Yes but there are some limitations.
1) You can use a USB based Twain Scanner thru native USB Redirection (VMWare, Microsoft RemoteFX or Citrix XenDesktop)
2) If you have only Terminal Server you can also try Fabalutech's USB Redirection for Remote Desktop's, Fabulatech is available for Citrix XenApp and Microsoft RDP and require an add-on licensed Software running on the Server.
Please note: If using USB Redirection don't blow up you LAN / WAN, Scanning a lot of "high quality" pictures will produce a lot of traffic!
3) You can try SANE, SANE is a not documented / not official feature and is not related to any protocol like RDP,ICA or other. The configuration is also a little bit tricky. Please note: This feature is not an official mentioned feature and the support here is very limited!
- You need to figure out if the used scanner is supported in general for SANE use (check at http://www.sane-project.org)
- You need to deploy the required scanner firmware to the client folder /wfs/usr/firmware, firmwares can be found here http://www.meier-geinitz.de/sane/gt68xx-backend
- You need to install the server component, download is available here http://sanetwain.ozuzo.net
- After this is done you need to enable in the local IGEL Setup or the UMS Profile the setting System->Registry->Network->saned->enabled
For variant 3 please note: No support, no warranty or anything else from anybody! It can work but it don't have to be...