| Rectal cancer is a common malignant tumor in digestive tract. In recent years, with change of people’s way of life and diet structure, aggravation of environmental pollution, increasing aging population and development of medical technology, Its incidence is increasing rapidly and becomes a serious threat to people’s life and healthy.Rectal cancer prognosis depended mainly on treatment plan, tumor type, tumor resectability and appropriate neoadjuvant treatment, evaluation of these aspects relied on imaging examination. Multi-slice CT (MSCT) and its postprocessing techniques had been widely used for preoperative staging of rectal cancer and clinical assessment, and had been recognized by clinician consistently. But at present rectal cancer imaging evaluation and research mainly focused on gross morphological and anatomical structure, how to evaluate the microcirculation of rectal cancer, predict its biological characteristics, guide the choice of treatment, estimate prognosis before operation is the problem we are facing.Recent studies showed that CT perfusion imaging (CTPI) as a non-invasive functional imaging technology, according to the intake of iodine contrast agent of time density curve (TDC) and different mathematical models, It could calculate artery flow (AF), blood flow (BF), blood volume (BV), permeability surface (PS) parameters of blood perfusion, we could obtain perfusion maps and evaluate perfusion state of tissues and organs on the basis of pseudo color processing and image reconstruction. So it played an important role in evaluation of tumor angiogenesis, chemotherapy and radiotherapy, monitoring of tumor recurrence and prognosis.With the development of medical imaging equipment and scanning technology, the direction of development of medical imaging was from traditional morphology on the basis of anatomical pathology to molecular level to reflect functional imaging. CT perfusion imaging was a functional imaging technique for noninvasive assessment of tissue perfusion in vivo, in recent years, Many scholars proved that it had important clinical value in assessment of biological behavior and prediction of treatment efficacy in perfusion of lung cancer, liver cancer, brain tumors. Rectum was cavity organ, but relatively fixed position, after appropriate bowel preparation, It had good density contrast with surrounding tissue, Respiratory movement and intestinal peristalsis had small effect on rectum, Rectal running was vertical to CT scanning direction, measurement was relatively easy, so it was relatively suitable for perfusion.Since machines limit, single section or part sections of tumor perfusion were often used, but which could or couldn’t represent the whole tumor tissue, it was questionable.640-slices CT had the most wide 16cm detector, It could realize the whole tumor and organ perfusion imaging. It was rarely reported on the whole tumor perfusion imaging of rectal cancer at home and abroad. Based on the above theory and research focus, Application on the whole tumor perfusion imaging of rectal cancer was prospectively studied on 640-slices CT.This study aimed to explore the feasibility of CT perfusion in rectal cancer using 640-slices CT, to evaluate the consistency between quantitative CT perfusion measurements of rectal cancer obtained from single maximal section and from average of the whole tumor, and to explore the relationship between perfusion parameters and biological behavior and tumor markers of rectal cancer. It was expected to provide more valuable information for preoperative evaluation and chemotherapy radiotherapy efficacy monitoring of rectal cancer.Part I:Assessment of consistency of the whole tumor and single maximal section with multiple position perfusion measurement of rectal cancer on 640-slices CTObjective:To explore the feasibility of CT perfusion in rectal cancer using 640-slices CT, and to evaluate the consistency between quantitative CT perfusion measurements of rectal cancer obtained from axial, sagittal, coronal single section with maximal dimension and from average of the whole tumor, and to compare intra-and inter-observer consistency of two analysis methods. It will provide a reliable basis for selection of measurement method and accuracy of measurement value.Materials and methods:Fouty-five patients with pathologically confirmed rectal cancer were examined prospectively with 640-slices CT perfusion imaging, and the whole tumor perfusion images were obtained. Perfusion parameters including blood flow (AF), blood volume (BV), blood flow (BF), permeability surface (PS) were measured. There were two measurement methods:single maximal section measurement method (i.e. as a method of region of interest in maximal tumor section delineation of tumor contour) and the whole tumor measurement (i.e. delineation of tumor contour layer by layer and then average of multiple sections). Each tumor single maximal section measurement of axial, sagittal, coronal maximum section and whole tumor measurement (in axial position) perfusion parameter values were obtained by one radiologist. Intra-observer consistency was evaluated by comparing repeated measurement by the same radiologist using two methods in axial position after two months, perfusion measurement were done by another radiologist independently to assess inter-observer consistency of two methods in axial position. The means from single maximal section measurement and the whole tumor measurement method were compared using independent samples t test, Several groups of samples mean were compared using single factor analysis of variance(ANOVA), For not satisfied normality distribution types of sample using Wilcoxon rank sum test analysis. Spearmen correlation was used to analysis the relationship of value of perfusion parameters between maximal section in different position and the whole tumor. Intra-and inter-observer consistency of repeated measurements was compared using paired t test.Results:1. The perfusion parameters AF, BV, BF and PS obtained by whole tumor perfusion analysis were (209.25±63.56)ml/min/100ml, (31.82±6.69)ml/100g, (16.78±5.02) ml/min/100ml and (7.02±1.84) ml/min/100ml.2. The perfusion parameters AF, BV, BF and PS obtained by single maximal section analysis in axial position were (212.00±66.61)ml/min/100ml, (32.47±6.63)ml/ 100g, (17.20±5.04) ml/min/100ml and (7.15±1.75) ml/min/100ml. No significant difference was observed between means of the perfusion parameters with the whole tumor method, P were 0.841,0.641,0.690, and 0.448, respectively.3. The perfusion parameters AF, BV, BF and PS obtained by single maximal section analysis in sagittal position were (203.94±62.46)ml/min/100ml, (33.75±7.37)ml/100g, (17.28±5.01) ml/min/100ml and (7.18±1.74) ml/min/100ml. No significant difference was observed between means of the perfusion parameters with the whole tumor method, P were 0.690,0.123,0.583, and 0.424, respectively.4. The perfusion parameters AF, BV, BF and PS obtained by single maximal section analysis in coronal position were (207.58±70.56)ml/min/l00ml, (32.61±6.95) ml/100g, (17.29±5.08) ml/min/100ml and (7.19±1.71) ml/min/100ml. No significant difference was observed between means of the perfusion parameters with the whole tumor method, P were 0.906,0.429,0.635, and 0.446, respectively.5. The values of different perfusion parameters (AF, BV, BF and PS) in axial, sagittal, coronal maximum section had obvious correlation with that of the whole tumor. The correlation coefficient of AF value in axial, sagittal, coronal maximum section with the whole tumor were 0.972,0.906,0.924, respectively; the correlation coefficient of BV were 0.900,0.858,0.899, respectively; the correlation coefficient of BF were 0.985,0.978,0.981, respectively; the correlation coefficient of PS were 0.987,0.983,0.983, respectively.6. The perfusion parameters values of AF, BV, BF and PS had no significant difference obtained by intra-observer for two times with the whole tumor analysis, P were 0.901,0.849,0.646, and 0.519, respectively; with single maximal section analysis, P were 0.601,0.654,0.490, and 0.399. respectively.7. The perfusion parameters values of AF, BV, BF and PS had no significant difference obtained by inter-observer with the whole tumor analysis, P were 0.813, 0.608,0.771, and 0.468, respectively; with single maximal section analysis, P were 0.771,0.424,0.675, and 0.283. respectively. It showed that the whole tumor perfusion analysis method was better repeatedly.Conclusions:1.640-slices CT perfusion imaging could reflect microvascular distribution of rectal cancer to some extent2. The values of different perfusion parameters in axial, sagittal, coronal maximal section had good correlation with that of the whole tumor perfusion analysis, axial was more accurate relatively. There was no statistically different between single maximal section and the whole tumor perfusion analysis.3. The data of whole tumor perfusion measurement was relatively accurate and had smaller differences than that of single maximal section measurement. The whole tumor perfusion measurement apparently improved intra-observer and inter-observer consistency and repeatability. It was the best measurement method of perfusion imaging in rectal cancer.Part Ⅱ:Research of the whole tumor perfusion imaging parameters in evaluation of biological behavior of rectal cancer on 640-slices CTObjective:To investigate the relationship between the whole tumor perfusion imaging parameters and biological behavior of rectal cancer, and tumor markers of rectal cancer using 640-slices CT. It will provide a valuable basis for treatment options and predicting curative effect of rectal cancer.Materials and methods:Fouty-five patients with pathologically confirmed rectal cancer were examined prospectively with 640-slices CT perfusion imaging, and the whole tumor perfusion images were obtained. The whole tumor perfusion parameters including blood flow (AF), blood volume (BV), blood flow (BF), permeability surface (PS) were measured. To analysis the relationship between different perfusion parameters and staging, differentiation, tumor length, thickness, degree of intestinal wall circumferential invasion of rectal cancer. Two groups of samples mean were compared using independent samples t test, Several groups of samples mean were compared using single factor analysis of variance(ANOVA), For not satisfied normality distribution types of sample using Wilcoxon rank sum test analysis. Spearmen correlation was used to analysis relationship between different perfusion parameters and different serum tumor markers, such as CA125, CA153, CA199, CA724 and CEA.Results:1. There was significant difference in PS value among different T staging, clinical stage, lymph node metastasis and different differentiation degree of rectal cancer, P were 0.008,0.000,0.000, and 0.008, respectively.2. There was significant difference in BF value among different T staging and different length and different degree of intestinal wall circumferential invasion of rectal cancer, P were 0.001,0.009, and 0.018, respectively.3. There was significant difference in AF value among different thickness of rectal cancer (P=0.029). There was significant difference in BV value among different degree of intestinal wall circumferential invasion of rectal cancer (P=0.030).4. AF, BV, BF, PS values were not statistically significant in different age, sex, and different site of rectal cancer (P> 0.05).5. PS value in CEA positive group and CA199 positive group were greater than those of negative groups, the difference was statistically significant between two groups, P were 0.007,0.020, respectively. BF value in CA199 positive group was lower than that of negative group, the difference was statistically significant between two groups (P=0.046).6. PS value was positively correlated with serum CEA value, r= 0.401, P=0.006, BF was negatively correlated with serum CA199, r=-0.388, P=0.008, BV was negatively correlated with serum CA199, r=-0.491, P=0.001.Conclusions:1.640-slices CT perfusion imaging could reflect hemodynamic change of rectal cancer. CT perfusion parameters could evaluate biological behavior of rectal cancer in vivo. It could provide a reliable basis for clinical treatment and prognosis evaluation scheme of rectal cancer.2.640-slices CT perfusion imaging parameters of the whole tumor were related to serum tumor markers CEA and CA199. The combined application of two methods would have an important value for diagnosis and disease monitoring of rectal cancer. |
