Predicting Resectability of Pancreatic

Damien Olivié
1
, Luigi Lepanto
2
, Jean Sébastien Billiard
2
,
Pascale Audet
2
, Jessica Murphy Lavallée
2
1
Department of Radiology, University of Rennes Medical Centre. Rennes, France.
2
Department of Radiology, University of Montreal Medical Centre. Montréal, Québec, Canada
ABSTRACT
Context Computed tomography is widely
used to pre-operatively evaluate patients with
ductal carcinoma of the pancreas.
Objective To prospectively evaluate the
ability of multi-detector computed
tomography to predict resectability of
pancreatic head cancer.
Patients Ninety-one consecutive patients (53
men, 38 women; mean age, 61 years) referred
to our department with a diagnosis of cancer
of the head of the pancreas underwent a
preoperative contrast enhanced triphasic 16-
slice multi-detector computed tomography.
Sixty-three were considered inoperable
because of advanced local disease, metastatic
disease, or poor surgical risk.
Intervention Of the remaining 28 patients, 23
underwent a Whipple procedure, whereas 5
patients underwent a palliative procedure.
Main outcome measures Surgical and
pathologic reports were reviewed and
compared to CT results.
Results Of the 91 patients evaluated, 25%
had successful resection of pancreatic head
carcinoma; while only 5% had a palliative
procedure. When compared to surgical
outcome, the positive predictive value of
multi-detector computed tomography for
resectability was 100%. On the basis of
pathologic results, the positive predictive
value of multi-detector computed tomography
for resectability fell to 83%, Four patients
deemed resectable following multi-detector
computed tomography had positive margins at
pathology.
Conclusion The positive predictive value of
multi-detector computed tomography for
resectable disease is lower when pathologic
correlation, as opposed to surgical correlation,
is used as the gold standard. Compared to
previous studies, there was a lower rate of
palliative surgery in our cohort.
INTRODUCTION
Although pancreatic cancer accounts for only
2% of new cancers in the United States, it is
the fourth leading cause of cancer deaths. It
has an over-all 5-year survival rate of 4%,
while localized cancers have a survival rate of
17% [1]. About 15 to 20% of patients have
resectable disease at the time of presentation
[2]. Surgical resection offers the only chance
for cure with reported 5-year survival rates of
8% to 21% [3]. Tumors are considered
unresectable when metastatic disease or local
vascular invasion is present. The vessels most
often involved are the celiac trunk, the hepatic
artery, the superior mesenteric artery, as well
as, the superior mesenteric vein and the portal
vein [4, 5]. Contrast enhanced, helical

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computed tomography (HCT) and more
recently multi-detector computed tomography
(MDCT) have been widely accepted as the
imaging technique of choice for the staging of
pancreatic adenocarcinoma. Despite the
advent of endoscopic ultrasound, computed
tomography remains a mainstay of pre-
operative assessment [6, 7, 8]. The
introduction of helical CT, less than a decade
ago, improved our ability to appropriately
stage disease; however, a significant number
of patients are still incorrectly diagnosed as
having resectable tumor on CT only to be
unresectable at surgery. The proportion of
patients undergoing unnecessary laparotomy
may vary between 21% and 44% [5, 9, 10].
The purpose of this study is to evaluate,
prospectively, the ability of MDCT to predict
resectability of pancreatic cancer on the basis
of surgical outcome and pathologic
correlation.
MATERIALS AND METHODS
Patients
Between February 2003 and June 2004, 91
consecutive patients (53 men, 38 women;
mean age, 61 years; range, 36-83 years)
referred to our department with a known or
suspected diagnosis of cancer of the head of
the pancreas underwent a preoperative
contrast enhanced triphasic MDCT. Of the 91
patients, 63 (69.2%) were considered
inoperable because of advanced local disease,
metastatic disease, or poor surgical risk. The
remaining 28 patients (30.8%) formed the
basis for this study.
CT Technique
All examinations were performed with the
same 16 slice CT scan (Light speed, General
Electric Medical System, Milwaukee, WI,
USA). Patients drank 500 mL of water to
demarcate the duodenum and delineate the
pancreatic head region. All patients received
an intra-venous injection of 150 mL of
Omnipaque
®
350 (Amersham, GE Healthcare,
Oakville, Ontario, Canada) at a rate of 4 ml/s.
A triple-phase MDCT was then performed
with a detector width of 0.625 mm, a section
width of 2.5 mm and an interval
reconstruction of 1.25 mm. The scan delay
after the beginning of contrast infusion was
20 s for the arterial phase, 40 s for the late
arterial phase, and 60 s for the portal phase.
All images were interpreted on a picture
archiving and communication system (PACS)
workstation. Curved and multiplanar
reformations were obtained at a dedicated
post-processing workstation (Advantage
®
Windows 4.0, General Electric Medical
System, Milwaukee, WI, USA). MDCT scans
were analyzed prior to surgery to determine
resectability.
Image Analysis
Axial images, as well as, curved and
multiplanar reconstructions were reviewed.
Radiological criteria of unresectability
included: the presence of liver metastases,
peritoneal carcinomatosis, tumor infiltration
in contact with more than 180° of the
circumference of the walls of major arteries
(celiac trunk, hepatic artery, superior
mesenteric artery) and involvement of more
than 180° of the circumference of the portal
vein or the superior mesenteric vein. This
threshold has been shown to yield the best
predictive values for resectability and
unresectability [4, 5]. The MDCT findings
were correlated with surgical outcomes to
assess accuracy in predicting resectability.
Also, the pathologic reports were reviewed to
determine if the surgical margins were free of
tumor.
ETHICS
The study protocol conforms to the ethical
guidelines of the World Medical Association
Declaration of Helsinki, as revised in Tokyo
2004, and was approved by our institutions
Internal Review Board. Informed consent was
obtained from each patient participating in the
study.
DATA ANALYSIS
The accuracy and the positive and negative
predictive values for resectability of MDCT
were calculated by using surgical outcome as
a reference standard. The same parameters
were also calculated by using pathologic

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findings, particularly the presence or absence
of tumor infiltration at the surgical margins.
Frequencies, mean and range were used as
descriptive statistics.
RESULTS
The study group consisted of 28 patients.
There were 14 men and 14 women, with
average ages of 63 years (range 40-76 years).
Twenty-three underwent a Whipple
procedure, whereas 5 patients underwent a
palliative procedure. The interval between
MDCT and surgery was 22.4 days (range 3-
55 days). Surgical and pathologic reports
were reviewed and compared to CT results.
Correlation with surgical findings was
available in 28 patients, whereas correlation
with pathologic findings was available in 23
patients. The diameter of the lesions in these
patients ranged from 1.2 to 3.6 cm. The
average lesion diameter was 2.2 cm. Table 1
summarizes the correlation between MDCT
findings, and surgical and pathologic findings.
When compared to surgical outcome, the
positive predictive value of MDCT for
surgically resectable disease was 100%
(23/23), and the negative predictive value i.e.
(prediction of unresectability) was also 100%
(5/5). Accuracy was 100% (28/28). Four of
the 23 patients who underwent a Whipple
procedure and were believed to be resectable
on the basis of MDCT were found to have
positive surgical margins at pathology. On the
basis of pathologic results, therefore, the
positive predictive value of MDCT for
resectability fell to 82.6% (19/23). Two of the
4 patients with positive margins had
infiltration of the root of the mesentery and
tissue abutting the superior mesenteric artery.
In both cases, less than 180° of the vessel
circumference was involved. Follow-up scans
obtained within 4 months of surgery in both
these patients showed local recurrence of
tumor (Figure 1).
DISCUSSION
The accurate determination of resectability in
patients with pancreatic cancer is the most
important contribution of pre-operative
staging; the goal being to reduce needless
Table1. Local resectability at MDCT correlated with surgical outcome and pathologic results.
Surgical outcome
Pathologic results
Total
(No. 28)
Resected
(No. 23)
Palliative
(No. 5)
Total
(No. 23)
Free margins
(No. 19)
Positive margins
(No. 4)
CT resectable
23
23 (100%)
-
23
19 (100%)
4 (100%)
CT unresectable
5
-
5 (100%)
0
-
-
Figure 1. Adenocarcinoma of the head of the pancreas
in a 71-year-old man. a. Arterial phase, transverse
MDCT image, obtained during pre-operative staging,
shows tumor infiltration (arrow) abutting the posterior
wall of the superior mesenteric artery (arrowhead). b.
Portal phase, transverse image MDCT, shows tumor
recurrence (arrow) at the site of previous surgery, near
surgical clips (arrowhead).

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surgery to a minimum. Laparotomy in
patients with pancreatic cancer carries
significant perioperative morbidity (20-30%),
even in expert hands [11]. Moreover,
prognosis is not improved for patients whose
tumors are resected with positive margins or
vascular invasion [12, 13]. On the other hand,
for most patients with unresectable lesions,
laparotomy for palliative procedures has
become unnecessary because of recent
advances in endoscopic and percutaneous
methods of biliary and duodenal
decompression.
The improvement in CT technology has been
paralleled by an improvement in the ability of
CT to predict resectability. In a meta-analysis,
Bipat et al. found a sensitivity and specificity
of HCT for determining resectability of 81%
and 82%, respectively [14]. This represented
a significant improvement over conventional
CT. Predictive values of HCT for resectability
ranging from 56% to 79% have been reported
[5, 9, 10, 15, 16]. Most of these studies
reported better results when predicting
unresectability, with predictive values ranging
from 96% to 100%. Only Phoa et al. found a
predictive value for unresectability of 57%,
well below that found by other investigators
[16]. In a recent study evaluating the ability of
MDCT to detect resectability, Vargas et al.
reported a predictive value for resectability of
87% [17]. This represents a further
improvement over HCT. Our results show a
predictive value of 100% for resectability
when compared to surgical outcome. The rate
of patients who underwent resection of
pancreatic adenocarcinoma was higher in our
study; in fact, only 5% of all patients
evaluated by MDCT in our study eventually
had a palliative surgical procedure. With so
few patients deemed unresectable on the basis
of MDCT submitted to surgery, it is difficult
to evaluate the predictive value for
unresectability.
Comparing CT results to pathologic findings
modifies the results somewhat. When the
absence of positive margins is considered the
requirement for successful resection, the
positive predictive value of MDCT for
resectability fell to 83%. Similarly, Phoa et al.
also showed an increase in the predictive
value for unresectability (from 57% to 82%)
and a decrease in the predictive value for
resectability (from 72% to 50%), when
pathologic, rather than surgical, correlation
was considered [16].
The proportion of patients submitted to
surgery whose pancreatic adenocarcinoma
was successfully resected was 82% in our
series. In the series reported by Vargas et al.,
the resection rate was 80% [17]. The advent
of MDCT has seen an increase in the rate of
successful resection of pancreatic cancer in
patients submitted to surgery. In previously
published series using HCT, the resection rate
varied between 28% and 73.5% [5, 9, 10, 15].
In the study published by Phoa et al., using a
twin detector HCT, the resection rate was
57% [16].
Our study does present some limitations. No
instances of small liver metastases were seen
at laparotomy in cases with CT resectable
disease. There is no clear explanation for this;
possibly, the detection of early local invasion
such as infiltration surrounding the superior
mesenteric artery and accompanying
infiltration of the root of the mesentery,
precede peritoneal seeding and small liver
metastases. Also, a detailed analysis of why
63 of 91 patients initially assessed were
deemed inoperable was not carried out,
because there is no way to correlate the CT
findings with accurate staging. However, the
19 patients who had their cancers successfully
resected, in our study, represented 21% of all
patients initially evaluated. This correlates
well with findings in the literature, reporting
that only 15 to 20% of patients have
resectable disease at the time of presentation
[2]. In our institution, venous resection is not
routinely performed during Whipple
procedure. This technique is used in certain
centers and thus the criteria for resectability
will necessarily differ from the ones used in
our study.
In conclusion, there is improved prediction of
resectability and unresectability with the
introduction of MDCT. When compared to
HCT studies, there is a rise in the rate of
successful surgical resection with a

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concomitant decrease in the rate of palliative
surgery, leading to a difficulty in measuring
the predictive value of unresectability since
fewer patients with unresectable disease
undergo laparotomy.
Received September 2
nd
, 2007 - Accepted
September 28
th
, 2007
Keywords Carcinoma, Pancreatic Ductal;
Pancreas; Pancreatic Neoplasms; Surgery;
Tomography, Spiral Computed; Tomography,
X-Ray Computed
Abbreviations HCT: helical computed
tomography;
MDCT:
multi-detector
computed tomography
Conflict of interest The authors have no
potential conflicts of interest
Correspondence
Luigi Lepanto
Centre Hospitalier de l’Université de Montréal
Department of Radiolgy
1058 rue Saint Denis
Montréal, Québec
Canada H2X 3J4
Phone: +1-514.890.8350
Fax: +1-514.412.7359
E-mail: luigi.lepanto@umontreal.ca
Document URL: http://www.joplink.net/prev/200711/12.html
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