1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [d7c8bcd8-c815-42c8-bbf1-c20e1abad61c] => Array
        (
            [runtime-id] => d7c8bcd8-c815-42c8-bbf1-c20e1abad61c
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [4216b4a1-3b9b-43ce-85af-82349c52b7ac] => Array
                        (
                            [runtime-id] => 4216b4a1-3b9b-43ce-85af-82349c52b7ac
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;dbe0991f995801084122db4f4d76b431dfc7b563
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [6b3b712f-8877-43d1-b59c-f5e2c9f8f468] => Array
        (
            [runtime-id] => 6b3b712f-8877-43d1-b59c-f5e2c9f8f468
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [5b734465-5cf8-4e8b-9829-556983b9341b] => Array
                        (
                            [runtime-id] => 5b734465-5cf8-4e8b-9829-556983b9341b
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;dbe0991f995801084122db4f4d76b431dfc7b563
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [20f80e18-a51a-4db2-be0d-191a3ed3d175] => Array
        (
            [runtime-id] => 20f80e18-a51a-4db2-be0d-191a3ed3d175
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [424df64a-004f-4c23-af16-c2862e2ca2f9] => Array
                        (
                            [runtime-id] => 424df64a-004f-4c23-af16-c2862e2ca2f9
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;dbe0991f995801084122db4f4d76b431dfc7b563
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [d7c8bcd8-c815-42c8-bbf1-c20e1abad61c] => Array
        (
            [runtime-id] => d7c8bcd8-c815-42c8-bbf1-c20e1abad61c
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [4216b4a1-3b9b-43ce-85af-82349c52b7ac] => Array
                        (
                            [runtime-id] => 4216b4a1-3b9b-43ce-85af-82349c52b7ac
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;dbe0991f995801084122db4f4d76b431dfc7b563
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [d7c8bcd8-c815-42c8-bbf1-c20e1abad61c] => Array
        (
            [runtime-id] => d7c8bcd8-c815-42c8-bbf1-c20e1abad61c
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [4216b4a1-3b9b-43ce-85af-82349c52b7ac] => Array
                        (
                            [runtime-id] => 4216b4a1-3b9b-43ce-85af-82349c52b7ac
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;dbe0991f995801084122db4f4d76b431dfc7b563
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [d7c8bcd8-c815-42c8-bbf1-c20e1abad61c] => Array
        (
            [runtime-id] => d7c8bcd8-c815-42c8-bbf1-c20e1abad61c
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [4216b4a1-3b9b-43ce-85af-82349c52b7ac] => Array
                        (
                            [runtime-id] => 4216b4a1-3b9b-43ce-85af-82349c52b7ac
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;dbe0991f995801084122db4f4d76b431dfc7b563
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [d7c8bcd8-c815-42c8-bbf1-c20e1abad61c] => Array
        (
            [runtime-id] => d7c8bcd8-c815-42c8-bbf1-c20e1abad61c
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [4216b4a1-3b9b-43ce-85af-82349c52b7ac] => Array
                        (
                            [runtime-id] => 4216b4a1-3b9b-43ce-85af-82349c52b7ac
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;dbe0991f995801084122db4f4d76b431dfc7b563
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [9a2b3896-b616-4494-961f-58309445eb33] => Array
        (
            [runtime-id] => 9a2b3896-b616-4494-961f-58309445eb33
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [635a95ac-0849-4ab1-9642-3647cfc05863] => Array
                        (
                            [runtime-id] => 635a95ac-0849-4ab1-9642-3647cfc05863
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;dbe0991f995801084122db4f4d76b431dfc7b563
                )

        )

)


  
    





































































    Attenuation of Cerebral Veins in Susceptibility-Weighted MR Imaging Performed with the Patient under General Anesthesia | American Journal of Neuroradiology  
    



















    

































    
  
  




    
    

  

      


    

      

  
  
  

    

  

    

  

                
    

      

  

    

  
      
  
  

    


Advertisement



  



  


  
  



  



    

  


  


  


  
  
  
  
  
  

  	      


    
      

    
  
    
        
    

  

    
                        

  

                
    

      

	  

		
		

			

			  

  
      
  
  

    

  
  
      
LetterLetter

  
      

  
      
Attenuation of Cerebral Veins in Susceptibility-Weighted MR Imaging Performed with the Patient under General Anesthesia
  
    	
C. Kesavadas, B. Thomas, S. Misra and J. Saini

  
    	
American Journal of Neuroradiology September 2008,  29 (8) e71; DOI: https://doi.org/10.3174/ajnr.A1083 

  
  
  



  


  
  



			

		

	
	
 	
	  
  

		
		

			

			  

  
      
  
  

    
  


  
  



  
      
  
  

    

  

    

  
      
  
  

    
One of the most important advantages of susceptibility-weighted MR Imaging (SWI) is the exquisite demonstration of cerebral venous anatomy.1,2 This is useful for detecting developmental venous anomalies and in conditions associated with venous anomalies such as Sturge-Weber syndrome. The demonstration of accentuation of veins due to venous stasis in venous thrombosis or increased oxygen extraction in focal infraction has been described.1
In our pediatric patients in whom MR imaging is performed with the patient under general anesthesia, we have noted that the SWI shows the venous anatomy poorly (Fig 1A, -B) in comparison with those patients in whom the study was performed without anesthesia (Fig 1C). Anesthesia is induced in most of these children with 2%–3% sevoflurane in oxygen, by using a modified Bains circuit and titrated to the loss of eyelash reflex. In the MR imaging suite, anesthesia is continued with sevoflurane in a 1:1 mixture of air-oxygen, administered through the auxiliary gas outlet of the MR imaging–compatible Datex-Ohmeda Aestiva/5 MRI anesthesia ventilator (GE Healthcare, Madison, Wis), with the children breathing spontaneously. In a few of these patients, anesthesia was induced by using intramuscular injection of ketamine and midazolam.
The contrast mechanism in SWI is primarily associated with the magnetic-susceptibility difference between oxygenated and deoxygenated hemoglobin, leading to a phase difference between regions containing deoxygenated blood and surrounding tissues, resulting in signal-intensity cancellation. During anesthesia, on the basis of the depth of anesthesia, the oxygen extraction in the brain tissue is decreased. This decrease, in turn, results in a change in the extent and amplitude of the blood oxygen level–dependent response as has been demonstrated in earlier functional MR imaging studies.3
Initially, we believed that a decrease in deoxyhemoglobin within cerebral veins secondary to oxygen inhalation during anesthesia was responsible for the attenuation of signal intensity. If this hypothesis is correct, then oxygen inhalation can be used for differentiating hemorrhage from vein in SWI. Earlier studies have shown that SWI performed before and after administration of intravenous gadolinium can distinguish both.4 To test this hypothesis, we performed SWI of the brain in an adult patient without and with oxygen inhalation through a mask, which decreased the venous signals, but only marginally.
Retrospectively when we reviewed the SWIs of patients under anesthesia, we noted that the attenuation of signal intensity was present in all the patients but varied among patients. This made us think that the depth of anesthesia is probably responsible for this variation. Therefore, we think that cerebral oxygen extraction depending on cerebral metabolism and, to a lesser extent, oxygen saturation contribute to the observed SWI signal intensity. We are planning prospective studies on the influence of the depth of anesthesia on signal-intensity attenuation of veins in SWI.

      
    
  Fig 1. 

          Fig 1.
         
SWI minimal-intensity projections. A, A 6-year-old child in whom SWI was performed after anesthesia using sevoflurane. B, A 17-year-old boy in whom SWI was performed after anesthesia using ketamine and midazolam. C, A 6-year-old boy in whom SWI was performed without anesthesia.
References
  1. ↵
    Tong KA, Ashwal S, Obenaus A, et al. Susceptibility-weighted MR imaging: a review of clinical applications in children. AJNR Am J Neuroradiol 2008;29:9–17
    Abstract/FREE Full Text
  2. ↵
    Thomas B, Somasundaram S, Thamburaj K, et al. Clinical applications of susceptibility weighted MR imaging of the brain: a pictorial review. Neuroradiology 2008;50:105–16. Epub 2007 Oct 11.
    CrossRefPubMed
  3. ↵
    Marcar VL, Schwarz U, Martin E, et al. How depth of anesthesia influences the blood oxygenation level-dependent signal from the visual cortex of children. AJNR Am J Neuroradiol 2006;27:799–805
    Abstract/FREE Full Text
  4. ↵
    Lin W, Mukherjee P, An H, et al. Improving high-resolution MR bold venographic imaging using a T1 reducing contrast agent. J Magn Reson Imaging 1999;10:118–23
    CrossRefPubMed
  


  
  



  
      
  
  

    
  


  
  



  




  


  
  



  
      
  
  

    
  


  
  



  
      
  
  

     Back to top  


  
  



			

		

		
		

			

			  

  
        
In this issue

    
  
  

    
  


  
  



  
      
  
  

    

  

    

  
      
  
  

    


Advertisement



  



  


  
  



  



  


  
  



  
      
  
  

    

	  
  

		

          

            

  
      
  
  

     Print  


  
  



  
      
  
  

     Download PDF  


  
  



  
      
  
  

    
 Email Article
  


  
  



  
      
  
  

    
 Citation Tools
  


  
  



          

        

        
        

          

            



  
      
  
  

    

  

    

  
      
  
  

    

  
  
  
  
      
Attenuation of Cerebral Veins in Susceptibility-Weighted MR Imaging Performed with the Patient under General Anesthesia
  
    	
C. Kesavadas, B. Thomas, S. Misra, J. Saini

  
    	
American Journal of Neuroradiology Sep 2008, 29 (8) e71; DOI: 10.3174/ajnr.A1083 

  
  
  



  


  
  



  
      
  
  

    

  
    
  
  
    
  
  
    
  


  


  
  



  
      
  
  

    
del.icio.us logo Twitter logo Facebook logo Mendeley logo
  


  
  



  



  


  
  



  
      
  
  

    
  


  
  



          

        

	
 	
	
	


  


  
  



  
      
  
  

    
              Purchase  


  
  



  
        
Jump to section

    
  
  

    
  


  
  



  
      
  
  

    
  


  
  



			

		

	
	
 	
	
	


    

  



  

                
    

      

  

    

  
      
  
  

    


Advertisement