Elevated plasma levels of factor VIII enhance arterial thrombus formation on erosive smooth muscle cell-rich neointima but not normal intima in rabbits.

BACKGROUND: Plaque erosion, a type of coronary atherothrombosis, involves superficial injury to smooth muscle cell (SMC)-rich plaques. Elevated levels of coagulation factor VIII (FVIII) correlate with an increased ischemic heart disease risk. FVIII may contribute to thrombus formation on eroded plaques. AIMS: We aimed to elucidate the role of elevated FVIII in arterial thrombus formation within SMC-rich neointima in rabbits. METHODS AND RESULTS: We assessed the effect of recombinant human FVIII (rFVIII) on blood coagulation in vitro and platelet aggregation ex vivo. An SMC-rich neointima was induced through balloon injury to the unilateral femoral artery. Three weeks after the first balloon injury, superficial erosive injury and thrombus formation were initiated with a second balloon injury of the bilateral femoral arteries 45 min after the administration of rFVIII (100 IU/kg) or saline. The thrombus area and contents were histologically measured 15 min after the second balloon injury. rFVIII administration reduced the activated partial thromboplastin time and augmented botrocetin-induced, but not collagen- or adenosine 5'-diphosphate-induced, platelet aggregation. While rFVIII did not influence platelet-thrombus formation in normal intima, it increased thrombus formation on SMC-rich neointima post-superficial erosive injury. Enhanced immunopositivity for glycoprotein IIb/IIIa and fibrin was observed in rFVIII-administered SMC-rich neointima. Neutrophil count in the arterial thrombus on the SMC-rich neointima correlated positively with thrombus size in the control group, unlike the rFVIII group. CONCLUSIONS: Increased FVIII contributes to thrombus propagation within erosive SMC-rich neointima, highlighting FVIII's potential role in plaque erosion-related atherothrombosis.

A case of multifocal sclerosis angiomatoid nodular transformations of the spleen occurring after partial splenic infarction with transcatheter arterial embolization for splenic artery aneurysm.

A 48-year-old woman underwent transcatheter arterial embolization (TAE) for a splenic artery aneurysm, which resulted in a partial splenic infarction in the middle lobe. Five years after TAE, a 20-mm diameter mass in the noninfarcted area of the spleen was detected on imaging, which grew to 25 mm in diameter after 6 months. MRI after gadolinium administration showed a 35 × 34 mm mass within the superior pole and 15 × 12 mm mass within the inferior pole. The patient underwent laparoscopic splenectomy and had an uneventful postoperative recovery. No evidence of recurrence was observed during the 2-year follow-up period after surgery. The mass was pathologically confirmed to be sclerosing angiomatoid nodular transformation (SANT) of the spleen. While some studies hypothesize that SANT is a response to vascular injury or trauma, to the best of our knowledge, there have been no previous reports of SANT occurring after procedures directly affecting splenic blood flow. Additionally, multifocal SANTs are reported to be very rare, accounting for only 4.7% of all reported SANTs of the spleen. We highlight a rare course of SANT of the spleen and discuss the possible relationship between blood flow abnormalities and the appearance of SANT.

[Usefulness of Voxel-Based Quantification (VBQ) Smoothing in Relaxation Time Mapping].

PURPOSE: Voxel-based quantification (VBQ) smoothing is a technique used to smooth quantitative parametric maps in the Montreal Neurological Institute standard space. Although VBQ smoothing could suppress changes in quantitative values at tissue boundaries, its effectiveness on relaxation time (T1 and T2 values and proton density PD) maps has not been investigated. The purpose of this study was to clarify the usefulness of VBQ smoothing in relaxation time mapping. METHOD: T1 and T2 values and PD maps of the brains of 20 healthy participants were obtained using a two-dimensional multi-dynamic multi-echo sequence. VBQ and Gaussian smoothing were applied to the relaxation time maps by varying the kernel size by 1 mm from 1 to 6 mm. Changes in relaxation time before and after VBQ and Gaussian smoothing for the putamen, caudate nucleus, substantia nigra, and corpus callosum on the relaxation time maps were evaluated. RESULT: The changes in relaxation time after VBQ smoothing application were smaller than those in that after Gaussian smoothing application. Although the differences in the relaxation time for all tissues before and after VBQ and Gaussian smoothing applications increased with increasing kernel size for all relaxation times for both methods, the changes in the relaxation time for VBQ smoothing were smaller than those in that for Gaussian smoothing. CONCLUSION: VBQ smoothing can suppress the change in the relaxation time on the boundary of the tissue and is thus a useful smoothing technique in relaxation time mapping.

Lymphomas of Central Nervous System.

Central nervous system (CNS) lymphoma consists of primary central nervous system lymphoma (PCNSL) and secondary CNS involvement by systemic lymphoma. This chapter focuses on the former. PCNSL is a relative rare disease, accounting for approximately 2.4-4.9% of all primary CNS tumors. It is an extra-nodal variant of non-Hodgkin's lymphoma (NHL), confined to the brain, leptomeninges, spinal cord, and eyes, with no systemic involvement. Recently, elderly patients (≥ 60 years) are increasing. Histologically, B cell blasts, which originate from late germinal center exit B cell, are growing and homing in CNS. Immunohistochemically, these cells are positive for PAX5, CD19, CD20, CD22, and CD79a. PCNSL shows relatively characteristic appearances on CT, MR imaging, and PET. Treatment first line of PCNSL is HD-MTX-based chemotherapy with or without rituximab and irradiation. Severe side-effect of this treatment is delayed onset neurotoxicity, which cause of cognitive impairment. Therefore, combined chemotherapy alone or chemotherapy with reduced-dose irradiation is more recommended for elderly patients. There is no established standard care for relapse of the PCNSLs. Temsirolimus, lenalidomide, temozolomide, and Bruton's tyrosine kinase (BTK) inhibitor ibrutinib are candidates for refractory patients. The prognosis of PCNSL has significantly improved over the last decades (median OS: 26 months, 5-year survival: 31%). Younger than 60 age and WHO performance status less than < or = 1 are associated with a significantly better overall survival.

Novel Strategy Involving High-Dose Chemotherapy with Stem Cell Rescue Followed by Intrathecal Topotecan Maintenance Therapy without Whole-Brain Irradiation for Atypical Teratoid/Rhabdoid Tumors.

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare aggressive central nervous system tumor that typically affects children under three years old and has poor survival with a high risk for neurologic deficits. The primary purpose of this study was to successfully treat the disease and delay or avoid whole-brain radiotherapy for children with AT/RT. A retrospective analysis was performed for six children diagnosed with AT/RT and treated with multimodal treatment at a single institute between 2014 and 2020. Furthermore, germline SMARCB1 aberrations and MGMT methylation status of the tumors were analyzed. One patient who did not receive a modified IRS-III regimen replaced with ifosphamide, carboplatin, and etoposide (ICE) in induction chemotherapy was excluded from this analysis. Five patients who received ICE therapy were under three years old. After a surgical approach, they received intensive chemotherapy and high-dose chemotherapy with autologous peripheral blood stem cell transplantation (HDCT/autoPBSCT) followed by intrathecal topotecan maintenance therapy. Three patients underwent single HDCT/autoPBSCT, and the other two received sequential treatment. Two patients with germline SMARCB1 aberrations and metastases died of progressive AT/RT or therapy-related malignancy, while 3 with localized tumors without germline SMARCB1 aberrations remained alive. One survivor received local radiotherapy only, while the other two did not undergo radiotherapy. All three surviving patients were able to avoid whole-brain radiotherapy. Our results suggest that AT/RT patients with localized tumors without germline SMARCB1 aberrations can be rescued with multimodal therapy, including induction therapy containing ICE followed by HDCT/autoPBSCT and intrathecal topotecan maintenance therapy without radiotherapy. Further large-scale studies are necessary to confirm this hypothesis.

[Evaluation of the Accuracy of Relaxation Time Measurements Using 3D-QALAS at 3.0 T MRI and Comparison with 2D-MDME].

PURPOSE: Three-dimensional (3D) quantification using an interleaved Look-Locker acquisition sequence with a T2 preparation pulse (QALAS) is a quantitative sequence used to measure relaxation times. The accuracy of the relaxation time measurement of 3D-QALAS at 3.0 T and the bias of 3D-QALAS have not yet been assessed. The purpose of this study was to clarify the accuracy of the relaxation time measurements using 3D-QALAS at 3.0 T MRI. METHODS: The accuracy of the T1 and T2 values for 3D-QALAS was evaluated using a phantom. Subsequently, the T1 and T2 values and proton density of the brain parenchyma in healthy subjects were measured using 3D-QALAS and compared with those of 2D multi-dynamic multi-echo (MDME). RESULTS: In the phantom study, the average T1 value of 3D-QALAS was 8.3% prolonged than that for conventional inversion recovery spin-echo; the average T2 value for 3D-QALAS was 18.4% shorter than that for multi-echo spin-echo. The in vivo assessment showed that the mean T1 and T2 values and PD for 3D-QALAS were prolonged by 5.3%, shortened by 9.6%, and increased by 7.0%, respectively, compared with those for 2D-MDME. CONCLUSION: Although 3D-QALAS at 3.0 T has high accuracy T1 value, which is less than 1000 ms, the T1 value could be overestimated for tissues with it longer than that T1 value. The T2 value for 3D-QALAS could be underestimated for tissues with T2 values, and this tendency increases with longer T2 values.

A clear presentation of intracranial hypostasis on PMCT.

Intracranial hypostasis is a common postmortem change evident on postmortem CT (PMCT), but can be readily misinterpreted as subdural hematoma by inexperienced physicians. Although PMCT is necessarily lacking contrast enhancement, we reconstructed hypostatic sinuses into three-dimensional images resembling the results of in vivo venography. This simple methodology facilitates easy recognition of intracranial hypostasis.

Importance of Age and Noncontrast-Enhancing Tumor as Biomarkers for Isocitrate Dehydrogenase-Mutant Glioblastoma: A Multicenter Study.

PURPOSE: This study aimed to investigate the most useful clinical and magnetic resonance imaging (MRI) parameters for differentiating isocitrate dehydrogenase (IDH)-mutant and -wildtype glioblastomas in the 2016 World Health Organization Classification of Tumors of the Central Nervous System. METHODS: This multicenter study included 327 patients with IDH-mutant or IDH-wildtype glioblastoma in the 2016 World Health Organization classification who preoperatively underwent MRI. Isocitrate dehydrogenase mutation status was determined by immunohistochemistry, high-resolution melting analysis, and/or IDH1/2 sequencing. Three radiologists independently reviewed the tumor location, tumor contrast enhancement, noncontrast-enhancing tumor (nCET), and peritumoral edema. Two radiologists independently measured the maximum tumor size and mean and minimum apparent diffusion coefficients of the tumor. Univariate and multivariate logistic regression analyses with an odds ratio (OR) were performed. RESULTS: The tumors were IDH-wildtype glioblastoma in 306 cases and IDH-mutant glioblastoma in 21. Interobserver agreement for both qualitative and quantitative evaluations was moderate to excellent. The univariate analyses revealed a significant difference in age, seizure, tumor contrast enhancement, and nCET ( P < 0.05). The multivariate analysis revealed significant difference in age for all 3 readers (reader 1, odds ratio [OR] = 0.960, P = 0.012; reader 2, OR = 0.966, P = 0.048; reader 3, OR = 0.964, P = 0.026) and nCET for 2 readers (reader 1, OR = 3.082, P = 0.080; reader 2, OR = 4.500, P = 0.003; reader 3, OR = 3.078, P = 0.022). CONCLUSIONS: Age and nCET are the most useful parameters among the clinical and MRI parameters for differentiating IDH-mutant and IDH-wildtype glioblastomas.

Brain structural changes in patients with chronic methylmercury poisoning in Minamata.

Exploratory whole-brain studies in patients suffering from methylmercury (MeHg) poisoning have not been conducted. We aimed to evaluate the neuroanatomical differences between patients with chronic MeHg poisoning and healthy volunteers via magnetic resonance (MR) imaging. Patients included in this case-control study were divided into three categories based on whether MeHg exposure occurred in utero, under 15 years of age, or over 15 years of age, as fetal-, pediatric-, and adult-type patients, respectively. This study analyzed MR imaging data from 10 patients each of fetal, pediatric, and adult types of chronic MeHg poisoning in Minamata and corresponding 53, 37, and 15 age- and sex-matched healthy volunteers. Whole-brain voxel-based morphometry (VBM) analysis was used to determine the volumetric gray and white matter (GM and WM) differences in patients with chronic MeHg poisoning. Compared to healthy individuals, VBM revealed a significant reduction in GM in the cerebellar and calcarine areas in pediatric- and adult-type cases and in the thalamus of fetal-type cases. A significant reduction in WM volume was also noted in the cerebral and the cerebellar regions, especially in pediatric-type cases. Patients with chronic MeHg poisoning develop structural differences in the GM of the calcarine, the cerebellum, and the thalamus and in the WM of the cerebrum and cerebellum. These changes can appear, depending on the timing of MeHg exposure.

Performance of Machine Learning Methods Based on Multi-Sequence Textural Parameters Using Magnetic Resonance Imaging and Clinical Information to Differentiate Malignant and Benign Soft Tissue Tumors.

RATIONALE AND OBJECTIVES: To evaluate the performance of a machine learning method to differentiate malignant from benign soft tissue tumors based on textural features on multiparametric magnetic resonance imaging (mpMRI). MATERIALS AND METHODS: We enrolled 163 patients with soft tissue tumors whose diagnosis was pathologically proven (71 malignant, 92 benign). All patients underwent mpMRI. Twelve histographic and textural parameters were assessed on T1-weighted imaging (T1WI), T2-weighted imaging, diffusion-weighted imaging, apparent diffusion coefficient maps, and contrast-enhanced T1WI imaging. We compared mean signals of all sequences from the malignant and benign tumors using Welch's t-test. Prediction models were developed via a machine learning technique (support vector machine) using textural features of each sequence, clinical information (sex + age + tumor size), and the combined model incorporating all features. Areas under the receiver operating characteristic curves (AUCs) of these models were calculated using fivefold cross validation. RESULTS: The diagnostic ability of clinical information model (AUC 0.85) was not inferior to the model with textural features of each sequence (AUC 0.79-0.84). The combined model showed the highest diagnostic ability (AUC 0.89). The AUC of the combined model (0.89) was comparable to those of two board-certified radiologists (0.89 and 0.87). CONCLUSIONS: Machine learning methods based on textural features on mpMRI and clinical information offer adequate diagnostic performance to differentiate between malignant and benign soft tissue tumors.

Proposed System for Selection of Surgical Approaches for Craniopharyngiomas Based on the Optic Recess Displacement Pattern.

OBJECTIVE: Craniopharyngiomas remain surgically challenging because of the strong adhesion to vital neurovascular structures. We propose a system for the selection of surgical approaches based on the optic recess (OR) displacement pattern to facilitate surgical planning and obtain optimum visual and endocrinologic outcomes. METHODS: Craniopharyngiomas were divided into 3 types based on the OR displacement pattern: superior, anterior, and involvement types. Selected surgical approaches and patient outcome were retrospectively reviewed according to these classifications. Visual and endocrinologic outcomes were compared among the groups. RESULTS: This study included 26 patients with primary craniopharyngiomas who underwent surgery at our institution, classified into 11 anterior, 11 superior, and 4 involvement types. The extended endoscopic endonasal approach provided excellent exposure inferodorsal aspect of the chiasm for manipulation of the dissection plane in the anterior and superior types with midline location. A unilateral subfrontal approach was required for tumor of the superior type with lateral extension. An interhemispheric translamina terminalis approach could provide safe dissection under direct vision of strong adhesion at the superior aspect of the chiasm in the involvement type. Visual and endocrinologic outcomes were better in the involvement type compared with the superior and anterior types. Visual outcome was significantly correlated with preoperative visual function. CONCLUSIONS: Craniopharyngiomas with the involvement type are indicated for the translamina terminalis approach to achieve the best visual and endocrinologic outcome. Our classification of the OR displacement pattern is useful to select the optimal surgical approach for craniopharyngiomas more accurately and concisely, especially in cases with third ventricular extension.

Novel Mathematical Diagnostic Analysis of Malignant Biliary Stenosis Using Magnetic Resonance Cholangiography in Patients Undergoing Pancreaticoduodenectomy.

BACKGROUND/AIM: A novel mathematical diagnostic analysis using Fourier transform (FT) algorithm of the extrahepatic bile duct (BD) using magnetic resonance-cholangiography (MRC) was performed to evaluate irregularities of the bile duct lumen indicating BD cancer (BDC) extension compared to pancreatic head malignancies controls. PATIENTS AND METHODS: BD lumen was automatically traced, and a 2D-diagram cross-section was measured and a FT-based integrated-power-spectral-density-function value (FTV) of both diameter and area (mm 2  and mm 4 /Hz) was calculated for cancerous and non-cancerous parts utilizing a computer workstation. RESULTS: FT analysis that was achieved in 59 patients consisted of BDC in 31, pancreatic cancer with biliary stenosis (PC) in 10 and pancreatic neoplasm without stenosis (PN) in 18. FTV-diameter and -area of non-tumorous proximal BD were larger compared to tumor involving BD (p<0.01), and those of the entire BD in BDCs were significantly larger than those in PN (p<0.01). FTV-diameter and -area in proximal BDC-positive were smaller than those in BDC-negative (p<0.05). BDC part was significantly discriminated by the cutoff value (286 mm 2 Hz -1  in diameter and 10,311 mm 4 Hz -1 in area) compared to PC and diagnostic accuracy was over 70% (p<0.01). CONCLUSION: Novel mathematical MRC FT-analysis is promising for differentiating between BDC and PC with biliary stenosis and can be utilized as an objective diagnostic tool in the future.

Echo planar imaging with compressed sensitivity encoding (EPICS): Usefulness for head and neck diffusion-weighted MRI.

PURPOSE: To evaluate diffusion-weighted imaging (DWI) using echo planar imaging (EPI) with compressed SENSE (EPICS) of the head and neck magnetic resonance imaging (MRI). METHOD: We retrospectively observed 32 patients who underwent head and neck DWI according to either the conventional method (SENSE, reduction factor = 2), fast scanning method (SENSE, reduction factor = 4), or fast scanning method with EPICS (EPICS, reduction factor = 4). For quantitative analysis, contrast-to-noise-ratio (CNR), apparent diffusion coefficient (ADC) values, geometric distortion, and coefficient of variations (CV) were measured and compared. For qualitative analysis, all images were independently and blindly evaluated by two board-certified radiologists. RESULTS: EPICS revealed the higher CNR between all location compared to those of SENSE with reduction factor = 4. Distortion in the anterior-posterior direction was significantly lower on EPICS than on the conventional scan (p = 0.02). A comparison between the ADC values of the EPICS and conventional scan revealed no significant differences. The CV was significantly lower for EPICS than the conventional scan [DWI: 0.22 (IQR: 0.15-0.30) vs 0.32 (IQR: 0.24-0.40), p = 0.02]. CONCLUSIONS: Compressed SENSE combined with the high acceleration factor can improve image quality, homogeneity, and distortion in the head and neck DWI maintaining ADC values and the scan time duration.

T2-fluid-attenuated inversion recovery mismatch sign in lower grade gliomas: correlation with pathological and molecular findings.

After the new molecular-based classification was reported to be useful for predicting prognosis, the T2-fluid-attenuated inversion recovery (FLAIR) mismatch sign has gained interest as one of the promising methods for detecting lower grade gliomas (LGGs) with isocitrate dehydrogenase (IDH) mutations and chromosome 1p/19q non-codeletion (IDH mut-Noncodel) with high specificity. Although all institutions could use T2-FLAIR mismatch sign without any obstacles, this sign was not completely helpful because of its low sensitivity. In this study, we attempted to uncover the mechanism of T2-FLAIR mismatch sign for clarifying the cause of this sign's low sensitivity. Among 99 patients with LGGs, 22 were T2-FLAIR mismatch sign-positive (22%), and this sign as a marker of IDH mut-Noncodel showed a sensitivity of 55.6% and specificity of 96.8%. Via pathological analyses, we could provide evidence that not only microcystic changes but the enlarged intercellular space was associated with T2-FLAIR mismatch sign (p = 0.017). As per the molecular analyses, overexpression of mTOR-related genes (m-TOR, RICTOR) were detected as the molecular events correlated with T2-FLAIR mismatch sign (p = 0.020, 0.030. respectively). Taken together, we suggested that T2-FLAIR mismatch sign could pick up the IDH mut-Noncodel LGGs with enlarged intercellular space or that with overexpression of mTOR-related genes.

Hybrid deep-learning-based denoising method for compressed sensing in pituitary MRI: comparison with the conventional wavelet-based denoising method.

OBJECTIVES: This study aimed to evaluate the efficacy of a combined wavelet and deep-learning reconstruction (DLR) method for under-sampled pituitary MRI. METHODS: This retrospective study included 28 consecutive patients who underwent under-sampled pituitary T2-weighted images (T2WI). Images were reconstructed using either the conventional wavelet denoising method (wavelet method) or the wavelet and DLR methods combined (hybrid DLR method) at five denoising levels. The signal-to-noise ratio (SNR) of the CSF, hypothalamic, and pituitary images and the contrast between structures were compared between the two image types. Noise quality, contrast, sharpness, artifacts, and overall image quality were evaluated by two board-certified radiologists. The quantitative and the qualitative analyses were performed with robust two-way repeated analyses of variance. RESULTS: Using the hybrid DLR method, the SNR of the CSF progressively increased as denoising levels increased. By contrast, with the wavelet method, the SNR of the CSF, hypothalamus, and pituitary did not increase at higher denoising levels. There was a significant main effect of denoising methods (p < 0.001) and denoising levels (p < 0.001), and an interaction between denoising methods and denoising levels (p < 0.001). For all five qualitative scores, there was a significant main effect of denoising methods (p < 0.001) and an interaction between denoising methods and denoising levels (p < 0.001). CONCLUSIONS: The hybrid DLR method can provide higher image quality for T2WI of the pituitary with compressed sensing (CS) than the wavelet method alone, especially at higher denoising levels. KEY POINTS: • The signal-to-noise ratios of cerebrospinal fluid progressively increased with the hybrid DLR method, with an increase in the denoising level for cerebrospinal fluid in pituitary T2WI with CS. • The signal-to-noise ratios of cerebrospinal fluid using the conventional wavelet method did not increase at higher denoising levels. • All qualitative scores of hybrid deep-learning reconstructions at all denoising levels were higher than those for the wavelet denoising method.

Virtual Noncontrast Images Derived From Contrast-Enhanced Dual-Layer Spectral Abdominal Computed Tomography: A Pilot Study Between Pediatric and Adult Scans.

OBJECTIVE: We aimed to compare the accuracy of virtual noncontrast (VNC) images obtained from contrast-enhanced dual-layer spectral computed tomography (DLSCT) scans of the abdomen between pediatric and adult patients. METHODS: We retrospectively studied 10 pediatric and 40 adult patients who underwent unenhanced and contrast-enhanced DLSCT for nontraumatic acute abdomen or a follow-up of tumor or aneurysm. On true noncontrast (TNC) and VNC images, we placed a region-of-interest on 7 abdominal structures. The mean attenuation difference between VNC and TNC images was compared between these structures and between pediatric and adult scans. Data were analyzed by using the Wilcoxon signed-rank test, 1-way analysis of variance, Scheffe's test and independent t test. A P value less than 0.05 was considered statistically significant. RESULTS: In mean attenuation difference between VNC and TNC images, there was a significant interstructure difference in adult scans (P < 0.05), but not in pediatric scans. Mean attenuation difference between VNC and TNC images of the kidney was significantly higher on adult than pediatric scans (P = 0.0046). CONCLUSIONS: The VNC images obtained from contrast-enhanced DLSCT data may be more accurate on pediatric than adult scans. Patient age can be a factor influencing the accuracy of the VNC images.

Spectral imaging with dual-layer spectral detector computed tomography for the detection of perfusion defects in acute coronary syndrome.

To evaluate the feasibility of spectral imaging with dual-layer spectral detector computed tomography (CT) for the diagnosis of acute coronary syndrome. We identified 30 consecutive patients who underwent cardiac CT using dual-layer spectral detector CT and were diagnosed with acute ischemic syndrome by an invasive coronary angiography. We reconstructed 120 kVp images and generated virtual monochromatic images (VMIs; 40-200 keV in 10 keV increments), iodine concentration maps, and effective atomic number (Z) maps. We calculated the contrast and contrast-to-noise ratio (CNR) between myocardial normal and hypo-perfusion and chose the VMIs with the best CNR for quantitative analysis. We compared the image noise, contrast, and CNR of 120 kVp images and the best VMIs, CT value, iodine concentration, and effective Z between myocardial normal and hypo-perfusion with the paired t test. As the X-ray energy decreased, venous attenuation, contrast, and CNR gradually increased. The 40 keV image yielded the best CNR. The contrast and CNR between myocardial normal and hypo-perfusion were significantly higher in 40 keV images than those in 120 kVp images. The iodine concentration and the effective Z were significantly higher in normal myocardium than those in hypo-perfused myocardium. Spectral imaging with dual-layer spectral detector CT is a feasible technique to detect the hypo-perfused area of acute ischemic syndrome.

Detection of acute rib fractures on CT images with convolutional neural networks: effect of location and type of fracture and reader's experience.

PURPOSE: The evaluation of all ribs on thin-slice CT images is time consuming and it can be difficult to accurately assess the location and type of rib fracture in an emergency. The aim of our study was to develop and validate a convolutional neural network (CNN) algorithm for the detection of acute rib fractures on thoracic CT images and to investigate the effect of the CNN algorithm on radiologists' performance. METHODS: The dataset for development of a CNN consisted of 539 thoracic CT scans with 4906 acute rib fractures. A three-dimensional faster region-based CNN was trained and evaluated by using tenfold cross-validation. For an observer performance study to investigate the effect of CNN outputs on radiologists' performance, 30 thoracic CT scans (28 scans with 90 acute rib fractures and 2 without rib fractures) which were not included in the development dataset were used. Observer performance study involved eight radiologists who evaluated CT images first without and second with CNN outputs. The diagnostic performance was assessed by using figure of merit (FOM) values obtained from the jackknife free-response receiver operating characteristic (JAFROC) analysis. RESULTS: When radiologists used the CNN output for detection of rib fractures, the mean FOM value significantly increased for all readers (0.759 to 0.819, P = 0.0004) and for displaced (0.925 to 0.995, P = 0.0028) and non-displaced fractures (0.678 to 0.732, P = 0.0116). At all rib levels except for the 1st and 12th ribs, the radiologists' true-positive fraction of the detection became significantly increased by using the CNN outputs. CONCLUSION: The CNN specialized for the detection of acute rib fractures on CT images can improve the radiologists' diagnostic performance regardless of the type of fractures and reader's experience. Further studies are needed to clarify the usefulness of the CNN for the detection of acute rib fractures on CT images in actual clinical practice.

Usefulness of Virtual Monochromatic Images and Iodine Maps Derived from Dual-Energy Computed Tomography for Diagnosing Deep Neck Abscesses.

OBJECTIVE: We aimed to determine whether dual-energy computed tomography (CT) is useful for evaluating deep neck abscesses. METHODS: This study included 22 consecutive patients who were clinically suspected of having a deep neck abscess and underwent dual-energy CT. Conventional 120-kVp images, 70- and 40-keV virtual monochromatic images (VMIs), and iodine maps were inspected to calculate the contrast ratio of the abscess rim (AR) to the abscess center (AC) or to the adjacent muscle (M). The diagnostic certainty of abscesses was assessed on these images. RESULTS: Twenty (91%) of 22 patients had a definitive diagnosis. The contrast ratio for AR/AC and AR/M was significantly higher on 40-keV VMIs and iodine maps than on 120-kVp images and 70-keV VMIs (P < 0.05). On both 40-keV VMIs and iodine maps, the diagnostic certainty of abscess improved in 3 (15%) cases compared with 120-kVp images and 70-keV VMIs. CONCLUSIONS: Dual-energy CT-based 40-keV VMIs and iodine maps are useful for evaluating deep neck abscesses and may improve diagnostic certainty.