Cone-Beam CT of the Extremities in Clinical Practice.

Cone-beam CT (CBCT) is a promising tool with increasing applications in musculoskeletal imaging due to its ability to provide thin-section CT images of the appendicular skeleton and introduce weight bearing, which accounts for loading forces that typically interact with and affect this anatomy. CBCT devices include an x-ray source directly opposite a digital silicon detector panel that performs a single rotation around an object of interest, obtaining thin-section images. Currently, the majority of research has been focused on the utility of CBCT with foot and ankle pathologic abnormalities, due to the complex architectural arrangement of the tarsal bones and weight-bearing nature of the lower extremities. Associated software can provide a variety of options for image reconstruction, including metal artifact reduction, three-dimensional biometric measurements, and digitally reconstructed radiographs. Advancements in this technology have allowed imaging of the knee, hip, hand, and elbow. As more data are published, it is becoming evident that CBCT provides many additional benefits, including fast imaging time, low radiation dose, lower cost, and small equipment footprint. These benefits allow placement of CBCT units outside of the traditional radiology department, including the orthopedic clinic setting. These technologic developments have motivated clinicians to define the scope of CBCT for diagnostics, surgical planning, and longitudinal imaging. As efforts are made to create standardized protocol and measurements, the current understanding and surgical approach for various orthopedic pathologic conditions will continue to shift, with the hope of improving outcomes. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Does MRI alter management in patients 60 years and older with chronic knee pain: correlation with radiographs and clinical parameters.

OBJECTIVE: To determine if MRI altered management in patients ≥ 60 years old with chronic knee pain. MATERIALS AND METHODS: Consecutive patients ≥ 60 years old with knee MRI and radiographs within 90 days were included. Exclusion criteria included mass/malignancy, recent trauma, and infection. Standing AP and PA flexion views were evaluated using Kellgren-Lawrence (KL) and International Knee Documentation Committee (IKDC) scales. Pertinent clinical history was recorded. MRIs were considered to alter management if subchondral fracture was identified or subsequent arthroscopy was performed due to an MRI finding. RESULTS: Eighty-five knee MRI/radiograph exams were reviewed; mean 68.2 years (60-88), 47:38 F:M. Twenty knee MRIs (24%) had either a subchondral fracture (n = 9) or meniscal tear (n = 11) prompting arthroscopy. On PA flexion view, 0/20 of these studies had KL grade 4 and 70% (14/20) had KL grade 0-1 compared to the remaining MRIs having 15.4% (10/65) KL grade 4 and 38.5% (25/65) KL grade 0-1 (p = 0.03). A 10-pack-year tobacco history, 38% vs 18%, was associated with a subchondral fracture or arthroscopy (p = 0.06). Subchondral fractures were more prevalent in older patients (mean 72.4 vs 67.7 years; p = 0.03). CONCLUSION: In patients ≥ 60 years old with chronic knee pain, MRI altered management in ~ 24% of cases; 70% in patients with KL grade 0-1, and none in patients with KL grade 4. MRI may benefit older patients with minimal osteoarthritis but not those with end-stage disease. Patients with ≥ 10 pack years of smoking may also benefit from MRI.

CT-guided quadratus femoris injection for ischiofemoral impingement.

OBJECTIVES: To describe the technique, efficacy, and safety of CT-guided quadratus femoris injection with corticosteroid and local anesthetic for the treatment of ischiofemoral impingement in a series of cases at our institution. METHODS: Cases of CT-guided quadratus femoris injections from 2000 to 2021 were identified in the enterprise-wide electronic medical record of our institution. Patient charts and our institutional picture archiving and communication system (PACS) were searched for demographics, pain level on a 0-10 scale before and immediately following the procedure, procedure technique, and follow-up outcomes if available. RESULTS: There were 13 cases among 12 patients with clinical and imaging findings of ischiofemoral impingement included in this study. Of the 12 patients, 10 were female and two were male. There were eight posterior approaches and five posterolateral approaches. Of the 13 cases, 11 resulted in immediate pain reduction. The median reduction in pain score was four (average 3.46, range 0-8.5). There was no statistically significant difference in pain reduction between the posterior approach cases and the posterolateral approach cases. No cases reported immediate complications or increases in pain score. Of the 12 cases, seven resulted in at least 1 month of pain relief, three had subsequent surgeries, and three had no follow-up. CONCLUSION: CT-guided quadratus femoris injection is safe and effective for treating ischiofemoral impingement. Further and larger scale study is needed to fully delineate differences in technique effectiveness. KEY POINTS: • CT-guided quadratus femoris injection is safe and effective for treating ischiofemoral impingement. • We found no statistically significant difference in pain reduction between the posterior approach and the posterolateral approach.

Carbon-fiber-reinforced polyetheretherketone orthopedic implants in musculoskeletal and spinal tumors: imaging and clinical features.

Carbon-fiber-reinforced polyetheretherketone (CFR-PEEK) orthopedic implants are gaining popularity in oncologic applications as they offer many potential advantages over traditional metallic implants. From an imaging perspective, this instrumentation allows for improved evaluation of adjacent anatomic structures during radiography, computed tomography (CT), and magnetic resonance imaging (MRI). This results in improved postoperative surveillance imaging quality as well as easier visualization of anatomy for potential image-guided percutaneous interventions (e.g., pain palliation injections, or ablative procedures for local disease control). CFR-PEEK devices are also advantageous in radiation oncology treatment due to their decreased imaging artifact during treatment planning imaging and decreased dose perturbation during radiotherapy delivery. As manufacturing processes for CFR-PEEK materials continue to evolve and improve, potential orthopedic applications in the spine and appendicular skeleton increase. An understanding of the unique properties of CFR-PEEK devices and their impact on imaging is valuable to radiologists delivering care to orthopedic oncology patients in both the diagnostic and interventional settings. This multidisciplinary review aims to provide a comprehensive insight into the radiologic, surgical, and radiation oncology impact of these innovative devices.

Angiolipoma: a review of 778 lesions in 344 patients.

BACKGROUND: Angiolipomas are benign subcutaneous nodules that are commonly multifocal and easily overlooked by those not familiar with their appearance. The objective of this study was to identify the spectrum of the clinical and imaging features of this lesion, to include MR, CT, and US features. METHODS: A retrospective review of our institutional pathology database for biopsy-proven cases of angiolipoma between January 1, 2019, through December 31, 2021, was done. We identified 334 patients who underwent surgical resection of 788 individual lesions. MR imaging studies were available in 43 cases, CT in 39 cases, and ultrasound imaging in 72 cases. Clinical features (patient age, gender, surgical indication, number of lesions) were reviewed. Imaging feature analysis included the anatomic location, content of fat, vascularity, and modality-specific imaging features. RESULTS: All 778 angiolipomas were located in the subcutaneous tissues (median size, 2.4 cm, range 0.4-7.7 cm), with over 51% located in the upper extremity. The most common presentation was a symptomatic mass or slowly growing symptomatic mass. Imaging showed a subcutaneous lesion with a lobulated bean shape, which typically abutted the skin. Intralesional fat was identified in 85% of lesions on CT and MRI. Vessels were commonly seen on CT and MR, with enhancement best seen on MR. On US, lesions were heterogeneous and mildly hyperechoic, most often with no identifiable vascularity. CONCLUSION: Angiolipomas typically have characteristic imaging features. Awareness of this diagnosis and the spectrum of its imaging features is important and can facilitate a definitive diagnosis.

Percutaneous biopsy of musculoskeletal tumors and the potential for needle tract seeding: technical considerations, current controversies, and outcomes.

Multidisciplinary communication and planning between the musculoskeletal radiologist and orthopedic oncologist are essential for proper biopsy planning when a primary musculoskeletal malignancy is suspected. Image-guided percutaneous biopsy allows for real-time visualization of the biopsy needle and surrounding structures, combining high diagnostic accuracy with safety and cost-effectiveness. However, determining a surgically optimal biopsy trajectory for a mass can be technically challenging due to critical surrounding anatomy or challenging needle approach angles. Inappropriately placed biopsies can have serious repercussions on patient function and oncological survival. The potential for needle tract seeding and local recurrence after biopsy of sarcoma has been central to the debate regarding the need for excision of the biopsy tract. This multidisciplinary review highlights current controversies in the field, including the issue of core needle biopsy tracts and their excision, technical considerations and advances in image-guidance in the setting of challenging biopsies, advances in histopathological diagnostics with implications for targeted therapy in sarcoma, as well as surgical and oncological outcomes after needle tract biopsy.

MRI Evaluation of Patients Before and After Interventions for Benign Prostatic Hyperplasia: An Update.

Transurethral resection of the prostate is the most commonly performed procedure for the management of patients with lower urinary tract symptoms attributed to benign prostatic hyperplasia (BPH). However, in recent years, various minimally invasive surgical therapies have been introduced to treat BPH. These include laser-based procedures such as holmium laser enucleation of the prostate and photoselective vaporization of the prostate as well as thermal ablation procedures such as water vapor thermal therapy (Rezum), all of which result in volume reduction of periurethral prostatic tissue. In comparison, a permanent metallic device (UroLift) can be implanted to pull open the prostatic urethra without an associated decrease in prostate size, and selective catheter-directed prostate artery embolization results in a global decrease in prostate size. The goal of this article is to familiarize radiologists with the underlying anatomic changes that occur in BPH as visualized on MRI and to describe the appearance of the prostate on MRI performed after these procedures. Complications encountered on imaging after these procedures are also discussed. Although MRI is not currently used in the routine preprocedural evaluation of BPH, emerging data support a role for MRI in predicting postprocedure outcomes.

A novel meniscofemoral ligament variant intra-substance to the PCL.

While much detail is known about each anatomic structure of the knee and its contributory effect on biomechanics, our understanding is still evolving. In particular, the function of the meniscofemoral ligaments and their anatomical variants have yet to be fully described. In this report, a never-before-described anatomical meniscofemoral ligament variant intra-substance to the PCL is presented. Arthroscopists should be aware of the novel variant as a growing number of studies have demonstrated the biomechanical importance of the meniscofemoral ligaments in protecting the lateral meniscus and supporting the function of the PCL.Level of Evidence: IV.

Ulnar shaft stress fractures in fast-pitch softball pitchers: a case series and proposed mechanism of injury.

BACKGROUND: Stress fractures of the upper extremities in athletes are important injuries for radiologists to appreciate despite being far less common than stress fractures of the lower extremities. Among upper extremity stress fractures, those involving the olecranon have been well described in overhead pitching athletes. Isolated stress fractures of the ulnar shaft however are less commonly reported in the literature and considered to be rare. We have observed a correlation between young patients with ulnar shaft stress fractures and the activity of fast-pitch softball pitching. CASE REPORTS: In this series, we present the imaging findings in four cases of ulnar shaft stress fractures in softball pitchers who presented with insidious onset forearm pain. Furthermore, a review of the literature focusing on softball pitching mechanics is provided to offer a potential underlying mechanism for the occurrence and location of these injuries. CONCLUSION: An awareness of the imaging appearance of ulnar shaft stress fractures along with an understanding of its proposed mechanism will facilitate accurate and timely imaging diagnosis of this injury by the radiologist.

Efficacy and safety of bone marrow aspiration and biopsy using fluoroscopic guidance and a drill-powered needle: clinical experience from 775 cases.

OBJECTIVES: To evaluate the efficacy and safety of performing a fluoroscopically guided bone marrow aspiration and biopsy (BMAB) using a drill-powered needle in a large patient population. METHODS: This retrospective study received institutional review board approval with a waiver of patient informed consent. We identified all BMAB procedures from August 2012 through December 2016 performed at our institution using fluoroscopic guidance and a drill-powered needle. Clinical diagnosis, patient age, patient gender, biopsy site, biopsy needle gauge, bone marrow aspirate volume, bone marrow core biopsy length, patient platelet count, conscious sedation details, complications, and diagnostic adequacy were investigated for each case and summarized. RESULTS: A total of 775 BMAB procedures were performed and analyzed. These were performed in 436 female patients and 339 male patients ranging in age between 16 and 91 years (average age of 53 years). Samples obtained from the procedures in our series were diagnostic in 95.0% of cases. The complication rate for our series was 0.3%. CONCLUSIONS: The use of fluoroscopic guidance and a drill-powered needle for bone marrow aspiration and biopsy is a safe and efficacious procedure. KEY POINTS: • Fluoroscopy can be utilized for imaging guidance during bone marrow aspiration and biopsy. • The use of fluoroscopic guidance and a drill-powered needle for bone marrow aspiration and biopsy has a high diagnostic yield. • The procedure has an excellent patient safety profile.

Desmoplastic Fibroblastoma: An Uncommon Tumor With a Relatively Characteristic MRI Appearance.

OBJECTIVE. We undertook this study to determine the radiologic features of desmo-plastic fibroblastoma. MATERIALS AND METHODS. We reviewed available radiologic images for 29 pathologically confirmed desmoplastic fibroblastomas, including images from MRI, radiography, ultrasound (US), and CT. RESULTS. The patient population included 14 women and 15 men (mean age, 60 years; range, 23-96 years). Typically, lesions were oval or lobulated and relatively small (mean, 5.6 cm). In 14 of the 22 cases that included patient histories, lesions had grown slowly, with two eventually causing pain. The remaining eight were discovered incidentally. All lesions involved or were below the deep fascia. Lesions were well-defined and associated with muscle (45%), deep fascia (28%), joint (21%), or tendon (7%). MR images were available in 26 cases; 14 included unenhanced and contrast-enhanced studies. On MRI imaging all lesions were well-defined and adjacent to dense connective tissue. On T1-weighted images, lesions showed varying amounts of low and intermediate signal intensity similar to that of tendon and skeletal muscle, respectively. On fluid-sensitive images, lesions were more heterogeneous, generally showing a wider spectrum of decreased to intermediate signal intensity. On contrast-enhanced MR images, enhancement was characteristically peripheral and septal with patchy areas of homogeneity. In the 10 cases with radiographs, images showed negative findings or a nonmineralized mass. The 10 available ultrasound studies showed mixed echogenicity. In eight patients, unenhanced CT showed lesions having attenuation similar to that of skeletal muscle. CONCLUSION. Desmoplastic fibroblastoma is an uncommon neoplasm with a relatively characteristic MRI appearance.

Iatrogenic humeral anatomic neck fracture after intraosseous vascular access.

Intraosseous infusion has become a key tool in the resuscitation of critically ill or injured patients, both in pre-hospital settings and in emergency departments. Intraosseous access is obtained through the percutaneous placement of a needle into the medullary space of a bone, thereby allowing access into the systemic venous circulation via the medullary space, which is essential to treat patients in shock, cardiac arrest, airway compromise, or major trauma. This becomes critically important when obtaining conventional intravenous access is difficult or impossible. Few cases of iatrogenic fracture have been reported for intraosseous access in the tibia and no case to-date has been reported of iatrogenic fracture secondary to humeral access. We report a case of a 55-year-old patient being resuscitated emergently with proximal humeral intraosseous infusion for cardiac and respiratory arrest secondary to status epilepticus. After successful resuscitation and removal of the intraosseous cannula, the patient noted new-onset shoulder pain. The patient was ultimately diagnosed with an iatrogenic fracture of the anatomic neck of the humerus through the intraosseous needle tract when the appropriate history was obtained in conjunction with cross-sectional imaging. As the use of intraosseous access expands, such fractures may well be seen more frequently. Intraosseous access is limited to the period of resuscitation and the cannula is often not present at the time of imaging. It is important for radiologists to recognize the findings related to intraosseous access as well as this complication with its characteristic locations and morphology.

A novel technique for retrieval of a broken biopsy needle.

A broken needle is a rare complication of bone biopsy. We describe an easily applied technique of retrieval of a retained biopsy needle fragment using a cannulated drill typically used for internal fixation of femoral neck fractures. This approach allows for removal under moderate conscious sedation and can be performed by a radiologist using fluoroscopic or CT-fluoroscopic guidance in the radiology suite.

The Radiologist's Primer to Imaging the Noncuff, Nonlabral Postoperative Shoulder.

Many radiologists are familiar with the preoperative imaging assessment of patients with labral tears, rotator cuff abnormalities, and end-stage arthritis, as well as the subsequent primary reconstructions and repairs commonly encountered in routine clinical management. However, the second-line surgical procedures and augmentation procedures performed for refractory or recurrent shoulder instability and the extra-articular surgical procedures of the shoulder girdle may challenge even the most experienced musculoskeletal radiologist. Knowledge of the indications, surgical techniques, expected postoperative imaging appearance, and complications of these uncommon shoulder girdle reconstructions and repairs will aid the radiologist in both the pre- and postoperative assessment of the injured shoulder. This article is divided into two parts. In the first part, procedures performed for shoulder instability are addressed, including capsular shift, Bristow-Latarjet coracoid transfer, remplissage, and humeral head allografts. In the second part, the imaging findings of extra-articular procedures of the shoulder girdle are reviewed, including biceps tenodesis, os acromiale fixation, and coracoclavicular ligament reconstruction. ©RSNA, 2017.

Postoperative Imaging of the Knee Extensor Mechanism.

The extensor mechanism of the knee plays an important role in many movements of the lower extremity. Although its main function is to extend the knee, it also stabilizes the patellofemoral joint and resists passive flexion of the knee when landing from jumping. Pathologic conditions of the extensor mechanism can be acute or chronic, and they can negatively affect daily activities. Fortunately, many surgical treatments are available aimed at restoring function to the injured extensor mechanism. Understanding the surgical techniques and common complications of these procedures enables the radiologist to recognize expected and unexpected postoperative imaging appearances.

Impact of an Interactive Diagnostic Case Simulator on a Medical Student Radiology Rotation.

OBJECTIVE: The objective of our study was to assess the short-term impact of adding an interactive simulator to a medical student radiology clerkship. We hypothesized that transitioning students from passive observers to active participants in the reading room would create an appealing and effective learning experience for the current generation of students. MATERIALS AND METHODS: An interactive workstation that provided diagnostic simulations of 84 cases selected to maximize exposure to important diagnoses in musculoskeletal (MSK) radiology was created. From February 2015 through July 2016, 83 students on the radiology elective rotated through MSK: 40 in the traditional observational role and 43 with the MSK simulator. At the end of the rotation, all students completed general radiology and MSK-based competency examinations. The students who used the interactive workstation completed a survey about their experience. RESULTS: MSK competency scores were significantly better for students who rotated with the interactive workstation compared with students in the traditional observational role (mean scores, 71% and 51%, respectively; p < 0.0001). There was no difference in end-of-rotation general competency scores between the groups (mean, 86% and 85%; p = 0.32). Ninety-one percent of students reported the simulator had at least a moderately positive impact on their radiology experience. All students (100%) reported that learning was improved and recommended establishing workstations for other subspecialties. Twenty-one percent of students reported that their experience using the simulator had a positive impact on considering radiology as a career choice. CONCLUSION: Using a reading room-based diagnostic radiology case simulator improves medical student learning, enables self-directed learning, and improves overall experience on the radiology clerkship, positively impacting consideration of radiology as a career.

Biopsy of CT-Occult Bone Lesions Using Anatomic Landmarks for CT Guidance.

OBJECTIVE: The purpose of this study is to evaluate the histopathologic diagnostic yield, sample size, procedural time, and dose-length product (DLP) for the biopsy of CT-occult lesions found at MRI or PET or both. MATERIALS AND METHODS: A retrospective review of our radiology information system for biopsies of CT-occult lesions using CT guidance from January 1, 2010, through December 31, 2014, was performed and compared with a selection of CT-guided biopsies of CT-evident bone lesions during the same period. The data were then evaluated for diagnostic yield of histopathologic diagnosis, procedural time, use of sedation medication, DLP, and size of specimens obtained. RESULTS: A total of 30 CT-occult biopsies met the inclusion criteria. Twenty-seven of those biopsies had results that were concordant with the patient's primary histopathologic diagnosis, imaging findings, and clinical course. In the CT-evident lesion group, concordant histopathologic abnormalities were identified in 27 of 30 patients. There was a statistically significant increase in number of samples obtained for the CT-evident lesions compared with CT-occult lesions. There was no statistically significant difference in total specimen length, DLP, number of CT scans, procedural time, or use of sedation medication between the CT-occult and CT-evident biopsy groups. CONCLUSION: Biopsy of CT-occult lesions using anatomic landmarks achieves diagnostic yields similar to those for CT-guided biopsy of CT-evident lesions.

Drill-Assisted Biopsy of the Axial and Appendicular Skeleton: Safety, Technical Success, and Diagnostic Efficacy.

The purpose of this study was to evaluate the safety, technical success rate, and diagnostic efficacy of drill-assisted axial and appendicular bone biopsies. During a 3-y period, 703 drill-assisted biopsies were performed. The cohort included 54.2% men, with a mean age of 57.6 y ± 17.1. Median lesion volume was 10.9 mL (interquartile range, 3.4-30.2 mL). Lesions were lytic (31.7%), sclerotic (21.2%), mixed lytic and sclerotic (27.7%), or normal radiographic bone quality (19.3%). No complications were reported. The technical biopsy success rate was 99.9%. Crush artifact was present in 5.8% of specimens submitted for surgical pathologic examination, and 2.1% of specimens were inadequate for histologic evaluation.