New Development of MRI examination of gastric cancer

By | March 30, 2012

In recent years, with the magnets, coils and other hardware advances in technology, MRI imaging speed, image acquisition significantly improved the efficiency and resolution; the development and application of new sequences, an increase of gastric contrast, enriching the diagnostic information; before the disposal of standardization, gastric motility and morphology make up for deficiencies varied only on MRI at the inherent advantages of high soft tissue resolution, more conducive to the gastric localization and qualitative diagnosis, preoperative staging and treatment evaluation provided a wealth of information.
Advances in technology and new MRI examination of gastric cancer (1) Magnetic resonance imaging: Magnetic resonance imaging (MR hydrography) technology has been made since 1991, through continuous improvement and becoming more mature and expanding range of applications. The principle mainly based on static or slow the flow of body fluids with long T2 relaxation showed high signal T2 relaxation values of the surrounding tissue showed low signal characteristics of a short, Stuttgart with long TR long TE produces heavy T2 effect of making water organ development. Magnetic resonance imaging of gastrointestinal (magnetic resonance gastrointestinal hydrography, MRGIH) is in the fast scanning method appears to achieve, preliminary results have shown that magnetic resonance imaging study in the field of gastrointestinal value.
Gastrointestinal contrast agent with the collar or the CT examination compared, MRGIH has the following advantages: The method is simple, rapid diagnosis; easy to find lesions and lesion localization; from the lock agent of high concentration, no artifacts problem, the lock agent Check the gastrointestinal tract in patients with MR can be immediately checked; MRGIH no ionizing radiation, can be used for pregnant women and children.
I found that a single shot two-dimensional projection thick Magnetic resonance imaging of the gastrointestinal tract, and its image quality is better than three-dimensional MIP images. Because it is single element imaging, in any plane have the same spatial resolution, higher image quality, structure, clear display. MIP reconstruction technique to overcome the errors arising due to recording artifacts and accurate reconstruction of defects. Since the existence of gastrointestinal motility, MIP capture images a long time, scanning the small range of gastrointestinal tract is not suitable for three-dimensional imaging examination. Thick layer of single-shot shot imaging technology is simple, short imaging time, it can be repeated, multi-angle, multi-dimensional imaging, have a similar effect of three-dimensional rotating images, make up two-dimensional structure of overlapping of the shortcomings observed; the imaging time is short, only 6s, can effectively reduce the stomach and intestines on the imaging quality.
Advances in technology and new MRI examination of gastric cancer (2) MR Perspective: X ray and ultrasound due to complete in a few milliseconds, the image acquisition, thus ensuring a better spatial resolution in the case, be very fast image update rate, Dynamic observation of the image and then complete the process perspective. MRI imaging is slow because conventional can only get a static image. But with a small angle on the short TR gradient echo implementation of applications such as turboFLASH such sequences, the original data acquisition speed can already achieve sub-second. For MRI imaging, in addition to the original image data acquisition, image of the original data transmission speeds increase the image reconstruction is a prerequisite to achieve this goal. Multi-parameter control of the RARE sequence, the inspection of abdominal pelvic ultrasound has the effect can be obtained in real time; charges fast Cine sequence, also had heart and great vessels are similar to real-time imaging results. With the sequence of technology development, is expected in the future for the diagnosis of stomach cancer activity, and other new basis.
Advances in technology and new MRI examination of gastric cancer (3) three-dimensional MR imaging: three-dimensional spiral CT imaging technology is relatively mature, more relevant research reports, MRI three-dimensional CT imaging continues the related three-dimensional imaging instruments, including the MIP, MPR, SSD and VIE (virtual intraluminal endoscopic views) and other technologies. Our study found that, according to the different viewing angle, three-dimensional reconstruction can be virtual endoscopy, gas cast, simulated lumen, three-dimensional profiles and other images. Endoscopy can be observed within the lumen of gastrointestinal conditions; gas cast get the overall outline of the gastrointestinal tract like; simulation of the gastrointestinal lumen cavity method can also be observed within and outside the contour; cut images of simulated lumen, which access to the profile of the gastrointestinal tract to achieve on local observations. Different imaging methods on morphological and pathological signs of gastrointestinal tract, the display ability of a more obvious differences, simulated mold cavity and gas anatomical relationship between the display and the mucosal lesion morphology and localization capability in the best; and display of cancer uplift, collapse of house, ring dikes, Jie mucosal folds, luminal narrowing and wall stiffness, the simulation of the lumen, gas cast and three-dimensional profile images are superior to virtual endoscopy; on the uplift capacity of lesion detection, the simulation lumen, gas cast and virtual endoscopy were no significant differences between the three-dimensional profile image more suited to bulge at the base display.
Although the three-dimensional three-dimensional CT with MRI compared with no radiation, high soft tissue resolution of the merits at this stage due to technical factors, the application of relatively small; future development, yet to be the emergence of new sequence and improved spatial resolution.
Advances in technology and new MRI examination of gastric cancer (4) MRI studies in vitro high-resolution (high resolution magnetic resonance, HRMR): high soft tissue resolution is one of the advantages of MRI imaging for the detection and staging of gastric cancer has important significance, but because technical conditions, such as motion artifacts, coil technology is lagging behind other factors, this advantage has not been fully realized. To explore the signal characteristics of each layer and gastric pathology to correspond with, and tap the potential advantages of MRI applications, paving the way for the future development path, but also to enhance the application of MRI in the diagnosis of gastrointestinal confidence to the stomach in vitro high-resolution MRI study .
Key means to achieve high-resolution three: absolute rest, completely eliminate the interference of motion artifacts; gastric wall close to the coil and, by shortening the distance to the purpose of increasing the signal to noise ratio; through the high-field, narrow FOV and increase the matrix, to achieve improved spatial resolution.
HRMR identifiable layers of the stomach are different, reported 3-6 months. Distinguish the layers of the structure and pathology in the stomach there is a good correlation. Sato (2004) 6 new study distinguished layer, respectively, mucosa, muscularis mucosa, submucosa, muscularis propria, subserosa and serosa. Through a set of preliminary findings, HRMR can still distinguish the hierarchical structure of the muscularis propria, gastric wall can be displayed up to a total of 8-layer structure.
Advances in technology and new MRI examination of gastric cancer (5) nuclear magnetic resonance endoscopy (magnetic resonance endoscopy, MRE): MRE concept of Inui from Japan first proposed in 1995. In order to achieve the effect of high-resolution MRI in vivo, learn EUS (EUS) concept, a non-ferromagnetic coil made of the small diameter of 12.7mm, the first end fixed to the endosc
ope through the stomach into the cavity, shorten the The distance between the two, increasing the contact surface coil and the stomach, to improve the spatial resolution effect. Combined with multi-directional scanning and rapid sequencing technology, and can be distinguished stomach 3-5 layers. There are reports of gastric cancer detection rate was 100%, T staging accuracy rate of 100%.
Conventional endoscopy can only get information on the surface of the stomach cavity, MRI has the advantage of both endoscopic observation of surface morphology of the stomach cavity, stomach and can distinguish between the organizational structure, location of cancer, determine the location of biopsy derived more advantages At the same time it is observed over larger EUS with conventional scanning combined for simultaneous gastric T, N, M stage, in order to achieve a real sense of "one-stop stage."

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