Talk:PET-MRI

Attention (still) needed

I've started to tidy up this article, but it's still a bit of a mess. It reads more like a selection of snippets from sales brochures, rather than an encyclopaedic article. My time is rather limited, so I'm writing this here as a reminder to myself, or some pointers for anyone else who fancies having a go. These are still missing from the article, in no particular order:

• A discussion comparing sequential (Philips) to true simultaneous PET/MR
• Interactions between PET and MR systems
• Detectors: why classic photomultipliers don't work in a magnetic field, avalanche photodiodes, silicon photomultipliers
• Better localisation due to spiral path of positron in a magnetic field
• Typical construction: subject, RF coil, PET camera, rest of MR system
• More detail about strengths of MR, PET, and how combination may be used (e.g. co-registration of PET data onto MR data, MR data for attenuation correction)

GyroMagician (talk) 13:06, 5 January 2014 (UTC)

I've added a fair amount of editing and also some citations to the Citation Needed requests in the article. Although I didn't add them to the article I will simply respond (in order) to the above request for information with my own information without citation or reference, as there is certainly a fair amount of discussion on these topics in the industry, and this can be considered my opinion as opposed to fact by many people:

• Sequential vs Simultaneous - Sequential has always existed since the advent of imaging networks. Simultaneous advantages are incredible in the X,Y,Z and time correlations. Basically, 4 dimensional imaging improvements and motion correction considerations. Please reference this article, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2934593/ .
• Interactions - I'm not sure how to handle this request. Can some examples of the information desired or a more specific question be offered?
• Photomultiplier tubes - PMT's use typical "tube" technology, thus the electron beam stream is extremely susceptible to magnetic influence. Simply put, "tube" amplifers and technology can not operate within the magnetic fields used in MRI. APD's and SIPM's can be better explained by simple links to existing WIKI information. As far as MR/PET usage, APD's effectively operate as equivalent "tube" amplifier technology and are NOT susceptible to magnetic field influence. APD = Digital PMT, per se. SIPM's are basically "many" APD's on a single layer that improve control and resolution of the signal as well as provide timing resolution improvements (important in PET).
• All PET scanners suffer from a "tolerance" band for physical X,Y,Z isolation of the event due to timing limitations and the statistical reality that a positron travels in a fullly sphereical random direction following creation prior to annihilation. This reality effectively limits the resolution to 2mm regardless of how good the timing resolution is. thus, image quality is more greatly influenced by the statistics (quantity) of events and accurate placement of the LOR, rather than the timing (physical improvement of X,Y,Z with <2mm resolution) of the event.
• For answer to construction I will provide the reference above again, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2934593/ , and state that the present MR/PET system offered by Siemens is an insert system that has sequential capability. The actual physical construction I will search for publically available references to link to in the future.

Kkadams115 (talk) 19:17, 16 January 2014 (UTC)

Move discussion in progress

There is a move discussion in progress on Talk:PET/CT which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 06:45, 7 January 2014 (UTC)