Jacob Mandell

Stress fractures of the foot and ankle, part 1: biomechanics of bone and principles of imaging and treatment

A stress fracture is a focal failure of bone induced by the summation of repetitive forces, which overwhelms the normal bone remodeling cycle. This review, the first of two parts, discusses the general principles of stress fractures of the foot and ankle. This includes bone structure, biomechanics of stress applied to bone, bone remodeling, risk factors for stress fracture, and general principles of imaging and treatment of stress fractures. Cortical bone and trabecular bone have a contrasting macrostructure, which leads to differing resistances to externally applied forces. The variable and often confusing imaging appearance of stress fractures of the foot and ankle can largely be attributed to the different imaging appearance of bony remodeling of trabecular and cortical bone. Risk factors for stress fracture can be divided into intrinsic and extrinsic factors. Stress fractures subject to compressive forces are considered low-risk and are treated with activity modification and correction of any modifiable risk factors. Stress fractures subject to tensile forces and/or located in regions of decreased vascularity are considered high risk, with additional treatment options including restricted weight-bearing or surgery.

Integration of a Zero-footprint Cloud-based Picture Archiving and Communication System with Customizable Forms for Radiology Research and Education

RATIONALE AND OBJECTIVES The purpose of this study was to integrate web-based forms with a zero-footprint cloud-based Picture Archiving and Communication Systems (PACS) to create a tool of potential benefit to radiology research and education. MATERIALS AND METHODS Web-based forms were created with a front-end and back-end architecture utilizing common programming languages including Vue.js, Node.js and MongoDB, and integrated into an existing zero-footprint cloud-based PACS. RESULTS The web-based forms application can be accessed in any modern internet browser on desktop or mobile devices and allows the creation of customizable forms consisting of a variety of questions types. Each form can be linked to an individual DICOM examination or a collection of DICOM examinations. CONCLUSIONS Several uses are demonstrated through a series of case studies, including implementation of a research platform for multi-reader multi-case (MRMC) studies and other imaging research, and creation of an online Objective Structure Clinical Examination (OSCE) and an educational case file.

Stress fractures of the foot and ankle, part 2: site-specific etiology, imaging, and treatment, and differential diagnosis

Stress fractures of the foot and ankle are a commonly encountered problem among athletes and individuals participating in a wide range of activities. This illustrated review, the second of two parts, discusses site-specific etiological factors, imaging appearances, treatment options, and differential considerations of stress fractures of the foot and ankle. The imaging and clinical management of stress fractures of the foot and ankle are highly dependent on the specific location of the fracture, mechanical forces acting upon the injured site, vascular supply of the injured bone, and the proportion of trabecular to cortical bone at the site of injury. The most common stress fractures of the foot and ankle are low risk and include the posteromedial tibia, the calcaneus, and the second and third metatarsals. The distal fibula is a less common location, and stress fractures of the cuboid and cuneiforms are very rare, but are also considered low risk. In contrast, high-risk stress fractures are more prone to delayed union or nonunion and include the anterior tibial cortex, medial malleolus, navicular, base of the second metatarsal, proximal fifth metatarsal, hallux sesamoids, and the talus. Of these high-risk types, stress fractures of the anterior tibial cortex, the navicular, and the proximal tibial cortex may be predisposed to poor healing because of the watershed blood supply in these locations. The radiographic differential diagnosis of stress fracture includes osteoid osteoma, malignancy, and chronic osteomyelitis.

Clinical Applications of a CT Window Blending Algorithm: RADIO (Relative Attenuation-Dependent Image Overlay)

A methodology is described using Adobe Photoshop and Adobe Extendscript to process DICOM images with a Relative Attenuation-Dependent Image Overlay (RADIO) algorithm to visualize the full dynamic range of CT in one view, without requiring a change in window and level settings. The potential clinical uses for such an algorithm are described in a pictorial overview, including applications in emergency radiology, oncologic imaging, and nuclear medicine and molecular imaging.

Traffic Jam in the Duodenum: Imaging and Pathogenesis of Bouveret Syndrome

A 90-year-old woman with a history of cholelithiasis and chronic cholecystitis presented to the hospital with nausea, bilious vomiting, and anorexia for 3 days. The patient denied fevers, chills, hematemesis, hematochezia, or melena. Physical examination was notable for an uncomfortable woman with epigastric tenderness. An abdominal radiograph was obtained and demonstrated pneumobilia and an enlarged gastric bubble (Figure 1). Subsequent computed tomography with intravenous contrast material was obtained and demonstrated a gallstone in the proximal duodenum causing gastric distention, consistent with Bouveret syndrome (Figure 2). The patient underwent endoscopic-guided lithotripsy with resolution of symptoms.

Computed Tomography Window Blending: Feasibility in Thoracic Trauma

RATIONALE AND OBJECTIVES This study aims to demonstrate the feasibility of processing computed tomography (CT) images with a custom window blending algorithm that combines soft-tissue, bone, and lung window settings into a single image; to compare the time for interpretation of chest CT for thoracic trauma with window blending and conventional window settings; and to assess diagnostic performance of both techniques. MATERIALS AND METHODS Adobe Photoshop was scripted to process axial DICOM images from retrospective contrast-enhanced chest CTs performed for trauma with a window-blending algorithm. Two emergency radiologists independently interpreted the axial images from 103 chest CTs with both blended and conventional windows. Interpretation time and diagnostic performance were compared with Wilcoxon signed-rank test and McNemar test, respectively. Agreement with Nexus CT Chest injury severity was assessed with the weighted kappa statistic. RESULTS A total of 13,295 images were processed without error. Interpretation was faster with window blending, resulting in a 20.3% time saving (P < .001), with no difference in diagnostic performance, within the power of the study to detect a difference in sensitivity of 5% as determined by post hoc power analysis. The sensitivity of the window-blended cases was 82.7%, compared to 81.6% for conventional windows. The specificity of the window-blended cases was 93.1%, compared to 90.5% for conventional windows. All injuries of major clinical significance (per Nexus CT Chest criteria) were correctly identified in all reading sessions, and all negative cases were correctly classified. All readers demonstrated near-perfect agreement with injury severity classification with both window settings. CONCLUSIONS In this pilot study utilizing retrospective data, window blending allows faster preliminary interpretation of axial chest CT performed for trauma, with no significant difference in diagnostic performance compared to conventional window settings. Future studies would be required to assess the utility of window blending in clinical practice.

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.

Iliopsoas bursal extension of lipohemarthrosis: A novel imaging finding associated with hip fracture

Lipohemarthrosis is well known to be associated with intra-articular fractures throughout the body. Despite the relatively common occurrence of hip fracture and the frequency of communication between the hip joint and iliopsoas bursa, to the best of our knowledge, a fat-fluid level involving the iliopsoas bursa secondary to a hip fracture has not previously been reported. The following is a case report of a 48-year-old male who sustained an acute femoral neck fracture and was found to have distension of the iliopsoas bursa with a fat-fluid level resulting from extra-capsular extension of a lipohemarthrosis. The imaging findings, relevant anatomy, and potential importance of this finding for the detection of hip fracture are discussed.

Traumatic Hip Dislocation: What the Orthopedic Surgeon Wants to Know

Hip dislocation is an important orthopedic emergency usually seen in young patients who have experienced high-energy trauma, often resulting in significant long-term morbidity. Rapid identification and reduction is critical, as prolonged dislocation increases the risk of developing avascular necrosis of the femoral head, and posttraumatic osteoarthritis is a common complication, even in the absence of associated fractures. Identification and timely management of hip dislocation are highly dependent on imaging, both at presentation and after attempted reduction. It is imperative for the radiologist to understand imaging features that guide management of hip dislocation to ensure timely identification, characterization, and communication of clinically relevant results. Although the importance of prompt identification of hip dislocation is universally recognized, the significance of imaging features that guide correct management and are thought to prevent complications is less emphasized in the radiology literature. In this article, the authors review the anatomy of the hip, common injury mechanisms for various types of dislocations, and imaging findings for associated injuries. They review the most commonly used classification systems and propose a simplified checklist approach to hip dislocation to aid rapid interpretation and communication of the most clinically relevant imaging features to the treating orthopedic surgeon. ©RSNA, 2017.

The Lumbar Neural Foramen and Transforaminal Epidural Steroid Injections: An Anatomic Review With Key Safety Considerations in Planning the Percutaneous Approach

OBJECTIVE The purpose of this article is to review the anatomy of the lumbar neural foramen and to describe techniques of transforaminal epidural steroid injections with emphasis on safety. Rare cases of paraplegia have been reported. CONCLUSION Although no consensus currently exists about which approach is the safest, knowledge of the foraminal anatomy is a key consideration when choosing a needle approach for transforaminal epidural steroid injections.