Atsuo Inoue

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.

This study investigated the feasibility of both a reduced radiation dose and a 50% of contrast dose in multiphasic CT of the liver with a 70 kVp protocol compared with a standard-tube-voltage protocol derived from dual-energy (DE) CT (blended DE protocol) with a full-dose contrast-agents in the same patient group. This study included 46 patients who underwent multiphasic contrast-enhanced dynamic CT of the liver with both a 70 kVp and a blended DE protocols. For quantitative analysis, median CT values for the liver, aorta, and portal vein, as well as signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), were measured and calculated. In addition, as a qualitative analysis, the contrast effect and overall image quality of the abdominal organs were evaluated on a five-point scale. CNR and SNR of the hepatic parenchyma were not significantly different between the 70kV protocol and the Blended DE protocol in all phases. The 70 kVp protocol showed significantly better image quality compared with the blended DE protocol in the arterial phase (p = 0.035) and the equilibrium layer phase (p = 0.016). A 70 kVp CT protocol in combination with a reduced radiation dose and half-dose iodine load is feasible for multiphasic dynamic CT of the liver by maintaining the contrast enhancement effects and image quality in comparison with the blended DE CT protocol.