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BACKGROUND AND PURPOSE: MR imaging can reflect the pathologic progression of carcinoma ex pleomorphic adenoma (CXPA). This study aimed to identify the imaging findings related to extracapsular invasion of CXPA. Additionally, the pathologic background of these findings was investigated. MATERIALS AND METHODS:This retrospective study included 37 patients with histologically confirmed CXPA. Three radiologists independently evaluated whether the CXPA showed the following characteristic MR imaging findings: border, capsule, the corona sign on fat-saturated T2WI and contrast-enhanced fat-saturated T1WI, and the black ring sign. The corona sign appeared larger on fat-saturated and/or contrast-enhanced fat-saturated T1WI than on T1WI. The black ring sign was defined as an intratumoral nodule with a thick lowintensity rim on T2WI. Interreader agreement of the visual assessment was performed using k analysis, and MR imaging and histopathologic findings were also correlated. Kaplan-Meier survival and the log-rank test were used to estimate the 3-year disease-free survival.RESULTS: MR imaging findings, especially peritumoral findings, showed a significant difference between invasive and noninvasive CXPA. The reliability was poor for the border and capsule. In contrast, it was good for the corona sign on fat-saturated and contrastenhanced fat-saturated T1WI and the black ring sign. Pathologically, the corona sign reflected the invasiveness of the tumor and inflammatory cells, while the black ring sign reflected hyalinization or fibrosis. The corona sign also showed a significant difference in the 3-year disease-free survival.CONCLUSIONS: MR imaging findings, including the corona and black ring signs, reliably differentiated invasive and noninvasive CXPA. The corona sign can be used as a prognostic factor for CXPA.ABBREVIATIONS: CE ¼ contrast-enhanced; CXPA ¼ carcinoma ex pleomorphic adenoma; FS ¼ fat-saturated; PA ¼ pleomorphic adenoma C arcinoma ex pleomorphic adenoma (CXPA) arises from a pre-existing pleomorphic adenoma (PA). It is more likely to occur in cases of PA with multiple recurrences or requiring longterm follow-ups. CXPA comprises 3.6% and 11.6% of all salivary gland tumors and malignancies, respectively, and is most often found in the parotid gland. 1,2 Carcinoma in PA develops in the luminal cells of the tubular structures, and the malignant cells then destroy the pre-existing PA

A 77-year-old man presented with an incidental finding of right renal artery aneurysm without symptoms. Computed tomography revealed a 22 mm saccular aneurysm with a wide neck at the main renal artery trunk. An 8 × 100 mm Viabahn stent graft (W. L. Gore, Flagstaff, AZ) was deployed by fully pulling back the guiding sheath. However, the deployment knob was not able to be pulled. We returned the guiding sheath to the original position and confirmed the cause was the bowstring phenomenon. Because avoidance of this phenomenon required straightening of the tortuous vessel, the stent graft was deployed by short pull-back of the guiding sheath. Computed tomography after a year revealed no opacification of the aneurysm and the patency of the stent graft.

A 61-year-old man presented with retroperitoneal hemorrhage caused by an aneurysm rupture of the pancreaticoduodenal arcade (PDA), and acute celiac artery dissection distal to celiac axis stenosis. Owing to the gradual growth of the false lumen, we planned to deploy a stent to the celiac artery dissection and embolize the PDA aneurysm. Prior to stent placement, we assessed the acute celiac artery dissection distal to the stenosis using four-dimensional computed tomography (CT) angiography through expiration/inspiration/expiration cycle. We diagnosed median arcuate ligament syndrome considering that the celiac axis showed a hooked narrowing at end-expiration, and the compression decreased at end-inspiration. Additionally, the true lumen distal to the stretched axis dilated in the inspiration phase. Therefore, we could advance a catheter into the true lumen during inspiration and successfully deploy a stent. Subsequently, laparoscopic median arcuate ligament release was performed after the stent deployment. A postoperative CT scan showed good patency in the stent, with disappearance of the blood filling the false lumen and with reduced celiac axis stenosis.