Thin-slice 2D MR Imaging of the Shoulder Joint Using Denoising Deep Learning Reconstruction Provides Higher Image Quality Than 3D MR Imaging

PURPOSE: This study was conducted to evaluate whether thin-slice 2D fat-saturated proton density-weighted images of the shoulder joint in three imaging planes combined with parallel imaging, partial Fourier technique, and denoising approach with deep learning-based reconstruction (dDLR) are more useful than 3D fat-saturated proton density multi-planar voxel images. METHODS: Eighteen patients who underwent MRI of the shoulder joint at 3T were enrolled. The denoising effect of dDLR in 2D was evaluated using coefficient of variation (CV). Qualitative evaluation of anatomical structures, noise, and artifacts in 2D after dDLR and 3D was performed by two radiologists using a five-point Likert scale. All were analyzed statistically. Gwet's agreement coefficients were also calculated. RESULTS: The CV of 2D after dDLR was significantly lower than that before dDLR (P < 0.05). Both radiologists rated 2D higher than 3D for all anatomical structures and noise (P < 0.05), except for artifacts. Both Gwet's agreement coefficients of anatomical structures, noise, and artifacts in 2D and 3D produced nearly perfect agreement between the two radiologists. The evaluation of 2D tended to be more reproducible than 3D. CONCLUSION: 2D with parallel imaging, partial Fourier technique, and dDLR was proved to be superior to 3D for depicting shoulder joint structures with lower noise.

Thin-slice reverse encoding distortion correction DWI facilitates visualization of non-functioning pituitary neuroendocrine tumor (PitNET)/pituitary adenoma and surrounding normal structures.

BACKGROUND: To evaluate the clinical usefulness of thin-slice echo-planar imaging (EPI)-based diffusion-weighted imaging (DWI) with an on-console distortion correction technique, termed reverse encoding distortion correction DWI (RDC-DWI), in patients with non-functioning pituitary neuroendocrine tumor (PitNET)/pituitary adenoma. METHODS: Patients with non-functioning PitNET/pituitary adenoma who underwent 3-T RDC-DWI between December 2021 and September 2022 were retrospectively enrolled. Image quality was compared among RDC-DWI, DWI with correction for distortion induced by B0 inhomogeneity alone (B0-corrected-DWI), and original EPI-based DWI with anterior-posterior phase-encoding direction (AP-DWI). Susceptibility artifact, anatomical visualization of cranial nerves, overall tumor visualization, and visualization of cavernous sinus invasion were assessed qualitatively. Quantitative assessment of geometric distortion was performed by evaluation of anterior and posterior displacement between each DWI and the corresponding three-dimensional T2-weighted imaging. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and apparent diffusion coefficient values were measured. RESULTS: Sixty-four patients (age 70.8 ± 9.9 years [mean ± standard deviation]; 33 females) with non-functioning PitNET/pituitary adenoma were evaluated. In terms of susceptibility artifacts in the frontal and temporal lobes, visualization of left trigeminal nerve, overall tumor visualization, and anterior displacement, RDC-DWI performed the best and B0-corrected-DWI performed better than AP-DWI. The right oculomotor and right trigeminal nerves were better visualized by RDC-DWI than by B0-corrected-DWI and AP-DWI. Visualization of cavernous sinus invasion and posterior displacement were better by RDC-DWI and B0-corrected-DWI than by AP-DWI. SNR and CNR were the highest for RDC-DWI. CONCLUSIONS: RDC-DWI achieved excellent image quality regarding susceptibility artifact, geometric distortion, and tumor visualization in patients with non-functioning PitNET/pituitary adenoma. RELEVANCE STATEMENT: RDC-DWI facilitates excellent visualization of the pituitary region and surrounding normal structures, and its on-console distortion correction technique is convenient. RDC-DWI can clearly depict cavernous sinus invasion of PitNET/pituitary adenoma even without contrast medium. KEY POINTS: • RDC-DWI is an EPI-based DWI technique with a novel on-console distortion correction technique. • RDC-DWI corrects distortion due to B0 field inhomogeneity and eddy current. • We evaluated the usefulness of thin-slice RDC-DWI in non-functioning PitNET/pituitary adenoma. • RDC-DWI exhibited excellent visualization in the pituitary region and surrounding structures. • In addition, the on-console distortion correction of RDC-DWI is clinically convenient.

Evaluating Reproducibility of the ADC and Distortion in Diffusion-weighted Imaging (DWI) with Reverse Encoding Distortion Correction (RDC).

PURPOSE: To compare image distortion and reproducibility of quantitative values between reverse encoding distortion correction (RDC) diffusion-weighted imaging (DWI) and conventional DWI techniques in a phantom study and in healthy volunteers. METHODS: This prospective study was conducted with the approval of our institutional review board. Written informed consent was obtained from each participant. RDC-DWIs were created from images obtained at 3T in three orthogonal directions in a phantom and in 10 participants (mean age, 70.9 years; age range, 63-83 years). Images without distortion correction (noDC-DWI) and those corrected with B0 (B0c-DWI) were also created. To evaluate distortion, coefficients of variation were calculated for each voxel and ROIs were placed at four levels of the brain. To evaluate the reproducibility of apparent diffusion coefficient (ADC) measurements, intra- and inter-scan variability (%CVADC) were calculated from repeated scans of the phantom. Analysis was performed using Wilcoxon signed-rank test with Bonferroni correction, and P < 0.05 was considered statistically significant. RESULTS: In the phantom, distortion was less in RDC-DWI than in B0c-DWI (P < 0.006), and was less in B0c-DWI than in noDC-DWI (P < 0.006). Intra-scan %CVADC was within 1.30%, and inter-scan %CVADC was within 2.99%. In the volunteers, distortion was less in RDC-DWI than in B0c-DWI in three of four locations (P < 0.006), and was less in B0c-DWI than in noDC-DWI (P < 0.006). At the middle cerebellar peduncle, distortion was less in RDC-DWI than in noDC-DWI (P < 0.006), and was less in noDC-DWI than in B0c-DWI (P < 0.0177). CONCLUSION: In both the phantom and in volunteers, distortion was the least in RDC-DWI than in B0c-DWI and noDC-DWI.

Suppression of lymphangiogenesis by soluble vascular endothelial growth factor receptor-2 in a mouse lung cancer model.

The vascular endothelial growth factor (VEGF) family has a key role in the formation of blood vessels and lymphatics. Among the members of this family, VEGF-C is one of the most important factors involved in lymphangiogenesis via binding with two receptors (vascular endothelial growth factor receptor-2 and -3: VEGFR-2 and VEGFR-3). Soluble VEGFR-2 (sVEGFR-2) has a role in maintaining the alymphatic state of the cornea associated with binding to VEGF-C, and selectively inhibits lymphangiogenesis but not angiogenesis. In this study, we introduced sVEGFR-2 into lung cancer cells and evaluated the influence on tumor progression and on genes regulating lymphatic formation and metastasis in vivo. A retroviral vector was used to introduce the sVEGFR-2 gene into Lewis lung carcinoma cells (LLC), which were designated as LLC-sVEGFR-2 cells. Proteins secreted into the culture supernatant by these cells were detected by western blotting using specific antibodies. To examine lymphangiogenesis by primary lung cancer in vivo, LLC-sVEGFR-2 cells were subcutaneously injected into C57BL/6 mice. At 14days after injection, immunohistochemistry was performed using an antibody directed against lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), a marker of lymphatics. Expression of mRNA for VEGFR-2, VEGFR-3 and matrix metalloproteinases (MMPs) was also determined by real-time PCR. Furthermore, LLC-sVEGFR-2 cells were directly inoculated into the left lung in C57BL/6 mice and the number of micro-metastases in pulmonary lymph nodes was determined. Introduction of sVEGFR-2 into LLC cells resulted in secretion of sVEGFR-2 protein into the culture supernatant. There were fewer LYVE-1 positive lymphatics after inoculation of LLC-sVEGFR-2 into mice compared with the control group. In addition, VEGFR-2, VEGFR-3, and MMPs gene expression was suppressed in the primary tumors of the LLC-sVEGFR-2 group compared with the control group. Furthermore, there were fewer micro-metastases in the pulmonary lymph nodes of the LLC-sVEGFR-2 group compared with the control group after cells were directly inoculated into the lung. These findings indicate that introduction of sVEGFR-2 suppressed lymphangiogenesis in primary lung cancer and also suppressed lymphogenic metastasis by inhibiting VEGF-C, followed by down-regulation of VEGFR-2, VEGFR-3 and MMPs. Accordingly, sVEGFR-2 might be a promising target for treatment of cancer by regulating lymphangiogenesis and lymphogenic metastasis.