Some problems with MSCC

SCT
1

Hello, this inquiry is primarily about the standardized MSCC method.
Regarding the MSCC formula, does this method require that there be no compression above and below the level of compression? In other words, is this method suitable only for patients with single-level compression? If there is spinal compression at levels above or below, the standardized MSCC assessment may be inaccurate.

2

Hello,

Thanks for the great question.

If there are multiple levels of compression, it is important to label all of them. During the MSCC computation, normalization will be done based on the healthy levels above above all the compressed ones. The tutorial here shows how to label multiple levels of compression.

Best,

Sandrine

3

Thank you for your explanation. So, can I assume that the MSCC algorithm built into the SCT is accurate as long as I have labeled all levels of spinal cord compression? This is because in our image analysis, the cerebrospinal fluid space above and below the level of the primary lesion is often compressed as well, as shown in the figure below.

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The primary lesion is at the C4/5 level, with compression present both above C4 and below C5. However, according to the standardized MSCC calculation in the SCT, if the formula is ma/maHc + mb/mbHc, then ma and mb would no longer represent the normal spinal cord area and anteroposterior diameter if those reference levels are also compressed.

Therefore, if I label all the compressed levels (C3/4, C4/5, C5/6), will the software automatically select normal, uncompressed spinal levels above all the labeled compressions to determine ma and mb, ensuring an accurate MSCC calculation?

4

Hello,

Thanks for the details.

The selection of uncompressed levels above and below the labeled compressions is controlled by the -extent and -distance arguments of the sct_compute_compression function:

  -extent <float>       Extent (in mm) to average metrics of healthy levels in superior-inferior direction. (default: 20.0)
  -distance <float>     Distance (in mm) in the superior-inferior direction from the compression to average healthy slices. (default: 10.0)

Figure 1 from this paper illustrates this process.

Looking at your figure, I would personally consider labelling also C6/7 as CSF at this level is clearly reduced.

Best,
Jan