1. HEAD AND NECK: HN19

2. POST TREATMENT FOLLOW-UP OF NASOPHARYNGEAL CANCER IN MRI L. EL ASSASSE, S. BOUTACHALI, F. AMRAOUI, R. LATIB, I. CHAMI, N. BOUJIDA, L. JROUNDI Radiology Service. National Institute of Oncology. Rabat. Morocco

3. INTRODUCTION  Nasopharyngeal cancer is frequent worldwide. Morocco is part of the zone of intermediate frequency.  Imaging plays a role both in diagnosis, staging, and follow-up post treatment.  MRI represents the main means of monitoring imaging.

4. MATERIALS AND METHODS:  These are cases collected in the radiology service of the national institute of oncology for patients treated for nasopharyngeal cancer and followed by MRI.

5. RESULTS AND DISCUSSION  Value of MRI:  Evaluate treatment response.  Detect early recurrence.  Look for complications of treatment.  Guide biopsies.

6.  MRI PROTOCOL:  1 time / year for 5 years, then every 5 years.  Thickness of slices 3-5 mm.  T1 T2 sequences, Gadolinium with FATSAT.  Functional sequences: diffusion and perfusion. RESULTS AND DISCUSSION

7.  NORMAL POST THERAPEUTIC ASPECTS:  Almost normal cavum.  Atrophy with irregularities of the mucosa.  Mucosal thickening.  Asymmetric cavum with loss of substance in case of large initial tumor.  Bone remodeling especially the sphenoid, sometimes cervical spine. RESULTS AND DISCUSSION

8. Fig. 1: Axial T1 SE cavum MRI after gadolinium injection: control of a nasopharyngeal carcinoma treated by radiotherapy. Loss of substance without enhanced residual tumor.Reference 1

9.  COMPLICATIONS OF RADIOTHERAPY:  Neurological complications: late-onset  Cerebral radionecrosis: especially at the lower part of the temporal lobes, T1 hypointense lesion and T2 hyperintense with inconstant contrast enhancement and parenchymal atrophy in the chronic phase (spectroscopy is used to differentiate between radionecrosis and brain metastasis). RESULTS AND DISCUSSION

10. Fig 2: Coronal T2 SE MRI : Radionecrosis in left temporal lobe (a)

11.  Radiation myelopathy:  Radiation myelopathy: spinal cord enlargement with abnormal signal of irradiated tissue, and later spinal cord atrophy.  Vascular complications: rare  Radiation stenosis: circumferential regular noncalcified. vascular thickening.  Thrombosis and pseudoaneurysm: exceptional. RESULTS AND DISCUSSION

12. Fig 3: T2 sagittal SE spinal MRI: Spinal cord enlargement with intramedullary high-signal T2. Radiation myelopathy. Reference 2

13.  Radiation-induced tumors: exceptional, occurring 5-10 years after treatment. Especially sarcomas.  Choanal stenosis post radiation. RESULTS AND DISCUSSION

14.  TUMOR RECURRENCE:  Parietal thickening with enhanced after injection.  Diffusion: decreased ADC and high-signal on b1000.  Perfusion: a decreased perfusion  low probability of recurrence. RESULTS AND DISCUSSION

15. Fig 4: Coronal SE T1 MRI after Gadolinium injection: Recurrent nasopharyngeal cancer in the left cavernous sinus

16.  MRI is currently the first-line examination to detect local and intracranial recurrence after treatment of nasopharyngeal cancer. CONCLUSION

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