ABSTRACT
Objective:To investigate the value of MR subtraction images in improving the interobserver agreement for Bosniak Ⅱ, ⅡF, and Ⅲ cystic renal masses (CRMs) with Bosniak classification version 2019.Methods:From January 2009 to August 2020, 323 patients (335 CRMs) with surgical pathology results and complete preoperative MRI examination (T 2WI, T 1WI precontrast images and enhanced MRI in corticomedullary, nephrographic, and excretory phases) were retrospectively collected in the First Medical Center of PLA General Hospital. The CRMs of Bosniak Ⅱ, ⅡF, and Ⅲ were selected and classified by 2 experienced genitourinary radiologists according to the Bosniak classification version 2019. The "Subtraction" function in the American GE ADW 4.4 workstation was used to perform subtraction images reconstruction on the enhanced images in the corticomedullary, nephrographic, and excretory phases. Blinded to pathologic information, the other 2 radiologists independently classified the enrolled CRM cases with and without subtraction MR images, respectively, with an interval of 1 month. Ultimately, by using weighted Kappa value, interobserver agreement was evaluated, and the differences in weighted Kappa value were compared using the Gwet coefficient. Results:A total of 187 patients with 187 CRMs were enrolled in the study. The results of the classification of Bosniak Ⅱ, ⅡF, and Ⅲ CRMs categorized by 2 radiologists without and with subtraction images showed that 119 and 141 cases were consistent, and 68 and 46 were inconsistent, respectively. The weighted Kappa value for interobserver agreement among two radiologists without and with subtraction MR images was 0.60 (95%CI 0.53-0.68) and 0.73 (95%CI 0.66-0.80), respectively. The interobserver agreement was higher with subtraction images than that without subtraction images ( t=-2.56, P=0.011). Conclusion:According to the MRI criteria of Bosniak classification version 2019, the interobserver agreement for Bosniak Ⅱ, ⅡF, and Ⅲ CRMs could be improved using subtraction MR images, which may facilitate the popularization and application of Bosniak classification version 2019.
ABSTRACT
PURPOSE: To determine the added value of dynamic subtraction magnetic resonance (MR) imaging for the localization of prostate cancer. MATERIALS AND METHODS: We examined 21 consecutive patients who underwent MR imaging in 3T unit with a phased-array body coil and then had radical prostatectomy. After T2-weighted fast spin-echo imaging, we performed a contrast-enhanced dynamic 3D gradient-echo imaging consisting of pre-contrast, 2 successive early-phased (first imaging was started just after the appearance of contrast material in the aortic bifurcation followed by second imaging 35 seconds after the initiation of first imaging) and one 5-minute delayed post-contrast series. Subtraction of pre-contrast images from corresponding post-contrast images of each phase was performed on the console. RESULTS: On ROC analysis, the overall accuracy (Az value) of dynamic imaging combined with subtraction imaging was higher than T2-weighted imaging (p = 0.001) or conventional dynamic imaging alone (p = 0.074) for localization of cancer foci regardless of their zonal locations. Among pathologically verified 81 lesions, the mean volume of detected lesions with the subtraction images (n = 49, 0.69cm3) was smaller than with T2-weighted images (n = 14, 1.05cm3) or conventional dynamic images (n = 43, 0.71cm(3)). CONCLUSION: For localization of small prostate cancer, additional subtraction for the dynamic imaging could be superior to both T2-weighted imaging and un-subtracted dynamic imaging.