Keywords: Breast, Breast, diffusion-weighted imaging; apparent diffusion coefficient; MRI; breast lesions.

Motivation: A simple, objective, and noninvasive approach is required to improve the diagnostic accuracy of MRI-only suspicious lesions.

Goal(s): We aimed to assess whether using standard DWI sequences could increase the diagnostic performance of MRI for MRI-only breast lesions and reduce unnecessary MRI-guided biopsies.

Approach: In our current work, we intend to use the quantitative assessment of the heterogeneity of the ADC value to explore the diagnostic value of conventional DWI sequences for MRI-only lesions.

Results: Our results showed that quantitative ADC metrics based on large 2D-ROI measurements, particularly mean ADC values, exhibited superior performance over BI-RADS features in distinguishing MRI-only suspicious lesions.

Impact: DWI quantitative parameters may significantly improve diagnostic ability of BI-RADS-based features of breast MRI and provide additional value for the discrimination of MRI-only suspicious lesions.

Keywords: Breast, Gradients, Gradient Non linearity

Motivation: Improve accuracy of ADC measurement by correcting spatial nonuniformity of diffusion weighting caused by gradient nonlinearity (GNL) using novel vendor implemented on-scanner tools 

Goal(s): Evaluate GNL correction of breast tumor ADC in a treatment response study  

Approach: Implement on-scanner GNL correction, evaluate uncorrected and corrected tumor ADCs, evaluate GNL bias and ADC changes pre-treatment and post one cycle of neoadjuvant chemotherapy.

Results: Preliminary results from this study indicate adequate performance of the vendor implemented GNL correction of ADC in breast DWI assessment of response to neoadjuvant chemotherapy. 

Impact: This pilot study demonstrates vendor-implemented GNL-correction (GNC) of spatially dependent b-value bias can dramatically simplify the process of obtaining more accurate ADC measures, which can improve robustness of ADC as a biomarker for treatment response.

Keywords: Breast, Breast, Cancer, Image Registration, Treatment Response

Motivation: Tumor delineation is a challenging but critical step for ADC calculation in Diffusion-weighted (DW) MRI. Automated delineation methods are still underdeveloped for DW-MRI.

Goal(s): To compare the predictive performance of manual vs. automated ADC values at multiple timepoints during neoadjuvant treatment.

Approach: We used MRI data from the ACRIN 6698 trial for this analysis. Automated ADC values were computed using transformed ROIs from image registration between pre-contrast DCE and DWI (b=0). 

Results: Predictive performance improved with automated ADC values at 3-week timepoint and remained similar at 12-week and pre-surgery timepoints.

Impact: This work offers a practical approach for automated ADC calculation, allowing radiologists to expedite clinical decisions for breast cancer patients at early treatment timepoints; therefore, improving patient care.

Keywords: Breast, Breast, Magnetic resonance imaging; Nomogram; Diffusion-weighted imaging; Histogram analysis

Motivation: MRI-only lesions tend to be small in size and often have limited specific morphologic features on MRI, posing a significant diagnostic challenge for clinicians.

Goal(s): A simple, objective, and noninvasive approach is required to improve the diagnostic accuracy of MRI-only lesions.

Approach: We aimed to develop and validate a nomogram combining clinicoradiologic features and ADC-based histogram parameters for MRI-only suspicious lesions.

Results: Our results showed that ADC entropy in histogram parameters and kinetic pattern in clinicoradiologic parameters were identified as the most valuable predictors for differentiating MRI-only lesions, and a nomogram combining them exhibited better diagnostic performance than the two variables alone.

Impact: A nomogram combining ADC entropy and kinetic pattern, as a simple, objective, and noninvasive tool, displays satisfactory diagnostic performance for MRI-only suspicious lesions and may be utilised to avoid unnecessary biopsy.

Keywords: Breast, Screening, ADC, breast cancer, biopsy reduction

Motivation: Apparent Diffusion Coefficient (ADC) measures can help reduce false positives in breast MRI.

Goal(s): Explore different approaches for measuring lesion ADC that emphasize different aspects of tumor microenvironment and biology and their effect on reducing unnecessary biopsies.

Approach: Nine ADC measures were computed for each lesion using different b value combinations and segmentation techniques. Different approaches of selecting ADC threshold were explored to reduce unnecessary biopsies.

Results: Applying ADC cutoffs, the largest reduction of benign biopsies (~20%) was achieved using ADC_0-800 mapping and the 2D lesion segmentation technique, with the hotspot ROI measurement providing very similar performance.

Impact: This study demonstrates that a variety of ADC measurement techniques can help reduce unnecessary biopsies of breast MRI, suggesting that the easiest approach of segmenting the darkest pixels in the lesion might facilitate integration of DWI into the clinical workflow.

Keywords: Breast, Breast, MRI; MUSE-IVIM; IVIM; HER-2

Motivation: Few studies had explored different diffusion imaging techniques of magnetic resonance imaging for molecular prognostic factors of breast cancer, and human epidermal growth factor receptor-2(HER-2) was closely related to targeted therapy.

Goal(s): To compare the effect of high-resolution magnetic resonance intravoxel incoherent motion based on multiplexed sensitivity encoding (MUSE-IVIM) and conventional IVIM in predicting HER-2 status in breast cancer.

Approach: Different parameters of MUSE-IVIM and IVIM within and around the tumor were analyzed, including apparent diffusion coefficient (ADC), tissue diffusivity (Dt), pseudo diffusivity (Dp), perfusion fraction (f).

Results: IVIM-Dt-intratumoral predicted HER-2 with the highest value(AUC=0.775, P=0.003).

Impact: Although the signal to noise ratio (SNR) of MUSE-IVIM was higher than IVIM, they may be evenly matched in predicting HER-2 in breast cancer, which required more research and exploration.

Keywords: Breast, Breast, Tissue heterogeneity, tissue vascularity, perfusion, advanced DWI, non-Gaussian DWI

Motivation: This study is driven by the pressing need for the standardization of breast diffusion-weighted imaging (DWI) techniques.

Goal(s): The objective is to explore the influence of b-value selection on the parameters estimated by using an integrated DWI approach (DISMANTLE) that aims to simultaneously assess tissue cellularity, vascularity, and heterogeneity.

Approach: We conducted a systematic analysis by evaluating DISMANTLE parameters in healthy breast tissue using diverse b-value sampling strategies. 

Results: Our findings identified an ideal b-value distribution for accurate implementation of DISMANTLE in breast. This dataset included 12 b-values, reducing scan time by 34% compared to the comprehensive DWI protocol featuring broad b-value range.

Impact: This study emphasizes the role of b-value sampling in advanced breast DWI. Our systematic evaluation contributes to the potential success of advanced DWI techniques in breast imaging and the current discussion of the need for standardization in advanced DWI.

Keywords: Urogenital, Urogenital

Motivation: Conventional axial full-field-of-view (fFOV) DWI poorly demonstrates upper tract urothelial carcinoma (UTUC) due to its varying morphology and anatomical position. The additional coronal reduced field-of-view (rFOV) DWI may improve evaluation.

Goal(s): The objective of this study was to assess the diagnostic value and image quality of coronal rFOV DWI in the evaluation of UTUC.

Approach: This study compared the image quality, tumor contrast, ADC value, and staging accuracy between coronal rFOV DWI and axial fFOV DWI in UTUC.

Results: Coronal rFOV DWI provided better image quality and higher tumor contrast than fFOV DWI. It provided additional diagnostic value in the staging of UTUC.

Impact: This study validates the clinical application of reduced field-of-view DWI in the assessment of upper tract urothelial carcinoma. The use of this technique improves image quality and tumor conspicuity in the coronal plane, providing additional value for diagnosis and staging.

Keywords: Kidney, Kidney, normal right kidney; amide proton transfer; characteristic

Motivation: The changes in renal protein levels are closely related to physiological and pathological functions. Amide proton transfer weighted (APTw) imaging has the function of non-invasive and targeted detection of tissue-free proteins or peptides and is of great significance in the preliminary study of acute and chronic kidney diseases.

Goal(s): The study of APT imaging in normal kidneys still needs to be completed

Approach: The APT images study of 49 volunteers in this study.

Results: The APT values of the renal cortex and medulla were consistent, and the medulla was significantly higher than the cortex.

Impact: APT imaging is initially applied to the urinary system, such as chronic kidney disease, kidney cancer, etc. In this study, the application value of APTw imaging in renal dermal medulla was investigated

Keywords: Fetal, Kidney, Fetal kidney, diffusion-weighted imaging, kidney development

Motivation: Fetal magnetic resonance technology  provides morphological data of the fetal kidneys, as well as preliminary exploration of kidney function through DW-MRI. 

Goal(s): This project aims to investigate the correlation between gestational age and multi-quantitative MR parameter values of the fetal kidney. 

Approach: The kidney size,  thickness, T2 signal  and ADC quantitative parameters of normal fetuses from 24 to 40 weeks of gestation were collected, analyzing the correlation between each parameter value and gestational age. 

Results: In conclusion,there was a positive correlation between fetal kidney size, parenchymal thickness and gestational age, and a negative correlation between renal ADC, T2 signal values and gestational age. 

Impact: This project achieved a preliminary assessment of fetal kidney development and provide essential quantitative data references for different developmental stages of the fetal kidney.

Keywords: Prostate, Prostate, DWI distortion

Motivation: DWI is crucial for prostate cancer imaging, but its susceptibility to image distortion poses challenges to reading and leads to a substantial rate of nondiagnostic scans. 

Goal(s): This study aimed to develop and compare two algorithms for automatic distortion assessment for prostate DWI.

Approach: Two automatic distortion assessment methods were developed based on image segmentation, and deformable registration. Both were validated and compared using radiology grading as the reference. 

Results: Both distortion assessment methods quantified the levels of image distortion in prostate DWI consistent with visual assessments and correlated well with expert ratings.  The deformable registration-based approach appeared to outperform its counterpart. 

Impact: The developed methods for automatic assessment of image distortion may assist in acquiring high-quality prostate DWI and reducing patient recalls.  

Keywords: Prostate, Prostate, Diffusion

Motivation: Diffusion-weighted imaging is critical to the diagnosis of prostate cancer but can be limited by noise. A commercially available 200mT/m gradient system may allow revisiting of higher b-value DWI.

Goal(s): To optimise a feasible high b-value prostate MR protocol for clinical use.

Approach: Phantom, simulation and in vivo iterative optimisation were evaluated against technical metrics and novel discrete choice experimental design for radiologist preference.

Results: Radiologist DWI preference is weighted by signal-to-noise. Emerging high gradient performance and deep learning reconstruction can reduced decline in SNR potentiating a signal-optimised high b-value protocol for clinical prostate cancer imaging within feasible scan times.

Impact: Signal-optimised high b-value DWI for prostate cancer using a 200mT/m gradient 3T MRI system may be clinically feasible and supports a scalable trial of its diagnostic impact.

Keywords: Prostate, Cancer

Motivation: Diagnosing clinically significant prostate cancer(PCa) while avoiding overdiagnosis is crucial. Quantitative imaging techniques allow for more objective assessment of prostate lesions. Magnetic resonance fingerprinting(MRF) combined with apparent diffusion coefficient(ADC) might allow quantitative characterization of prostate lesions. Further validation studies with histopathological correlation are required.

Goal(s): To evaluate the utility of MRF and ADC for quantitative characterization of prostate lesions and correlate our results with pathology.

Approach: This study included 106 biopsy-naive patients with elevated PSA levels that underwent an mpMRI exam with additional acquisition of MRF.

Results: ADC and MRF based relaxometry allow quantitative characterization of prostate lesions that correlate with histopathology.

Impact: There is growing interest in the clinical application of quantitative imaging techniques for more objective assessment of prostate lesions. MRF is a fast and efficient method that promises to quantitatively characterize PCa in the future.

Keywords: Urogenital, Bladder, cancer

Motivation: The limitations of current diffusion-weighted imaging (DWI) techniques in predicting muscle invasion in bladder cancer necessitate a comprehensive comparison of different DWI sequences to improve diagnostic accuracy.

Goal(s): Evaluate the image quality of four diffusion sequences(ssDWI/FOCUS/MUSE/FOCUS-MUSE)  and assess their effectiveness in predicting muscle invasion in bladder cancer.

Approach: 44 primary bladder cancer patients underwent imaging using clinical and four diffusion weighted imaging (DWI) sequences

Results: Among the four diffusion sequences, field-of-view optimized and constrained undistorted single-shot (FOCUS) combined with multiplexed sensitivityencoding (MUSE) has the best image quality, and the highest accuracy in predicting muscle invasion of bladder cancer.

Impact: FOCUS-MUSE diffusion weighted imaging can accurately predict muscle invasion of bladder cancer.

Keywords: Urogenital, Bladder, Intravoxel Incoherent Motion, Amide Proton Transfer-Weighted Imaging, Bladder Cancer Grading

Motivation: Preoperative grading of bladder cancer (BC) impacts the choice of operative modality and prognosis of patients. 

Goal(s): We aimed to perform an accurate and non-invasive preoperative grading method for BC by MRI sequences.

Approach: IVIM as well as APTw imaging were included in this study.

Results: The IVIM-related parameter (D, true-diffusion-coefficient) and APTw values were significantly different in low- and high-grade BC. Robust diagnostic efficacies were separately confirmed with high AUCs for IVIM and APTw in BC grading, and the diagnostic efficacy of the combined IVIM and APTw model was significantly higher compared to the individual parameters on their own.
 

Impact: Our findings suggest a complementary effect between the IVIM and APTw imaging parameters The combined model shows promise as a noninvasive biomarker for predicting BC histologic grading, aiding in the development of clinical therapeutic strategies, and assessing prognosis.

Keywords: Placenta, Placenta, Perfusion, Diffusion, COVID-19, Microstructural damage

Motivation: Currently, no study has investigated the role of diffusion-MRI to assess the placenta of women getting SARS-CoV-2 infection. 

Goal(s): To study the placental tissues abnormalities due to the infection.

Approach: Pregnant women COVID-19 group (n=14) and pre-pandemic healthy women (n=19) were investigated using IVIM protocol at 1.5T.

Results:  D was significantly higher in the COVID-19 compared to that of the age-matched healthy group. No-significant difference between f values was found in the two groups suggesting no-specific microstructural damage with no-perfusion alteration. A significant negative correlation was found between D and GA only in the COVID-19 reflecting a possible senescence process due to COVID-19.

Impact: Diffusion MRI underline higher D value in SARS-Cov-2 compared to healthy placentas, which can be explained as a microstructural deterioration of the placental tissue. Further investigations will allow us better to understand the effects of SARS-Cov-2 infection on human tissues.