Challenges in the Interpretation of MRI Examinations Without Radiographic Correlation: Pearls and Pitfalls to Avoid.

As physics introduces more complex and seemingly thorough techniques to evaluate patient symptoms, cross-sectional imaging, especially magnetic resonance imaging (MRI), seems like the modality of choice to best help patients. However, musculoskeletal radiology (MSK) requires not just the excellent soft-tissue contrast provided by MRI but also an evaluation of the aggressiveness of a lesion, a detailed evaluation of osseous anatomy or distribution of disease, and a way to easily identify calcifications and gas in soft tissue in order to make the correct diagnosis. This article will demonstrate, through numerous cases, the importance of radiographs in the full characterization of MSK-related pathology. It will focus on imaging pearls and pitfalls to avoid when radiographs are not available and discuss the findings that can be expected if comparison radiographs were available.

Traumatic knee injury: correlation of radiographic effusion size with the presence of internal derangement on magnetic resonance imaging.

PURPOSE: Traumatic knee injury is a common clinical presentation. However, knee internal derangement often goes undiagnosed on physical exam. The authors hypothesize that patients with suprapatellar joint effusion greater than 10 mm anteroposterior diameter on lateral radiograph have a high likelihood of knee internal derangement on magnetic resonance imaging. MATERIALS AND METHODS: A retrospective review of knee radiographs and magnetic resonance imaging in 198 patients age 18-40 years with acute knee injury was performed. Suprapatellar effusion diameter on lateral radiography was correlated to the presence of internal derangement on magnetic resonance imaging. Magnetic resonance imaging anteroposterior effusion size at four locations was correlated to radiographic suprapatellar effusion measurements. RESULTS: Logistic regression showed a positive correlation between radiographic effusion size and the presence of internal derangement on magnetic resonance exams (p value < 0.001). Radiographic effusion > 10 mm was established as a positive test, yielding test sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 55, 96, 93, 71, and 77%, respectively. Statistical analysis showed the radiographic anteroposterior effusion diameter most closely approximated the magnetic resonance effusion diameter at the lateral patellofemoral recess. CONCLUSIONS: This study shows that knee radiography is a highly specific screening test for internal derangement in patients less than 40 years old with acute knee injury. In this patient population, knee effusion > 10 mm on lateral radiograph should prompt consideration for knee magnetic resonance examination. Adopting this approach as a clinical guideline has the potential to decrease delayed diagnosis, improve patient outcomes, and decrease cost-associated disability.

Subtle radiographic signs of hamate body fracture: a diagnosis not to miss in the emergency department.

Hamate fractures are estimated to represent 1.7% of all carpal fractures and can occur at the hamulus (hook) or hamate body depending on mechanism of injury. Fractures of the hamate body can be exceedingly difficult to identify on standard wrist and hand radiographs in the emergency department. If the diagnosis is missed in the emergency department, orthopedic referral is often delayed. This can result in lasting functional disability for the patient, as these fractures have a propensity to destabilize the fourth and fifth carpometacarpal (CMC) joints. In this pictorial essay, we present six radiographic signs indicative of hamate body fracture with computed tomography (CT) imaging correlation. Injury mechanism and fracture classification schemes are portrayed to aid in the understanding of these injuries. Once radiographs raise suspicion for a hamate body fracture, further characterization with CT and orthopedic referral is paramount. Goals of orthopedic management include reestablishment of the fourth and fifth CMC articular surface, stabilization of the CMC joints, and appropriate treatment of concomitant soft tissue injury.

Rapid Magnetic Resonance Imaging Evaluation of Femoral Neck Stress Fractures in a U.S. Active Duty Military Population.

OBJECTIVES: Timely diagnosis of femoral neck stress fractures is important to prevent fracture completion and displacement. We hypothesize that an abbreviated magnetic resonance imaging (MRI) hip examination can diagnose femoral neck stress fractures and that femoral neck stress fractures are common in U.S. military recruits. METHODS: We retrospectively reviewed abbreviated hip MRI examinations performed on active duty patients from November 1, 2013, to August 5, 2014. Patients were referred by primary care providers on the basis of high clinical suspicion. Study variables included presence and grade of femoral neck stress fractures. RESULTS: 229 patients were evaluated with an abbreviated hip MRI. 43 patients (18.8%) were diagnosed with femoral neck stress fractures and 12 patients (5.2%) had bilateral femoral neck stress fractures. All femoral neck stress fractures were on the compressive side. Grading of stress fractures was as follows: 0 Grade I (0%), 8 Grade II (14.5%), 32 Grade III (58.2%), and 15 Grade IV (27.2%). CONCLUSIONS: An abbreviated MR hip examination can diagnose femoral neck stress fractures as well as additional pathologies that explain the patient's symptoms. Femoral neck stress fractures are common in U.S. military personnel.

Dual-Energy Computed Tomography Demonstrating Destructive Calcium Pyrophosphate Deposition Disease of the Distal Radioulnar Joint Mimicking Tophaceous Gout.

Calcium pyrophosphate dihydrate deposition (CPPD) disease is a common etiology of crystalline arthropathy; however, it can manifest in multiple patterns such as acute calcium pyrophosphate (CPP) crystal arthritis, osteoarthritis with CPPD, and chronic CPP crystal inflammatory arthritis. Tumoral or tophaceous-like CPPD is a rare manifestation that is occasionally mistaken for gouty tophus or a soft tissue malignancy. Dual-energy computed tomography (DECT) is a new imaging modality currently utilized in assessing monosodium urate crystal deposition; however, its value in CPPD is uncertain. We describe a case using DECT to diagnose tumoral CPPD mimicking tophaceous gout versus recurrence of a previous synovial sarcoma. The imaging findings on DECT prevented unnecessary surgery to assess for possible malignancy, allowing for the prompt diagnosis of tumoral CPPD. Further studies should be performed to determine the role of DECT in assessing for crystalline deposition disease other than gout.

Suprascapular neuropathy after distal clavicle resection and coracoclavicular ligament reconstruction: a resident's case problem.

STUDY DESIGN: Resident's case problem. BACKGROUND: Acromioclavicular joint pathology is reported to be present in up to 30% of all patients complaining of shoulder dysfunction. The operative approach to treating acromioclavicular joint disease often includes a distal clavicle excision and, in circumstances of acromioclavicular joint instability, reconstruction of the coracoclavicular and/or the acromioclavicular ligament. Surgical complications for these procedures are rare, but potentially include suprascapular neuropathy secondary to the course of the suprascapular nerve posterior to the clavicle prior to entering the supraspinatus fossa. DIAGNOSIS: A 28-year-old Caucasian woman reported directly to an outpatient physical therapy clinic with a complaint of right shoulder weakness. Three years prior, the patient underwent a distal clavicle excision and coracoclavicular ligament reconstruction. A detailed examination, including diagnostic imaging, identified infraspinatus atrophy and weakness, increasing the suspicion for suprascapular nerve injury. Electromyography was ordered to confirm the clinical and imaging diagnosis of suprascapular neuropathy and to rule out other nerve lesions, especially considering the selective atrophy of the infraspinatus muscle without mechanical explanation. DISCUSSION: The clinical decision making and systematic use of diagnostic testing resulted in identifying a rare case of suprascapular neuropathy, selective to the infraspinatus, in a patient who previously underwent a distal clavicle excision and coracoclavicular ligament reconstruction. Without a spinoglenoid cyst or other suprascapular nerve lesion identified on advanced imaging, it is likely that the suprascapular neuropathy identified in this case was related to the surgical procedure. LEVEL OF EVIDENCE: Differential diagnosis, level 4.

Surgical management of retrorectal lesions: what the radiologist needs to know.

OBJECTIVE. The purpose of this article is to highlight the most salient imaging features of retrorectal masses with regard to surgical planning, preoperative biopsy, and identification of nonneoplastic mimickers of malignancy. CONCLUSION. Retrorectal tumors are associated with high morbidity. CT and MRI aid in preoperative planning because surgical resection is the treatment of choice for both benign and malignant entities. Radiologists need to understand the operative techniques currently used for retrorectal tumors because the first attempt at excision is the best chance for complete resection and optimal outcome.

Subtrochanteric femur fractures: review of the complete pathologic spectrum with emphasis on distinguishing imaging features.

Subtrochanteric femur fractures result from a variety of mechanisms of injury and underlying pathologies. Radiologists can play a pivotal role by differentiating the etiology of a subtrochanteric femur fracture, which assists the orthopedic surgeon in choosing the correct method of treatment. To provide this valuable service, one must be familiar with the characteristic radiologic features of the numerous causative etiologies, ranging from Paget disease to underlying bone lesions to iatrogenic fractures.

Sonography of musculoskeletal soft-tissue masses: techniques, pearls, and pitfalls.

OBJECTIVE: The purpose of this article is to review the appropriate use of ultrasound in the workup of soft-tissue masses of the extremities. The normal sonographic appearance of superficial soft tissues, the importance of proper technique in image acquisition, and the characteristic sonographic appearance of certain masses and potential pitfalls are discussed. CONCLUSION: Ultrasound is increasingly being used for the initial evaluation of soft-tissue masses of the extremities. Certain clinical and imaging findings allow diagnosis of selected soft-tissue masses; however, most imaging findings are nonspecific, and further evaluation is necessary. The many potential pitfalls can lead to adverse patient outcomes.

Fool me twice: delayed diagnoses in radiology with emphasis on perpetuated errors.

OBJECTIVE: We hypothesized that delayed diagnoses in radiology are not recognized on subsequent radiologic examinations because of multiple types of errors. MATERIALS AND METHODS: Six hundred fifty-six radiologic examinations with delayed diagnoses were collected from July 1, 2002, to January 31, 2010. Each case was reviewed by two radiologists together, and the diagnostic errors were classified according to our modified scheme with consensus between the radiologists. RESULTS: There were a total of 1269 errors. The range of days elapsed from the initial error in interpretation to the correct diagnosis was 0-4611 days, with an average of 251 days. The percentage for each type of error was 0.9% (n=11) for type 1, 9% (n=110) for type 2, 3% (n=39) for type 3, 42% (n=535) for type 4, approximately 0% (n=1) for type 5, 2% (n=29) for type 6, 5% (n=59) for type 7, 2% (n=20) for type 8, 7% (n=92) for type 9, 22% (n=288) for type 10, 0.5% (n=6) for type 11, and 6% (n=79) for type 12. The correct diagnoses were not recognized on subsequent radiologic examinations in 196 of 656 cases (30%). CONCLUSION: Delayed diagnoses were not recognized on subsequent radiologic examinations in about one third of the cases. The most common types of error were underreading, satisfaction of search, faulty reasoning, and location of the finding.

Greater trochanteric fracture with occult intertrochanteric extension.

Proximal femoral fractures are frequently encountered in the emergency department (ED). Prompt diagnosis is paramount as delay will exacerbate the already poor outcomes associated with these injuries. In cases where radiography is negative but clinical suspicion remains high, magnetic resonance imaging (MRI) is the study of choice as it has the capability to depict fractures which are occult on other imaging modalities. Awareness of a particular subset of proximal femoral fractures, namely greater trochanteric fractures, is vital for both radiologists and clinicians since it has been well documented that they invariably have an intertrochanteric component which may require surgical management. The detection of intertrochanteric or cervical extension of greater trochanteric fractures has been described utilizing MRI but is underestimated with both computed tomography (CT) and bone scan. Therefore, if MRI is unavailable or contraindicated, the diagnosis of an isolated greater trochanteric fracture should be met with caution. The importance of avoiding this potential pitfall is demonstrated in the following case of an elderly woman with hip pain and CT demonstrating an isolated greater trochanteric fracture who subsequently returned to the ED with a displaced intertrochanteric fracture.

Disruption of a patellar tendon repair.

The patient was a 38-year-old man evaluated by a physical therapist 14 weeks after repair of the left patellar tendon. The physical therapist requested radiographs, which revealed findings consistent with a patellar tendon retear. The radiologist recommended further evaluation with magnetic resonance imaging, which showed a left patellar tendon tear.

Imaging of hemorrhagic fever with renal syndrome: a potential bioterrorism agent of military significance.

Hemorrhagic fever with renal syndrome (HFRS) is a potentially fatal infectious disease with worldwide distribution. Its etiologic agents are viruses of the genus Hantavirus of the virus family Bunyaviridae. Hypothetical ease of production and distribution of these agents, with their propensity to incapacitate victims and overwhelm health care resources, lend themselves as significant potential biological agents of terrorism. HFRS has protean clinical manifestations, which may mimic upper respiratory tract infection, nephrolithiasis, and Hantavirus pulmonary syndrome and may delay proper treatment. Sequelae of HFRS, such as hemorrhage, acute renal failure, retroperitoneal edema, pancreatitis, pulmonary edema, and neurologic symptoms, can be detected by different imaging modalities. Medical providers caring for HFRS patients must be aware of its radiologic features, which may help to confirm its clinical diagnosis. In this article, the authors review the epidemiology, pathophysiology, clinical presentation, diagnosis, treatment, and complications of HFRS.

Isolated bone infarct of the calcaneus after fracture.

The calcaneus has a rich vascular supply; therefore, avascular necrosis of the calcaneus is extremely rare. We report the first case of bone infarct of the calcaneus 9 months after a fracture. We also review the literature on osteonecrosis of the calcaneus to offer potential mechanisms for bone infarction in the calcaneus after a fracture.

Magnetic resonance diagnosis of tarsal tunnel syndrome due to flexor digitorum accessorius longus and peroneocalcaneus internus muscles.

Anomalous muscles of the ankle are common. Although they are often asymptomatic, they can sometimes cause tarsal tunnel syndrome. We report a case of tarsal tunnel syndrome due to flexor digitorum accessorius longus and peroneocalcaneus internus muscles diagnosed on magnetic resonance imaging. Recognition of the most common accessory muscles of the ankle on magnetic resonance imaging and tarsal tunnel syndrome are also reviewed.

Costovertebral fracture dislocations: important radiographically difficult diagnosis.

The authors' aim is to report the appearance of fracture dislocations of the costovertebral joint. We will review the pertinent anatomy of the costovertebral articulation, summarize the current literature, report our experience and the imaging appearance of costovertebral joint fracture dislocations, and discuss important concepts of the costovertebral joint, as it relates to thoracic spine fractures.