Multienergy Computed Tomography Applications: Trauma.

Computed tomography (CT) plays an important role in trauma because imaging findings directly impact management. Advances in CT technology, specifically multienergy CT, have allowed for simultaneous acquisition of images at low and high kilovolt peaks. This technique allows for differentiation of materials given that materials have different absorption behaviors. Various multienergy CT postprocessing applications are helpful in the setting of trauma, including bone subtraction, virtual monoenergetic imaging, iodine-selective imaging, and virtual noncontrast imaging. These techniques have been applied from head to toe and have been used to improve image quality and increase conspicuity of injuries, which increases diagnostic confidence.

Imaging features of toxicities associated with immune checkpoint inhibitors.

The past decade has witnessed a change in landscape of cancer management with the advent of precision oncology. Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment and have played an important role in improving patient survival. While the patients are living longer, treatment with ICIs are sometimes associated with adverse effects, some of which could be fatal. Radiologists can play a crucial role by early identification of some of these adverse effects during restaging scans. Our paper focuses on the imaging features of commonly occurring ICI toxicities based on organ system.

CT imaging findings of complications of optical colonoscopy.

Colonoscopy is one of the most commonly performed endoscopic procedures and remains the most commonly used screening modality method for colorectal cancer (CRC) screening in the USA. Although serious complications of fiberoptic colonoscopy are uncommon due to technical advances, due to increasing number of colonoscopy procedures, post-procedural complications are not uncommonly encountered in the routine clinical practice. Also, as some of the post-colonoscopy complications are life threatening, it is important to diagnose them early so that timely treatment measures can be taken to decrease mortality and morbidity. In this review, we present a case-based illustration of the utility of CT to detect complications of colonoscopy including bowel perforation, hemorrhage, splenic injury, and postpolypectomy syndrome.

Clinical significance of "positive" cervical spine MRI findings following a negative CT.

PURPOSE: To review and analyze the clinical significance of positive acute traumatic findings seen on MRI of the cervical spine (MRCS) following a negative CT of the cervical spine (CTCS) for trauma. METHODS: We performed a sub-cohort analysis of 54 patients with negative CTCS and a positive MRCS after spine trauma from the previous multicenter study of the Research Consortium of New England Centers for Trauma (ReCONECT). Both CTCS and MRCS were independently reviewed by two emergency radiologists and two spine surgeons. The surgeons also commented on the clinical significance of the traumatic findings seen on MRCS and grouped them into unstable, potentially unstable, and stable injuries. RESULTS: Among 35 unevaluable patients, MRCS showed one unstable (hyperextension) and two potentially unstable (hyperflexion) injuries. Subtle findings were seen on CTCS in 2 of 3 patients upon careful retrospective review that would have suggested these injuries. Of 19 patients presenting with cervicalgia, 2/5 (40%) patients with neurological deficit demonstrated clinically significant findings on MRCS with predisposing factors seen on CT. None of the 14 patients with isolated cervicalgia and no neurological deficit had clinically significant findings on their MRCS. CONCLUSION: While CTCS is adequate for clearing the cervical spine in patients with isolated cervicalgia, MRCS can play a critical role in patients with neurological deficits and normal CTCS. Clinically significant traumatic findings were seen in 8.5% of unevaluable patients on MRCS, though these injuries in fact could be identified on the CT in 2 of 3 patients upon careful retrospective review.

Recognizing Isolated Ulnar Fractures as Potential Markers for Intimate Partner Violence.

PURPOSE: This study aimed to assess the incidence of intimate partner violence (IPV) in women with isolated ulnar fractures and compare the injury characteristics in victims of IPV with those who sustained the same fractures due to other causes. METHODS: Electronic health records from three level I trauma centers were queried to identify a cohort of women, aged 18 to 50, sustaining isolated ulnar fractures from 2005 to 2019. Radiographs were reviewed for fracture location, comminution, and displacement. Demographic data, number of visits to the emergency department, and documentation of IPV were also collected. Patients were stratified into four groups based on clinical chart review: confirmed IPV, possible IPV, not suspected for IPV, and not IPV. Historical imaging analysis for IPV prediction was also performed. RESULTS: There were 62 patients, with a mean age of 31 years (IPV: 12 confirmed, 8 possible, 8 suspected not IPV, 34 confirmed not IPV). Comparative analysis with and without suspected cases demonstrated IPV to be associated with nondisplaced fractures (95% versus 43%; P < .001 and 91% versus 44%; P = .012). Confirmed cases were also associated with homelessness (46% versus 0%; P < .001), and the number of documented emergency department visits (median 7.0; interquartile range 2.0-12.8 versus 1.0; interquartile range 1.0-2.0; P < .001). Formal documentation of IPV evaluation was completed in only 14 of 62 (22.5%) patients. Historical imaging analysis predicted IPV in 8 of 12 (75%) confirmed IPV cases. CONCLUSION: Up to one-third of adult women sustaining isolated ulnar fractures may be the victims of IPV. Lack of displacement on radiographs, frequent emergency department visits, and homelessness would favor IPV etiology.

Spinal trauma in DISH and AS: is MRI essential following the detection of vertebral fractures on CT?

BACKGROUND: Both ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) cause a rigid spine, but through different pathophysiology. Recent data has shown that characteristic fracture patterns may also differ following trauma since the posterior osseous and soft tissue elements are often spared in DISH. CT and MRI are important in diagnosing spine injury, but given the differences between AS and DISH, the utility of obtaining both studies in all patients warrants scrutiny. PURPOSE: To assess the prevalence of posterior element injury on CT and MRI in DISH and AS patients with known vertebral body injury detected on CT; to determine whether MRI demonstrates additional injuries in neurologically intact patients presumed to have isolated vertebral body injuries on CT. STUDY DESIGN: Multicenter, retrospective, case-control study. PATIENT SAMPLE: DISH and AS patients presenting after spine trauma between 2007 and 2017. OUTCOME MEASURES: Review of CT and MRI findings at the time of presentation. METHODS: One hundred sixty DISH and 85 AS patients presenting after spine trauma were identified from 2 affiliated academic hospitals serving as level 1 trauma and tertiary referral centers. A diagnosis of DISH or AS was verified by a board-certified emergency radiologist with 3 years of experience. Age, gender, mechanism of injury, fracture type, spine CT and MRI imaging findings, surgical intervention, and neurologic deficit were recorded. The CT and MRI studies were reviewed by the same radiologist for fracture location and type using the AO spine classification. No funding source or conflict of interest was present. RESULTS: Median age was 72 and 79 years old for the AS and DISH groups, respectively. Both were predominantly male (81%) and most presented after a low energy mechanism of injury (74% and 73%). Type C AO spine injuries were seen in 52% of AS patients but only 4% of DISH patients. In patients with known vertebral body injury on CT, additional injury to the posterior elements on CT or MRI in DISH patients was 51% versus 92% in AS patients. However, in patients with an isolated vertebral body fracture on CT and no neurological deficit, MRI identified posterior element injury in only 4/22 (18%) DISH patients compared to 5 of 7 (71%) AS patients. None of the MRI findings in the DISH patients were considered clinically important while all 5 AS patients eventually underwent operative treatment despite having no neurological deficit. Epidural hematoma on MRI was seen in 43% of AS patients as opposed to 5% of DISH patients. CONCLUSION: Based on our small sample size, CT alone may be adequate in DISH patients with isolated vertebral body fractures and no neurologic deficit, but an additional MRI should be considered in the presence of an unclear neurological exam or deficit. MRI should be strongly considered for any AS patient regardless of neurologic status.

Dual energy CT in clinical routine: how it works and how it adds value.

Dual energy computed tomography (DECT), also known as spectral CT, refers to advanced CT technology that separately acquires high and low energy X-ray data to enable material characterization applications for substances that exhibit different energy-dependent x-ray absorption behavior. DECT supports a variety of post-processing applications that add value in routine clinical CT imaging, including material selective and virtual non-contrast images using two- and three-material decomposition algorithms, virtual monoenergetic imaging, and other material characterization techniques. Following a review of acquisition and post-processing techniques, we present a case-based approach to highlight the added value of DECT in common clinical scenarios. These scenarios include improved lesion detection, improved lesion characterization, improved ease of interpretation, improved prognostication, inherently more robust imaging protocols to account for unexpected pathology or suboptimal contrast opacification, length of stay reduction, reduced utilization by avoiding unnecessary follow-up examinations, and radiation dose reduction. A brief discussion of post-processing workflow approaches, challenges, and solutions is also included.

Intimate Partner Violence: A Primer for Radiologists to Make the "Invisible" Visible.

Intimate partner violence (IPV) is the physical, sexual, or emotional violence between current or former partners. It is a major public health issue that affects nearly one out of four women. Nonetheless, IPV is greatly underdiagnosed. Imaging has played a significant role in identifying cases of nonaccidental trauma in children, and similarly, it has the potential to enable the identification of injuries resulting from IPV. Radiologists have early access to the radiologic history of such victims and may be the first to diagnose IPV on the basis of the distribution and imaging appearance of the patient's currrent and past injuries. Radiologists must be familiar with the imaging findings that are suggestive of injuries resulting from IPV. Special attention should be given to cases in which there are multiple visits for injury care; coexistent fractures at different stages of healing, which may help differentiate injuries related to IPV from those caused by a stranger; and injuries in defensive locations and target areas such as the face and upper extremities. The authors provide an overview of current methods for diagnosing IPV and define the role of the radiologist in cases of IPV. They also describe a successful diagnostic imaging-based approach for helping to identify IPV, with a specific focus on the associated imaging findings and mechanisms of injuries. In addition, current needs and future perspectives for improving the diagnosis of this hidden epidemic are identified. This information is intended to raise awareness among radiologists, with the ultimate goal of improving the diagnosis of IPV and thus reducing the devastating effects on victims' lives. ©RSNA, 2020.

Association between Nonalcoholic Fatty Liver Disease at CT and Coronary Microvascular Dysfunction at Myocardial Perfusion PET/CT.

Background Cardiovascular disease is a major cause of mortality in patients with nonalcoholic fatty liver disease (NAFLD). However, the association of NAFLD with coronary microvascular dysfunction is, to our knowledge, unknown. Purpose To determine whether coronary microvascular dysfunction is more prevalent in patients with NAFLD and to determine whether coronary microvascular dysfunction predicts major adverse cardiac events (MACE) independently of NAFLD. Materials and Methods This retrospective study (2006-2014) included patients without evidence of obstructive epicardial coronary artery disease and healthy left ventricular ejection fraction (≥40%) at a clinical rest and stress myocardial perfusion PET/CT. NAFLD was defined by a mean hepatic attenuation of less than 40 HU at CT and coronary microvascular dysfunction as a coronary flow reserve (CFR) of less than 2.0. A composite of all-cause mortality, myocardial infarction, coronary revascularization, and hospitalization because of heart failure comprised MACE (130 of 886 patients; 14.7%). The relation between NAFLD and MACE was assessed by using multivariable Cox regression analysis. Results Among 886 patients (mean age, 62 years ± 12 [standard deviation]; 631 women [mean age, 62 years ± 12 years] and 255 men [mean age, 61 years ± 12]; and ejection fraction, 63% ± 9), 125 patients (14.1%) had NAFLD and 411 patients (46.4%) had coronary microvascular dysfunction. Coronary microvascular dysfunction was more prevalent (64.8% vs 43.4%; P < .001) and CFR was lower (1.9 ± 1.1 vs 2.2 ± 0.7; P < .001) in patients with NAFLD compared with those without NAFLD. NAFLD independently predicted coronary microvascular dysfunction (P = .01). The interaction of NAFLD and male sex predicted MACE (hazard ratio, 1.45; 95% confidence interval: 1.08, 1.69; P = .008) and coronary microvascular dysfunction remained associated with MACE (adjusted hazard ratio, 1.46; 95% confidence interval: 1.02, 2.07; P = .04). Conclusion Coronary microvascular dysfunction was more prevalent in patients with nonalcoholic fatty liver disease and predicted major adverse cardiac events independently of nonalcoholic fatty liver disease. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Ambale-Venkatesh and Lima in this issue.

Injuries to the Rigid Spine: What the Spine Surgeon Wants to Know.

The biomechanical stability of the spine is altered in patients with a rigid spine, rendering it vulnerable to fracture even from relatively minor impact. The rigid spine entities are ankylosing spondylitis (AS), diffuse idiopathic skeletal hyperostosis, degenerative spondylosis, and a surgically fused spine. The most common mechanism of injury resulting in fracture is hyperextension, which often leads to unstable injury in patients with a rigid spine per the recent AOSpine classification system. Due to the increased risk of spinal fractures in this population, performing a spine CT is the first step when a patient with a rigid spine presents with new back pain or suspected spinal trauma. In addition, there should be a low threshold for performing a non-contrast-enhanced spine MRI in patients with a rigid spine, especially those with AS who may have an occult fracture, epidural hematoma, or spinal cord injury. Unfortunately, owing to insufficient imaging and an unfamiliarity with fracture patterns in the setting of a rigid spine, fracture diagnosis is often delayed, leading to significant morbidity and even death. The radiologist's role is to recognize the imaging features of a rigid spine, identify any fractures at CT and MRI, and fully characterize the extent of injury. Reasons for surgical intervention include neurologic deficit or concern for deterioration, an unstable fracture, or the presence of an epidural hematoma. By understanding the imaging features of various rigid spine conditions and vigilantly examining images for occult fractures, the radiologist can avoid a missed or delayed diagnosis of an injured rigid spine. ©RSNA, 2019.

Pneumatosis Intestinalis After Molecular-Targeted Therapy.

BACKGROUND: Pneumoperitoneum after surgical manipulation of the abdomen implies a perforation. Rare cases of nonoperated cancer patients, largely with gastrointestinal or genitourinary cancers, have been noted to have radiologic findings of pneumatosis intestinalis and/or pneumoperitoneum as a complication of molecular-targeted therapy (MTT) without confounding factors for perforation. We present a patient with a cranial malignancy treated with bevacizumab who subsequently manifested with pneumatosis intestinalis. CASE DESCRIPTION: A 67-year-old man with metastatic melanoma, non-small cell lung cancer, and recurrent cerebellar subependymoma was initiated on bevacizumab treatment for subependymoma recurrence. He subsequently underwent an uncomplicated ventriculoperitoneal shunt for progressive obstructive hydrocephalus, confirmed by a normal postoperative abdominal radiograph. One week later, he returned with worsening lethargy and a computed tomography consistent with pneumomediastinum and pneumoperitoneum. Due to concern for bowel perforation, the patient underwent diagnostic laparoscopy and removal of ventriculoperitoneal shunt. Focal sigmoid pneumatosis was identified without any signs of bowel perforation or ischemia. Bevacizumab was discontinued, and the patient's radiologic and clinical findings improved. CONCLUSIONS: With increasing utilization of MTTs in brain tumor management, we raise MTT as a potential cause for pneumoperitoneum in neurosurgical patients. Pneumoperitoneum after extracranial procedures still requires workup and management for potential bowel perforation, but alternative causes such as bevacizumab should also be considered. Pneumatosis intestinalis patients on MTT can have benign physical examinations and will resolve, in the majority of cases, on discontinuation of the drug.

Quantification of radiation dose reduction by reducing z-axis coverage in 320-detector coronary CT angiography.

OBJECTIVE: To quantify the radiation dose reduction achievable by minimizing z-axis coverage in 320-detector coronary CT angiography (CCTA). METHODS: We retrospectively reviewed 130 CCTAs performed on 320-detector CT that offers up to 16 cm z-axis coverage (adjustable in 2-cm increments), allowing complete coverage of the heart in a single gantry rotation. For each CT, we obtained the radiation dose [CT dose index and dose-length product (DLP)], measured the z-axis field of view and measured the craniocaudal cardiac size (distance from the left main coronary artery to the cardiac apex). We calculated the radiation dose savings achievable by reducing the z-axis coverage to the minimum necessary to cover the heart using 320 × 0.5-mm (maximum 16 cm) and 256 × 0.5-mm (maximum 12.8 cm) detector collimations. RESULTS: Results are expressed as mean ± standard deviation. The mean craniocaudal cardiac size was 10.5 ± 1.0 cm, with 85% (n = 112) of CCTAs performed with 16 cm of z-axis coverage. The mean DLP was 417.6 ± 182.4 mGy cm, with the mean DLP saving achievable using the minimum z-axis coverage required to completely image the heart being 96.2 ± 47.4 mGy cm, an average dose reduction of 26.9 ± 7.0%. z-axis coverage of ≤12 cm was adequate for 92% and 12.8 cm for 98% of subjects. CONCLUSION: Using the minimal z-axis coverage to adequately image the heart is a simple step that can reduce the DLP in 320-detector CCTA by approximately 27%. z-axis coverage of ≤12 cm is adequate for 92%, 12.8 cm for 98% and 14 cm for 100% of patients undergoing CCTA. Advances in knowledge: Reducing z-axis coverage in 320-detector CCTA can reduce DLP by approximately 27%.

Differences in the imaging features and distribution of non-indolent and indolent mastocytosis: a single institution experience of 29 patients.

PURPOSE: Compare imaging features of indolent and non-indolent mastocytosis. METHODS: For 29 patients, imaging features, imaging indications, and distribution of indolent and non-indolent mastocytosis subtypes were analyzed. RESULTS: 16/29 (55%) patients had three distinct patterns of osseous abnormality, not significantly differing between cohorts. Non-indolent disease was more likely to present with hepatomegaly (p=0.0004), splenomegaly (p=0.0097), and lymphadenopathy (p=0.0079). CT, was the most common initial imaging modality, ordered to stage disease in 20 of 29 patients (69%). CONCLUSION: Understanding patterns of involvement of indolent and nonindolent mastocytosis across modalities could assist radiologists in evaluating mastocytosis.

Diffuse Large B-Cell Lymphoma in the Era of Precision Oncology: How Imaging Is Helpful.

Diffuse large B cell lymphoma (DLBCL) is the most common histological subtype of Non-Hodgkin's lymphoma. As treatments continues to evolve, so do imaging strategies, and positron emission tomography (PET) has emerged as the most important imaging tool to guide oncologists in the diagnosis, staging, response assessment, relapse/recurrence detection,and therapeutic decision making of DLBCL. Other imaging modalities including magnetic resonance imaging (MRI), computed tomography (CT), ultrasound, and conventional radiography are also used in the evaluation of lymphoma. MRI is useful for nervous system and musculoskeletal system involvement and is emerging as a radiation free alternative to PET/CT. This article provides a comprehensive review of both the functional and morphological imaging modalities, available in the management of DLBCL.

Metastatic Patterns of Solitary Fibrous Tumors: A Single-Institution Experience.

OBJECTIVE: The objective of our study was to evaluate the metastatic patterns and imaging features of solitary fibrous tumors (SFTs). MATERIALS AND METHODS: This retrospective study included 139 patients with pathologically proven SFT, 49 of whom developed metastases. Electronic medical records and all available images were reviewed to record the pattern and imaging appearances of metastatic disease, and comparisons of thoracic SFTs and extrathoracic SFTs were also performed. Associations of metastatic spread were studied using univariate and multivariate Cox regression analyses. RESULTS: A total of 49 (35%) patients developed metastases at a median of 124 months (interquartile range [IQR], 66-195 months) after SFT diagnosis; 11 patients (8%) had metastases at presentation. Of these 49 patients, 40 patients died at a mean of 183 months after diagnosis. The associations with metastatic disease on univariate analysis were tumor size ≥ 10 cm (p = 0.01) and malignant pathology or mitotic count ≥ 4 per 10 high-power fields (HPF) (p < 0.001). Malignant pathology and a mitotic count of ≥ 4 per 10 HPF were also associated with metastatic disease on multivariate analysis (p = 0.01; hazard ratio, 0.22; 95% CI, 0.05-0.73). The most common sites of metastasis were the lungs (30/49, 61%) followed by the pleura (24/49, 49%) and then the liver (20/49, 41%), bones (20/49, 41%), and peritoneum (20/49, 41%). A significantly higher proportion of patients with extrathoracic SFT had metastatic disease (37/139, 27%) compared with those with thoracic SFT (12/139, 9%) (p = 0.003). The overall metastasis-free survival was a median of 117 months (IQR, 33-169 months) in patients with extrathoracic SFT and a median of 120 months (IQR, 82-169 months) in patients with thoracic SFT (p = 0.01). CONCLUSION: A mitotic count of ≥ 4 per 10 HPF or malignant pathology was significantly associated with metastatic disease on both univariate and multivariate analyses. The sites of metastatic disease differed depending on the site of the primary SFT but were most commonly the lung and pleura. Patients with extrathoracic SFT were statistically more likely to develop metastatic disease than those with thoracic SFT.

Current Concepts in the Molecular Genetics and Management of Thyroid Cancer: An Update for Radiologists.

Substantial improvement in the understanding of the oncogenic pathways in thyroid cancer has led to identification of specific molecular alterations, including mutations of BRAF and RET in papillary thyroid cancer, mutation of RAS and rearrangement of PPARG in follicular thyroid cancer, mutation of RET in medullary thyroid cancer, and mutations of TP53 and in the phosphatidylinositol 3'-kinase (PI3K)/AKT1 pathway in anaplastic thyroid cancer. Ultrasonography (US) and US-guided biopsy remain cornerstones in the initial workup of thyroid cancer. Surgery is the mainstay of treatment, with radioactive iodine (RAI) therapy reserved for differentiated subtypes. Posttreatment surveillance of thyroid cancer is done with US of the thyroid bed as well as monitoring of tumor markers such as serum thyroglobulin and serum calcitonin. Computed tomography (CT), magnetic resonance imaging, and fluorine 18 fluorodeoxyglucose positron emission tomography/CT are used in the follow-up of patients with negative iodine 131 imaging and elevated tumor markers. Certain mutations, such as mutations of BRAF in papillary thyroid carcinoma and mutations in RET codons 883, 918, and 928, are associated with an aggressive course in medullary thyroid carcinoma, and affected patients need close surveillance. Treatment options for metastatic RAI-refractory thyroid cancer are limited. Currently, Food and Drug Administration-approved molecularly targeted therapies for metastatic RAI-refractory thyroid cancer, including sorafenib, lenvatinib, vandetanib, and cabozantinib, target the vascular endothelial growth factor receptor and RET kinases. Imaging plays an important role in assessment of response to these therapies, which can be atypical owing to antiangiogenic effects. A wide spectrum of toxic effects is associated with the molecularly targeted therapies used in thyroid cancer and can be detected at restaging scans. (©)RSNA, 2016.

MRI Findings in Patients With Leukemia and Positive CSF Cytology: A Single-Institution 5-Year Experience.

OBJECTIVE: The purposes of this study were to describe the spectrum of MRI findings and determine the prognostic role of MRI in adults with acute leukemia with positive CSF cytology. MATERIALS AND METHODS: In this retrospective study of 34 patients (19 women, 15 men; mean age, 51 years; range, 18-72 years) treated for CNS leukemia between 2006 and 2011, 31 (91%) contrast-enhanced brain and 14 (41%) spine MRI studies were reviewed by two radiologists to note patterns of enhancement. Interobserver agreement and correlation of enhancement with outcome were analyzed. RESULTS: MRI showed abnormal findings in 25 patients (74%). Pachymeningeal enhancement (n = 9/31, 29%), leptomeningeal enhancement (n = 6/31, 19%), cranial nerve enhancement (n = 9/31, 29%), masslike enhancement (n = 3/31, 10%), and spinal meningeal enhancement (n = 10/14, 71%) were identified. There was strong interobserver agreement (κ = 0.906). Survival rates were shorter to a statistically significant degree with pachymeningeal enhancement (median, 7 months; interquartile range [IQR], 5-8 months versus median, 26 months; IQR, 15 months to not reached; p = 0.004) and two or more sites of enhancement (median, 8 months; IQR, 3-13 months versus median, 19 months; IQR, 9 months to not reached; p = 0.046). CONCLUSION: Brain or spine MRI examinations (or both) showed abnormal findings in nearly three-fourths of adults with acute leukemia with positive CSF cytology who were imaged for neurologic symptoms. Pachymeningeal enhancement and two or more sites of brain involvement were associated with shorter survival.