Faculty Bibliography

Purpose: The aim of this study is to identify markers of early failure of anterior cruciate ligament graft reconstruction (ACLR) based on preoperative MR imaging.
Material(s) and Method(s): We identified 26 patients with early ACLR graft failure (<2 years) who underwent revision between 2011-2015 in a retrospective review of our database. Exclusion criteria included graft choice other than autografts (n=4) and non available preoperative MRI (n=3). Nineteen patients with early ACLR failure were included in the study group. The control group consisted of 38 subjects who underwent ACLR with a minimum of 2 years of clinical follow up and no evidence of graft failure matched by age, sex, BMI and graft type. Preoperative MRI obtained within 8 weeks (range 1-8) following initial trauma were reviewed blinded to the ACLR failure by an experienced (20 years) musculoskeletal radiologist for intra and periarticular lesions including: anterolateral ligament (ALL) injuries (stretch, partial, complete), medial meniscus tear (MM), lateral meniscus tear (LM) tear, posteromedial corner injury (PMC), posterolateral corner injury (PLC) injury, medial collateral ligament tear (MCL), and lateral collateral ligament tear (LCL). Logistic regression analysis was performed.
Result(s): Mean time to ACLR failure was 14 months (range, 1-24 months). Mean follow up of those in the control group was 38 months (range, 2561). Medial meniscus (MM) tear was the best predictor of early ACLR failure (Accuracy=66.7%, p=0.08) followed by the lateral meniscus (p=0.13). MM was a significant predictor of ACLR failure (p=0.02) with odds ratio (OR) 4.2 and 95% confidence interval (CI) [1.19 14.9]. All other variables were not associated with ACLR failure (p>0.20).
Conclusion(s): MM tears were the best predictor of early failure of ACLR. Thus, preserving the integrity of theMMduringACLR procedure may be crucial in minimizing the risk for early ACLR failure

Purpose: To evaluate the prevalence and association of anterolateral ligament (ALL) rupture with other meniscal and ligamentous injuries of the knee in patients with complete acute traumatic anterior cruciate ligament (ACL) tear.
Material(s) and Method(s): Based on retrospective review of our orthopedic surgery database, 57 patients M45:F12, mean age 21 (range:13-34) with acute post traumatic ACL rupture who underwent ACLR seen between 2011 and 2015 were enrolled in this cohort. Preoperative MR examinations was performed by an experienced (20 years) MSK radiologist assessing these variables: anterolateral ligament (ALL) rupture, MM tear, LM tear tear, posteromedial corner injury (PMC), posterolateral corner injury (PLC) injury, MCL tear, and lateral collateral ligament tear (LCL). Odds ratios and their 95% confidence interval were used to assess the associations of ALL with other injuries in the knee. To rule out confounding factors we used the Cochran Mantel Haenszel method in an analysis stratified by gender and BMI (normal, overweight).
Result(s): Most commonly reported lesions were of the MM 63%, and PLC 64%. ALL partial or complete tears and Segond avulsion fracture were reported in 28 patients (49%). Anterolateral lesions were associated with a 10 fold decreased risk of MM tear (odds ratio [OR] = 0.10, 95% [CI]=[0.028, 0.38]) and a 4.6 fold increased risk of LCL tear (OR=4.68, 95% CI=[1.28 17.1]). Neither gender nor BMI were confounding for the associations of ALL with MM and LCL tears. No other statistically significant associations betweenALL rupture and LM, PMC, PLC and MCL injury were found.
Conclusion(s): Failure of the ALL during acute traumatic ACL rupture is often associated with tear of the LCL. This may have a protective effect over theMMdue to potential 'capsular release' ewith increased mobility of the MM and decreased risk of clipping/tearing between the approximating medial compartment surfaces during pivot shift trauma

Purpose: Study the diagnostic accuracy of the 'smoke sign' on routine shoulder MR examinations for detection of pectoralis tendon humeral insertional injury.
Material(s) and Method(s): IRB approved, HIPAA compliant study. Radiology database queried for MR with reports containing 'pectoralis' and 'shoulder' from 9/2012 to 7/2018. Patients without prior pectoralis surgery with shoulder and pectoralis MR within 4 months, and shoulder MRpositive for pectoralis injury based on report and imaging review that clearly depicted pectoralis injury were included. Anonymized, randomized shoulder MR reviewed independently by two musculoskeletal fellowship-trained radiologists for 'smoke sign' on coronal- and sagittal-oblique sequences. Teaching session provided guidelines for smoke sign (ill-defined edema lateral or anterior to short head biceps/ coracobrachialis on coronal- and sagittal-oblique fluid-sensitive images, respectively) before reader review. AllMR reviewed by senior author for presence and location of pectoralis injury.
Result(s): 52 shoulder MR exams total: 33 patients with shoulder and pectoralis MR, 4 patients with shoulder MR and pectoralis imaging on same exam, 15 patients with shoulder MR only.14/52 exams didn't have pectoralis injury on shoulder or pectoralis MR; 'smoke sign' was present in none of these cases. Remaining 38 patients had pectoralis injuries; 24/38 (humeral avulsion), 4/38 (tendon tear) 8/38 (myotendinous junction), 2/38 (intramuscular injury). Pooled sensitivity, specificity, negative and positive predictive value for 'smoke sign' was 86%, 100%, 76% and 100%. When only tendon tears and avulsions were assessed, this rose to 100%, 100%, 100% and 100%. Kappa coefficient was 0.922 for the presence of the sign on coronal oblique 0.876 on sagittal oblique images. Smoke sign was present in all 8 surgically proven pectoralis injuries.
Conclusion(s): 'Smoke sign' is sensitive and specific for pectoralis humeral insertional injury, especially tendon tears and avulsions. Detection of this sign on routine shoulder MR should prompt careful evaluation of the distal pectoralis tendon and recommendation for dedicated pectoralis imaging

Evaluation of traumatic peripheral nerve injuries has classically been based on clinical and electrophysiologic criteria. US and MRI have been widely used for morphologic assessment of nerve injury sites and concomitant lesions. In the past few years, morphologic MR neurography has significantly increased its clinical applications on the basis of three-dimensional or two-dimensional images with and without fat-suppression techniques. However, these sequences have a major drawback: absence of pathophysiologic information about functional integrity or axonal flow of peripheral nerves. In this scenario, functional MRI techniques such as diffusion-weighted imaging (DWI) or diffusion tensor imaging (DTI) can be used as a complementary tool in initial evaluation of peripheral nerve trauma or in assessment of trauma undergoing surgical repair. These approaches provide not only morphologic but also functional information about extent and degree of nerve impairment. Functional MR neurography can also be applied to selection, planning, and monitoring of surgical procedures that can be performed after traumatic peripheral nerve injuries, such as neurorrhaphy, nerve graft, or neurolysis, as it provides surgeons with valuable information about the functional status of the nerves involved and axonal flow integrity. The physical basis of DWI and DTI and the technical adjustments required for their appropriate performance for peripheral nerve evaluation are reviewed. Also, the clinical value of DWI and DTI in assessment of peripheral nerve trauma is discussed, enhancing their potential impact on selection, planning, and monitoring of surgical procedures employed for peripheral nerve repair. Online supplemental material is available for this article. ^©RSNA, 2019.

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

INTRODUCTION/BACKGROUND: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/CONCLUSIONS: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/CONCLUSIONS:• 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.

Entrapment neuropathies of the lower extremity are commonly encountered and present a diagnostic challenge. Historical diagnostic workhorses-the physical examination combined with electrodiagnostic studies-are now frequently supplemented by MR neurography. MR neurography is a high-resolution, noninvasive, and operator-independent imaging modality that has proven useful in diagnosis, disease severity assessment, and informing treatment decisions in the management of lower extremity entrapment neuropathies. Currently, the assessment of the peripheral nerves relies heavily on reader identification of morphologic nerve changes; however, emerging innovative MR sequences and PET/MR imaging hold the potential to provide noninvasive means of functional assessment.

Shoulder pain is one of the most common reasons for musculoskeletal-related physician visits. Imaging plays an important role in identifying the specific cause of atraumatic shoulder pain. This review is divided into two parts. The first part provides a general discussion of various imaging modalities (radiographs, arthrography, nuclear medicine, ultrasound, CT, and MRI) and their usefulness in evaluating atraumatic shoulder pain. The second part focuses on the most appropriate imaging algorithms for specific shoulder conditions including: rotator cuff disorders, labral tear/instability, bursitis, adhesive capsulitis, biceps tendon abnormalities, postoperative rotator cuff tears, and neurogenic pain. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

OBJECTIVES/OBJECTIVE: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/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: = 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/CONCLUSIONS: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.

OBJECTIVE:Postoperative imaging after surgery for anterior glenohumeral instability poses a great challenge, which can be compounded by a lack of familiarity with the many different operative techniques and their expected normal appearances and complications. In this article, we discuss the postoperative imaging appearances of anterior glenohumeral instability surgery with a review of currently recommended treatment guidelines. CONCLUSION/CONCLUSIONS:It is important for radiologists to accurately detect complications of anterior shoulder instability surgery at postoperative imaging.