Keywords
Endoscopic ultrasound - multidetector CT - pancreas
Introduction
Pancreatic masses are commonly seen and present with similar clinical presentation,
hence their differentiation dictates their management.
Multidetector computed tomography (MDCT) provides 3-D multiplanar reconstruction with
improved spatial and temporal resolution enabling accurate determination of tumor
involvement of the common bile duct (CBD), pancreatic duct, and peripancreatic vasculature.[1] It also enables the detection of metastasis and loco-regional spread in cases of
pancreatic carcinoma.
Endoscopic ultrasound, overcomes the limitations of transabdominal USG and has shown
to be more sensitive than MDCT for visualization of pancreatic tumors <3 cm in size
and allows concurrent biopsy.[2], [3] However, it is highly operator dependent.[4], [5]
Our aim was to compare the role of CT and EUS in the evaluation of pancreatic masses
and define their complementary roles if any.
Subjects and Methods
A cross-sectional, prospective study to evaluate pancreatic lesions using MDCT and
Endoscopic USG along with Endoscopic USG guided FNAC/cyst aspiration was undertaken
at our institute. Patient recruitment was done prospectively from May 2015 to January
2017. The study was approved by the Institutional Ethics Committee, and informed consent
was taken from all the patients. Patients (≥10 years) with clinical (history, examination,
serum markers like CA 19-9 in cases of pancreatic adenocarcinoma, C-peptide and insulin
levels for neuroendocrine tumors particularly insulinomas) suspicion of pancreatic
mass and/or incidentally discovered pancreatic mass on any imaging modalities, like
transabdominal ultrasound, CT abdomen or MRI abdomen were included. Exclusion criteria
were pregnant females, contraindications to contrast enhanced CT examination and patients
unable to undergo endoscopic ultrasonography for any reason.
Thirty-six patients were included in the study, who underwent contrast enhanced MDCT
and Endoscopic ultrasound for characterization of pancreatic lesions (14 men, 22 women;
age range 10–70 years). The interval between MDCT and Endoscopic ultrasound examinations
was less than 2 weeks. A detailed clinical history was taken. Clinical findings, General
physical examination, abdominal examination, laboratory investigations of all the
patients were recorded. Clinical diagnosis was recorded. Findings on other imaging
modalities done prior to CT abdomen and Endoscopic ultrasound were also recorded.
This was followed by CT examination on 256-slice dual source multidetector CT and
endoscopic ultrasound (EUS) with formulation of a CT diagnosis and EUS diagnosis.
FNAC/ cyst aspiration (in case of cystic lesions) wherever required and feasible was
performed. These findings were compared with histopathological diagnosis/operative
diagnosis/clinical follow up to arrive at the final diagnosis
Procedure for MDCT
All patients undergoing abdominal CT were instructed for overnight fasting. NCCT and
CECT were acquired using a set protocol on Dual source 256 slice MDCT (Somatom Definition
FLASH). Each patient was scanned from diaphragm to the pubic symphysis. Scans were
obtained with a slice thickness of 1.5mm, at 120 kV and 250 effective mAs. Contrast
enhanced CT scans were obtained using dual phase pancreatic imaging protocol comprising
pancreatic parenchymal (at 35-40 seconds from start of I/V contrast) and portal venous
phase (at 65-70 seconds from start of I/V contrast). Ninety to one hundred twenty
millilitre of non-ionic iodinated contrast media (iodine 320 mgI mg/mL) was injected
through an intravenous cannula using a pressure injector (at rate of 4 mL/s). Post
processing of the axial data set was done and images were preserved in axial, coronal,
sagittal and relevant MPR format. MIP format and VRT images were generated wherever
deemed appropriate. CT images were reviewed by two radiologists who recorded their
findings arrived at by common consensus on a predefined proforma.
Procedure for EUS
After overnight fasting the patient was taken for EUS procedure. An IV line was secured,
all procedures were done under mild sedation using midazolam, 1–2.5 mg slow IV, under
the supervision of a doctor.
All procedures were done by linear Olympus CLV 180 series scope (Olympus Corporn.,
Japan) with high-frequency transducer (5–13 Mhz) using station approach in the left
lateral position. A transgastric approach was used to depict the pancreatic neck,
pancreatic body and tail, splenic vein, whereas a transduodenal approach was used
to reveal the pancreatic head, common bile duct, and portal vein and its confluence.
The uncinate process, superior mesenteric artery, and superior mesenteric vein were
seen using the second and third portions of the duodenum as an ultrasound window.
All parameters regarding tumor size, location, the involvement of vessels, were recorded
in the prescribed format. The whole of pancreas was evaluated. FNAC (via transduodenal
route for pancreatic head and body lesions and via transgastric route for pancreatic
tail lesions) was done using Echotip ultra 22 G needle (Cook Corporn.) and was evaluated
by on- site pathologist.
After the procedure, the patient was monitored in recovery room for 4–6 h.
Statistical test used
Excel software was used to analyze the statistical data. Descriptive statistics with
percentages and proportions of the occurrence of pancreatic masses were generated
for the study patients according to age and sex, location of lesions, morphology of
lesions, characterization of lesions using MDCT study and EUS study, comparison of
MDCT and EUS in characterization of pancreatic lesions individually and with combined
use of both modalities (MDCT and EUS). Comparison of MDCT and EUS in determining operability
of pancreatic ductal carcinoma (based on MD Anderson’s resectability criteria for
pancreatic malignancy[6]) was done using 2x2 contingency table with calculation of sensitivity, specificity,
PPV, NPV and the P value using Chi-square test.
Results
A total of 36 patients were included in the study. Each of the patients included were
subjected to an abdominal MDCT scan on a 256-slice scanner followed by a EUS examination.
The occurrence of pancreatic lesion, solid/solid cystic/cystic was seen to be more
common in the females compared to males with a male is to female ratio of almost 1:1.5
in our study.
The pancreatic lesions including both malignant and benign masses were seen to occur
most commonly in the 4th to 6th decades of life.
The most common site of occurrence of pancreatic masses was the pancreatic head region,
with few lesions showing multiple sites of occurrence.
The pancreatic lesions encountered could be broadly classified as solid masses (n = 26), cystic masses (n = 8), and mixed solid-cystic masses (n = 2).
Amongst all cases of pancreatic masses, pancreatic adenocarcinoma emerged as the single
most common pancreatic lesion.
The cystic lesions of the pancreas were relatively less common in occurrence compared
to solid lesions, with nearly equal proportions of serous cystadenoma, mucinous cystadenoma,
and intraductal papillary mucinous neoplasm encountered in our study.
Characterization of Pancreatic lesions on MDCT in comparison to final diagnosis:
It was noted that in 88% of cases of solid lesions encountered, MDCT diagnosis was
consistent with the final tissue diagnosis. This percentage was 62% for cystic lesions,
with 100% solid-cystic lesions being correctly diagnosed on MDCT [Table 1].
Table 1
Characterization of pancreatic lesions on MDCT in comparison to final diagnosis. Out
of total 36 cases
|
Pancreatic lesions
|
Consistent with final diagnosis
|
Inconsistent with final diagnosis
|
Inconclusive
|
|
Lesions
|
Number
|
Number
|
Percentage
|
Number
|
Percentage
|
Number
|
Percentage
|
|
*2 cases were inconclusive on CT
|
|
Solid
|
26
|
23
|
23/26=88
|
2
|
2/26 = 7
|
1
|
1/26=4
|
|
Cystic
|
8
|
5
|
5/8=62
|
2
|
2/8=25
|
1
|
1/8 = 13
|
|
Solid-cystic
|
2
|
2
|
2/2 = 100
|
0
|
0
|
0
|
|
|
Total
|
36
|
30/36
|
|
4/36
|
|
2/36
|
|
CT findings were considered ‘inconclusive’ in the setting of findings such as focal
enlargement and fullness of the pancreas and dilatation of the pancreatic duct without
evidence of an underlying mass.
Characterization of Pancreatic lesions on EUS in comparison with the final diagnosis
When comparing the results of EUS with tissue diagnosis, it was found that the diagnosis
of EUS was consistent with gold standard tissue diagnosis in 73% of solid lesions,
38% of cystic lesions with none of the solid-cystic lesions being consistent with
tissue diagnosis [Table 2].
Table 2
Characterization of pancreatic lesions on EUS in comparison with the final diagnosis.
Out of total 36 cases
|
Pancreatic lesions
|
Consistent with final diagnosis
|
Inconsistent with final diagnosis
|
Inconclusive
|
|
Lesions
|
Number
|
Number
|
Percentage
|
Number
|
Percentage
|
Number
|
Percentage
|
|
*10 cases were inconclusive on EUS
|
|
Solid
|
26
|
19
|
19/26 = 73
|
1
|
1/26=3
|
6
|
6/26=23
|
|
Cystic
|
8
|
3
|
3/8=38
|
2
|
2/8=25
|
3
|
3/8=37
|
|
Solid-cystic
|
2
|
0
|
0
|
1
|
1/2=50
|
1
|
1/2=50
|
|
Total
|
36
|
22/36
|
|
4/36
|
|
10/36
|
|
EUS findings were considered ‘inconclusive’ in the setting where the lesion was categorized
based on imaging morphology as cystic/solid/solid cystic with no definitive diagnosis.
Comparison of multidetector computed tomography and Endoscopic ultrasound imaging
in assigning definitive diagnosis
The number of cases correctly diagnosed with MDCT when compared against the gold standard
histopathological diagnosis were 30, with percentage of 83%, and with EUS were 22,
with percentage of 61%. The number of lesions categorized as inconclusive were less
for MDCT compared to EUS, 2 Vs 10 in number [Table 3].
Table 3
Characterization of pancreatic lesions on MDCT and EUS: Out of the total 36 cases
|
MDCT
|
EUS
|
|
Number
|
Percentage
|
Number
|
Percentage
|
|
Consistent with final diagnosis
|
30
|
83
|
22
|
61
|
|
Inconsistent with final diagnosis
|
4
|
11
|
4
|
11
|
|
Inconclusive
|
2
|
6
|
10
|
28
|
|
Total
|
36
|
100
|
36
|
100
|
|
Consistent with final diagnosis
|
30
|
83
|
22
|
61
|
Comparison of characterization of masses by individual and combined use of modalities
The best results for characterizing the pancreatic lesions were obtained with combined
use of all modalities, MDCT, Endoscopic ultrasound imaging along with Endoscopic ultrasound
guided intervention, with a percentage correct diagnosis of nearly 95% (34/36 cases).
The same percentage for MDCT imaging alone was 83%, EUS imaging alone was 61% and
MDCT and EUS imaging was 86% [Table 4].
Table 4
Characterization of masses by individual and combined use of modalities: Out of total
36 cases
|
Modality
|
Cases consistent with final diagnosis
|
|
Number
|
Percentage
|
|
EUS Imaging
|
22
|
61
|
|
MDCT imaging
|
30
|
83
|
|
MDCT + EUS imaging
|
31
|
86
|
|
MDCT + EUS imaging + EUS -FNA/CYST aspiration
|
34
|
95
|
Assessment for operability of Pancreatic adenocarcinoma
The main thrust of our study was detection and characterization of pancreatic lesions,
however, a small subset of cases of pancreatic adenocarcinoma was assessed for resectability
on both MDCT and endoscopic ultrasound, as both these modalities contribute significantly
in determining tumor operability. Cases of pancreatic adenocarcinoma in our study
were assessed for their resctability status based on the MD Anderson’s resectability
criteria for pancreatic malignancy, with vessel involvement being assessed on axial
sections using grading system proposed by Raptopoulos et al.[7]
[Figure 1] and classified into resectable, borderline resectable, and unresectable according
to it. Our study showed that out of the sixteen cases of pancreatic malignancy presenting
to us only four cases were found to be resectable at the time of presentation and
rest twelve were unresectable, with none in the borderline resectablity category [Tables 5] and [6].
Figure 1: Raptopoulos et al. grading of vessel involvement
Table 5
Pancreatic adenocarcinoma
|
Pancreatic adenocarcinoma
|
Number
|
Percentage
|
|
Resectable
|
4
|
25
|
|
Unresectable
|
12
|
75
|
|
Total
|
16
|
100
|
Table 6
Assessment of resectabilty of pancreatic adenocarcinoma on MDCT and EUS
|
Peroperative
|
Total
|
|
Unresectable
|
Resectable
|
|
MDCT
|
|
|
|
|
Unresectable
|
12
|
0
|
12
|
|
Resectable
|
0
|
4
|
4
|
|
EUS
|
|
|
|
|
Unresectable
|
12
|
1
|
13
|
|
Resectable
|
0
|
3
|
3
|
|
Total
|
12
|
4
|
16
|
MDCT
Sensitivity=12/12x100=100 % Specificity=4/4x100=100%
PPV= 12/12 x100=100%NPV=4/4x100=100%
EUS
Sensitivity=12/12x100=100% Specificity=3/4x100=75%
PPV= 12/13x100=92.30% NPV= 3/3x100=100%
The above findings concluded for our study that MDCT has higher specificity and PPV
in determining resectability of pancreatic adenocarcinomas as compared to EUS, with
sensitivity and NPV being similar for both modalities.
The P-value equals 0.66 using Chi-square test, which is not statistically significant.
Discussion
Pancreatic masses represent a myriad of pathologies, ranging from benign to malignant.
Amongst the malignant masses, the early detection of pancreatic ductal adenocarcinoma
is of prime importance as early detection and diagnosis can greatly influence its
resectability status. The 5-year survival rate in resectable tumors have been found
to be as high as 20%–25%, compared to unresectable tumors, very few of whom survive
5 years after diagnosis.[7]
Cystic pancreatic neoplasms are rare entities, however, advancement in cross-sectional
imaging techniques like MDCT, have led to an increase in the detection of these lesions.
It is important to characterize these lesions as their management guidelines vary
greatly. Mucinous cystic lesions are considered premalignant. Hence, surgery is recommended
for all mucinous neoplasms and symptomatic cystic lesions.
As the pancreatic masses have a significant overlap in their clinical presentation,
the role of imaging assumes a pivotal position in the management of pancreatic masses.
There is a need for a systematic approach towards cases suspected with any pancreatic
pathology.
Whenever a pancreatic mass is suspected on Pre MDCT and Pre EUS work up of patient,
the next steps are, detection of the lesion on MDCT/EUS, characterization of the lesion
and lastly to determine the extent of the disease (locoregional and distant spread
of disease).
In our study, we found that the detection of a mass lesion on MDCT greatly depended
on the size of the lesion. The sensitivity of CT in the detection of pancreatic cancers
lies between 75%–100%.[8] For tumors >2 cm the sensitivity may be as high as 98%.[9] EUS has emerged as a useful, albeit invasive, modality in the diagnosis of pancreatic
tumors with sensitivities and accuracy approaching 100% and specificity >95% even
for lesions <2 cm in size.[9] In the current scenario, a CT scan is still recommended as the first-line imaging
modality to detect pancreatic lesions but in event of negative results with CT scan,
EUS (when available) is indicated to confirm the absence of small pancreatic lesions.
The early detection of a lesion is critical in the cases of pancreatic adenocarcinomas
as it has been found that the size of the pancreatic tumor is a major determinant
of resectability with up to 83% of tumors ≥20 mm being resectable compared to only
7% of tumors >30 mm in size.[7], [10]
Diagnosis of pancreatic neoplasm is challenging in patients with inconclusive findings
on pancreatic multidetector CT. In a recent article ‘ Use of EUS-FNA in diagnosing
pancreatic neoplasm without a definitive mass on CT’, Wei Wang et al mention that in setting of ‘negative findings’ or ‘non-specific’ CT findings such
as solely focal enlargement, fullness of the pancreas and dilation of the pancreatic
duct without evidence of an underlying mass, further diagnostic work up is required.[12] The next important step in pre-operative work up is characterization of the mass
lesion based on their imaging morphology. With new age multidetector CT scanners which
provide very thin slice cuts, high image resolution and fast acquisition, majority
of the pancreatic lesions can be accurately characterized on MDCT alone. In our study
the diagnosis made on MDCT was consistent with the final pathological diagnosis in
83% of the cases. Opposed to this the EUS diagnosis was consistent with final tissue
diagnosis in 61% of the cases. EUS alone (without FNA) was unable to characterize
the lesions in a large number of cases of our study and these were categorized as
inconclusive.
The necessity of tissue acquisition by FNA during the evaluation of pancreatic masses is dependent on the clinical scenario
and institutional practices. The tissue sample can be obtained either via a percutaneous
route under CT/USG-guidance or endoscopically via EUS. The percutaneous approach is
often risky with chances of bowel and vessel injury.
Endoscopic ultrasound has been shown to be a valuable imaging tool for the detection of pancreatic lesions.
Additionally, EUS has a capability to perform fine-needle aspiration and provide concurrent
tissue diagnosis at the time of EUS that has made it an essential tool in the diagnostic
algorithm of solid pancreatic lesions. In cases of unresectable lesions, tissue diagnosis
by FNA before committing patients to chemotherapy and/or radiation therapy is essential.
The advantage of EUS-guided FNA over percutaneous FNA lies in the trans-duodenal approach
for FNA in endoscopic EUS. The needle tract is along the tissues that would subsequently
be resected in pancreaticoduodenectomy, thereby significantly lowering the risk of
tumor seeding along the needle tract. The endoscopic US is also an optimal method
for lymph node staging.
Owing to the morbidity associated with a surgical exploration, the pre-operative work
up in case of pancreatic adenocarcinoma includes classifying the tumor as resectable
vs borderline resectable vs unresectable. According to Brennan et al.[13] only a small percentage of patients, about 5-30% with pancreatic tumors have resectable
tumors at the time of presentation. Our study analyzed a total of 16 cases of pancreatic
adenocarcinoma, out of which only a small percentage, 25% were resectable at time
of presentation.
The CT report of cases with suspected pancreatic adenocarcinomas conveyed information
regarding, presence or absence of a primary tumor in the pancreas; presence or absence
of peritoneal and hepatic, nodal metastases; description of the patency of the superior
mesenteric vein-portal vein confluence and the relationship of these veins to the
tumor; description of the relationship of the tumor to the superior mesenteric artery
(SMA), celiac axis, and hepatic artery and any vascular anatomic variants. The major
advantage of CT in comparison with EUS is its ability to provide an assessment of
the entire abdominal cavity thus providing more information than EUS for distant metastases.
Another important dimension to preoperative imaging is assessment of major vascular
structures, for both evaluation of resectability and also regarding aberrant anatomy.
EUS has proven to be more accurate in detecting portal vein or splenic vein invasion,
with accuracy of 78-98%, especially in the area of portal confluence. MDCT is superior
in detecting arterial invasion over a broader area, particularly in the region of
superior mesenteric artery with a sensitivity rate at 71% versus that of 57% by EUS.[14] In our study the sensitivity, specificity, PPV and NPV of MDCT and EUS were compared
[Table 6] with each other keeping peroperative findings as gold standard in determining 16
cases of pancreatic adenocarcinomas as resectable or unresectable or borderline resectable.
We found that MDCT is superior to EUS in assessing tumor resectability preoperatively.
EUS being an invasive modality compared to the non-invasive MDCT has certain potential
risk of complications associated with it along with few technical disadvantages. EUS
carries a 0.1-1% risk of pancreatitis.[6] The most dreaded complication with EUS is perforation which is very rare. As EUS
requires the probe to be positioned in the duodenum for optimal evaluation, there
can be technical difficulties as well as patient non- compliance for the same.
MDCT vs EUS
Case 1
The MDCT of a 48-year female who presented with an initial complaint of abdominal
pain showed a contour irregularity within the body of the pancreas with no definite
mass. The “fullness” was also noted to be isodense with the pancreatic parenchyma
on all phases. A subsequent EUS of the patient revealed a well-defined hypoechoic
mass showing internal vascularity. The mass was confirmed to be a neuroendocrine tumor
on the histopathological diagnosis. EUS has an invaluable role in cases where MDCT
shows no definite mass [Figure 2].
Figure 2 (A-E): Axial CT pancreatic parenchymal (A), venous phase (B) and thin MIP (C) images showing
contour deformity/‘fullness’ (arrow) in body of pancreas, isodense on all phases.
CT findings were inconclusive. EUS (D) showed a well-defined hypoechoic mass (arrow)
in body of pancreas with internal vascularity. EUS guided FNA (E) Photomicrograph
(H&E 220X) showed cells with eosinophilic granular cytoplasm and central oval nuclei
Case 2
The importance of EUS also lies in its ability to detect small lesions, which could
be missed on MDCT. A 40-year-old male presenting with abdominal pain showed an intensely
enhancing solitary lesion in the pancreatic neck on the pancreatic parenchymal phase,
a diagnosis of pancreatic neuroendocrine tumors (NET) was given. EUS was, however,
able to discover few other hypoechoic lesions of size <1 cm in the pancreas. The patient
was operated for pancreatic NETs [Figure 3].
Figure 3 (A-E): Pancreatic parenchymal phase axial (A) and coronal (B) CT images showing a solitary
avidly enhancing lesion in pancreatic neck (arrow) with dilated MPD and atrophic parenchyma.
Diagnosis of NET was made. Endoscopic US shows multiple hypoechoic SOLs in pancreatic
neck (C), body (D) and tail (E), few of them sub-centimetric in size. EUS guided FNA
showed them to be multiple NETs, confirmed on histology after enucleation
Case 3
The MDCT of a 43-year-old female demonstrated a hypodense mass in the head of the
pancreas, with the involvement of superior mesenteric vein (SMV), the fat plane between
the lesion and superior mesenteric artery (SMA) was preserved. The mass was found
to be resectable pancreatic adenocarcinoma on MDCT. EUS, however, differed in regard
to SMA involvement by the mass lesion. EUS reported the mass to be unresectable owing
to the SMA involvement. Peroperative findings showed that the SMA was not involved
by the mass and the tumor was resectable [Figure 4].
Figure 4 (A-F): Axial CT pancreatic parenchymal (A), image show a hypodense mass lesion (star) in
pancreatic head. Axial (B-D) and sagittal (E) arterial MIP images show the fat plane
between mass (star) and SMA ( arrow) is preserved, rendering the mass resectable.
The EUS (F) showing the mass (star) involving the SMA (arrow), suggesting the mass
to be unresectable. Histologically mass was proven to be pancreatic adenocarcinoma
Case 4
A heterogeneously enhancing mass lesion was seen on MDCT of a 40-year female. The
SMA appeared normal at its origin and in its proximal course but was encased and attenuated
in its mid-course. On EUS it was difficult to demonstrate such involvement of SMA
due to the inability to angulate the transducer along the entire course of SMA [Figure 5].
Figure 5 (A-F): Axial CT pancreatic parenchymal phase image (A) shows an avidly enhancing mass (star)
with areas of central necrosis. CT diagnosis of NET was made. Axial (B) and sagittal
(C) arterial MIP images show complete encasement of superior mesenteric artery (arrow)
in its distal course by the mass. The VRT image (D) of the arterial tree shows the
reduced caliber of the superior mesenteric artery (arrow) in its distal course with
normal caliber at its origin and proximal course. EUS images (E and F) show a hypoechoic
mass (star) in head of pancreas with SMA appearing normal at origin
These cases emphasized the importance of MDCT the in assessment of vascular structures
to determine the operability of the mass
Case 5
A well-defined lobulated cystic lesion was seen on MDCT abdomen of a 60-year-old female
who presented with pain in abdomen since 1 year. No obvious internal septations/enhancing
mural nodule was seen on CT images. Possibilities of oligocystic variant of serous
cystadenoma and mucinous cystadenoma were considered on CT. Endoscopic ultrasound
following CT showed a well-defined cystic lesion in the pancreatic head in relation
to the main portal vein. EUS-guided needle aspiration of the cyst revealed multiple
microcysts, characteristic of serous cystadenoma around the primary cystic lesion
with the aspiration of serous fluid from the cyst. EUS and EUS-guide cyst aspiration
can contribute significantly in determining the internal features of a cyst and allow
for fluid analysis aspirated from a cyst to reach the final diagnosis [Figure 6].
Figure 6 (A-E): Axial CT pancreatic parenchymal (A), and coronal venous phase (B) images show a lobulated
cystic lesion (arrow) in pancreatic head. EUS shows a cystic lesion (arrow) in head
of pancreas, in relation to the portal vein (PV) (C). EUS guided cyst aspiration (D)
shows partial collapse of cyst with microcysts (open arrow) and internal septations
(arrow) in the large cyst. Serous fluid aspirated from the cyst (E). Diagnosis of
oligocystic serous cystadenoma was given
The best outcomes were obtained with combined use of MDCT and EUS imaging with addition
of EUS guided interventions (EUS-FNA or EUS guided cyst aspiration). Thus, we support
the fact that the most optimal use of these modalities is as complimentary rather
than as competing tools in preoperative work up of pancreatic lesions.
We accept that there are several limitations to our study. It was a single center
prospective study, endoscopic ultrasound being an invasive modality was done only
for cases with significant/equivocal findings on MDCT after obtaining proper consent
& pre-anesthesia clearance of participating subjects. All these factors resulted in
a small sample with a heterogenous mixture of pathologies. Owing to the limited sample
size, sensitivity, specificity, PPV and NPV of MDCT and EUS could not be compared
and calculated for characterization of lesions. Also, endoscopic ultrasound as a preoperative
imaging modality for pancreatic tumors has been recently established at our center,
therefore the percentage correct diagnosis, sensitivity and specificity is lower compared
to literature value.
Conclusion
MDCT and Endoscopic US are important pre-operative imaging tools for evaluation of
any pancreatic mass. MDCT is superior to EUS for characterization of pancreatic masses,
assessing local and distant spread of disease owing to its larger coverage area and
to look for vessel involvement by a mass lesion as well as to define vascular anatomy.
EUS is superior to CT in cases where CT findings were equivocal/indefinite, lesions
were <1 cm in size as a result of better resolution due to close proximity of ultrasound
transducer to the pancreas and for lesions requiring concurrent tissue sampling/ fluid
aspiration. Combined use of MDCT, EUS imaging, EUS guided interventions provided best
results in our study and therefore a combination of these modalities should be used
to reach the final diagnosis.
