| Objective To discuss the clinic value of 3.0T MRI combined DWI and DCE-MRI in the selection of early diagnosis, accurate pre-operational staging and surgical method of rectal cancer, as well as its correlation with staging, typing and differentiating of pathology.Materials and Methods1.General information and scanning method:Philips Achieva 3.0T MRI,SENSE-XL-TORSO 8-channel phased-array surface coils.60 cases of rectal cancer patients underwent conventional sequences,high-resolution MRI, diffusion-weighted imaging and conventional enhanced scan, which selected 30 cases plus for dynamic contrast enhanced.Take polyethylene glycol for bowel preparation on one day before the examination; fasting 8 hours before the examination;intramuscularly the patients with 10 mg anisodamine 10 minutes before the examination.2.DWI:Use spin echo-echo planar imaging(SE-EPI) sequence,b takes 0 and800s/mm2,TR/TE=2750ms/min,FOV 400mm×350mm,matrix 180×256, NSA=2, slice thickness 6mm, slice gap 1mm.Measure the apparent diffusion coefficient(ADC)value of rectal cancer; compare the correlation between the prognostic factors(e.g.pathological pattern, differentiated degree, whether the tumor grows by breaking through the intestinal wall, whether lymph gland is metastasis, whether mesorectal fascia is involved, gross types of tumor, location of tumor, age and gender) of rectal cancer and the average ADC value of tumor.3. 60 cases of patients with rectal cancer were use conventional sequences and HR MRI with and without DWI,and use these two methods for preoperative staging of tumors,the result of postoperative pathology is regarded as a gold standard. Compare the accuracy, sensibility, specificity, positive predictive value and negative predictive value of these two staging method, as well as the consistency between these methods and postoperative pathology.Evaluate the affected situation of mesorectal fascia,the result of postoperative pathology is regarded as the gold standard.Compare the accuracy of evaluation and consistency of postoperative pathology result. Measure thedistance between the inferior border and anal verge of lump from the sagittal view,and compare it to the result of pathologic sample after operation.4.DCE-MRI:e-THRIVE_dyn_BH SENSE axial scanning,select Gd-DTPA as contrast agent, and inject it with high pressure injector from elbow vein.The injection flow rate:3.0ml/s,injection dose:0.1mmol/kg.Compare the rectal cancers of different differentiated degree and the time-intensity curve(TIC) of lymph node,observe and summarize the TIC curve characters and its regularity.Measuring the signal indensity of peak enhancement(SIpeak),the time to peak(TTP),the starting signal strength(S0)and the starting time of strengthening(T0), and take them into comparison.5.Statistical Methods:SPSS19.0 software package is adopted to statistically analyze data,the measurement data is shown in the form of(`x ± s),the comparison adopts t test of independent sample mean, t test of paired sample mean and one-way analysis of variance, etc.Consistency adopts Kappa inspection,while correlation is analyzed by Pearson.Test level α= 0.05, with P <0.05 was considered to be statistically significant.Results1.The averaged ADC value of rectal cancer is of statistical significance with differentiated degree(P=0.000), pathology T1-2 and T3-4(P=0.015), pathology N0 and N1-2(P=0.001), affected mesorectal fascia and unaffected one(P=0.014). The averaged ADC value of rectal cancer has no statistical significance with gross type of tumor(P=0.971), tumor position(P=0.960), gender(P=0.592). There is no significant correlation between the average ADC value and age(r=0.038) of rectal cancer.2. The methods Convention + high resolution MRI as well as convention + high resolution MRI + DWI sequence are respectively adopted, and the accuracy of preoperative T staging is 76.67% and 88.33%. Compared with the consistency of postoperative result, the Kappa value is 0.628 and 0.814. The sensibility, specificity,positive predictive value, negative predictive value of these two methods on T1 staging is 50.00% and 75.00%, 100.00% and 100.00%, 100.00% and 100.00%,96.55% and 98.25%; on T2 staging is 75.00% and 85.00%, 90.00% and 95.00%,78.95% and 89.47%, 87.80% and 92.68%; on T3 staging is 82.76% and 93.10%,77.42% and 87.10%, 77.42% and 97.10%, 82.76% and 93.10%; and on T4 staging is71.43% and 85.71%, 94.34% and 98.11%, 62.50% and 85.71%, 96.15% and 98.11%.The accuracy of these two methods on pre-operation N-staging is 60.00% and 71.16%respectively, and compared to the consistency of preoperative pathology result, the Kappa value is 0.331 and 0.517 respectively. The sensitivity, specificity, positive predictive value, negative predictive value of these two methods on N0 staging is57.14% and 71.43%, 74.36% and 79.49%, 54.55% and 65.22%, 76.32% and 83.78%respectively; on N2 staging is 50.00% and 66.67%,87.04% and 92.59%, 30.00% and50.00%, 94.00% and 96.15%. The accuracy of high resolution MRI on measuring the affected situation of mesorectal fascia is 91.67%, and compared to the consistency of post-operational pathology result, the Kappa value is 0.798. Compared the distance between the inferior border of tumor to anal verge measured under the high resolution MRI, with the measuring result of gross sample after operation, the difference is not statistically significant(P=0.037).3.According to the appearance time of tumor intensity peak as well as the quitting time of contrast agent, the time-single intensity curve can be approximately divided into three types: type I, type II and type III. In type I, there is no clear peak, and the whole process is at a slowly rising state; in type II, the signal rises significantly at the early stage of enhancement. The rising range slows down to a peak level. After the peak, there is a platform stage; in type III, the signal rises significantly at the early stage of enhancement. After reaching at the peak, the signal declines gradually. In these three types, the TIC curve of rectal cancer presents differently without certain order. Under differentiated degree, the SIpeak-S0, TTP-T0 value of rectal cancer is different. With the declining of tumor differentiated degree, the SIpeak-S0 rises gradually while TTP-T0 also lengthens gradually, but the difference is not statistically significant.(P>0.05)Conclusion1. The average ADC value of rectal cancer is of certain correlation with the pathological type, differentiated degree of tumor, T, N staging of tumor, and infiltration state of mesorectal fascia. Under the condition where the differentiated degree of tumor decreases, infiltration degree increases, the lesion range breaks through the intestinal wall, lymphatic metastasis and the mesorectal fascia is affected,the ADC value declines significantly. The average ADC value of rectal cancer is not statistically significant with the gross type of tumor, tumor position, age and gender.Therefore, the ADC value of tumor can be regarded as a quantitative index to evaluate tumor invasion and prognosis.2. MRI convention + high resolution + DWI sequence is conductive to the diagnosis of rectal cancer and improving the accuracy of TN staging. It is also conductive to ensuring the invasion degree of tumor to intestinal wall and other organs nearby. This method has high accuracy on T staging of tumor but normal accuracy on N staging. Thus, it plays an important role in the diagnosis of tumor and preoperative staging. In addition, high resolution MRI can either evaluate the affected condition of mesorectal fascia, or accurately measure the distance between the inferior borders of tumor to anal verge.3. MRI dynamic enhancement scan is conductive to the diagnosis of rectal cancer,which can not only reflect the morphological characteristics of lesion, but presents the dynamic process of contrast agent when it inflows into or outflows the tumor. Further,it also provides the information of blood circulation condition of the local tumor. |
PDF Full Text Request