Neurosarcoidosis involving cervical nerve root with unusual MRI findings: a case report and systematic literature review.

BACKGROUND: Neurosarcoidosis is rare, and among its manifestations, nerve root involvement has been reported in only a few cases. Therefore, magnetic resonance imaging (MRI) findings of neurosarcoidosis, particularly those involving nerve roots, are scarce in the literature. METHODS: We presented the case of neurosarcoidosis involving cervical nerve roots and cranial nerves, alongside a systematic literature review. RESULTS: A 28-year-old female suddenly developed right facial numbness as well as left upper extremity and left hand pain. Initial brain and spine MRI showed a bulging mass of T2 iso-to-high signal intensity in the left Meckel's cave/trigeminal nerve, as well as diffuse enlargement of the right C6 and C7 nerve roots. Follow-up MRI at 2 months revealed a reduction in the size of the initial lesion and the appearance of new similar lesions on the contralateral side (right Meckel's cave, left C3-C8 nerve roots). In particular, the lesions involving the nerve roots demonstrated central enlargement along the nerve roots, without involvement of the adjacent spinal cord. All these lesions exhibited enhancement, leading to the differentiation between sarcoidosis and lymphoma. Sarcoidosis was subsequently confirmed through biopsy of a hilar lymph node. CONCLUSIONS: This report presents a distinctive MRI feature of neurosarcoidosis involving spinal nerve roots, representing the first of its kind, and describes the evolution of MRI findings throughout the clinical course.

Coronal plane in opportunistic screening of osteoporosis using computed tomography: comparison with axial and sagittal planes.

OBJECTIVE: To compare the coronal plane with axial and sagittal planes in opportunistic screening of osteoporosis using computed tomography (CT). MATERIALS AND METHODS: A total of 100 patients aged ≥ 50 years who underwent both lumbar spine CT and dual-energy X-ray absorptiometry within 3 months were included. Osteoporosis was diagnosed based on dual-energy X-ray absorptiometry results. The CT number was measured at the center of the vertebral body in coronal, axial, and sagittal planes. To compare the coronal plane with axial and sagittal planes in diagnosing osteoporosis, the areas under the receiver operating characteristic curve (AUC) were compared and intraclass correlation coefficient (ICC) was calculated. The optimal cutoff values were calculated using Youden's index. RESULTS: The AUC of the coronal plane (0.80; 95% confidence interval [CI], 0.71-0.89) was not significantly different from that of the axial plane (0.78; 95% CI, 0.68-0.87; P = 0.39) and that of the sagittal plane (0.78; 95% CI, 0.69-0.87; P = 0.68). Excellent concordance rates were observed between coronal and axial planes with ICC of 0.95 (95% CI, 0.92-0.96) and between coronal and sagittal planes with ICC of 0.93 (95% CI, 0.85-0.96). The optimal cutoff values for the coronal, axial, and sagittal planes were 110, 112, and 112 HU, respectively. CONCLUSION: The coronal plane does not significantly differ from axial and sagittal planes in opportunistic screening of osteoporosis. Thus, the coronal plane as well as axial and sagittal planes can be used interchangeably in measuring bone mineral density using CT.

Feasibility of deep learning algorithm in diagnosing lumbar central canal stenosis using abdominal CT.

OBJECTIVE: To develop a deep learning algorithm for diagnosing lumbar central canal stenosis (LCCS) using abdominal CT (ACT) and lumbar spine CT (LCT). MATERIALS AND METHODS: This retrospective study involved 109 patients undergoing LCTs and ACTs between January 2014 and July 2021. The dural sac on CT images was manually segmented and classified as normal or stenosed (dural sac cross-sectional area ≥ 100 mm2 or < 100 mm2, respectively). A deep learning model based on U-Net architecture was developed to automatically segment the dural sac and classify the central canal stenosis. The classification performance of the model was compared on a testing set (990 images from 9 patients). The accuracy, sensitivity, and specificity of automatic segmentation were quantitatively evaluated by comparing its Dice similarity coefficient (DSC) and intraclass correlation coefficient (ICC) with those of manual segmentation. RESULTS: In total, 990 CT images from nine patients (mean age ± standard deviation, 77 ± 7 years; six men) were evaluated. The algorithm achieved high segmentation performance with a DSC of 0.85 ± 0.10 and ICC of 0.82 (95% confidence interval [CI]: 0.80,0.85). The ICC between ACTs and LCTs on the deep learning algorithm was 0.89 (95%CI: 0.87,0.91). The accuracy of the algorithm in diagnosing LCCS with dichotomous classification was 84%(95%CI: 0.82,0.86). In dataset analysis, the accuracy of ACTs and LCTs was 85%(95%CI: 0.82,0.88) and 83%(95%CI: 0.79,0.86), respectively. The model showed better accuracy for ACT than LCT. CONCLUSION: The deep learning algorithm automatically diagnosed LCCS on LCTs and ACTs. ACT had a diagnostic performance for LCCS comparable to that of LCT.

Intra-individual comparison of lumbar spine CT, abdomen-pelvis contrast enhanced CT, and low-dose chest CT for bone density measurement.

BACKGROUND: Dual-energy X-ray absorptiometry (DXA) is the reference standard for the measurement of bone mineral density (BMD) and subsequent diagnosis of osteoporosis. Since various computed tomography (CT) protocols are scanned for various indications, we can incidentally measure BMD using CT. Previous studies have revealed a correlation between BMD and Hounsfield unit (HU) values obtained with different CT protocols. PURPOSE: To compare the diagnostic value of CT protocols (lumbar spine CT [LSCT], abdomen-pelvis contrast-enhanced CT [APCT], and low-dose chest CT [LDCT]) for osteoporosis. MATERIAL AND METHODS: We retrospectively included 17 patients (6 men, 11 women; mean age=68 years) who had undergone all four imaging studies within six months, during 2011-2021. HU values were manually measured at the center of the L1 vertebra by a radiology resident. Pearson correlation test was performed between HU values and BMD of L1 vertebra. The diagnostic performance of each CT protocol was assessed with receiver operating characteristic (ROC) analysis. Intra-individual concordance of the four tests to diagnose osteoporosis was analyzed by tabulating. RESULTS: The mean HU values were 104.4 ± 47.2 HU with LSCT, 149.0 ± 56.9 HU with APCT, and 114.3 ± 60.0 HU with LDCT. HU values from each protocol were positively correlated (r = 0.676-0.735; P < 0.005) with BMD. LDCT had the highest diagnostic performance (area under the ROC curve [AUC] = 0.701) and APCT the lowest (AUC = 0.569). APCT was discordant with the other protocols for diagnosing osteoporosis. CONCLUSION: LDCT had the highest diagnostic performance for osteoporosis with predetermined cutoff value. APCT requires the increase of cutoff value for osteoporosis diagnosis.

Dual-layer spectral detector CT arthrography of the shoulder: assessment of image quality and value in differentiating calcium from iodine.

BACKGROUND: Dual-layer spectral detector computed tomography (DLCT) may potentially improve CT arthrography through enhanced image quality and analysis of the chemical composition of tissue. PURPOSE: To evaluate the image quality of monoenergetic reconstructions from DLCT arthrography of the shoulder and assess the additional diagnostic value in differentiating calcium from iodine. MATERIAL AND METHODS: Images from consecutive shoulder DLCT arthrography examinations performed between December 2016 and February 2018 were retrospectively reviewed for hyperattenuating lesions within the labrum and tendons. The mean attenuation of the target lesion, noise, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) of the virtual monoenergetic images obtained at 40-200 keV were compared with conventional 140-kVp images. Two evaluators independently classified each target lesion as contrast media or calcification, without and with DLCT spectral data. Receiver operating curve (ROC) analysis was performed to assess the diagnostic performance of shoulder DLCT arthrography, without and with the aid of spectral data. RESULTS: The study included 20 target lesions (18 DLCT arthrography examinations of 17 patients). The SNRs of the monoenergetic images at 40-60 keV were significantly higher than those of conventional images (P < 0.05). The CNRs of the monoenergetic images at 40-70 keV were significantly higher than those of conventional images (P < 0.001). The ability to differentiate calcium from iodine, without and with DLCT spectral data, did not significantly differ (P = 0.441 and P = 0.257 for reviewers 1 and 2, respectively). CONCLUSION: DLCT had no additive value in differentiating calcium from iodine in small, hyperattenuating lesions in the labrum and tendons.

Interlaminar versus transforaminal epidural steroid injections: a review of efficacy and safety.

Spine intervention is an important treatment option for the management of spinal pain, and the numbers of the most representative epidural steroid injection (ESI) procedures performed are expected to increase significantly in the future along with increased life expectancy and the increasing prevalence of spinal disorders. Therefore, it is important to understand the efficacy of ESIs according to each spinal disorder they are administered to treat, and one must be familiar with the possible complications. In fact, although numerous ESI-related articles have been published, there is still considerable controversy regarding the efficacy of ESI procedures. Furthermore, due to the rarity of serious complications, most instances have been recorded in the form of case reports. In this article, we aimed to review the indications of cervical and lumbar ESIs and to compare interlaminar ESI (ILESI) and transforaminal ESI (TFESI) techniques in terms of analgesic efficacy, possible complications, and safety profiles. This article includes opinions based on the authors' experience with ESI indications and efficacy, and presents practical tips for coping with specific situations related to each complication. By combining the dedicated anatomical understanding of radiologists with image-guided interventions, ESI is expected to stand out in the rapidly expanding field of spine intervention.

Effectiveness of epidural steroid injection in patients with lumbar herniated intervertebral disc under a "wait-and-see" policy.

BACKGROUND: There are no consensus and guidelines on the optimal interval of repeat epidural steroid injections (ESI) for patients with lumbar herniated intervertebral disc (HIVD) who respond to initial ESI. PURPOSE: To evaluate the effectiveness of ESI in patients with HIVD under a "wait-and-see" policy, i.e. as-needed injections not on a predetermined schedule. MATERIAL AND METHODS: A total of 592 patients with lumbar HIVD received spine injections between January and December 2017. After excluding patients with excellent (no pain) or poor (>70% residual symptoms) response in the two- or three-week pain assessment, the data of 141 responders were analyzed (60 men, 73 women; age = 50.55±17.25 years). We divided patients into wait-and-see (n=124) and early repeat-ESI (n=17) groups, who received repeat ESIs within three weeks. Evaluations of characteristics and outcomes were performed with the chi-square test or independent Student's t-test. RESULTS: Six patients (4.8%) in the wait-and-see group and 1 (5.9%) in the early repeat-ESI group underwent operation within one year (P=0.85). A mean of 1.52±0.82 ESIs was performed in the wait-and-see and a mean of 2.29±0.47 ESIs in the early repeat-ESI group over one year (P<0.001). The time interval between the first and second ESIs was longer in the wait-and-see group than in the early repeat-ESI group (97.15 vs. 15.47 days, P<0.001). Seventy-eight patients (62.9%) in the wait-and-see group could control their pain with a single ESI. CONCLUSION: A "wait-and-see" policy could be an effective pain management option for patients with lumbar HIVD who respond to initial ESI.

Data rate enhancement of free space optical communication using pulse positioned differential phase shift keying.

In this paper, a pulse positioned-differential phase shift keying technique is proposed to enhance the data rate in free space optical communication. Using the schematics of polarization rotation differential phase shift keying, multi-rate functionality can be achieved without using delay-line interferometers. Furthermore, the proposed novel modulation format-differential phase shift keying combined with pulse-position modulation-enables a high data rate owing to the use of an average power limited amplifier. By using the average power limited amplifier, the signal power is increased as the pulse position order increases, which enhances the bit-error-rate performance. The increased signal power can be converted to an enhanced data rate. We demonstrated that the data rate above 625 Mbps can be increased in every step, as the pulse position order increases in the pulse positioned-differential phase shift keying. The performance enhancement of the proposed technique is theoretically and experimentally demonstrated.

Predicting the clinically significant subscapularis tendon tear: malposition and tear of the long head of the biceps tendon on shoulder magnetic resonance imaging.

BACKGROUND: The diagnostic accuracy of magnetic resonance imaging (MRI) is low for detecting a subscapularis tendon tear. PURPOSE: To identify MRI findings that may predict the presence of a clinically significant subscapularis tendon tear requiring surgical repair. MATERIAL AND METHODS: We reviewed shoulder MR images of patients who had undergone arthroscopic rotator cuff repair at our institution between June 2018 and May 2019. Patients were divided into two groups: the study group (n = 51), with an intermediate- to high-grade partial thickness tear of the subscapularis tendon suspected on preoperative MRI and intermediate or higher grade of the tendon tear proven on arthroscopy; and the control group (n = 18), with an intermediate- to high-grade partial thickness tear of the subscapularis tendon suspected on preoperative MRI but no tear or low-grade partial thickness tear of the tendon shown on arthroscopy. Preoperative MR images were retrospectively evaluated by two readers for the size of the subscapularis tendon tear, bone reactions at the lesser tuberosity, and long head of the biceps tendon (LHBT) pathology. RESULTS: The subscapularis tendon tear measured by reader 2 was larger in the study group than in the control group. The prevalence of a tear (P = 0.006 for reader 1; P = 0.011 for reader 2) and malposition (P < 0.001 for both readers) of the LHBT were significantly greater in the study group. CONCLUSION: A tear and malposition of the LHBT on MR images may predict the presence of a clinically significant subscapularis tendon tear.

Accurate Imputation of Greenhouse Environment Data for Data Integrity Utilizing Two-Dimensional Convolutional Neural Networks.

Greenhouses require accurate and reliable data to interpret the microclimate and maximize resource use efficiency. However, greenhouse conditions are harsh for electrical sensors collecting environmental data. Convolutional neural networks (ConvNets) enable complex interpretation by multiplying the input data. The objective of this study was to impute missing tabular data collected from several greenhouses using a ConvNet architecture called U-Net. Various data-loss conditions with errors in individual sensors and in all sensors were assumed. The U-Net with a screen size of 50 exhibited the highest coefficient of determination values and the lowest root-mean-square errors for all environmental factors used in this study. U-Net50 correctly learned the changing patterns of the greenhouse environment from the training dataset. Therefore, the U-Net architecture can be used for the imputation of tabular data in greenhouses if the model is correctly trained. Growers can secure data integrity with imputed data, which could increase crop productivity and quality in greenhouses.

Intra-articular facet joint steroid injection-related adverse events encountered during 11,980 procedures.

OBJECTIVES: To analyze the incidence and characteristics of intra-articular facet joint injection (FJI)-related adverse events requiring hospitalization and emergency room visits. METHODS: From January 2007 to December 2017, a total of 11,980 FJI procedures in 6066 patients (mean age 66.8 years, range 15-97 years, M:F = 2004:4062) were performed in our department. Of these, we retrospectively reviewed 489 cases in 432 patients who were hospitalized or visited the emergency room within a month of FJI. FJI-related adverse events were classified as procedure-related complications, drug-related systemic events, or uncertain etiology events, on the basis of consensus of two spine radiologists. This is a descriptive study without statistical analysis. RESULTS: There were 101 FJI-related adverse event cases in 99 patients (mean age 71.8 years, range 39-97 years, M:F = 39:60). The overall incidence of FJI-related adverse events was 0.84% (101/11,980) per case and 1.63% (99/6066) per patient. The incidence of procedure-related complications and drug-related systemic adverse events was 0.07% (8/11,980) and 0.15% (18/11,980), respectively; the rate of uncertain etiology events was 0.63% (75/11,980). All eight procedure-related complication cases involved major complications. There are seven cases of infectious spondylitis and one was progression of systemic aspergillosis to the spine. One patient died of an uncontrolled infection with infective endocarditis, and two patients experienced partial recovery with neurological sequelae. CONCLUSIONS: The overall incidence of FJI-related adverse events is low, and procedure-related major complications are rare without dural puncture or epidural hematoma. Nevertheless, infection can occur, resulting in serious outcomes. KEY POINTS: • The incidence of FJI-related adverse events requiring hospitalization or ER visit was 0.84%. • The incidence of major procedure-related complications was 0.07%. • All major complications were associated with infection and there were no cases of epidural hematoma.

Ruling out rotator cuff tear in shoulder radiograph series using deep learning: redefining the role of conventional radiograph.

OBJECTIVE: To develop a deep learning algorithm that can rule out significant rotator cuff tear based on conventional shoulder radiographs in patients suspected of rotator cuff tear. METHODS: The algorithm was developed using 6793 shoulder radiograph series performed between January 2015 and June 2018, which were labeled based on ultrasound or MRI conducted within 90 days, and clinical information (age, sex, dominant side, history of trauma, degree of pain). The output was the probability of significant rotator cuff tear (supraspinatus/infraspinatus complex tear with > 50% of tendon thickness). An operating point corresponding to sensitivity of 98% was set to achieve high negative predictive value (NPV) and low negative likelihood ratio (LR-). The performance of the algorithm was tested with 1095 radiograph series performed between July and December 2018. Subgroup analysis using Fisher's exact test was performed to identify factors (clinical information, radiography vendor, advanced imaging modality) associated with negative test results and NPV. RESULTS: Sensitivity, NPV, and LR- were 97.3%, 96.6%, and 0.06, respectively. The deep learning algorithm could rule out significant rotator cuff tear in about 30% of patients suspected of rotator cuff tear. The subgroup analysis showed that age < 60 years (p < 0.001), non-dominant side (p < 0.001), absence of trauma history (p = 0.001), and ultrasound examination (p < 0.001) were associated with negative test results. NPVs were higher in patients with age < 60 years (p = 0.024) and examined with ultrasound (p < 0.001). CONCLUSION: The deep learning algorithm could accurately rule out significant rotator cuff tear based on shoulder radiographs. KEY POINTS: • The deep learning algorithm can rule out significant rotator cuff tear with a negative likelihood ratio of 0.06 and a negative predictive value of 96.6%. • The deep learning algorithm can guide patients with significant rotator cuff tear to additional shoulder ultrasound or MRI with a sensitivity of 97.3%. • The deep learning algorithm could rule out significant rotator cuff tear in about 30% of patients with clinically suspected rotator cuff tear.

Association of meniscal flounce in the knee with the pattern and location of meniscal tear, concomitant ligamentous injury, amount of knee joint effusion, and flexion and rotation angles: a magnetic resonance evaluation.

OBJECTIVE: To determine the association of meniscal flounce with the pattern and location of the meniscal tear, concomitant ligamentous injury, amount of knee joint effusion, and flexion and rotation angles. MATERIALS AND METHODS: A total of 283 knees of 280 patients were retrospectively reviewed over a 9-month period. Thirty-one magnetic resonance images of patients with meniscal flounce were compared with those of age- and sex-matched control group (n = 62) without meniscal flounce. The presence of meniscal tear was evaluated and, if present, its location and pattern were recorded. The amount of joint effusion was graded, and the joint angle was measured. The Fisher's exact, Cochran-Armitage trend, and t tests were performed to compare the findings between the two groups. The decision tree analysis was employed to determine the most significant factor of meniscal flounce. RESULTS: Meniscal flounce was present in 11.0% (31/283) of the adult population. Approximately 80.6% of meniscal flounce occurred in the torn medial menisci. The presence of meniscal flounce was significantly associated with tears at the body (p = 0.007), posterior horn (p = 0.001), and meniscocapsular junction (p = 0.002) of the medial meniscus. The decision tree analysis revealed that the posterior horn tear of the medial meniscus was the most significant predictor of meniscal flounce. CONCLUSION: The most significant factor associated with meniscal flounce is tear at the posterior horn of the medial meniscus, followed by tear at the meniscocapsular junction.

Performance of a Deep Learning Algorithm in Detecting Osteonecrosis of the Femoral Head on Digital Radiography: A Comparison With Assessments by Radiologists.

OBJECTIVE. The objective of our study was to compare the sensitivity of a deep learning (DL) algorithm with the assessments by radiologists in diagnosing osteonecrosis of the femoral head (ONFH) using digital radiography. MATERIALS AND METHODS. We performed a two-center, retrospective, noninferiority study of consecutive patients (≥ 16 years old) with a diagnosis of ONFH based on MR images. We investigated the following four datasets of unilaterally cropped hip anteroposterior radiographs: training (n = 1346), internal validation (n = 148), temporal external test (n = 148), and geographic external test (n = 250). Diagnostic performance was measured for a DL algorithm, a less experienced radiologist, and an experienced radiologist. Noninferiority analyses for sensitivity were performed for the DL algorithm and both radiologists. Subgroup analysis for precollapse and postcollapse ONFH was done. RESULTS. Overall, 1892 hips (1037 diseased and 855 normal) were included. Sensitivity and specificity for the temporal external test set were 84.8% and 91.3% for the DL algorithm, 77.6% and 100.0% for the less experienced radiologist, and 82.4% and 100.0% for the experienced radiologist. Sensitivity and specificity for the geographic external test set were 75.2% and 97.2% for the DL algorithm, 77.6% and 75.0% for the less experienced radiologist, and 78.0% and 86.1% for the experienced radiologist. The sensitivity of the DL algorithm was noninferior to that of the assessments by both radiologists. The DL algorithm was more sensitive for precollapse ONFH than the assessment by the less experienced radiologist in the temporal external test set (75.9% vs 57.4%; 95% CI of the difference, 4.5-32.8%). CONCLUSION. The sensitivity of the DL algorithm for diagnosing ONFH using digital radiography was noninferior to that of both less experienced and experienced radiologist assessments.

Clinical and imaging characteristics of patients with extreme low back pain or sciatica referred for spinal injection.

PURPOSE: To analyze the causes of pain, imaging characteristics, and therapeutic effect of spinal injection in patients with extreme low back pain or sciatica. METHODS: We analyzed 381 consecutive patients with extreme low back pain or sciatica visiting our spinal intervention center between January and December 2017. Clinical and imaging characteristics were analyzed. The treatment response, defined as a numerical pain rating scale decrease of ≥ 30%, was measured. Fisher's exact test was performed to identify the association between the injection response and subsequent lumbar surgery rate. RESULTS: The most frequent cause of pain was spinal stenosis, followed by herniated intervertebral disc, facet osteoarthritis, and osteoporotic compression fracture. A herniated intervertebral disc was the most common disorder in patients < 50 years of age, while spinal stenosis was the most common in patients ≥ 50 years of age. Women comprised 66.4% of the study population. The majority of lumbar pathologies occurred below L3/4. Spinal injection was found to be effective in 44.2% of cases. Those who responded to the injection showed a significantly lower rate of lumbar surgery within 6 months (P = 0.004). CONCLUSIONS: Those with extreme low back pain or sciatica had clinical and imaging characteristics similar to those with typical low back pain referred for spinal injection. Spinal injection could be an effective method of pain control for patients with extreme low back pain or sciatica.

Non-traumatic ligamentum teres tears: association with MRI morphometry of the hip.

BACKGROUND: The ligamentum teres has been recognized as an important stabilizer of the hip. PURPOSE: We aimed to examine the relationship between non-traumatic ligamentum teres (LT) tear and hip morphometry on magnetic resonance imaging (MRI). MATERIAL AND METHODS: Fifty patients who had undergone hip MRI were included (27 men, 23 women; average age = 54.0 years). The status of the LT and the morphometric hip parameters were assessed, including acetabular anteversion angle (AAA), acetabular depth (AD), acetabular index (AI), lateral center edge angle (LCEA), and extrusion index (EI). The morphometric hip parameters were compared between groups with one-way ANOVA, Student's t-test, and Mann-Whitney U test. RESULTS: A decreased acetabular coverage was noted in the severe tear group compared to the normal group, indicated by a significantly larger AD ( P = 0.001) and smaller LCEA ( P = 0.016). There was a statistically significant difference in the AAA, AD, and LCEA between the normal group and the complete tear group; the AAA was significantly larger ( P = 0.031), the AD was significantly larger ( P = 0.01), and the LCEA was significantly smaller ( P = 0.043) in the complete tear group compared to the normal group. CONCLUSION: There is an association between LT tears and acetabular bony morphology; an insufficient acetabular coverage is associated with complete tear of the LT. As the insufficient acetabular coverage may predispose to ligamentum teres tear, the ligamentum teres should be thoroughly evaluated in those with insufficient acetabular coverage, as a potential cause of hip pain.

The pattern of idiopathic isolated teres minor atrophy with regard to its two-bundle anatomy.

OBJECTIVE: We aimed to analyze the pattern of teres minor atrophy with regard to its two-bundle anatomy and to assess its association with clinical factors. MATERIALS AND METHODS: Shoulder MRIs performed between January and December 2016 were retrospectively reviewed. Images were evaluated for the presence and pattern of isolated teres minor atrophy. Isolated teres minor atrophy was categorized into complete or partial pattern, and partial pattern was further classified according to the portion of the muscle that was predominantly affected. The medical records were reviewed to identify clinical factors associated with teres minor atrophy. RESULTS: Seventy-eight shoulders out of 1,264 (6.2%) showed isolated teres minor atrophy; complete pattern in 41.0%, and partial pattern in 59.0%. Most cases of partial pattern had predominant involvement of the medial-dorsal component (82.6%). There was no significant association between teres minor atrophy and previous trauma, shoulder instability, osteoarthritis, and previous operation. The history of shoulder instability was more frequently found in patients with isolated teres minor atrophy (6.4%), compared with the control group (2.6%), although the difference was not statistically significant. CONCLUSION: Isolated teres minor atrophy may be either complete or partial, and the partial pattern may involve either the medial-dorsal or the lateral-ventral component of the muscle. The imaging findings of partial pattern teres minor atrophy indicate that the two muscle components may have separate innervation.

Epidural steroid injection-related events requiring hospitalisation or emergency room visits among 52,935 procedures performed at a single centre.

OBJECTIVES: To analyse the incidence and type of epidural steroid injection (ESI)-related adverse events, including procedure-related complications and drug-related systemic effects requiring hospitalisation or emergency room (ER) visits. METHODS: This study included 52,935 ESI procedures performed in 22,059 patients in our department from March 2004 to February 2016. Of these, we retrospectively reviewed the cases of 1570 patients (1713 procedures) who were hospitalised or visited the ER within 1 month after ESI. ESI-related events were classified as procedure-related complications, drug-related systemic effects, or of uncertain relationship. Descriptive data are provided; no statistical analysis was performed. RESULTS: There were 244 ESI-related events in 235 patients (males:females = 102:133; mean age: 65.7 years; range: 20-93 years). The incidence of ESI-related events was 0.46% per procedure, including 14 procedure-related complications, 56 drug-related systemic effects, and 174 events of uncertain cause. Of the 52,935 patients, 6 (0.011%) experienced major complications (two spine haematomas and four infections), 1 patient died, and 1 experienced neurological sequelae. CONCLUSIONS: Although major procedure-related complications and drug-related systemic effects of ESI requiring hospitalisation are very rare, infection and haematoma can occur, resulting in serious outcomes. Hence, ESI should be carefully considered in high-risk patients. KEY POINTS: • The incidence of ESI-related events requiring hospitalisation was 0.46%. • The incidence of procedure-related complications was 0.026%. • The incidence of drug-related systemic effects was 0.11%. • The incidence of major complication of ESI was 0.011%. • The major complications were spine infection, haematoma, and sepsis.

Uncovered Medial Meniscus Sign on Knee MRI: Evidence of Lost Brake Stop Mechanism of the Posterior Horn Medial Meniscus.

OBJECTIVE: The objective of our study was to evaluate the association between anterior tibial translation and injuries on the posterior horn medial meniscus (PHMM) and the integrity of the brake stop mechanism of the PHMM in the anterior cruciate ligament (ACL)-deficient knee. MATERIALS AND METHODS: This retrospective study included 85 consecutive patients with an arthroscopically confirmed complete ACL tear. Anterior tibial translation was quantitatively measured using sagittal MRI at the midpoint of the lateral femoral condyle. The "uncovered medial meniscus" sign was considered positive if a vertical line tangent to the posteriormost margin of the medial tibial plateau intersected the PHMM at the midpoint of the medial femoral condyle on sagittal MRI. Concomitant injuries on the structures of the posteromedial and posterolateral corners of the knee, including PHMM tear and meniscal ramp lesion, were recorded. Stratified subgroup analysis and multivariable regression analysis were performed to identify factors associated with anterior tibial translation. RESULTS: The uncovered medial meniscus sign was positive in 21.2% (18/85) of patients and was significantly associated with anterior tibial translation. In the stratified subgroup analysis and multivariable regression analysis, positive uncovered medial meniscus sign consistently showed a significant association with anterior tibial translation and generated an additional 2.8 mm of anterior tibial translation. Other injuries, including PHMM tear and meniscal ramp lesion, were not associated with anterior tibial translation. CONCLUSION: The uncovered medial meniscus sign showed a statistically significant correlation with anterior tibial translation and could be a useful marker for the lost brake stop mechanism of PHMM in the ACL-deficient knee.

MR evaluation of the meniscal ramp lesion in patients with anterior cruciate ligament tear.

OBJECTIVE: To identify the findings on magnetic resonance imaging most strongly associated with meniscal ramp lesions in patients with an anterior cruciate ligament tear. SUBJECTS AND METHODS: Seventy-eight consecutive patients (mean age, 33.7 years; 64 male, 14 female) with an arthroscopically proven anterior cruciate ligament tear were included in this retrospective study. The presence of the following six features on magnetic resonance images were recorded: complete fluid filling between the posterior horn of the medial meniscus and the capsule margin; edema affecting the posterior capsule; irregularity of the medial meniscus at the posterior margin; fluid at the periphery of the medial meniscus; the corner notch sign; and a vertical tear at the medial meniscus. Findings at arthroscopy served as the reference standard. Diagnostic accuracy, sensitivity, and interobserver agreement were calculated. RESULTS: Seven ramp lesions were noted on arthroscopy (9%). Findings of irregularity at the posterior margin (p = 0.001) and complete fluid filling between the posterior horn of the medial meniscus and the capsule margin (p = 0.004) on magnetic resonance imaging were significantly associated with the presence of a ramp lesion. With the irregularity at the posterior margin, sensitivity was 86% and specificity was 79%. Complete fluid filling sign showed sensitivity of 57% and specificity of 92%. Concordance of the two readers for the six magnetic resonance imaging features was fair to very good (k = 0.38-0.91). CONCLUSIONS: Irregularity at posterior margin and complete fluid filling were most sensitive findings for detecting of a ramp lesion on magnetic resonance imaging.