RSNA News - December 2004

Journal Highlights

The following are highlights from the current issues of RSNA's two peer-reviewed journals.

Techniques and Applications of Automatic Tube Current Modulation for CT

Currently available automatic tube current modulation (ATCM) techniques can be used to maintain acceptable image quality while reducing radiation exposure on the basis of patient geometry and clinical indications.

In the December issue of Radiology (rsna.org/radiologyjnl), Mannudeep K. Kalra, M.D., D.N.B., from Massachusetts General Hospital and Harvard Medical School, and colleagues review the principles, clinical use and limitations of different ATCM techniques.

They write: "ATCM techniques represent an exciting recent technologic innovation toward radiation dose optimization. Further research is needed to standardize these techniques and define appropriate protocols for different patient sizes and indications."

This article also includes "Essentials" or highlighted points to help busy readers recognize important information at a glance.

A.
B.
Z-axis modulation with Real E.C. technique. (A) Attenuation is measured on a digital radiograph (left) and is converted to water-equivalent thickness (right), allowing user to specify image quality by choosing different noise levels. (B) After user selects tube current or, more appropriately, desired noise level for the examination (left), the software displays the automatic modulation of tube current that will be used to achieve selected image quality.

(Radiology 2004;233:649-657)
© 2004 RSNA. All rights reserved. Printed with permission.

Differential Diagnosis of Polypoid Lesions Seen at CT Colonography (Virtual Colonoscopy)

CT colonography, also referred to as virtual colonoscopy, holds significant promise for effective large-scale colorectal cancer screening. 2D and 3D displays of the CT data are employed, both of which are critical for proper evaluation. Although many radiologists continue to use the 2D images for polyp detection, more emphasis on the 3D images for primary detection of polyps has yielded the best results for screening detection.

In an article in the November-December issue of RadioGraphics (rsna.org/radiographics), Perry J. Pickhardt, M.D., from the University of Wisconsin Medical School in Madison and Uniformed Services University of the Health Sciences in Bethesda, Md., provides a variety of useful techniques and observations that can be used to increase the specificity of CT colonography for distinguishing false polyps from true polyps.

This article allows readers to:

• Provide a differential diagnosis for polypoid lesions seen at CT colonography.
• Describe techniques and findings that improve specificity for polypoid lesions seen at CT colonography.
• Discuss the diagnostic advantages and limitations for CT colonography as a colorectal screening tool.

Flat adenoma. (A) Endoluminal 3D view from CT colonography shows a relatively subtle flat lesion (arrowheads) near the anal verge. This adenoma was missed at prospective colonoscopy before the CT colonographic results were revealed. (B) Corresponding axial 2D image helps confirm a flat rectal lesion (arrow).

(RadioGraphics 2004; 1535-1559)
© 2004 RSNA. All rights reserved. Printed with permission.