| Objective: By observing the application of target delineation and thechanges of apparent diffusion coefficient (ADC) value before, during and afterradiotherapy in using chest MR diffusion-weighted imaging (DWI), and toexplore the application of MR diffusion weighted imaging in preciseradiotherapy and evaluation of the effect in esophageal carcinoma.Methods: Eighty-eight cases of esophageal patients with potentiallyradical radiotherapy and confirmed by pathology from March2010to January2012were collected in this study. All patients were taken esophagogram andesophagoscope. Fixed by a heat plastic device, each patient was examined byCT and MRI DWI scan as same as the radiotherapy treatment position. Theobtained images were transmitted to treatment planning system by local areanetwork and fusioned with CT in accordance with bony structures by Syntegrasoftware, drawing the outline of the gross tumor volume (GTV) anddeveloping radiation therapy planning. Prescription dose:54-61.2Gy. Allpatients were examined with conventional MRI (T1WI, T2WI sequence) anddiffusion-weighted imaging scans (DWI) before and after radiotherapy,35patients among of them were reviewed chest conventional MRI scan and DWIweekly, and then once a mouth after radiotherapy, following up1-3months.(1) The tumor lengths were compared by esophagogram, esophagoscope, CT,original DWI(DWI-ORI) and DWI transmitted(DWIT). Also the tumortransverse diameters were compared between CT and DWIT image.(2) To redetermine mediastinal lymph nodes which is metastasised accordingto CT and DWI respectively, and compare the difference of ADC values ofmetastasised lymph nodes diagnosed by CT and DWI with which diagnosedby DWI only, and observe the differences in clinical stages. (3) For each patient, two separate GTVs were defined, one based on CT(GTV-CT) and another one based on MRI DWI (GTV-DWIT) respectively.To compare the size of volume and the diversity of upper and lower bounds ofGTV-CT and GTV-DWIT.(4) To measure the length of tumor and the ADC value of normal tissue andtumor using DWI before and after radiotherapy.(5) Following up1-3months, to compare the difference of ADC values oftumor between1group(the patients whose high signal disappeared in DWIsequences) and2group(the patients whose high signal did not disappeare inDWI sequences). And35patients reviewed weekly magnetic resonance, weredynamically observed the tumor length and ADC value. To analyse the actionof MRI furtherly in Prognosis.(6) To evaluate the efficacy of the esophagus according to esophagogram afterradiotherapy and observe the influence of the ADC value. Statistical analysiswas performed using an SPSS statistical package (Version13.0).Results:(1) The esophageal lesions and lymph nodes of four patients hadno signal in DWI sequences.(two of the four is early esophageal cancer).Tumor lengths of esophagogram, esophagoscope, CT, DWI-ORI and DWITwere:5.64±2.10cm,5.60±2.44cm,8.00±2.91cm,5.66±1.92cm and6.23±2.70cm respectively in Remaining84patients. The lengths between CTand esophagogram, CT and esophagoscope, CT and DWI-ORI, CT and DWIThad statistical significance, P<0.001respectively. The greatest diameters oftumor shown on CT and DWIT were3.67±0.93cm and3.24±1.03cmrespectively. There were statistical significance between CT and MRI.P=0.001. The diameters and ADC values were negatively correlated (P=0.002,correlation coefficient r=-0.335).(2)145lymph nodes were assessed positiveon CT image,115on the MRI DWI image and94on both. DWI imageexcluded51positive lymph nodes assessed by CT(14of them located in Aorta-pulmonary artery window); also confirmed21negative lymph nodesexcluded by CT (9of them were paraesophageal lymph nodes). The averageADC value of lymph nodes assessed by CT and DWI was 1.74±0.46×10-3s/mm2, and that2.17±0.67×10-3s/mm2by MR only. There werenot statistical significance. The addition of MRI information altered theclinical stage in17patients(17/84). One patient's therapentic purpose hadbeen changed.(3) The volumes of GTV-CT and GTV-DWIT were45.78±26.48cm3and40.87±24.66cm3respectively. There were significant difference between thevolume of GTV-CT and GTV-DWIT. P<0.001. On the basis of DWIT, CTover rate average1.12cm on the upper bound of tumor in64patients andunderrate average0.7cm in12patients; CT overrate average1.35cm on thelower bound of tumor in61patients and underrate average1.00cm in12patients.(4)(b=600) The ADC value of normal esophageal tissues is3.13±0.45×10-3s/mm2, The ADC value of tumor esophageal tissues is1.68±0.44×10-3s/mm2;(b=1000) The ADC value of normal esophageal tissuesis2.09±0.42×10-3s/mm2, The ADC value of tumor esophageal tissues is1.42±0.38×10-3s/mm2. In83patients (except4patients who had no signs inDWI image and1patient stopped radiotherapy because of bone marrowsuppression), the length of tumor was5.66±1.92cm in DWI-T image beforeradiotherapy and2.32±2.23cm after radiotherapy. There were statisticalsignificance. P=0.0003. The ADC value of tumor is1.68±0.44×10-3s/mm2before radiotherapy and2.62±0.67×10-3s/mm2after radiotherapy. There werestatistical significances. P<0.0001.35patients among of them were weeklyreviewed chest conventional MRI scan and DWI, the lengths of tumorcompared between them. The ADC values compared too. Along with theincrease of number of radiotherapy, the length shortened and ADC valuesincrease gradually.(5) The average ADC value of tumor was increased1.08±0.53×10-3s/mm2in1group before and after radiotherapy, and0.87±0.47×10-3s/mm2in2group,P=0.003, there were significant differences.(6) Assessment of Efficacy: in87patients (except1patient stoppedradiotherapy because of bone marrow suppression), esophagogram: complete remission (CR)54patients, partial remission (PR)32patients, no remission(NR)1patient. In15of54patients still had high sign in DWI image,19of32had no high sign in DWI image. The NR patient still had high sign in DWIimage. So MRI:CR58patients, PR29patients, the ADC value of CR patientsassessed by esophagogram was lower than that of CR patients assessed byMRI after radiotherapy, the ADC value of PR patients assessed byesophagogram was lower than that of PR patients assessed by MRI afterradiotherapy.Conclusion: The tumor lengths measured by different testing methodshad differences. Tumor lengths measured on DWI-ORI and esophagogramhad the optimal approximation. GTV volumes sketched by two methods haddifferences. DWI can be used as important information for determining thetarget area. DWI was easy to find paraesophageal lymph nodes. By theadditional MRI information, the Target range and clinical stage were alerted insome patients of esophageal carcinoma. The ADC value of normal esophagealtissues was higer than that of tumor and mediastinal metastatic lymph node.MRI could provide important clinical information in evaluating theradiotherapy effect and estimating prognosis early for esophageal cancer. |
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