Module 7 Dr Margolis-Mri&Imaging


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Module 7 Dr Margolis-Mri&Imaging

  1. 1. DavidDavidGeffenGeffenSchool ofSchool ofMedicineMedicine Imaging for Prostate Cancer Daniel J A Margolis, MD Co-Director, Prostate MRI Assistant Professor of Radiology UCLA Geffen School of Medicine
  2. 2. Imaging For Prostate Cancer:David BackgroundGeffenSchool of  A 2011 Harvard study found that aMedicine quarter of men with low risk cancer received scans they did not “need”  A number of high-risk men do not get the scans needed to plan treatment  Newer modalities such as MRI and PET are not widely used
  3. 3. Imaging for Prostate Cancer:David ConsiderationsGeffenSchool of  Whether a man needs imaging, andMedicine what kind, is based on risk  PSA  Number and % of positive biopsies and  Grade of cancer on biopsy  Age and overall health  Imaging for staging benefits high risk more than low risk  Imaging can also be used to localize cancer within (& around) the prostate
  4. 4. Imaging TypesDavidGeffenSchool of  Prostate and surrounding tissueMedicine  Color power Doppler ultrasound (PDUS)  Magnetic resonance imaging (MRI)  Shear wave ultrasound elastography  Bones and lymph nodes  Computed tomography (CT)  Radionuclide (planar) bone scan (RBS)  Positron emission tomography (PET)  MRI
  5. 5. UltrasoundDavidGeffenSchool of  Courtesy Duke BahnMedicine
  6. 6. UltrasoundDavidGeffenSchool of  Regular gray-scale ultrasound canMedicine identify cancer, but cannot discriminate it from benign changes  Because of the abnormal blood supply, a Doppler signal shift is seen with prostate cancer on PDUS  However, whether this results in increased detection varies by institution  Ultrasound IV contrast dye increases yield, but is not approved in the USA
  7. 7. Ultrasound ElastographyDavidGeffenSchool of From theMedicine American Journal of Roentgen- ology
  8. 8. Ultrasound ElastographyDavidGeffenSchool of  Elastography is the measurement ofMedicine the stiffness of tissue  Cancers are stiffer than normal tissue  New elastographic techniques measure the shear wave tissue properties of ultrasound using Young’s modulus  Biopsy detection yield improves  This may identify men who do not need biopsies, but this is unknown
  9. 9. Prostate MRI: Why?DavidGeffenSchool of  The decision to remove the prostateMedicine surgically vs. radio/chemotherapy is based primarily on clinical factors  PSA  Biopsy  Physical Examination  These factors cannot reliably tell if the cancer has spread beyond the prostate, nor on which side  Systematic biopsies can and often do miss the most aggressive tumors
  10. 10. Background: Prostate CancerDavid Statistics– ScreeningGeffenSchool ofMedicine  Breast cancer has the mammogram  Colon cancer has colonoscopy  Courtesy
  11. 11. Prostate MRIDavidGeffenSchool ofMedicine Anatomy Chemical concentrations Cellular density Blood flow
  12. 12. What is MRIDavidGeffenSchool of  Magnetic Resonance Imaging usesMedicine magnetic pulses to generate images of tissue in the body  Images can be based on inherent magnetic properties of tissue to delineate anatomy or on functional parameters  Blood flow  Cellular packing and disorder  Concentrations of chemicals
  13. 13. Components of MRIDavidGeffenSchool of  T2-weighted imaging for anatomyMedicine  Diffusion-weighted imaging to evaluate cellular packing and disorder  Perfusion (dynamic contrast) imaging for blood flow  Spectroscopic imaging to measure levels of chemicals involved in normal prostate function and cancer
  14. 14. For what does prostate MRI look?DavidGeffenSchool of  Location and amount (and possiblyMedicine aggressiveness) of cancer in the prostate  Spread of prostate cancer  Seminal vesicles and neurovascular bundle (nerves that run along prostate)  Lymph nodes  Bones
  15. 15. Prostate MRI–David the Holy Grail of Prostate Imaging?GeffenSchool of  Prostate MRI involves lying motionlessMedicine on a table for about an hour  The only needles involved are an IV and an injection of a drug for cramps  Resolution and contrast are superior to ultrasound and CT scanning  Completely safe except in rare cases  Pacemaker  Claustrophobia  Kidney failure
  16. 16. Prostate MRI–David Anatomical CharacterizationGeffenSchool of  Conventional MRI techniques,Medicine combined with the optimized signal- to-noise ratio achieved with the endorectal coil, provides high resolution images of the prostate  These images are used to look at the area around the prostate for invasion of the capsule and seminal vesicles
  17. 17. Criteria for Prostate Cancer on T2WIDavidGeffen  Cancer appears darkSchool ofMedicine (red arrow) against the bright normal gland  Extension to seminal vesicles (gold arrow) indicates invasion  Obliteration of the rectoprostatic angle (preserved, green arrow) would indicate extracapsular extension
  18. 18. Signs of Extracapsular ExtensionDavidGeffenSchool of  Gross extension beyond theMedicine expected prostatic capsule is invasion outside the prostate  Other signs suggest capsular involvement or microscopic extension  Broad base of contact  Bulging  Blurring or irregularity  The small dots at the rectoprostatic angle may represent the nerve bundle
  19. 19. MRI Spectroscopy:David Chemical CharacterizationGeffen  MRI can determine theSchool ofMedicine concentration of some chemicals, although the resolution is less than anatomic imaging Abnormal High Normal  Choline is a marker of choline High peak cellular proliferation citrate peak and is increased in cancer Abnormal  Citrate is a normal low citrate constituent of healthy peak Normal prostate cells low  “Spectra,” or line choline peak graphs, show the concentration of these chemicals
  20. 20. MRI Spectroscopy:David Chemical CharacterizationGeffenSchool ofMedicine  Anatomic image showing bilateral PZ dark areas  Spectra from the patient’s right shows abnormal spectra consistent with cancer  Spectra from the left shows normal spectra most likely consistent with old inflammation
  21. 21. Diffusion-Weighted MRI:David Cellular DensityGeffenSchool of  Prostate cancer cells are more denselyMedicine packed than healthy cells  This restricts free water motion in the cells  MRI can detect motion in addition to chemicals  MRI generates a map of free water motion (“Brownian motion”) to localize densely packed cells in areas of old inflammation which are already dark
  22. 22. Diffusion-WeightedDavid MRI: Cellular DensityGeffenSchool of  The peripheral zoneMedicine on the upper image is uniformly dark, likely from old inflammation  The diffusion map localizes cancer to the patient’s right side
  23. 23. MRI Perfusion Imaging:David Blood Flow DynamicsGeffenSchool of  Cancer requires a rich blood supplyMedicine  Tumors secrete chemicals that grow new blood vessels  MRI can track contrast dye and identify areas of abnormal blood flow  Fast imaging can generate snapshots  Complex computer models can then generate parameters of blood flow
  24. 24. MRI PerfusionDavid ImagingGeffen  A dark area isSchool ofMedicine known proven cancer  This same area has impaired diffusion = densely packed cells  Abnormal perfusion map signifies new blood vessels
  25. 25. Prostate MRI: Holy Grail or YetDavid Another Drain on Health Care?GeffenSchool of  Again, not a straightforward answerMedicine  Prostate MRI is probably neither, but has specific uses:  Guiding biopsies  Surveillance  Presurgical staging for moderate-risk disease and minimally-invasive therapy  Follow-up
  26. 26. Prostate MRI: Biopsy GuidanceDavidGeffenSchool of  In the face of a rising PSA andMedicine negative biopsy, a “second look” is warranted  MRI can pinpoint the most suspicious area in the prostate  Biopsy can be done directly with MRI or with ultrasound/MRI image fusion under ultrasound guidance
  27. 27. Biopsies: MRI, Ultrasound, or NoneDavid At All!?GeffenSchool of  Currently, MRI has not been proven toMedicine exclude significant cancer  Whether this is true is being investigated  Most ultrasound biopsies are systematic, not based on imaging findings  MRI-guided biopsies can target suspicious areas directly with confirmation  But MRI machines cost as much as 10x as an ultrasound machine
  28. 28. Biopsies: MRI, Ultrasound, or Both!?DavidGeffenSchool of  New technology can fuse MRI dataMedicine with ultrasound  Suspicious findings from MRI can be co- localized on ultrasound and biopsied  This can expand image-guided biopsies to patients where MRI biopsies are unavailable
  29. 29. Prostate MRI: Active SurveillanceDavidGeffenSchool of  In patients with low volume, low gradeMedicine disease, MRI provides two advantages  Screen for missed areas suspicious for high-grade cancer  Baseline imaging for follow-up, to look for subtle changes
  30. 30. Prostate MRI: Therapy PlanningDavidGeffenSchool of  MRI provides two pieces ofMedicine information which are useful when planning surgical or radiation therapy  Overall size and location of the prostate and cancer within it  Spread of tumor beyond the prostate, especially into sensitive nerve bundles or the bladder or rectum  MRI can also detect spread to the lymph nodes or bones in the pelvis
  31. 31. Prostate MRI: Follow-Up Rising PSADavidGeffenSchool of  A rising PSA level after prostatectomyMedicine suggests recurrence of cancer  MRI has been shown to be sensitive to detect recurrent cancer  Surgical bed  Bones  Lymph nodes  MRI can also detect recurrence in the radiation therapy field
  32. 32. The Dreaded Coil – Is It Necessary?DavidGeffenSchool ofMedicine  The endorectal coil improves image quality about 10-fold  It is only necessary to characterize the prostate capsule for invasion near the neurovascular bundle  It improves quality of spectroscopy  Not needed for cancer detection  For example, biopsy planning
  33. 33. Staging for Bones and Lymph NodesDavidGeffenSchool of  The use of CT and bone scans forMedicine prostate cancer staging primarily benefits intermediate to high risk men  Guidelines were established over a decade ago and remain largely unchanged From a 2007 article by H Hricak in the journal Radiology
  34. 34. CT ScansDavidGeffenSchool ofMedicine
  35. 35. CT Scans for StagingDavidGeffenSchool of  Computed Tomography is a 3D X-rayMedicine  It is sensitive for enlarged lymph nodes and bony abnormalities  It is not sensitive for spread of cancer to small lymph nodes  Some bone lesions are nonspecific on CT – they could be cancer or benign  IV and oral contrast improves detection of lymph nodes  It does not characterize the prostate
  36. 36. Why Get a CT Scan?DavidGeffenSchool of  Treatment planningMedicine  e.g. external beam radiation therapy  Treatment monitoring  But PSA monitoring is cheaper  Confirm no obvious disease outside of pelvis  Confirm bone scan findings
  37. 37. Radionuclide Bone ScanDavidGeffenSchool ofMedicine
  38. 38. Radionuclide Bone ScanDavidGeffenSchool of  99Tc-MDP is a radioactive compoundMedicine taken up in areas of bone turnover  Reflects the body’s response to cancer, not the cancer itself  Some other tumors are not “hot” on RBS  Only detects bone metastases  False positives in benign diseases, e.g. arthritis, can be identified on X-ray  Fast, complete survey of skeleton
  39. 39. Why Get a Bone Scan?DavidGeffenSchool of  Treatment planning, e.g.Medicine  External beam radiation therapy  Samarium-153-EDTMP or Strontium-89  Treatment monitoring  But PSA monitoring is cheaper  Confirm no bone disease outside of pelvis  Characterize pain
  40. 40. Positron Emission TomographyDavidGeffenSchool ofMedicine
  41. 41. PET for Prostate CancerDavidGeffenSchool of  Conventional PET scanning can oftenMedicine detect spread of higher-grade disease  However, current PET agents are less good for prostate than other cancers  Experimental agents which show promise have not been shown useful in larger studies  Bone scans with 18Fluoride are also promising
  42. 42. PET Scans With More SpecificDavid AgentsGeffenSchool of  Conventional PET scans use an analogMedicine of glucose (sugar) to highlight the increased metabolism of cancer  Prostate cancer has cell surface receptors for testosterone  Researchers at Sloan-Kettering at Cornell devised a PET agent which mimics testosterone
  43. 43. PET Scans With Testosterone-David Specific AgentGeffenSchool of  Comparison of testosterone (A) andMedicine glucose (B) labeling on PET  Some tumors are equally well seen  Others are more obvious on the testosterone scan
  44. 44. PET Scans With Choline and FluroideDavidGeffenSchool ofMedicine  As seen on MRI, choline is increased in prostate cancer  A PET compound, 18Fluorocholine, is concentrated in high cellular turnover  18Fluoride is taken up in most bone lesions  CT on right, PET on left  18 FCholine on top, 18F below  White arrow: benign  Black arrows: cancer
  45. 45. Magnetic Resonance Imaging ReduxDavidGeffenSchool ofMedicine
  46. 46. MRI for Lymph Nodes and BonesDavidGeffenSchool of  MRI has superior sensitivity to CT forMedicine bone metastases but only slightly  Can still be confused by benign changes  MRI is equally sensitive to CT for lymph nodes  Costs more and takes longer to scan  Still relies on lymph node enlargement  A MRI contrast agent to detect micro- metastases to lymph nodes was not approved, but a new one is under review
  47. 47. MRI Lymph Node ImagingDavidGeffenSchool ofMedicine  Benign lymph node  Lymph node with malignant infiltration  Partial infiltration Courtesy M Harisinghani, Mass. Gen. Hospital
  48. 48. Take Home PointsDavidGeffenSchool of  Medicine has many options forMedicine imaging prostate cancer  Which one depends on the overall risk level and planned treatment  Some modalities are better for evaluating the prostate itself  Others are useful for whole body staging
  49. 49. DavidDavidGeffenGeffenSchool ofSchool ofMedicineMedicine Thank You For Your Attention Questions?