Imaging Tissue Response to Therapeutic Radiation

Transcription

1 1 Imaging Tissue Response to Therapeutic Radiation Sean P. Frigo, Ph.D. Assistant Professor Department of Human Oncology School of Medicine and Public Health University of Wisconsin Madison

2 Slide 1 1 Based on talk presented at WIMP Sean Frigo, 9/10/2015

3 RSNA NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 2

4 OK, let s jump in NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 3

5 A beautiful treatment plan doesn t tell us enough No dose: No effect High dose: Lot s of effect Intermediate dose:??? effect NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 4

6 How do you define response? What metrics to use? What action levels for these metrics? Establishing correlation Establishing causation Observation Target: It goes away Non-target: It keeps working (good), or begins to malfunction (bad) NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 5

7 How do you define response? Each patient is different Wouldn t we want to know if the current patient being planned could actually tolerate 60 or 70 Gy to their spinal cord? How can we measure that? NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 6

8 Population to person Where does a patient lie on the curve? Amifostine NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 7

9 Functional mapping Organ status and function over time From To Physical Dose Indicator or Metric Surrogate for the potential for response Indicating whether function is getting better or worse NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 8

10 Measuring response to treatment Current options are pretty limited Short-term Toxicity Physical exam and interview Long-term RTOG trial Survival NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 9

11 Measuring response Seeing more better and sooner CT Perfusion Large volume, high spatial and temporal resolution, elemental specificity MR High spatial and temporal resolution, molecular specificity Spectroscopy NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 10

12 Measuring response Different levels of analysis... Spatial Longest length Volume Morphology (surface texture) Heterogeneity (density analysis) Wavelets Functional FDG updake O 2 presence (hypoxia) Blood flow (perfusion) Composition MR spectroscopy NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 11

13 RECIST Response Evaluation Criteria In Solid Tumors A set of rules that define when tumors improve ("respond"), stay the same ("stabilize"), or worsen ("progress") during treatment The approach is tumor-centric, not patient centric. Measurable lesions are lesions that can be accurately measured in at least one dimension. The goal of these measurements is to provide a quantitative assessment of whether the tumor is changing size. CT and MRI are the best currently available and reproducible methods to measure target lesions selected for response assessment NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 12

14 RECIST Tools Manual: Ruler to identify distance Automatic: Segmentation NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 13

15 RECIST Limitations 1. Longest axis does not necessarily represent tumor volume. 2. Malformed tumors make selecting a longest axis challenging. 3. A tumor may stay the same size, but in fact have necrosis in the tumor interior. 4. Tumor orientation relative to the imaging device can introduce error. 5. Operator error can be introduced by computer screen size. 6. A subset of tumors may not accurately represent a patient having dozens of tumors NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 14

16 RECIST Improvements and extensions These would help: RECIST D Volume assessment 2. 3D shape assessment 3. Intensity profile assessment PERCIST Density and mass assessment 5. Include all tumors NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 15

17 If tissue could talk NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 16

18 A ph scale for response? Negative values for non-disease tissue, where more negative means greater impact Positive values for disease tissue, where more positive means greater impact Zero: No Impact NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 17

19 Liver metastasis study Cyberknife SBRT treatment RECIST-based lesion tracking Supplemental criteria NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 18

20 CT imaging example Complete response NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 19

21 CT imaging example Progressive lesion NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 20

22 PET study Correlating PET uptake to survival NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 21

23 PET study Correlating PET uptake to survival Conclusion A large decrease in 18 F-FDG uptake early during treatment correlates with improved overall survival NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 22

24 Measuring response Some progress in MR NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 23

25 Measuring response Some progress in MR NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 24

26 Functionally adaptive patient care A vision Image Measure current target and sparing status Patient Assess Is function in line with expectation? Modify Adjust dose to bring function in line with goals NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 25

27 Thanks to Ed Jackson Robert Jeraj Clemens Grassberger NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 26

28 NCAAPM Fall Imaging Tissue Response to Therapeutic Radiation 27