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Letter to the Editor
Comment on the article What constitutes the M1 segment of the middle cerebral artery?
  1. Donald Lobsien1,
  2. Matthias Gawlitza1,
  3. Karl-Titus Hoffmann1,
  4. Benjamin Friedrich2
  1. 1Department of Neuroradiology, Leipzig University Hospital, Leipzig, Germany
  2. 2Department of Diagnostic and Interventional Radiology, Leipzig University Hospital, Leipzig, Germany
  1. Correspondence to Dr Benjamin Friedrich, Department of Diagnostic and Interventional Radiology, Leipzig University Hospital, Liebigstr 20, Leipzig 04103, Germany; b.friedrich{at}

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We read with great interest the article by Goyal et al.1 We would like to draw your attention to four recently published papers that deal with the important aspect mentioned in their article—“[…] The discussion about where the M1 stops and where the M2 starts is therefore an artificial one, necessitating a more ‘practical’ approach for everyday work […]”.

This ‘more practical’ approach exists. It was described by our group in two papers covering CT angiography (CTA) and two MR angiography (MRA), all in 2015.2–5 We called it the ‘distance to thrombus’ (DT). It is a measurement (in mm) of the distance from the carotid T to the start of the occlusion of the middle cerebral artery (MCA), in the form of a curved line, carried out on thick-slab coronal maximum intensity projection images (which the authors mentioned as their ‘money images’), see figure 1.

Figure 1

Part of image (A) of figure 2 in the article by Goyal et al. The red line indicates the distance to thrombus. The length can only be estimated as this was not obtained by a calibrated screenshot, but is probably <16 mm.

We showed in our study on acute MCA occlusions that this parameter could be used to identify precisely with CTA and MRA those patients with a very low probability of a good long-term outcome after systemic thrombolysis.2 ,3 Additionally, we showed that patients with a DT <16 mm treated with systemic thrombolysis in combination with mechanical thrombectomy have a significantly improved long-term outcome in comparison with a matched group who received only systemic thrombolysis.4 We also showed that DT inversely correlates with Tmax perfusion maps and is an independent predictor of target mismatch identified by MRI.5

We agree strongly with the authors that the use of the classic MCA segment anatomy for studies and clinical patient management is impractical in many aspects. That is why we developed and investigated the DT, which we think can overcome most of these problems.


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  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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