Reducing false positives in deep learning-based brain metastasis detection by using both gradient-echo and spin-echo contrast-enhanced MRI: validation in a multi-center diagnostic cohort.

OBJECTIVES: To develop a deep learning (DL) for detection of brain metastasis (BM) that incorporates both gradient- and turbo spin-echo contrast-enhanced MRI (dual-enhanced DL) and evaluate it in a clinical cohort in comparison with human readers and DL using gradient-echo-based imaging only (GRE DL). MATERIALS AND METHODS: DL detection was developed using data from 200 patients with BM (training set) and tested in 62 (internal) and 48 (external) consecutive patients who underwent stereotactic radiosurgery and diagnostic dual-enhanced imaging (dual-enhanced DL) and later guide GRE imaging (GRE DL). The detection sensitivity and positive predictive value (PPV) were compared between two DLs. Two neuroradiologists independently analyzed BM and reference standards for BM were separately drawn by another neuroradiologist. The relative differences (RDs) from the reference standard BM numbers were compared between the DLs and neuroradiologists. RESULTS: Sensitivity was similar between GRE DL (93%, 95% confidence interval [CI]: 90-96%) and dual-enhanced DL (92% [89-94%]). The PPV of the dual-enhanced DL was higher (89% [86-92%], p < .001) than that of GRE DL (76%, [72-80%]). GRE DL significantly overestimated the number of metastases (false positives; RD: 0.05, 95% CI: 0.00-0.58) compared with neuroradiologists (RD: 0.00, 95% CI: - 0.28, 0.15, p < .001), whereas dual-enhanced DL (RD: 0.00, 95% CI: 0.00-0.15) did not show a statistically significant difference from neuroradiologists (RD: 0.00, 95% CI: - 0.20-0.10, p = .913). CONCLUSION: The dual-enhanced DL showed improved detection of BM and reduced overestimation compared with GRE DL, achieving similar performance to neuroradiologists. CLINICAL RELEVANCE STATEMENT: The use of deep learning-based brain metastasis detection with turbo spin-echo imaging reduces false positive detections, aiding in the guidance of stereotactic radiosurgery when gradient-echo imaging alone is employed. KEY POINTS: •Deep learning for brain metastasis detection improved by using both gradient- and turbo spin-echo contrast-enhanced MRI (dual-enhanced deep learning). •Dual-enhanced deep learning increased true positive detections and reduced overestimation. •Dual-enhanced deep learning achieved similar performance to neuroradiologists for brain metastasis counts.

Automated Idiopathic Normal-Pressure Hydrocephalus Diagnosis via Artificial Intelligence-Based 3D T1 MRI Volumetric Analysis.

BACKGROUND AND PURPOSE: Idiopathic normal pressure hydrocephalus (iNPH) is reversible dementia, that is underdiagnosed. The purpose of this study was to develop an automated diagnostic method for iNPH using artificial intelligence techniques with a T1-weighted MRI scan. MATERIALS AND METHODS: We quantified iNPH, Parkinson's disease, Alzheimer's disease, and healthy control patients on T1-weighted 3D brain MRI scans using 452 scans for training and 110 scans for testing. Automatic component measurement algorithms were developed for Evans' index, Sylvian fissure enlargement, high-convexity tightness, callosal angle, and normalized lateral ventricle volume. XGBoost models were trained for both automated measurements and manual labels for iNPH prediction. RESULTS: A total of 452 patients (200 men; mean age ± standard deviation, 73.2 ± 6.5 years) were included in the training set. Of the 452 patients, 111 (24.6%) had iNPH. We obtained AUC values of 0.956 for automatically measured high-convexity tightness and 0.830 for Sylvian fissure enlargement. Intra-class correlation values of 0.824 for the callosal angle and 0.924 for Evans' index were measured. Using the decision tree of the XGBoost model, the model trained on manual labels obtained an average cross-validation AUC of 0.988 on the training set and 0.938 on the unseen test set, while the fully automated model obtained a cross-validation AUC of 0.983 and an unseen test AUC of 0.936. CONCLUSION: We demonstrated a machine-learning algorithm capable of diagnosing iNPH from a 3D T1-weighted MRI scan that is robust to the failure. We propose a method to scan large numbers of 3D T1-weighted MRI scans with minimal human intervention, making possible large-scale iNPH screening. ABBREVIATIONS: iNPH = idiopathic normal-pressure hydrocephalus; PD = Parkinson's disease; AD = Alzheimer's disease; HC = healthy control; CSF = cerebrospinal fluid; DESH = disproportionately enlarged subarachnoid space hydrocephalus; 3D = three-dimensional.

Gerstmann-Sträussler-Scheinker Disease: A Case Report.

Gerstmann-Sträussler-Scheinker (GSS) disease is a rare hereditary prion disease which is clinically characterized by a progressive cerebellar ataxia followed by cognitive impairment. We report a rare case of GSS disease in a 39-year-old male patient who complained of a progressive gait disturbance followed by dysarthria with cognitive impairment, after five months from the onset of initial symptom. His brain MRI scan revealed multifocal symmetric diffusion restricted lesions with T2/FLAIR hyperintensities in bilateral cerebral cortices, basal ganglia, and thalami. His family members also manifested similar symptoms in their 40-50s, suggesting the possibility of a genetic disease. Finally, he was genetically diagnosed with GSS disease by real-time quaking-induced conversion and prion protein (PRNP) gene sequencing test.

Persistent Primitive Olfactory Artery Type 4 with Fusiform Aneurysm: A Case Report.

The persistent primitive olfactory artery (PPOA) is a rare variant of the anterior cerebral artery, first reported in 1979. It reportedly has a high correlation with the development of aneurysms, owing to the hemodynamic stress induced by the structural characteristics of the hairpin turn. Herein, we present a rare case of PPOA type 4 with a fusiform aneurysm at the hairpin turn segment in a 46-year-old female with occasional headaches. Time-of-flight MR angiography and transfemoral cerebral angiography revealed an unusual branch arising from the left A1 segment, running anteromedially along the ipsilateral olfactory tract, and turning the hairpin posterior to the olfactory bulb. This branch continued into the left accessory middle cerebral artery, and a fusiform aneurysm was observed at the hairpin segment. No further treatment was performed, and follow-up imaging was recommended. Nevertheless, it is essential to recognize and diagnose these rare variations.

Prolapsed Uterine Smooth Muscle Tumor of Uncertain Malignant Potential: A Case Report and Review of Radiologic Findings.

INTRODUCTION: Uterine smooth muscle tumor of uncertain malignant potential (STUMP) is a rare tumor that arises in the myometrium of the uterus. It is regarded as an intermediate malignant tumor according to the recent World Health Organization classification. Few studies have reported the radiologic findings of STUMP, and the differentiation of STUMP from leiomyoma remains controversial. CASE DESCRIPTION: A 42-year-old nulliparous female presented at our institution with massive vaginal bleeding. Radiological studies, including ultrasonography, computed tomography (CT), and magnetic resonance imaging, revealed an oval-shaped mass with well-defined margins in the uterus protruding into the vagina. The patient underwent a total abdominal hysterectomy, and the final pathology was confirmed as STUMP. CONCLUSION: Distinguishing STUMP from leiomyomas based solely on radiological findings can be challenging. However, if the uterine mass appears as a single mass lacking acoustic shadowing on ultrasound and demonstrates diffusion restriction with high T2 signal intensity on magnetic resonance imaging, consideration of STUMP may be necessary for proper patient management, given the poor prognosis associated with this tumor.

Addendum: Outpatient Day-Care Management of Unruptured Intracranial Aneurysm: A Retrospective Cohort Study.

This corrects the article on p. 828 in vol. 23, PMID: 35762182.

Huge Primary Clear Cell Hepatocellular Carcinoma: a Case Report and Review of Radiologic Findings.

INTRODUCTION: Clear cell hepatocellular carcinoma (HCC) is a rare subtype of HCC. Histologically, clear cell HCC is characterized by the cytoplasmic accumulation of glycogen with a clear cell appearance, constituting > 80% of tumor cells. Radiologically, clear cell HCC demonstrates early enhancement and washout similar to conventional HCC. Occasionally, enhancing capsule and intratumoral fat are accompanied by clear cell HCC. CASE DESCRIPTION: A 57-year-old male presented to our hospital with right upper quadrant abdominal pain. Ultrasonography, computed tomography, and magnetic resonance imaging revealed a large mass with a well-defined margin in the right hemiliver. The patient underwent a right hemihepatectomy, and the final histopathology revealed clear cell-type HCC. CONCLUSION: Distinguishing clear cell types from other types of HCC solely based on radiological findings is challenging. If hepatic tumors exhibit encapsulated margins, enhancing rims, intratumoral fat, and arterial phase hyperenhancement/washout pattern despite their large size, consideration of clear cell subtypes in the differential diagnosis list will aid patient management, implying better prognosis than not-otherwise-specified HCC.

Comparison of Safety and Diagnostic Efficacy of Iohexol 240 mgI/mL, Iopamidol 250 mgI/mL, and Iodixanol 270 mgI/mL in Cerebral Angiography: A Prospective, Multicenter Study.

PURPOSE: This multicenter prospective study aimed to evaluate the quality and diagnostic effectiveness of cerebral angiography images obtained using low-concentration iodinated contrast agents (iohexol 240 mgI/mL, iopamidol 250 mgI/mL, and iodixanol 270 mgI/mL) and to assess the safety thereof. The study addresses the need for safer contrast agent alternatives without compromising the diagnostic quality of identifying cerebrovascular disease. MATERIALS AND METHODS: Conducted in 5 medical centers in South Korea, we enrolled patients aged 19 years or older who were referred for diagnostic cerebral angiography under non-emergency conditions, excluding those with specific health conditions and sensitivities. The study design included a prospective, observational approach with a 1-way analysis of variance (ANOVA) for sample size calculation, aiming for a total sample of 231 participants for adequate power. Image quality was evaluated using a 4-level scale by 2 independent, blinded radiologists, and adverse reactions were monitored both immediately and up to 7 days post-procedure. Statistical analysis involved 1-way ANOVA and Kruskal-Wallis tests to assess the image quality and safety profiles of the contrast agents. RESULTS: Among 266 patients screened, 243 were included in the final analysis. The evaluation revealed no statistically significant differences in image quality among the 3 types of low-concentration contrast agents. Adverse events were observed in 28.8% of patients, with 27.2% experiencing acute reactions, primarily mild reactions, and 3.3% experiencing delayed reactions. The overall safety profile showed no significant changes in vital signs or electrocardiogram readings before and after contrast agent injection. CONCLUSION: Using low-concentration iodinated contrast agents for cerebral angiography provides image quality comparable to that of conventional high-concentration agents, with no significant increase in adverse events, suggesting a safer alternative for patients.

Outpatient Day-Care Management of Unruptured Intracranial Aneurysm: A Retrospective Cohort Study.

OBJECTIVE: This study aimed to assess the outcomes of outpatient day-care management of unruptured intracranial aneurysm (UIA), and to present the risks associated with different management strategies by comparing the outcomes and adverse events between outpatient day-care management and management with longer admission periods. MATERIALS AND METHODS: This retrospective cohort study used prospectively registered data and was approved by a local institutional review board. We enrolled 956 UIAs from 811 consecutive patients (mean age ± standard deviation, 57 ± 10.7 years; male:female = 247:564) from 2017 to 2020. We compared the outcomes after embolization among the different admission-length groups (1, 2, and ≥ 3 days). The outcomes included pre- and post-modified Rankin Scale (mRS) scores and rates of adverse events, cure, recurrence, and reprocedure. Events were defined as any cerebrovascular problems, including minor and major stroke, death, or hemorrhage. RESULTS: The mean admission period was 2 days, and 175 patients (191 aneurysms), 551 patients (664 aneurysms), and 85 patients (101 aneurysms) were discharged on the day of the procedure, day 2, and day 3 or later, respectively. During the mean 17-month follow-up period (range 6-53 months; 2757 patient years), no change in post-mRS was observed compared to pre-mRS in 99.6% of patients. Cure was achieved in 95.6% patients; minimal recurrence that did not require re-procedure occurred in 3.5% patients, and re-procedure was required in 2.3% (22 of 956) patients due to progressive enlargement of the recurrent sac during follow up (mean 17 months, range, 6-53 months). There were eight adverse events (0.8%), including five cerebrovascular (two major stroke, two minor strokes and one transient ischemic stroke), and three non-cerebrovascular events. Statistical comparison between groups with different admission lengths (1, 2, and ≥ 3 days) revealed no difference in the outcomes. CONCLUSION: This study revealed no difference in outcomes and adverse events according to the admission period, and suggested that UIA could be managed by outpatient day-care embolization.

Synergistic immunosuppressive effects of rosmarinic acid and rapamycin in vitro and in vivo.

BACKGROUND: We previously demonstrated that rosmarinic acid (RosA) inhibits T-cell antigen receptor-induced T-cell activation and proliferation. In this study, we evaluated the ability of RosA alone and in conjunction with currently used immunosuppressive drugs to inhibit in vitro splenic T-cell proliferation and prolong skin graft survival in vivo. METHODS: Mouse splenic T-cell proliferation assays were performed in the presence of RosA alone or in combination with cyclosporine, rapamycin (Rapa), or prednisone (Pred). The in vivo synergistic efficacy of RosA and Rapa was evaluated in the mouse skin allograft model. RESULTS: RosA combined with Rapa or prednisone synergistically inhibited splenic T-cell proliferation, whereas the combination of RosA and cyclosporine additively inhibited T-cell proliferation. The combination of RosA and Rapa synergistically prolonged allograft survival. CONCLUSIONS: We conclude that the combination of RosA and Rapa promotes immunosuppressive effects.

Rosmarinic acid inhibits Ca2+-dependent pathways of T-cell antigen receptor-mediated signaling by inhibiting the PLC-gamma 1 and Itk activity.

Rosmarinic acid (RosA) is a hydroxylated compound frequently found in herbal plants and is mostly responsible for anti-inflammatory and antioxidative activity. Previously, we observed that RosA inhibited T-cell antigen receptor (TCR)- induced interleukin 2 (IL-2) expression and subsequent T-cell proliferation in vitro. In this study, we investigated in detail inhibitory mechanism of RosA on TCR signaling, which ultimately activates IL-2 promoter by activating transcription factors, such as nuclear factor of activated T cells (NF-AT) and activating protein-1 (AP-1). Interestingly, RosA inhibited NF-AT activation but not AP-1, suggesting that RosA inhibits Ca(2+)-dependent signaling pathways only. Signaling events upstream of NF-AT activation, such as the generation of inositol 1,4,5-triphosphate and Ca(2+) mobilization, and tyrosine phosphorylation of phospholipase C-gamma 1 (PLC-gamma 1) were strongly inhibited by RosA. Tyrosine phosphorylation of PLC-gamma 1 is largely dependent on 3 kinds of protein tyrosine kinases (PTKs), ie, Lck, ZAP-70, and Itk. We found that RosA efficiently inhibited TCR-induced tyrosine phosphorylation and subsequent activation of Itk but did not inhibit Lck or ZAP-70. ZAP-70-dependent signaling pathways such as the tyrosine phosphorylation of LAT and SLP-76 and serine/threonine phosphorylation of mitogen-activated protein kinases (MAPKs) were intact in the presence of RosA, confirming that RosA suppresses TCR signaling in a ZAP-70-independent manner. Therefore, we conclude that RosA inhibits TCR signaling leading to Ca(2+) mobilization and NF-AT activation by blocking membrane-proximal events, specifically, the tyrosine phosphorylation of inducible T cells kinase (Itk) and PLC-gamma 1.