Dual-energy CT applications in musculoskeletal disorders.

Dual-energy CT (DECT) is an exciting application in CT technology conferring many advantages over conventional single-energy CT at no additional with comparable radiation dose to the patient. Various emerging and increasingly established clinical DECT applications in musculoskeletal (MSK) imaging such as bone marrow oedema detection, metal artefact reduction, monosodium urate analysis, and collagen analysis for ligamentous, meniscal, and disc injuries are made possible through its advanced DECT post-processing capabilities. These provide superior information on tissue composition, artefact reduction and image optimization. Newer DECT applications to evaluate fat fraction for sarcopenia, Rho/Z application for soft tissue calcification differentiation, 3D rendering, and AI integration are being assessed for future use. In this article, we will discuss the established and developing applications of DECT in the setting of MSK radiology as well as the basic principles of DECT which facilitate them.

Imaging Review of Hockey-Related Upper Extremity Injuries.

Ice hockey is a fast-paced contact sport with a high incidence of injuries. Upper extremity injury is one of the most common regions of the body to be injured in hockey. This imaging review will equip the radiologist with a knowledge of the more common and severe upper extremity injuries that occur in this sport.

Imaging Review of Hockey-related Lower Extremity Injuries.

Hockey is a fast-paced contact sport with a high incidence of injuries. Although injuries are more frequent among elite players, recreational hockey injuries are a common issue faced by primary care and emergency physicians. Lower extremity injuries in hockey are particularly important because they account for approximately a third of all injuries and > 60% of all overuse injuries. This pictorial review provides the general and specialty trained radiologist with a knowledge of the patterns of lower extremity injury that occur in ice hockey.

Imaging of Hockey-related Injuries of the Head, Neck, and Body.

Hockey is a demanding contact sport with growing popularity around the world. This article is part of a review series in this issue of Seminars in Musculoskeletal Radiology that summarizes epidemiological research on the patterns of ice hockey injuries as well as provides pictorial examples for a radiologist's perspective. We focus on non-extremity pathologies which encompass many of the most devastating injuries of hockey, namely those involving the head, neck, face, spine, and body.

The Role of a Virtual Noncalcium Dual-Energy CT Application in the Detection of Bone Marrow Edema in Peripheral Osteomyelitis.

Purpose: To determine the sensitivity and specificity of dual-energy CT (DECT) virtual noncalcium images (VNCa) with bone and soft tissue reconstructions in the diagnosis of osteomyelitis. Materials & Methods: Between December 1, 2014 to December 1, 2020, 91 patients who had 99 DECT performed for a clinical indication of osteomyelitis with corresponding MRI, triphasic bone scan and/or white blood cell scintigraphy with CT/SPECT performed either 2 weeks before or 1 month after the DECT were retrospectively identified. The presence or absence of osteomyelitis was established using a second imaging test, bone biopsy or surgery. Two radiologists interpreted VNCa images alone and with bone and soft tissue reconstructions for osteomyelitis. Fleiss k statistics was used to assess inter-level agreement. Results: Osteomyelitis was present in 26 cases (26.2%), of which 4 cases (4%) had co-existing septic arthritis. DECT was performed at the following sites: ankle/foot (n = 59), calf (n = 12), knee (n = 3), thigh (n = 7), hip (n = 9), pelvis (n = 6), wrist/hand (n = 1), and shoulder (n = 2). Sensitivity with VNCa images alone was 53.8% and 73.1% and specificity was 84.9% and 71.2%. Sensitivity with VNCa images and bone and soft tissue reconstructions was 80.8% and 80.8% and specificity was 80.8% and 72.6%. Interobserver agreement was 76.7% (76 of 99 cases), for VNCa images alone (k = .487), and 66.7% (66 of 99 patients) for bone and soft tissue reconstructions with VNCa images together (k = .390). Conclusion: When VNCa images were combined with bone and soft tissue reconstructions, there is improved sensitivity in the diagnosis of osteomyelitis.

Repetitive trauma-induced extra-nuchal-type fibroma.

A nuchal-type fibroma is a rare, benign fibrous tumour that typically occurs in the posterior neck along the midline, but can occur in extra-nuchal locations, most commonly in the back, shoulder and face. We present a biopsy-proven case that arose as a result of heavy gym-related activities. In particular, a heavy barbell was rested on his vertebral prominence at the level of C7/T1 during leg squatting. Repetitive trauma as a cause for extra-nuchal-type fibromas has been sparsely reported, but we suggest that sustained high pressure is an additional required feature. Although this lesion was in the posterior neck, it was contained entirely within the subcutaneous tissues without involvement of the nuchal ligament. Hence, it was considered an extra-nuchal fibroma. A description of key ultrasound and MRI imaging characteristics are provided to assist in making the diagnosis, along with a review of the current literature and a discussion of differential diagnoses.

Cryotherapy in extra-abdominal desmoid tumors: A systematic review and meta-analysis.

INTRODUCTION: Desmoid tumor is a locally-invasive neoplasm that causes significant morbidity. There is recent interest in cryotherapy for treatment of extra-abdominal desmoid tumors. This systematic review assesses evidence on safety and efficacy of cryotherapy in the treatment of extra-abdominal desmoid tumors. MATERIALS AND METHODS: The systematic review was conducted with reference to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Literature search was performed using MEDLINE and the Cochrane Central Register of Controlled Trials. 9 full text papers were reviewed and meta-analysis was performed for measures of safety, efficacy and symptom relief. RESULTS: The estimated pooled proportion of major and minor complications was 4.2% (95% CI, 1.8-9.6; I 2 = 0%) and 10.2% (95% CI, 5.7-17.8; I 2 = 0%) respectively. The estimated pooled proportion of non-progressive disease rate of all studies was 85.8% (95% CI, 73.4-93.0; I 2 = 32.9%). The estimated progression free survival rate at 1 year was 84.5% (95% CI:74.6-95.8) and 78.0% at 3 years (95% CI: 63.8-95.3). As for pain control, the estimated pooled proportion of patients with decrease in visual analogue scale (VAS) > = 3 for those with VAS > = 3 before treatment for 2 studies was 87.5% (95% CI, 0.06-100; I 2 = 71.5%) while 37.5% to 96.9% of patients were reported to have experienced partial or complete symptom relief in the other studies. CONCLUSION: Cryotherapy is a safe and effective treatment modality for extra-abdominal desmoid tumors with efficacy similar to those treated with traditional strategies in the short to medium term.

A Single-Center 10-Year Retrospective Analysis of Cryoablation for the Management of Desmoid Tumors.

PURPOSE: To determine the efficacy and safety of cryoablation in patients with desmoid tumors (DTs) retrospectively over a 10-year period at a single institution. MATERIALS AND METHODS: Between February 25, 2010, and February 25, 2020, 25 patients (age, 12-80 years) with 26 lesions (mean preprocedural tumor volume was 237 cm3) were treated over 44 cryoablation procedures. Eleven patients were treated with first-line therapy. Fourteen patients had previous medical therapy, radiotherapy, and/or surgery. Subsequent clinical follow-up, imaging outcomes, and safety were analyzed for technical success, change in total lesion volume (TLV) and viable tumor volume (VTV), modified response evaluation criteria in solid tumors (mRECIST), progression-free survival (PFS) for tumor progression and symptom recurrence, symptom improvement, and procedure-related complications. Symptomatic improvement was defined as documentation of relief of pain (partial or complete) and/or functional impairment. RESULTS: All procedures were technically successful. At 7-12 months, median changes in TLV and VTV were -6.7% (P = .809) and -43.7% (P = .01), respectively. At 10-12 months, the mRECIST responses were complete response, 0%; partial response, 61.5% (8/13); stable disease, 30.8% (4/13); and progressive disease, 7.7% (1/13). The median PFS for tumor progression and symptom recurrence were not reached, with a median follow-up of 15.3 and 21.0 months, respectively. Symptomatic relief (partial or complete) was achieved in 96.9% (32/33) of patients. One major complication was noted (2.4%). CONCLUSIONS: In this retrospectively identified cohort, cryoablation was effective and safe for the local control of extra-abdominal DTs in short-term follow-up.

Popping the cap: the constellation of MRI findings in patellofemoral syndrome.

Patellofemoral syndrome (PFS) is a common etiology of anterior knee pain, particularly among young female athletes. Despite recent advancements in the resolution of MRI, there still remains a paucity of literature that has investigated the MRI findings associated with PFS. This pictorial essay will describe our institution's experience with cases of PFS and review what we believe to be a constellation of findings associated with this diagnostic entity. This review will also describe common pitfalls encountered during the diagnosis of PFS.

Epiploic appendagitis: 7-year experience and relationship with visceral obesity.

PURPOSE: Location, size, and local inflammatory findings in primary epiploic appendagitis (EA) have not been reported outside of small studies. The association between EA and increased adiposity is controversial. The goals of this project are to compare demographics and imaging-based measurements of adiposity between patients with EA and patients with acute abdomen without EA, and to identify CT features of EA. METHODS: A consecutive sample of acute, primary EA (n = 100), and control (acute abdomen; n = 100) was selected retrospectively. Cases of suspected EA were included if they had the characteristic ovoid fatty mass and hyperattenuated ring sign on CT. Abdominal adipose volume (AAV), visceral adipose area (VAA), and subcutaneous adipose area (SAA) were quantified by CT. Location, size, and frequency of coexisting local inflammatory findings in EA patients were recorded. RESULTS: EA had 60% greater AAV, 117% greater VAA, and 35% greater SAA than control subjects (p < 0.0001). Males composed a great proportion of the EA group (67%) than the control group (41%) (p = 0.0002). Inflamed appendage was found in sigmoid colon in 49% of cases, descending colon in 23%, and right colon in 19%. Peritoneal thickening was frequent (76%) and bowel wall thickening was common (47%). Diverticulosis coexisted incidentally in 28%. CONCLUSION: EA is associated with increased abdominal adipose tissue. EA can occur in both sexes at any age, but occurs at age 50 on average and more frequently in males. Patient with EA exhibited central hyperdense dot (79%), peritoneal thickening (76%), and bowel wall thickening (47%).

The Hopeless Case? Palliative Cryoablation and Cementoplasty Procedures for Palliation of Large Pelvic Bone Metastases.

BACKGROUND: Metastases to the bone are common in cancer patients, and it has been estimated that up to 50% of patients with pelvic bone metastases will not achieve adequate pain control with medications alone. This has led to a paradigm shift over recent years towards the use and development of minimally invasive image-guided treatment options for palliation of bony metastases. Despite these developments, large metastatic lesions are still often considered to be "hopeless cases" that would garner little to no benefit from image-guided intervention. This study is the first large series to describe the novel use of combination percutaneous cryoablation and cementoplasty for palliation of such large metastases to the pelvis. OBJECTIVES: We aim to evaluate the efficacy and safety of image-guided percutaneous cryoablation and cementoplasty for palliation of large pelvic bone metastases. STUDY DESIGN: This retrospective analysis was approved by our institutional review board. This study was conducted from January 2013 to December 2016, where consecutive patients referred for pain management of large pelvic bone metastases underwent combination percutaneous cryoablation and cementoplasty. SETTING: This study took place at a tertiary care center after patients were referred following formal review from a multidisciplinary conference, which was comprised of interventional radiologists, pain management and palliative care physicians, radiation and medical oncologists, and when available, anesthesiologists. METHODS: Forty-eight patients (36 men and 12 women) with a mean cohort age of 77.5 years (range: 52 - 89 years) were referred from the multidisciplinary conference for palliation of pelvic bone metastases. The inclusion criteria included patients with metastases greater or equal to 5.0 cm and significant pain refractory to conventional pain management regimens. All of the patients were deemed not to be surgical candidates. Mean pain scores were collected at numerous time-points along with procedural technical success rates and complication rates. RESULTS: Combination cryoablation and cementoplasty was performed on 48 consecutively referred patients with a 100% technical success rate and no immediate complications. The pain levels demonstrated a significant decrease (P < 0.001) following intervention, with mean pain scores of 7.9 (range: 5 - 10) and 1.2 (range: 0 - 7) throughout the week prior to intervention and at 24 hours post-intervention, respectively. The post-intervention pain scores remained stable at 1 to 9 weeks follow-up (mean: 4.1 weeks). Three patents (6.3%) reported no change in pain following the intervention; however, no patients reported worsened pain. LIMITATIONS: The limitations of this study include its retrospective nature and the length of follow-up, which was often restricted given the life expectancy of our patient cohort. CONCLUSION: Combination cryoablation and cementoplasty is a novel and efficacious treatment option for palliation of large pelvic bone metastases. Marked improvements in pain, as well as mobility and quality of life, are often attainable. KEY WORDS: Pain, palliative care, palliation, percutaneous, cryoablation, cementoplasty, metastases, pelvis, interventional radiology, thermal ablation.

Detection of Bone Marrow Edema in Nondisplaced Hip Fractures: Utility of a Virtual Noncalcium Dual-Energy CT Application.

Purpose To quantify the sensitivity and specificity of dual-energy computed tomographic (CT) virtual noncalcium images in the detection of nondisplaced hip fractures and to assess whether obtaining these images as a complement to bone reconstructions alters sensitivity, specificity, or diagnostic confidence. Materials and Methods The clinical research ethics board approved chart review, and the requirement to obtain informed consent was waived. The authors retrospectively identified 118 patients who presented to a level 1 trauma center emergency department and who underwent dual-energy CT for suspicion of a nondisplaced traumatic hip fracture. Clinical follow-up was the standard of reference. Three radiologists interpreted virtual noncalcium images for traumatic bone marrow edema. Bone reconstructions for the same cases were interpreted alone and then with virtual noncalcium images. Diagnostic confidence was rated on a scale of 1 to 10. McNemar, Fleiss κ, and Wilcoxon signed-rank tests were used for statistical analysis. Results Twenty-two patients had nondisplaced hip fractures and 96 did not have hip fractures. Sensitivity with virtual noncalcium images was 77% and 91% (17 and 20 of 22 patients), and specificity was 92%-99% (89-95 of 96 patients). Sensitivity increased by 4%-5% over that with bone reconstruction images alone for two of the three readers when both bone reconstruction and virtual noncalcium images were used. Specificity remained unchanged (99% and 100%). Diagnostic confidence in the exclusion of fracture was improved with combined bone reconstruction and virtual noncalcium images (median score: 10, 9, and 10 for readers 1, 2, and 3, respectively) compared with bone reconstruction images alone (median score: 9, 8, and 9). Conclusion When used as a supplement to standard bone reconstructions, dual-energy CT virtual noncalcium images increased sensitivity for the detection of nondisplaced traumatic hip fractures and improved diagnostic confidence in the exclusion of these fractures. © RSNA, 2017 Online supplemental material is available for this article. An earlier incorrect version of this article appeared online. This article was corrected on March 17, 2017.

Dual-Energy CT for the Musculoskeletal System.

The principal advantages of dual-energy computed tomography (CT) over conventional CT in the musculoskeletal setting relate to the additional information provided regarding tissue composition, artifact reduction, and image optimization. This article discusses the manifestations of these in clinical practice-urate and bone marrow edema detection, metal artifact reduction, and tendon analysis, with potential in arthrography, bone densitometry, and metastases surveillance. The basic principles of dual-energy CT physics and scanner design will also be discussed. © RSNA, 2016.

Getting the Most From Your Dual-Energy Scanner: Recognizing, Reducing, and Eliminating Artifacts.

OBJECTIVE: Dual-energy CT (DECT) is an innovative imaging modality that allows superior detection of pulmonary embolism, enhanced detection of urate in gout, and improved assessment of metal prostheses when compared with conventional CT. CONCLUSION: The primary aim of this review is to describe these DECT protocols and compare each to its respective diagnostic reference standards. Moreover, this review will describe how to recognize, reduce, and eliminate DECT artifacts, thereby maximizing its diagnostic capabilities.

Imaging of limb salvage surgery and pelvic reconstruction following resection of malignant bone tumours.

Advances in reconstructive orthopaedic techniques now allow for limb salvage and prosthetic reconstruction procedures to be performed on patients who would otherwise be required to undergo debilitating limb amputations for malignant bone tumours. The resulting post-operative imaging of such cases can be daunting for the radiologist to interpret, particularly in the presence of distorted anatomy and unfamiliar hardware. This article reviews the indications for limb salvage surgery, prosthetic reconstruction devices involved, expected post-operative imaging findings, as well as the potential hardware related complications that may be encountered in the management of such cases.

Dual-energy computed tomographic virtual noncalcium algorithm for detection of bone marrow edema in acute fractures: early experiences.

Computed tomography (CT) is often used to assess the presence of occult fractures when plain radiographs are equivocal in the acute traumatic setting. While providing increased spatial resolution, conventional computed tomography is limited in the assessment of bone marrow edema, a finding that is readily detectable on magnetic resonance imaging (MRI).Dual-energy CT has recently been shown to demonstrate patterns of bone marrow edema similar to corresponding MRI studies. Dual-energy CT may therefore provide a convenient modality for further characterizing acute bony injury when MRI is not readily available. We report our initial experiences of 4 cases with imaging and clinical correlation.