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RSNA, Radiological
Society of North America:
Mark R. Wax, MD, Ingmar
Bitter, Stuart May, MD, Donald Wade, MD, Charlie Mazzarese
Summary:
Purpose: To
evaluate different types of bowel preparation to aid
in residual fluid tagging necessary for virtual colonoscopy
(VC) electronic cleansing.
Method
and Materials: 58 patients scheduled for virtual
colonoscopy underwent a daylong preprocedure bowel preparation
program of a low residue diet, low-density barium sulfate
suspension for stool tagging, laxatives of magnesium
citrate, bisacodyl tablets and suppository. To evaluate
residual fluid tagging, these patients were divided
into 3 groups. 16 patients in group (1) used 3 doses
of 40 cc of gastroview with meals the day prior to VC.
In groups (2) and (3), contrast was given in two doses,
at bedtime and in the morning, at least 1 ½ -
2 hours prior to VC using barium sulfate suspension
(2 % w/v, 250cc) for 18 patients and diatrizoate meglumine
and diatrizoate sodium solution (gastroview, 60cc) for
24 patients.
All patients underwent VC (120 kvp, 100mA/s,
5mm collimation, pitch 1.6-2.0, 1mm reconstruction intervals),
which included automatic electronic cleansing which
removes tagged residual fluid. Data recorded from the
axial images included Houndsfield values (HU) of residual
fluid in eight segments within the colon. The average
density and standard deviation were calculated. The
presence of remaining fluid at each segment following
electronic cleansing was determined. Electronic cleansing
was considered effective only if there was no remaining
fluid in all eight segments.
Results:
The average fluid density for group (1) was 97
HU (Std dev: 145); (2): 221 HU (Std dev: 182); (3):
599 HU (Std dev: 246). Group (3) differs statistically
significant from (1) and (2) with p-values of 0.0000000013
and 0.0000011. Prior to electronic cleansing, the total
number of segments with remaining fluid was (1): 91;
(2): 79; (3): 159. The number of segments cleansed was
5, 13, and 148 respectively. Effective electronic cleansing
occurred in 11%, 13% and 87% of each group.
Conclusion:
Only the use of bowel preparations with gastroview
given the evening before and morning of virtual colonoscopy
results in sufficient enhancement of residual fluid,
leading to effective automatic electronic colonic cleansing.
Keywords:
Virtual Endosocopy, Volume
Rendering, Interactive
Navigation, Complete Surface Coverage
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