We retrospectively reviewed the reports of all CEUS for gastrointestinal application in our Hospital performed between June 2006 and May 2012 to identify all patients with the terms “inflammatory mass”,
“phlegmon” or “abscess”.
US examinations were performed by using a US unit (Aplio 80; Toshiba,
Tokyo,
Japan) by three radiologists with wide experience in US of intestinal bowel diseases as well as in CEUS.
CEUS: Patients were examined with a 3-4 MHz convex probe in the wideband contrast harmonic mode (pulse inversion Toshiba Aplio) at low MI (MI<0.10).
The second generation echo-signal enhancer SonoVue® (Bracco,
Milan,
Italy) was injected as a bolus in units of 1.2ml through a three-way 20 gauge catheter into an antecubital vein,
immediately followed by injection of 10ml of normal saline solution (0.9% NaCl).
On US examination a phlegmon was considered as an ill-defined hypoechoic mass without identifiable wall and internal colour signals on colour Doppler.
On the other hand,
abscesses were diagnosed as hypoechoic fluid collections with an irregular wall and peripheral flow on colour Doppler.
Once the suspected areas were identified on baseline US and colour Doppler,
they were evaluated after second-generation contrast agent injection.
In CEUS study a diagnosis of phlegmon was made when intralesional enhancement was seen,
while abscesses showed absence of enhancement in the hypoechoic mass.
Phlegmon and/or abscess were confirmed by surgery,
CT,
MRI and/or percutaneous drainage within 2 weeks after CEUS.
A patient with inflammatory mass in two different intra-abdominal locations was considered twice.
When in the follow-up of a patient a new inflammatory mass was detected in a different localization it was considered as a new episode.
Two experienced abdominal radiologists with five years experience in CEUS retrospectively reviewed video sequences to calculate the interobserver agreement in assessing the diagnosis of phlegmon or abscess.
Basic descriptive statistics,
including the mean and standard deviation for continuous variables,
and the absolute frequency and percentage for discrete variables,
were used to characterize the study patients.
Variations in the size ofabscesses before and after contrast injection,
or between CEUS and CT or MRIwere analyzed using the Student t-test.
Agreement between CEUS diagnosis and the other techniques was established using the kappa statistics.The interobserveragreement for assessing the diagnosis of phlegmon or abscess was calculated bymeans of the exact percentage of agreement,
along with the kappa statistic.
All data were analyzed with Statistical Package for Social Sciences,
version 15.0.1 (SPSS Inc.,
Chicago,
IL,
USA).
For all tests,
p values less than 0.05 were considered to indicate a statistically significant difference.