I
对比研究
摘要：目的：比较直肠癌术后病理标本与术前MRI （T1WI, T2WI, DWI）和/或CT 显示肿瘤范围的差异，研究各影像模式对直肠癌大体肿瘤体积（GTV）显示的精确性，借此探索各影像模式对直肠癌术前放疗大体肿瘤体积（GTV）勾画的指导意义。
方法：前瞻性入组22例临床分期为T1-4aN－/＋M0拟行TME 手术的直肠癌患者，术前均行盆腔MRI 和/或增强CT 检查。通过MRI （T1WI,
丰田电动车T2WI, DWI）和/或CT 分别测量肿瘤沿肠道纵轴长度（L T1-L ,
汽配城L T2-L , L DWI-L , L CT-L ）
、垂直肠道横轴位肿瘤最宽径（L T1-W , L T2-W , L DWI-W , L CT-W ）和横轴位肿瘤实际面积（A T1, A T2, A DWI , A CT ）
。通过术后病理标本测量对应参数（L path-L , L path-W , A path ）
，将病理参数作为“金标准”，评估各影像测量的精确性。
结果：L path-L 为（4.06±1.14）cm， L T1-L 、L T2-L 、L DWI-L 、L CT-L 分别为（3.91±1.51）、（4.62±1.41）、（3.39±1.05）、（3.94±1.23）cm，与L path-L 的相关系数分别为0.688、0.635、0.688、0.720(P＜0.05)；Bland-Altman分析显示T2WI测量结果存在平均6mm高估，T1WI、DWI、CT测量结果存在1mm至6mm不同程度的低估。病理横截面肿瘤最宽径（L path-W ）为（2.56±0.94）cm，L T1-W 、L T2-W 、L DWI-W 、L CT-W 分别为（3.62±0.99）、（3.66±0.76）、（3.23±0.58）、（3.64±1.04）cm，测量结果存在平均5.1至11.1mm的高估。肿瘤病理实际面积（A path ）为（4.30
±2.83 ）cm2，A
T1、A
T2
、A
新一代奔驰sDWI
、A
CT
分别为（8.98±3.90）、（8.99±3.43）、
（8.41±3.09 ）、（9.63±4.40）cm2，各影像测量实际面积存在2倍左右程度高估。
suv比较结论：通过术后病理参数作为“金标准”的比较研究发现，采用MRI和CT定义直肠癌肿瘤范围时，在病变长度方面，T2WI存在平均6mm 的高估，T1WI、DWI和CT存在1mm-6mm的低估，而各影像在最大横截面最宽径的测量结果存在平均5.1mm至11.1mm的高估，实际面积存在2倍左右程度高估。这一结论对直肠癌术前高精放疗尤其是GTV推量行高剂量放疗时GTV的精确勾画有一定的指导意义。因此，在逐层影像勾画直肠癌GTV时可适当考虑内收范围，在最顶端和最底端层面影像GTV勾画时也无需过度上下外延（考虑常用影像扫描层厚）。
关键词：直肠癌；病理标本；磁共振影像；计算机断层影像；大体肿瘤体积
I I
COMPARISON OF RECTAL CANCER TUMOR
VOLUME PARAMETERS MEASURED ON MRI SEQUENCES AND CT WITH THOSE ON
PATHOLOGICAL SEPCIMEN
Liu Yuanyuan(major in radiation oncology)
Directed by Professor Zhu Suyu
Abstract:Objective: To compare gross tumor volume (GTV) parameters measured on MRI sequences (T1WI, T2WI, DWI) and / or CT with those on pathological specimen with rectal cancer for assessing GTV delineation accuracy based on MRIs and CT.
Methods: Twenty two patients with stage cT1-4aN－/＋M0 rectal cancer were prospectively enrolled. MRI sequences including T1WI, T2WI and DWI, and/or CT of the pelvis were performed before operation. Volume parameters such as tumor length along the rectal axis (L T1-L, L T2-L, L DWI-L, L CT-L), Maximum tumor width perpendicular to rectal axis (L T1-W, L T2-W, L DWI-W, L CT-W) and tumor actual area in that perpendicular plane (A T1, A T2, A DWI, A CT) were measured on T1WI, T2WI, DWI and CT respectively for each patient. The respective pathological parameters (L path-L , L path-W and A path ) were also measured on surgical specimen after total mesorectal excision. Those two kinds of parameter values measured on imaging and pathology were statistically compared and accuracy appraisal was performed with pathological parameters as “gold standard”.
III
Results: The mean L path-L was 4.06±1.14 cm, The mean L T1-L, L T2-L, L DWI-L and L CT-L were 3.91±1.51, 4.62±1.41, 3.39±1.05 and 3.94±1.23 cm respectively. The correlation coefficients were 0.688, 0.635, 0.688 and 0.720 (P < 0.05). Bland-Altman analysis shows that there was an average 6 mm overestimation on T2WI, and 1mm to 6 mm underestimation on T1WI, DWI and CT in length values compared with those measured on surgical specimen. The mean L path-W was 2.56 ±0.94 cm. The mean L T1-W, L T2-W, L DWI-W and L CT-W were 3.62±0.99, 3.66±0.76, 3.23±0.58 and 3.64±1.04 cm respectively. The magnitude of mean overestimation ranged from 5.1mm to 11.1 mm. The A path was 4.30 ± 2.83 cm2. The A T1, A T2, A DWI and A CT were 8.98±3.90, 8.99±3.43, 8.41±3.09 and 9.63±4.40 cm2 respectively, and which double overestimated tumor area in the perpendicular rectal plane.
Conclusions: With rectal cancer volume parameters measured on surgical specimen as the “gold standard” for comparison, T1WI, DWI and CT tended to underestimate and T2WI overestimate longitudinal length of rectal cancer within the magnitude of 6 mm. The mean maximum width measured on MRIs and CT overestimated horizontal tumor width in the range of 5.1 to 11.1mm, and the tumor areas in the horizontal plane were double overestimated. The findings in this study implies 高尔夫gti改装图片
that GTV delineation based on MRI or CT for rectal cancer “boost” preoperative radiotherapy should be conservative lateral to I V
rectum, and longitudianl slice extension was not necessary considering mixed results of the magnitude of under or over tumor length estimation and scan thickness.
Keywords: Rectal cancer Pathological specimen MRI Computer-assisted tomography Gross tumor volume (GTV) delineation
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