Automated analysis of knee joint alignment using detailed angular values in long leg radiographs based on deep learning.

Malalignment in the lower limb structure occurs due to various causes. Accurately evaluating limb alignment in situations where malalignment needs correction is necessary. To create an automated support system to evaluate lower limb alignment by quantifying mechanical tibiofemoral angle (mTFA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA) on full-length weight-bearing radiographs of both lower extremities. In this retrospective study, we analysed 404 radiographs from one hospital for algorithm development and testing and 30 radiographs from another hospital for external validation. The performance of segmentation algorithm was compared to that of manual segmentation using the dice similarity coefficient (DSC). The agreement of alignment parameters was assessed using the intraclass correlation coefficient (ICC) for internal and external validation. The time taken to load the data and measure the four alignment parameters was recorded. The segmentation algorithm demonstrated excellent agreement with human-annotated segmentation for all anatomical regions (average similarity: 89-97%). Internal validation yielded good to very good agreement for all the alignment parameters (ICC ranges: 0.7213-0.9865). Interobserver correlations between manual and automatic measurements in external validation were good to very good (ICC scores: 0.7126-0.9695). The computer-aided measurement was 3.44 times faster than was the manual measurement. Our deep learning-based automated measurement algorithm accurately quantified lower limb alignment from radiographs and was faster than manual measurement.

Primary spontaneous pneumomediastinum: 237 cases in a single-center experience over a 10-year period and assessment of factors related with recurrence.

OBJECTIVE: To evaluate the precipitating factors and symptoms of primary spontaneous pneumomediastinum (PSPM) and to assess the factors related with recurrent spontaneous pneumomediastinum (RSPM). METHODS: From 2010 to 2021, 237 PSPM patients were included in this retrospective study. Clinical information including in-hospital periods, morbidity, mortality, presenting symptoms, precipitating events, smoking, and asthma history was obtained. The patients with smoking history were subdivided into "ex-smoker" or "current smoker". The severity of asthma was categorized into "mild intermittent", "mild persistent", "moderate persistent", or "severe persistent". During follow-up, patients with RSPM were classified into "recurrence" group and the others were into "no recurrence" group. Multivariate regression analysis was used to elucidate the associated factors with RSPM. RESULTS: The mean age of study patients (men: women = 222: 15) was 23.4 years and mean period of hospital stay was 7.5 days. There was no mortality and morbidity. Most frequent symptom and precipitating factor were acute chest pain (n = 211, 89.0%) and cough (n = 72, 30.4%), respectively. RSPM occurred in 11 patients (4.6%). The proportion of patients with smoking (72.8% vs. 37.1%, p = 0.010) or asthma (81.8% vs. 39.8%, p<0.001) was significantly higher in "recurrence" group than "no recurrence" group. On multivariate analysis, asthma was the only factor associated with RSPM (mild intermittent/persistent, OR = 7.092, p = 0.047; moderate persistent, OR = 8.000, p = 0.011). CONCLUSION: PSPM is a benign disease with no morbidity and mortality. Asthma may be the associated factor with RSPM; thus, despite the low rate of recurrence, patients with asthma should be informed about the chance of RSPM.

Feasibility and reliability of various morphologic features on magnetic resonance imaging for iliotibial band friction syndrome.

Background: To evaluate the feasibility, inter-reader reliability, and intra-reader reliability for various morphological features reported to be related to iliotibial band friction syndrome (ITBFS) on knee magnetic resonance imaging (MRI). Methods: A total of 145 patients with a clinical diagnosis and knee MRI findings consistent with ITBFS were included in the "study group" and 232 patients without knee pathology on both physical examination and MRI were included in the "control group". Various morphologic features on knee MRI were assessed including the patella shape, patella height, lateral epicondyle anterior-posterior (AP) width, lateral epicondyle height, ITB diameter (ITB-d), and ITB area (ITB-a). Results: Patients in the study group had significantly higher lateral epicondyle height (13.9 mm vs. 12.92 mm, P = 0.003), ITB-d (2.9 mm vs. 2.0 mm, P = 0.022), and ITB-a (38.5 mm2 vs. 23.8 mm2, P < 0.001) than the control group. ITB-a showed higher area under the curve index (0.849 with 74.1% sensitivity and 72.4% specificity at a 30.3 mm2 cutoff) than ITB-d (0.710 with 70.8% sensitivity and 61.2% specificity at 2.4 mm cutoff) and lateral epicondyle height (0.776 with 72.4% sensitivity and 67.8% specificity at 13.4 mm cutoff). However, only the interreader agreement for ITB-a (intraclass correlation coefficient = 0.65) was moderate, while the agreements for other morphologic features were good or excellent. Conclusions: Lateral epicondyle height seems to be a reliable and feasible morphologic feature for diagnosis of ITBFS.

Prevalence and neglected rate of sacroiliitis on lumbar spine CT in patients with low back pain.

OBJECTIVE: The study aims to investigate the prevalence and neglected rate of sacroiliitis on lumbar spine computed tomography (CT) in patients with low back pain. MATERIALS AND METHODS: From January 2016 to December 2020, a total of 4827 patients (mean age: 35.4 ± 9.5 years) who underwent lumbar spine CT examinations were included in this retrospective study. The CT degree of sacroiliitis in all study population were retrospectively reviewed by two radiologists. The independent sample t-test was used to compare the continuous values and chi-squared or Fisher's exact test was used to compare the categorized values. RESULTS: Sacroiliitis was identified in 514 of 4827 patients (10.6%). Patients with sacroiliitis were significantly younger than those without sacroiliitis (32.1 ± 8.9 vs. 35.8 ± 9.5 years, p < 0.001). Moreover, significantly more patients with sacroiliitis had HLA-B27 (p < 0.001) positivity and inflammatory back pain syndrome (p = 0.003) than those without sacroiliitis. Among the 514 patients, sacroiliitis was recognized on primary reading in 386 patients (75.1%) but was neglected in the remaining 128 patients (24.9%). Of the 386 patients, 371 patients were followed up, and finally, 295 patients of them (79.5%) were diagnosed with axSpA. CONCLUSION: Radiologists should pay careful and more attention to sacroiliac joint on lumbar spine CT for early diagnosis of sacroiliitis in young patients with low back pain, which could result in early diagnosis and treatment of axSpA.

Patella-patellar tendon angle in relation to the medial patellar plica syndrome, chondromalacia patella, and infrapatellar fat pad syndrome.

The patella-patellar tendon angle (PPTA) assessing the sagittal patellar tilt was reported to be related with anterior knee pain. Herein, clinical effect of PPTA in patients with medial patellar plica (MPP) syndrome, chondromalacia patella, and infrapatellar fat pad (IPFP) syndrome, the most common causes of anterior knee pain, was evaluated. In this retrospective study, 156 patients with anterior knee pain who underwent magnetic resonance imaging (MRI) and arthroscopic surgery that confirmed isolated MPP syndrome, chondromalacia patella, or IPFP syndrome from June 2011 to January 2021 were included in the study group and 118 patients without knee pathology on MRI during the same period were included in the control group. The PPTA was measured on knee MRI and compared between the two groups. A receiver operating characteristic (ROC) analysis was used to evaluate the value of PPTA for predicting the risk of patellofemoral joint disorder. The mean PPTA was significantly smaller in study group (138.1 ± 4.2°) than control group (142.1 ± 4.3°) (p < 0.001). However, there was no significant difference in PPTA among the patients with MPP syndrome, chondromalacia patella, and IPFP syndrome. Furthermore, the ROC analysis revealed that the area under curve, sensitivity, and specificity for predicting the risk of patellofemoral joint disorders were 0.696, 70.3% and 57.6%, respectively, at a PPTA cutoff of 138.3°. Therefore, the smaller PPTA may be associated with MPP syndrome, chondromalacia patella, and IPFP syndrome. Furthermore, PPTA could be a predictive factor for the risk of patellofemoral joint disease in patients with anterior knee pain.

The Utility of Modified Dixon Turbo Spin Echo Shoulder Magnetic Resonance Arthrography in Assessing Rotator Cuff Disorder and Evaluating the Rotator Cuff Muscles.

RATIONALE AND OBJECTIVES: To compare the diagnostic ability of modified Dixon (mDixon) turbo spin echo (TSE) T1-weighted (T1W) shoulder magnetic resonance arthrography (MRA) with that of conventional shoulder MRA, and evaluate the feasibility of mDixon TSE in-phase (IP) images in measuring the fat fraction and size of rotator cuff muscles. MATERIALS AND METHODS: This retrospective study included 57 patients who underwent 3T shoulder MRA examinations with conventional and mDixon TSE T1W images (mean age: 56.7 years; range: 20-78 years). Two musculoskeletal radiologists independently evaluated the rotator cuff tendons with fat saturated T1W images and mDixon TSE T1W water images. Occupation ratios measured on T1W and mDixon TSE T1W IP images were compared. The fat fraction of the supraspinatus from the mDixon TSE T1W images was calculated and correlated with fatty infiltration of the supraspinatus on T1W images. RESULTS: For tendon pathology, the kappa value for inter-sequence and inter-reader agreement was 0.957 (95% confidence interval [CI]: 0.923-0.990) and 0.839 (95% CI: 0.778-0.899), respectively. For retear, the kappa value for inter-sequence and inter-reader agreement was 0.913 (95% CI: 0.796-1.000) and 0.779 (95% CI: 0.594-0.963), respectively. The intraclass correlation coefficient for both occupation ratios was 0.986 (95% CI: 0.973-0.993). Comparison of mDixon TSE T1W fat fraction with Goutallier grade showed a strong positive linear correlation (r = 0.929). CONCLUSIONS: The mDixon TSE T1W sequence is a good alternative to conventional sequences in shoulder MRA for evaluating rotator cuff pathology. Furthermore, this sequence provides information on the size and fat infiltration of rotator cuff muscles.

[Optimization of MRI Protocol for the Musculoskeletal System]. / 근골격계 ìžê¸°ê³µëª ì˜ìƒ í”„ë¡œí† ì½œì˜ ìµœì í™”.

Magnetic resonance imaging (MRI) is an essential modality for the diagnosis of musculoskeletal system defects because of its higher soft-tissue contrast and spatial resolution. With the recent development of MRI-related technology, faster imaging and various image plane reconstructions are possible, enabling better assessment of three-dimensional musculoskeletal anatomy and lesions. Furthermore, the image quality, diagnostic accuracy, and acquisition time depend on the MRI protocol used. Moreover, the protocol affects the efficiency of the MRI scanner. Therefore, it is important for a radiologist to optimize the MRI protocol. In this review, we will provide guidance on patient positioning; selection of the radiofrequency coil, pulse sequences, and imaging planes; and control of MRI parameters to help optimize the MRI protocol for the six major joints of the musculoskeletal system.

Is Chest Computed Tomography Always Necessary Following Nephrectomy for Renal Cell Carcinoma? A Pilot Study in Single Tertiary Institution.

PURPOSE: We evaluated patterns of thoracic recurrence from renal cell carcinoma (RCC) following nephrectomy as a pilot study. METHODS: Data of consecutive 39 patients who had recurrent RCC in the abdomen or thorax following curative nephrectomy were evaluated. Recurrence sites were analyzed with abdomen and chest computed tomography (CT), or positron emission tomography/CT. All patients had no metastasis before initial nephrectomy. Recurrence was classified into 3 types according to the site of initially detected recurrence: (a) abdomen-only type, (b) abdomen and thorax type, and (c) thorax-only type. Vertebral level of recurrence site in the thorax-only level was investigated. University of California Los Angeles-Integrated Staging System was utilized for risk stratification (eg, low, intermediate, and high-risk). RESULTS: Rate of intermediate or high risk was 89.7% (37/39). Rate of thoracic recurrence, regardless of concurrent abdominal recurrence, was 71.8% (28/39). Rate of thorax-only type was 53.8% (21/39). In thorax-only type, median vertebral level of recurrence site was T10 (range, T3-T12), and no patient with low risk had metastasis above the T10 level alone. In intermediate or high risk, 89.2% (33/37) had at least a recurrent lesion at the level of T7 or lower. CONCLUSIONS: In low-risk patients, upper thoracic recurrence alone may be very rare after curative surgery. In majority of intermediate- or high-risk patients, initial recurrence may occur in the abdomen or lower thorax, which indicates abdomen CT covering T7 level may be an effective tool for postoperative follow-up in RCC.

How to utilize LR-M features of the LI-RADS to improve the diagnosis of combined hepatocellular-cholangiocarcinoma on gadoxetate-enhanced MRI?

OBJECTIVES: To investigate the diagnostic accuracy of each LR-M feature defined in version 2017 of the Liver Imaging Reporting and Data System (LI-RADS) and determine the optimal LR-M feature for differentiating combined hepatocellular-cholangiocarcinoma (cHCC-CCA) and hepatocellular carcinoma (HCC) on gadoxetate-enhanced magnetic resonance imaging (MRI). METHODS: Ninety-nine patients with pathologically proven cHCC-CCA (n = 33) or HCC (n = 66) after surgery were identified. Two radiologists retrospectively assessed preoperative gadoxetate-enhanced MRI for features favoring non-HCC malignancies (LR-M features) according to LI-RADS version 2017. Multivariate logistic regression analysis was performed to determine the independent differential features. The sensitivity and specificity for diagnosing cHCC-CCA were calculated for each LR-M feature. RESULTS: Targetoid appearance showed the highest sensitivity (75.8%, 95% confidence interval [CI] 60.6%, 87.3%) to correctly identify cHCC-CCA as LR-M. At least one LR-M feature was observed in 31 (93.9%) patients with cHCC-CCA and 34 (51.5%) patients with HCC. The sensitivity and specificity for diagnosing cHCC-CCA using the presence of any one of the LR-M features were 93.9% (95% CI 80.7, 98.9) and 48.5% (95% CI 41.9, 51.0), respectively. The presence of three LR-M features yielded the highest diagnostic accuracy of 80.8% (95% CI 72.1, 86.1) with a reduced sensitivity of 54.5% (95% CI 41.4, 62.5). CONCLUSION: The majority of cHCC-CCA cases can be properly categorized as LR-M when any one of the LR-M features defined in the LI-RADS version 2017 is used as a determiner. However, approximately half of HCC cases also show at least one LR-M feature. KEY POINTS: • Targetoid appearance, including rim APHE, peripheral "washout" appearance, and delayed central enhancement, was the LR-M feature that identified cHCC-CCA as a non-HCC malignancy with the highest sensitivity. • Most cHCC-CCA cases can be properly categorized as LR-M when the presence of any one of the LR-M features was used as the determiner. • Approximately half of HCC cases also showed at least one LR-M feature.

Effectiveness of automatic tube potential selection with tube current modulation in coronary CT angiography for obese patients: Comparison with a body mass index-based protocol using the propensity score matching method.

BACKGROUND: Reduced image quality from increased X-ray scatter and image noise can be problematic when coronary computed tomography angiography (CCTA) imaging is performed in obese patients. The aim of this study was to compare the image quality and radiation dose obtained using automatic tube potential selection with tube current modulation (APSCM) with those obtained using a body mass index (BMI)-based protocol for CCTA in obese patients. METHODS: A total of 203 consecutive obese (BMI > 30 kg/m2) patients were retrospectively enrolled, of whom 96 underwent CCTA with APSCM and 107 underwent a BMI-based protocol. After applying the propensity score matching method, the clinical parameters, subjective and objective image quality, and radiation dose were compared between the APSCM group and the matched BMI-based group. These parameters were also compared among different tube potential subgroups. RESULTS: No significant differences were observed between the APSCM group and the BMI-based group with respect to image quality or radiation dose assessment (p > 0.05). Twenty patients (21%) examined with 140 kV in the APSCM group were exposed to significantly more radiation (p < 0.05) than patients in the BMI-based group or patients in the other APSCM kV subgroups; significant improvement in image quality was not observed in the 140 kV subgroup. Patients with a high BMI and a large effective diameter tended to be examined with 140 kV (p < 0.05). CONCLUSION: The use of APSCM for CCTA in obese patients did not significantly reduce the radiation dose or improve image quality compared with those in the matched BMI-based group. Our data indicate that it is better to avoid using APSCM when 140 kV is automatically selected, due to increased radiation dose and lack of significant improvement in image quality.