Variation in Fetal Weight Percentile Estimates.

OBJECTIVES: Weight percentiles are generally reported without any indication of error. This variation can lead a fetus being mistakenly classified erroneously as having intrauterine growth restriction (IUGR) or macrosomia. The goal of this study was to compare estimated weight percentiles with the actual observed weight percentile for each gestational age in a large cohort of fetuses being scanned in our institution. METHODS: After IRB approval the radiology information system data base was retrospectively searched for all obstetrical US reports obtained during the late second and third trimesters from July 1, 2014, until July 1, 2020. Demographic information, fetal weight, and weight percentile information were obtained from these reports. Quantile-quantile plots were created for all gestational ages and all ethnicities. RESULTS: Our study included 6259 ultrasounds in 4060 patients. Mean maternal age of the total group was 31.68 years (ranging 15-53 years). When all subjects were considered, the median values in our QQ plots approximated the line of identity. However, there was considerable variation for a given estimate, implying that estimated fetal weight percentiles are only very rough predictors of the actual percentile. CONCLUSION: Estimated fetal weight percentiles are only very rough predictors of the actual percentile. We therefore suggest that estimates of the weight percentile should be reported along with an estimate of the expected variation. Recognition of variations in weight percentile should be considered in the greater clinical context, and could potentially prevent misdiagnosis of growth restriction and macrosomia as well as the subsequent overutilization of resources, unnecessary interventions, and maternal stress.

Immunogenicity of a rheumatoid arthritis protective sequence when acquired through microchimerism.

HLA class II genes provide the strongest genetic contribution to rheumatoid arthritis (RA). HLA-DRB1 alleles encoding the sequence DERAA are RA-protective. Paradoxically, RA risk is increased in women with DERAA+ children born prior to onset. We developed a sensitive qPCR assay specific for DERAA, and found 53% of DERAA-/- women with RA had microchimerism (Mc; pregnancy-derived allogeneic cells) carrying DERAA (DERAA-Mc) vs. 6% of healthy women. DERAA-Mc quantities correlated with an RA-risk genetic background including DERAA-binding HLA-DQ alleles, early RA onset, and aspects of RA severity. CD4+ T cells showed stronger response against DERAA+ vs. DERAA- allogeneic cell lines in vitro, in line with an immunogenic role of allogeneic DERAA. Results indicate a model where DERAA-Mc activates DERAA-directed T cells that are naturally present in DERAA-/- individuals and can have cross-reactivity against joint antigens. Moreover, we provide an explanation for the enigmatic observation that the same HLA sequence differentially affects RA risk through Mendelian inheritance vs. microchimeric cell acquisition.

Exophytic External Occipital Protuberance Prevalence Pre- and Post-iPhone Introduction: A Retrospective Cohort.

Introduction: In controversial fashion, the presence of an enlarged external occipital protuberance has been recently linked to excessive use of handheld electronic devices. We sought to determine the prevalence of this protuberance in a diverse age group of adults from two separate time periods, before and approximately 10 years after the release of the iPhone, to further characterize this theory, as if indeed valid, such a relationship could direct preventative behavior. Materials and Methods: Eighty-two cervical spine radiographs between March 7, 2007 through June 29, 2007 and 147 cervical spine radiographs between October 25, 2017 through January 1, 2018 were reviewed for the presence or absence of an exophytic external occipital protuberance. Influence of sex and age were also assessed. Results: There were 41/82 (50%) patients within the 2007 pre-iPhone group with an exophytic external occipital protuberance, ranging from 2.7-33.8 mm in length. Twenty-seven out of 82 (32.9%) had an external occipital protuberance at or above 10 mm. There were 49/147 (33.3%) patients within the 2017 post-iPhone group with an exophytic external occipital protuberance, ranging from 4.4-53.8 mm in length. Thirty-three out of 147 (22.4%) had an external occipital protuberance at or above 10 mm. When considering accessibility to the iPhone, sex, and age to the presence of an exophytic external occipital protuberance, only sex has a statistically significant association, p=0.000000033. Conclusion: We found no significant association with iPhone accessibility and an exophytic external occipital protuberance. Due to inherent limitations in the retrospective nature of the study, future research is needed to better examine the association of handheld electronic devices with exophytic external occipital protuberances.

The Relevance of Ulnar-Sided Contrast Extravasation During Radiocarpal Joint Wrist Arthrography.

OBJECTIVE: Contrast material often extends from the radiocarpal joint into the proximal soft tissues adjacent to the ulnar aspect of the ulnar styloid during single-compartment radiocarpal joint MR arthrography of the wrist. The hypothesis of this study was that this is a common finding unrelated to symptoms or examination technique. MATERIALS AND METHODS: Wrist MR arthrograms were retrospectively reviewed in consensus by two radiologists. The presence or absence of ulnar-sided contrast extravasation was documented, whether this extravasation appeared contained or dispersed, as was the overall degree of proximal extension of the extravasated contrast material. Patient age, sex, wrist sidedness, volume of contrast material administered, location of symptoms reported clinically, and aberrant contrast material also apparent within the midcarpal space or distal radioulnar joint on the MR images reviewed were documented to determine potential association with ulnar-sided contrast extravasation. RESULTS: Ninety-nine examinations met the inclusion criteria. Ulnar-sided contrast extravasation after single-compartment radiocarpal joint injection was present in 56 of the 99 wrists (57%). This finding was statistically more common in right versus left wrists. No other statistically significant associations were identified. CONCLUSION: Contrast extravasation along the ulnar aspect of the distal ulna after single-compartment radiocarpal joint injection is common. In this study it had no statistically significant association with the location of a patient's wrist pain or abnormal findings evaluated at MR arthrography.

Some new angles on the magic angle: what MSK radiologists know and don't know about this phenomenon.

PURPOSE: Magic angle effects (MAE) are well-recognized in musculoskeletal (MSK) MRI. With short TE acquisitions, the signal intensity of tendons, ligaments, and menisci depend on their orientation relative to the main magnetic field (B0). An interactive resident physics teaching module simulating MR imaging of a tendon forced us to identify and correct several misconceptions we had about MAE. We suspected these misconceptions were shared by other MSK radiologists. MATERIALS AND METHODS: We surveyed members of the Society of Academic Bone Radiologists (SABR) regarding which pulse sequences, acquisition parameters, tissues and angles relative to B0 were most likely to produce MAE. RESULTS: Survey respondents knew that MAE strongly depend on TE and commonly appear on T1W, FSE and PD sequences, but were less aware that MAE may also appear on T2W, STIR and DWI sequences. They knew of MAE effects in tendons, ligaments and cartilage, but were less aware of those in entheses, peripheral nerves and intervertebral discs. Respondents underestimated the wide angular range (full-width at half-maximum ≈ 40∘) over which significant MAE can be seen with short TE. CONCLUSIONS: Collagen-containing tissues with parallel molecular alignment exhibit increased signal intensity when oriented at 55∘ relative to B0. Experienced MSK radiologists were found to underestimate the combinations of image parameters, pulse sequences, tissues and collagen orientations in which significant MAE may be seen. Our survey results highlight the need for ongoing MR physics education for practicing radiologists.

Pathologies of the shoulder and elbow affecting the overhead throwing athlete.

The overhead-throwing athlete is susceptible to a variety of predictable disease entities affecting the shoulder and elbow. While the pathophysiology and nomenclature of these diseases are ubiquitous throughout the clinical literature, this information is sparse within the radiology domain. We provide a comprehensive review of these unique injuries with accompanying imaging features in an effort to enhance the role of the radiologist during the management of the overhead thrower. When appropriately recognized and described, the imaging features aid in establishing a diagnosis and ultimately the implementation of appropriate clinical management.

The Zombie Plot: A Simple Graphic Method for Visualizing the Efficacy of a Diagnostic Test.

OBJECTIVE: One of the most important jobs of a radiologist is to pick the most appropriate imaging test for a particular clinical situation. Making a proper selection sometimes requires statistical analysis. The objective of this article is to introduce a simple graphic technique, an ROC plot that has been divided into zones of mostly bad imaging efficacy (ZOMBIE, hereafter referred to as the "zombie plot"), that transforms information about imaging efficacy from the numeric domain into the visual domain. CONCLUSION: The numeric rationale for the use of zombie plots is given, as are several examples of the clinical use of these plots. Two online calculators are described that simplify the process of producing a zombie plot.

CT and MR Imaging of the Postoperative Ankle and Foot.

A variety of surgical procedures exist for repair of both traumatic and degenerative osseous and soft-tissue pathologic conditions involving the foot and ankle. It is necessary for the radiologist to be familiar with these surgical procedures, so as to assess structural integrity, evaluate for complicating features, and avoid diagnostic pitfalls. Adequate interpretation of postoperative changes often requires access to surgical documentation to evaluate not only the surgery itself but the expected timeline for resolution of normal postoperative changes versus progressive disease. Appropriate use of surgical language in radiology reports is another important skill set to hone and is instrumental in providing a high-quality report to the referring surgeons. The pathophysiology of a myriad of surgical complaints, beginning from the Achilles tendon and concluding at the plantar plate, are presented, as are their common appearances at computed tomography and magnetic resonance imaging. Commonly encountered entities include Achilles tendon tear, spastic equinus, nonspastic equinus, talar dome osteochondral defect, tarsal tunnel syndrome, plantar fasciitis, pes planovalgus, pes cavovarus, peroneal tendinosis, lateral ligament complex pathology, Morton neuroma, plantar plate tear, and metatarsophalangeal joint instability. Computer-generated three-dimensional models are included with many of the procedures to provide a more global view of the surgical anatomy. Correlation with intraoperative photographs is made when available. When appropriate, discussion of postoperative complications, including entities such as infection and failure of graft integration, is presented, although a comprehensive review of postoperative complications is beyond the scope of this article. Notably absent from the current review are some common foot and ankle procedures including hallux valgus and hammertoe corrections, as these are more often evaluated radiographically than with cross-sectional imaging. ©RSNA, 2016.

Case 215: voriconazole-induced periostitis.

History A 74-year-old woman presented with multifocal bone pain, including pain in multiple ribs, bilateral shoulders, and bilateral hips. The pain began several months before presentation and was quite severe, ultimately necessitating control with narcotics. At examination, strength in both lower extremities was slightly reduced, sensation and reflexes were intact, and range of motion was full, though painful. There were no notable constitutional symptoms of fever or weight loss. Laboratory work-up was remarkable for elevated alkaline phosphatase level (277 U/L [4.6 mkat/L]). The patient had undergone left lung transplantation 8 years prior for pulmonary fibrosis. A thorough pulmonary work-up for the cause of fibrosis, which included gathering an exposure, occupational, allergy, and previous infectious history, and a rheumatoid work-up were negative. The patient's posttransplantation course was complicated by bronchiolitis obliterans from chronic rejection and by recent pulmonary embolism, for which she was undergoing anticoagulation therapy at the time of presentation. Additionally, the patient experienced repeated pulmonary infections with Aspergillus, leading to multiple hospitalizations and long-term antifungal prophylaxis with voriconazole. A bone scan from an outside hospital was reviewed, and further imaging was performed.

Disruption of the proximal tibiofibular joint in the setting of multi-ligament knee injury.

Instability of the proximal tibiofibular joint is a relatively uncommon condition when in isolation; however, instability of the proximal tibiofibular joint is far more frequent in those presenting with a severe multi-ligament injury of the knee. If this joint is left unstable, repair of a co-existent injury of the posterolateral corner may fail, regardless of the proficiency of the technique. We present two patients with disruption of the proximal tibiofibular joint, including the MRI appearance, who initially presented to our hospital for management of significant polytrauma, as well as multi-ligament injury of the ipsilateral knee.

The acetabular fossa hot spot on 18F-FDG PET/CT: epidemiology, natural history, and proposed etiology.

OBJECTIVE: To describe a benign focus of increased activity in the acetabular fossa (the acetabular fossa hot spot, AFHS) on (18) F-FDG PET/CT that can mimic a neoplasm. MATERIALS AND METHODS: (18)F-FDG PET/CT images from four patient populations were examined. Group 1 (n = 13) was collected from a search of radiology reports and used to define the AFHS and for hypothesis generation. Group 2 (n = 1,150) was used for prevalence of AFHS. Group 3 (n = 1,213) had PET/CT and MRI pelvis within a week of each other and was used to correlate metabolic and anatomic findings. Group 4 (n = 100) was used to generate the control group. Data were collected on demographics, common comorbidities, underlying cancer diagnosis and status, and hip symptoms. RESULTS: Prevalence of AFHS was 0.36 % (95 % CI 0.10-0.91 %). None progressed to malignancy or was associated with cancer status. The majority (71 %) were on the left, and 6 % were bilateral. Mean SUVmax of the AFHS was 4.8 (range, 2.7-7.8). Male patients were more likely to have the AFHS (OR = 8.69, 95 % CI 1.88-40.13). There was no difference with respect to other collected data, including hip symptoms. Average minimum duration of AFHS was 346 days (range, 50-1,010 days). Readers did not detect corresponding hip abnormalities on MRIs. CONCLUSIONS: AFHS is a benign finding that may be caused by subclinical ligamentum teres injury, focal synovitis, or degeneration of acetabular fossa fat. Despite uncertainty regarding its etiology, recognition of AFHS as a benign finding can prevent morbidity associated with unnecessary biopsy or initiation of therapy.

Wellness in the radiology reading room: making your workstation a workout station.

OBJECTIVE: Sitting can be dangerous to one's health, and radiology tends to be a sedentary profession. CONCLUSION: By adding a mixture of technological and behavioral changes to our workplaces, we can put a large dent in the amount of sedentary time we spend at work.

Biostatistics primer for the radiologist.

OBJECTIVE: The purpose of this article is to review the most common data analysis methods encountered in radiology-based studies. Initially, description of variable types and their corresponding summary measures are provided; subsequent discussion focuses on comparison of these summary measures between groups, with a particular emphasis on regression analysis. CONCLUSION: Knowledge of statistical applications is critical for radiologists to accurately evaluate the current literature and to conduct scientifically rigorous studies. Misapplication of statistical methods can lead to inappropriate conclusions and clinical recommendations.

Fetal lung maturity assessment with MRI fetal lung-to-liver signal-intensity ratio.

OBJECTIVE: The purpose of this study was to retrospectively determine whether the ratio of fetal lung-to-liver signal intensities at single-shot fast spin-echo MRI is associated with fetal gestational age. MATERIALS AND METHODS: All fetal MRI examinations over a 4-year period were reviewed. All MRI examinations were performed with a 1.5-T magnet for indications other than lung maturity. Only examinations performed with a single-shot fast spin-echo sequence of the fetal chest and abdomen were included in the study. Images from a total of 82 fetal MRI examinations were evaluated. Gestational age ranged from 20 weeks to 39 weeks 3 days. Two board-certified subspecialty-trained radiologists with 11 and 17 years of experience blinded to estimated gestational age (EGA) reviewed the images independently. The regions of interest (ROIs) of the fetal lung and liver were drawn in the same plane and on the same image in each case. Fetal EGA was determined either by first-trimester ultrasound when available or by last menstrual period. Linear regression analysis was used to analyze the relation between the lung-to-liver signal-intensity ratio (LLSIR) in the ROIs and fetal EGA for both readers. The association between the LLSIRs estimated by the two readers was assessed by Bland-Altman plot. RESULTS: Summary statistics for LLSIR showed a median value of 2.29 for reader 1 and 2.21 for reader 2. The mean value for reader 1 was 2.4 and for reader 2 was 2.5. The Pearson correlation coefficients between the LLSIR and EGA variables were 0.44 for reader 1 and 0.45 for reader 2. Linear regression analysis showed a statistically significant association between LLSIR and EGA for both readers (p < 0.0004). This ratio increased in a linear manner as EGA progressed. CONCLUSION: Fetal LLSIR at single-shot fast spin-echo MRI is associated with fetal gestational age.

Imaging key wrist ligaments: what the surgeon needs the radiologist to know.

OBJECTIVE: Although much attention is paid to the scapholunate ligament, lunotriquetral ligament, and the triangular fibrocartilage complex, additional intrinsic and extrinsic ligaments in the wrist play an important part in carpal stability. With improved MRI techniques, the radiologist can increasingly visualize these ligaments. CONCLUSION: The anatomy, MRI appearance, and clinical significance of the scapholunate ligament, lunotriquetral ligament, triangular fibrocartilage complex, carpal metacarpal ligaments, and volar and dorsal extrinsic ligaments are reviewed.

Comparing Ultrasound with Magnetic Resonance Imaging in the Evaluation of Subungual Glomus Tumors and Subungual Myxoid Cysts.

Introduction: Subungual myxoid cysts and subungual glomus tumors demonstrate characteristic features on magnetic resonance imaging (MRI) and ultrasound (US). It is not yet well-established whether US is congruent to MRI in diagnostic evaluation of these subungual lesions. Methods: Participants with clinical suspicion for subungual glomus tumors or subungual myxoid cysts were recruited. After clinical evaluation, participants underwent radiography, MRI, and US plus biopsy, aspiration, or excision where possible. Differential diagnoses were revised after review of imaging, and imaging findings were compared to definitive diagnosis by pathology, aspiration, or clinical course. Results: All lesions were visible on both US and MRI and size estimates agreed between the two modalities. US and MRI findings of subungual glomus tumors and subungual myxoid cysts agreed with their known respective imaging characteristics. Conclusions: Diagnosis of subungual myxoid cysts and subungual glomus tumors agreed between US and MRI. We provide sample MRI and US imaging parameters for optimal evaluation of subungual myxoid cysts and glomus tumors. We demonstrate that subungual MRI evaluation can be performed without special equipment, allowing for evaluation by most radiology departments. Lastly, US is user-dependent and may be non-inferior for a sonographer familiar with subungual US.

Teaching with Technology-Matching Pedagogy with Purpose in Radiology Education.

The response to pandemic-related teaching disruption has revealed dynamic levels of learning and teaching flexibility and rapid technology adoption of radiology educators and trainees. Shutdowns and distancing requirements accelerated the adoption of technology as an educational tool, in some instances supplanting in-person education entirely. Despite the limitations of remote interaction, many educational advantages were recognized that can be leveraged in developing distance learning paradigms. The specific strategies employed should match modern learning science, enabling both students and educators to mutually grow as lifelong learners. As panel members of the "COVID: Faculty perspective" Task Force of the Association of University Radiologists Radiology Research Alliance, we present a review of key learning principles which educators can use to identify techniques that enhance resident learning and present an organized framework for applying technology-aided techniques aligned with modern learning principles. Our aim is to facilitate the purposeful integration of learning tools into the training environment by matching these tools to established educational frameworks. With these frameworks in mind, radiology educators have the opportunity to re-think the balance between traditional curricular design and modern digital teaching tools and models.

Software Aids for radiologists: Part 2, Essential apps for handheld devices.

OBJECTIVE: The purpose of this review is to summarize applications (apps) for hand-held computing devices that can be essential aids to radiologists. CONCLUSION: Numerous apps are relevant to radiologists. Although the author prefers Apple iPad and iPhone apps, similar Android apps fill many of the same software niches.

Interactive Web-based learning module on CT of the temporal bone: anatomy and pathology.

An interactive Web-based learning module on the temporal bone has been developed. It shows normal temporal bone anatomy in four imaging planes: axial, coronal, and parallel and perpendicular to the long axis of the petrous bone. After reviewing the normal anatomy, users should be able to identify key imaging features of pathologic conditions of the temporal bone. Children with congenital abnormalities of the temporal bone may present with conductive or sensorineural hearing loss or both and may have a genetic syndrome. Acute otitis media is the most common infection of the temporal bone and is most prevalent among children. Although imaging is unnecessary in uncomplicated otitis media, it is important for evaluation of infectious complications. Classically, temporal bone fractures were described as longitudinal or transverse with respect to the long axis of the petrous bone. However, it is increasingly recognized that many fractures have both longitudinal and transverse components. Patients with temporal bone fractures may have conductive or sensorineural hearing loss in addition to other complications. The most common tumor of the temporal bone at the cerebellopontine angle is the vestibular schwannoma. Paraganglioma is the second most common tumor of the temporal bone and the most common tumor of the middle ear. Supplemental material available at http://uwmsk.org/temporalbone/atlas.html.