AJR 2005; 184:852-854
© American Roentgen Ray Society
3D Pancreatic Arteriography with MDCT During Intraarterial Infusion of Contrast Material in the Detection and Localization of Insulinomas
Koji Takeshita1,
Kimiko Kutomi1,
Koichi Takada1,
Hiroshi Kohtake1 and
Shigeru Furui1
1 All authors: Department of Radiology, Teikyo University School of Medicine,
2—11-1, Itabashi-Ku, Tokyo 173—8605, Japan.
Received April 27, 2004;
accepted after revision July 23, 2004.
Address correspondence to K. Takeshita
(takesita{at}med.teikyo-u.ac.jp).
Introduction
Multiphasic contrast enhancement CT with IV contrast administration has
been used for the diagnosis of insulinomas
[1–3].
Although recent reports of studies using MDCT have suggested improved
performance in revealing these tumors, MDCT may fail to depict some lesions
[1]. Because insulinomas are
generally found as small nodules with a hypervascular nature, MDCT with
intraarterial contrast infusion (MDCT-IA) may show the tumors more clearly by
increasing the attenuation difference between the lesions and pancreatic
parenchyma. Three-dimensional images obtained by this method may offer
additional information for more accurate diagnosis or localization of the
lesions. We describe the results of MDCT-IA in three patients with
histologically proven insulinomas compared with those of MDCT with IV contrast
material infusion (MDCT-IV) and digital subtraction angiography.
Materials and Methods
Three patients with insulinomas underwent the three examinations in this
order: MDCT-IV, digital angiography, and MDCT-IA. Informed consent was
obtained from the three patients. One patient with an insulinoma in the
pancreatic head underwent enucleation of the tumor (patient 1). The other two
patients—one with three insulinomas in the pancreatic tail (patient 2)
and one with one insulinoma in the pancreatic body (patient 3)—underwent
partial pancreatectomy. Diagnosis and the number of the lesions were confirmed
histopathologically.
In the MDCT-IV examination, the amount of contrast material administered
was determined by multiplying the weight of the patient (in kilograms) by 2 mL
of contrast medium. This dose was administered at 300 mg I/mL IV during 30
sec. A three-phase contrast study was performed using 2.5-mm collimation
through the pancreas as a breath-held acquisition. Arterial phase imaging was
performed 25 sec after the initiation of IV contrast administration.
Pancreatic phase imaging was performed 50 sec and portal venous phase imaging
was performed 75 sec after the initiation of IV contrast administration.
Digital subtraction angiography of the superior mesenteric and celiac
arteries was then performed in all three patients.
For MDCT-IA, arterial access was obtained with bilateral femoral artery
punctures using the Seldinger technique. Two catheters were placed, one in the
superior mesenteric artery and one in the celiac artery. The examination was
performed on an 8-MDCT unit (LightSpeed QX/I, GE Healthcare). Initially, an
unenhanced image of the upper abdomen was obtained using 7-mm collimation to
determine the location of the pancreas. For MDCT-IA, 60 mL of nonionic
contrast material (150 mg I/mL) was used: the two catheters were joined with a
Y-shaped connector, and the contrast material was injected through the
Y-shaped connector at a rate of 6 mL/sec with a power injector. MDCT
was performed using 1.25-mm collimation with a pitch of 10.5 through the
entire pancreas with a breath-holding acquisition. Scanning delay time was 3
sec after the initiation of intraarterial contrast administration. The images
were reconstructed at 0.63-mm intervals, using a 20-cm field of view. These
data were then transferred to a workstation (Advantage Windows 3.1, GE
Healthcare). MDCT-IA images were reconstructed with a volume-rendering
technique using multiprojection volume reconstruction software by selecting a
slab containing the peripancreatic arteries.
Detection and localization of the lesions were evaluated, and the MDCT-IA
findings were compared with those of digital subtraction angiography and
MDCT-IV. Maximum attenuation differences between the lesion and the pancreatic
parenchyma on the axial images obtained with MDCT-IA and with MDCT-IV in the
three-phase enhanced study were compared in the three patients.
Results and Discussion
In patient 1, MDCT-IA and 3D images obtained by MDCT-IA clearly showed a
hypervascular nodule in the pancreatic head
(Fig. 1). Both MDCT-IV and
digital subtraction angiography also showed the lesion. Maximum attenuation
differences between the lesion and the pancreatic parenchyma on the data
obtained by MDCT-IA and MDCT-IV were 127 H and 64 H, respectively.
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Fig. 1. —55-year-old woman with insulinoma of pancreas. 3D image obtained
using MDCT-IA with volume-rendering technique on anteroposterior view shows
tumor in pancreatic head fed by pancreaticoduodenal arcades.
|
|
In patient 2, MDCT-IA and 3D images obtained by MDCT-IA clearly showed
three contiguous tumors in the pancreatic tail (Figs.
2A,
2B,
2C, and
2D). MDCT-IV also showed all of
the lesions, although their appearance was less conspicuous. Digital
subtraction angiography showed the three tumors as an indiscrete tumor stain;
therefore, the precise number of the lesions was undeterminable. Maximum
attenuation differences among the three lesions compared with the pancreatic
parenchyma on the data obtained by MDCT-IA and MDCT-IV were 418 H and 86 H for
the anterior lesion, 512 H and 88 H for the middle lesion, and 420 H and 84 H
for the posterior lesion, respectively.
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Fig. 2A. —55-year-old woman with insulinomas of pancreas. Axial images
obtained using MDCT-IA (A) and MDCT-IV during pancreatic phase
(B) and 3D image obtained using MDCT-IA with volume-rendering technique
on caudocranial view (C) show three contiguous tumors in pancreatic
tail. Tumors were more conspicuous on image of MDCT-IA than that of MDCT-IV.
Peripancreatic arteries, including feeding arteries originating from splenic
artery, are also seen on 3D image (C). Digital subtraction angiography
image (D) shows tumor stain at pancreatic tail, but number of lesions
could not be determined.
|
|
View larger version (115K):
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[as a PowerPoint slide]
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Fig. 2B. —55-year-old woman with insulinomas of pancreas. Axial images
obtained using MDCT-IA (A) and MDCT-IV during pancreatic phase
(B) and 3D image obtained using MDCT-IA with volume-rendering technique
on caudocranial view (C) show three contiguous tumors in pancreatic
tail. Tumors were more conspicuous on image of MDCT-IA than that of MDCT-IV.
Peripancreatic arteries, including feeding arteries originating from splenic
artery, are also seen on 3D image (C). Digital subtraction angiography
image (D) shows tumor stain at pancreatic tail, but number of lesions
could not be determined.
|
|
View larger version (70K):
[in this window]
[in a new window]
[as a PowerPoint slide]
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Fig. 2C. —55-year-old woman with insulinomas of pancreas. Axial images
obtained using MDCT-IA (A) and MDCT-IV during pancreatic phase
(B) and 3D image obtained using MDCT-IA with volume-rendering technique
on caudocranial view (C) show three contiguous tumors in pancreatic
tail. Tumors were more conspicuous on image of MDCT-IA than that of MDCT-IV.
Peripancreatic arteries, including feeding arteries originating from splenic
artery, are also seen on 3D image (C). Digital subtraction angiography
image (D) shows tumor stain at pancreatic tail, but number of lesions
could not be determined.
|
|
View larger version (150K):
[in this window]
[in a new window]
[as a PowerPoint slide]
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Fig. 2D. —55-year-old woman with insulinomas of pancreas. Axial images
obtained using MDCT-IA (A) and MDCT-IV during pancreatic phase
(B) and 3D image obtained using MDCT-IA with volume-rendering technique
on caudocranial view (C) show three contiguous tumors in pancreatic
tail. Tumors were more conspicuous on image of MDCT-IA than that of MDCT-IV.
Peripancreatic arteries, including feeding arteries originating from splenic
artery, are also seen on 3D image (C). Digital subtraction angiography
image (D) shows tumor stain at pancreatic tail, but number of lesions
could not be determined.
|
|
In patient 3, MDCT-IA and 3D images obtained by MDCT-IA clearly showed a
hypervascular nodule in the pancreatic body. Both MDCT-IV and digital
subtraction angiography also showed the lesion. Maximum attenuation
differences between the lesion and the pancreatic parenchyma on the data
obtained by MDCT-IA and MDCT-IV were 123 H and 66 H, respectively.
Recently, MDCT has been introduced with 3D technique providing high-quality
CT angiography derived from rapid scanning and high spatial resolution for the
evaluation of pancreatic tumors
[4–6].
To our knowledge, 3D CT arteriography during intraarterial infusion of
contrast material for the detection and localization of insulinomas has not
been reported previously. MDCT-IA is a combination of MDCT and catheter
angiographic techniques and can provide data with both sufficient arterial
enhancement during the optimal temporal window and high spatial resolution for
thin collimation derived from MDCT. Our data suggest that the tumor
conspicuity is increased by intraarterial contrast administration more than by
IV contrast administration with higher maximum attenuation differences between
the lesion and the pancreatic parenchyma.
Although digital subtraction angiography can depict the lesion as
hypervascular or nodular-staining, peripancreatic vessels or the spleen may
hide the lesions, and if the lesions are multiple, one lesion may hide other
lesions on the anteroposterior view. In patient 2, three insulinomas in the
pancreatic tail were close to each other and were superimposed against the
spleen; therefore, the shape and number of the lesions were not well defined
on digital subtraction angiography.
The 3D images obtained by MDCT-IA clearly showed the 3D structure of the
tumors, peripancreatic vasculature, and feeding arteries on the same display.
If tumors lie adjacent to enhancing vessels or are pedunculated, they
potentially can be missed on axial imaging. The 3D images provide a multiangle
display of an oblique slab containing the specific vessel of interest, and
this technique may improve the tumor detection in problematic cases.
Preoperative localization for insulinoma by multiple diagnostic techniques
has been controversial. Surgery performed under the guidance of intraoperative
ultrasound and preceded by only one preoperative imaging technique has been
reported to be the best approach for establishing the diagnosis and treatment
of insulinomas [7]. However,
accurate localization and determination of the number of tumors may provide
valuable information regarding the type of surgery required. If tumors are
located deep in the pancreas, partial pancreatectomy may be required, whereas
tumors located near the surface of the pancreas can be treated by enucleation.
Accurate preoperative localization is also valuable in minimizing operative
palpation and excluding nesidioblastosis as a cause of hypoglycemia
[1].
Selective intraarterial calcium stimulation with hepatic venous sampling is
reported to be an accurate and safe method for preoperative localization of
insulinomas [8]. Our results do
not obviate hepatic venous sampling because it can be useful to detect
hypovascular or small lesions.
In our results with three patients, all five insulinomas depicted on
MDCT-IA were also seen on MDCT-IV. However, the appearance of the tumors was
more conspicuous on MDCT-IA with the higher maximum attenuation differences
between the lesions to pancreatic parenchyma. These results suggest a
potential application of MDCT-IA for the detection of hormonally active islet
tumors, which are radiographically occult or produce equivocal findings on
digital subtraction angiography or MDCT-IV. MDCT-IA may also be useful for
evaluating multiplicity of islet cell tumors in cases in which one or more
lesions have been found on other diagnostic studies.
In conclusion, MDCT-IA seems to be useful for the depiction of insulinomas.
Further studies are necessary to determine the application of this new
method.
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Introduction
Materials and Methods
