Preliminary Study In The Diagnosis Of Intracranial Tumors By Using T2 Star Weighted Angiography

Objective:To evaluate the diagnostic value and ability in showing the characters of SWAN(T2 star weighted angiography) for studying the intracranial neoplasms, and estimate the value in preoperative grading of cerebral neuroepithelial tumors by using SWAN sequence.Subjects and methods:34 patients(22 males and 12 females,13-77 years old, mean age51.7±15.1 years) with intracranial neoplasm were included in the study, all were performed T1 weighted imaging(T1WI), contrast enhanced T1 weighted imaging(CET1WI), T2 fluid-attenuated inversion recovery(T2FLAIR), T2* multiple echo recalled gradient echo(T2 MERGE) and T2 star weighted angiography(SWAN) sequence by using GE HDx 3.0T MR Scanner,8 channel coil;22 of them performed contrast enhanced T1-weighted imaging. SWAN images were compared on a slice-by-slice basis with each of the comparison sequences (T1WI, T2* MERGE, T2FLAIR, CET1WI as available per case).The bound, blood and vascular structure, internal structure, edema were subjectively analysed. Each category was assigned a numerical value according to a scale ranging from 0 to 3.0 means sequence could not distinguish the morphological character of tumor,1 means sequence could distinguish the character partially, less than 50%,2 means sequence could distinguish the character partially, more than 50%,3 means sequence could distinguish the character fully.The SWAN images of patients with postoperative pathology proved cerebral neuroepithelial tumors were imported into the workstation(GE ADW 4.3).By using CT images and routine MRI sequences to exclude the calcification, and using the minimum intense project technology to exclude the isolated veins in the neoplasms, the irregular hypointensity areas were regarded as magnetic susceptibility artifact (MSA). We delineated and measured the area of the MSA detected by SWAN every slice by hand, then made quotient with the thickness, finally caculated the total volume(mm3)of every slice in every patient.The rank sum test were implied as the statistical method. First to determine the statistical difference between SWAN and using routine sequences in each character, and then in the group that exists difference, the statistical comparison were made between SWAN and each sequence. The difference of the volume of magnetic susceptibility artifact (MSA) in low and high grading neuroepithelial tumors was compared by the Wilconxon signed rank test.Result:All the 34 patients,17 were cerebral neuroepithelial tumors patients,9 were metastatic tumor patients,4 were meningioma patients,2 were cerebral lymphoma patients,1 was hemangioblastoma and 1 was germinoma. The neuroepithelial tumors were classified, according to the postoperative pathology result,(WHO grade III-IV)were regarded as high-grade neuroepithelial tumors group, while (WHO gradeI-II)were regarded as low-grade neuroepithelial tumors group.7 were low-grade neuroepithelial tumors, while 10 were high-grade neuroepithelial tumors.In showing the blood product in the neoplasms, there is statistical significance among the five sequences, SWAN has better display effect than the other using sequences. In showing the bound of the neoplasms, there is no statistical significance among the five sequences in the display effect. In showing the internal structure of the neoplasms, there is statistical significance among the five sequences. There is no statistical significance between SWAN and CET1WI, SWAN and T2*MERGE in the display effect. SWAN has better display effect than T1WI and T2FLAIR. In showing the edema around the neoplasms, there is statistical significance among the five sequences, T2FLAIR has the best display effect. SWAN has better display effect than Tl WI and CET1WI. There is no statistical significance between SWAN and T2*MERGE.The volume of MSA in the high-grade neuroepithelial tumors(6617.4mm3) was significantly larger than that in the low-grade neuroepithelial tumors(77.8 mm3), which was identified by the Wilconxon signed rank test (P<0.05).Conclusion:1. SWAN can show the blood and vascular structure better than the routine MRI sequence, and it also showed a certain diagnostic value in showing the internal structure, and in bounds and edema around neoplasms, SWAN with 3D acquisition, short imaging time, can reduce the omisson of lesions maximatily, raise the efficiency of examination, it is a supplementary sequence of the routine MR sequence in checking cerebral tumors.2. As a susceptibility-weighted sequence, SWAN can provide important supplementary information for preoperative grading of the cerebral neuroepithelial tumors through the volume of MSA in them.