| Objective（s）:To verify low b values using homemade in vitro cyst model（b=100s/mm2）Accuracy of DWI in identifying large occipital pools and large arachnoid cysts and applying them in clinical practice.Methods:1、Establish the model:design two sets of in vitro cyst models.Cyst model a simulation imaging:take three exactly the same size of Plexiglass hollow ball（R=1.0cm）,respectively on the surface of drilling radius（R=0.06cm）hole 0,1,2,simulate ideal cyst,slow traffic cyst,rapid traffic cyst,in the Netherlands Philips Ingenia 3.0T magnetic resonance scanner using T1WI sequence scanning,simulate the process of cyst imaging.The maximum level of different types of simulated cysts were selected on the Philips Extended MR Workspace post-processing workstation,and the signal values were determined at 2min,10min,20min,30min,1h,1.5h,2h,12h,and 24h,so as to draw the time-signal line map and observe the changes.Cyst model 2 simulates no flow/flow of cerebrospinal fluid:high and low b values（1000,100s/mm2）DWI scanned the three types of plexiglas hollow balls in the cyst model 1,which were divided into simulated cerebrospinal fluid nonflow group and cerebrospinal fluid flow group.The DWI sequence scan data were reconstructed by post-processing software to obtain ADC plots,respectively ADC1000graph and ADC100graph.The ROI of the simulated CSF and the central drawing of different types of simulated cysts were selected on the two groups of ADC maps to measure the ADC values.Statistical analysis was performed using SPSS26.0 software with high and low b values（b=1000,100s/mm2）ADC values between the two groups using t test;the same b value（b=1000 or 100s/mm2）ADC values were compared between three or more groups;P<0.05.2、Clinical application:Analysis from January 2022 to March2022,during which routine brain MRI and high and low b values（1000,100s/mm2were performed in Yuxi People’s Hospital）DWI examined the clinical and imaging data of the patients,and the patients with the enlarged pillow pool area were included in the observation objects,respectively,in their ADC1000Figure and ADC100.The ROI was drawn for the arachnoid cyst of the large occipital pool,and the ADC value was measured.The ADC value of the arachnoid cyst was ADCAC;The bridge-front pool is the ADCP.Statistical analysis was performed using SPSS26.0 software with high and low b values（1000,100s/mm2）.The ADC values between the two groups were compared using the t-test.Statistical results were expressed as P<0.05.Results:1、Model part:cyst,model 1:（1）the simulated ideal cyst showed no contrast agent filling within 24h,The cyst signal value was significantly lower than that of the surrounding simulated cerebrospinal fluid;（2）Simsimulated slow traffic cyst can be seen at 30min,Signal values at 1.5h were similar to the surrounding simulated CSF,At 12h,the scanning signal was slightly higher than the surrounding simulated CSF,At 24h,the scanning signal value was still slightly higher than that of the surrounding simulated cerebrospinal fluid;（3）The simulated rapid transit cyst can be filled with contrast agent immediately after scanning begins,And the signal values were higher than the surrounding simulated CSF,The nal values at 12h were slightly higher than the surrounding simulated CSF,The scan signal value at 24h was already close to the surrounding simulated CSF.Cyst model 2:（1）when simulated cerebrospinal fluid does not flow:the ADC value of simulated cerebrospinal fluid,simulated ideal cyst,simulated slow traffic cyst and simulated rapid traffic cyst is at b=1000s/mm2Groups,respectively,（1.99±0.02）×10-3mm/s2、（1.99±0.03）×10-3mm/s2、（1.97±0.03）×10-3mm/s2、（1.97±0.03）×10-3mm/s2;At b=100s/mm2Groups,respectively,（2.14±0.04）×0-3mm/s2、（2.14±0.05）×10-3mm/s2、（2.13±0.05）×10-3mm/s2、（2.14±0.05）×10-3mm/s2;The difference was statistically significant（P<0.05）.ADC of simulated CSF/simulated ideal cyst,simulated CSF/simulated slow transit cyst,simulated CSF/simulated rapid transit cyst,with a ratio at b=1000s/mm2Groups are respectively 1.00±0.01、1.01±0.01、1.01±0.01;At b=100s/mm2Groups are respectively 1.00±0.02、1.00±0.03、1.00±0.02;There difference no significant（P>0.05）.（2）When simulating cerebrospinal fluid flow:the ADC value of simulating cerebrospinal fluid,simulating ideal cyst,slow traffic cyst and rapid traffic cyst is at b=1000s/mm2Groups,respectively,（3.54±0.08）×10-3mm/s2、（2.02±0.08）×10-3mm/s2、（2.00±0.08）×10-3mm/s2、（2.02±0.08）×10-3mm/s2;At b=100s/mm2Groups,respectively（30.22±1.27）×10-3mm/s2、（2.20±0.08）×10-3mm/s2、（2.20±0.09）×10-3mm/s2、（2.22±0.07）×10-3mm/s2;The difference was statistically significant（P<0.05）.ADC of simulated CSF/simulated ideal cyst,simulated CSF/simulated slow transit cyst,simulated CSF/simulated rapid transit cyst,with a ratio at b=1000s/mm2Groups were,respectively,1.76±0.09、1.77±0.09、1.76±0.09;At b=100s/mm2Groups were,respectively,13.75±0.68、13.75±0.76、13.65±0.69;The difference was statistically significant（P<0.05）.2、Clinical part:A total of 480 patients were examined,among which one patient was excluded due to unclear scanning images.A total of 479patients were enrolled,including 265 males,214 females,male age（62.12±15.88）and female age（61.26±16.99）.35 patients had enlarged cistern area and 35 patients were included in the arachnoid cyst group,including 30 male and 5 female,male（57.97±15.57）and female（59.60±21.56）.ADC values for arachnoid cyst,anterior bridge pool were at b=1000s/mm2Groups are respectively（3.12±0.19）×10-3mm/s2、（3.73±0.35）×10-3mm/s2;At b=100s/mm2Groups,respectively,（3.29±0.35）×10-3mm/s2、（21.01±3.24）×10-3mm/s2;The difference was statistically significant（P<0.05）.ADC of prebridge pool,arachnoid cysts in the large occipital pool,and the ratio at b=1000s/mm2Group is 1.20±0.15;At b=100s/mm2Groups is 6.41±0.88;For the pairwise comparisons,the difference was statistically significant（P<0.05）.Conclusion（s）:1、Identification of large and arachnoid cysts is not characteristic;the low b DWI sequence can accurately identify arachnoid cysts.2、It is possible to identify large occipital pool and arachnoid cysts by cisternography.The imaging manifestation of contrast filling in the occipital cisterum area may be either large pool or rapid-traffic arachnoid cyst.3、The expansion of the cistern is mostly caused by arachnoid cysts in the occipital,and its formation may be a self-protection mechanism of the human body.4、The incidence of arachnoid cyst is related to gender,and the incidence is higher than that of women. |
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