Q & A about NMR and MRI

What is the marginal cost of an MRI, CT, and X-ray scan?
Preferably with all the components of cost (depreciation, power, staff, maintenance, etc) and with a source?

Source: Taiwan’s NHI (National health insurance) payment (in Chinese)
33070B CT without contrast: 3800 points
33071B CT with contrast:4560 points
33072B CT with and without contrast: 5035 points
33084B MRI without contrast: 6500 points
33085B MRI with contrast: 11500 points
32001C Chest X-ray: 200 points
1 points = 0.8~0.9 NTD, 1 NTD = 0.03 USD

It includes imaging and reading. If the film is not read by a bordered radiologist, the NHI will not pay.

I assume that by marginal cost you mean something like the average cost per study, factoring in amortization of the machine, materials, salaries for technical personal AND cost of interpretation by a radialogist (I am not an accountant so I am not sure what the proper term for all of this is). The cost vary depending on the precise type of study done (some studies involve injecting a contrast agent, MRI of the spine take longer than the brain, etc), and the volume of studies done.
The best info I could find was at Healthcare Bluebook. They suggest a “fair price” (in a competitive market I think this would be close to the price you are looking for) is $408 for a CT of the brain, $731 for an MRI of the brain, both non-contrast. The numbers quoted by another respondent (Mr. Kalariya) are probably the “chargemaster” charges for the studies. Such numbers are essentially made up out of thin air by hospitals. Almost nobody pays that much.

How are NMR spectra acquired?
Answering your clarification in the comment, which was “What exactly happens between the time you pulse the sample with a magnetic field to when you have the final spectrum?”

First of all, it’s a radio frequency pulse, the field is held constant. There are usually many pulses in an NMR experiment, especially if you’re after 2D or 3D spectra. In any case, after the last pulse, the spin system is still “ringing” for a little while (a few seconds), emitting exponentially decaying radio frequency signal. It is recorded by RF coils in the probe (same coils that generate the pulses. They are often cryogenically cooled for sensitivity). That signal is digitized and stored as files which you can download from the spectrometer. There are several mathematical operations that can be done to these time domain spectra (multiplying by differently shaped functions, etc), but sooner or later it goes through digital Fourier transform, which produces the frequency-domain spectrum you know.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s