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Accurate assessment of nodal metastasis in head and neck squamous cell carcinoma (SCC) is important, and diffusion-weighted imaging (DWI) has emerged as a potential technique in differentiating benign from malignant lymph nodes (LNs). This study aims to evaluate the diagnostic performance of texture analysis using apparent diffusion coefficient (ADC) data of multi-shot echo-planar imaging-based DWI (msEPI-DWI) in predicting metastatic LNs of head and neck SCC. 36 patients with pathologically proven head and neck SCC were included in this study. A total of 204 MRI-detected LNs, including 176 subcentimeter-sized LNs, were assigned to metastatic or benign groups. Texture features of LNs were compared using independent t-test. Hierarchical cluster analysis was performed to exclude redundant features. Multivariate logistic regression and receiver operating characteristic analysis were performed to assess the diagnostic performance. The discriminative texture features for predicting metastatic LNs were complexity, energy and roundness. Areas under the curves (AUCs) for diagnosing metastasis in all/subcentimeter-sized LNs were 0.829/0.767 using complexity, 0.699/0.685 using energy and 0.671/0.638 using roundness, respectively. The combination of three features resulted in higher AUC values of 0.836/0.781. In conclusion, texture analysis of ADC data using msEPI-DWI could be a useful tool for nodal staging in head and neck SCC. [ABSTRACT FROM AUTHOR]

Background and Objectives: We aimed to identify prognostic computed tomography (CT) findings in retrofenestral otosclerosis, with particular attention paid to the role of otosclerotic lesion area in predicting post-stapedotomy outcome. Materials and Methods: We included 17 subjects (23 ears) with retrofenestral otosclerosis who underwent stapedotomy. On preoperative CT, the presence of cavitating lesion and involvement of various subsites (cochlea, round window [RW], vestibule, and semicircular canal) were assessed. Pre- and post-stapedotomy audiometric results were compared according to the CT findings. The surgical outcomes were analyzed using logistic regression with Firth correction. Results: Cavitating lesions were present in 15 of 23 ears (65.2%). Involvement of the RW was the strongest predictor of unsuccessful surgical outcome, followed by involvement of the internal auditory canal (IAC) and the cochlea. Conclusions: RW and IAC involvement in retrofenestral otosclerosis were shown to predict unsuccessful outcomes. While a "third window" effect caused by extension of a cavitating lesion into the IAC may dissipate sound energy and thus serve as a barrier to desirable postoperative audiological outcome, a "single window" effect due to an extension of retrofenestral otosclerosis into the RW may preclude a good surgical outcome, even after successful stapedotomy, due to less compressible cochlear fluid and thus decreased linear movement of the piston. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the diagnostic accuracies of ultrasound (US) and 18-F-FDG positron emission tomography (PET) or PET/computed tomography (CT) for detecting recurrent papillary thyroid carcinoma (PTC) after total thyroidectomy. Our study enrolled 76 postoperative patients who underwent both neck US and PET because of the suspicion of recurrence. The results of US and PET were correlated with the histopathology, the radioactive iodine whole body scan (WBS) or the clinical follow-up results. Among them, 53 patients had recurrent disease (local recurrence, 42; distant metastasis, 3; elevated Tg level, 8) and 23 showed no evidence of disease. From the analysis, US showed higher diagnostic accuracy, sensitivity and specificity compared with those of PET (71.1%, 71.7% and 69.6% vs. 55.3%, 56.6%, and 52.2%). PET added diagnostic information in a limited number of patients with negative results on neck US (3 with neck recurrence and 2 with distant metastasis). [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a movement disorder that develops due to degenerative loss of dopaminergic cells in the substantia nigra of the midbrain. Recent advances in MRI techniques have demonstrated various imaging findings that can reflect the underlying pathophysiological processes occurring in Parkinson's disease. Many imaging studies have shown that such findings can assist in the diagnosis of Parkinson's disease and its differentiation from atypical parkinsonism. In this review, we present MRI techniques that can be used in clinical assessment, such as nigrosome imaging and neuromelanin imaging, and we provide the detailed imaging features of Parkinson's disease reflecting nigrostriatal degeneration., Competing Interests: Author Contributions: Conceptualization, K.J., B.Y.J., C.B.S.methodology, B.Y.J.resources, K.J., B.Y.J., S.Y.S., N.Y., C.S.J., K.J.H.software, K.J., B.Y.J., S.Y.S., N.Y.supervision, K.J., B.Y.J., C.B.S., S.Y.S., K.J.H., K.S.E.validation, K.J., C.B.S., S.Y.S., N.Y., C.S.J., K.J.H.visualization, K.J., B.Y.J., C.B.S., S.Y.S., N.Y., K.S.E.writing—original draft, K.J., B.Y.J., C.B.S.writing—review & editing, all authors. Conflicts of Interest: The authors have no potential conflicts of interest to disclose., (Copyrights © 2022 The Korean Society of Radiology.)

Background: The T2-fluid-attenuated inversion recovery (FLAIR) mismatch sign, has been considered a highly specific imaging biomarker of IDH-mutant, 1p/19q noncodeleted low-grade glioma. This systematic review and meta-analysis aimed to evaluate the diagnostic performance of T2-FLAIR mismatch sign for prediction of a patient with IDH-mutant, 1p/19q noncodeleted low-grade glioma, and identify the causes responsible for the heterogeneity across the included studies., Methods: A systematic literature search in the Ovid-MEDLINE and EMBASE databases was performed for studies reporting the relevant topic before November 17, 2020. The pooled sensitivity and specificity values with their 95% confidence intervals were calculated using bivariate random-effects modeling. Meta-regression analyses were also performed to determine factors influencing heterogeneity., Results: For all the 10 included cohorts from 8 studies, the pooled sensitivity was 40% (95% confidence interval [CI] 28-53%), and the pooled specificity was 100% (95% CI 95-100%). In the hierarchic summary receiver operating characteristic curve, the difference between the 95% confidence and prediction regions was relatively large, indicating heterogeneity among the studies. Higgins I 2 statistics demonstrated considerable heterogeneity in sensitivity (I 2 = 83.5%) and considerable heterogeneity in specificity (I 2 = 95.83%). Among the potential covariates, it seemed that none of factors was significantly associated with study heterogeneity in the joint model. However, the specificity was increased in studies with all the factors based on the differences in the composition of the detailed tumors., Conclusions: The T2-FLAIR mismatch sign is near-perfect specific marker of IDH mutation and 1p/19q noncodeletion., (© The Author(s) 2022. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)

Purpose: Preoperative MRI detection of post-laminar optic nerve invasion (PLONI) offers guidance in assessing the probability of total tumor resection, an estimation of the extent of surgery, and screening of candidates for eye-preserving therapies or neoadjuvant chemotherapies in the patients with retinoblastoma (RB). The purpose of this systematic review and meta-analysis was to evaluate the diagnostic performance of MRI for detecting PLONI in patients with RB and to demonstrate the factors that may influence the diagnostic performance., Methods: Ovid-MEDLINE and EMBASE databases were searched up to January 11, 2020, for studies identifying the diagnostic performance of MRI for detecting PLONI in patients with RB. The pooled sensitivity and specificity of all studies were calculated followed by meta-regression analysis., Results: Twelve (1240 patients, 1255 enucleated globes) studies were included. The pooled sensitivity was 61%, and the pooled specificity was 88%. Higgins I 2 statistic demonstrated moderate heterogeneity in the sensitivity (I 2  = 72.23%) and specificity (I 2  = 78.11%). Spearman correlation coefficient indicated the presence of a threshold effect. In the meta-regression, higher magnetic field strength (3 T than 1.5 T), performing fat suppression, and thinner slice thickness (< 3 mm) were factors causing heterogeneity and enhancing diagnostic power across the included studies., Conclusions: MR imaging was demonstrated to have acceptable diagnostic performance in detecting PLONI in patients with RB. The variation in the magnetic field strength and protocols was the main factor behind the heterogeneity across the included studies. Therefore, there is room for developing and optimizing the MR protocols for patients with RB.

Objective: To determine the diagnostic performance of neuromelanin-sensitive magnetic resonance imaging discriminating between patients with Parkinson's disease and normal healthy controls and to identify factors causing heterogeneity influencing the diagnostic performance., Methods: A systematic literature search in the Ovid-MEDLINE and EMBASE databases was performed for studies reporting the relevant topic before February 17, 2020. The pooled sensitivity and specificity values with their 95% confidence intervals were calculated using bivariate random-effects modeling. Subgroup and meta-regression analyses were also performed to determine factors influencing heterogeneity., Results: Twelve articles including 403 patients with Parkinson's disease and 298 control participants were included in this systematic review and meta-analysis. Neuromelanin-sensitive magnetic resonance imaging showed a pooled sensitivity of 89% (95% confidence interval, 86-92%) and a pooled specificity of 83% (95% confidence interval, 76-88%). In the subgroup and meta-regression analysis, a disease duration longer than 5 and 10 years, comparisons using measured volumes instead of signal intensities, a slice thickness in terms of magnetic resonance imaging parameters of more than 2 mm, and semi-/automated segmentation methods instead of manual segmentation improved the diagnostic performance., Conclusion: Neuromelanin-sensitive magnetic resonance imaging had a favorable diagnostic performance in discriminating patients with Parkinson's disease from healthy controls. To improve diagnostic accuracy, further investigations directly comparing these heterogeneity-affecting factors and optimizing these parameters are necessary., Key Points: • Neuromelanin-sensitive MRI favorably discriminates patients with Parkinson's disease from healthy controls. • Disease duration, parameters used for comparison, magnetic resonance imaging slice thickness, and segmentation methods affected heterogeneity across the studies.

Amide proton transfer-weighted magnetic resonance imaging (APTw-MRI), which is effective in tumor characterization, has expanded its role in the head and neck. We aimed to evaluate the diagnostic ability of APTw-MRI in differentiating malignant from benign major salivary gland tumors compared with diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE)-MRI. Between December 2017 and November 2018, 38 subjects, who were diagnosed with major salivary gland tumors and who underwent preoperative 3 T MRI, including APTw-MRI, DWI, and DCE-MRI, were included in this retrospective study. Twenty-three subjects had benign tumors, and fifteen had malignancies. APTw-signals of the tumors were measured and compared according to the histopathological diagnosis. Using receiver operating characteristic curve analysis, diagnostic performance of APTw-MRI was evaluated and compared with DWI and DCE-MRI using DeLong test. The maximum, mean, and median APTw-signals were significantly higher in malignant than in benign tumors (P < 0.001). The mean and maximum APTw-signals showed excellent area under the curve for predicting malignant tumors (0.948 and 0.939), which were significantly higher than the combining use of DWI and DCE-MRI (0.780) (P = 0.021 and 0.028). Therefore, APTw-MRI could be a useful tool for differentiating malignant from benign major salivary gland tumors, and can be applicable in the clinical setting.

Objective: To investigate the effects of cavitating lesions involving the internal auditory canal (IAC) in subjects with cochlear otosclerosis with regard to poststapedotomy hearing outcome., Study Design: Retrospective study., Setting: Tertiary referral center., Patients: A retrospective chart review of 134 subjects with otosclerosis treated from January 2011 to June 2017 at Seoul National University Bundang Hospital was conducted. Sixteen subjects (23 ears) with temporal bone computed tomography (TBCT)-confirmed cochlear otosclerosis who underwent stapedotomy were included in the study., Main Outcome Measures: Pure tone audiometry (PTA) (i.e., air and bone conduction; AC and BC, respectively) thresholds and air-bone gap (ABG), measured at 6 months postoperatively were compared between cochlear otosclerosis with and without IAC involvement (IAC group and non-IAC group, respectively)., Results: A total of 14 of 23 ears showed involvement of the IAC. There were no significant differences in age, side of otosclerosis, or preoperative hearing threshold between the two groups. The mean postoperative AC and BC thresholds and ABG of the IAC group were significantly poorer (45.7 dB, 33.8 dB, and 11.8 dB, respectively) than those of the nonIAC group (24.1 dB, 20.0 dB, and 4.1 dB, respectively)., Conclusions: Cochlear otosclerosis with cavitating lesions involving the IAC showed significantly poorer postoperative audiological outcomes than those without any cavitating lesion. Cavitation extending to the IAC may act as a third window providing a route for sound energy shunting, and thus precluding successful hearing outcome in some subjects with cavitating otosclerosis after stapedotomy.

Objectives: The aim of this study was to compare the diagnostic performance of a deep learning algorithm with that of radiologists in diagnosing maxillary sinusitis on Waters' view radiographs., Materials and Methods: Among 80,475 Waters' view radiographs, examined between May 2003 and February 2017, 9000 randomly selected cases were classified as normal or maxillary sinusitis based on radiographic findings and divided into training (n = 8000) and validation (n = 1000) sets to develop a deep learning algorithm. Two test sets composed of Waters' view radiographs with concurrent paranasal sinus computed tomography were labeled based on computed tomography findings: one with temporal separation (n = 140) and the other with geographic separation (n = 200) from the training set. Area under the receiver operating characteristics curve (AUC), sensitivity, and specificity of the algorithm and 5 radiologists were assessed. Interobserver agreement between the algorithm and majority decision of the radiologists was measured. The correlation coefficient between the predicted probability of the algorithm and average confidence level of the radiologists was determined., Results: The AUCs of the deep learning algorithm were 0.93 and 0.88 for the temporal and geographic external test sets, respectively. The AUCs of the radiologists were 0.83 to 0.89 for the temporal and 0.75 to 0.84 for the geographic external test sets. The deep learning algorithm showed statistically significantly higher AUC than radiologist in both test sets. In terms of sensitivity and specificity, the deep learning algorithm was comparable to the radiologists. A strong interobserver agreement was noted between the algorithm and radiologists (Cohen κ coefficient, 0.82). The correlation coefficient between the predicted probability of the algorithm and confidence level of radiologists was 0.89 and 0.84 for the 2 test sets, respectively., Conclusions: The deep learning algorithm could diagnose maxillary sinusitis on Waters' view radiograph with superior AUC and comparable sensitivity and specificity to those of radiologists.

Objective: Distinguishing intralabyrinthine schwannoma (ILS) from labyrinthitis is crucial in deciding patient management between surgery and medication; however, the clinical and radiological differentiation between ILS and labyrinthitis is difficult, especially when labyrinthitis shows contrast-enhancement mimicking ILS on magnetic resonance imaging (MRI). This study aimed to evaluate the quantitative characteristics of signal intensity on 3T MRI for differentiating ILS from contrast-enhancing labyrinthitis (CEL)., Study Design: Retrospective study., Setting: Tertiary referral center., Patients: Between July 2003 and June 2017, 9 subjects diagnosed with ILS (16 MRI cases) and 9 subjects diagnosed with CEL (9 MRI cases) were enrolled in the study., Main Outcome Measures: Normalized signal intensity on contrast-enhanced T1-weighted image (nCE-T1), normalized signal intensity on T2-weighted image (nT2), and normalized signal intensity on contrast-enhanced fluid-attenuated inversion recovery image (nFLAIR) were measured and compared between ILS and CEL. The diagnostic performance of these values was assessed using receiver operating characteristic (ROC) analysis., Results: In ILS, the nCE-T1 and the nT2 were significantly higher and lower, respectively, than in CEL (all, p < 0.05); and the nFLAIR did not significantly differ (p > 0.05). The maximal nCE-T1 achieved the highest area under the curve (AUC) in differentiating ILS and CEL, followed by the mean nCE-T1, the mean nT2, and the maximal nT2. Combination of the nCE-T1 and the nT2 showed higher AUC than the nCE-T1 alone, but without statistical significance (p = 0.340)., Conclusions: Quantitative measurement of the signal intensity on MRI can be a viable imaging tool for differentiating ILS from CEL.

Objective: Grade II diffuse gliomas (DGs) with isocitrate dehydrogenase (IDH) mutations are associated with better prognosis than their IDH wild-type counterparts. We sought to determine the MRI characteristics associated with IDH mutational status and ascertain whether MRI considered in combination with IDH mutational status can better predict the clinical outcomes of grade II DGs., Materials and Methods: Preoperative MRI examinations were retrospectively studied for qualitative tumor characteristics, including location, extent, cortical involvement, margin sharpness, cystic component, mineralization or hemorrhage, and contrast enhancement. Quantitative diffusion and perfusion metrics were also assessed. Logistic regression and ROC analyses were used to evaluate the relationship between MRI features and IDH mutational status. The association between IDH mutational status, 1p19q codeletion, MRI features, extent of resection, and clinical outcomes was assessed by Kaplan-Meier and Cox proportional hazards models., Results: Of 100 grade II DGs, 78 were IDH mutant and 22 were IDH wild type. IDH wild-type tumors were associated with older age, multifocality, brainstem involvement, lack of cystic change, and a lower apparent diffusion coefficient (ADC). Multivariable regression showed that age older than 45 years as well as low minimum ADC (ADC min ), mean ADC, and maximum ADC values were independently associated with IDH mutational status. Of these, an ADC min threshold of 0.9 × 10 -3 mm 2 /s or less provided the greatest sensitivity and specificity (91% and 76%, respectively) in defining IDH wild-type grade II DGs. Combining low ADC min with IDH wild-type status conferred worse outcomes than did IDH wild-type status alone., Conclusion: IDH wild-type grade II DGs are associated with a lower ADC and poor clinical outcomes. Combining IDH mutational status and ADC may allow more accurate prediction of clinical outcomes for patients with grade II DGs.

Objective: To simulate the B 1 -inhomogeneity-induced variation of pharmacokinetic parameters on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)., Materials and Methods: B 1 -inhomogeneity-induced flip angle (FA) variation was estimated in a phantom study. Monte Carlo simulation was performed to assess the FA-deviation-induced measurement error of the pre-contrast R 1 , contrast-enhancement ratio, Gd-concentration, and two-compartment pharmacokinetic parameters (K trans , v e , and v p )., Results: B 1 -inhomogeneity resulted in -23-5% fluctuations (95% confidence interval [CI] of % error) of FA. The 95% CIs of FA-dependent % errors in the gray matter and blood were as follows: -16.7-61.8% and -16.7-61.8% for the pre-contrast R 1 , -1.0-0.3% and -5.2-1.3% for the contrast-enhancement ratio, and -14.2-58.1% and -14.1-57.8% for the Gd-concentration, respectively. These resulted in -43.1-48.4% error for K trans , -32.3-48.6% error for the v e , and -43.2-48.6% error for v p . The pre-contrast R 1 was more vulnerable to FA error than the contrast-enhancement ratio, and was therefore a significant cause of the Gd-concentration error. For example, a -10% FA error led to a 23.6% deviation in the pre-contrast R 1 , -0.4% in the contrast-enhancement ratio, and 23.6% in the Gd-concentration. In a simulated condition with a 3% FA error in a target lesion and a -10% FA error in a feeding vessel, the % errors of the pharmacokinetic parameters were -23.7% for K trans , -23.7% for v e , and -23.7% for v p ., Conclusion: Even a small degree of B 1 -inhomogeneity can cause a significant error in the measurement of pharmacokinetic parameters on DCE-MRI, while the vulnerability of the pre-contrast R 1 calculations to FA deviations is a significant cause of the miscalculation.

Objective: Hyperintense acute reperfusion marker (HARM) is defined as delayed CSF enhancement on FLAIR images in patients with acute stroke and was observed in follow-up FLAIR images after initial MRI with contrast material administration. We hypothesized that different imaging findings of HARM could be present depending on the timing of FLAIR imaging after contrast material administration., Subjects and Methods: Of 218 consecutive patients with acute stroke or transient ischemic attack over 3 months, 12 with linear contrast enhancement on the cortical surface in initial FLAIR images underwent serial FLAIR imaging. Initial FLAIR images were obtained 5 minutes after contrast material administration, and follow-up unenhanced FLAIR images were obtained 2.5-29 hours (mean, 13.2 hours) after initial FLAIR imaging. The enhancement patterns between initial and follow-up FLAIR images were compared., Results: In all 12 patients, initial contrast-enhanced FLAIR images showed focal or multifocal linear contrast enhancement along the cortical surface near acute infarctions. On follow-up unenhanced FLAIR images, initial cortical enhancement spread diffusely and filled the subarachnoid space., Conclusion: HARM in acute stroke can be detected earlier than previously reported on initial contrast-enhanced FLAIR images. Different imaging findings of HARM depend on the timing of FLAIR imaging after contrast material administration.

Introduction: We developed a new neuroprognostication method for cardiac arrest (CA) using the relative volume of the most dominant cluster of low apparent diffusion coefficient (ADC) voxels and tested its performance in a multicenter setting., Methods: Adult (>15 years) out-of-hospital CA patients from three different facilities who underwent an MRI 12h after resuscitation were retrospectively analyzed. Patients with unknown long-term prognosis or poor baseline neurologic function were excluded. Average ADCs (mean and median), LADCV (relative volume of low-ADC voxels) and DC-LADCV (relative volume of most dominant cluster of low-ADC voxels) were extracted using different thresholds between 400 and 800 × 10(-6) mm(2) s(-1) at 10 × 10(-6) mm(2) s(-1) intervals. Area under the receiver operating characteristic curve (AUROC) and sensitivity for poor outcome (6-month cerebral performance category score >2) while maintaining 100% specificity were measured., Results: 110 patients were analyzed. Average ADCs showed fair performance with an AUROC of 0.822 (95% confidence interval [CI], 0.744-0.900) for the mean and 0.799 (95% CI, 0.716-0.882) for the median. LADCV showed better performance with a higher AUROC (maximum, 0.925) in an ADC threshold range of 400 to 690 × 10(-6) mm(2) s(-1). DC-LADCV showed the best performance with a higher AUROC (maximum, 0.955) compared with LADCV in an ADC threshold range of 600 to 680 × 10(-6) mm(2) s(-1). DC-LADCV had a high sensitivity for poor outcomes (>80%) in a wide threshold range from 400 to 580 × 10(-6) mm(2) s(-1) with a maximum of 89.2%., Conclusions: Quantitative analysis using DC-LADCV showed impressive performance in determining the prognosis of out-of-hospital CA patients in a multicenter setting., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Objective: Both jugular venous reflux (JVR) and cavernous dural arteriovenous fistula (DAVF) manifest as abnormal venous signal intensities on time-of-flight (TOF) MR angiography (MRA). We investigated brain MRI and MRA findings that might differentiate JVR from cavernous DAVF., Materials and Methods: Forty-one patients with abnormal venous signal intensities on TOF MRA in the cavernous sinus and its vicinity were selected from 1508 patients who had undergone TOF MRA over the previous 6 months. For comparison, the examinations of 26 patients with cavernous DAVF who had undergone imaging over the previous 8 years were collected. The following findings were assessed: the side and location of abnormal venous signal intensities on intracranial TOF MRA; the signal intensity of the proximal jugular vein on T2-weighted imaging; whether there was early opacification of the cavernous sinus in the arterial phase of contrast-enhanced MRA (CE-MRA); the side of jugular venous drainage in the arteriovenous phase of CE-MRA; and whether retrograde jugular venous flow was seen on neck TOF MRA., Results: Abnormal venous signal intensities were seen on the left side in 73% of patients with JVR and 58% of patients with cavernous DAVF; involvement of the cavernous sinus was found in 12% of patients with JVR and 100% of patients with cavernous DAVF. Increased signal intensity in the ipsilateral jugular vein on T2-weighted imaging was found in 73% of JVR patients and 4% of cavernous DAVF patients. Early opacification of the cavernous sinus in the arterial phase of CE-MRA, ipsilateral jugular venous drainage in the arteriovenous phase of CE-MRA, and ipsilateral retrograde jugular venous flow on neck TOF MRA were found in 0%, 0%, and 63%, respectively, of JVR patients and in 100%, 100%, and 0%, respectively, of cavernous DAVF patients., Conclusion: JVR and cavernous DAVF can be differentiated from one another using MRI and MRA.