Correction to: Effect of training on ultrasonography (US) BI-RADS features for radiology residents: a multicenter study comparing performances after training.

The original version of this article, published on 07 January 2019, unfortunately contained a mistake.

Effect of training on ultrasonography (US) BI-RADS features for radiology residents: a multicenter study comparing performances after training.

OBJECTIVES: To evaluate the effect of training radiology residents on breast ultrasonography (US) according to the Breast Imaging Reporting And Data System (BI-RADS) and the factors that influence the training effect. METHODS: This multicenter, prospective study was approved by eight institutional review boards. From September 2013 to July 2014, 248 breast masses in 227 women were included for US image acquisition. Representative B-mode and video images of the breast masses were recorded, among which 54 cases were included in the education set and 66 in the test set. Sixty-one radiology residents scheduled for breast imaging training individually reviewed the test set, immediately before, 1 month after, and 6 months after training. Diagnostic performances and US descriptors of the residents were evaluated and compared against those of expert radiologists. RESULTS: Agreements between residents and experienced radiologists showed improvement after training, while agreements between post-training and post-6-month training descriptors did not show significant differences (all p > 0.05, respectively). Sensitivity, negative predictive value (NPV), and AUC were significantly improved for residents post-training and post-6-month training (all p < 0.05), while approximating the performances of expert radiologists except for AUC (0.836, 0.840, and 0.908, respectively, p < 0.05). Low levels of pre-training AUC, total number of breast US examinations, and the number of sessions per week that residents were involved in were factors influencing the improvement of AUC. CONCLUSION: Training using education material dedicated for breast US imaging effectively improved the diagnostic performances of radiology residents and agreements with experienced radiologists on US BI-RADS features. KEY POINTS: • Agreements on lesion descriptors between residents and experienced radiologists showed improvement after training, regardless of test point. • Sensitivity, NPV, and AUC were significantly improved for residents in post-training and post-6-month training (all p < 0.05). • Low levels of pre-training AUC, total number of breast US examinations, and the number of sessions per week that residents were involved in were factors influencing the improvement of AUC.

Comparison of the SRmax, SRave, and color map of strain-elastography in differentiating malignant from benign breast lesions.

BACKGROUND: The maximum value of the strain ratio (SR) is a newly developed measure in strain-elastography. PURPOSE: To prospectively compare the diagnostic performance of three different measures of strain-elastography, the maximum value of the SR (SRmax), the average value of the SR (SRave), and the color map, for differentiating benign and malignant breast lesions. MATERIAL AND METHODS: We obtained the SRmax and SRave of 314 lesions from 290 patients with the tissue to nodule SR and color map using a five-degree scoring system. The diagnostic performances of the SRmax, SRave, and color map were compared after obtaining the area under the receiver operating characteristic (ROC) curves (AUCs) of each parameter. RESULTS: The AUC of the SRmax (0.7674) was larger than the AUCs of the SRave (0.7138) and color map (0.6324), with statistical significance ( P = 0.0383 for SRmax vs. SRave, P = 0.0000 for SRmax vs. color map). The AUC of the SRave was larger than that of the color map; however, there was no significant difference. The optimal cut-off point of the SRmax that balanced the sensitivity (91.12%) and specificity (50.81%) was 5.16. CONCLUSION: The SRmax is a more reliable diagnostic tool than the SRave and color map for differentiating benign and malignant breast lesions.

Real-time detection system for tumor localization during minimally invasive surgery for gastric and colon cancer removal: In vivo feasibility study in a swine model.

BACKGROUND AND OBJECTIVES: During minimally invasive surgery (MIS), it is impossible to directly detect marked clips around tumors via palpation. Therefore, we developed a novel method and device using Radio Frequency IDentification (RFID) technology to detect the position of clips during minimally invasive gastrectomy or colectomy. METHODS: The feasibility of the RFID-based detection system was evaluated in an animal experiment consisting of seven swine. The primary outcome was to successfully detect the location of RFID clips in the stomach and colon. The secondary outcome measures were to detect time (time during the intracorporeal detection of the RFID clip), and accuracy (distance between the RFID clip and the detected site). RESULTS: A total of 25 detection attempts (14 in the stomach and 11 in the colon) using the RFID antenna had a 100% success rate. The median detection time was 32.5 s (range, 15-119 s) for the stomach and 28.0 s (range, 8-87 s) for the colon. The median detection distance was 6.5 mm (range, 4-18 mm) for the stomach and 6.0 mm (range, 3-13 mm) for the colon. CONCLUSIONS: We demonstrated favorable results for a RFID system that detects the position of gastric and colon tumors in real-time during MIS.

Impact of region of interest (ROI) size on the diagnostic performance of shear wave elastography in differentiating solid breast lesions.

Background Shear wave elastography (SWE) using a region of interest (ROI) can demonstrate the quantitative elasticity of breast lesions. Purpose To prospectively evaluate the impact of two different ROI sizes on the diagnostic performance of SWE for differentiating benign and malignant breast lesions. Material and Methods A total of 154 breast lesions were included. Two types of ROIs were investigated: one involving an approximately 2-mm diameter, small round ROIs placed over the stiffest area of the lesion, as determined by SWE (ROI-S); and another ROI drawn along the margin of the lesion using a touch pen or track ball to encompass the entire lesion (ROI-M). Maximum elasticity (Emax), mean elasticity (Emean), minimum elasticity (Emin), and standard deviation (SD) were measured for the two ROIs. The area under the receiver operating characteristic curve (AUC) as well as the sensitivity and specificity of each elasticity value were determined. Results The AUCs for ROI-S were higher than those for ROI-M when differentiating benign and malignant breast solid lesions. The Emax, Emean, Emin, and SD of the elasticity values for ROI-S were 0.865, 0.857, 0.816, and 0.849, respectively, and for ROI-M were 0.820, 0.780, 0.724, and 0.837, respectively. However, only Emax ( P = 0.0024) and Emean ( P = 0.0015) showed statistically significant differences. For ROI-S, the sensitivity and specificity of Emax were 78.8% and 84.3%, respectively, and those for Emean were 80.8% and 81.4%, respectively. Conclusion Using ROI-S with Emax and Emean has better diagnostic performance than ROI-M for differentiating between benign and malignant breast lesions.

The role of US in finding intussusception and alternative diagnosis: a report of 100 pediatric cases.

BACKGROUND: The clinical diagnosis of intussusception remains challenging, because many children with intussusception may present with non-specific signs and symptoms, which overlap with other conditions. Therefore imaging, in particular ultrasonography (US), plays a significant role in the management of these patients. PURPOSE: To evaluate how US can contribute to the diagnosis in clinically suspected intussusception and finding alternative diagnosis. MATERIAL AND METHODS: We retrospectively reviewed reports of US examinations and medical records of 100 patients (51 boys, 49 girls; mean age, 23.0 ± 12.1 months) who underwent abdominal US for clinically suspected intussusception. Each US study was assessed for the presence or absence of intussusception and for a possible alternative diagnosis in cases interpreted as negative for intussusception. RESULTS: Thirty-seven patients had US findings consistent with intussusception, which was confirmed by air enema. In seven patients, US studies were normal. Alternative diagnoses were identified by US for each of the remaining 56 patients, including ileocolitis (n = 20), terminal ileitis (n = 18), mesenteric lymphadenitis (n = 13), choledochal cyst (n = 1), accessory spleen torsion (n = 1), small bowel ileus (n = 1), midgut volvulus with bowel ischemia (n = 1), and hydronephrosis (n = 1). CONCLUSION: With the high sensitivity and specificity of this study we conclude that US is valuable in detecting intussusception and finding the alternative diagnosis.

Digital breast tomosynthesis versus full-field digital mammography: comparison of the accuracy of lesion measurement and characterization using specimens.

BACKGROUND: Digital breast tomosynthesis (DBT) is one of the new techniques being developed to overcome the inherent limitations of mammography caused by superimposed structures in a 2D projection. PURPOSE: To compare the diagnostic performances of digital breast tomosynthesis (DBT) and full-field digital mammography (FFDM) for lesion characterization and size measurement using breast specimens. MATERIAL AND METHODS: Out of 156 women scheduled for surgery, we included in our study 114 women, each of whom had a single, breast lesion. Three breast radiologists independently evaluated the DBT and FFDM performance regarding the breast specimens obtained during surgery. Each reader measured the lesion size, and then categorized the probability of malignancy using the American College of Radiology Breast Imaging Reporting and Data system (BI-RADS). After both reading sessions, the readers selected the preferred modality of either FFDM or DBT in lesion characterization. We also analyzed the radiologists' evaluation performance in patients with dense versus fatty breasts when using DBT and FFDM. RESULTS: The imaging findings of 84 cancers and 30 benign lesions, all of which had been pathologically proven, were reviewed. The size evaluation determined by DBT was more accurately correlated with that found by pathology (P = 0.001 for fatty breasts and <0.001 for dense breasts) than that determined by FFDM. The correlation coefficients of DBT and FFDM to the pathologically determined lesion size were 0.90 and 0.89, respectively (P < 0.001). Compared with the pathologically determined lesion size, the size determined by both imaging modalities was overestimated. Overall, assessment of the probability of malignancy by DBT and FFDM did not differ significantly (P = 0.07); however, in dense breast, DBT was more strongly correlated with the pathology determination than FFDM (P = 0.03). CONCLUSION: DBT may be superior to FFDM for determining the preoperative size measurement of breast lesions irregardless of their parenchymal density. Particularly in dense breasts, DBT was more useful for differentiating the lesion malignancy rate.

Radiologic Findings of Polyacrylamide Gel Mammoplasty and Its Complications: A Report of Four Case Series and Review of Literature.

Polyacrylamide gel (PAAG) has been used for augmentation mammoplasty in certain countries, such as China or Eastern European countries. However, owing to various complications, its use is currently banned in most countries. Nevertheless, because of the migratory stream of female from these countries, we also encounter patients with PAAG mammoplasty in Korea. Owing to the various imaging features of PAAG mammoplasty, it may interfere with the identification of malignancy or other pathologic conditions. Therefore, it is important to identify the imaging findings related to PAAG mammoplasty. However, there is limited literature on the radiologic findings of complications related to PAAG mammoplasty in Korea. Herein we report four cases of PAAG mammoplasty, the complications faced, and depict various radiologic features through multimodality imaging.

Children and adolescent patients with goiter and normal thyroid function: US findings related to underlying autoimmune thyroid diseases.

This study was conducted to investigate and compare thyroid ultrasonography (US) findings in children and adolescents with goiter and normal thyroid function with positive or negative thyroid autoimmunity. From 2000 to 2020, we reviewed initial thyroid US images in 33 autoimmune thyroid diseases (AITDs) patients and 52 nonAITD patients. Our review of the images focused on thyroid parenchymal hypoechogenicity and heterogeneous echopattern subdivided into 2 groups according to severity: hypoechogenicity 1 and 2 (HO1 and HO2) and heterogeneity 1 and 2 (HE1 and HE2). HO1 and HE1 were observed more frequently in the nonAITD group (86.5% and 42.3%, respectively), while HO2 and HE2 were observed more frequently in the AITDs group (36.4% and 81.8%, respectively). More patients in the AITDs group showed change of both US groups and thyroid function state within the follow-up periods than in nonAITD group (33.3% and 5.77%, respectively). Children and adolescent AITDs patients showed more severe parenchyma hypoechogenicity and heterogeneous echopattern compared with nonAITD patients with goiter and normal thyroid function.

Supplemental use of optical diffusion breast imaging for differentiation between benign and malignant breast lesions.

OBJECTIVE: The objective of our study was to prospectively evaluate the diagnostic accuracy of optical diffusion breast imaging in patients who underwent conventional ultrasound followed by surgery or biopsy. SUBJECTS AND METHODS: We performed optical diffusion breast imaging after conventional ultrasound of 193 patients (mean age, 47 years) with 217 lesions. All patients underwent ultrasound-guided core needle biopsy or surgery. One of six radiologists reviewed conventional ultrasound features, assessed a BI-RADS category, and reviewed optical diffusion imaging results for each lesion. Surgery and biopsy results were used as reference standards. We compared the diagnostic accuracy including the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of conventional ultrasound alone and of conventional ultrasound followed by optical diffusion imaging. In addition, we prospectively investigated if total hemoglobin level or oxygen saturation level is the most reliable indicator in optical diffusion imaging. RESULTS: Of the 217 breast lesions, 108 were malignant and 109 were benign. For differentiation of malignant from benign lesions, conventional ultrasound was associated with a sensitivity of 100%, specificity of 27.5%, PPV of 57.8%, NPV of 100%, and accuracy of 63.6%. The supplemental use of optical diffusion imaging after conventional ultrasound was associated with a sensitivity of 98.1%, specificity of 41.3%, PPV of 62.4%, NPV of 95.7%, and accuracy of 69.7%. The area under the receiver operating characteristic curve was 0.738 for total hemoglobin level and 0.502 for oxygen saturation level. The cutoff value was 0.195 mmol/L for total hemoglobin, with 68.4% sensitivity and 69.7% specificity. CONCLUSION: Optical diffusion imaging might be a good supplemental tool to increase the diagnostic accuracy of conventional ultrasound in differentiating malignant from benign breast lesions.

The relationship between ultrasound findings and thyroid function in children and adolescent autoimmune diffuse thyroid diseases.

To evaluate the association between thyroid echogenicity and heterogeneity seen on ultrasonography (US) and thyroid function in pediatric and adolescent populations with autoimmune diffuse thyroid diseases (AITD). From 2000 to 2020, we reviewed thyroid ultrasound (US) images and thyroid function statuses in 133 children and adolescent AITD patients. Our review of the images focused on decreased echogenicity and heterogeneity, which were classified into four grades. Among patients with overt hypothyroidism or overt hyperthyroidism, 94.2% (65/69) showed a US grade of 3 or 4. In patients with subclinical hyper/hypothyroidism or euthyroidism, 45.3% (29/64) showed grades 1 or 2. There were no overt hyper/hypothyroidism patients with US grade 1. When we compared US grades according to thyroid status, more severe thyroid dysfunction was significantly associated with higher US grade (p = 0.047). Thyroid stimulating hormone (TSH) level differed significantly according to US grades when we evaluated hyperthyroid (p = 0.035) and hypothyroid (p = 0.027) states independently. 11 patients showed both US grade and thyroid function status changes on follow-up US. In children and adolescent AITD patients, there was an association between decreased echogenicity and heterogeneity on US and thyroid dysfunction.

BI-RADS descriptors for mammographically detected microcalcifications verified by histopathology after needle-localized open breast biopsy.

OBJECTIVE: The objective of our study was to retrospectively determine the positive predictive value of each descriptor and of combined descriptors for microcalcifications to predict the risk of malignancy as well as the appropriate final assessment category. MATERIALS AND METHODS: A total of 308 needle-localized open breast biopsies for mammographically detected microcalcifications were performed in 295 women (age range, 33-71 years; mean age, 52 years) during 7 years. Thirteen patients had bilateral microcalcifications that were studied separately. Two breast radiologists retrospectively reviewed the microcalcifications with regard to their morphology, distribution, and extent and to associated findings and final assessment category, after which they categorized them into nine combined descriptors. Surgical pathology served as the reference standard for malignant lesions and follow-up of at least 12 months served as the reference for benign lesions. The Fisher's exact test, including odds ratios, was used for statistical analysis. RESULTS: Of the 308 needle-localized open breast biopsies, 144 (47%) were malignant and 164 (53%) were benign. For combined descriptors of morphology and distribution, the odds ratios of malignancy regarding the higher probability of malignancy and ductal distribution were as follows: 0 for typically benign morphology or scattered distribution, 93.00 for intermediate concern and regional, 33.53 for intermediate concern and clustered, 5.00 for intermediate concern and ductal, 24.00 for higher probability of malignancy and regional, and 1.13 for higher probability of malignancy and clustered. CONCLUSION: Each descriptor and combined descriptors for microcalcifications and the final assessment category could help to predict the risk of malignancy.

Development of a cold dialysate regeneration system for home hemodialysis.

BACKGROUND/AIMS: Because longer and/or more frequent dialysis has potential clinical benefits, home hemodialysis (HHD) systems should provide flexible renal replacement therapies. We propose a new cold dialysate regeneration system that requires 10 l per treatment for HHD. METHODS: We designed a dialysate regeneration system using cold dialysate and 2 activated carbon columns alternatively switched between adsorption and desorption. Urea adsorption ratios were compared in three different conditions; cold dialysate (5.7 degrees C), normal dialysate (36.8 degrees C), and cold dialysate with washing. In vivo tests (n = 8) were conducted to validate this system. RESULTS: The urea removal ratios were 20.0 +/- 1.7% in cold dialysate, 36.0 +/- 1.7% in normal dialysate, and 82.5 +/- 1.2% in cold dialysate with washing. In animal experiments, the urea reduction ratio was 60.9 +/- 6.3%, Kt/V was 1.0 +/- 0.2, and serum electrolytes remained stable. CONCLUSION: The proposed cold dialysate regeneration system using a small volume of dialysate will be useful for HHD.

Development of an intrafascicular neural interface for peripheral nerve implantation.

This paper describes an intrafascicular neural interface for peripheral nerve implantation. The flexible penetrating microelectrode array with varying lengths (vl-FPMA), interconnection cable, wireless recording and stimulator modules were designed and fabricated to detect neural signals from the peripheral nerves or to stimulate them. The vl-FPMA consisted of silicon needles and polydimethylsiloxane (PDMS) platform supporting the needles. The length of electrode needles varied from 600 to 1000 µm. The interconnection cable was fabricated as parylene-metal-parylene sandwiched structure. The wireless recording/stimulation modules were also developed and connected with the electrodes. The integrated system was implanted in the sciatic nerve of beagles and the recording capability of the integrated system was demonstrated successfully.

Follow-up design of unexpected enhancing lesions on preoperative MRI of breast cancer patients.

PURPOSE: We aimed to analyze the characteristics and long-term follow-up results of unexpected enhancing lesions on preoperative magnetic resonance imaging (MRI) of breast cancer patients. METHODS: From August 2007 through February 2010, second-look ultrasound (SLUS) was recommended for 84 of 312 breast cancer patients having unexpected enhancing lesions on MRI. SLUS was performed for 85 unexpected enhancing lesions in 72 patients. We performed a retrospective review to determine the size, lesion type, enhancement kinetic curve, and location in relation to the index cancer. We obtained the pathologic outcome of the detected lesions and in case of a negative finding on SLUS, we performed follow-up examinations for at least two years. RESULTS: Of 85 unexpected lesions, 72 (85%) were detected on SLUS. In total, 41 lesions (56.9%) were confirmed as malignant and 31 lesions (43.6%) as benign. Cancer rate was statistically higher in lesions having type III enhancement pattern, located at the same quadrant as the index cancer. However, no significant association was observed between the cancer rate and the lesion size and type. None of the 13 negative cases on SLUS developed cancer on follow-up. CONCLUSION: In case of unexpected enhancing lesions on preoperative MRI of breast cancer patients, SLUS can be useful to find out the matched lesion. Lesions with type III enhancement pattern or those located at the same quadrant as the index cancer should be considered as a separate cancer. In the absence of any suspicious findings on SLUS, patient may be followed up with confidence.

Microfluidic spinning of flat alginate fibers with grooves for cell-aligning scaffolds.

Alginate microribbons with longitudinally grooved microstructures are continuously fabricated by means of a microfluidic system. The number and dimensions of the microgroovesare successfully controlled by regulation of the slit-shaped channel (yellow in figure). This method opens up the possibility of mass production of scaffolds for tissue engineering purposes, as it is proved that the grooved flat fibers can be used to align other types of cells in culture.

CNT/PDMS composite flexible dry electrodes for long-term ECG monitoring.

We fabricated a carbon nanotube (CNT)/ polydimethylsiloxane (PDMS) composite-based dry ECG electrode that can be readily connected to conventional ECG devices, and showed its long-term wearable monitoring capability and robustness to motion and sweat. While the dispersion of CNTs in PDMS is challenging, we optimized the process to disperse untreated CNTs within PDMS by mechanical force only. The electrical and mechanical characteristics of the CNT/PDMS electrode were tested according to the concentration of CNTs and its thickness. The performances of ECG electrodes were evaluated by using 36 types of electrodes which were fabricated with different concentrations of CNTs, and with a differing diameter and thickness. The ECG signals were obtained by using electrodes of diverse sizes to observe the effects of motion and sweat, and the proposed electrode was shown to be robust to both factors. The CNT concentration and diameter of the electrodes were critical parameters in obtaining high-quality ECG signals. The electrode was shown to be biocompatible from the cytotoxicity test. A seven-day continuous wearability test showed that the quality of the ECG signal did not degrade over time, and skin reactions such as itching or erythema were not observed. This electrode could be used for the long-term measurement of other electrical biosignals for ubiquitous health monitoring including EMG, EEG, and ERG.

Solderable and electroplatable flexible electronic circuit on a porous stretchable elastomer.

A variety of flexible and stretchable electronics have been reported for use in flexible electronic devices or biomedical applications. The practical and wider application of such flexible electronics has been limited because commercial electronic components are difficult to be directly integrated into flexible stretchable electronics and electroplating is still challenging. Here, we propose a novel method for fabricating flexible and stretchable electronic devices using a porous elastomeric substrate. Pressurized steam was applied to an uncured polydimethylsiloxane layer for the simple and cost-effective production of porous structure. An electroplated nickel anchor had a key role in bonding commercial electronic components on elastomers by soldering techniques, and metals could be stably patterned and electroplated for practical uses. The proposed technology was applied to develop a plaster electrocardiogram dry electrode and multi-channel microelectrodes that could be used as a long-term wearable biosignal monitor and for brain signal monitoring, respectively.

A low-energy-consumption electroactive valveless hydrogel micropump for long-term biomedical applications.

Stimuli-responsive hydrogels have attracted considerable interest in the field of microfluidics due to their ability to transform electrical energy directly into mechanical work through swelling, bending, and other deformations. In particular, electroactive hydrogels hold great promise for biomedical micropumping applications such as implantable drug delivery systems. In such applications, energy consumption rate and durability are key properties. Here, we developed a valveless micropump system that utilizes a hydrogel as the main actuator, and tested its performance over 6 months of continuous operation. The proposed micropump system, powered by a single 1.5 V commercial battery, expended very little energy (less than 750 µWs per stroke) while pumping 0.9 wt% saline solution under a low voltage (less than 1 V), and remained fully functional after 6 months. CFD simulations were conducted to improve the microchannel geometry so as to minimize the backflow caused by the valveless mechanism of the system. Based on the simulation results, an asymmetric geometry and a stop post were introduced to enhance the pumping performance. To demonstrate the feasibility of the proposed system as a drug delivery pump, an anti-cancer drug (adriamycin) was perfused to human breast cancer cells (MCF-7) using the pump. The present study showed that the proposed system can operate continuously for long periods with low energy consumption, powered by a single 1.5 V battery, making it a promising candidate for an implantable drug delivery system.

Interconnection of multichannel polyimide electrodes using anisotropic conductive films (ACFs) for biomedical applications.

In this paper, we propose a method for interconnecting soft polyimide (PI) electrodes using anisotropic conductive films (ACFs). Reliable and automated bonding was achieved through development of a desktop thermocompressive bonding device that could simultaneously deliver appropriate temperatures and pressures to the interconnection area. The bonding conditions were optimized by changing the bonding temperature and bonding pressure. The electrical properties were characterized by measuring the contact resistance of the ACF bonding area, yielding a measure that was used to optimize the applied pressure and temperature. The optimal conditions consisted of applying a pressure of 4 kg f/cm(2) and a temperature of 180 °C for 20 s. Although ACF base bonding is widely used in industry (e.g., liquid crystal display manufacturing), this study constitutes the first trial of a biomedical application. We performed a preliminary in vivo biocompatibility investigation of ACF bonded area. Using the optimized temperature and pressure conditions, we interconnected a 40-channel PI multielectrode device for measuring electroencephalography (EEG) signals from the skulls of mice. The electrical properties of electrode were characterized by measuring the impedance. Finally, EEG signals were measured from the mice skulls using the fabricated devices to investigate suitability for application to biomedical devices.