Feasibility of the fat-suppression image-subtraction method using deep learning for abnormality detection on knee MRI.

Purpose: To evaluate the feasibility of using a deep learning (DL) model to generate fat-suppression images and detect abnormalities on knee magnetic resonance imaging (MRI) through the fat-suppression image-subtraction method. Material and methods: A total of 45 knee MRI studies in patients with knee disorders and 12 knee MRI studies in healthy volunteers were enrolled. The DL model was developed using 2-dimensional convolutional neural networks for generating fat-suppression images and subtracting generated fat-suppression images without any abnormal findings from those with normal/abnormal findings and detecting/classifying abnormalities on knee MRI. The image qualities of the generated fat-suppression images and subtraction-images were assessed. The accuracy, average precision, average recall, F-measure, sensitivity, and area under the receiver operator characteristic curve (AUROC) of DL for each abnormality were calculated. Results: A total of 2472 image datasets, each consisting of one slice of original T1WI, original intermediate-weighted images, generated fat-suppression (FS)-intermediate-weighted images without any abnormal findings, generated FS-intermediate-weighted images with normal/abnormal findings, and subtraction images between the generated FS-intermediate-weighted images at the same cross-section, were created. The generated fat-suppression images were of adequate image quality. Of the 2472 subtraction-images, 2203 (89.1%) were judged to be of adequate image quality. The accuracies for overall abnormalities, anterior cruciate ligament, bone marrow, cartilage, meniscus, and others were 89.5-95.1%. The average precision, average recall, and F-measure were 73.4-90.6%, 77.5-89.4%, and 78.4-89.4%, respectively. The sensitivity was 57.4-90.5%. The AUROCs were 0.910-0.979. Conclusions: The DL model was able to generate fat-suppression images of sufficient quality to detect abnormalities on knee MRI through the fat-suppression image-subtraction method.

Thumb Pronation Angle in Thumb Opposition Evaluated by the Nail Tip Angle of Thumb-Ring Finger Opposition.

BACKGROUND: This study aimed to devise the method for the evaluation of the thumb pronation angle and calculate its reference value. METHODS: The study was conducted from October 2021 to March 2022, and 600 hands of 300 healthy volunteers were included in this study. The participants were divided into 6 age groups with 50 participants each. In study 1, 12 participants from group 1 were randomly selected, which included 6 male and 6 female participants. We measured the thumb pronation angle using FASTRAK system and the nail tip angle of thumb-ring finger opposition (T-R angle) and also evaluated the relation between them. In study 2, we measured the T-R angle of 600 hands of 300 healthy volunteers. The T-R angle mean (SD) and 95% confidence interval (CI) of each age group were calculated as reference values. RESULTS: The thumb pronation angle was correlated with the T-R angle. The T-R angle mean (SD) and 95% CI of the 6 groups were as follows: group 1, 142.5° (12.4) and 117.7 to 167.3; group 2, 139.9° (10.1) and 119.7 to 160.1; group 3, 142.3° (9.7) and 122.9 to 160.5; group 4, 140.2° (12.6) and 115.0 to 165.4; group 5, 138.3° (11.9) and 114.5 to 162.1; and group 6, 135.4° (13.0) and 109.4 to 161.4. The 95% CI tended to decrease with an increasing age. CONCLUSIONS: The T-R angle was a suitable evaluation method for the thumb pronation angle, and it should be evaluated by age groups.

A Case of an Splenic Artery Aneurysm and Focal Nodular Hyperplasia Associated with an Abdominal Vascular Abnormality of Hereditary Hemorrhagic Telangiectasia.

In October 2021, a 51-year-old woman developed a skin rash. Abdominal computed tomography revealed a large splenic artery aneurysm and an intrahepatic portovenous shunt. As her splenic artery aneurysm was at risk of rupture, she was referred to the Kindai University Hospital and underwent coiling surgery. In October 2023, approximately two years after she had been initially referred, contrast-enhanced ultrasound revealed findings suggestive of focal nodular hyperplasia. No reports have confirmed the occurrence of liver masses in patients with hereditary hemorrhagic telangiectasia, which is considered to be an interesting finding when investigating the mechanism of tumor development.

Evaluating Hip Periprosthetic Joint Infection with Metal-artifact-reduction MR Imaging.

PURPOSE: To evaluate the significant findings of hip periprosthetic joint infection (PJI) using metal-artifact-reduction (MAR) MRI and to compare the MRI results to other clinical markers. METHODS: The results of MRI, including two-dimensional fast-spin echo sequences with increased bandwidth and multi-acquisition variable-resonance image combination selective for hips with orthopedic implants at 1.5T (from April 2014 to November 2021), were retrospectively assessed for imaging findings and diagnostic impressions by two radiologists. Clinical data and courses were also investigated. Univariate and multivariate analyses were performed to identify the significant MRI findings in patients with hip PJI and those who underwent surgical intervention. The MRI impressions were compared with other clinical markers in diagnosing hip PJI. RESULTS: Thirty-seven hip joints in 24 Asian patients (age = 73.9 ± 10.8 years; 18 females) were included. Twelve hip joints (32%) had PJI; seven underwent a surgical intervention. The significant findings for hip PJI included periosteal edema of the acetabulum, intermuscular edema, intramuscular fluid collection, and lymphadenopathy (P < 0.05). In the cases with surgical intervention, the significant findings included capsular distension, capsular thickening, an osteolysis-like pattern of the femur, subcutaneous fluid collection, and lymphadenopathy (P < 0.05). The MRI impressions had high diagnostic significance for both hip PJI cases and those with surgical intervention (P < 0.001). The MRI impression was more significant for hip PJI than the other clinical markers (P < 0.05), while the other clinical markers were more significant in the cases with surgical intervention (P < 0.05). CONCLUSION: The significant findings in the hip PJI cases included acetabular periosteal edema, intermuscular edema, intramuscular fluid collection, and lymphadenopathy. The significant findings in the cases with surgical intervention included capsular distention, capsular thickening, a femoral osteolysis-like pattern, subcutaneous fluid collection, and lymphadenopathy. The utilization of MAR MRI demonstrated great diagnostic significance for hip PJI.