| Part I Correlation of ADC value between primary tumor site and cervical lymph nodes nasopharyngeal carcinomaObjectiveBy diffusion-weighted imaging with background body signal suppression(DWIBS) detect the apparent diffusion coefficient ADC) value of primary tumors5metastatic cervical lymph nodes and small lymph nodes(5-10mm) separately. Analysis of relation between three groups ADC value.Materials and Methods1. SubjectsCollected 42 patients in our hospital department of otolaryngology and oncology between December 2013 and November 2014, that were histopathologically confirmed nasopharyngeal carcinoma with untreated.31 men and 11 women, age range 20 to 82 years old, mean age 47 years old. All patients underwent conventional MR imaging scan and diffusion-weighted imaging with background body signal suppression scan.The study procedure and consent forms were approved and reviewed by the ethics committee before study initiation. All patients signed the informed consent.2. MR imaging equipmentsPatients were imaged using a 3.0T MRI scanner(Achieva 3.0T, Holland Philips) and head-neck 16-channel phased-array surface coil.3. MR Imaging and DWIBS canning sequence and parametersPatients were required supine position and prohibited swallowing. All patients needed MR imaging and DWIBS scan, scanning neck range from cavernous sinus to the upper edge of the manubrium sterni.The main parameters of routine MR imaging for each sequence:(1) T1 weighted image (T1WI),TR/TE530ms/20ms, Slice thickness=5mm, interval=1mm, FOV=200mmx 180mm, Matrix=256×256; (2) T2 weighted image(T2WI), TR/TE3000ms/80ms, Slice thickness=5mm, interval=1mm, FOV=200mmx 180mm, Matrix=256×256; (3) Short Tl inversion recovery(STIR), TR/TE3300ms/80ms, Slice thickness=5mm,interval=1mm, FOV=200mmx200mm, Matrix=256×256; After injecting Gd-DTPA via cubital vein, the axial, coronal and sagittal contrast-enhanced MR imaging were scanned.The main parameters of DWIBS sequence:TR/TE9000ms/60ms,Slice thickness=2mm, interval=lmm, FOV=190mmx 190mm, Matrix=256×160. Diffusion sensitive factor(b value):b=0, b=800 s/mm2. Before enhancement scanning,we needed diffusion-weighted imaging with background body signal suppression scan. Moreover, the scanning scope was similar to conventional MRI. The sequence used the sensitivity encoding technique and the single shot SE-EPI sequence. The application of STIR was fat suppression.4. Imaging analysis and data evaluationImaging and data evaluation were analysed by two experienced MR diagnosis radiologists. Reviewers were blinded to clinical information. Nasopharyngeal primary tumors, metastatic lymph nodes and small lymph nodes (5-10mm) were as three groups needed to be observed and measured. Moreover, retropharyngeal node and cervical lymph node(Ⅱ Ⅲ Ⅴ) were selected region. Analysis of three groups on the signal characteristics in DWIBS. Combined with conventional and enhanced MR images to determine the location of the selected area measured on DWIBS and ADC maps. The mean ADC value was direct measurement on the ADC map. The results of quantitative data were averaged for analysis from two measurements.Statistical MethodSPSS 13.0 software package was applied to conduct the data of the study. Measurement data were expressed as mean±standard deviation (x±s) indication. The mean ADC value of primary tumor group, metastatic cervical lymph node group and small lymph node group were used one-way ANOVA analysis. Statistical tests were two-tailed test method applying a side and significant level of statistical significance test P<0.05.ResultsDWIBS showed the mass-type nasopharyngeal carcinoma clearly, but poorly displayed the mucosa-type. Metastatic and small lymph nodes were high signal clearly. The mean ADC value of primary nasopharyngeal carcinoma, metastatic lymph nodes and small lymph nodes was 0.805±0.072×10-3mm2/s,0.783±0.081×10-3mm2/s and 0.791±0.062×103mm2/s respectively. There was no significant difference among the three groups(P>0.05).ConclusionsDWIBS displayed the mass-type nasopharyngeal carcinoma and lymph nodes distinctly. This study suggests that part of lymph nodes may be an invasion of tumor cells in different degrees and their structure may be consistent with the primary tumor pathology tissue. Because of tumor infiltration, water molecule is restricted diffusion. ADC value is low which narrows the gap between benign and malignant lymph nodes. Therefore, by exploring the correlation of ADC value among primary tumor,metastatic lymph nodes and small lymph nodes,we may speculate reversely that these lymph nodes are benign or malignant. This method will provide complementary diagnosis.Part Ⅱ Comparative study of MRI,DWIBS and SPECT/CT in diagnosis of skull base bone invasion in nasopharyngeal carcinomaObjectiveThis study was designed to analyze the diagnostic value of MRI, DWIBS and SPECT/CT for skull base bone invasion in nasopharyngeal carcinoma and to evaluate the capability of three examined methods for skull base bone destruction.Materials and Methods1. SubjectsCollected 40 patients in our hospital department of otolaryngology and oncology between December 2013 and November 2014, that were histopathologically confirmed nasopharyngeal carcinoma with untreated.30 men and 10 women, age range 26 to 82 years old, mean age 49 years old. All patients underwent conventional MR imaging,DWIBS and SPECT/CT scan. These three examination ways were no more than 7 days. The study procedure and consent forms were approved and reviewed by the ethics committee before study initiation. All patients signed the informed consent.2. MR imaging equipmentsPatients were imaged using a 3.0T MRI scanner(Achieva 3.0T, Holland Philips) and head-neck 16-channel phased-array surface coil. Patients were scanned using a SPECT/CT device(American, GE infiniaVC Hawkeye) with a low energy and high resolution collimator.3. MR Imaging,DWIBS and SPECT/CT scanning sequence and parametersPatients were required supine position and prohibited swallowing. All patients needed MR imaging and DWIBS scan, scanning neck range from cavernous sinus to the upper edge of the manubrium sterni.The main parameters of routine MR imaging for each sequence:(1) T1 weighted image (T1WI),TR/TE530ms/20ms, Slice thickness=5mm, interval=1mm, FOV=200mmx 180mm, Matrix=256x256; (2) T2 weighted image(T2WI), TR/TE3000ms/80ms, Slice thickness=5mm, interval=1mm, FOV=200mmx 180mm, Matrix=256x256; (3) Short T1 inversion recovery(STIR), TR/TE3300ms/80ms, Slice thickness=5mm,interval=1mm, FOV=200mmx200mm, Matrix=256x256; After injecting Gd-DTPA via cubital vein, the axial, coronal and sagittal contrast-enhanced MR imaging were scanned.The main parameters of DWIBS sequence:TR/TE9000ms/60ms,Slice thickness=2mm, interval=1mm, FOV=190mm×190mm, Matrix=256×160. Diffusion sensitive factor(b value):b=0, b=800 s/mm2. Before enhancement scanning, we needed diffusion-weighted imaging with background body signal suppression scan. Moreover, the scanning scope was similar to conventional MRI. The sequence used the sensitivity encoding technique and the single shot SE-EPI sequence. The application of STIR was fat suppression.Bone scintigraphy (SPECT/CT):imaging agent:99mTC-MDP provided by the China Institute of Atomic Energy, radiochemical purity greater than 95%, its physical and chemical properties and biodistribution in vivo imaged standards in line. Imaging equipment and conditions:using the GE infiniaVC Hawkeye SPECT/CT device from the US, the instrument with a low energy and high resolution collimator, energy peak 140kev, window width 20%, whole body imaging matrix 256×1054, the scanning speed 10cm/min; local imaging matrix 256×256, collecting time 5min. Imaging method:Intravenous injection 99mTC-MDP 925MBq, followed by drinking 500-1000ml, after 2-4 hour instructing patient urination,removing the metal material, and requiring supine position, front or back position.4. Imaging analysis and data evaluation(1) Images and data evaluation were analysed by two experienced MR diagnosis radiologists. Reviewers were blinded to clinical data and images information. There was difference that two reviewers reached an agreement after discussion.Conventional MRI criteria:the normal low signal of the cortical bone of skull base disappeared. The high signal of yellow marrow was replaced by the low signal of tumor tissue and enhanced significantly. Skull base bone including pterygoid area, sphenoid body, clivus, petrous apex, foramen lacerum, pterygopalatine fossa, foramen ovale,foramen rotundum, great wing of sphenoid bone and so on.DWIBS Analysis:skull base bone invasion showed high signal in DWIBS.(2) Images and data evaluation were analysed by two experienced nuclear medicine physicians. Reviewers were blinded to clinical data and SPECT/CT images. There was difference that two reviewers reached an agreement after discussion.SPECT diagnostic criteria:compared with the contralateral or adjacent normal bone, the radioactivity distribution of skull base bone was significantly increased (abnormal uptake) or defect.CT positioning diagnostic criteria:the cancellous bone of skull base was sparse or destruction, and the cortical bone was interruption, defect or sclerosis.(3) Histology results from biopsy are the gold standard for confirming skull base bone invasion in NPC. However, because of the complexity of the skull base, detailed histological results could not be obtained. Thus, the study were made for 30 patients with nasopharyngeal carcinoma using follow-up MR imaging after therapy.5. Statistical MethodSPSS 13.0 software package was applied to conduct the data of the study. The proportion of positive findings of skull base bone invasion was calculated for MRI,DWIBS and SPECT/CT respectively. Based on the final decision,we constructed a contingency table to calculate the sensitivity, specificity and accuracy of three imaging methods. Chi-squared tests were used for statistical analysis. P-values less than 0.05 were considered statistically significant. The accuracy diagnosis of skull base bone invasion were analysed for three methods.6. Results(1) The rates of positive findings of skull base bone invasion for MRI,DWIBS and SPECT/CT were 55%,50% and 72.5% respectively in 40 patients.(2) In the follow-up of 30 cases,19 patients were confirmed as having skull base bone invasion.18 patients with MRI method,15 patients with DWIBS means and 18 with SPECT/CT mapping were detected. The sensitivity, specificity and accuracy of the detection rate of skull base bone invasion for MRI were 94.7%,100% and 96.6% separately. The sensitivity, specificity and accuracy of the detection rate of skull base bone invasion for DWIBS were 78.9%,100% and 86.6% respectively. The sensitivity, specificity and accuracy of the detection rate of skull base bone invasion for SPECT/CT were 94.7%,63.6% and 83.3% separately. There was no statistical difference among the three imaging methods for the sensitivity and accuracy of detecting skull base bone invasion (X2=3.353 and 0.170, P= 0.187 and 0.919). But the methods of MRI and DWIBS were better than SPECT/CT in specificity(X2=9.103, P=0.011).(3) The detection rates of different skull base invasion with MRI,DWIBS and SPECT/CT were 98.4%,78.7% and 68.1%, and it was signicant difference(X2=20.981, P=0.000). MRI method was better than DWIBS and SPECT/CT in the detection of bone invasion on foramen lacerum and greater wing of sphenoid bone, and there was different signicance(X2= 13.000 and 14.494, P= 0.002 and 0.001). The most common site of bone invasion was clivus.ConclusionsMRI displayed the best performance for the diagnosis of skull base invasion in nasopharyngeal carcinoma. DWIBS and SPECT/CT had their own advantages, but thre was some false positive rate and false negative rate. The association of three imaging methods for diagnosing skull base bone invasion is much significant. |
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