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.

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.

Clinical Features and Radiological Differential Diagnoses of Symptomatic Sesamoid Bones and Accessory Ossicles: A Pictorial Essay

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.

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 0.970). 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.

Magnetic Resonance-Based Grading of Psoas and Paraspinal Muscle Edema: Is It Helpful in Diagnosing Lumbar Transverse Process Fractures?

PURPOSE@#To determine the reliability of edema grading of the psoas and paraspinal muscles on axial T2-weighted magnetic resonance (MR) image (T2WI) for the detection of lumbar transverse process (TP) fractures.@*MATERIALS AND METHODS@#A retrospective review of lumbar spine MR images of 56 patients (mean age = 56.1 years, age range = 17–87 years, male:female = 28:28) was conducted by 2 radiologists. Based on the axial T2WI at the disc level, the paraspinal muscles were classified into 4 compartments and muscle edema (increased signal intensity on axial T2WI) grading performed for each quadrant.@*RESULTS@#A total of 486 TPs (with fracture: 24, without fracture: 462) of 56 patients were evaluated. Muscle edema grade showed moderate correlation with the presence of TP fracture (ρ = 0.466). When the total score of muscle edema was 2.50, the receiver operating characteristic curve showed a sensitivity of 72.7% and a specificity of 90.7%. A higher edema grade had a significantly higher probability of concomitant TP fracture [any sided (total): odds ratio = 1.704 (95% confidence interval = 1.410–2.060)].@*CONCLUSION@#Edema grading of the psoas and paraspinal muscles on axial T2WI of lumbar spine can be helpful in the detection of TP fracture.

Lesions that Mimic Musculoskeletal Infection: A Pictorial Essay

Musculoskeletal (MSK) infections, such as osteomyelitis, infectious arthritis and spondylitis have variable radiographic findings depending on their underlying cause and clinical infection stage. Other disease entities, ranging from simple degenerative lesions to tumorous bone conditions, in which there is no evidence of infectious origin, can share similar radiographic findings. It is important to be aware, when interpreting radiographic features that are typically associated with MSK infections, that a non-infectious MSK disease may be mimicking the radiographic findings of infectious diseases.

An Intraosseous Schwannoma Combined with a Subchondral Fracture of the Femoral Head: a Case Report and Literature Review

Schwannomas are benign nerve sheath tumors that are typically located in soft tissue. Occasionally, schwannomas involve osseous structures. These intraosseous schwannomas are generally benign neoplasms that account for less than 0.2% of primary bone tumors. Schwannomas are very rarely observed in long bones. We present a case of a schwannoma affecting the proximal femur with a coincident subchondral fracture of the femoral head. A 38-year-old-male presented with left hip pain without deteriorating locomotor function. Plain film radiographs displayed a lobulating contoured lesion within the intertrochanteric portion of the femur. The magnetic resonance imaging (MRI) scans showed a tumor occupying the intertrochanteric region. Diffuse bone marrow edema, especially in the subchondral and head portions of the femur that was possibly due to the subchondral insufficiency fracture was also noted. The lesion was surgically excised and bone grafting was performed. Histologically, there was diffuse infiltrative growth of the elongated, wavy, and tapered cells with collagen fibers, which are findings that are characteristic of intraosseous schwannoma. Although very rare, intraosseous schwannoma should be included in the differential diagnosis of radiographically benign-appearing, non-aggressive lesions arising in the femur. The concomitant subchondral fracture of the femoral head confounded the correct diagnosis of intraosseous schwannoma in this case.

Sonographic Findings of Common Musculoskeletal Diseases in Patients with Diabetes Mellitus

Diabetes mellitus (DM) can accompany many musculoskeletal (MSK) diseases. It is difficult to distinguish the DM-related MSK diseases based on clinical symptoms alone. Sonography is frequently used as a first imaging study for these MSK symptoms and is helpful to differentiate the various DM-related MSK diseases. This pictorial essay focuses on sonographic findings of various MSK diseases that can occur in diabetic patients.

Early Bone Marrow Edema Pattern of the Osteoporotic Vertebral Compression Fracture : Can Be Predictor of Vertebral Deformity Types and Prognosis?

OBJECTIVE: To evaluate whether an early bone marrow edema pattern predicts vertebral deformity types and prognosis in osteoporotic vertebral compression fracture (OVCF). METHODS: This retrospective study enrolled 64 patients with 75 acute OVCFs who underwent early MRI and followed up MRI. On early MRI, the low SI pattern of OVCF on T1WI were assessed and classified into 3 types (diffuse, globular or patchy, band-like). On followed up MRI, the vertebral deformity types (anterior wedge, biconcave, crush), degree of vertebral body height loss, incidence of vertebral osteonecrosis and spinal stenosis were assessed for each vertebral fracture types. RESULTS: According to the early bone marrow edema pattern on T1WI, 26 vertebrae were type 1, 14 vertebrae were type 2 and 35 vertebrae were type 3. On followed up MRI, the crush-type vertebral deformity was most frequent among the type 1 OVCFs, the biconcave-type vertebral deformity was most frequent among the type 2 OVCFs and the anterior wedge-type vertebral deformity was most frequent among the type 3 OVCFs (p<0.001). In addition, type 1 early bone marrow edema pattern of OVCF on T1WI were associated with higher incidence of severe degree vertebral body height loss, vertebral osteonecrosis and spinal stenosis on the follow up MRI. CONCLUSION: Early bone marrow edema pattern of OVCF on T1WI, significant correlated with vertebral deformity types on the follow up MRI. The severe degree of vertebral height loss, vertebral osteonecrosis, and spinal stenosis were more frequent in patients with diffuse low SI pattern.

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

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.

Repaired Supraspinatus Tendons in Clinically Improving Patients: Early Postoperative Findings and Interval Changes on MRI

OBJECTIVE: To demonstrate and further determine the incidences of repaired supraspinatus tendons on early postoperative magnetic resonance imaging (MRI) findings in clinically improving patients and to evaluate interval changes on follow-up MRIs. MATERIALS AND METHODS: Fifty patients, who showed symptomatic and functional improvements after supraspinatus tendon repair surgery and who underwent postoperative MRI twice with a time interval, were included. The first and the second postoperative MRIs were obtained a mean of 4.4 and 11.5 months after surgery, respectively. The signal intensity (SI) patterns of the repaired tendon on T2-weighted images from the first MRI were classified into three types of heterogeneous high SI with fluid-like bright high foci (type I), heterogeneous high SI without fluid-like bright high foci (type II), and heterogeneous or homogeneous low SI (type III). Interval changes in the SI pattern, tendon thickness, and rotator cuff interval thickness between the two postoperative MRIs were evaluated. RESULTS: The SI patterns on the first MRI were type I or II in 45 tendons (90%) and type III in five (10%). SI decreased significantly on the second MRI (p < 0.050). The mean thickness of repaired tendons and rotator cuff intervals also decreased significantly (p < 0.050). CONCLUSION: Repaired supraspinatus tendons exhibited high SI in 90% of clinically improving patients on MRI performed during the early postsurgical period. The increased SI and thickness of the repaired tendon decreased on the later MRI, suggesting a gradual healing process rather than a retear.

MR Findings of the Osteofibrous Dysplasia

OBJECTIVE: The aim of this study was to describe MR findings of osteofibrous dysplasia. MATERIALS AND METHODS: MR images of 24 pathologically proven osteofibrous dysplasia cases were retrospectively analyzed for a signal intensity of the lesion, presence of intralesional fat signal, internal hypointense band, multilocular appearance, cortical expansion, intramedullary extension, cystic area, cortical breakage and extraosseous extension, abnormal signal from the adjacent bone marrow and soft tissue and patterns of contrast enhancement. RESULTS: All cases of osteofibrous dysplasia exhibited intermediate signal intensity on T1-weighted images. On T2-weighted images, 20 and 4 cases exhibited heterogeneously intermediate and high signal intensity, respectively. Intralesional fat was identified in 12% of the cases. Internal low-signal bands and multilocular appearance were observed in 91%. Cortical expansion was present in 58%. Intramedullary extension was present in all cases, and an entire intramedullary replacement was observed in 33%. Cortical breakage (n = 3) and extraosseous mass formation (n = 1) were observed in cases with pathologic fractures only. A cystic area was observed in one case. Among 21 cases without a pathologic fracture, abnormal signal intensity in the surrounding bone marrow and adjacent soft tissue was observed in 43% and 48%, respectively. All cases exhibited diffuse contrast enhancement. CONCLUSION: Osteofibrous dysplasia exhibited diverse imaging features ranging from lesions confined to the cortex to more aggressive lesions with complete intramedullary involvement or perilesional marrow edema.

Biceps Femoris Tendon and Lateral Collateral Ligament: Analysis of Insertion Pattern Using MRI

PURPOSE: The biceps femoris tendon (BFT) and lateral collateral ligament (LCL) in the knee were formerly known to form a conjoined tendon at the fibular attachment site. However, the BFT and LCL are attached into the fibular head in various patterns. We classified insertion patterns of the BFT and LCL using MR imaging, and analyzed whether the LCL attaches to the fibular head or not. MATERIALS AND METHODS: A total of 494 consecutive knee MRIs of 470 patients taken between July 2012 and December 2012 were retrospectively reviewed. There were 224 males and 246 females, and patient age varied from 10 to 88 (mean, 48.6). The exclusion criteria were previous surgery and poor image quality. Using 3T fat-suppressed proton density-weighted axial images, the fibular insertion patterns of the BFT and LCL were classified into following types: type I (the LCL passes between the anterior arm and direct arm of the BFT's long head), type II (the LCL joins with anterior arm of the long head of the BFT), type III (the BFT and LCL join to form a conjoined tendon), type IV (the LCL passes laterally around the anterior margin of the BFT), and type V (the LCL passes posteriorly to the direct arm of the BFT's long head). RESULTS: Among the 494 cases of the knee MRI, there were 433 (87.65%) type I cases, 21 (4.25%) type II cases, 2 (0.4%) type III cases, 16 (3.23%) type IV cases, and 22 (4.45%) type V cases. There were 26 cases (5.26%) in which the LCL and BFT were not attached into the fibular head. CONCLUSION: The fibular attachment pattern of the BFT and LCL shows diverse types in MR imaging. The LCL does not adhere to the head in some patients.

Osteochondral Lesion of the Bilateral Femoral Heads in a Young Athletic Patient

Osteochondral lesions of the femoral head are uncommon and few studies have reported their imaging findings. Since joints are at risk of early degeneration after osteochondral damage, timely recognition is important. Osteochondral lesions of femoral head may often be necessary to differentiate from avascular necrosis. Here, we report a case of osteochondral lesions on bilateral femoral heads. This lesion manifested as subchondral cysts in initial radiographs, which led to further evaluation by computed tomography arthrography and magnetic resonance imaging, which revealed overlying cartilage defects.

Sonographic Appearance of Idiopathic Hypertrophy of the First Dorsal Interosseous Muscle of the Hand

We present a rare case of a 28-year-old man with a non-tender soft tissue enlargement on the dorsal side of the first web space of the right hand. Sonographic evaluation showed thickening of the dorsal thenar muscle (dorsal interosseous muscle) without a mass-like or cystic lesion, as compared with the left dorsal thenar muscle. On grasping position, this finding was more prominent and no significantly increased vascular flow was observed in this muscle. We were able to diagnose idiopathic hypertrophy of the first dorsal interosseous muscle solely by sonography. Ultrasonographic evaluation is a noninvasive and accessible tool for diagnosis of pseudotumors, such as idiopathic thenar muscle hypertrophy.

Determination of the Factors Influencing Rupture of Baker's Cysts in the Knee on Plain Radiographs and MRI

PURPOSE: We retrospectively compared plain radiographic and MR imaging findings of acutely ruptured and unruptured Baker's cysts to determine which factors cause rupture of BCs. MATERIALS AND METHODS: The MR findings for 44 Baker's cysts (non-ruptured Baker's cysts in 30 patients and ruptured Baker's cysts in 14 patients) were evaluated. On the MR images, the characteristics of the Baker's cysts, meniscal tears, and the quantity of joint effusions were evaluated. On plain radiographs, the grade of osteoarthritis of the affected knee was evaluated. RESULTS: There was no statistically significant difference with respect to the size of Baker's cysts, meniscal tears, and the grade of osteoarthritis between ruptured and unruptured Baker's cysts. The wall thicknesses, inner signal intensities, inner septations, and the quantity of joint effusions were statistically different between the ruptured and unruptured Baker's cysts. CONCLUSION: The most significant imaging finding which influences the rupture of a Baker's cyst is the quantity of the joint effusion of the affected knee. In management of the patients with Baker's cysts, the quantity of joint effusions should be kept in mind for preventative or treatment trials involving ruptured Baker's cysts.

Follow-Up MR Imaging Assessment of Natural History of Lumbar Disc Herniation in Patients with Recurred Low Back Pain

PURPOSE: To compare lumbar disc changes between initial lumbar spine (L-spine) MRI and follow-up (f/u) MRI that were performed due to recurred backaches. MATERIALS AND METHODS: A total 50 patients who had undergone f/u L-spine MRI were retrospectively reviewed. Five discs (L1-S1) were surveyed in each f/u MRI. Lumbar disc changes were defined as no change, aggravations, or improvements compared to initial disc states. These states were defined on the basis of morphologic status and disc levels. RESULTS: In a total of 250 discs in 50 patients, 31 discs (12.4%) showed morphologic changes of disc lesions, whereas 219 discs (87.6 %) showed no changes. Among the 31 disc lesions, 24 were aggravated and 7 were partially improved. And on the basis of disc status, initially abnormal discs revealed any morphologic changes of the degree of disc herniation. A total of 33.3% of the morphologic changes are noted in initially extruded discs. Fifteen morphologic changes of disc lesions were located at the L4-5 level. CONCLUSION: Our results suggest that correlations between lumbar disc herniations and back pain symptoms are limited, and that evaluations of extra disc lesions are required.

Various Tumor-Mimicking Lesions in the Musculoskeletal System: Causes and Diagnostic Approach

Tumor-mimicking lesions in the musculoskeletal system can be defined as lesions mistaken as tumors due to the presence of palpation upon physical examination or a tumor-like appearance upon radiological examination. Moreover, tumor-mimicking lesions show diverse etiologies and anatomic locations. We illustrated the various tumor-mimicking lesions involving bone and soft tissue. In this review, the tumor-mimicking lesions were classified into those based on clinical examination and those based on radiological examination in musculoskeletal radiology. Awareness of the various causes of tumor-mimicking lesions, correctly obtaining clinical information, and the proper selection of imaging modality are important for the differentiation of tumor-mimicking lesions from true neoplasms.

Soft Tissue Masses in the Extremities: The Accuracy of an Ultrasonographic Diagnosis

PURPOSE: We wanted to retrospectively determine the accuracy of an ultrasonographic diagnosis of superficial soft tissue masses in the extremities by using the histologic results as the reference standard. MATERIALS AND METHODS: From January 2005 to June 2010, 154 patients with soft tissue masses in the extremities and who underwent ultrasonographic evaluation followed by biopsy or resection were retrospectively evaluated. The ultrasonographic and histologic diagnoses of the soft tissue masses were lipoma, ganglion cyst, hemangioma, neurogenic tumor, giant cell tumor of the tendon sheath, epidermoid cyst, fibroma, glomus tumor, Baker's cyst and neurofibromatosis. RESULTS: Out of 154 patients, 114 (74%) patients showed concordance between the histologic diagnosis and the ultrasonographic diagnosis, and the remaining 40 (26%) patients did not. The diagnostic accuracy of each soft tissue mass was 95% for lipoma, 83% for ganglion cyst, 75% for hemangioma, 72% for neurogenic tumor, 50% for giant cell tumor of the tendon sheath, 43% for epidermoid cyst, 33% for fibroma and 100% each for glomus tumor, fibromatosis and Baker's cyst. Aside from these tumors, there were also sarcoma, malignant melanoma, elastofibroma, Kimura disease and pilomatricoma. Among the cases that showed discordance between the histologic diagnosis and the ultrasonographic diagnosis, three of them were notable; pilomatricoma being misdiagnosed as dermatofibroma protuberans, angiolipoma being misdiagnosed as vascular leiomyoma and malignant fibrous histiocytoma being misdiagnosed as a malignant soft tissue mass. CONCLUSION: The accuracy of an ultrasonographic diagnosis for soft tissue masses in the extremities varies greatly according to each type of mass. Lipoma, ganglion cyst, hemangioma, glomus tumor, neurogenic tumor and Baker's cyst showed a relatively high rate of concordance between the ultrasonographic diagnosis and the histologic diagnosis, but epidermoid cyst and fibroma showed a relatively lower rate of concordance.