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The New CT and MR DICOM Objects: Why All the Fuss?

The New CT and MR DICOM Objects: Why All the Fuss?. Brad Erickson David Clunie. Disclosures. Bradley J Erickson, MD PhD Member, Siemens Medical Advisory Board David Clunie, MBBS CTO, RadPharm (Princeton Radiology Pharmaceutical Research)

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The New CT and MR DICOM Objects: Why All the Fuss?

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  1. The New CT and MR DICOM Objects: Why All the Fuss? Brad Erickson David Clunie

  2. Disclosures • Bradley J Erickson, MD PhD • Member, Siemens Medical Advisory Board • David Clunie, MBBS • CTO, RadPharm (Princeton Radiology Pharmaceutical Research) • PixelMed Publishing - contractor for the NEMA Enhanced CT and MR test tools and images

  3. Acknowledgments • Kees Verduin, Philips Medical Systems • Robert Haworth, GE Healthcare • Charles Parisot, GE Healthcare • Bernhard Hassold, Siemens Medical Solutions

  4. A Brief History of DICOM • Early imaging devices created images in a vendor-proprietary format. Needed a common medical image format that would allow transfer of image data to workstations. That led to ACR-NEMA 1.0.

  5. DICOM Through the Decades • DICOM working groups have made significant improvements and extensions to the original specification. • Network protocols • Media • DICOM-SR • Hanging Protocols • CAD support

  6. But DICOM isn’t perfect

  7. But DICOM isn’t perfect • And even if it was, imaging changes…

  8. Problem: Important data elements are not standard • New pulse sequences have developed since DICOM (e.g. diffusion, perfusion, new CT scanning modes). I can’t process or display these well across vendor systems.

  9. Problem 1: Data Handling • We routinely acquire perfusion images on all patients with brain tumors. • If we archive the computed images, what happens if the software changes? • Therefore, we archive the raw data and computed images. But can new software ‘understand’ those older images to make valid comparisons?

  10. Problem 2: Hanging Protocols • My PACS uses the series # to determine where to hang a series. • This doesn’t reflect the complexity of my practice. (e.g. motion throws off #’s) • If all these new data fields are available, why can’t the workstation compute the image type (e.g. “T1 sagittal”, “T2 axial”) and hang it where I want it? (I want Post in the middle, and the Pre and T2 on either side)

  11. Organization of CT & MR Images • Original objects • Series organization + a few attributes + terms • Enhanced objects • Multiple frames in a single object • Many more standard mandatory attributes • Many more standard terms • Enables • Greater interoperability of applications • More effective hanging protocols • Reduced dependence on private attributes

  12. Technique Attributes & Terms

  13. CT Image Type Value 3 • Original SOP Classes • AXIAL or LOCALIZER • Enhanced SOP Classes • Common to CT and MR • ANGIO, FLUOROSCOPY, LOCALIZER, MOTION, PERFUSION, PRE_CONTRAST, POST_CONTRAST, REST, STRESS, VOLUME • CT-specific • ATTENUATION, CARDIAC, CARDIAC_GATED, REFERENCE

  14. MR Acquisition Contrast • Original SOP Classes • Guess from echo and repetition time, etc. • Enhanced SOP Classes • New mandatory frame level attribute • Acquisition Contrast • DIFFUSION, FLOW_ENCODED, FLUID_ATTENUATED, PERFUSION, PROTON_DENSITY, STIR, TAGGING, T1, T2, T2_STAR, TOF, UNKNOWN

  15. Geometry unchanged • Same as original SOP Classes • Image Position and Orientation (Patient) • Still need to compute AXIAL, SAGITTAL or CORONAL from orientation vector • Still need to compute edge labels (A/P etc) from orientation vector • May still need to compare orientation vectors to determine if slices are parallel - stacks will be discussed later

  16. Enhanced Contrast/Bolus • Original SOP Classes • Plain text description • Difficult to determine presence/absence • E.g., description value of “None” • Single agent (did not distinguish oral/iv) • Codes optional and never used • Enhanced SOP Classes • Mandatory codes only • Multiple items with separate coded routes & timing • Presence or absence per-frame can be described

  17. Coded anatomic regions • Original SOP Classes • Incomplete list of optional defined terms • Optional laterality • Enhanced SOP Classes • Mandatory coded anatomic region • Comprehensive & appropriate list of codes • Mandatory laterality • Per-frame or for entire object

  18. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD

  19. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1

  20. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1

  21. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1 Image Orientation ≈ 0\1\0\0\0\-1

  22. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1 Image Orientation ≈ 0\1\0\0\0\-1

  23. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1 Image Orientation ≈ 0\1\0\0\0\-1 Contrast Agent #1 Administered = NO Route = (G-D101,SNM3, “IV”) Ingredient = (C-17800,SRT, “Gd”)

  24. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1 Image Orientation ≈ 0\1\0\0\0\-1 Contrast Agent #1 Administered = NO Route = (G-D101,SNM3, “IV”) Ingredient = (C-17800,SRT, “Gd”)

  25. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1 Image Orientation ≈ 1\0\0\0\1\0 Contrast Agent #1 Administered = NO Route = (G-D101,SNM3, “IV”) Ingredient = (C-17800,SRT, “Gd”)

  26. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1 Image Orientation ≈ 1\0\0\0\1\0 Contrast Agent #1 Administered = NO Route = (G-D101,SNM3, “IV”) Ingredient = (C-17800,SRT, “Gd”)

  27. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1 Image Orientation ≈ 1\0\0\0\1\0 Contrast Agent #1 Administered = NO Route = (G-D101,SNM3, “IV”) Ingredient = (C-17800,SRT, “Gd”)

  28. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T2 Image Orientation ≈ 1\0\0\0\1\0

  29. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T2 Image Orientation ≈ 1\0\0\0\1\0

  30. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T2 Image Orientation ≈ 1\0\0\0\1\0

  31. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1 Image Orientation ≈ 1\0\0\0\1\0 Contrast Agent #1 Administered = YES Route = (G-D101,SNM3, “IV”) Ingredient = (C-17800,SRT, “Gd”)

  32. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD Acquisition Contrast = T1 Image Orientation ≈ 1\0\0\0\1\0 Contrast Agent #1 Administered = YES Route = (G-D101,SNM3, “IV”) Ingredient = (C-17800,SRT, “Gd”)

  33. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD

  34. Hanging protocol rule impact T1 SAGPRE GD T2 AXIAL T1 AXIALPRE GD T1 AXIALPOST GD • Same rules, independent of whether: • one single multi-frame image • one multi-frame image per acquisition • one slice per single frame image • one series or multiple

  35. Hanging protocol support • A productivity advantage of the CT and MR objects • Should not have to tailor hanging protocol rules to specific vendors or devices or versions • Reliable and standard information • Mandatory and standard places (attributes) • Mandatory and standard values • As technology evolves, yet more standard values will be added to the standard • Eliminate dependence on site configured Series Number or Description, whether from acquisition protocol or entered by operator

  36. DICOM Hanging Protocols • Foregoing describes how to use attributes in Enhanced CT and MR objects to improve any hanging protocol engine, including proprietary software • DICOM also has recently defined Hanging Protocol SOP Classes • To store hanging protocol rules centrally and exchange them between different systems • Not a pre-requisite for making use of the enhanced image objects to improve hanging

  37. More Hanging Protocol Problems • We often do multi-phase CT exams. The hanging protocol should “automagically” hang the pre-contrast, arterial phase, venous phase, late phase in separate stacks.

  38. Lung Nodule Protocol: Pre + 1 scan every minute post-Contrast Vendor X Vendor Y *Courtesy B Bartholmai

  39. Multi-phase Liver CT Current—Vendor X—all post-contrast in 1 series

  40. What I want: separate, linked stacks

  41. Hanging Protocols • We have routine scanning protocols. For these, I don’t want to see the parameters. But for cases where the tech had to do something non-standard, (e.g. flip from prone to supine) I want that to stand out.

  42. Jane Doe 19 May 05 1-345-989 16:32:12 R Supine

  43. Problem: 3D • We want to fuse PET images with CT and MR images (from different vendors). • We also want to record the alignment solution for future use.

  44. Beyond simple image display • Visualization • Temporal change • Short term • Long term • Quantitation and Analysis

  45. Visualization • MPR • 3D surface and volume rendering • MIP for angiography

  46. Temporal change • Short term • Perfusion • Cardiac cycle • Long term • Change between studies

  47. Quantitation and analysis • Processing of multiple frames • Measurement of morphology • Linear distance • Volumetrics • Measurement of physiology and function • Perfusion and diffusion • fMRI • Registration • between acquisitions, studies & modalities

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