4.2 | Spectrum characteristics
NAA showed the highest peak in 3.0T1H-MRS detection of
normal brain tissue, which could reflect the functional activity and
density of neurons 1. Because NAA was only stored in
neurons, and the content of neurons in nasal polyps was significantly
reduced, the peak value of NAA decreased significantly. Cho plays an
important role in the evaluation of tumor cell metabolism. Due to the
abnormal proliferation of nasal polyp cells, the cell metabolism level
is high and the material exchange is strong, so the Cho summit appears
to increase. Cho is a choline complex. These complex peaks include
phosphatidylcholine, glycerophosphingobiline and other substances.
Through these complex peaks, the specific condition of patients can be
directly reflected2-3; Ace stands for acetate, the
dissociated form of acetic acid, Because the pka of fatty acid carboxyl
group is about 4.8, usually the pH value of plasma is 7.4, and the pH
value of intracellular fluid is 7.0, so almost all the fatty acid
molecules in body fluid (99.9%) are in dissociation state, that is,
acetic acid exists in body fluid in the form of anion4, because of the rapid growth and obvious hyperplasia
of nasal mucosa polyp, the content in polyp tissue increases
significantly (this can be considered as nasal mucus) The most typical
characteristic of the spectrum of membranous polyps); ace can also be
produced by bacteria, It is also an important marker of anaerobe
infection. Therefore, in the long-term growth process of nasal polyps,
due to blocking the ostium of the sinuses or preventing the outflow of
secretions from the ostium, it is easy to lead to the degeneration,
necrosis or liquefaction of the inside of the sinuses or the polyps
themselves due to bacterial infection, and finally form a purulent or
mucopurulent abscess like substance. The creatine complex (Cr) contains
creatine and phosphoric acid When the energy metabolism of creatine
decreases, Cr increases, and the higher the peak value of Cr, the worse
the metabolism of brain tissue; Lac is stored in the extracellular and
intracellular space, mainly composed of two resonance peaks, which are
also called double lines in medical circles; when TE is 288, the double
peaks are upward, when TE is 144, the double peaks are
downward1-7. In the healthy state, cells are mainly
aerobic metabolism, Lac peak is trace or none; the growth block of nasal
polyp tissue has an inhibitory effect on cell aerobic respiration, and
glycolysis will be strengthened, so Lac peak is increased6-10. The degree of necrosis and degeneration of nasal
polyps was in direct proportion to the decrease of NAA and the increase
of Cho. Ace, Cho, Lac, NAA are highly specific in the diagnosis of nasal
polyps. The peak of Ace is significantly higher (which can be considered
as the most typical feature of the spectrum of nasal polyps), Cho is
higher, Lac is higher, Lac / Ace ratio is significantly lower, Cho / NAA
ratio is significantly higher, Lac / NAA ratio is higher, which provides
an objective basis for the diagnosis of nasal polyps.
In a word, on the basis of other imaging examination, the spectrum
analysis of 3.0T1H-MRS can get the biochemical
metabolism information of clinical value of nasal mucosa polyp.
The value of Ace in nasal polyps was“11.43 ± 6.11”, NAA (17.76 ±
6.20), Cho (23.19 ± 6.91), Lac (12.51 ± 3.42), Lac / Ace (1.09 ± 0.56);
Cho / NAA (1.34 ± 1.10), Lac / NAA (0.70 ± 0.55). According to the
different characteristics of Cho, Cr, Lac, Ace peak integral value and
the ratio of each integral value, it is helpful for the correct
diagnosis of nasal mucosa polyp.