Background
Dynamic contrast‐enhanced (DCE) MRI is useful for diagnosis and assessment of treatment response in breast cancer. Fast DCE MRI offers a higher sampling rate of contrast enhancement curves ...in comparison to conventional DCE MRI, potentially characterizing tumor perfusion kinetics more accurately for measurement of functional tumor volume (FTV) as a predictor of treatment response.
Purpose
To investigate FTV by fast DCE MRI as a predictor of neoadjuvant systemic therapy (NAST) response in triple‐negative breast cancer (TNBC).
Study Type
Prospective.
Population/Subjects
Sixty patients with biopsy‐confirmed TNBC between December 2016 and September 2020.
Field Strength/Sequence
A 3.0 T/3D fast spoiled gradient echo‐based DCE MRI
Assessment
Patients underwent MRI at baseline and after four cycles (C4) of NAST, followed by definitive surgery. DCE subtraction images were analyzed in consensus by two breast radiologists with 5 (A.H.A.) and 2 (H.S.M.) years of experience. Tumor volumes (TV) were measured on early and late subtractions. Tumors were segmented on 1 and 2.5‐minute early phases subtractions and FTV was determined using optimized signal enhancement thresholds. Interpolated enhancement curves from segmented voxels were used to determine optimal early phase timing.
Statistical Tests
Tumor volumes were compared between patients who had a pathologic complete response (pCR) and those who did not using the area under the receiver operating curve (AUC) and Mann–Whitney U test.
Results
About 26 of 60 patients (43%) had pCR. FTV at 1 minute after injection at C4 provided the best discrimination between pCR and non‐pCR, with AUC (95% confidence interval CI) = 0.85 (0.74,0.95) (P < 0.05). The 1‐minute timing was optimal for FTV measurements at C4 and for the change between C4 and baseline. TV from the early phase at C4 also yielded a good AUC (95%CI) of 0.82 (0.71,0.93) (P < 0.05).
Data Conclusion
FTV and TV measured at 1 minute after injection can predict response to NAST in TNBC.
Level of Evidence
1
Technical Efficacy
4
A flexible fast spin echo triple‐echo Dixon technique Son, Jong Bum; Hwang, Ken‐Pin; Madewell, John E. ...
Magnetic resonance in medicine,
March 2017, 2017-03-00, 20170301, Letnik:
77, Številka:
3
Journal Article
Purpose
To determine if tumor necrosis by pretreatment breast MRI and its quantitative imaging characteristics are associated with response to NAST in TNBC.
Methods
This retrospective study included ...85 TNBC patients (mean age 51.8 ± 13 years) with MRI before NAST and definitive surgery during 2010–2018. Each MRI included T2-weighted, diffusion-weighted (DWI), and dynamic contrast-enhanced (DCE) imaging. For each index carcinoma, total tumor volume including necrosis (TTV), excluding necrosis (TV), and the necrosis-only volume (NV) were segmented on early-phase DCE subtractions and DWI images. NV and %NV were calculated. Percent enhancement on early and late phases of DCE and apparent diffusion coefficient were extracted from TTV, TV, and NV. Association between necrosis with pathological complete response (pCR) was assessed using odds ratio (OR). Multivariable analysis was used to evaluate the prognostic value of necrosis with T stage and nodal status at staging. Mann–Whitney
U
tests and area under the curve (AUC) were used to assess performance of imaging metrics for discriminating pCR vs non-pCR.
Results
Of 39 patients (46%) with necrosis, 17 had pCR and 22 did not. Necrosis was not associated with pCR (OR, 0.995; 95% confidence interval CI 0.4–2.3) and was not an independent prognostic factor when combined with T stage and nodal status at staging (
P
= 0.46). None of the imaging metrics differed significantly between pCR and non-pCR in patients with necrosis (AUC < 0.6 and
P
> 0.40).
Conclusion
No significant association was found between necrosis by pretreatment MRI or the quantitative imaging characteristics of tumor necrosis and response to NAST in TNBC.
To evaluate the clinical feasibility of a new T2 weighted sequence to calculate T2 relaxation times (T2RT) of liver lesions using two-dimensional radial turbo spin echo (2DRTSE) and to evaluate this ...sequence by performing image quality and relaxation time comparison of multiple liver lesions.
This prospective analysis of 2DRTSE sequences (using 22 echoes) was performed in 19 patients with 36 liver lesions. Two radiologists independently obtained T2RTs for liver lesions and scored image quality and image artifacts. Lesions were classified as cyst, hemangioma, solid, or necrotic. T2RT values were compared. Inter-reader agreement was evaluated.
The 2DRTSE images were considered good quality with few artifacts by both radiologists. Nineteen patients were included in the study, with a total of 36 liver lesions. Two of the liver lesions were classified as cysts, 7 as hemangiomas, 4 as necrotic lesions, and 23 as solid lesions. The concordance correlation coefficient was 0.996 for the calculated T2RT of each liver lesion between the two readers, indicating good agreement. There was statically significant difference of the calculated T2RT for each lesion type.
The 2DRTSE sequence can be performed and provides good T2W image quality and a quantitative T2RT map of the entire abdomen. The liver lesions can be distinguished based on the calculated T2RT using this technique. 2DRTSE could potentially supplant the current T2-weighted imaging sequence with the benefit of quantitative T2RTs.
•New 2DRTSE sequence provides high quality MR images of the liver.•T2W maps using 2DRTSE sequence can generate T2 relaxation time for liver lesions.•The T2RT, using 2DRTSE, are statistically significant between liver lesion types.•The T2RT, using 2DRTSE, compared favorably with prior results.
Demand for energy has increasing rapidly in the last decade. In 2021 an increase in 5% was observed. Half of this demand was covered by fossil fuels, increasing CO2 emissions to record levels. With ...the need for new reliable steady supply sources to be used in places where maintenance is difficult, Radioisotope Thermoelectric Generators (RTG) have been given renewed attention in the past 10 years. RTGs uses radioactive decay to generate electricity. This work presents in a simple manner, the basics of RTG operation, the requirements for construction, and is followed by an example developed at KAERI. Basic Radiation Physics Concepts, RTG configuration requirements, Thermoelectric effect and materials, and calculations for electric power were presented.
This paper presents the drop performance test of the control rod assembly which is one of the main components strongly related to the safety of the prototype generation IV sodium-cooled fast reactor. ...To investigate the drop performance, a real-sized control rod assembly that was recently modified based on the drop analysis results was newly fabricated, and several free drop tests under different flow rate conditions were carried out. Then the results were compared with those obtained from the previous tests conducted on the conceptually designed control rod assembly to demonstrate the improvement in performance. Moreover, the drop performance tests under several types and magnitudes of seismic loadings were also conducted to investigate the effect of the seismic loading on the drop performance of the modified control rod assembly. The results showed that the effects of the type and magnitude of the seismic loading on the drop performance of the modified control rod assembly were not significant. Also, the drop time requirement was successfully satisfied, even under the seismic loading conditions.
The microstructure of a cobalt-base alloy (Co-Cr-Mo) obtained by an investment casting process was studied. This alloy complies with the ASTM F75 standard and is widely used in the manufacturing of ...orthopedic implants owing to its high strength, good corrosion resistance, and excellent biocompatibility. This work focuses on the resulting microstructures arising from normal industrial environmental conditions. The characterization of the samples was carried out using optical microscopy, field emission scanning electron microscopy and energy-dispersive spectroscopy. In this study, the as-cast microstructure is an γ-Co (face-centered cubic) dendritic matrix with the presence of a secondary phase, such as M
23
C
6
carbides precipitated at grain boundaries and interdendritic zones. These precipitates are the main strengthening mechanism in this type of alloy. Other minority phases, such as the
σ
phase, were also detected, and their presence could be linked to the manufacturing process and environment.
18
F-FDG PET/CT can provide quantitative characterization with prognostic value for mantle cell lymphoma (MCL). However, detection of MCL is performed manually, which is labor intensive and not a ...part of the routine clinical practice. This study investigates a deep learning convolutional neural network (DLCNN) for computer-aided detection of MCL on
18
F-FDG PET/CT. We retrospectively analyzed 142 baseline
18
F-FDG PET/CT scans of biopsy-confirmed MCL acquired between May 2007 and October 2018. Of the 142 scans, 110 were from our institution and 32 were from outside institutions. An Xception-based U-Net was constructed to classify each pixel of the PET/CT images as MCL or not. The network was first trained and tested on the within-institution scans by applying five-fold cross-validation. Sensitivity and false positives (FPs) per patient were calculated for network evaluation. The network was then tested on the outside-institution scans, which were excluded from network training. For the 110 within-institution patients (85 male; median age, 58 range: 39-84 years), the network achieved an overall median sensitivity of 88% (interquartile range IQR: 25%) with 15 (IQR: 12) FPs/patient. Sensitivity was dependent on lesion size and SUV
max
but not on lesion location. For the 32 outside-institution patients (24 male; median age, 59 range: 40-67 years), the network achieved a median sensitivity of 84% (IQR: 24%) with 14 (IQR: 10) FPs/patient. No significant performance difference was found between the within and outside institution scans. Therefore, DLCNN can potentially help with MCL detection on
18
F-FDG PET/CT with high sensitivity and limited FPs.
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