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Objective:To analyze the effects of radiotherapy on the onset and progression of mastoiditis in patients with nasopharyngeal carcinoma (NPC) using magnetic resonance imaging (MRI) and to explore the risk factors for the onset of mastoiditis after radiotherapy.Methods:The onset and progression of mastoiditis of 204 NPC patients 3, 12, and 24 months after radiotherapy were analyzed based on MRI images. The multi-factor logistic regression analysis was applied to explore the risk factors of the onset of mastoiditis after radiotherapy. The cross-sectional area of the tensor veli palatini muscle was measured and the relationship between the atrophy degrees of the tensor veli palatini muscle and the onset of mastoiditis was analyzed.Results:The incidence of mastoiditis before radiotherapy was 20.6% (84/408, ears), and was 41.1% (168/408, ears), 22.3% (91/408, ears), and 19.6% (80/408, ears), respectively 3, 12, and 24 months after radiotherapy. The incidence of radiotherapy-induced mastoiditis was 35.8% (116/324, ears), 18.2% (59/324, ears), and 16.4% (53/324, ears), respectively 3, 12, and 24 months after radiotherapy. The remission rate of 63 patients (83 ears) who developed mastoiditis 3 months after radiotherapy was 63.9% (53/83, ears) and 75.9% (63/83, ears), respectively 12 and 24 months after radiotherapy. The remission rate of 54 patients (60 ears) who suffered mastoiditis before radiotherapy was 43.3% (26/60, ears), 65.0% (39/60, ears), and 73.3% (44/60, ears) 3, 12, and 24 months after radiotherapy. The multivariate analysis showed that the independent risk factors for radiotherapy-induced mastoiditis included age ≥50, clinical stages Ⅲ-Ⅳ, radiotherapy dose > 70 Gy, and tumors invading pharyngeal ostium of the eustachian tube. In addition, the atrophy degree of tensor veli palatini muscle 12 and 24 months after radiotherapy correlated with the onset of mastoiditis.Conclusions:The incidence of mastoiditis significantly increased 3 months after radiotherapy and significantly decreased 12 months after radiotherapy for NPC patients. The natural remission rate of radiotherapy-induced mastoiditis 12 months after radiotherapy was over 70%. The independent risk factors for radiotherapy-induced mastoiditis include age ≥50, clinical stages Ⅲ-Ⅳ, radiotherapy dose >70 Gy, and tumor invading pharyngeal ostium of the eustachian tube. The atrophy degree of the tensor veli palatini muscle 12 and 24 months after radiotherapy correlates with the onset of mastoiditis.
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Objective To evaluate the value of MRS in quantitative assessment of degeneration of lumbar discs.Methods Totally 82 patients with lumbago underwent lumbar MR scanning.All the discs were classified with Pfirrmann grades in the sequences of sagittal T2WI.The area under N-acetyl peak,under water peak and the ratio of N-acetyl/Water were measured by MRS.Correlation between MRS values and Pfirrmann grade,age were analyzed.Results In 82 patients,204 lumbar discs were measured by MRS.There were 89,73,39,3 discs in Pfirrmann Ⅱ,Ⅲ,Ⅳ,V respectively.The areas of N-acetyl,water peak and N-acetyl/Water ratio of nucleus region were positively correlated with Pfirrmann grading,respectively (rs =-0.460,-0.204,-0.526,all P＜0.05).There were 62,25,37,51,29 discs in patients aged ＜30,30-39,40-49,50-59,＞59 years respectively.The ares of N-acetyl peak,N-acetyl/Water ratio of nucleus region was negatively correlated with the age (rs=-0.247,-0.385,both P＜0.05).Conclusion MRS can be used for quantitative assessment of lumbar discs degeneration.
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BACKGROUND:Disc functional magnetic resonance imaging studies are mostly carried out under lying and a non-load state, and do not reflect the changes in morphology and function of the upright human body under disc load conditions. Therefore, we need to study characteristics of disc functional magnetic resonance imaging in the upright state. OBJECTIVE: To analyze the effect of axial load on apparent diffusion coefficient and T2 of intervertebral discs. METHODS:The study consisted of 17 patients with low back pain aged 34-65 years. Before and after axial load, T2 weighted MR imaging, T1 weighted MR imaging, diffusion tensor imaging, and T2-mapping imaging of the lumbar spine were performed. Load quality was 40%-50% body weight. At 10 minutes after axial load, another diffusion tensor imaging was performed. After 15-minute load, another T2-mapping sequence was scanned. Diffusion tensor imaging scan parameters: single echo-planar imaging, repetition time 2 500 ms, echo time 89 ms, six diffusion directions, b value of 400 s/mm2, sweep time 4:10 minutes. Raw data of diffusion tensor imaging were used to construct apparent diffusion coefficient map and b0 map. Apparent diffusion coefficient value of intervertebral discs was calculated before and after loading. T2 map was automaticaly constructed using T2-mapping sequence to measure apparent diffusion coefficient and T2 values in the whole intervertebral disc of nucleus pulposus, and the changes of them were analyzed under short-time axial load. RESULTS AND CONCLUSION:Pfirrmann grading results in 17 patients with 85 discs were obtained as folows: 0 in Grade I, 26 in Grade II, 19 in Grade III, 30 in Grade IV, and 10 in Grade V. Al 85 disc T2 relaxation time mapping and 84 disc apparent diffusion coefficient mapping were accepted. Under short-time axial load in 84 discs, apparent diffusion coefficient reduced in the whole disc (reduced 38×10-3 mm2/s,Z=2.567,P 0.05). These results suggest that changes in apparent diffusion coefficient and T2 values were different due to different Pfirrmann grades under short-time axial load. To evaluate magnetic resonance imaging function of intervertebral discs, we should choose different evaluation method according to different degeneration degrees.
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Objective To analysis the effect of axial loading to ADC value, FA of lumbar intervetebral discs. Methods Forty five patients with low back pain (age range, 25 to 54 years) were evaluated with MR T2WI, MR T1WI and diffusion tensor imaging (DTI) of the lumbar spine. Following axial loading with 40% to 50% body weight for 10 minutes, a repeat DTI was performed. DTI were obtained by using an echo-planar imaging ( EPI ) sequence, TE 89 ms, TR 2500 ms, b value of 400 s/mm2,6 noncollinear diffusion directions. Scan time was approximately 4 min 10 s. An isotropic ADC map, FA map and bo map were calculated from DTI sequence. The mean ADC value, FA prior to and following axialloading were analyzed with t test and Rank Sum test. Results Forty five patients with 225 discs were evaluated and 223 discs were included in the study except for 2 calcified discs. The Pfirrmann grading results were as following: 100 Grade Ⅱ , 48 Grade Ⅲ, 59 Grade Ⅳ, and 16 Grade Ⅴ. No significant difference existed in the mean ADC value before [ ( 1666 ± 252 ) × 10-3 mm2/s ] and after [ ( 1662 ± 253 ) ×10 -3 mm2/s ] axial loading ( Z = - 1.363, P ＞ 0.05 ), but the mean FA [ ( 301 ± 104 ) × 10 -3, ( 316 ±112) × 10-3 ] value increased ( Z = - 2.794, P ＜ 0.05 ). The paired-samples t test show that the mean ADC value [ ( 1685 ± 190) × 10-3 mm2/s, ( 1624 ± 180) × 10-3mm2/s] of Grade Ⅲ discs decreased after axial loading, t=3.513, P＜0. 05, Grade Ⅲ, Ⅳdiscs mean FA value [(300±87) ×10-3, (326±87) ×10-3 for Grade Ⅲ and (348 ±67) × 10-3, (351 ± 71 ) × 10-3 for Grade Ⅳ ] increased, t = - 2. 210,- 2.006, P ＜ 0.05. No significant difference existed in Grade Ⅱ , Ⅳ and Ⅴ discs ADC value, all the P ＞0.05. No significant difference existed in Grade Ⅱ and Ⅴ discs FA value, both the P ＞ 0.05. Conclusions Short time axial loading mainly affect the mildly degenerated discs, the ADC value decreases and the disc diffusion ability decreases. No obvious change in ADC value or disc diffusion ability existed in the normal and severely degenerated discs.