Diagnostic performance of electron-density dual-energy CT in detection of cervical disc herniation in comparison with standard gray-scale CT and virtual non-calcium images.

OBJECTIVES: To assess the diagnostic performance of dual-energy CT (DECT) with electron-density (ED) image reconstruction compared with standard CT (SC) and virtual non-calcium (VNCa) image CT reconstruction for detecting cervical disc herniation. METHODS: This cross-sectional study was approved by the IRB. We enrolled 64 patients (336 intervertebral discs from C2/3 to C7/T1; mean age, 55 years; 17 women and 47 men) who underwent DECT with spectral reconstruction and 3-T MRI within 2 weeks between January 2018 and June 2020. Four radiologists independently evaluated the first image set of randomized SC, VNCa, and ED images to detect cervical disc herniation. After 8 weeks, the readers re-evaluated the second and the last image sets with an 8-week interval. MRI evaluations performed by two other experienced served as the reference standard. Comparing diagnostic performance between each images set was evaluated by a generalized estimating equation. RESULTS: A total of 233 cervical disc herniations were noted on MRI. For detecting cervical disc herniation, electron-density images showed higher sensitivity (94% [219/233; 95% CI, 90-97] vs. 76% [177/233; 70-81] vs. 69% [160/233; 62-76]) (p < 0.001) and similar specificity (90% [93/103; 83-95] vs. 89% [92/103; 82-96] vs. 90% [93/103; 83-95]) (p > 0.05) as SC and VNCa images, respectively. Inter-reader agreement for cervical disc herniation calculated among the four readers was moderate for all image sets (κ = 0.558 for ED, κ = 0.422 for SC, and κ = 0.449 for VNCa). CONCLUSION: DECT with ED reconstruction can improve cervical disc herniation detection and diagnostic confidence compared with SC and VNCa images. KEY POINTS: • Intervertebral discs with high material density are well visualized on electron-density images obtained from dual-energy CT. • Electron-density images showed much higher sensitivity and diagnostic accuracy than standard CT and virtual non-calcium images for the detection of cervical disc herniation. • Electron-density images can have false-negative results, especially for disc herniation with high signal intensity on T2W images and can show pseudo-disc extrusion at the lower cervical spine.

Imaging appearance of post-arthroscopic radiocarpal chondrolysis: comparison with osteoarthritis associated with scapholunate dissociation.

BACKGROUND: Since the diagnosis of post-arthroscopic chondrolysis is very difficult, it can be underdiagnosed and confused with other diseases in clinical practice. PURPOSE: To propose imaging features of post-arthroscopic radiocarpal chondrolysis (PRCC) and to compare these with osteoarthritis associated with scapholunate dissociation which are the most common misdiagnoses of PRCC. MATERIAL AND METHODS: To identify missed diagnoses of PRCC, 994 magnetic resonance imaging scans performed in 910 patients were retrospectively reviewed. After the identification of 73 patients who exhibited significant radiocarpal cartilage loss, 11 were diagnosed with PRCC. Since scapholunate advanced collapse was the most common incorrect diagnosis of PRCC (4/11), the imaging findings were compared among the 11 patients with PRCC and 14 patients with osteoarthritis caused by scapholunate dissociation who were diagnosed in the same period. The following imaging features were evaluated: scapholunate dissociation; the center of disease and grade of radiocarpal joint destruction; characteristics of bone marrow edema; the presence of radial styloid and distal scaphoid osteophytes; and the extent of joint effusion and synovitis. RESULTS: The imaging diagnosis of PRCC was significantly differentiated from osteoarthritis associated with scapholunate dissociation based on occurrence at a younger age, bone marrow edema crossing the joint, center of disease in the proximal radioscaphoid joint, and absence of radial styloid and scaphoid osteophytes (P < 0.05). PRCC occasionally presented with arch-shape bone marrow edema based on the proximal carpal row. CONCLUSION: The diagnosis of PRCC can be aided if its characteristic imaging findings are differentiated from other disease entities in patients with a history of arthroscopy.

Additive values of pelvic tomosynthesis in comparison to pelvic radiography alone for the diagnosis of sacroiliitis in patients with suspected axial spondyloarthritis.

OBJECTIVES: To compare inter-reader agreement and diagnostic confidence in detecting sacroiliitis by the modified New York criteria (mNY) on digital radiography (DR) versus digital pelvic tomosynthesis assisted DR (DR+DPT), and to evaluate changes in the presence of axial spondyloarthritis (axSpA) according to the Assessment of Spondyloarthritis International Society (ASAS) criteria. METHODS: One hundred and thirty-eight patients who underwent both DR and DPT with suspicious axSpA in our rheumatologic clinic were included from February 2017 to February 2018. Three radiologists independently graded sacroiliitis and confidence level on DR first and then re-graded them on DPT in a paired manner. Agreement, confidence, and diagnostic accuracy were evaluated for readers. Changes in the presence of disease by mNY and ASAS criteria were assessed between DR alone and DR+DPT. RESULTS: On DR alone, 73 patients were assessed with radiographic sacroiliitis, and 85 were classified into axSpA by the ASAS criteria; however, 78 and 85, respectively, were classified on DR+DPT. With the assistance of DPT, 17 and 12 patients changed to the disease positivity according to the mNY and ASAS criteria, respectively; the negative results changed to positive in 11 and six patients, respectively. For all readers, agreement improved with DPT (0.79 to 0.89). DR+DPT achieved higher diagnostic accuracy (AUC, P < 0.05). CONCLUSION: The combination of DR and DPT achieved a higher diagnostic performance than that of DR alone, with better agreement. On DR+DPT, the diagnoses of 9.0% of patients with suspicious axSpA (12 of 134) were changed to the status of disease by the ASAS criteria.

The correlation between follow-up MRI findings and laboratory results in pyogenic spondylodiscitis.

BACKGROUND: Although MRI is the gold-standard imaging method in the diagnosis of spondylodiscitis, role of follow-up imaging is debated and there can be discrepancies with regard to the significance of bony or soft tissue responses to treatment. Purpose of our study is to test whether the MRI changes on follow-up imaging correlate with laboratory findings of treatment response. METHODS: A total of 48 patients with pyogenic spondylodiscitis who underwent baseline and follow-up MRI were retrospectively reviewed. The extent of bone marrow edema, paravertebral soft tissue inflammation, and disc height were compared on baseline and follow-up MRIs with the C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) levels obtained from the medical records at baseline and on follow-up. Relationships between the MRI and laboratory changes were analyzed using the Spearmann correlation test. RESULTS: The mean MRI follow-up period was 42.25 days. Based on the CRP (resolved: n = 19, resolving: n = 19, and aggravated: n = 10), there was significant correlation between the laboratory results and the changes in the bone and soft tissues (p < 0.01, both). The correlation was best with soft tissue changes (rho: 0.48) followed by bony changes (rho: 0.41). Based on the ESR (resolved: n = 8, resolving: n = 22, and worsened: n = 18), the correlation was stronger with bone changes (rho: 0.45, p < 0.01) than it was with soft tissue changes (rho: 0.39, p = 0.01). CONCLUSION: Follow-up MRI findings of pyogenic spondylodiscitis show variable tissue responses. CRP was best correlated with soft tissue changes, while ESR showed the best association with bony changes.

Contrast-enhanced Magnetic Resonance Imaging of Pelvic Bone Metastases at 3.0 T: Comparison Between 3-dimensional T1-weighted CAIPIRINHA-VIBE Sequence and 2-dimensional T1-weighted Turbo Spin-Echo Sequence.

OBJECTIVE: This study aimed to compare 3-dimensional T1-weighted gradient-echo sequence (CAIPIRINHA-volumetric interpolated breath-hold examination [VIBE]) with 2-dimensional T1-weighted turbo spin-echo sequence for contrast-enhanced magnetic resonance imaging (MRI) of pelvic bone metastases at 3.0 T. METHODS: Thirty-one contrast-enhanced MRIs of pelvic bone metastases were included. Two contrast-enhanced sequences were evaluated for the following parameters: overall image quality, sharpness of pelvic bone, iliac vessel clarity, artifact severity, and conspicuity and edge sharpness of the smallest metastases. Quantitative analysis was performed by calculating signal-to-noise ratio and contrast-to-noise ratio of the smallest metastases. Significant differences between the 2 sequences were assessed. RESULTS: CAIPIRINHA-VIBE had higher scores for overall image quality, pelvic bone sharpness, iliac vessel clarity, and edge sharpness of the metastatic lesions, and had less artifacts (all P < 0.05). There was no significant difference in conspicuity, signal-to-noise ratio, or contrast-to-noise ratio of the smallest metastases (P > 0.05). CONCLUSIONS: Our results suggest that CAIPIRINHA-VIBE may be superior to turbo spin-echo for contrast-enhanced MRI of pelvic bone metastases at 3.0 T.

Multiparametric MR Imaging of Age-related Changes in Healthy Thigh Muscles.

Purpose To use multiparametric magnetic resonance (MR) imaging to assess for and establish age-related differences in healthy thigh muscles. Materials and Methods Ninety-five subjects (47 men, 48 women; median age, 47 years) with healthy body mass index were grouped according to age: 30-39 years (n = 25), 40-49 years (n = 25), 50-59 years (n = 25), and 60-69 years (n = 20). Multiparametric MR imaging (intravoxel incoherent motion diffusion-weighted, diffusion-tensor, multiecho Dixon, and dynamic contrast material-enhanced MR imaging) was performed at 3.0 T. Two radiologists independently evaluated parametric maps of the anterior, medial, and posterior compartments. Welch-modified one-way analysis of variance and post hoc Dunnet T3 test were used to evaluate differences in apparent diffusion, true diffusion, and pseudodiffusion coefficients; perfusion fraction; fractional anisotropy (FA); fat percentage; volume transfer constant; constant efflux rate from the extravascular-extracellular space to plasma; volume fraction of the extravascular-extracellular space (Ve); incremental area under the curve; and Pearson and Spearman correlation coefficients were used to evaluate relationship strength. Multiple regression analysis was performed to identify independent predictors of age, and interrater reliability was assessed with intraclass correlation coefficients. Results There were significant differences among the age groups in apparent diffusion coefficients (P = .010), true diffusion coefficients (P = .045), FA (P < .001), Ve (P = .029) of the anterior compartment muscles, and fat percentages of all three compartments (P ≤ .001). Moreover, FA (Pearson r = 0.428, Spearman ρ = 0.431; P < .001) and Ve (r = 0.226, P = .030 and ρ = 0.309, P = .003) in the anterior compartment and fat percentages in all three compartments (r = 0.481, 0.475, and 0.573; ρ = 0.515, 0.487, and 0.667; respectively; P < .001) were positively associated with age. Multiple regression analysis showed that age was predictive of fat percentage in the posterior compartment (ß = 0.500, P < .001) and of FA in the anterior compartment (ß = 0.194, P = .042). Interrater reliability was excellent (intraclass correlation coefficient, 0.745-0.992). Conclusion Multiple MR imaging parameters were significantly associated with age in thigh muscles. © RSNA, 2017 Online supplemental material is available for this article.

The predictive value of MRI in the syndesmotic instability of ankle fracture.

OBJECTIVE: Although many types of ankle fracture can be combined with syndesmosis injury, preoperative imaging studies rarely reveal instability of the syndesmosis. This study assessed the use of magnetic resonance imaging (MRI) for syndesmotic instability in patients with unstable ankle fracture. METHODS: A total of 74 patients who were treated for Lauge-Hansen supination external rotation/Weber B type fracture or pronation external rotation/Weber C type fracture and who underwent MRI for preoperative assessment were enrolled. The MRI findings of the syndesmotic ligament and the results of an intraoperative stress test were evaluated. RESULTS: Twenty-six patients had a positive result on the intraoperative stress test for syndesmotic instability. The MRI findings of the syndesmotic ligaments revealed that complete tear of the posterior inferior tibiofibular ligament (PITFL) was the most reliable predictor of syndesmotic instability (sensitivity, 74%; specificity, 78%; positive predictive value, 54%). Interobserver agreement for the intraoperative stress test and MRI assessment was excellent, except for the MRI findings of the interosseous ligament (62% agreement; kappa, 0.3). CONCLUSIONS: Complete tear of the PITFL on MRI has additional diagnostic value for syndesmotic instability in ankle fracture. However, because the sensitivity might not be sufficient to justify the costs associated with MRI, cost-effectiveness should be considered.

Intravoxel incoherent motion (IVIM) analysis of vertebral bone marrow changes after radiation exposure from diagnostic imaging and interventional procedures.

Background High cumulative radiation dose in cancer patients warrants systemic examination of possible changes in bone marrow. Purpose To assess retrospectively changes in vertebral bone marrow diffusion and perfusion using intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in hepatocellular carcinoma (HCC) patients after exposure to radiation from diagnostic imaging and interventional procedures. Material and Methods A total of 21 IVIM-DWI sets in 20 HCC patients, consisting of baseline and follow-up liver magnetic resonance imaging (MRI) with an interval less than 100 days, were reviewed after varying levels of radiation exposure from transarterial chemoembolization (TACE), multiphase liver CT, and abdominal radiography. IVIM parameters (apparent diffusion coefficient [ADC], true diffusion coefficient [D], pseudodiffusion coefficient [D*], and perfusion fraction [PF]) of vertebral bone marrow were analyzed for significant differences between baseline and follow-up MRI using Wilcoxon signed-rank test, and for correlations with cumulative effective dose, as well as time interval between last radiation exposure and follow-up MRI using Spearman's correlation. Results Compared to baseline MRI, ADC, D*, and PF significantly decreased on follow-up MRI (ADC: median [interquartile range], 0.405 × 103 mm2/s [0.364-0.477] versus 0.390 [0.348-0.461]; D*: 24.011 [18.141-29.584] versus 20.815 [15.022-28.347]; PF: 10.960% [8.828-12.985] versus 9.125 [8.606-12.803]) ( P < 0.05). There was no significant difference in D ( P = 0.807). Cumulative effective dose was moderately correlated with decrease in D* (r = 0.434). In addition, longer intervals between last exposure and follow-up MRI showed negative correlations with changes in D and ADC (r = -0.352 and -0.333, respectively). Conclusion Vertebral bone marrow diffusion and perfusion parameters were significantly changed after exposure to medical radiation.

Magnetic resonance elastography (MRE) for measurement of muscle stiffness of the shoulder: feasibility with a 3 T MRI system.

BACKGROUND: Magnetic resonance elastography (MRE) at 3 T MR has the potential to improve the objective detection of skeletal muscle stiffness. PURPOSE: To determine the feasibility of MRE using 3 T MR for measurement of the stiffness of shoulder muscles in subjects. MATERIAL AND METHODS: This study prospectively evaluated 16 healthy subjects (mean age, 29.8 years; range, 25-51 years). MRE was acquired with 3 T MR through the use of a 2D-gradient-echo-based MRE sequence at two different excitation frequencies (90 and 120 Hz). The mean stiffness values (MSV) of the trapezius and infraspinatus muscles were measured by two radiologists. Differences between the MSV in the x, y, and z motion-sensitization directions were assessed. Inter-observer agreement was also measured. RESULTS: The MSV of the trapezius muscle were 2.72 kPa ± 0.6 (SD) at 90 Hz and 4.66 kPa ± 1.2 at 120 Hz, while the MSV for the infraspinatus muscle were 3.2 kPa ± 0.52 at 90 Hz and 4.38 kPa ± 0.92 at 120 Hz. The MSV for both muscles were significantly higher at 120 Hz than at 90 Hz (P < 0.05). The MSV in the three different directions were significantly different from each other in the infraspinatus muscle (P < 0.05). Levels of inter-observer agreement regarding MSV were good to excellent for both the trapezius (intraclass correlation coefficient [ICC] = 0.979-0.996) and infraspinatus muscles (ICC = 0.614-0.943). CONCLUSION: MRE at 3 T is a feasible technique for the evaluation of shoulder muscle stiffness. Extended application of skeletal muscle MRE at 3 T will contribute to the evaluation and treatment of skeletal muscle disorders.

Hoffmann's disease: MR imaging of hypothyroid myopathy.

Hoffmann's syndrome is a hypothyroid myopathy presenting as muscle stiffness and hypertrophy. It is a rare complication of hypothyroidism. MRI features of this syndrome have seldom been described in the literature. We present a case of Hoffmann's syndrome in a 34-year-old man who underwent lower extremity contrast-enhanced MRI. MRI can demonstrate the hypertrophic configuration, T2 hyperintensity, and enhancement of the involved muscles in Hoffmann's syndrome. Along with clinical, laboratory, and electromyography findings, MRI may be helpful in distinguishing between inflammatory myopathy, myonecrosis, subacute muscle denervation, and infectious myositis.

Ultrasound elastography of lateral epicondylosis: clinical feasibility of quantitative elastographic measurements.

OBJECTIVE: The objective of our study was to investigate the clinical feasibility of ultrasound elastography for assessing patients with lateral epicondylosis and to establish an objective and quantitative method of elastographic measurement in the affected tendon. SUBJECTS AND METHODS: A total of 97 symptomatic and 89 asymptomatic common extensor tendons from both elbows of 79 consecutive patients with lateral epicondylosis and 14 healthy participants were prospectively examined by gray-scale sonography, color Doppler sonography, and compression-based elastography. Real-time color-coded elastography was performed and quantified with two regions of interest: the adjacent subcutis (S1) for a reference area and the common extensor tendon (S2) for the target area. The mean strain ratio (S1/S2) was used for quantitative comparisons. The difference in the mean strain ratio between symptomatic and asymptomatic tendons was assessed with conditional regression analysis. RESULTS: In symptomatic elbows, 87 of 97 tendons (89.7%) showed intratendinous hypoechogenicity, 86 of 97 (88.7%) showed swelling, and 70 of 97 tendons (72.2%) showed intratendinous hyperemia. Color-coded elastography revealed a soft area on 73 of 97 tendons (75.3%). The mean strain ratio was 1.45 (SD, 0.45) for symptomatic tendons and 2.07 (SD, 0.70) for asymptomatic tendons. The mean strain ratio of the symptomatic tendons was significantly lower than that of asymptomatic tendons (p < 0.001), indicating that the symptomatic tendons were softer. CONCLUSION: Our results revealed that patients with lateral epicondylosis had significantly lower strain ratios in their common extensor tendon origins. Ultrasound elastography using quantitative strain ratio measurements could be a promising supplementary method to evaluate tendon abnormalities in lateral epicondylosis.

Analysis of intradiscal cement leakage during percutaneous vertebroplasty: multivariate study of risk factors emphasizing preoperative MR findings.

OBJECTIVE: Previous reports have shown that intradiscal cement leakage during percutaneous vertebroplasty (PVP) is related to several risk factors. The purpose of this study was to evaluate preoperative MRI scans for such risk factors. METHODS: The study retrospectively analyzed 136 patients (aged 43-93 years; 234 vertebral bodies) with osteoporotic compression fractures. All patients underwent both MRI and PVP. There were 28 men (20.59%) and 108 women (79.41%). Age, gender, bone mineral density (BMD) score, endplate cortical disruption, abnormal T2-weighted hyperintensity in adjacent discs, presence of Kümmell's disease, linear body fracture with extension to endplate, level of treated vertebral body and injected cement volume were considered risk factors for intradiscal cement leakage. RESULTS: Of the 234 vertebral bodies, 55 bodies from 42 patients with no endplate cortical disruption showed no adjacent intradiscal cement leakage. Of 179 bodies from 95 patients with endplate cortical disruption, 54 (30.17%) showed intradiscal cement leakage. Of the other possible risk factors, abnormal T2 hyperintensity in adjacent discs was significantly related to intradiscal cement leakage (P = 0.016). The other possible factors (age, gender, BMD score, Kümmell's disease, linear body fracture extending to the endplate, level of treated vertebral body and injected cement volume) were not related to intradiscal cement leakage. CONCLUSION: There was no adjacent intradiscal cement leakage without endplate cortical disruption. Abnormal T2 hyperintensity in adjacent discs may be related to intradiscal cement leakage, but only in the presence of endplate cortical disruption. Also, not having Kümmell's disease did not prevent intradiscal cement leakage. Thus, given these circumstances, careful cement injection is needed to reduce intradiscal cement leakage.

Evaluation of deep learning-based quantitative computed tomography for opportunistic osteoporosis screening.

To evaluate diagnostic efficacy of deep learning (DL)-based automated bone mineral density (BMD) measurement for opportunistic screening of osteoporosis with routine computed tomography (CT) scans. A DL-based automated quantitative computed tomography (DL-QCT) solution was evaluated with 112 routine clinical CT scans from 84 patients who underwent either chest (N:39), lumbar spine (N:34), or abdominal CT (N:39) scan. The automated BMD measurements (DL-BMD) on L1 and L2 vertebral bodies from DL-QCT were validated with manual BMD (m-BMD) measurement from conventional asynchronous QCT using Pearson's correlation and intraclass correlation. Receiver operating characteristic curve (ROC) analysis identified the diagnostic ability of DL-BMD for low BMD and osteoporosis, determined by dual-energy X-ray absorptiometry (DXA) and m-BMD. Excellent concordance were seen between m-BMD and DL-BMD in total CT scans (r = 0.961/0.979). The ROC-derived AUC of DL-BMD compared to that of central DXA for the low-BMD and osteoporosis patients was 0.847 and 0.770 respectively. The sensitivity, specificity, and accuracy of DL-BMD compared to central DXA for low BMD were 75.0%, 75.0%, and 75.0%, respectively, and those for osteoporosis were 68.0%, 80.5%, and 77.7%. The AUC of DL-BMD compared to the m-BMD for low BMD and osteoporosis diagnosis were 0.990 and 0.943, respectively. The sensitivity, specificity, and accuracy of DL-BMD compared to m-BMD for low BMD were 95.5%, 93.5%, and 94.6%, and those for osteoporosis were 88.2%, 94.5%, and 92.9%, respectively. DL-BMD exhibited excellent agreement with m-BMD on L1 and L2 vertebrae in the various routine clinical CT scans and had comparable diagnostic performance for detecting the low-BMD and osteoporosis on conventional QCT.

Clinical validation of a deep-learning-based bone age software in healthy Korean children.

PURPOSE: Bone age (BA) is needed to assess developmental status and growth disorders. We evaluated the clinical performance of a deep-learning-based BA software to estimate the chronological age (CA) of healthy Korean children. METHODS: This retrospective study included 371 healthy children (217 boys, 154 girls), aged between 4 and 17 years, who visited the Department of Pediatrics for health check-ups between January 2017 and December 2018. A total of 553 left-hand radiographs from 371 healthy Korean children were evaluated using a commercial deep-learning-based BA software (BoneAge, Vuno, Seoul, Korea). The clinical performance of the deep learning (DL) software was determined using the concordance rate and Bland-Altman analysis via comparison with the CA. RESULTS: A 2-sample t-test (P<0.001) and Fisher exact test (P=0.011) showed a significant difference between the normal CA and the BA estimated by the DL software. There was good correlation between the 2 variables (r=0.96, P<0.001); however, the root mean square error was 15.4 months. With a 12-month cutoff, the concordance rate was 58.8%. The Bland-Altman plot showed that the DL software tended to underestimate the BA compared with the CA, especially in children under the age of 8.3 years. CONCLUSION: The DL-based BA software showed a low concordance rate and a tendency to underestimate the BA in healthy Korean children.

T2 Black Synovitis in Musculoskeletal MRI: Disease Spectrum and Imaging Characteristics of Joint Diseases

The synovium may be affected by a wide spectrum of disorders, including inflammatory, infectious, degenerative, traumatic, hemorrhagic, and tumorous conditions. Magnetic resonance imaging (MRI) is a valuable imaging modality to characterize synovial disorders. Most abnormal lesions appear as areas of nonspecific high signal intensity on T2-weighted images (T2-WI) due to high water content or increased perfusion. However, T2 hypointensity can be attributed to blood components of varying ages, calcification, inorganic crystals, fibrosis, caseous necrosis and/or amyloid deposition. Hypointense lesions on T2-WI are infrequent and additional clinical and imaging characteristics can help to limit the list of differential diagnoses, which may include tenosynovial giant cell tumor, synovial chondromatosis, rheumatoid arthritis, tuberculous arthritis, chronic tophaceous gout, amyloid arthropathy, synovial hemangioma, lipoma arborescens and hemosiderotic synovitis. Recently, susceptibility weighted imaging has been developed and may contribute to more accurate diagnosis for deoxygenated blood and calcium. We review the MRI features of hypointense synovial lesions on MRI and emphasize the characteristic findings that suggest a correct diagnosis.

New proposed clinico-radiologic and molecular criteria in hypochondroplasia: FGFR 3 gene mutations are not the only cause of hypochondroplasia.

We applied a comprehensive set of clinical and radiological criteria for the diagnosis of hypochondroplasia (HCH) in 160 patients with short stature 58 of whom were diagnosed to have HCH. Taking into account the genotypic and phenotypic variations in HCH, we conducted a study with these 58 patients and tested them for mutations in the fibroblast growth factor receptor 3 (FGFR3) and the short stature homeobox (SHOX) gene. We characterized the phenotypes by clinical and radiologic findings. In the patients with HCH, 19 were included in Group I (FGFR3 mutations-mutations of definite significance), and 39 were in Group II (6 SHOX mutations and 33 negative for disease-causing FGFR3 mutations). The clinical findings were similar in two groups regardless of the presence or absence of mutations. More than 95% of the patients had mesomelic proportions. In Group I, the radiological findings of mesomelia of upper and lower limbs and, L1/L4 ratio in anterior-posterior and lateral view were more typical than in Group II. This study proposes comprehensive clinico-radiological criteria for the diagnosis of HCH, which would help in detecting the true incidence of this underdiagnosed condition. The presence of SHOX mutations suggest genotypic-phenotypic overlap between HCH and Leri-Weill dyschondrosteosis, though further investigation is needed to effectively elucidate the importance of these mutations. Also, the 56.9% of HCH patients with negative mutations for FGFR3 suggests that there are other undiscovered gene mutations associated with this phenotypic entity.

Extraskeletal Osteochondroma in the Posterior Neck of a Middle-Aged Female: A Case Report.

Extraskeletal osteochondroma, a variant of chondroma, typically arises in the para-articular location of hands and feet. It is a rare disease and is particularly uncommon when joint components are not involved or localized away from joints. Herein, we report a case of extraskeletal osteochondroma in the posterior neck of a 66-year-old female. The characteristic radiologic finding of our case is presented, along with the typical findings of the disease and review of related literature reports.

Lumbar Spine Computed Tomography to Magnetic Resonance Imaging Synthesis Using Generative Adversarial Network: Visual Turing Test.

(1) Introduction: Computed tomography (CT) and magnetic resonance imaging (MRI) play an important role in the diagnosis and evaluation of spinal diseases, especially degenerative spinal diseases. MRI is mainly used to diagnose most spinal diseases because it shows a higher resolution than CT to distinguish lesions of the spinal canals and intervertebral discs. When it is inevitable for CT to be selected instead of MR in evaluating spinal disease, evaluation of spinal disease may be limited. In these cases, it is very helpful to diagnose spinal disease with MR images synthesized with CT images. (2) Objective: To create synthetic lumbar magnetic resonance (MR) images from computed tomography (CT) scans using generative adversarial network (GAN) models and assess how closely the synthetic images resembled the true images using visual Turing tests (VTTs). (3) Material and Methods: Overall, 285 patients aged ≥ 40 years who underwent lumbar CT and MRI were enrolled. Based on axial CT and T2-weighted axial MR images from 285 patients, an image synthesis model using a GAN was trained using three algorithms (unsupervised, semi-supervised, and supervised methods). Furthermore, VTT to determine how similar the synthetic lumbar MR images generated from lumbar CT axial images were to the true lumbar MR axial images were conducted with 59 patients who were not included in the model training. For the VTT, we designed an evaluation form comprising 600 randomly distributed axial images (150 true and 450 synthetic images from unsupervised, semi-supervised, and supervised methods). Four readers judged the authenticity of each image and chose their first- and second-choice candidates for the true image. In addition, for the three models, structural similarities (SSIM) were evaluated and the peak signal to noise ratio (PSNR) was compared among the three methods. (4) Results: The mean accuracy for the selection of true images for all four readers for their first choice was 52.0% (312/600). The accuracies of determining the true image for each reader's first and first + second choices, respectively, were as follows: reader 1, 51.3% and 78.0%; reader 2, 38.7% and 62.0%, reader 3, 69.3% and 84.0%, and reader 4, 48.7% and 70.7%. In the case of synthetic images chosen as first and second choices, supervised algorithm-derived images were the most often selected (supervised, 118/600 first and 164/600 second; semi-supervised, 90/600 and 144/600; and unsupervised, 80/600 and 114/600). For image quality, the supervised algorithm received the best score (PSNR: 15.987 ± 1.039, SSIM: 0.518 ± 0.042). (5) Conclusion: This was the pilot study to apply GAN to synthesize lumbar spine MR images from CT images and compare training algorithms of the GAN. Based on VTT, the axial MR images synthesized from lumbar CT using GAN were fairly realistic and the supervised training algorithm was found to provide the closest image to true images.

External validation of deep learning-based bone-age software: a preliminary study with real world data.

Artificial intelligence (AI) is increasingly being used in bone-age (BA) assessment due to its complicated and lengthy nature. We aimed to evaluate the clinical performance of a commercially available deep learning (DL)-based software for BA assessment using a real-world data. From Nov. 2018 to Feb. 2019, 474 children (35 boys, 439 girls, age 4-17 years) were enrolled. We compared the BA estimated by DL software (DL-BA) with that independently estimated by 3 reviewers (R1: Musculoskeletal radiologist, R2: Radiology resident, R3: Pediatric endocrinologist) using the traditional Greulich-Pyle atlas, then to his/her chronological age (CA). A paired t-test, Pearson's correlation coefficient, Bland-Altman plot, mean absolute error (MAE) and root mean square error (RMSE) were used for the statistical analysis. The intraclass correlation coefficient (ICC) was used for inter-rater variation. There were significant differences between DL-BA and each reviewer's BA (P < 0.025), but the correlation was good with one another (r = 0.983, P < 0.025). RMSE (MAE) values were 10.09 (7.21), 10.76 (7.88) and 13.06 (10.06) months between DL-BA and R1, R2, R3 BA. Compared with the CA, RMSE (MAE) values were 13.54 (11.06), 15.18 (12.11), 16.19 (12.78) and 19.53 (17.71) months for DL-BA, R1, R2, R3 BA, respectively. Bland-Altman plots revealed the software and reviewers' tendency to overestimate the BA in general. ICC values between 3 reviewers were 0.97, 0.85 and 0.86, and the overall ICC value was 0.93. The BA estimated by DL-based software showed statistically similar, or even better performance than that of reviewers' compared to the chronological age in the real world clinic.

A Systematic Approach to Diagnosing Arthritis Based on Radiological Imaging.

Radiology plays a key role in the diagnosis of arthritis. We herein suggest an algorithmic approach to diagnosing arthritis. First, the number of joint involvements is reviewed. Monoarticular arthritis includes septic arthritis, pigmented villonodular synovitis, and synovial chondromatosis. Second, polyarticular arthritis can be categorized by its characteristics: erosive, productive, and mixed. Erosive disease includes rheumatoid arthritis, hemophilia, and amyloidosis, while productive disease includes osteoarthritis and hemochromatosis. Third, mixed diseases are subcategorized by symmetricity. Ankylosing spondylitis and inflammatory bowel disease related arthritis affect joints symmetrically, while psoriatic arthritis, reactive arthritis, and crystalline arthropathy are asymmetric. Adjacent soft tissue density, periostitis, and bone density are ancillary findings that can be used as additional differential diagnostic clues. The final step in identifying the type of arthritis is to check whether the location is a site frequently affected by one particular disease over another. This systematic approach would be helpful for radiologists in diagnosing arthritis.