Abstract Archives of the RSNA, 2003
Mannudeep Kalra MD, PRESENTER: Nothing to Disclose
Abstract:
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Purpose: Automatic tube current modulation (automA) represents a novel
technique that alters CT tube current to maintain a constant pre-selected image
quality. The purpose of this study was to compare image quality and diagnostic
acceptability of CT examinations of abdomen and pelvis acquired with automA and
fixed tube current technique.
Methods and Materials: 75 subjects (age = 19-84 years, mean age= 60 years, M:F=
42:33) underwent a follow-up CT examination of abdomen and pelvis with
multidetector row CT scanner (GE Lightspeed 4.X, Waukesha, WI) with 16
channels, using automA technique (noise index= 10.5-11.5, mA range= 10-380, 140
kVp, 5mm slice thickness). These examinations were compared with previous CT
scans performed with fixed tube current (200-300 mA, 140 kVp, 5mm slice
thickness). Two subspecialty radiologist graded the studies for image noise,
diagnostic acceptability and presence of any artifacts at superior aspect of
liver, porta hepatis, right kidney hilum, iliac crest and acetabulum using a 5-point
scale (1=unacceptable; 3=acceptable; 5=excellent). In addition, readers were
asked to record the abnormality seen on each study. Statistical analysis of the
data was performed using Wilcoxon signed rank test and kappa test of
inter-observer agreement.
Results: 77 lesions were detected in the study cohort comprising of 21 liver
masses, 14 with renal calculi, 12 adrenal masses, 12 uterine adnexal masses, 11
bowel masses and 7 gallstones. CT images acquired with automA technique did not
miss any lesion. Although, scores for image noise and diagnostic acceptability
were marginally lower for automA than fixed tube current at each level, these
changes were not statistically significant. Compared to fixed tube current
technique, both readers reported increased frequency and severity of beam
hardening artifacts at the level of superior aspect of liver with automA.
Conclusion: Despite an increased frequency of beam hardening artifacts with
automA technique compared to the fixed tube current technique, CT examinations
of abdomen and chest acquired using automA provides images with equal image
noise, diagnostic acceptability and lesion detection. (M.J. is an employee of
GE Medical Systems.)
Questions about this event email: mkalra@partners.org
Kalra MD, M,
Comparison of Automatic Current Modulation Technique with Fixed Tube Current CT Scanning of Abdomen and Pelvis. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3105597.html