Patients
Our study encompasses 20 cases (from September 2009 to August 2011),
selected according to the following criteria: tumoral lesions without a perspective of radical surgery due to invasion of a major arterial vessel (the celiac axis,
common hepatic artery,
hepatic artery,
superior mesenteric artery),
judged by MDCT,
in which the preoperative determination of unresectability was not confirmed during surgery (fig.3,
fig4.).
This group consisted of 14 men and 6 women with a mean age 59,6±2 years.
All patients underwent a preoperative contrast enhanced triphasic 64-slice and 256-slice multi-detector computed tomography (Phillips Brilliance).
Scanning Technique
The CT examinations were performed with multidetector row scanners.
Nine patients were examined using a 64-slice scanner (Brilliance 64 CT,
Philips Medical Systems (Cleveland)) and eleven patients,
a 256-slice scanner (Brilliance iCT,
Philips Medical Systems (Cleveland)). The examinations were performed according to the scan protocols in Table 1.
500 ml of water was routinely administrated 5-10 min before the examination to demarcate the duodenum and delineate the pancreatic head region.
Each patient received 100 ml of non-ionic contrast material 370 mg iodine/mL (omnipaque 350,
optiray 350) via intravenous injection at the rate of 3-4 ml/s by means of automatic power injectors (OptiVantage DH (Mallinckrodt; Inc.) through a 14-gauge intravenous catheter in a antecubital vein .
Unenhanced and triphasic (arterial phase,
venous phase and portal phase) enhanced scans were performed.
Unenhanced and enhanced scan images were obtained from the top of the diaphragm through the entire pancreas.
The obtained data sets were sent to a 3D Workstation (Easy Vision Philips).
This workstation was used for three-dimensional analysis of the local anatomy utilizing volume rendering (VR) combined with maximum intensity projection (MIP) and multiplanar reconstruction (MPR).
Window leveling was adjusted for each vessel to reach an optimal detection of its relationship to the tumor.
The evaluation of the CT scans was carried out by two radiologists in consensus prior to surgery to determine resectability.
Image analysis
For the assessment of pancreatic adenocarcinoma resectability,
we used generally accepted criteria (table 2.) This threshold has been shown to give good predictive values for resectability and unresectability [10].
MDCT findings were compared to surgical and pathology gold standards.
We considered radiological absence of a fat plane between tumor and artery with vessel wall irregularity as signs of possible invasion.
We defined "vascular invasion" as histological invasion of vessel wall by tumor,
"vascular encasement" as radiological circumferential involvement of more than 180 degrees of the artery,
and "vascular abutment" as tumor adjacency requiring vascular resection during surgery.
Lymph nodes were considered metastatic if the short-axis diameter was 1cm or larger [14].
Distant metastases and metastasis to lymph nodes beyond the field of resection,
as well as peritoneal involvement and hepatic metastasis indicated unresectability (fig.5.,fig.6).