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문제 정의
- To our knowledge, there have been no previous studies that have compared the diagnostic value of aforementioned advanced MR sequences, including DWI, DSC PWI and SWI. Thus, the purpose of our study was to compare PWI, DWI and SWI for the differentiation of tumor recurrence and delayed RT-related changes in patients treated with RT for primary brain tumors.
제안 방법
- In all the patients, follow up MRI studies were performed with one of two 3 T MR imaging scanners (n = 2 [true recurrence = 1 and RT-related changes = 1]; Signa Excite; GE Medical Systems, Milwaukee, WI, USA; and n = 22 [true recurrence = 13 and RT-related changes = 9]; Verio; Siemens MedicalSolutions, Erlangen, Germany) with an eight-channel head coil.
- DWI was performed with a single-shot spin-echo echo-planar imaging sequence on the axial plane before the injection of contrast material with a TR/TE of 6900-10000/55-70 ms at b = 0 and 1000 sec/mm2, 35-38 sections, a 3-mm section thickness, a 1-mm intersection gap, an FOV of 240 × 240 mm, a matrix of 160 × 160, three signal averages, and a voxel resolution of 1.5 × 1.5 × 3 mm.
- The imaging protocol included spin-echo (SE) T1- weighted images (T1WI), fast SE (FSE) T2-weighted images (T2WI), fluid-attenuated inversion recovery (FLAIR) images, echo-planar DWI, SWI, DSC PWI with gadobutrol (Gadovist, Bayer Schering Pharma, Berlin, Germany), and subsequent contrast-enhanced (CE) SE T1WI. The MRI parameters were as follows-: 558-650/8-20 ms/70-90o/384 × 192-212 (TR/TE/ FA/matrix) for SE T1WI; 4500-5160/91-106.
- The MRI data for the conventional MR images, the ADC maps and the DSC PWI were digitally transferred from the Picture Archiving and Communication System (PACS) workstation to a personal computer for further analyses. Relative CBVs (rCBVs) were obtained by using a dedicated software package (nordicICE; NordicImagingLab, Bergen, Norway), with an established tracer kinetic model applied to the first-pass data (22, 23).
- The readers determined the ROIs by drawing the connecting dotted lines with nordicICE software in consensus that contained the entire enhancing lesion of contrast-enhanced T1W image on every continuous sections of the co-registered images. Any areas of gross hemorrhage, small vessels, and necrosis were identified and carefully excluded from the ROIs.
- 2). Then, the volume of dark signal intensity portions of the ROIs were divided by the total volume of the enhancing lesion, which was derived from the summation of ROIs on CE T1W image, to calculate ultimately the proportion of dark signal intensity of the lesions on SW images (proSWI).
- Coregistrations between the CE T1W images and the normalized CBV (nCBV) maps and between the CE T1W images and the ADC maps were performed based on geometric information stored in the respective data sets, by using a dedicated software package (nordicICE; NordicImagingLab, Bergen, Norway).
- In this study, we compared the diagnostic value of three different MRI parameters for the differentiation of newly appearing enhancing lesions in patients who had RT for their primary brain tumors. We found nCBV to be significantly higher and proSWI to be significantly lower within contrast-enhanced regions of true recurrence compared with these parameters in patients with RT-related changes.
대상 데이터
- True recurrence. A 57-year-old woman who underwent gross total resection and concomitant chemoradiotherapy (CCRT) with temozolomide for glioblastoma in the left parietal lobe.
- Radiation therapy (RT)-related change. A 44-year-old woman who underwent gross total resection and concomitant chemoradiotherapy (CCRT) for anaplastic oligoastrocytoma in bilateral frontal lobes.
- In addition to the intrinsic limitations of any retrospective study, there were some noteworthy limitations of our study. First, this study included a small number of patients. However, the two groups from our study population were statistically well balanced in terms of patient numbers, sex ratio, radiation dose, and post-irradiation time (Table 1).
데이터처리
- Clinical characteristics were compared between the true recurrence and RT-related change groups using Student’s unpaired t-test.
- * The difference between the two groups was evaluated by using Student’s unpaired t-test.
- †The difference between the two groups was evaluated by using Student’s unpaired t-test.
- To compare the values of ADC, nCBV, and proSWI between the true recurrence and RT-related change groups, Student’s unpaired t-test was applied.
이론/모형
- Coregistrations between the CE T1W images and the normalized CBV (nCBV) maps and between the CE T1W images and the ADC maps were performed based on geometric information stored in the respective data sets, by using a dedicated software package (nordicICE; NordicImagingLab, Bergen, Norway). The differences in slice thickness between images were corrected automatically by the re-slicing and coregistration method, which was based on underlying images and structural images. The nCBV maps and ADC maps were displayed as color overlays on the CE T1W images (Fig.
성능/효과
- We excluded 45 patients for the following reasons: (a) inadequate MR imaging; (b) no newly appearing lesions on follow-up MR images; (c) newly developed lesions less than one year after the completion of RT; and (d) loss to follow-up. As a result, a total of 24 patients (15 men, 9 women; mean age, 46.3 years old; range, 26-66 years), consisting of 10 patients with glioblastoma, 4 patients with anaplastic astrocytoma, 3 patients with anaplastic oligodendroglioma, 2 patients with anaplastic oligoastrocytoma, and 5 other patients with miscellaneous tumors, including gliosarcoma (n = 1), primitive neuroectodermal tumor (n = 1), oligodendroglioma (n = 1), pilocytic astrocytoma (n = 1), and ependymoma (n = 1), were included and identified to have true recurrence (n = 14) or delayed RT-related changes (n = 10) by either radiologic conclusion or histological confirmation after the surgery (Fig. 1).
- Among the 24 patients enrolled in the study, 14 patients were finally concluded to have true recurrences (histologic confirmation = 11, radiologic conclusion = 3), and 10 patients were concluded to have RT-related changes (histologic confirmation = 2, radiologic conclusion = 8). The mean time from the completion of RT to new enhancing lesions on MRI was 1216.
- The mean nCBV value was higher in the true recurrence group than in the RT-related change group, and the difference was statistically significant (2.64 vs. 1.06; P = .004). The RT-related change group showed a higher mean proSWI than the recurrence group (43.
- We found that the proSWI from the calculation of SWI quantitative data was the most promising parameter for differentiating the tumor recurrence from delayed RT-related changes. With ROC analysis, the sensitivity, specificity, and accuracy for the detection of tumor recurrence with the proSWI were 78.6% (11 of 14), 100% (10 of 10), and 87.5% (21 of 24), respectively. Regardless of the pathologic types of primary brain tumors, RT-related change lesions showed significantly larger amount of hemorrhagic foci on SWI, compared to tumor recurrence and the most powerful method for the detection of hemorrhage was SWI.
- In conclusion, we found that the true recurrence group showed higher nCBV values and significantly lower proSWI values than the RT-related change group. The results of our study suggest that the proSWI is the most promising parameter for the differentiation of the newly developed enhancing lesions more than one year after RT completion in primary brain tumor patients.
- In conclusion, we found that the true recurrence group showed higher nCBV values and significantly lower proSWI values than the RT-related change group. The results of our study suggest that the proSWI is the most promising parameter for the differentiation of the newly developed enhancing lesions more than one year after RT completion in primary brain tumor patients. With SWI, we can make earlier decisions for newly enhancing lesions after brain RT and provide the suitable treatment plans to related clinicians, thus improving patients’ overall prognoses and quality of life.
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