Reply
=====

* Stuart C. Coley
* Charles A.J. Romanowski
* Tim J. Hodgson
* Paul D. Griffiths

The preliminary results of imaging intracranial vascular malformations with time-resolved MR angiography as presented by Klisch et al (1) were not referenced in our recent case report (2). This was an omission for which we apologize. Their intimation, however, that we deliberately committed “academic fraud” is totally unfounded and deeply offensive. We strongly encourage the readers of the *AJNR* to read their article, not because it is a landmark publication but to illustrate why our report is far from redundant.

The article by Klisch et al (1) is essentially a preliminary technical report. They describe a technique for dynamic MR angiography that is different from ours in many respects, including bolus dynamics, image acquisition, postprocessing, and image analysis. Furthermore, we attempted to explore the value of this technique in clinical practice. Klisch et al failed to include any clinical information for either of their two patients with dural AVF, and no description of any other imaging findings was presented. One dural AVF was presented as a figure with rudimentary annotation; the other was not described at all. No attempt was made to classify lesions, and no discussion of the ability of the technique to show both pathologic and normal patterns of venous drainage and the relevance of these findings to prognosis and treatment was presented. Their use of a signal intensity time curve (for an arteriovenous malformation) to show early opacification of the venous structures that is self evident from the 2D MR angiograms is facile, as is the disappearance on MR angiograms of an embolized arterial pedicle.

We proposed for the first time, and described, the use of signal intensity time curves to potentially identify those dural AVF that cause venous hypertension and to monitor the effects of intervention. We also included, albeit as an addendum, our success in showing Djindjian type 3 cortical fistulae by using dynamic MR digital subtraction angiography. We now have experience with using MR digital subtraction angiography for the detection of 14 dural AVF, but are we to assume that any future publications on this topic will be worthless?

This is the second time that Klisch et al have chosen to complain to the *AJNR* that their work had not been referenced (3). Their same article (with a total of two cases of arteriovenous malformation) was also mentioned when we published our preliminary experience with 20 cases of arteriovenous malformation during the same year (4). We were criticized for not including two references from their article, even though they were published after the submission of our article to the *AJNR*. Furthermore, the contribution of Hennig and Strecker (5) on dynamic MR digital subtraction angiography was duly recognized in our article.

In the past we have always found it rather amusing to listen to other authors sqaubbling in international journals. Surely, letters such as these are what constitute redundant publications; publications that exist only to lengthen curriculum vitae and increase citations rather than increase the body of knowledge regarding early clinical experience with an exciting technique. If anyone should feel aggrieved by the inadequacy of our reference section, it should be Wetzel et al (6) and Aoki et al 7), and it is right that we acknowledge their early work with dynamic angiography.

## References

1.  Klisch J, Strecker R, Hennig J, Schumacher M. **Time-resolved projection MRA: clinical applications in intracranial vascular malformations.** Neuroradiology 2000;42:104–107
    
    [CrossRef](http://www.ajnr.org/lookup/external-ref?access_num=10.1007/s002340050024&link_type=DOI) 
    
    [PubMed](http://www.ajnr.org/lookup/external-ref?access_num=10663484&link_type=MED&atom=%2Fajnr%2F23%2F9%2F1614.1.atom) 

2.  Coley SC, Romanowski CA, Hodgson TJ, Griffiths PD. **Dural arteriovenous fistulae: noninvasive diagnosis with MR digital subtraction angiography.** AJNR Am J Neuroradiol 2002;23 ;404–407
    
    [Abstract/FREE Full Text](http://www.ajnr.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiYWpuciI7czo1OiJyZXNpZCI7czo4OiIyMy8zLzQwNCI7czo0OiJhdG9tIjtzOjIyOiIvYWpuci8yMy85LzE2MTQuMS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=) 

3.  Klisch J. **Dynamic MR digital subtraction angiography.** AJNR Am J Neuroradiol 2001;22:1632
    
    [FREE Full Text](http://www.ajnr.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiRlVMTCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiYWpuciI7czo1OiJyZXNpZCI7czo5OiIyMi84LzE2MzIiO3M6NDoiYXRvbSI7czoyMjoiL2FqbnIvMjMvOS8xNjE0LjEuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9) 

4.  Griffiths PD, Hoggard N, Warren DJ, Wilkinson ID, Anderson B, Romanowski CA. **Brain arteriovenous malformations: assessment with dynamic MR digital subtraction angiography.** AJNR Am J Neuroradiol 2000;21:1892–1899
    
    [Abstract/FREE Full Text](http://www.ajnr.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiYWpuciI7czo1OiJyZXNpZCI7czoxMDoiMjEvMTAvMTg5MiI7czo0OiJhdG9tIjtzOjIyOiIvYWpuci8yMy85LzE2MTQuMS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=) 

5.  Hennig J, Scheffler K, Laubenberger J, Strecker R. **Time-resolved projection after bolus injection of contrast agent.** Magn Reson Med 1997;37:341–345
    
    [PubMed](http://www.ajnr.org/lookup/external-ref?access_num=9055222&link_type=MED&atom=%2Fajnr%2F23%2F9%2F1614.1.atom) 

6.  Wetzel SG, Bilecen D, Lyrer P, et al. **Cerebral dural arteriovenous fistulas: detection by dynamic MR projection angiography.** AJR Am J Roentgenol 2000;174:1293–1295
    
    [PubMed](http://www.ajnr.org/lookup/external-ref?access_num=10789780&link_type=MED&atom=%2Fajnr%2F23%2F9%2F1614.1.atom) 

7.  Aoki S, Yoshikawa T, Hori M, et al. **MR digital subtraction angiography for the assessment of cranial arteriovenous malformations and fistulas.** AJR Am J Roentgenol 2000;175:451–453
    
    [PubMed](http://www.ajnr.org/lookup/external-ref?access_num=10915693&link_type=MED&atom=%2Fajnr%2F23%2F9%2F1614.1.atom) 

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