A preliminary study of super-resolution deep learning reconstruction with cardiac option for evaluation of endovascular-treated intracranial aneurysms.

OBJECTIVES: To investigate the usefulness of super-resolution deep learning reconstruction (SR-DLR) with cardiac option in the assessment of image quality in patients with stent-assisted coil embolization, coil embolization, and flow-diverting stent placement compared with other image reconstructions. METHODS: This single-centre retrospective study included 50 patients (mean age, 59 years; range, 44-81 years; 13 men) who were treated with stent-assisted coil embolization, coil embolization, and flow-diverting stent placement between January and July 2023. The images were reconstructed using filtered back projection (FBP), hybrid iterative reconstruction (IR), and SR-DLR. The objective image analysis included image noise in the Hounsfield unit (HU), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and full width at half maximum (FWHM). Subjectively, two radiologists evaluated the overall image quality for the visualization of the flow-diverting stent, coil, and stent. RESULTS: The image noise in HU in SR-DLR was 6.99 ± 1.49, which was significantly lower than that in images reconstructed with FBP (12.32 ± 3.01) and hybrid IR (8.63 ± 2.12) (P < .001). Both the mean SNR and CNR were significantly higher in SR-DLR than in FBP and hybrid IR (P < .001 and P < .001). The FWHMs for the stent (P < .004), flow-diverting stent (P < .001), and coil (P < .001) were significantly lower in SR-DLR than in FBP and hybrid IR. The subjective visual scores were significantly higher in SR-DLR than in other image reconstructions (P < .001). CONCLUSIONS: SR-DLR with cardiac option is useful for follow-up imaging in stent-assisted coil embolization and flow-diverting stent placement in terms of lower image noise, higher SNR and CNR, superior subjective image analysis, and less blooming artifact than other image reconstructions. ADVANCES IN KNOWLEDGE: SR-DLR with cardiac option allows better visualization of the peripheral and smaller cerebral arteries. SR-DLR with cardiac option can be beneficial for CT imaging of stent-assisted coil embolization and flow-diverting stent.

Assessment of Image Quality of Coronary CT Angiography Using Deep Learning-Based CT Reconstruction: Phantom and Patient Studies.

BACKGROUND: In coronary computed tomography angiography (CCTA), the main issue of image quality is noise in obese patients, blooming artifacts due to calcium and stents, high-risk coronary plaques, and radiation exposure to patients. OBJECTIVE: To compare the CCTA image quality of deep learning-based reconstruction (DLR) with that of filtered back projection (FBP) and iterative reconstruction (IR). METHODS: This was a phantom study of 90 patients who underwent CCTA. CCTA images were acquired using FBP, IR, and DLR. In the phantom study, the aortic root and the left main coronary artery in the chest phantom were simulated using a needleless syringe. The patients were classified into three groups according to their body mass index. Noise, the signal-to-noise ratio (SNR), and the contrast-to-noise ratio (CNR) were measured for image quantification. A subjective analysis was also performed for FBP, IR, and DLR. RESULTS: According to the phantom study, DLR reduced noise by 59.8% compared to FBP and increased SNR and CNR by 121.4% and 123.6%, respectively. In a patient study, DLR reduced noise compared to FBP and IR. Furthermore, DLR increased the SNR and CNR more than FBP and IR. In terms of subjective scores, DLR was higher than FBP and IR. CONCLUSION: In both phantom and patient studies, DLR effectively reduced image noise and improved SNR and CNR. Therefore, the DLR may be useful for CCTA examinations.

Coronary artery calcium quantification: comparison between filtered-back projection, hybrid iterative reconstruction, and deep learning reconstruction techniques.

BACKGROUND: The reference protocol for the quantification of coronary artery calcium (CAC) should be updated to meet the standards of modern imaging techniques. PURPOSE: To assess the influence of filtered-back projection (FBP), hybrid iterative reconstruction (IR), and three levels of deep learning reconstruction (DLR) on CAC quantification on both in vitro and in vivo studies. MATERIAL AND METHODS: In vitro study was performed with a multipurpose anthropomorphic chest phantom and small pieces of bones. The real volume of each piece was measured using the water displacement method. In the in vivo study, 100 patients (84 men; mean age = 71.2 ± 8.7 years) underwent CAC scoring with a tube voltage of 120 kVp and image thickness of 3 mm. The image reconstruction was done with FBP, hybrid IR, and three levels of DLR including mild (DLRmild), standard (DLRstd), and strong (DLRstr). RESULTS: In the in vitro study, the calcium volume was equivalent (P = 0.949) among FBP, hybrid IR, DLRmild, DLRstd, and DLRstr. In the in vivo study, the image noise was significantly lower in images that used DLRstr-based reconstruction, when compared images other reconstructions (P < 0.001). There were no significant differences in the calcium volume (P = 0.987) and Agatston score (P = 0.991) among FBP, hybrid IR, DLRmild, DLRstd, and DLRstr. The highest overall agreement of Agatston scores was found in the DLR groups (98%) and hybrid IR (95%) when compared to standard FBP reconstruction. CONCLUSION: The DLRstr presented the lowest bias of agreement in the Agatston scores and is recommended for the accurate quantification of CAC.

The effectiveness of post-processing head and neck CT angiography using contrast enhancement boost technique.

BACKGROUND AND PURPOSE: This study aimed to investigate the potential of contrast enhancement (CE)-boost technique in the head and neck computed tomography (CT) angiography in terms of the objective and subjective image quality. MATERIALS AND METHODS: Consecutive patients who underwent head and neck CT angiography between May 2022 and July 2022 were included. The CE-boost images were generated by combining the subtracted iodinated image and contrast-enhanced image. The objective image analysis was compared for each image with and without CE-boost technique using the CT attenuation, image noise, signal-to-noise-ratio (SNR), contrast-to-noise-ratio (CNR), and image sharpness (full width at half width maximum, FWHM). The subjective image analysis was evaluated by two independent experienced radiologists in the following aspects: the overall image quality, motion artifact, vascular delineation, and vessel sharpness. RESULTS: A total of 65 patients (mean age, 59.48 ± 13.71 years; range, 24-87 years; 36 women) were included. The CT attenuation of the vertebrobasilar arteries was significantly (p < 0.001) higher in the images obtained using CE-boost technique than in conventional images. Image noise was significantly (p < 0.001) lower for CE-boost images (6.09 ± 1.93) than for conventional images (7.79 ± 1.73). Moreover, CE-boost technique yielded higher SNR (64.43 ± 17.17 vs. 121.37 ± 38.77, p < 0.001) and CNR (56.90 ± 18.79 vs. 116.65 ± 57.44, p < 0.001) than conventional images. CE-boost resulted in shorter FWHM than conventional images (p < 0.001). Higher subjective image quality scores were also demonstrated by the CE-boost than images without CE-boost technique. CONCLUSIONS: In both objective and subjective image analysis, the CE-boost technique provided higher image quality without increasing the flow rate and concentration of contrast media in the head and neck CT angiography. Furthermore, the vessel completeness and delineation were superior in CE-boost images than in conventional images.

A Novel Computed Tomography Image Reconstruction for Improving Visualization of Pulmonary Vasculature: Comparison Between Preprocessing and Postprocessing Images Using a Contrast Enhancement Boost Technique.

OBJECTIVE: This study aimed to evaluate chest computed tomography (CT) angiography image quality using the contrast enhancement (CE)-boost technique compared with conventional images. METHODS: Forty patients who underwent contrast-enhanced chest CT were included. Combined CT angiography images of the iodinated image obtained from the subtraction of nonenhanced CT images and CT angiography images were used to generate CE-boost images. Computed tomography attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) for the right and left pulmonary arteries as the central and subsegmental arteries as peripheral vessels were assessed. Subjective image quality was rated on a 5-point scale by 2 radiologists. Image quality was assessed using a paired t test. RESULTS: Computed tomography attenuation in the main pulmonary artery was significantly higher for the CE-boost images (311.05 ± 91.94) than for the conventional images (221.25 ± 61.21, P < 0.001). Similarly, the CE-boost images resulted in significantly higher CT attenuation in the subsegmental arteries (right, 305.34 ± 90.13; left, 313.05 ± 97.21) than in the conventional images (right, 218.45 ± 63.16; left, 223.89 ± 74.27). The CE-boost technique demonstrated marked improvement in the visualization of the peripheral pulmonary artery without the administration of a higher iodine delivery rate. The mean SNR and CNR were also significantly higher in the central and peripheral vessels in the CE-boost images than in the conventional images (P < 0.001). In the subjective analysis, the image contrast and vascular contrast edge were significantly higher for the CE-boost images than for conventional images (P < 0.001). CONCLUSIONS: The CE-boost technique increases not only the visualization of peripheral arteries by improving vascular attenuation but also the SNR and CNR.

Symptomatic bilateral massive pulmonary embolism and proximal and distal deep vein thrombosis following arthroscopic meniscus surgery: A case report.

RATIONALE: The incidence of venous thromboembolism (VTE) after knee arthroscopy is remarkably lower than that of arthroplasty. We describe a patient with symptomatic bilateral massive pulmonary thromboembolism (PTE) and deep vein thrombosis (DVT) in the femoral and popliteal veins after arthroscopic meniscus repair surgery. PATIENT CONCERNS: The patient underwent arthroscopic meniscus repair with no intraoperative complication. There were no underlying diseases such as hypertension or diabetes. On day 5 postoperative, the patient complained of dyspnea, chest discomfort, and nausea after standing. DIAGNOSIS: On DVT and PTE computed tomography, there were multifocal PTEs in the distal portion of the main and segmental branches of both pulmonary arteries. There was a focal thrombosis in the left deep femoral vein, as well as small DVTs in the left popliteal and calf veins. INTERVENTIONS: After 3 days of low-molecular-weight heparin 1 mg/kg every 12 hours, treatment was changed to an oral drug, dabigatran, for 6 months. OUTCOMES: There were no PTE or DVT findings on computed tomography at 6 months postoperative. The patient did not complain of symptoms related to PTE or DVT at 6 months after the operation, has returned to work, and is living without discomfort. LESSIONS: The frequency of VTE is very low after arthroscopic meniscus surgery, but it represents a life-threatening event. Our patient had risk factors for VTE including obesity, surgery time of ∼60 minutes, and immobilization. Although arthroscopic meniscus surgery is relatively safe, evaluation of risk factors for VTE should be performed before and after surgery, and appropriate thromboprophylaxis should be provided when necessary.

Association of bone mineral density with the development of knee osteoarthritis in men and women: a cross-sectional study using the fourth and fifth Korea National Health and Nutrition Examination Surveys.

Bone mineral density (BMD) and osteoarthritis (OA) were correlated but the relationship was varied according to sex. An association between lumbar spine and femur neck BMDs and OA showed a positive relation in women, while lumbar spine and pelvis BMDs in men were associated with OA with a negative relation. PURPOSE: The purpose of this study was to evaluate the association of BMD in various body parts in conjunction with the presence or severity of radiographic knee osteoarthritis (KOA) in relation to sex. METHODS: This study was a cross-sectional analysis using Korea National Health and Nutrition Examination Surveys. KOA was graded using the Kellgren-Lawrence (KL) grading system. Radiographic KOA was defined as a KL grade 2 or higher. The associations between KOA and BMD in certain body parts (femur, pelvis, lumbar, lower leg, and whole-body) were assessed. BMD was measured using dual-energy X-ray absorptiometry. The BMD of each body part was divided into quartiles and the relationship between KOA and BMD was examined according to sex. RESULTS: BMD did not show a significant tendency according to KL grade in either sex. In men, the severity of KL grade have a statistically significant relationship with total femur (R2 = 0.303, p < 0.05), femur neck (R2 = 0.257, p < 0.05), lumbar (R2 = 0.137, p < 0.05), and pelvis BMD (R2 = 0.185, p < 0.05). In women, total femur (R2 = 0.466, p < 0.05), lumbar (R2 = 0.316, p < 0.05), pelvis (R2 = 0.343, p < 0.05), and lower leg BMD (R2 = 0.133, p < 0.05) were associated with the severity of KL grade. When the BMD was divided into quartiles, lumbar (p < 0.05) and pelvis BMD (p < 0.05) in men had statistically significant association with knee OA as BMD decreased. In women, femur neck (p < 0.05) and lumbar BMD (p < 0.05) were significantly associated with knee OA as BMD increased. CONCLUSION: The relationship between BMD and OA severity varied according to sex. In women, there was a positive association between femur neck and lumbar BMD and OA, while BMD of the lumbar and pelvis in men was negatively correlated with OA. LEVEL OF EVIDENCE: Cohort study, III.

Efficient synthesis of individual single-walled carbon nanotube by water-based catalyst with poly(vinylpyrrolidone).

Individual single-walled carbon nanotubes (SWCNTs) were synthesized on the patterned water-soluble catalyst by thermal chemical vapor deposition. The individual SWCNTs were obtained by introducing polyvinylpyrrolidone (PVP) as a dispersant. The number of SWCNTs between two electrodes were approximately 1-2 with an average diameter of about 1.7 nm and a yield of forming electrodes of nearly 70%. The PVP played an important role in dispersing catalysts and suppressing the active sites to limit the number of SWCNTs during synthesis, which is a critical condition for fabrication of field effect transistors (FETs). The measured I-V characteristics of the over layer-deposited electrodes revealed a clear gating effect in large portion, in good agreement with Raman observations in several excitation energies. The patterning procedure, catalyst preparation, and growth condition for fabrication of the SWCNT-FET were further discussed.