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F19 spectroscopy -- { F19 references }
C13 spectroscopy -- { C13 references }
Here is a brief summary of Peter's questions & his collected answers (somewhat annotated by me, of course!).
1) What can be do in terms of NMR-spectroscopy using an MRI whole body 1.5 T imaging system?
a) 1.5T (Tesla) is equivalent the a conventional NMR operating at roughly 63.9 MHz (42.5759 Mhz/T for proton). Early NMR spectrometers were 40 MHz, and much work has been done at 60 MHz!! Of course, resolution may be a question (see note above about spinning of the patient!).
b) Sensitivity (S/N) is course is field dependent, but a human has a lot more spins than you can jam into a 5 mm NMR tube! Of course, to get any useful information from such an inhomogenous sample (a human), you need small volume data sampling techniques to localize on the order of 5cc volumes. The smaller the volume, the longer the acquistion times to get the S/N desired.
c) 2T, 3T, and 4T whole body systems are also in use (mostly as research systems, and certianly fewer than the 1.5T clinical systems).
2) Are they limited to H1 and 31P?
b) F19 spectroscopy/imaging
c) Li7 spectroscopy
d) Na23 spectroscopy/imaging
3) Is it possible to do C13 with high power decoupling safely?
a) C13 spectroscopy with WALTZ decoupling for example.
b) P31 decoupling is also being used to improve resolution and hence S/N in small volume (CSI type) experiments.
c) Total SAR with decoupling still needs to be monitored!
4) Is it possible to do Inverse spectroscopy?
a) Yes, but like decoupling, it is not standard.
5) Does spectroscopy at these low fields really tell you anything useful yet (considering S/N and resolution)? YES! Is NMR spectroscopy really used clinically anywhere or is it still just a research oriented activity?
a) "That's a religious issue." Not entirely, but on certian specific disease states give clinical diagnostic information.
b) There are many studies that give useful research information.
c) No one is being reimbursed by the insurance companies yet!
6) How easy is it to modify pulse programs and to process spectroscopy data using arbitrary windows, etc?
a) (my note here) I'm biased, but neither is real hard compared to early NMR systems! I still have some data on paper tape!!
b) GE's PROBE (Proton Brain Exam) product is fully automated.
c) Given the state of networking today, off-line processing is popular, since scanner time is too expensive.
7) Are the data files easy to transfer and process using third-party software? (I guess I am asking if the fileformats are 'public'.)
a) GE file formats are public. (available as a service document, I believe)
b) See David Clunie's Medical Image Format FAQ.
c) See Peter Lundberg's own list of NMR Software!!!
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