Deep Learning for MR Angiography: Automated Detection of Cerebral Aneurysms.

Purpose To develop and evaluate a supportive algorithm using deep learning for detecting cerebral aneurysms at time-of-flight MR angiography to provide a second assessment of images already interpreted by radiologists. Materials and Methods MR images reported by radiologists to contain aneurysms were extracted from four institutions for the period from November 2006 through October 2017. The images were divided into three data sets: training data set, internal test data set, and external test data set. The algorithm was constructed by deep learning with the training data set, and its sensitivity to detect aneurysms in the test data sets was evaluated. To find aneurysms that had been overlooked in the initial reports, two radiologists independently performed a blinded interpretation of aneurysm candidates detected by the algorithm. When there was disagreement, the final diagnosis was made in consensus. The number of newly detected aneurysms was also evaluated. Results The training data set, which provided training and validation data, included 748 aneurysms (mean size, 3.1 mm ± 2.0 [standard deviation]) from 683 examinations; 318 of these examinations were on male patients (mean age, 63 years ± 13) and 365 were on female patients (mean age, 64 years ± 13). Test data were provided by the internal test data set (649 aneurysms [mean size, 4.1 mm ± 3.2] in 521 examinations, including 177 male patients and 344 female patients with mean age of 66 years ± 12 and 67 years ± 13, respectively) and the external test data set (80 aneurysms [mean size, 4.1 mm ± 2.1] in 67 examinations, including 19 male patients and 48 female patients with mean age of 63 years ± 12 and 68 years ± 12, respectively). The sensitivity was 91% (592 of 649) and 93% (74 of 80) for the internal and external test data sets, respectively. The algorithm improved aneurysm detection in the internal and external test data sets by 4.8% (31 of 649) and 13% (10 of 80), respectively, compared with the initial reports. Conclusion A deep learning algorithm detected cerebral aneurysms in radiologic reports with high sensitivity and improved aneurysm detection compared with the initial reports. © RSNA, 2018 See also the editorial by Flanders in this issue.

Internal Hernias in the Era of Multidetector CT: Correlation of Imaging and Surgical Findings.

Clinical diagnosis of internal hernias is challenging because of their nonspecific signs and symptoms. Many types of internal hernias have been defined: paraduodenal, small bowel mesentery-related, greater omentum-related, lesser sac, transverse mesocolon-related, pericecal, sigmoid mesocolon-related, falciform ligament, pelvic internal, and Roux-en-Y anastomosis-related. An internal hernia is a surgical emergency that can develop into intestinal strangulation and ischemia. Accurate preoperative diagnosis is crucial for appropriate management. Multidetector computed tomography (CT), with its thin-section axial images, high-quality multiplanar reformations, and three-dimensional images, currently plays an essential role in preoperative diagnosis of internal hernias. The diagnostic approach to internal hernias at multidetector CT includes detecting an intestinal closed loop, identifying the hernia orifice, and analyzing abnormal displacement of surrounding structures and key vessels around the hernia orifice and hernia sac. At each step, multidetector CT can depict pathognomonic findings. A saclike appearance suggests an intestinal closed loop in several types of internal hernias. Convergence, engorgement, and twisting of mesenteric vessels in the hernia orifice can be seen clearly at multidetector CT, especially with use of multiplanar reformations. For definitive diagnosis of an internal hernia, analysis of displacement of anatomic landmarks around the hernia orifice is particularly important, and thin-section images provide the required information. Detailed knowledge of the anatomy, etiology, and imaging landmarks of the various hernia types is also necessary. Familiarity with the appearances of internal hernias at multidetector CT allows accurate and specific preoperative diagnosis. (©)RSNA, 2015.

Correlation between Phase-difference-enhanced MR Imaging and Amyloid Positron Emission Tomography: A Study on Alzheimer's Disease Patients and Normal Controls.

PURPOSE: While amyloid-ß deposition in the cerebral cortex for Alzheimer's disease (AD) is often evaluated by amyloid positron emission tomography (PET), amyloid-ß-related iron can be detected using phase difference enhanced (PADRE) imaging; however, no study has validated the association between PADRE imaging and amyloid PET. This study investigated whether the degree of hypointense areas on PADRE imaging correlated with the uptake of amyloid PET. METHODS: PADRE imaging and amyloid PET were performed in 8 patients with AD and 10 age-matched normal controls. ROIs in the cuneus, precuneus, superior frontal gyrus (SFG), and superior temporal gyrus (STG) were automatically segmented. The degree of hypointense areas on PADRE imaging in each ROI was evaluated using 4-point scaling of visual assessment or volumetric semiquantitative assessment (the percentage of hypointense volume within each ROI). The mean standardized uptake value ratio (SUVR) of amyloid PET in each ROI was also calculated. The Spearman's correlation coefficient between the 4-point scale of PADRE imaging and SUVR of amyloid PET or between the semiquantitative hypointense volume percentage and SUVR in each ROI was evaluated. RESULTS: In the precuneus, a significant positive correlation was identified between the 4-point scale of PADRE imaging and SUVR of amyloid PET (Rs = 0.5; P = 0.034) in all subjects. In the cuneus, a significant positive correlation was identified between the semiquantitative volume percentage of PADRE imaging and SUVR of amyloid PET (Rs = 0.55; P = 0.02) in all subjects. CONCLUSION: Amyloid-ß-enhancing PADRE imaging can be used to predict the SUVR of amyloid PET, especially in the cuneus and precuneus, and may have the potential to be used for diagnosing AD by detecting amyloid deposition.

Ectopic clival craniopharyngioma with intratumoral hemorrhage: A case report.

Craniopharyngiomas located outside the intra/suprasellar region are rare and the incidence of intratumoral hemorrhage is also rare. A 45-year-old woman with visual field defect underwent subtotal resection of the tumor located in the skull base. CT revealed a well-defined mass with calcifications involving the clivus, and MRI showed anterior displacement of a normal pituitary gland by the mass consisting cystic portions with some fluid-fluid levels and enhancing solid portions. Surgery and histopathological examination revealed an ectopic adamantinomatous craniopharyngioma arising from the clivus with intratumoral hemorrhage. Though this condition is rare, detailed analysis of symptoms in association with imaging findings should alert the physician to the possibility of craniopharyngiomas.

Posterior fossa choroid plexus papilloma with focal ependymal differentiation in an adult patient: A case report and literature review.

Choroid plexus papillomas (CPPs) are rare neoplasms classified as World Health Organization grade I tumors. CPPs containing other tissues have occasionally been documented in the literature. However, few of these previous reports have provided clinical and radiological information. We herein report a case of a posterior fossa CPP with focal ependymal differentiation in a 42-year-old woman who presented with a 6-month history of progressive headache. Preoperative radiological images showed a hypervascular tumor protruding into the left foramen of Luschka with perilesional edema. Gross total resection of the tumor was performed. Histopathological examination revealed that the tumor was composed of papillary structures. Immunohistochemical staining of glial fibrillary acidic protein was focally positive around the capillaries, which was suggestive of "perivascular pseudorosette" formation. Our case showed similar imaging appearances as those of CPP; thus, it seems difficult to distinguish CPP with versus without ependymal differentiation by clinical and radiological features alone. The clinical significance and pathogenesis of ependymal differentiation in CPP remain unclear, and further case reports are required.

Imaging features of benign mass lesions in the nasal cavity and paranasal sinuses according to the 2017 WHO classification.

The World Health Organization (WHO) 2017 classification of head and neck tumors has been just published and has reorganized tumors of the nasal cavity and paranasal sinuses. In this classification, three new entities (seromucinous hamartoma, NUT carcinoma, and biphenotypic sinonasal sarcoma) were included, while the total number of tumors has been reduced by excluding tumors if they did not occur exclusively or predominantly in this region. Among these entities, benign tumors were classified as sinonasal papillomas, respiratory epithelial lesions, salivary gland tumors, benign soft tissue tumors, or other tumors. In contrast, inflammatory diseases often show tumor-like appearances. The imaging features of these benign tumors and tumor-like inflammatory diseases often resemble malignant tumors, and some benign lesions should be given attention in the follow-up period and before surgery to avoid recurrence, malignant transformation, or massive bleeding. Understanding the CT and MR imaging features of various benign mass lesions is clinically important for appropriate therapy. The purpose of this article is to describe the clinical characteristics and imaging features of each of clinically important nasal and paranasal benign mass lesions, as classified according to the WHO 2017 classification of head and neck tumors, along with some inflammatory diseases.

Differentiation of Brain Metastases and Gliomas Based on Color Map of Phase Difference Enhanced Imaging.

Background and objective: Phase difference enhanced imaging (PADRE), a new phase-related MRI technique, can enhance both paramagnetic and diamagnetic substances, and select which phases to be enhanced. Utilizing these characteristics, we developed color map of PADRE (Color PADRE), which enables simultaneous visualization of myelin-rich structures and veins. Our aim was to determine whether Color PADRE is sufficient to delineate the characteristics of non-gadolinium-enhancing T2-hyperintense regions related with metastatic tumors (MTs), diffuse astrocytomas (DAs) and glioblastomas (GBs), and whether it can contribute to the differentiation of MTs from GBs. Methods: Color PADRE images of 11 patients with MTs, nine with DAs and 17 with GBs were created by combining tissue-enhanced, vessel-enhanced and magnitude images of PADRE, and then retrospectively reviewed. First, predominant visibility of superficial white matter and deep medullary veins within non-gadolinium-enhancing T2-hyperintense regions were compared among the three groups. Then, the discriminatory power to differentiate MTs from GBs was assessed using receiver operating characteristic analysis. Results: The degree of visibility of superficial white matter was significantly better in MTs than in GBs (p = 0.017), better in GBs than in DAs (p = 0.014), and better in MTs than in DAs (p = 0.0021). On the contrary, the difference in the visibility of deep medullary veins was not significant (p = 0.065). The area under the receiver operating characteristic curve to discriminate MTs from GBs was 0.76 with a sensitivity of 80% and specificity of 64%. Conclusion: Visibility of superficial white matter on Color PADRE reflects inferred differences in the proportion of vasogenic edema and tumoral infiltration within non-gadolinium-enhancing T2-hyperintense regions of MTs, DAs and GBs. Evaluation of peritumoral areas on Color PADRE can help to distinguish MTs from GBs.

In vitro Study of Serial Changes to Carmustine Wafers (Gliadel) with MR Imaging and Computed Tomography.

PURPOSE: Implantation of carmustine wafers (Gliadel) in vivo is accompanied by characteristic serial changes on MRI and CT, such as transient hyperintensity of the wafers on T1-weighted images (T1WIs) and considerable gas accumulation in surgical resection cavities. The purpose of this study was to evaluate intrinsic imaging changes to carmustine wafers in vitro. METHODS: Three phantoms simulating a surgical resection cavity were constructed. Each contained either a carmustine wafer fixed with oxidized regenerated cellulose and fibrin sealant, an unfixed carmustine wafer, or a fixed polyethylene control disk, immersed in phosphate-buffered saline. Image acquisition of the phantoms was performed on MRI and CT until 182 days after construction. The radiological appearances of the object in each phantom were assessed by visual evaluation and quantification of the region of interest. The volume of gas around the objects at 24 h after constructing the phantoms was also measured. RESULTS: The carmustine wafers showed low signal intensities on T1WIs and T2-weighted images (T2WIs), and high densities on CT images at 24 h. The signal intensities and CT densities gradually approximated those of saline over a period of months. However, the carmustine wafers never showed hyperintensity on T1WIs in vitro. The fixed carmustine wafer showed slower radiological changes, as compared to the unfixed wafer. The gas volume around the fixed carmustine wafer was greater than that around the fixed control disk. CONCLUSION: Changes to the carmustine wafers probably reflected penetration of fluid inside and degradation of the hydrophobic matrix. Reported transient hyperintensity of wafers on T1WIs in vivo is regarded as the result of biological reactions, whereas the initial production of gas is considered as an intrinsic characteristic of wafers.

Serum KL-6 level as an indicator of active or inactive interstitial pneumonitis associated with connective tissue diseases.

OBJECTIVE: To elucidate the cut off levels of serum KL-6 indicating patients with interstitial pneumonitis (IP) and patients with active IP associated with connective tissue diseases (CTDs). METHODS: CTD patients whose serum KL-6 level was measured were included. IP was diagnosed on the basis of medical records including XP/CT findings, and active IP was assumed in case that intervention for IP was newly added. The cut off levels were determined by receiver operating characteristic (ROC) curve analysis. RESULTS: Among 240 (174 females) patients, 67 (42) had IP and 15 (9) had active IP. The ages of patients with and without IP, and with active IP and with inactive IP were 70.3±9.5 and 62.8±15.3, and 72.8±8.1 and 69.6±9.8, respectively. IP was significantly more prevalent in males and the elderly. The KL-6 levels were 990±90 and 301±12 U/mL in patients with and without IP, and 1,905±236 and 726±54 U/mL in those with active IP and with inactive IP, respectively. ROC curve analysis showed a cut off level of 509 U/mL for indicating IP, and that of 1,051-1,060 U/mL for indicating active IP. CONCLUSION: A serum KL-6 level of higher than 500 U/mL is a marker of the presence of IP, and a level of higher than 1,000 U/mL is a marker of the presence of active IP associated with CTDs.