Utility of accelerated T2-weighted turbo spin-echo imaging with deep learning reconstruction in female pelvic MRI: a multi-reader study.

OBJECTIVES: To determine the clinical feasibility of T2-weighted turbo spin-echo (T2-TSE) imaging with deep learning reconstruction (DLR) in female pelvic MRI compared with conventional T2 TSE in terms of image quality and scan time. METHODS: Between May 2021 and September 2021, 52 women (mean age, 44 years ± 12) who underwent 3-T pelvic MRI with additional T2-TSE using a DLR algorithm were included in this single-center prospective study with patient's informed consents. Conventional, DLR, and DLR T2-TSE images with reduced scan times were independently assessed and compared by four radiologists. The overall image quality, differentiation of anatomic details, lesion conspicuity, and artifacts were evaluated using a 5-point scale. Inter-observer agreement of the qualitative scores was compared and reader protocol preferences were then evaluated. RESULTS: In the qualitative analysis of all readers, fast DLR T2-TSE showed significantly better overall image quality, differentiation of anatomic regions, lesion conspicuity, and lesser artifacts than conventional T2-TSE and DLR T2-TSE, despite approximately 50% reduction in scan time (all p < 0.05). The inter-reader agreement for the qualitative analysis was moderate to good. All readers preferred DLR over conventional T2-TSE regardless of scan time and preferred fast DLR T2-TSE (57.7-78.8%), except for one who preferred DLR over fast DLR T2-TSE (53.8% vs. 46.1%). CONCLUSION: In female pelvic MRI, image quality and accelerated image acquisition for T2-TSE can be significantly improved by using DLR compared to conventional T2-TSE. Fast DLR T2-TSE was non-inferior to DLR T2-TSE in terms of reader preference and image quality. CLINICAL RELEVANCE STATEMENT: DLR of T2-TSE in female pelvic MRI enables fast imaging along with maintaining optimal image quality compared with parallel imaging-based conventional T2-TSE. KEY POINTS: • Conventional T2 turbo spin-echo based on parallel imaging has limitations for accelerated image acquisition while maintaining good image quality. • Deep learning image reconstruction showed better image quality in both images obtained using the same or accelerated image acquisition parameters compared with conventional T2 turbo spin-echo in female pelvic MRI. • Deep learning image reconstruction enables accelerated image acquisition while maintaining good image quality in the T2-TSE of female pelvic MRI.

Comparison between Conventional Breath-hold and Respiratory-triggered Magnetic Resonance Cholangiopancreatography with and without Compressed Sensing: Cross-sectional Study.

AIM: The application of compressed sensing (CS) has enabled breath-hold 3D-MRCP with a shorter acquisition time in clinical practice. INTRODUCTION: To compare the image quality of breath-hold (BH) and respiratory-triggered (RT) 3D-MRCP with or without CS application in the same study population. METHODS: In this retrospective study, from February to July 2020, a total of 98 consecutive patients underwent four different acquisition types of 3D-MRCP.; 1) BH MRCP with the generalized autocalibrating partially parallel acquisition (GRAPPA) (BH-GRAPPA), 2) RT-GRAPPA-MRCP, 3) RT-CS-MRCP and 4) BH-CS-MRCP. Relative contrast of common bile duct, 5-scale visibility score of biliary pancreatic ducts, 3-scale artifact score and 5-scale overall image quality score were evaluated by two abdominal radiologists. RESULTS: Relative contrast value was significantly higher in BH-CS or RT-CS than in RT-GRAPPA (0.90 ± 0.057 and 0.89 ± 0.079, respectively, vs. 0.82 ± 0.071, p < 0.01) or BH-GRAPPA (vs. 0.77 ± 0.080, p < 0.01). The area affected by artifact was significantly lower in BH-CS among 4 MRCPs (p < 0.08). Overall image quality score in BH-CS was significantly higher than BH-GRAPPA (3.40 vs. 2.71, p < 0.01). There were no significant differences between RT-GRAPPA and BH-CS (vs. 3.13, p = 0.67) in overall image quality. CONCLUSION: In this study, our results revealed BH-CS had higher relative contrast and comparable or superior image quality among four MRCP sequences.

Analysis of Volumetric Perfusion Quantitative Parameters Using CS-VIBE Breast Dynamic Contrast Enhanced MR Imaging.

PURPOSE: To evaluate the diagnostic performance of three-dimensional volume of interest (3D-VOI) perfusion quantitative parameters using CS-VIBE DCE-MRI and investigate the relationship of the prognostic factors. MATERIALS AND METHODS: The volumetric perfusion quantitative parameters of Ktrans, Kep, Ve, Vp, of 124 pathologically proven breast masses in 93 patients were obtained using the two-compartment extended Tofts model. Also, the perfusion parameters of AUC, TTP, Emax, wash-in, and washout were automatically calculated using post-processing software. The relationship between the perfusion quantitative parameters and lesion size, pathology, and prognostic factors of malignancy was evaluated. RESULTS: Ktrans and Kep were significantly higher in the malignant than the benign lesions (p < 0.001), and the AUROC of Ktrans and Kep was 0.802 and 0.815, respectively. The area under the DCE curve, TTP, Emax, wash-in, and wash-out were significantly different between the benign and malignant lesions (p < 0.05). In multiple linear regression analysis, Ktrans and Kep were significantly different between benign and malignant tumors. Malignant tumors larger than 2cm were significantly different from those smaller than 2cm in Ktrans, Kep, Vp, area under the DCE curve, TTP, Emax, and wash-in values (p < 0.05). TTP was significantly lower in higher Ki-67 index (p < 0.05). CONCLUSION: Perfusion quantitative parameters may be applied as a feasible imaging biomarker to discriminate malignant from benign tumors. In malignant lesions, perfusion parameters were not associated with histopathological results but only in tumor size.

Feasibility of deep learning k-space-to-image reconstruction for diffusion weighted imaging in patients with breast cancers: Focus on image quality and reduced scan time.

PURPOSE: This study aimed to evaluate the feasibility of accelerated DLR (deep learning reconstruction) single-shot echo planar imaging (ss-EPI) for diffusion-weighted image (DWI) in patients with breast cancers in comparison to conventional ss-EPI. METHODS: Between August 2021 and February 2022, eighty-seven patients with pathologically proven breast cancer underwent DCE breast MRI including ss-EPI and DLR ss-EPI DWI sequences (TA, 3:36 min and 1:54 min, respectively) at 3 Tesla. In a randomized and blinded manner, two radiologists independently performed qualitative analyses for overall image quality using a 5-point scale of the following components: homogeneous fat suppression, image blurring, artifact, and lesion conspicuity. Quantitative analyses were performed by measurement of ADC values, SNR, CNR, and lesion contrast. RESULTS: DLR ss-EPI showed better image quality scores, CNR, and lesion contrast than ss-EPI (all P < 0.05) while reducing scan time by 47.2 %. DLR ss-EPI showed no significant difference in SNR and tumor ADC values compared to -ss-EPI (P = 0.307 and P = 0.123, respectively). CONCLUSIONS: DLR ss-EPI showed better results in the qualitative and quantitative analysis than conventional ss-EPI despite reducing scan time by 47.2%.

CS-VIBE accelerates cranial nerve MR imaging for the diagnosis of facial neuritis: comparison of the diagnostic performance of post-contrast MPRAGE and CS-VIBE.

OBJECTIVE: We aimed to compare the diagnostic performance of post-contrast 3D compressed sensing volume-interpolated breath-hold examination (CS-VIBE) and 3D T1 magnetization-prepared rapid-acquisition gradient-echo (MPRAGE) in detecting facial neuritis. MATERIALS AND METHODS: Between February 2019 and September 2019, 60 patients (30 facial palsy patients and 30 controls) who underwent contrast-enhanced cranial nerve MRI with both conventional MPRAGE and CS-VIBE (scan time: 6 min 8 s vs. 2 min 48 s) were included in this retrospective study. All images were independently reviewed by three radiologists for the presence of facial neuritis. In patients with facial palsy, signal-to-noise ratio (SNR) of the pons, enhancement degree and contrast-to-noise ratio (CNRnerve-CSF) of the facial nerve were measured. The overall image quality, artifacts, and facial nerve discrimination were analyzed. The sensitivity and specificity of both sequences were calculated with the clinical diagnosis as a reference. RESULTS: CS-VIBE had comparable performance in the detection of facial neuritis to that of MPRAGE (sensitivity and specificity, 97.8% and 99.4% vs. 100.0% and 99.4% in pooled analysis; 97.8% and 98.9% vs. 100.0% and 98.9% in patents with facial palsy, p value > 0.05 for all). CS-VIBE showed significantly lower SNR (p value < 0.001 for all), but significantly higher CNRnerve-CSF (p value < 0.05 for all) than MPRAGE. CS-VIBE also performed better in the overall image quality, artifacts, and facial nerve discrimination than MPRAGE (p value < 0.001 for all). CONCLUSION: CS-VIBE achieved comparable diagnostic performance for facial neuritis compared to the conventional MPRAGE, with the scan time being half of that of MPRAGE. KEY POINTS: • Post-contrast 3D CS-VIBE MRI is a reliable method for the diagnosis of facial neuritis. • CS-VIBE reduces the scan time of cranial nerve MRI by more than half compared to conventional T1-weighted image. • CS-VIBE had better performance in contrast-to-noise ratio and favorable image quality compared with conventional T1-weighted image.

Free-breathing contrast-enhanced multiphase MRI of the liver in patients with a high risk of breath-holding failure: comparison of compressed sensing-accelerated radial and Cartesian acquisition techniques.

BACKGROUND: Knowing the advantages and disadvantages of each magnetic resonance (MR) technique, would allow us to choose a sequence better suited in patients with a high risk of breath-holding failure. PURPOSE: To compare the image quality of free-breathing contrast-enhanced multiphase MR imaging (MRI) using incoherent Cartesian k-space sampling combined with a motion-resolved compressed sensing reconstruction (XD-VIBE) and Golden-Angle Radial Sparse Parallel MRI (GRASP). MATERIAL AND METHODS: A total of 67 patients were included. Overall image quality, motion artifacts, and liver edge sharpness on arterial and portal-venous phase were evaluated by two radiologists. We evaluated the signal intensity ratio between liver in the late arterial phase to aorta at peak enhancement and the detection rate of hypervascular lesions. RESULTS: Overall image quality, artifact, and liver edge sharpness scores of XD-VIBE and GRASP were not significantly different (P = 0.070-0.397). Four (reviewer 1, 12.1%) and seven patients (reviewer 2, 21.2%) received non-diagnostic quality in the XD-VIBE group whereas one patient (reviewer 2, 2.9%) received non-diagnostic quality in the GRASP group. The ratio between the aorta and liver signal for GRASP was significantly higher than that of XD-VIBE (0.32 ± 0.10 vs. 0.47 ± 0.13; P < 0.001). The hypervascular lesion detection rate of XD-VIBE (86.7%) was higher than that of GRASP (57.1%) in the arterial phase without a statistically significant difference (P = 0.081). CONCLUSION: Overall image quality of XD-VIBE and GRASP were not significantly different. More XD-VIBE examinations were rated non-diagnostic. On the other hand, the relative liver parenchymal enhancement to the aorta in the late arterial phase of GRASP was higher than that of XD-VIBE, which potentially leads to lower detectability of hypervascular lesions on arterial phase images.

Modified Reduced Field-of-View Diffusion-Weighted Magnetic Resonance Imaging of the Prostate: Comparison With Reduced Field-of-View Imaging and Single Shot Echo-Planar Imaging.

OBJECTIVE: The objective of this study was to compare the image quality and apparent diffusion coefficient (ADC) of diffusion-weighted imaging (DWI) with modified reduced field of view (FOV) based on 2-dimensional (2D)-selective radiofrequency excitations by tilting the excitation plane in prostate with reduced FOV using parallel-transmit-accelerated 2D-selective radiofrequency excitation and single-shot echo planar imaging (ssEPI). METHODS: Fifty patients who underwent multiparametric magnetic resonance imaging including 3 DWIs were included. Two observers independently performed qualitative image analyses using 5-point scale. Apparent diffusion coefficient measurements were performed for quantitative analysis. RESULTS: Modified reduced FOV provided the highest qualitative scores for all categories compared with reduced FOV and ssEPI (P < 0.000). Both reduced FOV DWIs showed higher ADC values compared with ssEPI (P < 0.001); however, the ADC ratios between the lesion and peripheral zone were not significantly different (all P > 0.05). CONCLUSIONS: The modified reduced FOV DWI showed better overall image quality, differentiability of anatomic regions, and lesion conspicuity with fewer artifacts compared with DWI with reduced FOV and ssEPI.

A preliminary study of the combination of ultrafast and abbreviated dynamic contrast: Enhanced breast magnetic resonance imaging.

We combined the abbreviated and ultrafast magnetic resonance imaging (MRI) technique with the standard MRI protocol and compared lesion characterization quantitatively and qualitatively to the standard MRI protocol.Fifty-six patients with breast cancer who underwent MRI from June 2017 to May 2018 and fulfilled our inclusion criteria were included. Three radiologists measured the lesion sizes, described the MRI findings using BI-RADS lexicon, and demarcated the regions of interest to extract the volumetric quantitative and semi-quantitative parameters. We used Pearson's correlation analysis comparing the quantitative and semi-quantitative parameters. To evaluate the inter-observer variability, we calculated the intra-correlation coefficient (ICC). We also analysed the correlation in BI-RADS lexicon.There were 45 (80.4%) luminal and 11 (19.6%) non-luminal breast cancers, and the most common tumour subtype was invasive carcinoma (n = 48, 85.7%), followed by ductal carcinoma in situ (n = 8, 14.3%). Regarding correlation between the quantitative and semi-quantitative parameters, K significantly correlated with the wash-in factor (r, 0.862; P < .001) and AUC value (r, 0.951; P < .001). The lesion size measured by standard and combined abbreviated-ultrafast phases and that from the surgical pathological specimens showed moderate agreement (ICC range, 0.516-0.578). The ICCs among the 3 readers were excellent for lesion size measurement, BI-RADS lexicon regarding lesion type, mass shape, margin, internal enhancement, non-mass enhancement distribution, and internal enhancement by the standard and combined abbreviated-ultrafast protocols.The use of the modified and combined abbreviated-ultrafast MRI protocol provides a reliable measurement of the quantitative parameters and may aid in the screening of breast cancer.