Observing inhibition of the SARS-CoV-2 helicase at single-nucleotide resolution.

The genome of SARS-CoV-2 encodes for a helicase (nsp13) that is essential for viral replication and highly conserved across related viruses, making it an attractive antiviral target. Here we use nanopore tweezers, a high-resolution single-molecule technique, to gain detailed insight into how nsp13 turns ATP-hydrolysis into directed motion along nucleic acid strands. We measured nsp13 both as it translocates along single-stranded DNA or unwinds double-stranded DNA. Our data reveal nsp13's single-nucleotide steps, translocating at ∼1000 nt/s or unwinding at ∼100 bp/s. Nanopore tweezers' high spatiotemporal resolution enables detailed kinetic analysis of nsp13 motion. As a proof-of-principle for inhibition studies, we observed nsp13's motion in the presence of the ATPase inhibitor ATPγS. We construct a detailed picture of inhibition in which ATPγS has multiple mechanisms of inhibition. The dominant mechanism of inhibition depends on the application of assisting force. This lays the groundwork for future single-molecule inhibition studies with viral helicases.

Improving Radiographic Fracture Recognition Performance and Efficiency Using Artificial Intelligence.

Background Missed fractures are a common cause of diagnostic discrepancy between initial radiographic interpretation and the final read by board-certified radiologists. Purpose To assess the effect of assistance by artificial intelligence (AI) on diagnostic performances of physicians for fractures on radiographs. Materials and Methods This retrospective diagnostic study used the multi-reader, multi-case methodology based on an external multicenter data set of 480 examinations with at least 60 examinations per body region (foot and ankle, knee and leg, hip and pelvis, hand and wrist, elbow and arm, shoulder and clavicle, rib cage, and thoracolumbar spine) between July 2020 and January 2021. Fracture prevalence was set at 50%. The ground truth was determined by two musculoskeletal radiologists, with discrepancies solved by a third. Twenty-four readers (radiologists, orthopedists, emergency physicians, physician assistants, rheumatologists, family physicians) were presented the whole validation data set (n = 480), with and without AI assistance, with a 1-month minimum washout period. The primary analysis had to demonstrate superiority of sensitivity per patient and the noninferiority of specificity per patient at -3% margin with AI aid. Stand-alone AI performance was also assessed using receiver operating characteristic curves. Results A total of 480 patients were included (mean age, 59 years ± 16 [standard deviation]; 327 women). The sensitivity per patient was 10.4% higher (95% CI: 6.9, 13.9; P < .001 for superiority) with AI aid (4331 of 5760 readings, 75.2%) than without AI (3732 of 5760 readings, 64.8%). The specificity per patient with AI aid (5504 of 5760 readings, 95.6%) was noninferior to that without AI aid (5217 of 5760 readings, 90.6%), with a difference of +5.0% (95% CI: +2.0, +8.0; P = .001 for noninferiority). AI shortened the average reading time by 6.3 seconds per examination (95% CI: -12.5, -0.1; P = .046). The sensitivity by patient gain was significant in all regions (+8.0% to +16.2%; P < .05) but shoulder and clavicle and spine (+4.2% and +2.6%; P = .12 and .52). Conclusion AI assistance improved the sensitivity and may even improve the specificity of fracture detection by radiologists and nonradiologists, without lengthening reading time. Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Link and Pedoia in this issue.

Intra-articular Corticosteroid Injections in the Hip and Knee: Perhaps Not as Safe as We Thought?

Osteoarthritis (OA) of the hip and knee is among the most common joint disorders. Intra-articular corticosteroid (IACS) injections are frequently performed to treat OA and other joint-related pain syndromes; however, there is conflicting evidence on their potential benefit. There is a lack of prospective and large retrospective studies evaluating potential joint findings, including increased risk for accelerated OA progression or adverse joint events, after treatment with IACS injection. Four main adverse joint findings have been structurally observed in patients after IACS injections: accelerated OA progression, subchondral insufficiency fracture, complications of osteonecrosis, and rapid joint destruction, including bone loss. Physicians, including radiologists, should be familiar with imaging findings and patient characteristics that may help them identify potential joints at risk for such events. The purpose of this report is to review the existing literature, describe observed adverse joint events after IACS injections, and provide an outlook on how this may affect clinical practice. Additional research endeavors are urgently needed to better understand and identify risk factors prior to intervention and to detect adverse joint events after injection as early as possible to prevent or minimize complications.

MRI-Detected Sports-Related Knee Injuries and Abnormalities at the Rio de Janeiro 2016 Summer Olympic Games.

OBJECTIVE: The purpose of this article is to describe knee abnormalities and the occurrence of MRI-detected sports-related knee abnormalities by evaluating MRI examinations performed during the Rio de Janeiro Olympic Games held in August 2016. CONCLUSION: There were 11,274 athletes at the Rio 2016 Olympic Games, and 113 of them underwent at least one knee MRI in the Olympic Village. Cartilage abnormalities, followed by meniscal tears and ligament sprains, were the most frequent abnormalities.

Acute Radiologic Manifestations of America's Opioid Epidemic.

The United States is in the midst of an opioid use epidemic, which has severe medical, social, and economic consequences. Addictions to and abuse of prescription and illicit opioids are increasing, and emergency department radiologists are increasingly being faced with the task of examining patients who present with opioid-related complications. These complications may be the result of direct drug toxicity or nonsterile injection of the drugs. Neurologic, musculoskeletal, cardiopulmonary, genitourinary, and gastrointestinal complications may be evident at diagnostic imaging in emergent settings. Heroin-induced leukoencephalopathy, cerebral septic emboli, mycotic arterial aneurysms, soft-tissue infections, and infective endocarditis are some of the conditions that patients may be found to have after they present to the emergency department. In this article, the above topics, including clinical features, pathophysiology, imaging findings, and treatment options, are reviewed. Recognizing the limitations of diagnostic imaging modalities that are available to radiologists is equally important, as some conditions can be successfully diagnosed after the initial triage-for example, transesophageal echocardiography can be performed to diagnose infective endocarditis. The emergency department radiologist may be responsible for identifying acute conditions, which can be life threatening. Some of the more common emergent opioid-related conditions and complications are reviewed, with specific emphasis on cases in which emergency department radiologists encounter conditions for which additional expertise is required. Becoming familiar with the conditions directly related to the current opioid epidemic will enable the diagnosis of these entities in a timely and accurate manner. ©RSNA, 2018.

The epidemiology of MRI detected shoulder injuries in athletes participating in the Rio de Janeiro 2016 Summer Olympics.

BACKGROUND: To use Magnetic Resonance Imaging (MRI) to characterize the severity, location, prevalence, and demographics of shoulder injuries in athletes at the Rio de Janeiro 2016 Summer Olympic Games. METHODS: This was a retrospective analysis of all routine shoulder MRIs obtained from the Olympic Village Polyclinic during the Rio 2016 Summer Olympics. Imaging was performed on 1.5 T and 3 T MRI, and interpretation was centrally performed by a board-certified musculoskeletal radiologist. Images were assessed for tendon, muscle, bone, bursal, joint capsule, labral, and chondral abnormality. RESULTS: A total of 11,274 athletes participated in the Games, of which 55 (5%) were referred for a routine shoulder MRI. Fifty-three (96%) had at least two abnormal findings. Seven (13%) had evidence of an acute or chronic anterior shoulder dislocation. Forty-nine (89%) had a rotator cuff partial tear and / or tendinosis. Subacromial / subdeltoid bursitis was present in 29 (40%). Thirty (55%) had a tear of the superior labrum anterior posterior (SLAP). CONCLUSION: Our study demonstrated a high prevalence of both acute and chronic shoulder injuries in the Olympic athletes receiving shoulder MRI. The high rates of bursal, rotator cuff, and labral pathology found in these patients implies that some degree of glenohumeral instability and impingement is occurring, likely due to fatigue and overuse of the dynamic stabilizers. Future studies are needed to better evaluate sport-specific trends of injury.

Rotator Cuff Tear Arthropathy: Pathophysiology, Imaging Characteristics, and Treatment Options.

OBJECTIVE: The purpose of this article is to review the biomechanical properties of the rotator cuff and glenohumeral joint and the pathophysiology, imaging characteristics, and treatment options of rotator cuff tear arthropathy (RCTA). CONCLUSION: Although multiple pathways have been proposed as causes of RCTA, the exact cause remains unclear. Increasing knowledge about the clinical diagnosis, imaging features, and indicators of severity improves recognition and treatment of this pathologic condition.

Multimodality imaging of foreign bodies of the musculoskeletal system.

OBJECTIVE: The purpose of this article is to clarify the most relevant points in managing suspected foreign bodies of the musculoskeletal system on the basis of a literature review and published reports with cases to illustrate each type on different imaging modalities. CONCLUSION: Foreign bodies of the musculoskeletal system are a common problem in emergency departments, with more than a third missed in the initial clinical evaluation. These retained objects may result in various complications and also offer fertile ground for litigation.

Differential isotope-labeling for Leu and Val residues in a protein by E. coli cellular expression using stereo-specifically methyl labeled amino acids.

The (1)H-(13)C HMQC signals of the (13)CH3 moieties of Ile, Leu, and Val residues, in an otherwise deuterated background, exhibit narrow line-widths, and thus are useful for investigating the structures and dynamics of larger proteins. This approach, named methyl TROSY, is economical as compared to laborious methods using chemically synthesized site- and stereo-specifically isotope-labeled amino acids, such as stereo-array isotope labeling amino acids, since moderately priced, commercially available isotope-labeled α-keto acid precursors can be used to prepare the necessary protein samples. The Ile δ1-methyls can be selectively labeled, using isotope-labeled α-ketobutyrates as precursors. However, it is still difficult to prepare a residue-selectively Leu and Val labeled protein, since these residues share a common biosynthetic intermediate, α-ketoisovalerate. Another hindering drawback in using the α-ketoisovalerate precursor is the lack of stereo-selectivity for Leu and Val methyls. Here we present a differential labeling method for Leu and Val residues, using four kinds of stereo-specifically (13)CH3-labeled [U-(2)H;(15)N]-leucine and -valine, which can be efficiently incorporated into a protein using Escherichia coli cellular expression. The method allows the differential labeling of Leu and Val residues with any combination of stereo-specifically isotope-labeled prochiral methyls. Since relatively small amounts of labeled leucine and valine are required to prepare the NMR samples; i.e., 2 and 10 mg/100 mL of culture for leucine and valine, respectively, with sufficient isotope incorporation efficiency, this approach will be a good alternative to the precursor methods. The feasibility of the method is demonstrated for 82 kDa malate synthase G.

Spatial assessment of femoral neck bone density and microstructure in hip osteoarthritis.

Osteoarthritis (OA) is known to involve profound changes in bone density and microstructure near to, and even distal to, the joint. Critically, however, a full, spatial picture of these abnormalities has not been well documented in a quantitative fashion in hip OA. Here, micro-computed tomography (44.8 µm/voxel) and data-driven computational anatomy were used to generate 3-D maps of the distribution of bone density and microstructure in human femoral neck samples with early (6F/4M, mean age = 51.3 years), moderate (14F/8M, mean age = 60 years), and severe (16F/6M, mean age = 63.3 years) radiographic OA. With increasing severity of radiographic OA, there was decreased cortical bone mineral density (BMD) (p=0.003), increased cortical thickness (p=0.001), increased cortical porosity (p=0.0028), and increased cortical cross-sectional area (p=0.0012, due to an increase in periosteal radius (p=0.018)), with no differences detected in the total femoral neck or trabecular compartment measures. No OA-related region-specific differences were detected through Statistical Parametric Mapping, but there were trends towards decreased tissue mineral density (TMD) in the inferior femoral neck with increasing OA severity (0.050 < p ≤ 0.091), possibly due to osteophytes. Overall, the lack of differences in cortical TMD among radiographic OA groups indicated that the decrease in cortical BMD with increasing OA severity was largely due to the increased cortical porosity rather than decreased tissue mineralization. As porosity is inversely associated with stiffness and strength in cortical bone, increased porosity may offset the effect that increased cortical cross-sectional area would be expected to have on reducing stresses within the femoral neck. The use of high-resolution imaging and quantitative spatial assessment in this study provide insight into the heterogeneous and multi-faceted changes in density and microstructure in hip OA, which have implications for OA progression and fracture risk.

Inhibition of the SARS-CoV-2 helicase at single-nucleotide resolution.

The genome of SARS-CoV-2 encodes for a helicase called nsp13 that is essential for viral replication and highly conserved across related viruses, making it an attractive antiviral target. Here we use nanopore tweezers, a high-resolution single-molecule technique, to gain detailed insight into how nsp13 turns ATP-hydrolysis into directed motion along nucleic acid strands. We measured nsp13 both as it translocates along single-stranded DNA or unwinds short DNA duplexes. Our data confirm that nsp13 uses the inchworm mechanism to move along the DNA in single-nucleotide steps, translocating at ~1000 nt/s or unwinding at ~100 bp/s. Nanopore tweezers' high spatio-temporal resolution enables observation of the fundamental physical steps taken by nsp13 even as it translocates at speeds in excess of 1000 nucleotides per second enabling detailed kinetic analysis of nsp13 motion. As a proof-of-principle for inhibition studies, we observed nsp13's motion in the presence of the ATPase inhibitor ATPγS. Our data reveals that ATPγS interferes with nsp13's action by affecting several different kinetic processes. The dominant mechanism of inhibition differs depending on the application of assisting force. These advances demonstrate that nanopore tweezers are a powerful method for studying viral helicase mechanism and inhibition.

Hydrogen exchange study on the hydroxyl groups of serine and threonine residues in proteins and structure refinement using NOE restraints with polar side-chain groups.

We recently developed new NMR methods for monitoring the hydrogen exchange rates of tyrosine hydroxyl (Tyr-OH) and cysteine sulfhydryl (Cys-SH) groups in proteins. These methods facilitate the identification of slowly exchanging polar side-chain protons in proteins, which serve as sources of NOE restraints for protein structure refinement. Here, we have extended the methods for monitoring the hydrogen exchange rates of the OH groups of serine (Ser) and threonine (Thr) residues in an 18.2 kDa protein, EPPIb, and thus demonstrated the usefulness of NOE restraints with slowly exchanging OH protons for refining the protein structure. The slowly exchanging Ser/Thr-OH groups were readily identified by monitoring the (13)C(ß)-NMR signals in an H(2)O/D(2)O (1:1) mixture, for the protein containing Ser/Thr residues with (13)C, (2)H-double labels at their ß carbons. Under these circumstances, the OH groups exist in equilibrium between the protonated and deuterated isotopomers, and the (13)C(ß) peaks of the two species are resolved when their exchange rate is slower than the time scale of the isotope shift effect. In the case of EPPIb dissolved in 50 mM sodium phosphate buffer (pH 7.5) at 40 °C, one Ser and four Thr residues were found to have slowly exchanging hydroxyl groups (k(ex) < ~40 s(-1)). With the information for the slowly exchanging Ser/Thr-OH groups in hand, we could collect additional NOE restraints for EPPIb, thereby making a unique and important contribution toward defining the spatial positions of the OH protons, and thus the hydrogen-bonding acceptor atoms.

Alternative SAIL-Trp for robust aromatic signal assignment and determination of the χ(2) conformation by intra-residue NOEs.

Tryptophan (Trp) residues are frequently found in the hydrophobic cores of proteins, and therefore, their side-chain conformations, especially the precise locations of the bulky indole rings, are critical for determining structures by NMR. However, when analyzing [U-(13)C,(15)N]-proteins, the observation and assignment of the ring signals are often hampered by excessive overlaps and tight spin couplings. These difficulties have been greatly alleviated by using stereo-array isotope labeled (SAIL) proteins, which are composed of isotope-labeled amino acids optimized for unambiguous side-chain NMR assignment, exclusively through the (13)C-(13)C and (13)C-(1)H spin coupling networks (Kainosho et al. in Nature 440:52-57, 2006). In this paper, we propose an alternative type of SAIL-Trp with the [ζ2,ζ3-(2)H(2); δ1,ε3,η2-(13)C(3); ε1-(15)N]-indole ring ([(12)C (γ,) ( 12) C(ε2)] SAIL-Trp), which provides a more robust way to correlate the (1)H(ß), (1)H(α), and (1)H(N) to the (1)H(δ1) and (1)H(ε3) through the intra-residue NOEs. The assignment of the (1)H(δ1)/(13)C(δ1) and (1)H(ε3)/(13)C(ε3) signals can thus be transferred to the (1)H(ε1)/(15)N(ε1) and (1)H(η2)/(13)C(η2) signals, as with the previous type of SAIL-Trp, which has an extra (13)C at the C(γ) of the ring. By taking advantage of the stereospecific deuteration of one of the prochiral ß-methylene protons, which was (1)H(ß2) in this experiment, one can determine the side-chain conformation of the Trp residue including the χ(2) angle, which is especially important for Trp residues, as they can adopt three preferred conformations. We demonstrated the usefulness of [(12)C(γ),(12)C(ε2)] SAIL-Trp for the 12 kDa DNA binding domain of mouse c-Myb protein (Myb-R2R3), which contains six Trp residues.

Polymyxin-B hemoperfusion for acute exacerbation of idiopathic pulmonary fibrosis: serum IL-7 as a prognostic marker.

BACKGROUND: Acute exacerbation (AE) of idiopathic pulmonary fibrosis (IPF) has an extremely poor prognosis. Direct hemoperfusion with a polymyxin B-immobilized fiber column (PMX-DHP) has been used to improve oxygenation for acute respiratory distress syndrome. The study aim was to retrospectively determine the predictive factors affecting the prognosis of AE of IPF treated with PMX-DHP. METHODS: We studied patients suffering from AE of IPF, treated with PMX-DHP combined with high-dose corticosteroid therapy. Stored serum taken before and after PMX-DHP therapy was analyzed for 27 cytokines and chemokines. RESULTS: Nineteen patients with AE of IPF were studied. The median survival time after diagnosis of AE was 22 days. Survival rates after diagnosis of AE were 47.4% at 30 days, 31.6% at 60 days, and 26.3% at 90 days. Serum levels of Interleukin (IL)-7, an anti-fibrotic cytokine, in survivors at day 30 following PMX-DHP therapy ('Survivors') significantly increased after the treatment, compared to serum levels of non-survivors at day 30 after the therapy ('Nonsurvivors'), which did not demonstrate a significant change. Serum levels of IL-1beta, interferon-y and chemokine ligand (CCL) 2 levels were not significantly altered in 'Survivors', but were significantly changed in 'Nonsurvivors.' Multivariate Cox proportional-hazards analysis showed that an increase in IL-7 levels after PMX-DHP therapy and treatment without intubation (other than invasive positive-pressure ventilation) were significantly better prognostic factors. CONCLUSION: The results suggest that serum IL-7 may be a useful prognostic factor for patients with AE of IPF treated with PMX-DHP, possibly reflecting underlying anti-fibrotic mechanisms.

MRI-Detected Knee Ligament Sprains and Associated Internal Derangement in Athletes Competing at the Rio de Janeiro 2016 Summer Olympics.

PURPOSE: Describe the frequency and severity of knee ligament sprains diagnosed by MRI in athletes participating at the 2016 Summer Olympic Games, their association with certain sports and assess correlations with additional knee structural injury. PATIENTS AND METHODS: All knee MRIs performed in the Olympic Village and polyclinics during the 2016 Olympics were retrospectively, blindly reviewed for ligament sprains and associated knee injuries. In addition to the absence or presence of these abnormalities, athletes were stratified by age, gender and sport. RESULTS: 11,274 athletes participated in the 2016 Olympic Games: 113 athletes received at least one knee MRI with some having bilateral or repeat MRI on the same knee. Anterior cruciate and medial collateral ligament (ACL/MCL) sprains were most common, accounting for 32 of the 43 sprains (74.4%). Wrestling (10), hockey (7), athletics (7), and judo (5) accounted for over half of ligament sprains. ACL sprains showed a significant positive correlation with medial, lateral meniscal tears and bone contusions. The positive correlation between posterior cruciate ligament (PCL) sprains with MCL/lateral collateral ligament sprain, and popliteus tendon tear was statistically significant with 50% of total PCL sprains occurring in hockey. When athletes were stratified by gender, ligament sprains had a similar occurrence and distribution between men and women. CONCLUSION: Knee ligament sprains, at the Rio 2016 Games, were most common in wrestling, hockey, athletics and judo with ACL and MCL sprains most frequent. Meniscal tears and bone contusions occurred often with ACL sprains. PCL sprains tended to be multi-ligamentous injuries. Sustained ligament sprains had similar occurrence between genders, while men had a peak incidence of sprains at a younger age and women at an older age.

Application of SAIL phenylalanine and tyrosine with alternative isotope-labeling patterns for protein structure determination.

The extensive collection of NOE constraint data involving the aromatic ring signals is essential for accurate protein structure determination, although it is often hampered in practice by the pervasive signal overlapping and tight spin couplings for aromatic rings. We have prepared various types of stereo-array isotope labeled phenylalanines (epsilon- and zeta-SAIL Phe) and tyrosine (epsilon-SAIL Tyr) to overcome these problems (Torizawa et al. 2005), and proven that these SAIL amino acids provide dramatic spectral simplification and sensitivity enhancement for the aromatic ring NMR signals. In addition to these SAIL aromatic amino acids, we recently synthesized delta-SAIL Phe and delta-SAIL Tyr, which allow us to observe and assign delta-(13)C/(1)H signals very efficiently. Each of the various types of SAIL Phe and SAIL Tyr yields well-resolved resonances for the delta-, epsilon- or zeta-(13)C/(1)H signals, respectively, which can readily be assigned by simple and robust pulse sequences. Since the delta-, epsilon-, and zeta-proton signals of Phe/Tyr residues give rise to complementary NOE constraints, the concomitant use of various types of SAIL-Phe and SAIL-Tyr would generate more accurate protein structures, as compared to those obtained by using conventional uniformly (13)C, (15)N-double labeled proteins. We illustrated this with the case of an 18.2 kDa protein, Escherichia coli peptidyl-prolyl cis-trans isomerase b (EPPIb), and concluded that the combined use of zeta-SAIL Phe and epsilon-SAIL Tyr would be practically the best choice for protein structural determinations.

Knee cartilage damage and concomitant internal derangement on MRI in athletes competing at the Rio de Janeiro 2016 Summer Olympics.

PURPOSE: To report the MRI patterns of knee cartilage damage and concomitant internal derangement in athletes participating at the Rio de Janeiro 2016 Olympic Games. METHODS: Knee MRIs obtained at the core imaging facility of the International Olympic Committee were blindly, retrospectively reviewed by a board-certified musculoskeletal radiologist for meniscal, ligamentous, and tendon abnormalities. Cartilage assessment was based on the modified Outerbridge criteria. RESULTS: Of 122 athletes who received a knee MRI, 64 (52.4 %) had cartilage damage. Cartilage damage was more prevalent in the patellofemoral compartment (52 athletes, 42.6 %), followed by lateral (23 athletes, 18.9 %) and medial tibiofemoral compartments (12 athletes, 9.8 %). Patellofemoral cartilage damage was most prevalent in beach-volleyball (100 %), followed by volleyball (8 athletes, 66.7 %) and weightlifting (7 athletes, 70 %). Patellofemoral cartilage damage was most prevalent with quadriceps (8 athletes, 72.7 %) and patellar tendinosis (11 athletes, 61.1 %). Medial and lateral tibiofemoral cartilage damage was significantly associated with medial (8 athletes, 29.6 %) and lateral meniscal tears (16 athletes, 55.2 %), respectively. There was a trend for the percentage of athletes with cartilage damage to increase with age. CONCLUSION: The majority of athletes at the 2016 Rio Summer Olympics who had a knee MRI showed cartilage damage. Patellofemoral compartment cartilage damage was most common and frequently observed in certain sports including volleyball, beach volleyball, and weightlifting. Overuse in these sports can contribute to patellofemoral cartilage damage and subsequent development of anterior knee pain. Cartilage damage was also observed with concomitant meniscal tears and older age.

Solitary intramuscular myofibroma in an adult: Case report and MR imaging findings.

Myofibroma is a benign, soft tissue neoplasm that predominantly affects infants and young children. Most occur in the skin or subcutaneous tissues, with a predilection for the head and neck regions. We describe the magnetic resonance (MR) imaging and histophathologic findings of a rare case of intramuscular myofibroma of the right deltoid in a healthy 30-year-old male. MR imaging revealed a well-circumscribed intramuscular mass, with isointense signal on T1-weighted images, hyperintense signal on T2-weighed images, and a "target-sign" with peripheral rim enhancement after gadolinium administration. The lesion was surgically excised with no complications, and the histopathologic analysis revealed the typical morphologic and histochemical markers of a myofibroma. We conclude that, although rare, myofibroma can be considered in the differential diagnosis of adults with lesions the above signal characteristics.

Detection of vascular injuries in patients with blunt pelvic trauma by using 64-channel multidetector CT.

Vascular injuries are a major source of morbidity and mortality in patients with blunt pelvic trauma. Digital subtraction angiography (DSA) has traditionally been used to detect pelvic arterial injuries and to treat active arterial hemorrhage. Improvements in the technology of computed tomography (CT) have facilitated the implementation of CT angiography, which is beginning to replace DSA in the evaluation of patients with acute trauma. Pelvic CT angiography can reliably depict various pelvic arterial injuries and can help differentiate arterial hemorrhage from venous hemorrhage on the basis of multiphasic acquisitions, a method that may be used to tailor the subsequent clinical approach. With the use of a 64-channel multidetector CT scanner, multiphasic pelvic CT angiography can be integrated into the evaluation of trauma patients by using 1.25-mm reconstructed section thickness, pitch of 1:0.987, and gantry revolution time of 0.5 second to achieve near-isotropic results. A standard dose of 100 mL intravenous contrast material is injected at a rate of 5 mL/sec, and 30 mL saline solution, also at 5 mL/sec, is injected as a "chasing" bolus to follow the contrast material.

Active extravasation of the abdomen and pelvis in trauma using 64MDCT.

The objective of this study was to determine the clinical and management implications of the finding of active extravasation in blunt or penetrating trauma patients evaluated with abdomino-pelvic computed tomography (CT) using 64MDCT technology. This HIPAA compliant, retrospective study was IRB-approved, and the need for consent was waived. All adult patients scanned with 64MDCT who sustained blunt or penetrating abdomino-pelvic trauma and had findings of active extravasation at our Level I trauma center during a 30-month period were included. Two radiologists reviewed all abdomino-pelvic CT scans and characterized the active hemorrhage by location, extent, and attenuation on all available phases of imaging. Subsequent therapy and disposition were determined by reviewing the patients' medical records. The relationship between the location of a source of extravasation and subsequent clinical outcome was evaluated using Fischer's exact test. The relationship between the size and attenuation of the active hemorrhage and patient outcome were compared using the Wilcoxon rank sum test. One hundred and twenty-five patients with active extravasation were included. Patients with solid organ or pelvic injuries that were managed conservatively or had a negative digital subtraction angiogram had statistically significant smaller areas of active extravasation when compared to those that required intervention or died. When the attenuation values of extravasation are normalized to the intravascular attenuation achieved after intravenous contrast injection, no significant differences were seen based on subsequent clinical outcome. Based on location, those patients with solid organ, gastrointestinal/mesenteric, and pelvic sources of bleeding showed statistically significant higher likelihood of requiring subsequent intervention or dying, compared with those patients with subcutaneous, intramuscular, or retroperitoneal sources of active extravasation who were more likely to be managed conservatively (p < 0.0001, p = 0.005, p = 0.006, respectively). In blunt and penetrating trauma patients evaluated using 64MDCT technology, the location and size of the region of active extravasation are predictive of the type of subsequent clinical management. Normalized attenuation values of the active extravasation, however, are not predictive of subsequent management.