapy, Treatment effects, Cancer, Neoplasia, Radiation oncology in Developing Nations
Authors:
A. S. KAWTHALKAR1, A. Mahajan2, S. Arya2; 1MUMBAI, MA/IN, 2MUMBAI, MAHARASHTRA/IN
DOI:
10.1594/ecr2016/C-0674
Findings and procedure details
Material and Methods
In patients treated for nasopharyngeal carcinoma with precision external beam radiotherapy techniques alone or with precision external beam radiotherapy and concurrent chemotherapy,
CE-MRI and FDG PET-CT were first performed at least 10 -12 weeks post-therapy.
Subsequent imaging was performed every 6 months.
CE-MRI was performed on 1.5 Tesla GE or Philips scanners and PETCTs were performed on a GE Discovery scanner.
Image Analysis
Features assessed were
1.Recurrent mass at the primary site and spread to the oro and hypopharynx.
2.
Lateral extension to parapharyngeal and masticator spaces
3.
Skull base and prevertebral muscle involvement
4.
Perineural spread
5.
Intracranial extension and dural involvement
6.
Metastatic lymphadenopathy and
7.
Distant metastases.
Results
- For detection of recurrence at the primary site (Figure 1),
lateral extension to the parapharyngeal and masticator spaces and skull base erosion MRI and FDG PET-CT were found to be equally efficacious.
However in some cases marrow invasion seen on MRI was missed on both the morphologic and physiologic component of FDG-PETCT (Figure 2 and Figure 3).
- Intracranial extension and perineural spread (Figure 4 and Figure 5) were found to be better demonstrated on MRI.
- Secondary effects of tumor spread like sequelae of cranial nerve palsy such as unilateral hemi-atrophy of intrinsic tongue muscles were better detected by MR imaging.
- MR also had the advantage of higher detection rate of adverse effects of radiation therapy such as temporal lobe necrosis.
- However FDG PET-CT showed a higher efficacy than MRI for detecting metastatic adenopathy (Figure 6) and distant organ metastases (Figure 7).
Some lymph nodes which appeared indeterminate on MR were unequivocally characterized as either metastatic or reactive based on their specific uptake values (SUV) on FDG PET-CT.
- In few cases in which MR findings were equivocal for disease recurrence vs post-treatment changes,
FDG PET-CT proved to be a problem solving tool and clearly demonstrated either active disease or post-radiotherapy fibrosis based on the uptake of FDG (Figure 8).