Not necessarily correct. Encourage subjects to think positively. The physiological curvature of cervical spine is based on the standing plain film. However, both CT and MRI are lying down, which will lead to illusion for this reason. Chin up and chin up will have completely different images. The solution is to relax naturally when scanning, and don't deliberately lower your head or raise your head. The scanning results are not much different from plain films. I value of natural enrichment 12C is zero, and there is no NMR signal. The I value of 13C is 1/2, and there is a nuclear magnetic resonance signal. Generally speaking, the carbon spectrum is 13C NMR * * * vibration spectrum. Since the spin quantum numbers of 13C and 1H are the same, the principle of NMR * * * oscillation of 13C is the same as that of1h. However, the γ value of 13C core is only about 1/4 of 13C core, and the detection sensitivity is proportional to γ3, so the detection sensitivity of 100% core is only 1/64 of 13C core, plus 65438. This shows that the sensitivity of different nuclei detected in the same magnetic field is very different, and the natural abundance of 13C is only 1. 108% of that of 12C. 13C is technically more difficult to detect than 1H because of its low sensitivity and abundance.