Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3860_Библиотеки_им_академика_М_И_Перельмана
.pdf
https://t.me/med1917
J.D. Georgia and D. L. MillerArteriography and Venous Sampling
https://t.me/med1917
34
■■■
Arteriography and Venous Sampling
of the Parathyroid Glands,
Pancreas, and Adrenal Glands
JEFFREY D. GEORGIA AND DONALD L. MILLER
All endocrine localization procedures, including arteriography and venous sampling, are used in patients with
clinically evident syndromes of hormone excess. There
are two indications for localization procedures: localization of otherwise occult tumors and differentiation between single and multiple gland involvement. Clinical
syndromes and the invasive localization procedures that
may be indicated in their workup are listed in Table 34-1.
These procedures may be required for tumor localization
in patients with any of these disorders. Differentiation of
single and multiple gland involvement is a common
problem in patients with Conn syndrome (hyperaldosteronism) and a rare problem in patients with virilizing
tumors.
None of the endocrine diseases listed in Table 34-1 are
common, and most are rare. It follows that the localization procedures listed in Table 34-1 also are rarely used.
Except in large academic medical centers, most of these
procedures are unlikely to be performed on a sufficiently
regular basis that a resident or fellow in interventional
radiology will become familiar with them. Nonetheless, it
is useful to know when, why, and how they are performed,
as well as how they are interpreted. This chapter describes the catheter-based localization procedures used
for endocrine disorders of the parathyroid glands, the
pancreas, and the adrenal glands. Nowadays, localization
procedures are virtually never required for patients with
pheochromocytoma and are needed so rarely in patients
with virilizing tumors that they are not discussed here,
but they are reviewed elsewhere.
Arteriography and venous sampling are not used as
first-line techniques in patients with endocrine disorders
because of their greater risk and expense compared with
1
noninvasive radiologic techniques. The specific order in
which radiologic procedures are used varies for each organ and disease. Appropriate protocols are briefly described below in sections devoted to specific organs.
■ General Principles of Endocrine
Localization
Endocrine localization procedures differ from most other
radiologic studies in that their purpose is not to establish
a diagnosis but rather to identify an adenoma, carcinoma,
or hyperplastic gland whose existence has already been
established by endocrine testing but whose location is
unknown. The diagnosis of a disorder of hormone excess
never requires demonstration of a tumor or enlarged
gland. The most basic principle of endocrine localization
efforts is “diagnosis first, localization second.” These studies are certain to yield misleading results if the diagnosis is
wrong.
Equally important is an understanding of the advantages and limitations of venous sampling procedures.
These are physiologic studies, not imaging procedures.
They do not require visualization of an abnormality to
provide localization. This is both the great strength and
the major weakness of this technique.
On the one hand, because it is not necessary to visualize a tumor, the sensitivity of venous sampling is independent of tumor size. It is equally good for the detection
of 1-mm and 3-cm lesions. The only requirements are
that the lesion secretes sufficient hormone to be detected
and that the appropriate vein is sampled. Nonfunctioning adenomas and similar red herrings do not cause
425
426 J. D. Georgia and D. L. Miller
https://t.me/med1917
TABLE 34-1. Clinical Endocrine Syndromes and
Localization Procedures
Organ Localization procedure
Pituitary
Cushing syndrome/disease Petrosal sinus sampling
Ectopic ACTH syndrome
Parathyroid
Hyperparathyroidism Parathyroid arteriography
Parathyroid venous sampling
Pancreas
Zollinger-Ellison syndrome Pancreatic arteriography
Insulinoma Arterial stimulation and venous
sampling
Adrenal
Conn syndrome Adrenal venous sampling
Ovary
Virilizing tumors Adrenal and ovarian venous
sampling
ACTH, adrenocorticotropic hormone.
false-positive results with venous sampling, as they may
with imaging studies.
The disadvantage of the procedure is that, because the
tumor is never seen during a venous sampling procedure,
it cannot be localized precisely. Instead, venous sampling
permits regionalization; that is, it defines a territory
drained by a specific vein or veins in which the abnormality must lie. In addition, because tumor presence is presumed based on the evidence of hormone production,
the test is only accurate if all production of the hormone
by normal glandular tissue is suppressed. When venous
sampling procedures are performed on patients without
endocrine disease, false-positive studies are virtually certain. For this reason, as already stated, a diagnosis of
endocrine hyperfunction must be established before localization procedures are begun.
■ Hyperparathyroidism
Clinical review
In normal subjects, elevated serum calcium inhibits production of parathyroid hormone (PTH) through a negative feedback loop. Primary hyperparathyroidism is defined as
excess production of PTH resulting from a loss of the
normal feedback inhibition fromelevated serum calcium.
Increased hormone levels may result from parathyroid
hyperplasia (multiple gland involvement), parathyroid
adenoma (involvement of a single gland), or, rarely, parathyroid carcinoma. The elevated serum calcium concentration is caused by increased renal retention, bone
resorption, and increased absorption from the gut. Patients may develop osteolysis leading to bone pain and
pathologic fractures, urinary stone disease, and neuromuscular physiologic dysfunction. Symptoms may be sub-
tle, vague, and nonspecific. Increasingly, the diagnosis of
abnormal parathyroid function is made through the widespread use of routine laboratory screening panels, which
include calcium assays coupled with improved techniques
for measurement of PTH.
2,3
Localization
Most experienced endocrine surgeons believe that noninvasive imaging studies are not required in patients who
present with primar y hyperparathyroidism, because the
initial neck exploration is curative in more than 90% of
these patients.
necessary in these patients,
4–7
No preoperative localization studies are
8–12
although some surgeons
advocate their use in combination with unilateral neck
exploration.
13–17
There is general agreement that patients with persistent or recurrent hypercalcemia following surgery will benefit from radiologic localization prior
to reoperation, because each additional surgical exploration is more difficult, carries a alreadyhigher risk of vocal
cord paralysis, and is less likely to succeed.
9
An effective localization protocol for these patients has
been devised.
9
Noninvasive studies should be performed
first, because they are less expensive and less risky. The
imaging studies with the greatest sensitivity at present are
sestamibi scintigraphy, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound. These
modalities are all operator dependent in terms of performance, interpretation, or both; their sensitivity and
false-positive rates vary widely and overlap. Sestamibi scintigraphy is probably the single best noninvasive test.
18
We
believe an abnormal parathyroid gland should be demonstrated by at least two of these modalities before localization is considered complete in order to avoid false-positive
localizations. The order in which the various studies are
performed should be based on individual institutional experience. All imaging protocols should account for the
possibility of ectopic mediastinal or suprathyroid parathyroid glands, although most parathyroid glands identified
at reoperation are in the neck.
At most institutions, if noninvasive studies are negative
or equivocal, parathyroid arteriography is performed
9,19
next.
Parathyroid arteriography will demonstrate an
abnormal parathyroid gland in approximately 60% of patients in whom noninvasive studies are negative or equivocal. Parathyroid venous sampling, the final localization
procedure in the workup of these patients, will permit
localization to one side of the neck or to the mediastinum
in 80 to 90% of the remaining few patients in whom all
other studies have failed to image an abnormal gland.
Anatomy
Most people have four parathyroid glands, although as
few as three and as many as eight have been reported.
20
In the normal anatomic position, the glands adhere to
https://t.me/med1917
the posterior surface of the thyroid gland (Fig. 34-1).
They also may be ectopic and may be located anywhere
from the angle of the jaw to the mediastinum (Fig. 34-2).
Knowledge of the common locations of normal and
ectopic glands in a prerequisite to successful localization
by inter ventional techniques. Fortunately, most ectopic
glands lie along specific, well-defined pathways of embryologic descent, either in the anterior mediastinum and
thymus or in the tracheoesophageal groove and superior
mediastinum.
20,21
Each parathyroid gland usually is supplied by a single
22,23
artery.
The arterial supply to parathyroid glands located in the normal anatomic position is provided by the
paired superior thyroid arteries from the external carotid
artery and the paired inferior thyroid arteries from the
thyrocervical trunk (Fig. 34-1). Anterior mediastinal and
thymic glands are supplied by branches of the internal
mammary artery (Fig. 34-3). Superior mediastinal and
tracheo-esophageal groove glands usually are supplied by
a branch of the inferior thyroid artery. The venous anatomy of the thyroid bed is quite variable. Detailed descriptions of the venous anatomy relevant to parathyroid venous sampling have been published
24–26
and should be
reviewed by the angiographer prior to attempting this
study.
Venous drainage from the parathyroid glands commonly occurs through ipsilateral superior, middle, and
inferior thyroid veins (Figs. 34-4 and 34-5). The superior
thyroid vein drains through the facial vein into the internal jugular vein, and the middle thyroid vein drains directly into the internal jugular vein. Both inferior thyroid
veins commonly drain into the left brachiocephalic vein,
either separately or by a combined trunk. Less commonly,
the rightinferior thyroid vein drainsdirectly into the right
brachiocephalic vein (see Fig. 34-4). The left thymic vein
empties into the left innominate vein; elevations of PTH
in the thymic vein suggest that the abnormal parathyroid
gland is located in the anterior mediastinum. The anatomy and anastomotic connections of this vein are quite
variable, and mediastinal parathyroid glands often drain
into the inferior thyroid veins (Fig. 34-6).
27
Analysis of the
venous drainage patterns observed at arteriography is essential to permit correct interpretation of the results of
venous sampling.
Arteriography
Digitally subtracted, superselective, six-vessel studies (bilateral thyrocervical trunks, internal mammary arteries,
and common carotid arteries) deliver the highest yield.
Venous-phase images are also obtained to provide “roadmaps” and to define venous drainage patterns in cases
where venous sampling proves necessary (see Fig. 34-5). If
the common carotid artery injections are not clearly nega-
Arteriography and Venous Sampling 427
FIGURE 34-1. Arterial supply to the thyroid and parathyroid
glands. The parathyroid glands are adherent to the posterior
surface of the thyroid gland. The superior and inferior thyroid
arteries ramify along the posterior aspect of the thyroid gland,
but are shown here on the anterior surface for the purpose of
clarity. The drawing displays the typical supply from the inferior
and superior thyroid arteries. When ectopic parathyroid glands
are located in the thymus of elsewhere in the anterior mediastinum, they are usually supplied by a branch of the internal
mammary artery (see Fig. 34-3). 1, aorta; 2, brachiocephalic
trunk; 3, left common carotid; 4, left subclavian; 5, subclavian;
6, right common carotid; 7, thyrocervical trunk; 8, inferior thyroid; 9, suprascapular; 10, tranverse cervical; 11, vertebral; 12,
28
internal thoracic; 13, ascending cervical; 14, external carotid;
15, internal carotid; 16, superior thyroid; 17, superior laryngeal;
18, lingual; 19, facial.
428 J. D. Georgia and D. L. Miller
https://t.me/med1917
FIGURE 34-2. Location of ectopic parathyroid glandsbased on
a series of 104 glands identified at reoperation. The numbers
are percentages. Note the frequency of tracheoesophageal and
thymic glands. These represent, respectively, ectopic superior
and inferior glands. Tracheoesophageal groove glands typically
are supplied by the inferior thyroid artery, whereas thymic
glands are supplied by the internal mammary artery. (Modified
from Wang C-A. Parathyroid re-exploration: a clinical and
pathological study of 112 cases.
with permission.)
Ann Surg
1977;186:140–145,
tive, bilateral superior thyroid artery injections may be
helpful to clarify the arteriographic findings. If all else
fails, an arch aortogram may reveal a thyroidea ima artery
(present in approximately 6% of persons),
29
which most
commonly arises from the aortic arch, the innominate
artery, or the right common carotid artery and supplies
variable portions of the thyroid and parathyroid
glands.
29,30
This regimen demonstrates an abnormal
parathyroid glandin approximately 60% of the patients in
whom noninvasive imaging is negative or inconclu-
19,31
sive.
Parathyroid arteriography has a low false-positive
rate.
The aortic arch, common carotid arteries, and, if necessary, the superior thyroid arteries may be catheterized by
using standard techniques and catheters; however, these
are the least useful vessels for parathyroid localization.
Catheterization of the thyrocervical trunk, a critical vessel
FIGURE 34-3. Parathyroid adenoma supplied by the left internal mammary artery. A single vessel from the thymic branch
(
long arrow
smooth-margined area of intense, homogeneous blush (
arrow
DL. Endocrine angiography and venous sampling.
North Am
) of the internal mammary artery supplies an oval,
wide
), which is typical of a parathyroid adenoma. (From Miller
Radiol Clin
1993;31:1051–1067, with permission.)
in parathyroid arteriography, is often more difficult. It
may be helpful to steam a Berenstein-type catheter so that
the curvature of the bend is more gradual and the angle is
tighter. The internal mammary artery,which arises anteriorly or anteroinferiorly from the subclavian artery, and
not directly inferiorly, should be catheterized first. After
internal mammary arteriography is performed, the catheter is withdrawn slowly until it is near the orifice of the
internal mammary artery. As gentle puffs of contrast material are injected, the catheter is withdrawn further and
rotated anteriorly to engage the orifice of the thyrocervical trunk. The thyrocervical trunk arises from theanterior
or antero-superior aspect of the subclavian artery, but it or
Arteriography and Venous Sampling 429
https://t.me/med1917
FIGURE 34-4. Anatomy of veins draining the thyroid bed and portions of the anterior mediastinum. The inferior thyroid veins, in particular, are subject to considerable variation, and both
often drain into the left brachiocephalic vein, frequently as a combined trunk. The vertebral veins
and thymic veins are not shown, for clarity. The vertebral veins empty in the brachiocephalic veins
slightly posteromedial to the internal jugular veins and commonly have valves near their bases.
The left thymic vein drains into the anteroinferior aspect of the left brachiocephalic vein in the
midline. The right thymic vein drains directly into the inferior vena cava and cannot normally be
catheterized. 1, superior vena cava; 2, right brachiocephalic; 3, left brachiocephalic; 4, subclavian;
5, inferior thyroid; 6, internal jugular; 7, middle thyroid; 8, superior thyroid.
430 J. D. Georgia and D. L. Miller
https://t.me/med1917
A B
FIGURE 34-5. Thyrocervical arteriograms demonstrate arterial and venous anatomy in a patient with recurrent hyperparathy-
roidism following surgery. No abnormal parathyroid gland was identified on this study. A: A left thyrocervical trunk injection
demonstrates the ascending cervical artery (
the typical looping course of the inferior thyroid artery (
supply portions of the esophagus and trachea. Note the excellent demonstration of the venous drainage of the left thyroid lobe
into the left inferior thyroid vein (
demonstrates venous drainage of the right thyroid lobe into the right superior thyroid vein (
vein (
open arrows
), and the right vertebral vein (
curved arrow
one or more of its branches may share a common origin
with the internal mammary artery.
The thyrocervical trunk can be recognized by the characteristic looping course of the inferior thyroid artery (see
Figs. 34-1 and 34-5) Although the inferior thyroid artery
occasionally may have been ligated at the initial surgery,
failure to identify this vessel usually means that the cathe-
long arrow
). B: Selective injection into the right inferior thyroid artery in the same patient
), the transverse cervical and suprascapular arteries (
short arrows
short arrows
). The inferiorly directed branches of the inferior thyroid artery
long arrow
). Both arteriograms also demonstrate the normal thyroid blush.
open arrows
), the right inferior thyroid
hancement, often superimposed on thyroid tissue (see
Fig. 34-3). With optimal radiographic technique and collimation, pathologic glands as small as 4 to 5 mm may be
visible. Normal parathyroid glands are never visualized
angiographically in these patients because their PTH production is suppressed and the glands become quite small
(1–2 mm).
32
), and
ter is in the costocervical trunk, not the thyrocervical
trunk. The costocervical trunk arises from the posterosuperior aspect of the subclavian artery, adjacent to the thyrocervical trunk, and usually is much easier to catheterize
than the thyrocervical trunk. Intentional injection of the
costocervical trunk shouldbe avoided,however, because it
often supplies a major feeder to the cervical spinal cord.
At arteriography, hyperplastic and adenomatous parathyroid glands are oval or rounded areas of diffuse en-
Venous sampling
Venous sampling relies on the unilateral PTH gradients
produced by hyperfunctioning parathyroid glands. Mapping the PTH concentrations in selective samples from
draining veins reveals the source of elevated hormone
production because the remaining normal glands are
suppressed and their draining veins contain only back-
FIGURE 34-6. Thymic vein venogram. The catheter tip is in
https://t.me/med1917
the left thymic vein (
heads
) are clearly visible. In this patient, anastomoses are
present between the thymic vein and both inferior thyroid veins
(
long arrows
venous sampling.
with permission.)
open arrow
). (From Miller DL. Endocrine angiography and
Radiol Clin North Am
). Thymic vein branches (
1993;31:1051–1067,
arrow-
ground levels of PTH. Concentrations of PTH more than
twice as high as the background level are generally considered diagnostic, but gradients are commonly much
higher in selective samples from small veins.
33
In 80 to
90% of patients in whom angiography fails to delineate
the source of abnormality, parathyroid venous sampling
will be positive.
34
In a series of 86 patients with negative
or equivocal noninvasive localization studies and arteriograms, parathyroid venous sampling had a sensitivity
of 88% and a specificity of 86%.
34
Because hyperplasia is often asymmetric, bilateral but
usually unequal elevations in PTH above background are
the most common finding in patients with primary hyperplasia. Venous sampling usually is not performed in patients with hyperplasia unless only a single gland remains
occult or four glands have been identified and resected
at surgery but the patient remains hypercalcemic.
Arteriography and Venous Sampling 431
The delayed venous-phase images from the parathyroid
arteriogram are invaluable bothfor clarifyingvenous anatomy and for guiding interpretation of the results of venous
sampling, because the venous drainage patterns of the
thyroid bed are different in the postoperative neck than in
the normal neck. Venous sampling usually is not performed without a preceding arteriographic study. Falsepositive rates for parathyroid venous sampling of 6 to 18%
without arteriography drop to 0 to 4% when a preceding
arteriogram is done.
9,34
Patients who have undergone surgical exploration will
invariably have undergone ligation of the middle thyroid
veins (failure to do so is a mark of an inadequate exploration), and often the inferior thyroid veins have been
ligated as well. Venous drainage from the thyroid bed is
usually by the vertebral veins, which should always be
sampled. Superior and inferior thyroid veins should be
sampled bilaterally, if possible. Samples from the thymic
vein may be essential to localize a thymic gland. Internal
jugular vein samples are occasionally helpful. Less selective venous sampling (innominate vein, subclavian vein)
generally does not produce a sufficient gradient above
background to localize the abnormality. Left innominate
vein samples may be particularly treacherous because this
vein receives drainage from both sides of the neck as well
as from the mediastinum.
33,35
Because it is often necessary to use a number of differently shaped catheters to sample all these veins, a sheath
should be placed in the femoral vein at the beginning of
the procedure. The vertebral, internal jugular, and inferior thyroid veins all may be catheterized using a Berenstein or similarly shaped catheter. Difficulty advancing
the guidewire past the valve at the base of the left internal
jugular vein is common. Hyperextension of the neck,
combined with repeatedly advancing and withdrawing of
the guidewire while the patient is taking deep breaths, is
usually successful.
36
Catheterization of the superior thyroid and thymic
veins is often more difficult. The original literature described the use of a tip-deflecting catheter-guidewire assembly, which is no longer manufactured. No really satisfactory substitute is available. If the brachiocephalic and
internal jugular veins are large enough, a shepherd’s
hook, visceral hook, Mikaelsson, or inferior mesenteric
catheter may be successful. It is often necessar y to steam
a catheter to an appropriate shape or to modify an existing catheter. Use of a tip-deflecting wire may help in
catheterization of the superior thyroid veins and thymic
vein. It is helpful to remember that the thymic vein originates from the anteroinferior aspect of the left brachiocephalic vein. The thymic vein is usually the most difficult
vein to catheterize during parathyroid venous sampling,
but it is also one of the most important, and so extensive
efforts at catheterization are justified.
It is essential to obtain a sample from the femoral vein
432
https://t.me/med1917
J. D. Georgia and D. L. Miller
sheath at the conclusion of the procedure. This serves as
the peripheral vein sample against which all of the other,
selective samples will be compared.
After each sample is obtained, and before the catheter
is moved, a small amount of contrast material should be
injected gently and a spot film (either conventional or
digital) obtained to document the position of the catheter tip and the site from which the sample was obtained.
As each sample is obtained, the sample number and the
location from which it was obtained should be recorded.
At the conclusion of the procedure, this list should be
included as part of the dictated report, a copy of the list
attached to the patient’s chart, and an additional copy
included in the film jacket with the spot films. It takes
several days to a week or more to get the PTH levels back
from the laboratory, by which time recollection of the
details of the sampling procedure may be hazy. Without
the information from the spot films and the sample list,
the PTH data may be meaningless.
Venous sampling is time consuming and requires careful attention to proper labeling and handling (including
interim storage) of the samples; an elegant diagnostic
procedure and hours of effort may come to naught by a
call from the laboratory stating that the melting ice bath
has caused 20 labels to be cast adrift from their parent
tubes. All such preparations, including documentation of
the site from which each sample was obtained, preparation of specimen tubes, and details of specimen handling
and transport, should be made and reviewed in advance
with the angiography suite technical staff and the hospital chemistry laboratory, particularly given the complexity and relative infrequency of the study. Delegation of
sample management to an intern is not wise.
■ Pancreatic Endocrine Tumors
Clinical review
Islet cell tumors of the pancreas may produce any of a
number of gastroenteropancreatic hormones. Some islet
cell tumors are referred to as “clinically silent” because
they overproduce hormones, such as pancreatic polypeptide, that do not result in clinical symptoms.
with clinically silent islet cell tumors present with symptoms that result from mass effect rather than endocrine
disorders; their tumors are usually larger than 5 cm and
are easily identified by CT or ultrasound. Islet cell tumors
that secrete excesses of other hormones, principally insulin, gastrin, and glucagon, result in well-defined endocrine syndromes. These islet cell tumors are referred to as
functioning tumors, and tend to produce clinical symptoms
while stillquite small (often ⬍ 1 cm). The two functioning
islet cell tumors that most commonly present difficulties
in localization are insulinomas and gastrinomas.
37
Patients
Differences between insulinoma
and gastrinoma
Whipple’s triad (symptoms of hypoglycemia, demonstrated low blood glucose level, and relief of symptoms
with glucose administration) is the clinical prerequisite of
insulinoma. Symptoms are often due to the effects of
hypoglycemia on the brain, and many patients are initially misdiagnosed as having a neurologic or psychiatric
disorder. Hypoglycemia in the presence of elevated insulin levels is strong evidence of an insulinoma. (An alternative etiology is surreptitious self-administration of
insulin.)
Insulinomas, the most common islet cell tumor, tend to
be solitary (92%), intrapancreatic (99.5%), and benign
(90%).
37
They are distributed uniformly throughout the
pancreas, with 75% located to the left of the superior
mesenteric artery. Accurate localization of these tumors is
important because no adequate medical therapy exists
and surgical resection is the definitive treatment.
38
Gastrinoma, the second most common functioning islet cell tumor, produces elevated serum gastrin levels,
which leads to hypersecretion of gastric acid and multiple
peptic ulcers. These two findings, in addition to the presence of a non-beta cell islet cell tumor, constitute the
Zollinger-Ellison syndrome; diarrhea is also a common
feature. Unlike insulinomas, 60% of gastrinomas are malignant, 60% are multiple, and more than 30% are extrapancreatic.
37
About 75 to 90% of gastrinomas are located
to the right of the superior mesenteric artery, in the
pancreas, duodenum, or in the peripancreatic lymph
nodes. Gastrinomas are small; duodenal tumors are typically smaller than 1 cm.
Multiple tumors are the rule in the 25% of patients
with the Zollinger-Ellison syndrome who have multiple
endocrine neoplasia syndrome type 1 (MEN-1), which
syndrome includes tumors or hyperplasia of the pancreas, parathyroid, and pituitary. The characteristically
multiple and malignant nature of gastrinomas makes
their localization often more challenging than that of
insulinomas. Additionally, treatment of gastrinoma is less
straightforward than insulinomas because of the much
higher incidence of metastatic lesions, most commonly
within the liver.
38
Localization
As with all suspected endocrine neoplasms, attempts at
localization should begin only after the diagnosis has
been confirmed. Preoperative imaging is undertaken initially to determine whether metastases are present. If the
patient is a surgical candidate, imaging is used to locate
the primary tumor. How aggressively preoperative localization should be pursued in patients with insulinoma is
controversial, because these tumors usually are easily
Arteriography and Venous Sampling 433
https://t.me/med1917
identified with the combination of intraoperative ultrasound and palpation.
37,39–45
The four noninvasive modalities currently used to localize primary islet cell tumors and to detect liver metastases are ultrasound, CT, MRI, and somatostatin receptor
scintigraphy. The first three are cross-sectional imaging
studies, whereas the last is a functional study based on a
physiologic property of the tumor (the presence of somatostatin receptors). Noninvasive cross-sectional studies
are used primarily to evaluate for metastatic disease, but
they also may reveal the primar y tumor simultaneously.
If noninvasive methods have not identified a primary
tumor, the patient should next undergo either arteriography with arterial stimulation and venous sampling
(ASVS) or endoscopic ultrasound, depending on the
availability of suitable equipment and experienced opera-
37,39–43,46,47
tors.
Some authors continue to recommend
portal venous sampling as a final option, but we believe
this technique has been superseded by ASVS.
37,39
Portal
venous sampling is far more difficult technically and has
a higher complication rate.
48
Anatomy
The arterial anatomy of the pancreas and duodenum is
described in Chapters 28 and 32. The arteries of principal
concern are the celiac axis, the superior mesenteric ar-
tery, and their branches. There is considerable variability
in branching patterns in the celiac and superior mesenteric arteries. The body and tail of the pancreas receive
numerous branches from the splenic artery. The pancreatic head is supplied by the gastroduodenal artery. The
dorsal pancreatic artery, via the transverse pancreatic artery, may supply the entire pancreas.
Pancreatic/hepatic arteriography
Arteriography has largely been replaced by newer, less
invasive modalities as the initial technique for tumor detection, but it remains valuable for localization of insulinomas and in conjunction with ASVS.
lesion that can be visualized by arteriography is approximately 5 mm compared with at least 7 mm for CT and
conventional ultrasound and 5 to 6 mm for endoscopic
ultrasound.
49,50
Pancreatic endocrine tumors and their
metastases appear as foci of homogeneous staining during
the capillary phase (Fig. 34-7).
1,37
defined, round or oval lesion with smooth margins. Neither neovascularity nor arteriovenous shunting is demonstrable in small lesions, but tumors larger than 2 cm may
demonstrate abnormal vessels and prominent draining
37
veins.
Arteriography is capable of demonstrating hyper-
vascular hepatic metastases smaller than 5 mm in diame-
51
ter.
Rare islet cell tumors may be hypovascular.
1,37,42
The smallest
They are usually sharply
52,53
FIGURE 34-7. Arteriogram of an insulinoma. The tumor (
smooth margin and an intense, homogeneous blush. It is supplied by branches of the superior
mesenteric artery. It is rather large for a benign insulinoma. The patient was cured following surgical
resection.
arrows
) is round and well defined, with a
Соседние файлы в папке Библиотека им академика М.И. Перельмана