The recent development of advanced high-resolution transducers has enabled the fast, easy, and dynamic ultrasonographic evaluation of small, superficial structures such as the finger. In order to best exploit these advances, it is important to understand the normal anatomy and the basic pathologies of the finger, as exemplified by the following conditions involving the dorsal, volar, and lateral sections of the finger: sagittal band injuries, mallet finger, and Boutonnière deformity (dorsal aspect); flexor tendon tears, trigger finger, and volar plate injuries (volar aspect); gamekeeper's thumb (Stener lesions) and other collateral ligament tears (lateral aspect); and other lesions. This review provides a basis for understanding the ultrasonography of the finger and will therefore be useful for radiologists.

Objectives: To assess whether virtual non-contrast (VNC) computed tomography (CT) images acquired from dual-energy CT (DECT) have sufficient image quality to replace true non-contrast (TNC) CT images in CT angiography (CTAG). Methods: This study enrolled 63 consecutive patients who underwent a CTAG that included a single-energy non-contrast scan, followed by a post-contrast DECT scan. Comparison of attenuation and noise between TNC and VNC images was made by drawing circular regions of interest (ROI) on a picture archiving and communication system (PACS) workstation within the aortic lumen at the levels of the renal arteries, the aortic bifurcation and right femoral artery. Mean attenuation and image noise (one standard deviation) were registered in Hounsfield units (HU). The VNC images were subjectively evaluated for artifacts such as subtraction of calcifications or architectural distortion based on TNC image as a standard of reference. Results: Most attenuations of the VNCs were higher than TNC, except right femoral artery of reader 2. Most image noises of TNC were higher than VNC, except abdominal aorta in reader 1. In qualitative image analysis, mean scores of VNC according to the 5-point scale were 3.68 and 3.63 (reader 1 and reader 2, respectively) which mean good to excellent to diagnose. Conclusion: HUs and VNC image noises are different from TNC images in CTAG. VNC images have sufficient image quality to replace TNC images in the diagnosis of calcific lesions. Advances in knowledge: VNC images acquired from DECT have image quality adequate to replace TNC images in the diagnosis of the calcific lesion on the CTAG. VNC images based on DECT can avoid excessive and unnecessary patient exposure to radiation during CTAG.

Purpose: This study evaluated epidermal cyst elasticity using multiple parameters of strain elastography (SE) and shear wave elastography (SWE) and assessed the reproducibility of each parameter.Methods: This retrospective study included 73 patients with epidermal cysts who underwent SE and SWE. SE scores were classified as 1-4 according to elasticity. The strain ratio was evaluated using the elasticity ratio of lesions and adjacent subcutaneous fat tissue. For SWE, the shear wave velocity (m/s), elasticity (kPa) according to the Young modulus, velocity ratio, and elasticity ratio were evaluated. All values were measured twice. The reproducibility of SE and SWE measurements was assessed. The relationships among SE and SWE measurements were evaluated.Results: The strain ratio on SE images showed good reproducibility (intra-class correlation coefficient [ICC]=0.789), and SE scores showed substantial reproducibility (kappa=0.753 and kappa=0.758 for readers 1 and 2, respectively). Moderate reproducibility was found for shear wave velocity and elasticity (ICC=0.750 and ICC=0.648, respectively), as well as for the shear wave velocity of the reference tissue and velocity ratio (ICC=0.747 and ICC=0.713, respectively). All SE scores were positively correlated with the strain ratio (P<0.001). The strain ratio in the second SE session was significantly correlated with the elasticity ratio and velocity ratio in the first SWE session (r=0.245, P=0.037; r=0.243, P=0.038, respectively). Other variables were not correlated.Conclusion: SE and SWE parameters of epidermal cysts showed moderate to good reproducibility. The strain ratio on SE showed good reproducibility and could provide relatively objective and consistent measurements of epidermal cyst elasticity.

Objective: To evaluate whether measurement of protruding anterior meniscus in the medial compartment (PAMM) and posterior tibial translation (PTT) can be used as a secondary sign of posterior cruciate ligament (PCL) tear for differential diagnosis of partial or complete tear. Methods: 21 cases with complete PCL tear, 35 cases with partial PCL tear, and 55 normal cases were reviewed in this retrospective study. PTT and PAMM were measured from the MR images associated with each case. Non-parametric data were evaluated using the Kruskal–Wallis test and the Mann–Whitney U-test with Bonferroni correction to compare differences among the three groups: complete tear, partial tear, and controls Results: There were significant differences in the median values of PAMM among the three groups, and with PAMM increasing as the grade of PCL injury increased. However, there were no significant differences in median PTT among the three groups. Median PAMM in the partial and complete tear groups was significantly higher than in subjects without PCL rupture (adjusted p-value <0.05). Although median PAMM in subjects in the complete tear group tended to be higher than in those with a partial tear, this difference was not statistically significant (adjusted p-values ≥0.418). Conclusion: PAMM is more useful finding than PTT and can predict PCL tear with or without posterior instability. However, PAMM cannot differentiate partial tear and complete tear of the PCL. Advances in knowledge: PAMM is more useful finding than PTT and can predict PCL tear with or without posterior instability. However, PAMM cannot differentiate partial tear and complete tear of the PCL.

Background/Objectives: Adult degenerative scoliosis (ADS) is a three-dimensional spinal deformity caused by asymmetric degeneration of intervertebral discs, facet joints, and paraspinal muscles (PSM). Although previous studies have identified bilateral asymmetry in the multifidus (MF), the erector spinae (ES), and psoas (PS), the underlying mechanism remains unclear. This study aims to compare muscle volume (MV), fat infiltration (FI), and degenerative changes on the concave (CC) and convex (CV) sides in symptomatic ADS patients. Methods: This study included patients with ADS who visited Kangbuk Samsung Hospital between 2022 and 2024. MV and FI were measured by CT scans, and facet joint degeneration (FJD), disc degeneration (DD), and foraminal stenosis (FS) were assessed by MRI. The values of CV and CC side were compared. Results: 74 patients were enrolled with a mean age of 71.38 ± 8.6 years. MV of all PSM was significantly lower on the CC side than CV side. FI of ES and MF was significantly higher on the CC side compared to the CV side. Degenerative changes in the intervertebral discs and neural foramen were more severe on the CC side. Conclusions: In patients with ADS, we found that MV was consistently lower on the CC side across all PSM, whereas FI in the MF and ES was higher on the CC side. Degenerative changes in the spine, such as FS and DD, were also more severe on the CC side, although FJD was not. These results suggest that spinal muscle and structural degeneration are not evenly distributed between two sides. Physiotherapy that specifically targets the more affected CC side may offer better outcomes for patients with ADS.