Jo Ishii

Purpose Diagnosing optic neuritis can be challenging, particularly in atypical cases where conventional MRI may be inconclusive. This study evaluates whether adding CE FS 3D FLAIR to standard orbital MRI improves diagnostic performance. Methods This retrospective single-center diagnostic accuracy study included 48 patients (mean age, 60 years ± 18; 30 women) clinically suspected of acute optic neuritis who underwent orbital MRI between September 2016 and July 2024. All underwent FS 2D T2WI, CE FS 3D T1WI, and CE FS 3D FLAIR. Definite optic neuritis was defined by combined clinical and paraclinical findings. Segment-, nerve-, and patient-based analyses were performed using confidence scores (≥ 4.0 = abnormal). Diagnostic performance of the standard protocol (FS 2D T2WI + CE FS 3D T1WI) and advanced protocol (FS 2D T2WI + CE FS 3D T1WI + CE FS 3D FLAIR) was compared. For nerve-level analyses, including ROC analysis, patient-level cluster bootstrap resampling was applied to account for within-patient correlation between paired optic nerves, yielding cluster-corrected 95% confidence intervals and p values. Patient-level comparisons were evaluated using McNemar’s test. Results CE FS 3D FLAIR detected optic disc abnormalities in 18 of 55 symptomatic nerves (32.7%) compared with 11 of 55 (20.0%) on CE FS 3D T1WI. The advanced protocol yielded higher AUC (0.93 vs. 0.88, bootstrap p value = 0.003), accuracy (90.6% vs. 80.2%), sensitivity (89.1% vs. 69.1%), and NPV (86.4% vs. 69.6%) than the standard protocol. In atypical presentations, sensitivity for definite optic neuritis improved from 50.0% (13/26) to 76.9% (20/26). Conclusions Adding CE FS 3D FLAIR to conventional orbital MRI significantly improves diagnostic accuracy for optic neuritis, especially in atypical clinical presentations.

Objectives: This study evaluated the utility of adaptive complex signal average (ACSA) diffusion-weighted imaging (DWI) specifically in breath-hold (BH) liver imaging, with a focus on signal intensity (SI) improvement, intrahepatic signal homogeneity, and apparent diffusion coefficient (ADC) behavior, and compared these findings with conventional non-ACSA DWI and free-breathing (FB) ACSA DWI. Methods: This retrospective study included 62 patients (mean age, 67.8 ± 13.6 years; 27 women) who underwent liver MRI with both FB and BH DWI on a 3-T system. Non-ACSA images were generated using conventional magnitude reconstruction, and ACSA images were reconstructed from identical raw data. SI, signal-to-noise ratio (SNR) and ADC were measured in the left lateral segment and right hepatic lobe. The signal intensity difference ratio (SIDR) between ACSA and non-ACSA, signal intensity ratio (SIR) and ADC ratio between right lobe and lateral segment were calculated. Results: In both FB and BH imaging, SI and SNR in both liver regions were significantly higher on ACSA DWI than on non-ACSA DWI (p < 0.01). ADC values were significantly lower with ACSA. SIDR was significantly higher in the left lateral segment (p < 0.01), indicating greater SI improvement in motion-prone regions. SIR and ADC ratios between lobes were significantly smaller with ACSA in both respiratory conditions (p < 0.01). FB-ACSA showed smaller SIR than BH-ACSA, while ADC ratios did not differ. Conclusions: ACSA DWI significantly improves SI, intrahepatic uniformity, and ADC reliability even under BH liver imaging. BH ACSA DWI may represent a potentially useful application complementary to FB ACSA DWI, supporting its consideration as a post-processing strategy for improving qualitative and quantitative liver DWI in future investigations.

Purpose To evaluate the feasibility of a high-precision single-shot fast spin–echo (SS-FSE) sequence using the deep learning-based Precise IQ Engine (PIQE) algorithm in comparison with standard SS-FSE for T2-weighted MR imaging of the abdomen, and to compare the image quality with a multi-shot (MS)-FSE sequence using the PIQE algorithm. Methods This retrospective study included 105 patients who underwent abdominal MR including T2-weighted sequences using the PIQE reconstruction algorithm. The image quality, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in high-precision SS-FSE sequences using PIQE were compared to those in standard SS-FSE without PIQE and MS-FSE sequences using PIQE. Results The scores for all qualitative parameters were significantly higher in high-precision SS-FSE sequence using PIQE than in standard SS-FSE sequence without PIQE (all p < 0.001). In the comparison between two high-precision sequences using PIQE, the SS-FSE sequence showed significantly better scores for the blurring, ghosts or motion/flow artifacts, conspicuity of intrahepatic structures, focal nonsolid hepatic and pancreatic cystic lesions, and overall image quality, in comparison to the MS-FSE sequence (all p < 0.001). Additionally, the SS-FSE sequence using PIQE showed significantly higher SNR of the liver and CNR of nonsolid hepatic lesions than the MS-FSE sequence using PIQE (p < 0.001). Conclusions A high-precision SS-FSE sequence using the PIQE algorithm is a feasible alternative to the standard FSE sequence in T2-weighted MR imaging of the abdomen. It can improve image quality, the SNR of the liver, and the ability to visualize nonsolid focal liver lesions and pancreatic cystic lesions in comparison to a high-precision MS-FSE sequence using PIQE although this study was limited by single-center design and lack of pathological confirmation.