Preoperative Meniscus: Pitfalls and Traps to Avoid.

To accurately interpret knee MRI, it is important not only to know the basic meniscal anatomy but also to distinguish it from that under pathological conditions. Thus, it would be helpful to know the normal meniscus variants (false positives) that could be mistaken for meniscal tears, and tears that could easily be missed and incorrectly diagnosed as normal (false negatives). False positives include synovial recesses, meniscal flounce, the relationship between the popliteus tendon and lateral meniscus, transverse ligament, the anterior root of the meniscus, and meniscofemoral ligament. False negatives include focal radial tears, flap tears, posterior root tears, meniscocapsular separation, and discoid meniscal tears. In this pictorial essay, we reviewed the imaging data obtained in the aforementioned cases.

Multiple myeloma with intractable lumbar pain and diagnostic challenge with MRI: A case report.

We present a 63-year-old male patient with intractable bone pain and rapidly progressive osteoporosis, who was diagnosed with multiple myeloma (MM) by CT despite normal magnetic resonance imaging (MRI) findings. The gold standard diagnostic modality for MM is MRI as it can be used to sensitively evaluate bone marrow, however, the current case highlights that MRI is not always accurate in evaluating MM. CT in combination with MRI could be used for secondary osteoporosis with intractable bone pain in order to determine the diagnosis, treatment, and prognosis.

[Clinical Features and Radiological Differential Diagnoses of Symptomatic Sesamoid Bones and Accessory Ossicles: A Pictorial Essay]. / 증상이 있는 ì¢ ìžê³¨ê³¼ 부골의 ìž„ìƒì  소견과 ì˜ìƒì  감별진단: 임상화보.

Sesamoid bones and accessory ossicles are normal anatomic variants with varying morphological appearances and incidences. They are usually small osseous fragments with well-corticated margins located adjacent to the joint space and bone. Patients with sesamoid bones and accessory ossicles are usually asymptomatic and commonly encountered in clinical practice. These sesamoids and accessory bones are occasionally painful because of fractures, dislocations, degenerative changes, avascular necrosis, accessory bone infections, or abnormalities of the adjacent tissue, such as nerve entrapment, tenosynovitis, or soft tissue impingement. This article aimed to illustrate the imaging features of symptomatic sesamoids bones and accessory ossicles at various anatomic locations and describe their clinical features and radiological differential diagnosis.

Parosteal Lipoma Associated with a Growing Osteochondroma of the Right Ilium.

Parosteal lipoma is a rare type of lipoma, the incidence being approximately 0.3% of all lipomas. Moreover, parosteal lipoma coexisting with osteochondroma is extremely rare. A few cases with coexistence of osteochondroma and parosteal lipoma have been reported and they were thought to be reactive changes of adjacent bone by parosteal lipoma. However, temporal relationship of these tumors could not be explained. Here, we report a case of parosteal lipoma associated with osteochondroma of the right ilium developed over 6 years, with follow-up radiographs.

Assessment of postoperative acromial and subacromial morphology after arthroscopic acromioplasty using magnetic resonance imaging.

OBJECTIVE: To identify the morphological characteristics of the acromion and subacromial bursal space after arthroscopic acromioplasty using magnetic resonance imaging (MRI). MATERIALS AND METHODS: One hundred patients who received arthroscopic rotator cuff repair and acromioplasty each received at least three MRI examinations (preoperative, first immediate postoperative, and second follow-up imaging between 8 months and 1 year postoperatively). Changes over time in the thickness and morphology of the postoperative acromion as well as the subacromial bursal space were assessed. Clinical and radiological parameters were also analyzed to identify any association with changes in acromial morphology. RESULTS: Despite minimal acromial thinning observed at the first immediate postoperative state, the acromions showed significant thinning at the second postoperative MRI, with a mean reduction of 32%. Along with acromial thinning, an exaggerated concave contour of the acromial undersurface was observed in some patients. In the subacromial space, a loculated fluid collection developed in 91% of the patients at the second postoperative follow-up. No statistically significant association was noted between postoperative acromial thickness change and clinical or radiological factors (P value > 0.05). CONCLUSION: A significant delayed reduction in acromial thickness within approximately 1 year of arthroscopic acromioplasty is thought to be a normal postoperative feature. The simultaneous collection of a loculated, cyst-like fluid in the subacromial bursal space may be an important associated factor of postoperative acromial thinning.

The prevalence of Baker cyst in relation to the arrangement pattern between the medial head of gastrocnemius tendon and the semimembranosus tendon.

PURPOSE: The purpose of this study was to investigate whether Baker cyst (BC) was related to the specific arrangement of the medial head of gastrocnemius tendon (MHGT) and the semimembranosus tendon (SMT). MATERIALS AND METHODS: Patients who underwent knee MRI with "Baker cyst" in PACS from August 2017 to February 2018 were included in this study. Patients who did not have BC in a knee MRI performed during the same period were included in the control group. A total 210 patients were selected for inclusion in this study. For the imaging analysis, the arrangement pattern between MHGT and SMT was classified into three types: type 1, concave; type 2, flat; and type 3, convex. When imaging analysis was performed, the amount of effusion, the presence of osteoarthritis, and major ligament and meniscal tears were also described. Univariate and multivariate logistic regression analyses were performed. Statistical significance was considered at p < 0.05. RESULTS: The frequency of types 1, 2, and 3 was statistically significant depending on the presence or absence of BC (p < 0.001). The frequency of type 3 was the highest in the presence of BC, while that of type 1 was the highest in the absence of BC. BC was more common in type 2 (OR = 2.54; 95% CI = 1.27-5.07) and type 3 (OR = 4.09; 95% CI = 1.88-8.89). CONCLUSION: BC is more likely to occur in patients with SMT having a convex shape for MHGT. KEY POINTS: • Based on axial image of MRI only, one can predict which patients are morphologically more prone to develop a Baker cyst. • On axial images of MRI, Baker cyst is more likely to occur in patients with semimembranosus tendon having a convex shape for medial head of gastrocnemius tendon. • Baker cyst is not associated with the amount of effusion, OA, or internal derangement.

Shear-Wave and Strain Ultrasound Elastography of the Supraspinatus and Infraspinatus Tendons in Patients with Idiopathic Adhesive Capsulitis of the Shoulder: A Prospective Case-Control Study.

OBJECTIVE: To compare the elasticity of the supraspinatus tendon (SST) and infraspinatus tendon (IST) in patients with idiopathic adhesive capsulitis of the shoulder (ACS) with those in the control groups and to evaluate the relationship between age and tendon elasticity. MATERIALS AND METHODS: The Institutional Review Board approved this prospective, case-control study, which was conducted between November 2017 and March 2018, and informed consent was obtained from all participants. Control groups comprised healthy individuals or those with asymptomatic contralateral shoulders. Twenty-five shoulders in 20 participants in the ACS group (14 women; 53.5 ± 7.9 years) and 24 shoulders in 18 participants in the control group (6 women; 52.6 ± 10.5 years) were included. Elastography was performed in the oblique coronal plane at the neutral shoulder position. Mean/maximum/minimum velocity and stiffness from the shear-wave ultrasound elastography (SWE) and strain ratio (subcutaneous fat/target-tendon) from the strain ultrasound elastography (SE) of the SST and IST were evaluated. Statistical analyses were performed using the Mann-Whitney U test, receiver operating characteristic (ROC) curve, and Spearman correlation. RESULTS: Both velocity and stiffness in SWE were higher, and the strain ratio in SE was lower in participants with symptomatic shoulders than in those with normal shoulders (p < 0.001). SST- and IST-mean velocity, mean stiffness, and strain ratios showed excellent area under the ROC curve (> 0.970). The elastic modulus was little correlated with age (ρ = -0.340-0.239). CONCLUSION: SWE and SE indicated that SST and IST were stiffer in patients with ACS than in those with normal shoulders regardless of aging.

Systematic review and meta-analysis of magnetic resonance imaging features for diagnosis of adhesive capsulitis of the shoulder.

OBJECTIVES: To perform a systematic review and meta-analysis to identify magnetic resonance imaging (MRI) features that will aid in the diagnosis of adhesive capsulitis of the shoulder (ACS) and provide a summary of the diagnostic accuracy of the identified features METHODS: The MEDLINE and EMBASE databases were searched for studies assessing the diagnostic accuracy of MRI features of ACS. Overlapping descriptors used to denote the same imaging finding in different studies were subsumed under a single feature. The pooled accuracy including the diagnostic odd ratios (DORs) with 95% confidence intervals (CIs) of the identified features was calculated using a bivariate random-effects model. RESULTS: In total, 15 studies were included, and 74 overlapping descriptors were subsumed under six features. All six features were found to be informative for ACS diagnosis [coracohumeral ligament thickening: DOR, 13; 95% CI, 6-29; fat obliteration of the rotator interval (RI): DOR, 8; 95% CI, 3-24; RI enhancement: DOR, 44; 95% CI, 14-141; axillary joint capsule enhancement: DOR, 52; 95% CI, 27-98; inferior glenohumeral ligament (IGHL) hyperintensity: DOR, 31; 95% CI, 8-115; IGHL thickening: DOR, 28; 95% CI, 11-70]. The sensitivity and specificity of enhancement of the RI and axillary joint capsule and IGHL hyperintensity were > 80%. CONCLUSIONS: Six informative MRI features for ACS diagnosis were identified in this study with RI and axillary joint capsule enhancement and IGHL hyperintensity showing the highest diagnostic accuracy. Informative features observed on non-arthrogram MRI can be as helpful as features observed on direct magnetic resonance arthrography for ACS diagnosis. KEY POINTS: • Six informative MRI features for ACS diagnosis were identified (diagnostic odds ratio > 1). • RI and axillary joint capsule enhancement and IGHL hyperintensity showed high sensitivities/specificities (> 80%). • The use of non-arthrogram MRI is recommended for ACS diagnosis.

Comparison of acetabular and femoral morphologies on hip, pelvic, and lumbar radiographs.

PURPOSE: To evaluate the reliability of the parameters for acetabular/femoral pathomorphologies in L-spine and hip radiographs compared to pelvic radiographs. METHODS: A retrospective review of L-spine, hip, and pelvic radiographs from 101 patients was performed. Three radiologists independently measured five parameters (acetabular roof angle of Tönnis [Tönnis angle], center-edge-angle of Wiberg [CEA], femoral head extrusion index [FHEI], cross-over sign, pistol-grip deformity) in each radiograph. RESULTS: No significant differences were identified (p ≥ 0.07) except Tönnis angles and FHEIs from the L-spine radiographs. Inter-radiograph/inter-reader ICCs were excellent or good. CONCLUSION: Pathomorphology-related measurements in L-spine radiographs can also be used as alternatives to those in pelvic or hip radiographs. If L-spine radiographs are already available, additional pelvic or hip radiographs may be unnecessary, thus reducing patients' overall radiation exposure.

Comparison between 3D isotropic and 2D conventional MR arthrography for diagnosing rotator cuff tear and labral lesions: A meta-analysis.

BACKGROUND: Although 3D-isotropic MR arthrography has been characterized as a substitute imaging tool for rotator cuff tear (RCT) and labral lesions, it has not been commonly used in clinical practice because of controversy related to image blurring and indistinctness of structural edges. PURPOSE: To perform a comparison of the diagnostic performance of 3D-isotropic MR arthrography and 2D-conventional MR arthrography for diagnosis of RCT (solely RCT, full/partial-thickness supraspinatus [SST]-infraspinatus [IST] tear, or subscapularis [SSc] tear) and labral lesions. STUDY TYPE: Meta-analysis. POPULATION: Patients with shoulder pain. FIELD STRENGTH/SEQUENCE: 3D-isotropic and 2D-conventional MR arthrography at 3.0T or 1.5T. ASSESSMENT: PubMed and EMBASE were searched following the PRISMA guidelines. STATISTICAL TESTS: Bivariate modeling and hierarchical summary receiver operating characteristic modeling were performed to compare the overall diagnostic performance of 3D-isotropic and 2D-conventional MR arthrography. Multiple-subgroup analyses were performed for diagnosing RCT, full/partial-thickness SST-IST tear, SSc tear, and labral lesions. Meta-regression analyses were performed according to subject, study, and MR arthrography characteristics including 3D-isotropic sequences (turbo spine echo [TSE] vs. gradient echo [GRE]). RESULTS: Eleven studies (825 patients) were included. Overall, 3D-isotropic MR arthrography had similar pooled sensitivity (0.90 [95% CI, 0.87-0.93]) (P = 0.95) and specificity (0.92 [95% CI, 0.87-0.95]) (P = 0.99), relative to 2D-conventional MR arthrography (sensitivity, 0.91 [95% CI, 0.86-0.94]); specificity, 0.92 [95% CI, 0.87-0.95]). Multiple-subgroup analyses showed that sensitivities (P = 0.13-0.91) and specificities (P = 0.26-0.99) on 3D-isotropic MR arthrography for diagnosing RCT, full/partial-thickness SST-IST tear, SSC tear, and labral lesions were not significantly different from 2D-conventional MR arthrography. On meta-regression analysis, 3D-TSE sequence demonstrated higher sensitivity (P < 0.01) than 3D-GRE for RCT and labral lesions. DATA CONCLUSION: 3D-isotropic MR arthrography can replace 2D-conventional MR arthrography. 3D-isotropic MR arthrography using TSE sequence is recommended for more accurate diagnosis, as it demonstrates increased sensitivity. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;48:1034-1045.

Perineural Spread Along Spinal and Obturator Nerves in Primary Vaginal Carcinoma: A Case Report.

BACKGROUND: Perineural spread is not an uncommon feature in carcinoma of the head and neck. On the contrary, perineural spread in pelvic malignancies has been rarely reported. This is the first report on perineural spread of the obturator nerve and the lumbosacral plexus from primary vaginal cancer. CASE DESCRIPTION: A 50-year-old woman diagnosed with infectious spondylitis at an outside hospital was referred to our institution. She presented with persistent lower back pain and right anterior thigh pain. Magnetic resonance imaging and subsequent 18F-fluorodeoxyglucose-positron emission tomography/computed tomography revealed primary vaginal cancer with metastatic lymphadenopathy and perineural spread of the lumbosacral plexus, including L3, L4 nerve roots and branches, and obturator nerve along with soft tissue masses in the right psoas and proximal adductor muscles. CONCLUSIONS: Clinical diagnosis of perineural spread in pelvic malignancies is difficult to establish, as it has nonspecific symptoms as an initial manifestation. Clinicians should recognize the possibility of perineural spread of malignancies if radiologic findings, such as thickening of lumbosacral nerves and perineural mass, are observed on magnetic resonance imaging. Further evaluation is necessary to detect possible pelvic malignancy and differentiate from other diseases.

Efficacy of double inversion recovery magnetic resonance imaging for the evaluation of the synovium in the femoro-patellar joint without contrast enhancement.

OBJECTIVE: To investigate the efficacy of double inversion recovery (DIR) sequence for evaluating the synovium of the femoro-patellar joint without contrast enhancement (CE). METHODS: Two radiologists independently evaluated the axial DIR and CE T1-weighted fat-saturated (CET1FS) images of 33 knees for agreement; the visualisation and distribution of the synovium were evaluated using a four-point visual scaling system at each of the five levels of the femoro-patellar joint and the location of the thickest synovium. The maximal synovial thickness at each sequence was measured by consensus. RESULTS: The interobserver agreement was good (κ = 0.736) for the four-point scale, and was excellent for the location of the thickest synovium on DIR and CET1FS (κ = 0.955 and 0.954). The intersequential agreement for the area with the thickest synovium was also excellent (κ = 0.845 and κ = 0.828). The synovial thickness on each sequence showed excellent correlation (r = 0.872). CONCLUSION: The DIR showed as good a correlation as CET1FS for the evaluation of the synovium at the femoro-patellar joint. DIR may be a useful MR technique for evaluating the synovium without CE. KEY POINTS: • DIR can be useful for evaluating the synovium of the femoro-patellar joint. • Interobserver and intersequential agreements between DIR and CET1FS were good. • Mean thickness of the synovium was significantly different between two sequences.

Predictive Factors of Retear in Patients With Repaired Rotator Cuff Tear on Shoulder MRI.

OBJECTIVE: This study aimed to find independent prognostic factors related to retear of the rotator cuff tendon in patients with repaired full-thickness supraspinatus tendon tear by evaluation of pre- and postoperative MR images. MATERIALS AND METHODS: Shoulder MR images were retrospectively analyzed for 83 patients who had undergone arthroscopic or open rotator cuff repair with acromioplasty for full-thickness supraspinatus tendon tear from April 2014 to March 2015. On preoperative MR images, the type of rotator cuff tear, extent of retraction of torn tendon, anteroposterior (AP) dimension of torn tendon, signal intensity of tear edge, degree of fat infiltration in supraspinatus and infraspinatus muscles, and acromiohumeral interval (AHI) were assessed. Postoperative cuff integrity seen on MR images was classified into five categories according to the Sugaya classification system, and patients were categorized into retear or intact groups. Factors assessed on preoperative MR images were compared between the two groups. RESULTS: The overall retear rate was 57.8%. Significant differences were observed between the retear and intact groups in terms of the mean values of the extent of tendon retraction (20.4 vs 11.7 mm), AP dimension of the tear (16.1 vs 11.4 mm), AHI (6.8 vs 8.7 mm), and degree of fat infiltration of the supraspinatus and infraspinatus muscles (for the supraspinatus muscle, 3, 30, and 15 patients in the retear group vs 5, 27, and three patients in the intact group had Goutallier grade 1, grade 2, and grades 3 and 4 infiltration, respectively; for the infraspinatus muscle, 27, 12, and 9 patients in the retear group vs 29, 5, and one patient in the intact group had Goutallier grade 1, grade 2, and grades 3 and 4 infiltration, respectively). Multivariable analysis revealed that AHI and degree of tendon retraction were independent predictive factors affecting retear of rotator cuff after repair. CONCLUSION: The retear rate of repaired rotator cuff tendon was about 57.8%. Independent prognostic factors of retear were degree of tendon retraction and AHI on preoperative MR images.

Validity of Radiograph-Based Infrapatellar Fat Pad Opacity Grading for Assessing Knee Synovitis: Correlation With Contrast-Enhanced MRI.

OBJECTIVE: The purpose of this study was to determine the validity of infrapatellar fat pad (IPFP) opacity grading based on lateral knee radiography for assessing knee synovitis using correlation with contrast-enhanced (CE) MRI. MATERIALS AND METHODS: Retrospective reviews of radiographs and CE knee MR images from 79 patients were independently performed by two radiologists. They evaluated IPFP opacity alteration (IPFPCR) and joint effusion grades on lateral knee conventional radiographs, IPFP signal intensity alteration (IPFPMR) and joint effusion grades on CE MR images, and synovitis (SYNMR) grade in nine divided regions, three compartments (parapatellar, periligamentous, perimeniscal), and the whole knee on CE MR images. Correlations between radiographic grades and MRI assessments were evaluated using Spearman correlation tests, and the correlation coefficients (ρ) were compared. Interobserver agreement was evaluated using weighted kappa values. RESULTS: The IPFPCR grade was very highly correlated with the IPFPMR grade (ρ = 0.906, p < 0.001) and highly correlated with SYNMR grades from four regions (suprapatellar, infrapatellar, intercondylar, lateral parapatellar recess), the parapatellar compartment, and the whole knee (ρ = 0.614-0.740, all p < 0.001). The IPFPCR grade was moderately correlated with the SYNMR grades of the remaining five regions and two compartments (ρ = 0.457-0.547, all p < 0.001). The differences between correlation coefficients for SYNMR grades and the IPFPCR and IPFPMR grades were not statistically significant (p = 0.290-1.0). Interobserver reliabilities were excellent or good for IPFPCR, IPFPMR, and SYNMR grades (κ = 0.661-1.000). CONCLUSION: IPFPCR grade assessment enables valid evaluation and reporting of knee synovitis, especially in the parapatellar compartment and the whole knee.

A Focal Defect at the Lateral Patellar Retinaculum on Clinical Knee MRI and Cadaveric Study: A Normal Variant or Pathologic Lesion?

OBJECTIVE: The purpose of this study is to retrospectively investigate the frequency of a focal defect at the lateral patellar retinaculum on knee MRI and to determine the variables that are significantly associated with the defect. MATERIALS AND METHODS: Two radiologists independently reviewed 99 knee MR images for the presence of a focal defect at the lateral patellar retinaculum and categorized patients with concordant results into two groups: a group with the defect (≥ 3 mm; group 1) and a group without the defect (< 3 mm; group 2). Clinical and radiologic variables, including the Kellgren-Lawrence radiographic grade, subcutaneous fat thickness, infrapatellar fat pad area, and the amount of joint effusion, were evaluated. The size and location of the defect were measured in group 1. To correlate MRI and histologic findings, MRI was performed for 11 cadavers, and three histologic specimens were obtained. RESULTS: Of the 99 knee MR images, concordant results between two reviewers were obtained for a total of 96 knees (97%): 25 knees (26%) in group 1 and 71 knees (74%) in group 2. A statistically significant difference between groups (p = 0.033) was noted for the infrapatellar fat pad area only. In all three cadaveric specimens, the lateral patellar retinaculum was more loose and sparse than the medial patellar retinaculum, and this site corresponded to the location of the defect on MRI. CONCLUSION: A focal defect of the lateral patellar retinaculum was not found to be a rare finding on knee MRI (frequency, 26%), and it may be a normal variant rather than a pathologic change. In addition, we suspect that a focal defect can be a route of infrapatellar fat herniation and a route of superficial extension of the infrapatellar fat pad lesion without a lateral patellar retinaculum tear or invasion.

Bilateral bony fusion around the supraspinatus muscle inducing muscle hypoplasia and shoulder pain.

We describe the case of a 30-year-old man who developed chronic bilateral shoulder pain that relapsed and remitted over the course of 1 year. The patient was diagnosed with congenital shoulder fusion anomalies. The right shoulder showed anomalous accessory articulation between the distal third of the clavicle and the acromion along with normal articulation of the shoulder on CT. At the left shoulder, bony fusions were present between the distal portion of the clavicle, the acromion, and the coracoid process, and between the coracoid process, upper portion of the glenoid, and upper body of the scapula, which formed a bony canal and was responsible for hypoplasia of the supraspinatus muscle on CT and MRI. To our knowledge, this is the first description of such congenital shoulder anomalies with extreme bony fusion and is an illustrative example of how imaging may be used to differentiate fusion from other congenital abnormalities of the shoulder to aid diagnosis.

Invagination of intra-abdominal structures in the lumbar intervertebral disc space.

Invagination of peritoneal or retroperitoneal structures into the intervertebral disc space of the lumbar spine is extremely rare. In this article the imaging features and clinical findings are demonstrated in four patients with intervertebral invagination of intra-abdominal structures. Plain radiographs, CT scans, and MR images showed disruption of the anterior ligamentous complex (ALC) and invagination of various structures into the disc space, including the vena cava, iliac vessels, intestine, the torn redundant anterior longitudinal ligament, retroperitoneal fat, and the psoas muscle. The invaginations occurred at the level of L3-L4 and L4-L5 in one case each and at L5-S1 in two cases. Follow-up imaging in three cases (1, 5, and 8 years respectively) showed the progression of the invagination. These cases demonstrate that a close evaluation of this condition is necessary, particularly for older patients who show disruption or laxity of the ALC, degenerative spondylosis with chronic segmental instability, and osteoporosis of the lower lumbar spine.

Amyloid Arthropathy of the Hip Joint Associated with Multiple Myeloma: A Case Report.

Amyloidosis is a disease characterized by the deposition of non-soluble fibrous protein in multiple tissues with a number of possible causes. This protein deposition can occur in any tissue, yet is most commonly seen in kidneys, heart, and gastrointestinal tracts. However, invasion to bone tissues is not often reported. The deposition of amyloid proteins in bone tissues may result in joint pain and pathological fractures; it is important to elucidate the causes and detect early to determine prognosis and treat optimally. In the present case report, with relevant literature review, the authors report a case of total hip arthroplasty in an amyloidosis patient.

Imaging findings of various talus bone tumors-clinico-radiologic features of talus bone tumors.

Osseous neoplasms of the foot are uncommon, accounting for only 3.3% of all primary bone tumors. Bone tumors of the talus are even rarer, and there are not many publications that comprehensively evaluate the imaging findings of talus tumors. The purpose of this article is to review the benign and malignant bone tumors affecting this uncommon site and to describe the clinical and radiologic features of each tumor.