MR增强延迟扫描成像在保乳术后俯卧位照射患者瘤床靶区勾画中的应用

目的 基于形变配准探讨保乳术后术腔血清肿不可见或低可见度(CVS≤2)患者行俯卧位照射时MR增强延迟扫描成像在瘤床(LC)勾画中的应用。方法 26例患者入组。分别在俯卧位CT定位图像、俯卧位MR定位T2WI成像及增强延迟2、5、10min的T1WI成像上勾画LC并分别定义为LCCT、LCT2、LC2T1、LC5T1和LC10T1。基于形变配准进行CT与MR图像LC间体积与位置的比较。结果 LCT2、LC2T1、LC5T1、LC10T1体积似均大于LCCT体积,且LC2T1、LC5T1与LCCT间体积差异有统计学意义(均P<0.05)。LC10T1与LCCT间的包含度(DI)、适形指数(CI)、相似度指数(DSC)、靶区中心距离(COM)均似优于LCT2与LCCT、LC2T1与LCCT及LC5T1与LCCT,但差异均无统计学意义(均P>0.05)。结论 基于俯卧位MR定位增强延迟扫描成像勾画低CVS患者LC靶区是可行的,无论是靶区体积大小还是靶区空间位置,基于T1WI增强延迟10min扫描所勾画LC靶区与基于俯卧位CT图像上金属钛夹所勾画的最接近。     

Application of delayed-enhancement MRI in lumpectomy cavity delineation for patients after breast-conserving surgery in prone radiotherapy using deformable image registration

Objective To assess the feasibility of delayed-enhancement MRI in contouring the lumpectomy cavity (LC) for patients with invisible seroma or a low cavity visualization score (CVS≤2) in the excision cavity after breast-conserving surgery (BCS). Methods Twenty-six patients with stageT1-2N0M0 who underwent prone radiotherapy after BCS were recruited. The LC delineated on CT simulation images was denoted as LCCT. The LCs delineated on T2WI, as well as on different delayed phases (2-, 5-and 10-minute) of delayed-enhancement T1WI were defined as LCT2, LC2T1, LC5T1 and LC10T1, respectively. Subsequently, the volumes and locations of the LCs were compared between CT simulation images and different sequences of MR simulation images using deformable image registration. Results The volumes of LCT2, LC2T1, LC5T1 and LC10T1 were all larger than that of LCCT. A statistical significance was found between the volume of LCCT and those of LC2T1 or LC5T1, respectively (both P<0.05). The conformal index (CI), degree of inclusion (DI), dice similarity coefficient (DSC) and the distance between the center of mass of the targets (COM) of LCCT-LC10T1 were better than those of LCCT-LCT2, LCCT-LC2T1 and LCCT-LC5T1, however, there was no statistical difference among them (all P>0.05). Conclusions It is feasible to delineate the LC based on prone delayed-enhancement MR simulation images in patients with low CVS after BCS. Meanwhile, the LCs derived from prone delayed-enhancement T1WI of 10-minute are the most similar with those derived from prone CT simulation scans using titanium clips, regardless of the volumes and locations of LCs.     

CT与MR图像融合在鼻咽癌放射治疗大体肿瘤靶区勾画中的应用

目的探讨CT与MR图像融合在鼻咽癌放射治疗大体肿瘤靶区(GTV)勾画中的临床应用价值。方法40例鼻咽癌患者均在1周内分别进行CT和MR扫描。全部CT和MR图像传送至荷兰核通公司PLATO放射治疗计划系统,进行图像融合。由4位有经验的放疗科医师对CT靶区和CT与MR融合图像大体肿瘤靶区(GTV)进行勾画及评价分析。结果经t检验,融合图像对GTV的显示明显优于单独CT图像。医师对CT-MR融合靶区勾画一致性较好。结论CT-MR图像融合技术有利于鼻咽癌靶区的确定,从而提高临床医师对鼻咽癌大体肿瘤靶区(GTV)进行勾画的准确率,有利于患者的诊治。     

磁共振增强扫描序列在合并阻塞性肺炎或肺不张肺癌放疗靶区勾画价值

目的探讨MRI不同序列在肺癌伴阻塞性肺炎或肺不张(OC)患者中进行靶区勾画的可行性及优势。方法对14例合并OC患者行CT定位和MRI扫描,分别采集CT、T1WI、压脂T2WI、LAVA、LAVA+C图像。将CT、MRI图像在治疗计划系统中融合,分别在CT和MRI上进行靶区勾画GTV-p。结果CT可显示2例患者肿瘤与OC界限,压脂T2WI可显示10例患者肿瘤与OC界限,LAVA可显示12例患者肿瘤与OC界限,LAVA+C可显示10例患者肿瘤与OC界限。压脂T2WI、LAVA、LAVA+C序列间鉴别能力相近(P>0.05),T2WI、LAVA、LAVA+C序列GTV均较CT-GTV明显减小(P<0.05),T2WI_GTV和LAVA_GTV相近(P>0.05)。在所有序列中LAVA+C的GTV值最小。结论MRI的压脂T2WI、LAVA、LAVA+C序列应用于肺癌伴OC患者的放疗靶区勾画提高了精准性,其中LAVA的界限分辨能力较压脂T2WI更好,LAVA+C显示微小血管效果最好。     

保乳术后放疗四维CT呼气末术腔勾画影响因素分析

目的 基于四维CT (4DCT)探讨CT层厚、术腔可见度评分(CVS)及金属夹个数对保乳术后术腔(LC)勾画的影响。方法 术腔放置金属夹数目≥5个的35例保乳术后患者入组行4DCT扫描,全部患者均于T₅₀时相图像上勾画LC。分别依据CT层厚、CVS及金属夹个数对患者进行分组,评价不同组间勾画者间及勾画者自身LC差异(Δ_inter和Δ_intra)及LC间相似度(DSC)。     

Variability in target volume delineation on CT scans of the breast

To determine the intra- and interobserver variation in delineation of the target volume of breast tumors on computed tomography (CT) scans in order to perform conformal radiotherapy.

The clinical target volume (CTV) of the breast was delineated in CT slices by four radiation oncologists on our clinically used delineation system. The palpable glandular breast tissue was marked with a lead wire on 6 patients before CT scanning, whereas 4 patients were scanned without a lead wire. The CTV was drawn by each observer on three separate occasions. Planning target volumes (PTVs) were constructed by expanding the CTV by 7 mm in each direction, except toward the skin. The deviation in the PTV extent from the average extent was quantified in each orthogonal direction for each patient to find a possible directional dependence in the observer variations. In addition, the standard deviation of the intra- and interobserver variation in the PTV volume was quantified. For each patient, the common volumes delineated by all observers and the smallest volume encompassing all PTVs were also calculated.

The patient-averaged deviations in PTV extent were larger in the posterior (42 mm), cranial (28 mm), and medial (24 mm) directions than in the anterior (6 mm), caudal (15 mm), and lateral (8 mm) directions. The mean intraobserver variation in volume percentage (5.5%, 1 SD) was much smaller than the interobserver variation (17.5%, 1 SD). The average ratio between the common and encompassing volume for the four observers separately was 0.82, 0.74, 0.82, and 0.80. A much lower combined average ratio of 0.43 was found because of the large interobserver variations. For the observer who placed the lead wire, the intraobserver variation in volume was decreased by a factor of 4 on scans made with a lead wire in comparison to scans made without a lead wire. For the other observers, no improvement was seen. Based on these results, an improved delineation protocol was designed.

Intra- and especially interobserver variation in the delineation of breast target volume on CT scans can be rather large. A detailed delineation protocol making use of CT scans with lead wires placed on the skin around the palpable breast by the delineating observer reduces the intraobserver variation. To reduce the interobserver variation, better imaging techniques and pathology studies relating glandular breast tissue to imaging may be needed to provide more information on the extent of the clinical target volume.     

55例乳腺癌同侧锁骨上转移淋巴结位置分布对靶区勾画的影响

目的 回顾分析乳腺癌锁骨上淋巴结转移的位置分布,指导锁骨上区域放疗靶区的确定。方法 选择接受螺旋断层CT扫描、诊断为锁骨上转移、可调阅CT图像的乳腺癌患者 55例。选取 1例标准乳腺癌病例,参照锁骨上正常解剖结构位置及比例,将 55例患者转移淋巴结勾画于标准病例定位CT图像上。比较实际淋巴结分布和RTOG及其他文献推荐的锁骨上靶区关系。结果 60%转移淋巴结经病理确诊,64%锁骨上淋巴结转移时存在远处转移。91%和82%患者转移淋巴结中心点分别位于锁骨上内侧和外侧区,66%患者在锁骨下静脉交汇处有转移淋巴结。文献推荐的锁骨上靶区仅可覆盖 20%~42%患者的全部转移淋巴结中心点,RTOG指南仅覆盖26%。中心点超出外界、后界者分别达71%和66%。根据上述淋巴结分布扩大锁骨上靶区照射范围,向外、后侧延伸达自然解剖屏障则可完全覆盖82%患者的全部转移淋巴结中心点。     

图像配准方法在乳腺癌瘤床靶区勾画中的应用进展

乳腺癌保乳术后放疗方案中,瘤床及其靶区的准确勾画至关重要。利用不同医学图像与放疗定位CT图像进行配准能提供更加全面的信息从而辅助医生勾画靶区。根据几何变换性质可将图像配准方法分为刚性和非刚性两大类。由于软组织易形变的特性,刚性配准较难实现非刚性结构的严格匹配,非刚性配准的结果更加符合复杂形变的实际情况。文章旨在综述两类配准方法在乳腺癌瘤床靶区勾画中的应用,分析临床应用中存在的问题,并展望非刚性配准未来的研究方向。     

Research progress on application of image registration methods in target volume delineation of breast tumor bed

Accurate delineation of breast tumor bed and its target volume is of great importance in the planning of postoperative radiotherapy. Registration of different medical images and radiotherapy-oriented CT images can provide more comprehensive information, which can assist radiation oncologists to delineate the target contours. Image registration methods can be divided into the rigid and non-rigid types according to geometrical transformation property. Due to complex and non-rigid deformation of soft tissues, it is difficult to utilize rigid registration to strictly align the non-rigid structures. Non-rigid registration tends to achieve better results. In this article, the application of two types of registration methods in target volume delineation of breast tumor bed was reviewed and the existing problems in clinical practice were analyzed and the research direction of non-rigid registration was prospected.     

基于不同体位定位CT探讨不同勾画者勾画保乳术后部分乳腺外照射靶区差异

目的 比较基于不同体位定位CT下不同勾画者勾画保乳术后部分乳腺外照射(EB-PBI)靶区差异。方法 2016-2017年间27例保乳术后拟行EB-PBI的患者在自由呼吸状态下序贯完成俯卧位及仰卧位模拟定位3DCT扫描。5位勾画者分别在两种不同体位CT图像上基于术腔金属夹完成瘤床(TB) 靶区勾画和临床靶区(CTV) 的构建。比较两种体位不同勾画者间的靶体积、变异系数(COV)、匹配指数(MD)差异。结果 无论仰卧位还是俯卧位时,不同勾画者所勾画TB、CTV均不同(P<0.001、P=0.001、P<0.001、P=0.001)。俯卧位时不同勾画者CTV交集比仰卧位大5.79cm³(P=0.011)。仰卧位时5位勾画者的COVCTV显著大于俯卧位(P=0.014)。仰卧位时5位勾画者的MDTBTB及MDTBCTV均显著劣于俯卧位(P<0.001、P=0.001)。结论 与仰卧位相比,基于俯卧位构建EB-PBI靶区可显著减少不同勾画者间差异,提高勾画者间的一致性。因此,在自由呼吸状态下基于俯卧位施行EB-PBI更为合理。     

Localization of the surgical bed using supine magnetic resonance and computed tomography scan fusion for planification of breast interstitial brachytherapy

Purpose

To evaluate the feasibility of supine breast magnetic resonance imaging (MR) for definition and localization of the surgical bed (SB) after breast conservative surgery. To assess the inter-observer variability of surgical bed delineation on computed tomography (CT) and supine MR.

Materials and methods

Patients candidate for breast brachytherapy and no contra-indications for MR were eligible for this study. Patients were placed in supine position, with the ipsilateral arm above the head in an immobilization device. All patients underwent CT and MR in the same implant/treatment position. Four points were predefined for CT-MRI image fusion. The surgical cavity was drawn on CT then MRI, by three independent observers. Fusion and analysis of CT and MR images were performed using the ECLIPSE treatment planning software.

Results

From September 2005 to November 2008, 70 patients were included in this prospective study. For each patient, we were able to acquire axial T1 and T2 images of good quality. Using the predefined fusion points, the median error following the fusion was 2.7 mm. For each observer, volumes obtained on MR were, respectively, 30%, 38% and 40% smaller than those derived from CT images. A highly significant inter-observer variability in the delineation of the SB on CT was demonstrated (p < 0.0001). On the contrary, all three observers agreed on the volume of the SB drawn on MR.

Conclusion

Supine breast MRI yields a more precise definition of the SB with a smaller inter-observer variability than CT and may obviate the need for surgical clips. The volume of the SB is smaller with MRI. In our opinion, CT-MRI fusion should be used for SB delineation, in view of partial breast irradiation.     

磁共振弥散加权成像在食管癌大体肿瘤靶区勾画中的应用价值

目的 探讨磁共振弥散加权成像(DWMRI)在食管癌大体肿瘤体积(GTV)勾画中的应用价值。方法 29例行根治性食管癌切除术的食管鳞癌患者术前行常规CT、T₂WI下MRI及DWMRI (弥散敏感梯度b=400、600、800 s/mm²),分别在上述3种图像上勾画GTV。测量3种方法GTV长度并与术后标本上测量的病变长度比较,以确定最佳方法和条件,并计算该条件下外扩范围满足GTV照射要求的患者比例。利用放疗计划系统的图像融合功能将不同b值下DWMRI图像与CT图像融合,验证融合图像上勾画GTV的可行性。结果 CT和T₂WI下MRI图像上测量的GTV长度和标本上测量的病变长度差值分别为3.368 mm和2.84 mm;b=400、600、800 s/mm²时DWMRI图像上测量的GTV长度和标本上测量的病变长度差值分别为0.47、－0.47、－1.53 mm,其相关系数分别为0.928、0.927、0.938。DWMRI与CT图像在放疗计划系统中能很好融合,融合图像上食管癌病变两端分界清晰。结论 DWMRI能比较准确显示食管癌GTV长度和位置,利用放疗计划系统的图像融合功能可将DWMRI与CT图像进行融合并用于食管癌GTV勾画。     

Expanding the role of breast-conserving therapy using immediate volume replacement

Preventing local recurrence and preserving cosmetic appearance are often in conflict in breast-conserving therapy. Immediate volume replacement with autogenous tissue has been developed to allow a wider excision without compromising the aesthetic results. A review of the literature regarding immediate volume replacement in breast-conserving therapy has led to the following conclusions. When excision of the skin overlying the tumor is unnecessary, a transverse or lateral incision should be used which allows wide excision and immediate volume replacement with autogenous tissue while minimizing scar morbidity. The options for immediate volume replacement include the latissimus dorsi flap with adipose tissue, the latissimus dorsi myocutaneous flap, and the lateral thoracic adipose tissue flap. The choice of technique depends on the amount and position of the skin, subcutaneous tissue, and breast tissue which must be excised. These procedures can be used to extend the indications for breastconserving therapy, eliminating the need for mastectomy in selected patients. Future developments in the endoscopic harvesting of flaps may further expand the role of volume replacement.     

Effect of external boost volume in breast-conserving therapy on local control with long-term follow-up

PURPOSE: To determine the effects of boost volume (BV) in relation to margin status and tumor size on the development of local recurrence with breast-conserving therapy. METHODS AND MATERIALS: Between 1983 and 1995, 1,073 patients with invasive breast cancer underwent 1,101 breast-conserving therapies. Of these 1,101 BCTs, 967 were eligible for analysis. The BV was categorized into tertiles: <66 cm(3) (n = 330), 66-98 cm(3) (n = 326), and >98 cm(3) (n = 311). The median follow-up was 141 months. Separate analyses were done for women < or =40 years and >40 years. RESULTS: No significant difference in local recurrence was shown between the tertiles and the recurrence site. The 15-year local recurrence-free survival rate was 87.9% for the first tertile, 88.7% for the second, and 89% for the third. For women < or =40 years old, the corresponding 15-year local recurrence-free survival rate was 80%, 74.5%, and 69.2%. For women >40 years old, the corresponding rate was 88.7%, 89.5%, and 90.9%. At 5 years, women >40 years old had significantly more local failures in the first tertile; this difference disappeared with time. A test for trend showed significance at 5 years (p = 0.0105) for positive margins for ductal carcinoma in situ in women >40 years of age. CONCLUSION: The results of this study have shown that the size of the external BV has no major impact on local control. For women >40 years old, positive margins for ductal carcinoma in situ showed a trend with respect to BV at 5 years. The BV had no influence on local control in the case of positive margins for invasive carcinoma.     

The treatment outcome of patients undergoing breast-conserving therapy: the clinical role of postoperative radiotherapy

Background  Treatment outcome was evaluated in patients who underwent breast-conserving therapy and tangential irradiation. After verifying background factors including systemic therapy, the clinical efficacy of postoperative irradiation was investigated. Method  There were 708 study subjects, all of whom had early breast cancer treated between 1992 and 2002. The median follow-up period was 83 months. After breast-conserving surgery, in patients with negative surgical margins, only tangential irradiation at 48 Gy/24 fr was performed. In contrast, in those with positive surgical margins, 10 Gy of radiation boost to the tumor bed with electrons was administered after tangential irradiation with 50 Gy/25 fr. Treatment outcome was analyzed using the Kaplan–Meier method and Cox’s proportional hazards regression model. Results  The disease-free survival and no-recurrence rates within the ipsilateral breast after 5 years were 93.4 and 97.2%, respectively. Risk factors for recurrence within the ipsilateral breast included younger age of patient, the number of positive lymph nodes, and no endocrine therapy. However, the surgical margin was not a risk factor. Risk factors for relapse outwith the ipsilateral breast included younger age, the number of positive lymph nodes, and recurrence within the ipsilateral breast. Conclusions  From our analysis of 708 Japanese women who received breast-conserving therapy, which can be regarded as a standard method in Japan, the treatment outcome was compatible with previous reports from other countries. Presented in part at the 19th meeting of the Japanese Society for Therapeutic Radiation Oncology (JASTRO), 23–25 November 2006, Sendai, Japan.     

The impact of preoperative MRI on breast-conserving surgery of invasive cancer: a comparative cohort study

Aim To assess whether preoperative contrast-enhanced magnetic resonance imaging (MRI) of the breast influences the rate of incomplete tumor excision. Methods In a cohort of 349 women with invasive breast cancer, patients eligible for breast-conserving therapy (BCT) on the basis of conventional imaging and palpation only (N = 176) were compared to those who had an additional preoperative MRI (N = 173). Multivariate analysis was applied to explore associations with incomplete tumor excision. Results MRI detected larger extent of breast cancer in 19 women (11.0%), leading to treatment change: mastectomy (8.7%) or wider excision (2.3%). Tumor excision was incomplete in 22/159 (13.8%) wide local excisions in the MRI group and in 35/180 (19.4%) in the non-MRI group (P = 0.17). Stratified to tumor type, incompletely excised infiltrating ductal carcinoma (IDC) was significantly associated with absence of MRI: 11/136 (8.1%) versus 2/126 (1.6%) (MRI present) (P = 0.02). No significant factors explained incomplete excision of other tumor types. Conclusion Preoperative MRI did not significantly affect the overall rate of incomplete tumor excision, but it yielded significantly lower rate of incompletely excised IDC. The reduction of incomplete excisions after MRI was smaller than the rate of a prior treatment change incurred by MRI. J. L. Peterse was deceased.     

磁共振影像在乳腺癌放疗中的作用

近年来,随着磁共振定位和放疗设备的临床开发和应用,越来越多的研究开始关注磁共振的良好软组织分辨能力,力图探索磁共振影像在乳腺癌患者放疗中潜在的应用价值。本文就磁共振影像在乳腺癌保乳术后放疗中的研究进展进行综述,以期为未来研究提供一定思路和参考。     

Significance of irradiation in breast-conserving treatment: comparison of local recurrence rates in irradiated and nonirradiated groups

Breast-conserving treatment (BCT) is a standard therapy for early breast cancer. Many reports have described the effectiveness of post-BCT radiation therapy. However, the post-BCT local recurrence rate of only 5% to 10% indicates that radiation therapy may be unnecessary in many cases. To accurately select those patients who do not require post-BCT radiation therapy, we investigated the significance of irradiation in BCT by comparing local recurrence rates in irradiated and nonirradiated patients, grouped according to clinicopathological criteria that we evaluated. The patients were divided into two groups: a previous-criteria group and a present-criteria group. The former group included 85 patients in whom only two factors were considered as the criteria for radiation therapy: margin-positivity and lymphatic metastasis-positivity. The latter group included 318 patients in whom three additional factors were also considered: lymphatic invasion, intraductal extension, and metachronous/synchronous bilateral breast cancer. The use of five clinicopathological factors rather than two as the criteria for irradiation led to an increase in the irradiation ratio from 47.1% to 63.2% and a decrease in local recurrence from 12.9% to 2.2%. Because of the short average follow-up period of this study, further careful, regular follow-up and randomized comparative studies are required. It may also be necessary to include the patient age and margin condition as mandatory criteria for irradiation.     

The potential advantages of FDG PET/CT-based target volume delineation in radiotherapy planning of head and neck cancer

Purpose

This study investigated two fixed threshold methods to delineate the target volume using ¹⁸FDG PET/CT before and during a course of radical radiotherapy in locally advanced squamous cell carcinoma of the head and neck.

Materials and methods

Patients were enrolled into the study between March 2006 and May 2008. ¹⁸FDG PET/CT scans were carried out 72 h prior to the start of radiotherapy and then at 10, 44 and 66 Gy. Functional volumes were delineated according to the SUV Cut Off (SUVCO) (2.5, 3.0, 3.5, and 4.0 bwg/ml) and percentage of the SUVmax (30%, 35%, 40%, 45%, and 50%) thresholds. The background ¹⁸FDG uptake and the SUVmax within the volumes were also assessed.

Results

Primary and lymph node volumes for the eight patients significantly reduced with each increase in the delineation threshold (for example 2.5-3.0 bwg/ml SUVCO) compared to the baseline threshold at each imaging point. There was a significant reduction in the volume (p ? 0.0001-0.01) after 36 Gy compared to the 0 Gy by the SUVCO method. There was a negative correlation between the SUVmax within the primary and lymph node volumes and delivered radiation dose (p ? 0.0001-0.011) but no difference in the SUV within the background reference region. The volumes delineated by the PTSUVmax method increased with the increase in the delivered radiation dose after 36 Gy because the SUVmax within the region of interest used to define the edge of the volume was equal or less than the background ¹⁸FDG uptake and the software was unable to effectively differentiate between tumour and background uptake.

Conclusions

The changes in the target volumes delineated by the SUVCO method were less susceptible to background ¹⁸FDG uptake compared to those delineated by the PTSUVmax and may be more helpful in radiotherapy planning. The best method and threshold have still to be determined within institutions, both nationally and internationally.