Megumi Matsuda

This study aimed to assess diagnostic values of kinetic parameters in ultrafast dynamic contrast magnetic resonance imaging. The diagnostic performance of ultrafast kinetic parameters (time to enhancement [TTE], maximum slope [MS], time to peak, peak enhancement [PE], and wash-in slope [WIS]), and their correlations with the immunohistopathological findings of breast cancer were evaluated for 101 histologically proven breast lesions. We found that the areas under the curves of five ultrafast kinetic parameters in masses (0.69–0.81) and for MS, PE, and WIS in non-mass enhancement (NME) (0.91–0.94) were comparable to those of Breast Imaging Reporting and Data System (BI-RADS) categorizations (mass: 0.85, NME: 0.83) without statistically significant differences. Values of ultrafast kinetic parameters differed significantly according to invasiveness (invasive vs. non-invasive: TTE, p = 0.029; MS, p = 0.040; PE, p = 0.032; and WIS, p = 0.009), immunohistopathological findings (high vs. low Ki-67: TTE, p = 0.020; MS, p = 0.004; PE, p = 0.003; and WIS, p < 0.001), hormone receptor (negative vs. positive: MS, p = 0.033; and WIS, p = 0.042), and triple-negative status (triple-negative vs. non-triple-negative: MS, p = 0.028; and WIS, p = 0.011) in breast cancer. In conclusion, ultrafast kinetic parameters demonstrate diagnostic performance comparable to that of BI-RADS categories for both mass and NME and may be associated with the immunohistopathological findings of breast cancer.

Purpose: To evaluate the effects of four-dimensional noise reduction filtering using a similarity algorithm (4D-SF) on the image quality and tumor visibility of low-dose dynamic computed tomography (CT) in evaluating breast cancer. Materials and methods: Thirty-four patients with 38 lesions who underwent low-dose dynamic breast CT and were pathologically diagnosed with breast cancer were enrolled. Dynamic CT images were reconstructed using iterative reconstruction alone or in combination with 4D-SF. We selected the peak enhancement phase image of breast cancer for each patient for quantitative and qualitative evaluations of image quality and measurement of the maximum diameter of breast cancer. The signal-to-noise and contrast-to-noise ratios were calculated for quantitative evaluation. The maximum diameters of the breast cancer were measured from the images obtained with and without 4D-SF (4D-SF ±) (size-4D-SF + and size-4D-SF-) and for the pathological specimen (size-PS) and compared. Results: The median and interquartile ranges of the signal-to-noise ratio [4D-SF-: 3.03 (2.54–4.17) vs 4D-SF + : 5.52 (4.75–6.66)] and contrast-to-noise ratio [4D-SF-: 2.88 (2.00–3.60) vs 4D-SF + : 7.84 (4.65–10.35)] were significantly higher for 4D-SF + than for 4D-SF- (p < 0.001). The overall image quality (Observer 1, p < 0.001; Observer 2, p < 0.001) and tumor margin sharpness scores (Observer 1, p = 0.003; Observer 2, p < 0.001) were significantly higher for 4D-SF + than for 4D-SF-. The tumor contrast scores for 4D-SF + and 4D-SF- were not significantly different (Observers 1, 2; p = 0.083). Size-4D-SF- was significantly smaller than size-PS (p < 0.001); size-4D-SF + was also smaller than size-PS, but the difference was not significant (p = 0.088). The Spearman’s rank correlation coefficient was 0.65 for size-PS and size-4D-SF- and 0.77 for size-PS and size-4D-SF + . Conclusion: The 4D-SF can improve the image quality and tumor visibility of low-dose dynamic CT in evaluating breast cancer extent due to noise reduction.

Breast MRI has become essential for diagnosing and managing breast diseases. MRI interpretation has traditionally relied on subjective assessment according to Breast Imaging-Reporting and Data System, but recent advances emphasize the value of quantitative MRI data as objective imaging biomarkers. Techniques such as dynamic contrast-enhanced MRI (DCE-MRI), including ultrafast DCE-MRI and diffusion-weighted imaging are the most established for quantitative analysis, yet their routine application is limited by a lack of standardization in imaging protocols. Recent efforts focus on improving reproducibility, with studies showing that significant changes in the apparent diffusion coefficient can reliably indicate biological alterations in breast lesions. Emerging quantitative MRI approaches including synthetic MRI and fat imaging show promise in lesion characterization and treatment response assessment but require further validation and harmonization before widespread clinical use. For methodological aspect, radiomics has demonstrated strong diagnostic and predictive capabilities in breast MRI research. Quantitative approach for background parenchymal enhancement indicated its association with future breast cancer incidence or recurrence. Continued efforts to standardize and validate quantitative MRI parameters are crucial to fully integrating these tools into routine breast imaging practice.

Objective: This study aimed to compare the image quality in the hepatobiliary phase images of gadoxetic acid–enhanced liver magnetic resonance imaging using parallel imaging (PI) and compressed sensing (CS) reconstruction, using variable CS factors with the standard method using the PI technique. Methods: In this study, 64 patients who underwent gadoxetic acid–enhanced liver magnetic resonance imaging at 3.0 T were enrolled. Hepatobiliary phase images were acquired 6 times using liver acquisition with volume acceleration (LAVA) and CS reconstruction with 5 CS factors 1.4, 1.6, 1.8, 2.0, and 2.5 (LAVA-CS 1.4, 1.6, 1.8, 2.0, and 2.5) and standard LAVA (LAVA-noCS). For objective analysis, the signal intensity ratios (SIRs) of the liver-to-spleen (SIR_liver/spleen), liver-to-portal vein (SIR_{liver/portal vein}), and liver-to-fat (SIR_liver/fat) were estimated. For subjective analysis, 2 radiologists independently evaluated the quality of all the images. Results: The objective analysis demonstrated no significant difference in all evaluation parameters of all the images. Subjective analysis revealed that the scores of all evaluation items were higher for LAVA-noCS images than for LAVA-CS images, and only LAVA-CS 1.4 did not significantly differ from LAVA-noCS in all evaluation items (P = 1.00 in 2 readers). Conclusions: A CS factor of 1.4 in the hepatobiliary phase image with combined PI and CS can reduce the scan time without degrading the image quality compared with the standard method.

Background: The addition of synthetic MRI might improve the diagnostic performance of dynamic contrast‐enhanced MRI (DCE‐MRI) in patients with breast cancer.Purpose: To evaluate the diagnostic value of a combination of DCE‐MRI and quantitative evaluation using synthetic MRI for differentiation between benign and malignant breast masses.Study Type: Retrospective, observational.Population: In all, 121 patients with 131 breast masses who underwent DCE‐MRI with additional synthetic MRI were enrolled.Field Strength/Sequence: 3.0 Tesla, T₁‐weighted DCE‐MRI and synthetic MRI acquired by a multiple‐dynamic, multiple‐echo sequence.Assessment: All lesions were differentiated as benign or malignant using the following three diagnostic methods: DCE‐MRI type based on the Breast Imaging–Reporting and Data System; synthetic MRI type using quantitative evaluation values calculated by synthetic MRI; and a combination of the DCE‐MRI + Synthetic MRI types. The diagnostic performance of the three methods were compared.Statistical Tests: Univariate (Mann–Whitney U‐test) and multivariate (binomial logistic regression) analyses were performed, followed by receiver‐operating characteristic curve (AUC) analysis.Results: Univariate and multivariate analyses showed that the mean T₁ relaxation time in a breast mass obtained by synthetic MRI prior to injection of contrast agent (pre‐T₁) was the only significant quantitative value acquired by synthetic MRI that could independently differentiate between malignant and benign breast masses. The AUC for all enrolled breast masses assessed by DCE‐MRI + Synthetic MRI type (0.83) was significantly greater than that for the DCE‐MRI type (0.70, P < 0.05) or synthetic MRI type (0.73, P < 0.05). The AUC for category 4 masses assessed by the DCE‐MRI + Synthetic MRI type was significantly greater than that for those assessed by the DCE‐MRI type (0.74 vs. 0.50, P < 0.05).Data Conclusion: A combination of synthetic MRI and DCE‐MRI improves the accuracy of diagnosis of benign and malignant breast masses, especially category 4 masses.Level of Evidence 4Technical Efficacy Stage 2J. MAGN. RESON. IMAGING 2021;53:381–391.

Purpose: This study aimed to evaluate the utility of virtual monoenergetic images for detecting washout of small (≤2 cm) hepatocellular carcinoma (HCC) in the equilibrium phase. Methods: We performed 120-kVp–equivalent linear-blended (M120) and monoenergetic reconstructions from 40 to 90 keV by standard (40, 50, 60, 70, 80, 90) and novel noise-reduced (nMERA: 40+, 50+, 60+, 70+, 80+, 90+) monoenergetic reconstruction algorithms. Image quality and tumor visibility of delayed washout of HCCs in the equilibrium phase were compared between standard monoenergetic reconstruction algorithm and nMERA by objective and subjective analyses. Results: Contrast-to-noise ratio of the tumor at 40+ was the highest, whereas the score of tumor visibility peaked at 50+. The score of overall image quality at 40+ was significantly lower than those on all other image series, and the image quality among other image series were not significantly different. Conclusions: Virtual monoenergetic image reconstructed with nMERA 50+ was most appropriate to detect washout of small HCCs.

The purpose of this study was to elucidate the incidence and risk factors for the progression of hyperintense nodules, observed in the hepatobiliary phase of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-enhanced MRI), to hypervascular hepatocellular carcinoma (HCC). Hypovascular nodules (n = 157) showing hyperintensity in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI were examined in 41 patients. All patients underwent computed tomography (CT) during hepatic arteriography and CT during arterial portography within one month of Gd-EOB-DTPA-enhanced MRI. The incidence of progression to hypervascular or classical HCC was calculated using the Kaplan–Meier method. Tumor size was determined by univariate and multivariate analysis to be an important risk factor of hypervascularization (p = 0.041, odds ratio 1.135). The cumulative incidences of hypervascularization in hypovascular nodules showing hyperintensity on the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI were 2.4, 4.5, and 6.2 % at 12, 24, and 36 months, respectively. The incidence of hypervascularization was significantly increased in nodules >10 mm in diameter (p = 0.00035). In patients with chronic liver disease, hypovascular nodules presenting as hyperintense in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI and >10 mm in diameter have malignant potential for progression to hypervascular HCC and require careful management.