Utility of Dual-Energy Computed Tomography in Clinical Conundra.

Advancing medical technology revolutionizes our ability to diagnose various disease processes. Conventional Single-Energy Computed Tomography (SECT) has multiple inherent limitations for providing definite diagnoses in certain clinical contexts. Dual-Energy Computed Tomography (DECT) has been in use since 2006 and has constantly evolved providing various applications to assist radiologists in reaching certain diagnoses SECT is rather unable to identify. DECT may also complement the role of SECT by supporting radiologists to confidently make diagnoses in certain clinically challenging scenarios. In this review article, we briefly describe the principles of X-ray attenuation. We detail principles for DECT and describe multiple systems associated with this technology. We describe various DECT techniques and algorithms including virtual monoenergetic imaging (VMI), virtual non-contrast (VNC) imaging, Iodine quantification techniques including Iodine overlay map (IOM), and two- and three-material decomposition algorithms that can be utilized to demonstrate a multitude of pathologies. Lastly, we provide our readers commentary on examples pertaining to the practical implementation of DECT's diverse techniques in the Gastrointestinal, Genitourinary, Biliary, Musculoskeletal, and Neuroradiology systems.

The Role of Dual-Energy CT in Solid Organ Injury.

The liver, spleen, and kidneys are the commonest injured solid organs in blunt and penetrating trauma. The American Association for the Surgery of Trauma (AAST) Organ Injury Scale (OIS) is the most widely accepted system for categorizing traumatic injuries. Grading systems allow clear communication of findings between clinical teams and assign a measurable severity of injury, which directly correlates with morbidity and mortality. The 2018 revised AAST OIS emphasizes reliance on CT for accurate grading; in particular regarding vascular injuries. Dual-Energy CT (DECT) has emerged as a promising tool with multiple clinical applications already demonstrated. In this review article, we summarize the basic principles of CT attenuation to refresh the minds of our readers and we scrutinize DECT's technology as opposed to conventional Single-Energy CT (SECT). This is followed by outlining the benefits of various DECT postprocessing techniques, which authors of this article refer to as the 3Ms (Mapping of Iodine, Material decomposition, and Monoenergetic virtual imaging), in aiding radiologists to confidently assign an OIS as well as problem solve complex injury patterns. In addition, a thorough discussion of changes to the revised AAST OIS focusing on definitions of key terms used in reporting injuries is described.

Dual Energy Computed Tomography Collagen Material Decomposition for Detection of Lumbar Spine Disc Extrusion and Sequestration: A Comparative Study With Greyscale Computed Tomography.

Purpose: To assess value of dual energy computed tomography (DECT) collagen material decomposition algorithm when combined with standard computed tomography (CT) in detection of lumbar disc extrusion and sequestration. Materials and Methods: Retrospective analysis of all patients with acute low back pain who had a diagnosis of lumbar spine disc extrusion and/or sequestration on Magnetic Resonance Imaging (MRI) (reference standard), and had undergone non-contrast DECT of the lumbar spine within 60 days of the MRI. Age and sex-matched control patients (n = 42) were included. Patients were grouped into standard, grey-scale CT only group and standard CT + DECT tendon images group. Two double-blinded radiologists reviewed both groups for presence of extrusion or sequestration. They also rated their diagnostic confidence on Likert 5-point scale. McNemar Chi-square test was used to compare diagnostic accuracy, unpaired t-test to compare reviewers diagnostic confidence, and Cohen's k (kappa) test for interobserver agreement. Results: The combined group showed higher overall sensitivity (96.6% vs 87.2%), specificity (99% vs 95.4%), and diagnostic accuracy (98.7% vs 94.5%) with a lower false positive rate (1.1% vs 4.6%). McNemar Chi-square test confirmed statistical significance (P = .03 and P = .02 for Reviewers R1 and R2, respectively). The mean diagnostic confidence was also significantly higher on combined group (R1: 3.74 ± 1.1 vs 3.47 ± 1.15 (P < .01) and R2: 3.91 ± 1.15 vs 3.72 ± 1.16 [mean ± SD] (P = .02)). Conclusion: Utilizing MRI as a reference standard, DECT tendon application combined with standard CT increases the sensitivity, specificity, and accuracy of detection of lumbar spine disc extrusion and sequestration, when compared to standard CT alone.

Gender Disparity in Radiology Society Committees and Leadership in North America and Comparison With Other Continents.

PURPOSE: To evaluate gender distribution in radiology professional society leadership positions. Our study intends to assess and compare the gender distribution among leadership roles and professional society committee memberships of the radiology societies and seek an understanding of potential associations between gender, academic research metrics, institutional academic rank, and leadership roles. METHODS: We identified radiology professional society committee members to assess relative gender composition in 28 radiology societies in North America, Europe, and Australia/New Zealand. The research metrics were obtained from the SCOPUS database and demographics and institutional affiliation through institutional websites' internet searches. Gender distribution by academic ranks and other discontinuous variables were analyzed using the Chi-Square test. Wallis tests. RESULTS: Of the 3011 members of society committees, 67.9% were male, and 32.1% female. Among all the society members, the data showed that the proportion of committee members holding leadership positions was comparable between males (25.7%) and females (22.5%). However, when we did a subgroup analysis and disaggregated the data by leadership positions, we noted that among those who held the leadership positions, the proportion of males was more significant (n = 526, 70.7%) compared to females (n = 218, 29.3%). Overall, males had higher median publications, citations, H-indices, and active years of research (P< 0.0001). At all university academic ranks, men outnumbered females (P = 0.0015, Chi-square 15.38), with the most considerable disparity at the rank of professor (71.9% male, 28.1% female, P = 0.0003). CONCLUSION: There was male predominance amongst committee members in radiology societies. Our study found no significant differences between those in leadership positions, suggesting that once a member of a committee, females are equally likely as males to attain leadership positions. Analysis of committee members' academic rank and committee leaders demonstrated underrepresentation of females at higher academic ranks, and males overall had higher research metrics than females.

Clinical Utility of Dual-Energy CT Analysis of Bone Marrow Edema in Acute Wrist Fractures.

OBJECTIVE: The purpose of this study is to determine the utility of dual-energy CT (DECT) for assessing carpal fractures and to obtain an attenuation value cutoff (in Hounsfield units) to identify bone marrow edema due to an acute carpal fracture. MATERIALS AND METHODS: In this retrospective study, 24 patients who presented with wrist fractures from September 3, 2014, through March 9, 2015, underwent imaging with DECT (80 and 140 kVp). Using the three-material decomposition algorithm specific for virtual noncalcium to construct images, two radiologists identified carpal fractures and associated bone marrow edema. Readers noted the attenuation at areas with and without bone marrow edema. The cutoff value was obtained by ROC analysis and was internally validated on 13 separate patients with suspected wrist fractures. A p < 0.05 was considered statistically significant. RESULTS: CT attenuation was significantly higher in areas of bone marrow edema than in areas without it (p < 0.0001, t test). A cutoff of 5.90 HU allows detection of bone marrow edema associated with acute wrist fractures with 100% sensitivity and 99.5% specificity, compared with visual DECT interpretation. In the 13 validation cases, the cutoff of 5.90 HU identified bone marrow edema with 100% accuracy, compared with visual interpretation. Kappa values were 0.83 between the two readings by reader 1, and 0.73 and 0.96 comparing the two readings of reader 1 with the reading by reader 2. CONCLUSION: DECT is a useful tool for identifying bone marrow edema in the setting of acute wrist fractures, providing an alternative to MRI. A cutoff value of 5.90 HU can be used for accurate diagnosis and exclusion of carpal fractures.

Faster magnetic resonance imaging in emergency room patients with right lower quadrant pain and suspected acute appendicitis.

PURPOSE: Emergency Departments (ED) are becoming busier, with a resultant increase in the number of imaging referrals. The purpose of this study was to assess the diagnostic accuracy of an abbreviated two sequence magnetic resonance (MR) protocol for evaluating ED patients with right lower quadrant pain and suspected acute appendicitis, with a view to expediting patient turnaround times and imaging costs. MATERIAL AND METHODS: Fifty patients (49 females, one male; mean age 25.4 ± 5.2 years) who underwent ED MR imaging from July 2014 to March 2015 for right lower quadrant pain were retrospectively reviewed. MR abdomen/pelvis was performed on 1.5 T MR obtaining axial T1 gradient echo in/out of phase, transverse fast spin echo T2 with fat sat/motion correction, axial/coronal T2 HASTE (half-Fourier acquisition single-shot turbo spin-echo), and axial DWI (diffusion-weighted imaging) sequences. Images were reviewed by two fellowship-trained radiologists on a five-point confidence scale. Mean acquisition/interpretation times for the standard departmental protocol and the proposed abbreviated MR protocol (comprising T2 HASTE and DWI images) were calculated. Sensitivity, specificity, and diagnostic accuracy for the abbreviated protocol against the full protocol were also calculated. RESULTS: Mean scanning time for abbreviated protocol and standard protocol was calculated to be 21.1 minutes and 40.5 minutes, respectively. Mean interpretation time for abbreviated protocol for reader one and two was 4.1 ± 1.5 minutes and 4.5 ± 1.4 minutes, respectively, and for standard protocol was 8.1 ± 1.8 minutes and 7.1 ± 1.4 minutes, respectively. Sensitivity, specificity, and accuracy for the FAST protocol were calculated to be 100% each for reader one and 75%, 100%, and 94%, respectively, for reader two. CONCLUSIONS: The proposed abbreviated MR protocol has comparable diagnostic accuracy in diagnosing ED patients with right lower quadrant pain, with significant reduction in imaging/interpretation times. It thus has the potential to be implemented in ED imaging with significant reduction in patient turnaround times and costs.