1. There are 4 software programs that will be discussed.
   1. AutoQUANT and Cedars blood-pool gated SPECT (BPGS)
   2. 4D-MSPECT
   3. Emory Cardiac Tool box (ETB)
   4. Baylor polar map package (currently not available)

2. Following cardiac acquisition auto orientation must occur to reconstruct the LV from its angular position to parallel transverse images
   1. Myocardium angle varies between patients
   2. Orientation occurs by
      1. Realignment of the long-axis
      2. To the perpendicular short-axis slice
      3. In the presence of disease auto-alignment may fail which requires the technologist to adjust it manually
      4. Hence the display above with ETB

3. Segmentation adjustment
   1. AutoQUANT assesses the alignment and allows the user to to further refine it should the segmentation of the LV be incorrect
      1. There is an iterative approach to this process with each iteration slightly redefining the slices
      2. It identifies: extraction, threshold, clustering, and edges
      3. Failure in the auto approach allows the user to intervene
   
   2. 4D-MSPECT takes a slightly different approach with the same results
      1. Looks for basal and apical limits
      2. Places the mid-slice of the short-axis, noting the cross-hairs in the vertical and horizontal long slices
      3. Users is allowed to adjust this parameters
4. Surface rendering in 4D
   
   1. 4D rendering evaluates the 3D slices by determining the epi/endocardial walls to assess wall motion.
      1. Blue area defines perfusion defects
      2. Within the chamber of the LV the apex to base areas that contain the empty pixels calculate the %EF and display the curve
      
      3. This 3D rendering of all slices and all beens results that can be displayed dynamically
      4. ED and ES are noted and identify ischemic disease at the apex
      5. Polar map can be evaluated below
      
      6. Using the same patient data another program rendering the dynamic 4D process can be applied (ETB)
         1. It appears that it has a normal %EF and wall thickening drops in the ANT wall to 25 - 45%
         2. However, evaluating the ED and ES images shows lack of perfusion and/or wall thickening
         3. This area appears ischemic
         4. Polar map display can be evaluated below
   
   2. Coronary arteries with perfusion defects seen in ETB
      1. Blacked out areas appear to be infarct
      2. Gray (reverse distribution) may be ischemic
      3. Overlay of arterial blood flow indicates that LAD is either very stenotic or occluded
5. Polar mapping

   
   1. Cedars, ETB, and Baylor
      1. Using 3D data base and midventriclar walls are determined and mapped using a cylindrical modal
      2. Apex mapping determines a spherical and radial model
      3. These two models are matched to the radioactive distribution resulting in a polar maps
      4. Orientation is the noted with the walls defined in the black box
      5. Apparently assessment can also be done with the RV
   
   2. Displaying the polar map of the disease myocardium is compared with the 2 following imaging
      1. Perfusion defect can be seen
      2. Blackout area further defines it
      3. Reversibility shows that most of it fills in - this is an example of?
6. Scoring
   
   1. This is a 17-sector overlay of a polar map
   2. Calculating the numbers
      1. There are 5 numerical values: 0 = Normal, 1 = Equivocal, 2 = Abnormal, 3 = Severe, and 4 = Absent
      2. Values are automatically determined based on the amount of perfusion
      3. Stress segments are then subtracted by the rest
      4. A net differential is then displayed via numerical values and visual display
      5. Another interesting point is the numerical values displayed in the total Stress (22) and total rest (10)
      6. Difference between the total value is 15

Automated Quantification of Myocardial Ischemia and Wall Motion Defects by Use of Cardiac SPECT Polar Mapping and 4-Dimensional Surface Rendering* by Lin SG, et al. JNMT (2017)