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  • Lung Image Database Consortium

LIDC Radiologist Instructions for Spatial Location and Extent Estimates

  1. Viewing Conditions
    1. Ambient light
      1. Room lighting dimmed to simulate clinical reading environment
    2. Monitor
      1. Monitor calibrated
      2. Monitor specifications of clinically acceptable caliber
  2. Case Nomination
    1. Scan inclusion criteria
      1. Screening or diagnostic examination; limited-anatomy diagnostic examination
      2. Reconstruction interval and collimation both < 3 mm
      3. Scans may include high levels of noise or streak, motion, or metal artifacts
      4. Other pathology may be present, unless it is spatially contiguous with nodules and substantially interferes with their visual interpretation
    2. Nodule inclusion criteria
      1. The term “nodule” represents a spectrum of parenchymal abnormalities (irrespective of presumed histology), which is itself a subset of a broader spectrum of abnormalities termed “focal abnormality;” a lesion should be considered a “nodule” if it satisfies the definition of “nodule” (the most essential component of which is its "nodular" morphology within the lung parenchyma)
      2. Number of nodules with longest diameter between 3-30 mm should not exceed 6 (at least on the initially contributed scan of any particular patient)
      3. Nodules may represent primary lung cancers, metastatic disease, or non-cancerous processes; since a decision on whether a lesion is a “nodule” should not be made based on presumed histology, the presence of calcifications should not be a factor in determining the “nodule” status of a lesion
  3. Blinded Read
    1. Categories
      1. Nodules > 3mm diameter (full contour, see below)
      2. Nodules < 3mm diameter (centroid only, see below)
      3. Non-Nodules > 3mm  diameter (centroid only, see below)
    2. Sizing
      1. Use electronic calipers to estimate lesion’s longest diameter in the section demonstrating greatest extent of lesion
      2. Lesion’s axial extent should not be considered in lesion sizing
    3. 3 mm < Nodule < 30 mm
      1. Draw outline around the nodule in all sections in which it appears, with the pixels that comprise the outline at the first pixel outside the nodule
      2. “Regions of exclusion” within the nodule may be eliminated through construction of another outline, again with the pixels that comprise the exclusion outline considered part of the region of exclusion
    4. Nodule < 3 mm
      1. Indicate approximate three-dimensional center-of-mass of any such nodule of indeterminate nature
      2. If the opacity is clearly benign, no marking
    5. Non-nodule > 3 mm
      1. Indicate approximate three-dimensional center-of-mass
      2. Indicate a “non-nodule nexus” region with a mark at its approximate three-dimensional center-of-mass or at a prominent focus of the nexus (note that the database will make no distinction between the single mark assigned to a “non-nodule nexus” and the single mark assigned to a single lesion considered a “non-nodule > 3 mm”); nodules within a non-nodule nexus may be indicated separately in accordance with III.c. and III.d.
      3. A mass that exceeds 30 mm should be marked as a “non-nodule > 3 mm”
    6. Non-nodule < 3 mm
      1. No marking
    7. Non-lesion
      1. No marking
  4.            Unblinded Read
    1. Lesion matching
      1. Software will “group” outlines from multiple radiologists that correspond to the same physical structure within the scan
      2. Centroid positions may or may not be “grouped” by the software, depending on the software being used
    2. Lesion review (all elements of Section III pertain to Unblinded Reads)
      1. Review markings of all radiologists for all lesions
      2. For a lesion with at least one blinded read outline:
        1. identify your blinded assessment of this lesion (if you provided one)
        2. if you outlined this lesion, review your outlines on all sections in the context of the outlines constructed by the other radiologists (if any) or you may reclassify your assessment of this lesion to a centroid-only marking or to no markings
          1. modify your outlines, if necessary, by:
            1. editing your outline in a specific section or sections,
            2. creating an additional outline in a section you did not previously include, and/or
            3. deleting an outline from a section you previously included (you may not simply accept the outlines of another)
          2. otherwise, accept your blinded outline without modification (maintain your blinded outline unless the outlines of other radiologists provide strong evidence for modification)
        3. if you marked only a centroid for this lesion, you may:
          1. maintain (or spatially adjust) your centroid marking,
          2. reclassify your assessment of this lesion to “nodule > 3 mm” and outline it, or
          3. reclassify your assessment of this lesion to no markings
        4. if you did not mark this lesion at all, you may:
          1. maintain your assessment,
          2. reclassify your assessment and place an approximate three-dimensional centroid, or
          3. reclassify your assessment to “nodule > 3 mm” and outline it
      3. For a lesion with no blinded read outlines, but at least one centroid marking:
        1. identify your blinded assessment of this lesion
        2. if you marked a centroid for this lesion, you may:
          1. maintain (or spatially adjust) your centroid marking,
          2. reclassify your assessment of this lesion to “no markings,”
          3. or reclassify your assessment of this lesion to “nodule > 3 mm” and outline it
        3. if you did not mark a centroid for this lesion, you may:
          1. maintain your assessment of this lesion,
          2. reclassify your assessment and place an approximate three-dimensional centroid (or accept the existing centroid of another radiologist), or
          3. reclassify your assessment to “nodule > 3 mm” and outline it
      4. Newly identified lesions with no blinded markings may be assessed according to Section III
    3. Non-nodules
      1. Any blinded read “non-nodule > 3 mm” marking located within a pre-defined distance from a blinded read “nodule < 3 mm” centroid or a blinded read “nodule > 3 mm” outline (regardless of which radiologist provided the “nodule” or “non-nodule” marking) is to be reviewed as described above
      2. All other blinded read “non-nodule > 3 mm” markings will appear in a worklist but need not be explicitly reviewed by any radiologist
        1. by default, these other “non-nodule > 3 mm” marks placed by a radiologist will be included, without modification, in that radiologist’s own unblinded read response but will not appear in the unblinded read response of any other radiologist
        2. a radiologist may review any of these other “non-nodule > 3 mm” marks to “accept” another radiologist’s marks or to “reject” their own marks (or to make any of the reclassifications described above)
      3. The “non-nodule > 3 mm” mark should not be used solely to counter a blinded-read “nodule < 3 mm” or “nodule > 3 mm” mark.   The “non-nodule > 3 mm” mark conveys a reader's opinion that (1) a structure is an abnormality (but not a nodule) and (2) the structure exceeds 3 mm in longest dimension.  If a structure does not meet these two criteria and if the reader does not think the structure is a nodule, then not assigning any mark properly indicates that a reader did not think that any of the three categories were appropriate.
    4. Lesion ratings
      1. For nodules > 3 mm that you have identified after the unblinded read, rate likelihood of malignancy based on the assumption of a 60-year-old male smoker (since clinical information is not provided)