While diagnosing chest pain is a complex problem for the emergency department physician, triple rule-out CT can be a powerful tool for evaluating and triaging patients with a low to moderate risk of acute coronary syndrome (ACS) where diagnostic catheterization is not indicated.

Triple-rule-out (TRO) CT angiogram of a 79-year-old woman with recent onset of vague chest discomfort. TRO CT demonstrates type B aortic dissection extending from distal aortic arch to the descending aorta. (a) Oblique slab maximum intensity projection (MIP) image shows the entire aortic arch with dissection flap extending into the abdomen. (b) Coronal slab MIP image again demonstrates the dissection with asymmetric enhancement of true and false lumina.

(Radiology 2009;252:332-345) © RSNA, 2009. All rights reserved. Printed with permission.

In a review article in the August issue of Radiology, (RSNA.org/Radiology), Ethan J. Halpern, M.D., of Thomas Jefferson University in Philadelphia, details how an optimized triple rule-out protocol provides excellent image quality for evaluating aortic and coronary and pulmonary arteries while minimizing contrast agent dose and radiation exposure. Specifically, the author addresses:

• The clinical role of triple rule-out CT

• Hardware and radiation issues

• Triple rule-out CT technique and image quality

• Patient selection, preparation and monitoring

• Setting up the triple rule-out scan

• Contrast agent injection and timing of image acquisition

• Image interpretation

"Triple rule-out CT precludes the need for additional diagnostic testing in more than 75 percent of patients with low to intermediate risk of ACS," Dr. Halpern concludes. "In a properly selected population, coronary CT can provide a cost-effective evaluation with reduced diagnostic time, lower costs, and fewer repeat evaluations for recurrent chest pain as compared with standard diagnostic evaluation."

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Appearance of Normal Cranial Nerves on Steady-State Free Precession MR Images

This article meets the criteria for 1.0 AMA PRA Category 1 Credit™.

Whereas traditional MR imaging sequences may lack the spatial resolution necessary to define smaller structures such as cranial nerves, steady-state free precession (SSFP) sequences allow much higher spatial resolution and clearer depiction of tiny intracranial structures.

Optic nerve.

Axial oblique 0.8-mm-thick steady-state free precession (SSFP) MR image shows three of four segments of the optic nerve: the retinal (black arrow), orbital (black arrowheads) and canalicular (white arrowhead) segments. The infundibulum of the pituitary gland (white arrow) is also seen. The fourth (cisternal) segment of the optic nerve would be visible on superior images.

(RadioGraphics 2009;29:1045–1055) © RSNA, 2009. All rights reserved.
Printed with permission.

In an article in the July-August issue of RadioGraphics (RSNA.org/radiographics), Sujay Sheth, B.A., Barton F. Branstetter IV, M.D., and Edward J. Escott, M.D., of the University of Pittsburgh School of Medicine, describe how SSFP sequences allow precise differentiation between branches of the facial and vestibulocochlear nerves, accurate detection of small masses in the cerebellopontine angles and internal auditory canals and detailed evaluation of the endolymph and perilymph within the inner ear.

Specifically the authors:

• Identify the expected course of each of the 12 cranial nerves

• Differentiate cranial nerves from other curvilinear structures visible on high-resolution MR images

• Describe pitfalls in the diagnosis of cranial nerve abnormalities

"SSFP sequences depict these nerve segments in greater detail and can provide important information about the relationship of the nerves to pathologic processes," the authors conclude.

"To take full advantage of this information, radiologists must be familiar with the expected nerve anatomy and relevant anatomic landmarks."

To access this RadioGraphics article now, click here.