功能影像学技术在头颈部肿瘤放疗计划制定、疗效评估和个体化治疗中的应用课件

1、Functional Imaging for Radiation Treatment Planning, Response Assessment, and Adaptive Therapy in Head and Neck Cancer福建省肿瘤医院郑德春 博士Role of routine and functional Imaging (FI)Screening and diagnosis of neoplasmsPrecise staging of malignancyResponse assessment of cancer treatmentMonitor recurrencesBen

2、efit of FIMajor modalities of FI:positron emission tomography (PET) combined with CT or magnetic resonance (MR) imagingfMRI: DWI, DCE-MRI, BOLD, spectroscopy etc.Emerging techniques: PET-MRI, DKI, IVIM, APT, CEST etc.Offer complementary information including metabolism of FDG, proliferation, hypoxia

3、, and cell membrane synthesis by PEThypoxia and permeability by DCE MRI and IVIM, cell proliferation and apoptosis by DWI, IVIM and DKI, and epidermal growth factor receptor status.About this articlePart I: Discusses the practical aspects of integrating functional imaging into head-and-neck radiatio

4、n therapy planning. Part II: Reviews the potential of molecular imaging biomarkers for response assessment and therapy adaptation. Authors concluded that FI allowed more individualized treatment planning in patients with head and neck SCCs in the emerging era of personalized medicine.Part I Role of

5、Functional Imaging in Radiation Therapy PlanningThere was a 20% decrease in OS among patients who underwent radiation therapy with a protocol that did not comply with established institutional standards. Reasons: Inaccuracies in tumor target delineation Inter-observer variability in clinical practic

6、e based on CT for target delineationFunctional MRI and PET techniques provide different and potentially complementary information about the tumor extent and biologic activity.Example of automated delineationFigure 2. SCC arising from the epiglottis (T2N2bM0) in a 67-year-old man. Axial fused FDG PET

7、/CT image shows tumor contours automatically generated with diagnostic software by using percentages of the maximum SUV (20%, 30%, 40%, and 50%) and a fixed SUV cutoff of 2.5.Automated delineation is believe to be more objective than visual delineation. Because, an alteration of the SUV scale can ch

8、ange the apparent tumor volume and lead to increased inter-observer variability.Status of PET-contouring at presentAt present, there is no consensus regarding the optimal contouring method.The most practical approach to defining the tumor target is to rely on expert visual interpretations by nuclear

9、 medicine physicians and radiologists And rely on knowledge of the likely patterns of disease infiltration within strict SUV scale limits. However, limited spatial resolution and partial volume effects blur the edges of FDG-avid tumors at PET. PET-based Radiation Therapy PlanningDuprez et al (24) de

10、monstrated the feasibility of applying dose escalation to an FDG PETavid GTV with dose painting by numbers instead of with GTV contouring.The use of multimodality imaging raises the question of whether the GTV should be defined on the basis of imaging with only one or with several modalities？ The la

11、ck of concordance found between various imaging modalities suggests that the safest approach when defining a target is to use all imaging modalities along with physical examination. Anatomic and functional imaging modalities could provide different but complementary information during contouring and

12、 planning for cancer RT treatment.Contour lines are color coded to show the imaging modality on which they are based (green = CT, blue = MR imaging, orange = PET).Adaptive Radiation Therapy PlanningThere is considerable interest in personalizing treatment in an attempt to optimize the therapeutic ra

13、tio for individual patients. One avenue for achieving this is to alter the delivery of radiation therapy on the basis of changes in the tumor and/or normal organs during a course of treatment.Mainly current radiation therapy is planned at a single pretreatment time-point to delineate the target volu

14、me and any organs at risk, with no account taken of anatomic changes during the course of fractionated radiation therapy. Adaptive Radiation Therapy PlanningIt provides an opportunity to improve the therapeutic ratio by minimizing the overall dose to organs at risk and escalating the dose to areas o

15、f tumor tissue. 18F-fluorothymidine (FLT) PET/CT is a noninvasive method for monitoring proliferation during treatment. Troost et al showed that decreases in tumor-related FLT uptake occurred early after the administration of the fifth radiation dose fraction. By contrast, changes in the CT-defined

16、GTV were detectable only after 4 weeks of radiation therapy. These data demonstrated the feasibility of escalating the radiation dose administered to tumor sub-volumes with high proliferative activity in the 2nd week of treatment.Figure 6. Adaptive therapy planning in a 68-year-old man with a suprag

17、lottic SCC (T2N2bM0) treated with chemoradiation therapy. (a) Axial fused PET/CT image obtained before the start of therapy shows marked metabolic activity (SUVmax, 22.2) in the tumor (arrowhead). (b) Axial fused PET/CT image obtained after 11 fractions of radiation therapy shows a reduction in tumo

18、r size and metabolic activity (SUVmax, 9.7). (c) Axial fused PET/CT image, obtained after 21 fractions of radiation therapy, shows continued reduction in tumor size and metabolic activity (SUVmax, 7.9).Mainly issues of FI to guide A-RT planning1、 the choice of imaging modality. 2 、imaging characteri

19、stics may not be reproducible at successive imaging evaluations. 3、 the optimal timing of imaging assessments during the course of treatment is unknown.4 、the optimal method for defining tumor contours is unclear. PART II Functional Imaging for Disease Response Assessmentfunctional imaging appears t

20、o be a promising addition to clinical examination and anatomic imaging for assessing the response of head and neck SCC tumors to radiation therapy. This is particularly true in the clinical scenario of residual masses, where anatomic imaging techniques are inaccurate. The use of FDG PET is now suppo

21、rted by considerable data. A role also may be established for other PET- and MR imagingbased techniques.I selected fMRI as my favorite lecture today. While leave PET for colleague from nuclear medicine department.Functional MR Imaging TechniquesAdvanced MR imaging techniques such as dynamic contrast

22、-enhanced imaging, diffusion-weighted imagingblood oxygenation leveldependent (BOLD) imagingspectroscopy hold the promise of providing functional information about disease. These techniques can be used for planning, monitoring, and assessing the results of radiation therapy in patients with head and

23、 neck SCCs.Dynamic Contrast-enhanced Imagingit is a noninvasive technique that helps characterize the microvasculature, thereby providing markers specific to perfusion, permeability of blood vessels, and the volume of extracellular space. Abnormal microvessels seen at dynamic contrast-enhanced MR im

24、aging themselves may be a marker of hypoxiaTumor angiogenesis is associated with chaotic vessel formation and incompetent arteriovenous shunts, which lead to less effective perfusion and a more hypoxic environment than exists in normal tissues.Previous studies of DCE MRINewbold et al demonstrated a

25、statistically significant correlation between various DCE-MRI parameters, particularly Ktrans (which represents the permeability of blood vessels) and pimonidazole staining (an exogenous marker for hypoxia). The appearance of head and neck SCCs at dynamic contrast-enhanced MR imaging also has been u

26、sed to successfully predict treatment response to chemoradiation therapy in the tumors (85). (a) Axial T1-weighted MR image obtained for planning of chemoradiation therapy in a 62-year-old man shows a primary SCC in the left aspect of the tongue base (T4N2bM0) (arrow) and a nodal metastasis (arrowhe

27、ad). (b, c) Axial dynamic contrast-enhanced MR images before and after RT showincreased vascular permeability (Ktrans) before radiation therapy in the primary tumor (arrow in b) and cervical node (arrowhead in b) decreased permeability after 11 fractionated doses of radiation therapy in the tumor (a

28、rrow in c) and node (arrowhead in c). These findings are indicative of therapeutic response.Studies have shown that DWI can be useful for differentiating small malignant lymph nodes from nonmalignant ones In one study, a sensitivity of 76% was obtained with the use of ADC at diffusion-weighted imaging for detecting subcentimetric lymph node metastases, in comparison with a sensitivity of 7% obtained with the use of morphologic features and size depicted at conventional MR imaging In another study, in 33 patients with head and neck