Correction to: MRI assessment of the thigh musculature in dermatomyositis and healthy subjects using diffusion tensor imaging, intravoxel incoherent motion and dynamic DTI.

The original version of this article, published on 04 June 2018, unfortunately contained a mistake.

MRI assessment of the thigh musculature in dermatomyositis and healthy subjects using diffusion tensor imaging, intravoxel incoherent motion and dynamic DTI.

INTRODUCTION: Dermatomyositis (DM) is an idiopathic inflammatory myopathy involving severe debilitation in need of diagnostics. We evaluated the proximal lower extremity musculature with diffusion tensor imaging (DTI), intravoxel incoherent motion (IVIM) and dynamic DTI in DM patients and controls and compared with standard clinical workup. METHODS: In this IRB-approved, HIPAA-compliant study with written informed consent, anatomical, Dixon fat/water and diffusion imaging were collected in bilateral thigh MRI of 22 controls and 27 DM patients in a 3T scanner. Compartments were scored on T1/T2 scales. Single voxel dynamic DTI metrics in quadriceps before and after 3-min leg exercise were measured. Spearman rank correlation and mixed model analysis of variance/covariance (ANOVA/ANCOVA) were used to correlate with T1 and T2 scores and to compare patients with controls. RESULTS: DM patients showed significantly lower pseudo-diffusion and volume in quadriceps than controls. All subjects showed significant correlation between T1 score and signal-weighted fat fraction; tissue diffusion and pseudo-diffusion varied significantly with T1 and T2 score in patients. Radial and mean diffusion exercise response in patients was significantly higher than controls. CONCLUSION: Static and dynamic diffusion imaging metrics show correlation with conventional imaging scores, reveal spatial heterogeneity, and provide means to differentiate dermatomyositis patients from controls. KEY POINTS: • Diffusion imaging shows regional differences between thigh muscles of dermatomyositis patients and controls. • Signal-weighted fat fraction and diffusion metrics correlate with T1/T2 scores of disease severity. • Dermatomyositis patients show significantly higher radial diffusion exercise response than controls.

Spatially resolved kinetics of skeletal muscle exercise response and recovery with multiple echo diffusion tensor imaging (MEDITI): a feasibility study.

OBJECTIVES: We describe measurement of skeletal muscle kinetics with multiple echo diffusion tensor imaging (MEDITI). This approach allows characterization of the microstructural dynamics in healthy and pathologic muscle. MATERIALS AND METHODS: In a Siemens 3-T Skyra scanner, MEDITI was used to collect dynamic DTI with a combination of rapid diffusion encoding, radial imaging, and compressed sensing reconstruction in a multi-compartment agarose gel rotation phantom and within in vivo calf muscle. An MR-compatible ergometer (Ergospect Trispect) was employed to enable in-scanner plantar flexion exercise. In a HIPAA-compliant study with written informed consent, post-exercise recovery of DTI metrics was quantified in eight volunteers. Exercise response of DTI metrics was compared with that of T2-weighted imaging and characterized by a gamma variate model. RESULTS: Phantom results show quantification of diffusivities in each compartment over its full dynamic rotation. In vivo calf imaging results indicate larger radial than axial exercise response and recovery in the plantar flexion-challenged gastrocnemius medialis (fractional response: nT2w = 0.385 ± 0.244, nMD = 0.163 ± 0.130, nλ1 = 0.110 ± 0.093, nλrad = 0.303 ± 0.185). Diffusion and T2-weighted response magnitudes were correlated (e.g., r = 0.792, p = 0.019 for nMD vs. nT2w). CONCLUSION: We have demonstrated the feasibility of MEDITI for capturing spatially resolved diffusion tensor data in dynamic systems including post-exercise skeletal muscle recovery following in-scanner plantar flexion.

Normal variants and pitfalls in MR imaging of the ankle and foot.

Normal anatomic variants may erroneously be interpreted as pathologic conditions on MR imaging of the ankle and foot. Therefore, sufficient knowledge of the normal anatomy and its variations is crucial for accurate diagnostic analysis of such images. This article will focus on outlining variants and MR imaging interpretation pitfalls of the tendons, ligaments, muscles, bones, and other miscellaneous structures of the foot and ankle.

MR imaging of tendon abnormalities of the foot and ankle.

MR imaging, with its unique soft-tissue contrast resolution, noninvasiveness, and multiplanar capabilities, has been applied to the assessment of tendon abnormalities of the foot and the ankle.

MR imaging features of diseases of the peroneal tendons.

Injuries of the peroneal tendons including peritendinosis/tenosynovitis, tendinosis, rupture, dislocation are being detected with greater frequency since the advent of MR imaging. This article focuses on the normal as well as pathologic MR features of the peroneal tendons.

MR imaging and CT in the assessment of osseous abnormalities of the ankle and foot.

This article focuses on the contributions of MR imaging and CT toward the evaluation of painful osseous abnormalities of the foot and ankle. Inconclusive findings on conventional radiographs often mandate further work up with the more advanced cross-sectional imaging techniques. Often, however, the radiologist remains unsure, which modality, CT or MR imaging, should be used. Based on our experience, CT and MR imaging play a complementary role in the assessment of these disorders.

Tethered cord in a patient with multiple vertebral segmentation defects: a case report.

Short trunk dwarfism with multiple vertebral segmentation defects (MVSD) represents a heterogeneous group of disorders characterized by the presence of multiple vertebral and rib abnormalities. A two and one-half year-old female with the spondylothoracic dysostosisform of MVSD is presented. In addition to skeletal anomalies, a lumbar hemangioma, bilateral foot deformities, distal leg atrophy and weakness, and areflexia at the ankles were present. An underlying neuropathic process was suspected. Results of urodynamic studies were suggestive of a neurogenic bladder. Magnetic resonance imaging of the spine demonstrated a tethered spinal cord. Although various brain and spinal cord anomalies have been described in MVSD, this is the first reported case, to our knowledge, of a tethered spinal cord in a patient with MVSD. We recommend that the management of patients with MVSD include comprehensive neurological evaluation and monitoring with appropriate electrodiagnostic, urodynamic, and neuroimaging studies.

Traumatic musculotendinous injuries of the knee: diagnosis with MR imaging.

Magnetic resonance (MR) imaging is the imaging modality of choice for evaluation of acute traumatic musculotendinous injuries of the knee. Three discrete categories of acute injuries to the musculotendinous unit can be defined: muscle contusion, myotendinous strain, and tendon avulsion. Among the quadriceps muscles, the rectus femoris is the most susceptible to injury at the myotendinous junction due to its superficial location, predominance of type II fibers, eccentric muscle action, and extension across two joints. Among the muscles of the pes anserinus, the sartorius is the most susceptible to strain injury due to its superficial location and biarticular course. The classic fusiform configuration of the semimembranosus along with a propensity for eccentric actions also make it prone to strain injury. MR imaging findings associated with rupture of the iliotibial tract include discontinuity and edema, which are best noted on coronal images. The same mechanism of injury that tears the arcuate ligament from its fibular insertion can also result in avulsion injury of the biceps femoris. The gastrocnemius muscle is prone to strain injury due to its action across two joints and its superficial location. Injuries of the muscle belly and myotendinous junction of the popliteus are far more common than tendinous injuries.

From the RSNA Refresher Courses. Radiological Society of North America. MR imaging of the ankle and foot.

Magnetic resonance (MR) imaging has opened new horizons in the diagnosis and treatment of many musculoskeletal diseases of the ankle and foot. It demonstrates abnormalities in the bones and soft tissues before they become evident at other imaging modalities. The exquisite soft-tissue contrast resolution, noninvasive nature, and multiplanar capabilities of MR imaging make it especially valuable for the detection and assessment of a variety of soft-tissue disorders of the ligaments (eg, sprain), tendons (tendinosis, peritendinosis, tenosynovitis, entrapment, rupture, dislocation), and other soft-tissue structures (eg, anterolateral impingement syndrome, sinus tarsi syndrome, compressive neuropathies [eg, tarsal tunnel syndrome, Morton neuroma], synovial disorders). MR imaging has also been shown to be highly sensitive in the detection and staging of a number of musculoskeletal infections including cellulitis, soft-tissue abscesses, and osteomyelitis. In addition, MR imaging is excellent for the early detection and assessment of a number of osseous abnormalities such as bone contusions, stress and insufficiency fractures, osteochondral fractures, osteonecrosis, and transient bone marrow edema. MR imaging is increasingly being recognized as the modality of choice for assessment of pathologic conditions of the ankle and foot.

Morton's neuroma: is it always symptomatic?

OBJECTIVE: We determined the prevalence of clinically silent Morton's neuroma and searched for distinguishing MR imaging features of Morton's neuroma in patients with clinical complaints related to this entity and in patients with clinically silent lesions. MATERIALS AND METHODS: One radiologist who was unaware of clinical findings retrospectively reviewed 85 consecutive foot MR examinations. MR imaging criteria for Morton's neuroma included a low- to intermediate-signal-intensity soft-tissue mass in the intermetatarsal space. The size, location, and signal intensity of each neuroma and the presence of intermetatarsal bursae were recorded. The patients were subdivided into symptomatic or asymptomatic groups on the basis of the patients' answers on a questionnaire documenting the locations and characteristics of symptoms and discussions with each referring physician about clinical findings. Surgical confirmation was available in eight of 25 symptomatic patients. RESULTS: The prevalence of Morton's neuroma in patients with no clinical evidence of this condition was 33% (19/57). Twenty-five patients had symptomatic Morton's neuroma, 19 had Morton's neuroma based on MR imaging findings with no clinical manifestations, and 41 did not have Morton's neuroma. Slightly larger lesions were observed in the symptomatic group, although significant overlap was noted between the two groups. The mean transverse diameter of symptomatic neuromas was 5.3 mm (standard deviation, 2.14) compared with 4.1 mm (standard deviation, 1.75) for asymptomatic neuromas; this difference was marginally significant (p = 0.05). CONCLUSION: The MR imaging diagnosis of Morton's neuroma does not imply symptomatology. Careful correlation between clinical and MR imaging findings is mandatory before Morton's neuroma is considered clinically relevant.

Superior labrum anterior-posterior lesions: diagnosis with MR arthrography of the shoulder.

PURPOSE: To determine the accuracy of magnetic resonance (MR) arthrography in the diagnosis of superior labrum anterior-posterior (SLAP) lesions of the shoulder. MATERIALS AND METHODS: From January 1995 to June 1998, MR arthrography of the shoulder was performed in 159 patients with a history of chronic shoulder pain or instability. Fifty-two patients underwent arthroscopy or open surgery 12 days to 5 months after MR arthrography. Diagnostic criteria for SLAP lesion included marked fraying of the articular aspect of the labrum, biceps anchor avulsion, inferiorly displaced bucket handle fragment, and extension of the tear into the biceps tendon fibers. Surgical findings were correlated with those from MR arthrography. RESULTS: SLAP injuries were diagnosed at surgery in 19 of the 52 patients (37%). Six of the 19 lesions (32%) were classified as type I, nine (47%) as type II, one (5%) as type III, and three (16%) as type IV. MR arthrography had a sensitivity of 89% (17 of 19 patients), a specificity of 91% (30 of 33 patients), and an accuracy of 90% (47 of 52 patients). The MR arthrographic classification showed correlation with the arthroscopic or surgical classification in 13 of 17 patients (76%) in whom SLAP lesions were diagnosed at MR arthrography. CONCLUSION: MR arthrography is a useful and accurate technique in the diagnosis of SLAP lesions of the shoulder. MR arthrography provides pertinent preoperative information with regard to the exact location of tears and grade of involvement of the biceps tendon.

Glenohumeral instability: evaluation using MR arthrography of the shoulder.

In the setting of glenohumeral instability or when internal derangement of the shoulder joint is suspected, MR arthrography has been demonstrated to be an accurate diagnostic imaging technique. Knowledge of the complex anatomy of the shoulder and its variations is essential in order to maximize diagnostic accuracy.

MR imaging in sports injuries of the foot and ankle.

MR imaging has become the diagnostic modality of choice for the evaluation of traumatic ligamentous and tendinous injures of the foot and ankle, occult bony trauma, and osteochondral lesions of the talus. This article reviews the current applications of MR imaging for the evaluation of sports-related injuries of the foot and ankle, including fractures, sprains, tendon injuries, and heel pain.

Normal variants and pitfalls in magnetic resonance imaging of the ankle and foot.

Distinction of normal from disease is one of the principal tenets in magnetic resonance imaging (MRI) interpretation of the foot and ankle. Therefore, familiarity with normal anatomic variants and pitfalls in the foot and ankle is crucial for accurate diagnostic analysis of MR images. This article will focus on outlining variants and MRI interpretation pitfalls of the tendons, muscles, bones, ligaments, and other miscellaneous structures of the foot and ankle.

Chondrocalcinosis of the hyaline cartilage of the knee: MRI manifestations.

PURPOSE: To determine the ability of MRI to detect the presence of crystals of calcium pyrophosphate in the articular cartilage of the knee. DESIGN AND PATIENTS: The MR studies of 12 knees (11 cases) were reviewed retrospectively and correlated with radiographs (12 cases) and the findings at arthroscopy (2 cases) and surgery (1 case). A total of 72 articular surfaces were evaluated. Radiographic, surgical or arthroscopic demonstration of chondrocalcinosis was used as the gold standard. Additionally, two fragments of the knee of a patient who underwent total knee replacement and demonstrated extensive chondrocalcinosis were studied with radiography and MRI using spin-echo T1-, T2- and proton-density-weighted images as well as two- and three-dimensional fat saturation (2D and 3D Fat Sat) gradient recalled echo (GRE) and STIR sequences. RESULTS: MRI revealed multiple hypointense foci within the articular cartilage in 34 articular surfaces, better shown on 2D and 3D GRE sequences. Radiographs showed 12 articular surfaces with chondrocalcinosis. In three cases with arthroscopic or surgical correlation, MRI demonstrated more diffuse involvement of the articular cartilage than did the radiographs. The 3D Fat Sat GRE sequences were the best for demonstrating articular calcification in vitro. In no case was meniscal calcification identified with MRI. Hyperintense halos around some of the calcifications were seen on the MR images. CONCLUSION: MRI can depict articular cartilage calcification as hypointense foci using GRE techniques. Differential diagnosis includes loose bodies, post-surgical changes, marginal osteophytes and hemosiderin deposition.

MR arthrography of the shoulder: variants and pitfalls.

Use of magnetic resonance arthrography to evaluate pathologic conditions of the shoulder is becoming widespread. However, normal anatomy or anatomic variations can cause interpretive errors. The most common variations occur at the origins of the glenohumeral ligaments (GHLs) and the insertion of the joint capsule. Among the GHL variants, common origin of the superior and middle ligaments is the most frequent followed by thinning, thickening, or absence of a ligament, most often the middle one. Absence or thinning of one ligament is sometimes associated with thickening of another or changes in the size and shape of the anterior capsular recesses. Common normal variants of the labrum include foramen sublabrum (detachment of the anterosuperior labrum from the glenoid margin) and the Buford complex (absence of the anterosuperior labrum in association with a thick middle GHL). Pitfalls related to the arthrographic technique include (a) visualization of a deep sulcus between the insertion of the long head of the biceps tendon and the superior labrum and (b) an apparent type III capsular insertion due to overdistention of the capsule by injected contrast material.

MR imaging of dislocation of the posterior tibial tendon.

OBJECTIVE: The purpose of this article is to describe the MR imaging appearance of seven cases of posterior tibial tendon dislocation and subluxation. CONCLUSION: Posterior tibial tendon dislocation is a rare but important entity usually related to a previous traumatic event. The clinical diagnosis is often missed because of its rarity. MR imaging provides important clues to the diagnosis and preoperative evaluation of this condition.

MR imaging of normal variants and interpretation pitfalls of the elbow.

Discrimination of normal anatomic landmarks from true disease is one of the fundamental tenets of adept MR imaging. The radiologist is thus compelled to accumulate a comprehensive knowledge of normal structures, variants, and potential MR imaging interpretation pitfalls. In this article the authors focus on a number of normal, bony, ligamentous, and tendinous structures that can simulate disease at the elbow. A discussion of the particular anatomy responsible for the appearance of each of these interpretation pitfalls is provided. In addition, ways to distinguish these pitfalls from true elbow disease are discussed.

MR features of nerve disorders at the elbow.

MR imaging is a useful method for evaluating nerve disease. It can portray the normal anatomy and identify unsuspected space-occupying masses. Severe intrinsic nerve disease can be depicted. This article outlines the normal anatomy of the three major nerves that traverse the elbow joint: the ulnar nerve, the median nerve, and the radial nerve. Entrapment and compression neuropathies of each nerve are discussed in detail. Finally, the role of MR imaging in delineating each nerve abnormality is examined.