RESUMO
Objective To investigate the peri-nasopharyngeal invasion patterns of nasopharyngeal carcinoma (NPC) on MRI and its relationship with tumor staging. Methods One thousand five hundred and seventy-three patients with newly diagnosed NPC which were histo-pathologically proved were retrospectively studied. The MRI manifestations and invasion patterns of the NPCs were elevated according to the 2008 Tstaging system of NPC. Z test was used to analyze the rate of adjacent structures invasion in NPCs. Results The structures invaded by NPCs included pharyngobasilar fascia in 1299 cases (82. 58% ); parapharyngeal space, 1090 ( 69. 29% ); nasal cavities, 304 ( 19. 33% ); oropharynx, 49 ( 3. 12% ); carotid space,514(32. 68% ); medial pterygoid muscle, 661 (42. 02% ); lateral pterygoid muscle, 210( 13. 35% ); skull base bones, 943(59. 95% ); cranial nerves, 630(40. 05% ) and paranasal sinuses, 242 ( 15.38% ). The T-stage distribution was T1, 242 cases ( 15.38% ); T2, 288 ( 18. 31% ); T3, 410 (26. 06% ) and T4,633 (40. 24% ). Among the cases with nasal cavities invasion, 90. 46% (275/304)showed the involvement of the structures seen in T3 or T4 stage, which was found in all cases with oropharynx invasion. In addition,69. 14% (457/661) of cases with medial pterygoid muscle invasion and 92. 15% (223/242) of cases with paranasal sinuses invasion showed the involvement of structures seen in T4 stage. As for the invasion patterns of NPC, the lateral invasion of pharyngobasilar fascia was more frequent than upward invasion of skull base (Z = 14. 025, P ＜ 0. 01 ) and downward invasion of oropharynx ( Z = 45.032, P ＜ 0. 01 ), and the downward invasion of oropharynx was less frequent than upward invasion of skull base ( Z = 34. 301, P ＜ 0. 01 ) and forward invasion of nasal cavities ( Z = 14. 404, P ＜ 0. 01 ). Conclusion NPC has a predilection of lateral invasion rather than upward and downward invasion, and its upward and forward invasion are more common than downward invasion.
RESUMO
Objective To determine the diagnostic value of diffusion weighted imaging(DWI) for primary nasopharyngeal carcinoma(NPC) and metastatic lymph nodes,and to establish the diagnostic thresh-old of apparent diffusion coefficients(ADCs). Methods Conventional MR scans and DWI scans were con-tinuously performed in 56 patients with newly diagnosed NPC and 55 healthy volunteers. All patients re-ceived primary tumor biopsy and MR image-guided cervical lymph node fine-needle biopsy. ADC and eADC values of both primary lesions and lymph nodes were calculated and compared. Results According to the pathological diagnosis,all the 56 patients had non-keratinizing carcinoma and 51 had lymph node metastasis. In the control group,75 cervical lymph nodes were found. ADC values of both primary NPC and metastatic lymph nodes were significantly lower, while eADC values were higher than those of normal controls. Setting the ADC value threshold at 0.809 ×10-3 mm2/s, the sensitivity and specificity for primary NPC detection were 80.4% and 74.5%, respectively. The negative and positive predictive values were 79.2% and 77.6% ,respectively. The accuracy was 78.4%. Setting the ADC value threshold at 0. 708×10-3 mm2/s, the sensitivity and specificity in the detection of metastatic cervical lymph nodes were 43.1% and 93.3%, respectively. The negative and positive predictive values were 70.7% and 81.5% ,respectively. The accura-cy was 73.0%. Conclusions DWI might be a new diagnostic approach in the detection of primary NPC as well as metastatic lymph nodes.