Savings in CT Net Scan Energy Consumption: Assessment Using Dose Report Metrics and Comparison With Savings in Idle State Energy Consumption.

BACKGROUND. CT scanners' net scan state (i.e., image acquisition period) represents a potential target for energy savings through protocol adjustments. However, gauging CT energy savings is difficult without installing costly energy monitors. OBJECTIVE. The purpose of this article was to assess correlations between CT dose report metrics and energy consumption during the system net scan state and to compare theoretic energy savings from matching percentage reductions in energy consumption during net scan and idle system states. METHODS. Current sensors were installed on a single CT scanner. A phantom was scanned at varying kilovoltage settings and effective tube current-rotation time settings. A retrospective assessment was performed in 32 patients (mean age, 61.2 ± 17.9 [SD] years; 17 men, 15 women) who underwent 32 single-energy noncontrast abdominopelvic CT examinations from September 22, 2021, to September 27, 2021, on the same scanner. Correlations between dose report metrics and net scan energy consumption were assessed in the phantom and clinical scans, and equations were generated to derive net scan energy consumption from DLP. An additional retrospective assessment was performed in 1355 patients (mean age, 59.3 ± 16.9 years; 663 men, 692 women) who underwent 1728 single-energy noncontrast abdominopelvic CT examinations from January 1, 2021, through December 31, 2021, on the same scanner to estimate net scan energy consumption per examination. This information was integrated with literature-derived values to compare estimated annual national energy savings resulting from 20% reductions in net scan and idle state energy consumption. RESULTS. Net scan energy consumption in the phantom scans showed high linear correlation with DLP (R2 = 0.87), and, in the clinical scans, high linear correlation with CTDIvol (R2 = 0.89) and very high linear correlation with DLP (R2 = 0.92). When combining mean DLP in examinations performed in the 1-year interval, an equation relating DLP and net scan energy consumption and literature values estimated that annual national energy savings was 14.9 times greater (40,437,870 kWh/2,704,000 kWh) by targeting the idle state rather than net scan state. CONCLUSION. CT net scan energy savings can be inferred from reductions in dose report metrics. However, targeting net scan energy consumption has modest impact relative to targeting idle state energy consumption. CLINICAL IMPACT. Environmental sustainability efforts should target the idle state energy consumption of CT.

Study of the Natural Crystalline Lens Characteristics Using Dual-Energy Computed Tomography.

There is a paucity of radiologic literature regarding age-related cataract, and little is known about any differences in the imaging appearance of the natural crystalline lens on computed tomography (CT) exams among different demographic groups. In this retrospective review of 198 eyes in 103 adults who underwent dual-energy computed tomography (DECT) exams of the head, regions of interest spanning 3−5 mm were placed over the center of the lens, and the x-ray attenuation of each lens was recorded in Hounsfield Units (HU) at 3 energy levels: 40 keV, 70 keV, and 190 keV. Generalized estimating equations (GEEs) were used to assess the association of clinical or demographic data with lens attenuation. The mean HU values were significantly lower for the older vs. younger group at 40 keV (GEE p-value = 0.022), but there was no significant difference at higher energy levels (p > 0.05). Mean HU values were significantly higher for females vs. males and non-whites vs. non-Hispanic whites at all 3 energy levels in bivariate and multivariable analyses (all p-value < 0.05). There was no significant association between lens attenuation and either diabetes or smoking status. The crystalline lens of females and non-whites had higher attenuation on DECT which may suggest higher density or increased concentration of materials like calcium and increased potential for cataract formation. Given the large scope of cataracts as a cause of visual impairment and the racial disparities that exist in its detection and treatment, further investigation into the role of opportunistic imaging to detect cataract formation is warranted.

Magnetic Resonance Imaging of Head and Neck Emergencies, a Symptom-Based Review, Part 1: General Considerations, Vision Loss, and Eye Pain.

Use of magnetic resonance (MR) imaging in the emergency department continues to increase. Although computed tomography is the first-line imaging modality for most head and neck emergencies, MR is superior in some situations and imparts no ionizing radiation. This article provides a symptom-based approach to nontraumatic head and neck pathologic conditions most relevant to emergency head and neck MR imaging, emphasizing relevant anatomy, "do not miss" findings affecting clinical management, and features that may aid differentiation from potential mimics. Essential MR sequences and strategies for obtaining high-quality images when faced with patient motion and other technical challenges are also discussed.

Magnetic Resonance Imaging of Head and Neck Emergencies, a Symptom-Based Review, Part 2: Ear Pain, Face Pain, and Fever.

The use of magnetic resonance (MR) imaging in the emergency department continues to increase. Although computed tomography is the first-line imaging modality for most head and neck emergencies, MR is superior in some situations and imparts no ionizing radiation. This article provides a symptom-based approach to nontraumatic head and neck pathologic conditions most relevant to emergency head and neck MR imaging, emphasizing relevant anatomy, "do not miss" findings affecting clinical management, and features that may aid differentiation from potential mimics. Essential MR sequences and strategies for obtaining high-quality images when faced with patient motion and other technical challenges are also discussed.

Cranial Nerve Anatomy Using a Modular and Multimodal Radiologic Approach.

Introduction: Medical students often struggle with learning cranial nerve anatomy. Typically, cranial nerve anatomy is taught using didactic lectures and textbook illustrations, often leaving students frustrated. Methods: We developed a multimodal radiologic approach to teaching cranial nerve anatomy. First, 150 students were presented with carefully curated preclass material from which to prepare. Next, they received a didactic lecture that was recorded for them to revisit on their own time. Last, students worked in groups in a lab setting with expert radiologists to identify the cranial nerves and related anatomy and learn about some basic pathophysiology. We used a pretest and posttest to examine the effectiveness of our teaching methods and a survey to measure students' satisfaction. Results: Student knowledge of cranial nerve structure was significantly improved after our module, with quiz scores increasing from 4.6 to 6.8 out of 9.0 (p < .001). In addition, students reported feeling more confident in their knowledge of the material and offered high satisfaction scores. Discussion: The breadth of knowledge covered during the preclinical training years continues to expand despite stable or even contracted durations of training, requiring knowledge to be delivered in an ever more efficient manner. Ultimately, the multimodal pedagogy used by our resource leads to students who are more confident and engaged in their learning, resulting in increased knowledge.

An Unusual Etiology of Lemierre-Like Syndrome: Preseptal Cellulitis due to Methicillin-Resistant Staphylococcus aureus.

Lemierre's syndrome (LS) is a rare and potentially fatal condition that predominantly affects young adults with oropharyngeal infection. Fusobacterium necrophorum is the usual etiology and classically causes internal jugular vein septic thrombophlebitis, frequently complicated by septic emboli to several organs (most classically to the lungs). Lemierre-like syndrome (LLS) describes the same constellation of symptoms and pathophysiology as Lemierre's syndrome; however, Fusobacterium spp. are not the cause, and the source of infection may be nonoropharyngeal. We present a case with an unusual etiology of LLS: a patient with untreated preseptal cellulitis and associated methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in the setting of injection drug use. Physical exam revealed tachypnea and rhonchi with severe periorbital and bilateral eyelid edema. Imaging demonstrated bilateral preseptal and orbital cellulitis with thrombosis of both internal jugular veins and bilateral pulmonary cavitary lesions consistent with septic pulmonary emboli. She was managed with anticoagulation and parenteral antibiotics. To our knowledge, this is the first case of LLS originating from preseptal cellulitis without evidence of preceding pharyngitis. While facial and orbital infections are rare etiologies of LLS, the potentially devastating sequelae of LLS warrant its inclusion in differential diagnoses.

Accuracy of 190-keV Virtual Monoenergetic Dual-Energy CT for Determining the Presence or Absence of Intravitreal Silicone Oil.

OBJECTIVE. We hypothesized that intravitreal silicone oil would show attenuation similar to that of fat on dual-energy CT 190-keV virtual monoenergetic images (VMIs) with high frequency and that this appearance would enable confident determination of the presence or absence of intravitreal silicone oil. The purpose of the present study was to test our hypothesis in a blinded multireader study of selected patients with and without intravitreal silicone oil as well as in an unblinded ROI-based assessment. MATERIALS AND METHODS. In this retrospective study of 50 dual-energy CT examinations of the head that included 100 globes (64 that were normal, 19 that exhibited hyperattenuating mimics, and 17 that contained silicone oil), three neuroradiologists independently assessed anonymized 190-keV VMIs for intravitreal attenuation similar to that of fat. Interobserver agreement was calculated. The mean attenuation value on weighted-average images and 190-keV VMIs was recorded. RESULTS. The three readers identified intravitreal attenuation values similar to that of fat in 100% of globes that contained silicone oil and 0% of globes that did not contain silicone oil (100% sensitivity, specificity, PPV, and accuracy) with 100% agreement. The mean attenuation value of silicone oil on 190-keV VMIs was -55 HU, which was significantly less than the mean attenuation on 190-keV VMIs of normal globes and hyperattenuating mimics (p < .001 for both). CONCLUSION. Intravitreal silicone oil shows attenuation of -60 to -49 HU on 190-keV VMIs. With the use of these images only, three neuroradiologists identified intravitreal silicone oil with 100% accuracy and perfect agreement.

Intrathecal delivery of nusinersen in individuals with complicated spines.

BACKGROUND: The treatment of spinal muscular atrophy (SMA) with nusinersen requires intrathecal medication administration, which can be challenging in individuals with complicated spines. This retrospective case series reviews the nusinersen treatment experience at one academic medical center with children and adults with SMA and complicated spines. METHODS: Twenty medical records of individuals receiving nusinersen were reviewed and administration methods summarized and assessed. RESULTS: Ten children and 10 adults were treated, and 55% had complicated spines. In total, 163 treatments were given, 91 in those with complicated spines. In the complicated spines, 74% of treatments were done by means of fluoroscopic lumbar puncture, 22% by means of intrathecal Ommaya reservoir, 3% by means of palpation, and < 1% by means of computed tomography-guided transforaminal approach. CONCLUSIONS: A large majority of individuals with complicated spines can receive intrathecal nusinersen using fluoroscopic guidance in the lumbar region. Other delivery methods are available but less frequently used.

Unique Characteristics of Intravitreal Silicone Oil on Dual-Energy Computed Tomography.

Silicone oil is used as an intravitreal injection to treat retinal detachment. This material can spread into the subarachnoid space, where it may be mistaken for acute hemorrhage on single-energy computed tomography. This report describes the appearance of intravitreal silicone oil on dual-energy computed tomography, emphasizing unique virtual monoenergetic imaging characteristics that allow for confident differentiation of silicone oil from hemorrhage as well as from other potential single-energy mimics, such as calcium and iodine.

How to Incorporate Dual-Energy Computed Tomography Into Your Neuroradiology Practice: Questions and Answers.

Dual-energy computed tomography (DECT) has many current and evolving applications in neuroradiology including material decomposition, improving conspicuity of iodinated contrast enhancement, and artifact reduction. However, there are multiple challenges in incorporating DECT into practice including hardware selection, postprocessing software requirements, technologist and physician training, and numerous workflow issues. This article reviews in a question-and-answer format common issues that arise when incorporating DECT into a busy neuroradiology practice.

Arterial spin-labeled magnetic resonance imaging in hyperperfused seizure focus: a case report.

We present a case of a clinically suspected cerebral infarction that was diagnosed as a seizure focus on pulsed arterial spin labeling. The finding of hyperperfusion with perfusion imaging significantly impacted clinical management of the patient.

Evaluation of critical formulation factors in the development of a rapidly dispersing captopril oral dosage form.

New methods of manufacture have enabled the creation of novel dosage forms with unique rapid-dispersion properties. This study combines one such technique with a statistical experimental design to develop dosage forms from captopril, an angiotensin-converting enzyme inhibitor used to treat cases of hypertensive emergency. The TheriForm process, a novel microfabrication technique, was used to build the dosage forms in a layer-by-layer fashion. Three key formulation factors were chosen for the design of experiments. A modified central composite design (Box-Behnken design) was used to maximize the efficiency of the experiments. A total of 13 distinct formulations were fabricated and tested, using mannitol as the bulk excipient. In addition, three replicates of the center point were tested to assess variability and experimental error. These formulations were tested for speed of dispersion (flash time), active content, hardness, friability, and moisture absorption. Regression analysis was performed to fit data responses to quadratic equations. Excellent dose accuracy (95% to 102% of target) and content uniformity (between 1.03% to 2.84%) were observed from all experimental formulation batches. As expected, the choice of powder additive (maltitol, maltodextrin, polyvinyl pyrrolidone), level of additive (2.5% to 7.5%), and saturation level of the binder liquid (45% to 65%) were all found to be significant factors for the TheriForm process. The regression analysis suggested that a rapidly dispersing dosage form of optimal physical properties would be obtained when a powder mixture of mannitol (97.5%) and maltitol (2.5%) is used at a saturation level of 45%. In conclusion, rapidly dispersing captopril oral dosage forms were successfully fabricated and tested. A wide range of physical properties, flash time, and hardness, were determined experimentally, and the effects of key formulation factors were identified.