What’s New in Emergency Radiology? – March 2022

3 months ago

Diagnostic Accuracy of Ultrasound in Diagnosing Acute Appendicitis in Pregnancy: A Systematic Review and Meta-Analysis

 

Moghadam, M.N., Salarzaei, M. & Shahraki, Z. Diagnostic accuracy of ultrasound in diagnosing acute appendicitis in pregnancy: a systematic review and meta-analysis. Emerg Radiol (2022). https://doi.org/10.1007/s10140-022-02021-9

 

Clinical Question: What is the diagnostic accuracy of ultrasound for the diagnosis of acute appendicitis (AA) in the setting of pregnancy?

 

Methods: Systematic review and meta-analysis of 8 studies were included. Sensitivity and specificity of ultrasound in the diagnosis of AA in each trimester were compared to the gold standard of CT or surgical confirmation.

 

Results: The overall sensitivity was 77.6% and the overall specificity was 75.3% for the diagnosis of AA in pregnancy. Further breakdown by trimester showed sensitivity in the first, second, and third trimesters to be 69%, 63%, and 51%, respectively. The specificity by first, second, and third trimesters were 85%, 85%, and 65%, respectively.

 

Conclusion: Ultrasound diagnostic accuracy for the diagnosis of AA in pregnancy is low, especially in the third trimester, when perforation rate has also been reported to be 26.1%. Therefore, if ultrasound findings are negative or inconclusive, further diagnostic testing should be considered to prevent morbidity from AA, especially in the third trimester.

 

 

Accuracy of specific free air distributions in predicting the localization of gastrointestinal perforations

 

Celik, H., Kamar, M.A., Altay, C. et al. Accuracy of specific free air distributions in predicting the localization of gastrointestinal perforations. Emerg Radiol 29, 99–105 (2022). https://doi.org/10.1007/s10140-021-01990-7

 

Clinical Question: Can the distribution of free air accurately predict the location of gastrointestinal perforation?

 

Methods: Two independent radiologists retrospectively reviewed 115 cases to classify free air by location as perihepatic, periportal, perigastric, paraduodenal, perisplenic, mesenteric, omental, pelvic, or periappendiceal. Comparison was made to the intraoperative findings of sites of perforation.

 

Results: The distribution of free air correlated to the site of injury with the following associations (with most common cause in parentheses):

  • Periportal, perihepatic, perigastric – Gastroduodenal perforation (ulcer)
  • Mesenteric – Small bowel (trauma) and distal colon (diverticulitis)
  • Pelvic – Distal colon
  • Periappendiceal – Acute perforated appendicitis

 

The following table from the article shows the statistical analysis.

Location of free air n Location of perforation Sensitivity (%) Specificity(%) PPV (%) NPV (%) Accuracy(%) P-value
Perihepatic area 88 SD 86.4 40.3 58 75.8 62.8 0.001
Periportal area 51 SD 54.2 69.3 62.7 61.4 62 0.009
Perigastric area 82 SD 84.7 48.4 61 76.9 66.1 0.000
Mesentery 60 78.9 55.9 25 93.4 59.5 0.005
Mesentery 60 DC 81 57 28.3 93.4 61.2 0.002
Pelvis 33 DC 76.2 83 48.5 94.3 81.8 0.000
Peri-appendiceal 16 A 72.7 92.7 50 97.1 90.9 0.000

PPV, positive predictive value; NPV, negative predictive value; SD, stomach-duodenum; , jejunum-ileum; DC, distal colon; A, appendix vermiformis

 

Conclusion: The location of free air within the abdomen and pelvis has a statistically significant association with the site of perforation along the gastrointestinal tract. With this knowledge and the knowledge of the most common causes, suggestions can be made to possible site(s) of injury, which may result in differing treatment plans.

Improving Radiographic Fracture Recognition Performance and Efficiency Using Artificial Intelligence

 

Ali Guermazi, et al. Radiology 2021; 000:1–10 https://doi.org/10.1148/radiol.210937

 

Clinical Question: Can Artificial Intelligence (AI) improve fracture recognition and efficiency in both expert and non-expert readers?

 

Methods: A retrospective diagnostic study based on 480 cases with a 50% fracture prevalence, 60 from each body region, was performed with expert readers (musculoskeletal radiologists and orthopedic surgeons) and non-expert readers (emergency physicians, family medicine physicians, physician assistants, rheumatologists). Evaluation was performed both with and without AI assistance, with at least 1 month between evaluations. Sensitivity and specificity per patient was calculated for both with and without AI assistance.

 

Results: AI-assisted interpretation of fractures improved sensitivity by 10.4% without negative impact on specificity. Reading time was also decreased by approximately 6 seconds per examination. All body parts showed increased sensitivity except for the thoracolumbar spine, shoulder, and clavicle.

 

Conclusion: Fracture interpretation errors make up approximately 24% of diagnostic errors seen in the emergency department. Additionally, error rate increased during off hours (5 pm to 3am) and in cases of polytrauma. Assistance with AI technology not only may increase fracture detection and decrease interpretation time, but may also be used as a pre-screening aid to prioritize radiographs in the queue if a fracture may be present.

 

Stroke Mimics in the Acute Setting: Role of Multimodal CT Protocol

  1. Prodi, L. Danieli, C. Manno, A. Pagnamenta, E. Pravatà, L. Roccatagliata, C. Städler, C.W. Cereda, A. Cianfoni American Journal of Neuroradiology Feb 2022, 43 (2) 216-222

 

Clinical Question: Can multimodal CT (non-contrast CT head, CT angiogram, CT perfusion) reliably discriminate stroke mimics from acute ischemic strokes?

 

Methods: Retrospectively selected multimodal CT examinations during a 24 month period that had at least 1 followup imaging study. Comparison with the imaging diagnosis at the time of scan with the final clinical diagnosis at discharge.

 

Results: Of 401 patients investigated, a stroke mimic was diagnosed in 22% of studies. Stroke mimic diagnoses consisted of seizures (34.8%), migraine with aura attack (12.4%), conversion disorder (12.4%), infection (7.9%), brain tumor (7.9%), acute metabolic condition (6.7%), peripheral vertigo (5.6%), syncope (5.6%), transient global amnesia (3.4%), subdural hematoma (1.1%), cervical epidural hematoma (1.1%), and dural AVF (1.1%). Multimodal CT sensitivity, specificity, and accuracy were 24.7%, 99.7%, and 83%, respectively. CT perfusion demonstrated a pivotal role, detecting abnormalities in 95.5% of the stroke mimics diagnosed with multimodal CT.

 

Conclusion: Multimodal CT has a relatively low sensitivity rate to detect a stroke mimic in the setting of suspected stroke. However, it retains a high specificity which can support deferring revascularization with confidence if a stroke mimic is identified. CT perfusion specifically showed excellent ability to detect abnormalities in stroke mimics, notably including seizures, for which other CT examinations are diagnostically limited.

 

Vascular findings in CTA body and extremity of critically ill COVID-19 patients: commonly encountered vascular complications with review of literature

 

Lee, E.E., Gong, A.J., Gawande, R.S. et al. Vascular findings in CTA body and extremity of critically ill COVID-19 patients: commonly encountered vascular complications with review of literature. Emerg Radiol (2022). https://doi.org/10.1007/s10140-021-02013-1

 

This is a review article summarizing and illustrating COVID-19 vascular complications across the chest, abdomen, pelvis, and extremities. Background on the pathophysiology of the hypercoagulable state of COVID-19 (endothelial damage and cytokine storm) is discussed along with complications associated with anticoagulation therapy. According to the article, DVT and PE are by far the most common vascular findings. Pulmonary emboli are typically more peripheral than central with a prevalance ranging anywhere from 2 – 57%, with ICU patients demonstrating higher rates. DVT rates have been reported to be up to 13.7%, with CT venogram interestingly demonstrating a higher detection rate than Doppler ultrasound. The remainder of the vascular findings reviewed in the article include mycotic pseudoaneurysm, aortic thrombosis, mesenteric ischemia/infarction, solid organ infarct/bleeding, gastrointestinal bleed, intramuscular and retroperitoneal hematoma, peripheral arterial thrombosis, and catheter associated thrombosis.

 

 

CT of the Difficult Acute Aortic Syndrome

 

Kacie L. Steinbrecher, Kaitlin M. Marquis, Sanjeev Bhalla, Vincent M. Mellnick, J. Westley Ohman, and Constantine A. Raptis RadioGraphics 2022 42:1, 69-86

 

This Radiographics article reviews difficulties in the diagnosis of acute aortic syndrome on CT, displaying some subtle findings as well as discussing artifacts related to contrast administration. More commonly known diagnoses such as intramural hematoma and penetrating atherosclerotic ulcer are reviewed, as well as the more challenging and often nuanced diagnoses of limited intimal tear, aortic rupture, and shared sheath rupture. The importance of phase of contrast enhancement is emphasized, particularly in the detection of the false lumen and evaluation of its patency. The article also demonstrates how flow artifacts can simulate aortic dissection and discusses how to avoid this pitfall. Additional pitfalls regarding mediastinal hemorrhage and third spacing of contrast are discussed. The article also touches on the new Society for Vascular Surgery guidelines for describing acute aortic syndromes, which can provide more useful information for management purposes than the Stanford Type A/B classification alone.

 

 

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