Mohammad Samim

MRI of anterior knee pain

Anterior knee pain is the most common knee complaint. It may be due to a variety of soft tissue or osseous abnormalities. Knowledge of the radiologic appearance of the abnormalities allows more accurate diagnosis of the cause of the pain including chondral abnormalities, patellar instability and dislocation, femoral trochlear dysplasia, abnormal patellar location, bipartite patella, various tendinopathies, bursal inflammation, traction apophysitis in pediatric and adolescent patients, and miscellaneous diseases including mediopatellar plica syndrome and Hoffa’s disease. Radiographs are often obtained to exclude acute osseous abnormalities, such as fractures. Magnetic resonance (MR) imaging offers superior soft tissue contrast resolution and allows for more accurate evaluation of the underlying etiology and therefore may improve treatment and possible surgical planning.

Arterial pseudoaneurysms of the shoulder mimicking other entities: utilization of pulsation artifact on musculoskeletal MR for accurate diagnosis in 2 cases

We present two cases of pseudoaneurysm (PSA) about the shoulder mimicking more common clinical entities—soft tissue neoplasm and septic arthritis—for which biopsy of the mass and joint aspiration were requested respectively. We review the imaging findings of PSA with emphasis on findings in musculoskeletal protocol MRI, including the identification of pulsation artifact in both cases, which was critical to establishing the correct diagnosis. In the proper clinical setting, with imaging findings demonstrating a complex mass or fluid collection, MR images should be scrutinized for the presence of pulsation artifact, which can help diagnose a high-flow vascular lesion and avoid a potentially harmful invasive procedure such as biopsy.

Semimembranosus muscle herniation: a rare case with emphasis on muscle biomechanics

Muscle herniations are rare and most reported cases involve muscles of the lower leg. We use a case of muscle herniation involving the semimembranosus muscle, presenting as a painful mass in an adolescent male after an unspecified American football injury, to highlight a simple concept of muscle biomechanics as it pertains to muscle hernia(s): decreased traction upon muscle fibers can increase conspicuity of muscle herniation(s)—this allows a better understanding of the apt provocative maneuvers to employ, during dynamic ultrasound or magnetic resonance imaging, in order to maximize diagnostic yield and, thereby, limit patient morbidity related to any muscle herniation. Our patient subsequently underwent successful decompressive fasciotomy and has since returned to his normal daily activities.

Imaging of Mueller-Weiss Syndrome: A Review of Clinical Presentations and Imaging Spectrum

OBJECTIVE Mueller-Weiss syndrome is a complex condition of the adult tarsal navicular characterized by progressive fragmentation leading to mid- and hindfoot pain and deformity. Since its first descriptions in the early 20th century, controversy has persisted regarding its pathogenesis. CONCLUSION This article reviews the literature and discusses the anatomy, epidemiology, causes, clinical and radiologic findings, and treatment of Mueller-Weiss syndrome, and thus permits a better understanding of this disease and its management.

3D-MRI versus 3D-CT in the evaluation of osseous anatomy in femoroacetabular impingement using Dixon 3D FLASH sequence

ObjectiveTo determine if hip 3D-MR imaging can be used to accurately demonstrate femoral and acetabular morphology in the evaluation of patients with femoroacetabular impingement.Materials and methodsWe performed a retrospective review at our institution of 17 consecutive patients (19 hips) with suspected femoroacetabular impingement who had both 3D-CT and 3D-MRI performed of the same hip. Two fellowship-trained musculoskeletal radiologists reviewed the imaging for the presence and location of cam deformity, anterior–inferior iliac spine variant, lateral center-edge angle, and neck–shaft angle. Findings on 3D-CT were considered the reference standard. The amount of radiation that was spared following introduction of 3D-MRI was also assessed.ResultsAll 17 patients suspected of FAI had evidence for cam deformity on 3D-CT. There was 100% agreement for diagnosis (19 out of 19) and location (19 out of 19) of cam deformity when comparing 3D-MRI with 3D-CT. There were 3 type I and 16 type II anterior–inferior iliac spine variants on 3D-CT imaging with 89.5% (17 out of 19) agreement for the anterior–inferior iliac spine characterization between 3D-MRI and 3D-CT. There was 64.7% agreement when comparing the neck–shaft angle (11 out of 17) and LCEA (11 out of 17) measurements. The use of 3D-MRI spared each patient an average radiation effective dose of 3.09 mSV for a total reduction of 479 mSV over a 4-year period.Conclusion3D-MR imaging can be used to accurately diagnose and quantify the typical osseous pathological condition in femoroacetabular impingement and has the potential to eliminate the need for 3D-CT imaging and its associated radiation exposure, and the cost for this predominantly young group of patients.

Abnormal alignment of the left lower extremity and irregular gait

Focal fibrocartilaginous dysplasia (FFCD) is a rare benign entity first described by Bell in 1985 [1]. The most common site of FFCD is the proximal tibia followed by distal femur, forearm, humerus, phalanx, and vertebra transverse process [2, 3]. FFCD is most commonly noticed when children start crawling and ambulating [4]. Usual presentation is unilateral tibia vara, limb shortening, and tibial torsion [4]. Etiology of FFCD is not completely known. It is believed to be a failure of differentiation of a mesenchymal anlage, resulting in excessive fibrocartilage formation and interfering with growth of the medial tibial metadiaphysis and natural slipping of the periosteum for growth [1, 3]. In proximal tibia, this lesion typically occurs in the region of pes anserine tendons insertion [5]. Prior insult to the medial tibia has been postulated as an etiology [4, 5]. The characteristic radiographic findings are tibia vara associated with an elliptical lucency within the medial tibial metadiaphyseal cortex with surrounding sclerotic bone and absence of cortical margin at the superomedial aspect of the lesion [6]. The cortical thickening is more pronounced along the lateral margin of the lesion [7]. On CT, the corresponding lucency contains the insertion of the pes anserine tendons. MRI demonstrates characteristic low-signal T1 and T2 intraosseous soft tissue component corresponding to the cortical lucency, surrounded by hypointense sclerotic bone [2]. The signal intensity of the soft tissue component is hypointense to the hyaline cartilage, similar to fibrocartilage. Post-contrast images as in our case typically do not display significant enhancement [7]. FFCD is typically a radiographic diagnosis and CT and MRI should be reserved for problem solving and/or operative planning. Recognition of this entity on radiographs could have prevented our case from undergoing further imaging. Correct diagnosis of FFCD is crucial to avoid unnecessary invasive procedures. Differential diagnosis for tibia vara in children includes infantile Blount’s disease, rickets, and asymmetric closure of the epiphysis secondary to infection or trauma [3]. Blount’s disease typically involves the epiphysis and metaphysis and can present bilaterally as opposed to FFCD, which is typically unilateral without direct involvement of the growth plate [4]. Rickets usually involves more than one bone and is accompanied by classic metaphyseal flaring and growth plate widening and can present at the age of 2 in severe cases [8]. Osteoid osteoma in the medial tibia can potentially cause tibia vara. Osteoid osteoma has a lucent nidus, which can be centrally mineralized, and is usually surrounded by reactive sclerotic bone and is seen in a wide age range [9]. On certain imaging slices, FFCD can mimic the appearance of nonmineralized osteoid osteoma nidus, while superomedial cortical bone defect in FFCD can differentiate the diagnosis. Due to the classic imaging findings, biopsy is generally not recommended. For cases that have undergone biopsy, pathology demonstrated dense hypocellular fibrous tissue interspersed with foci resembling fibrocartilage [1]. The presence of fibrocartilage is not essential for diagnosis [6]. Approximately 45% of the cases of tibial FFCD have spontaneously resolved over the span of approximately 57 months, which may be an underestimation of cases that could potentially spontaneously regress if intervention had not been performed [6]. Conservative management has been recommended if the Levin–Drennan angle, measured by the intersection The case presentation can be found at https://doi.org/10.1007/s00256018-2912-x

Coracoid graft union: a quantitative assessment by computed tomography in primary and revision Latarjet procedure

BACKGROUND The goal of the Latarjet procedure is restoration of shoulder stability enabled by accurate graft positioning and union. This study aimed to establish a reproducible method of quantitatively assessing coracoid graft osseous union percentage (OUP) using computed tomography (CT) scans and to determine the effect of other factors on the OUP. MATERIALS AND METHODS Postoperative CT scans of 41 consecutive patients treated with the open Latarjet procedure (37% primary, 63% revision) for anterior glenohumeral instability were analyzed for the OUP, position of the graft, and screw type and angle. Two musculoskeletal radiologists independently examined the images 2 times, and intraobserver and interobserver reliability was calculated using intraclass correlation coefficient (ICC). RESULTS Mean OUP was 66% (range, 0%-94%) using quantitate methods, with good intraobserver reliability (ICC = 0.795) and interobserver reliability (ICC = 0.797). Nonunion and significant graft resorption was found in 2 patients. No significant difference was found in the mean OUP in the primary (63%) vs. revision Latarjet procedure (67%). Grafts were flush in 39%, medial in 36%, and lateral in 8%. The medial and neutral graft position was associated with slightly higher OUP (72% and 69%) compared with lateral (65%). OUP was higher when the superior screw angle was less than 17° and the inferior screw angle was less than 24°. This difference did not reach statistical significance. Screw type was not associated with significant difference in OUP. CONCLUSION Quantitative assessment of osseous union of the graft using a reproducible method that we introduced showed similar OUP in the primary and revision Latarjet procedure.

Hip arthroscopy-MRI correlation and differences for hip anatomy and pathology: What radiologists need to know

Hip MRI and arthroscopy have important roles for the evaluation of the patient with hip pain. An understanding of what orthopedic surgeons want to know before and after hip arthroscopy as well as the limitations of arthroscopy would enable radiologists to improve their imaging interpretations and produce more clinically relevant, management guiding reports. The goal of this article is to review the basic principles of hip arthroscopy and MRI and compare their strengths and weaknesses. Normal clinically relevant hip anatomy, important pathologic conditions such as labral tears and cartilage injuries, femoroacetabular impingement specific findings like cam and pincer morphology, extra-articular conditions such as abductor and iliopsoas tendons pathology and common post-operative appearances are reviewed on MRI and arthroscopy.

Does the Addition of DWI to Fluid-Sensitive Conventional MRI of the Sacroiliac Joints Improve the Diagnosis of Sacroiliitis?

OBJECTIVE The purpose of this study was to determine whether adding DWI to conventional MRI of the sacroiliac joints improves the diagnostic performance of MRI readers in the detection of sacroiliitis. MATERIALS AND METHODS MR images of the sacroiliac joints of 63 patients with lower back pain obtained between January 2016 and December 2016 were analyzed retrospectively. Three readers reviewed the MRI studies for bone marrow edema lesions around the sacroiliac joints as a marker of active sacroiliitis and gave a diagnostic confidence score of 0-4 using MRI without DWI and MRI with DWI in separate sessions. The normalized apparent diffusion coefficient mean (nADCmean) was measured. Clinical and radiologic data using the Assessment of Spondyloarthritis International Society criteria were the reference for the diagnosis of sacroiliitis. Diagnostic performance, confidence scores, and interreader agreement for the MRI methods were compared. The nADCmean values of patients with and those without sacroiliitis were compared. RESULTS The accuracy, sensitivity, and specificity of MRI without DWI were 68.3%, 69.0%, and 67.6% and for MRI with DWI were 74.6%, 69.0%, and 79.4% (accuracy and sensitivity, p > 0.100; specificity, p = 0.039). The mean confidence score for MRI without DWI was 3.60 and for MRI with DWI was 3.67 (p = 0.270). The kappa coefficient for MRI without DWI was 0.28 and for MRI with DWI was 0.46 (p = 0.041). The nADCmean in patients with sacroiliitis was 3.86 and in patients without sacroiliitis was 1.6 (p ≤ 0.001). The nADCmean AUC was 0.758 (95% CI, 0.67-0.83). CONCLUSION The addition of DWI to conventional MRI does not significantly improve overall diagnostic performance in terms of accuracy, sensitivity, or confidence in the detection of inflammatory sacroiliitis, but it does have increased specificity and interobserver agreement. ADC threshold values can be used as predictors of sacroiliitis but give no added advantage over MRI with DWI.

Postoperative MRI of Massive Rotator Cuff Tears

OBJECTIVE The aim of this article is to review the postoperative MRI appearances of irreparable massive rotator cuff tears (RCTs) after surgery was performed using newer techniques, including patch repair, muscle tendon transfer, superior capsular reconstruction, and subacromial balloon implantation. CONCLUSION Newer surgical techniques are emerging for the management of massive RCTs. As radiologists become increasingly likely to encounter postoperative imaging studies of RCTs repaired using these techniques, familiarity with the normal postoperative appearances and complications associated with these techniques becomes important.