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Augmented reality for laparoscopic liver surgery 59
Figure 4.14 The guided acquisition of ultrasound images within a 3D volume allows vessels to be reconstructed and aligned to the
preoperative CT surface models efficiently during surgery, improving registration accuracy in cases of organ deformation and
movement. Source: Sugimoto et al. [12]. Reproduced with permission of Wiley.
detection of deeper structures ensures a more accurate
alignment throughout the entire volume and allows
the surgeon to repeat the alignment multiple times during
the operation, thus adjusting for the deformation encountered during dissection. Such technology will be applied to
laparoscopic liver surgery in the future, most likely utilizing electromagnetictracking systems for positiondetection
of the flexible ultrasound probe.
4.5.2 Visualization
Another fundamental challenge in the development and use
of AR systems relates to data visualization. While AR eliminates the need for sight diversion, the display of additional
information can potentially be misleading or disturbing
during surgical procedures. Furthermore, depth encoding
and visualization of deeper structures in a way that results in
natural and coherent integration with the laparoscopic view
has still not been addressed. Several different solutions have
been proposed, such as the use of transparency and color
depth coding or distance patterns [16], but few have found a
place in a clinical scenario. Merging 3D surface models with a
2D laparoscopic image or projection of a 2D image onto the
real-world 3D patient anatomy makes the achievement of
realistic and understandable guidance challenging. For
example, superimposition of a vascular structure onto the
laparoscopic image gives the perception of the structure
floating in front of the image. The laparoscopic instrument
is then visualized behind the superimposed structure in the
laparoscopic image. Display of a virtual instrument allows
the relationship of instrument with tissue to be visualized.
However, the display of a 3D virtual instrument onto a
real laparoscopic instrument can prove distracting (see
Figure 4.8). For tasks in which contact between instrument
and tissues is required, 2D guidance information such as that
shown in Figure 4.12 may be more useful. Additionally,
researchers are investigating the use of combined visual and
audiofeedbacktoovercomedeficiencies experienced in
purely visually augmented reality. For example, image overlay AR can be used to guide the surgeon’s tool to the region of
a structure, and sound can be used to indicate the distance
from the tool to the structure as a structure of interest
is approached.
4.6 The future of augmented reality
for laparoscopic liver surgery
Despite the possible benefits of AR technologies for laparoscopic HPB procedures, quantitative clinical evaluations of their effectiveness are yet to be performed. To
60 Chapter 4
date, validation of AR systems for surgery has consisted
primarily of feasibility studies conducted with a small
number of clinical cases. Results are typically reported
as subjective evaluations with little or no significant
quantitative data. Evaluation of AR technologies in widespread and larger clinical trials would prove the advantages and disadvantages of the technology and aid in the
development of existing systems. The general approach of
AR for laparoscopic surgery has been successfully validated. Identifying applications for which AR can be most
effective and developing dedicated systems for solving
specific surgical challenges are the obvious next steps
towards a successful integration of AR technologies
into clinical routine.
Superimposed anatomical structures provide additional general information to the surgeon. Task-specific
guidance, provided by image guidance systems in other
surgical domains, such as needle guidance, resection
margin calculations, distance or functional measurements, etc., has not been significantly explored for laparoscopic surgery. Therefore, AR applications that solve
KEY POINTS
problems specific to laparoscopic surgeons must be developed. The development of features that aid in accomplishing specific tasks of laparoscopic HPB surgery may
lead AR to transform from being something that is “nice to
have” into an indispensable tool similar to image-guided
systems in other surgical domains. The use of AR systems
in laparoscopic surgeries as described in this chapter,
although useful in some aspects of clinical practice,
requires a significant amount of further research before
the full potential of AR visualization can aid surgeons and
ultimately patients.
From a technical perspective, AR technologies that
provide optimal integration into the clinical workflow
and a reliable level of accuracy are currently being investigated by a number of research groups. Devices and
algorithms for automatic laparoscope calibration and
methods of registration that more effectively address
organ movement are currently being researched, and
dedicated systems for AR guidance in laparoscopic liver
surgery incorporating such functionalities are likely to
become commercially available in the near future.
• Augmented reality is the supplementation of a real-world view with aligned real-time computer-generated information.
• Augmentation data can be created from preoperative or intraoperative images and can be superimposed onto laparoscopic
images or projected directly onto the patient during HPB laparoscopic procedures.
• Augmented reality visualization for HPB laparoscopic surgery has the potential to improve spatial understanding and the
localization of hidden underlying structures.
• Employing a position measurement system for instrument tracking allows augmented reality scenes to be updated in real time as
the laparoscopic view changes.
• Challenges pertaining to the registration of deformable anatomy and to the display of depth information within augmentation
data remain the primary focus for current research in laparoscopic augmented reality guidance solutions.
References
1 Cleary K, Peters TM. Image-guided interventions: technology
review and clinical applications. Annu Rev Biomed Eng 2010;
12:119–142.
2 Peterhans M, Oliveira T, Banz V, Candinas D, Weber S.
Computer-assisted liver surgery: clinical applications and
technological trends. Crit Rev Biomed 2012:40:199–220.
3 Marescaux J, Rubino F, Arenas M, Mutter D, Soler L. Aug-
mented-reality-assisted laparoscopic adrenalectomy. JAMA
2004; 292:2214–2215.
4 Peters TM. Image-guidance for surgical procedures. Phys Med
Biol 2006; 51:R505–540.
5 Konishi K, Hashizume M, Nakamoto M, et al.Augmented reality
navigation system for endoscopic surgery based on threedimensional ultrasound and computed tomography: application
to 20 clinical cases. Int Congr Ser 2005; 1281:537–542.
6 Fusaglia M, Gavaghan K, Beldi G, et al. Endoscopic image
overlay for the targeting of hidden anatomy in laparoscopic
visceral surgery. In: Augmented Environments for Computer-Assisted Interventions. Berlin: Springer, 2013.
7 Gavaghan K, Anderegg S, Peterhans M, Oliveira-Santos T,
Weber S. Augmented reality image overlay projection for
image guided open liver ablation of metastatic liver cancer. In:
Augmented Environments for Computer-Assisted Interventions. Berlin: Springer, 2011, pp. 36–46.
Augmented reality for laparoscopic liver surgery 61
8 Gavaghan K, Peterhans M, Oliveira-Santos T, Weber S. A
portable image overlay projection device for computer-aided
open liver surgery. IEEE Trans Biomed 2011; 58:1855–1864.
9 Fuchs H, State A, Yang H, et al. Optimizing a head-tracked
stereo display system to guide hepatic tumor ablation. Stud
Health Technol Inform 2008; 132:126–131.
10 Soler L, Nicolau S, Schmid J, et al. Virtual reality and aug-
mented reality in digestive surgery. Presented at the Third
IEEE and ACM International Symposium on Mixed and
Augmented Reality, 2004, pp. 278–279.
11 Buchs N, Volonté F, Pugin F, et al. Augmented environments
for the targeting of hepatic lesions during image-guided
robotic liver surgery. J Surg Res 2013; 184(2):825–831.
12 Sugimoto M, Yasuda H, Koda K, et al. Image overlay naviga-
tion by markerless surface registration in gastrointestinal,
hepatobiliary and pancreatic surgery. J Hepatobiliary Pancreat Sci 2010; 17:629–636.
Videos 1–20 will be of interest to readers of this chapter.
Visit the companion website at:
13 Volonté, F, Pugin F, Bucher P, Sugimoto M, Ratib O, Morel
P. Augmented reality and image overlay navigation with
OsiriX in laparoscopic and robotic surgery: not only a
matter of fashion. J Hepatobiliary Pancreat Sci 2011; 18:
506–509.
14 Schenk A, Zidowitz S, Bourquain H, et al. Clinical relevance of
model based computer-assisted diagnosis and therapy. Proceedings of SPIE 6915, Medical Imaging 2008: ComputerAided Diagnosis, 691502. doi: 10.1117/12.780270.
15 Peterhans M, Weber S. A navigation system for open liver
surgery: design, workflow and first clinical applications. Int J
Med Robotics Comput Assist Surg 2011; 7:7–16.
16 Hansen C, Wieferich J, Ritter F, Rieder C, Peitgen H. Illustra-
tive visualization of 3D planning models for augmented reality
in liver surgery. Int J Comput Assist Radiol Surg 2010; 2:
133–141.
www.wiley.com\go\conrad\liver-pancreas-biliary-laparoscopic-surgery
CHAPTER 5
Imaging of hepatopancreatobiliary diseases
Motoyo Yano,1Hillary Shaw,2and Kathryn J. Fowler
1
Department of Radiology, Washington University School of Medicine, St Louis, USA
2
Radia Inc., PS, Lynwood, USA
EDITOR COMMENT
In this important and practically written chapter, the authors detail important imaging modalities for HPB surgeons. The authors
summarize the available imaging modalities and their complementary nature for the assessment of critical HPB lesions. Communication
with the radiology team is crucial to determine the optimal imaging modality for each patient. This is especially true for minimally invasive
HPB surgeons because of their greater reliance on imaging owing to reduced haptic feedback and the challenges of fully screening
the liver with intraoperative ultrasound. MRI has the advantage of not using nephrotoxic contrast agents. Nevertheless, limitations for the
use in patients with impaired renal function exist. Additional advantages of MRI are the ability to provide crucial information about lesion
characteristics and underlying liver disease. Ultrasound is not only essential for intraoperative surgical planning; it is also an important
screening modality for hepatocellular carcinoma in patients with chronic liver disease.
Keywords: computed tomography, focal liver les ions, imaging for hepatopancreatobiliary disease, imaging of liver di sease,
magnetic resonance imaging, nuclear imaging, ultra sound
1
5.1 Overview of available imaging 5.1.1 Ultrasound and Doppler
modalities
There are various imaging modalities available for the
evaluation of hepatopancreatobiliary (HPB) diseases, and
each imaging modality has its strengths and weaknesses.
Imaging modalities include ultrasound and Doppler,
computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine examinations. The best
choice of imaging examination depends upon the clinical
question, and examinations are often complementary.
For example, if detailed anatomical information regarding the extent of vascular involvement by a pancreatic
adenocarcinoma is desired, a CT or MRI would be the
most appropriate imaging modality. On the other hand,
the question of acute cholecystitis is best addressed with a
right upper quadrant ultrasound. When the best choice of
imaging is uncertain, consultation with the radiologist
can help to develop a diagnostic plan (Table 5.1).
Ultrasound images are produced by the interaction of
acoustic waves with tissues of varying densities. Acoustic
waves propagate through tissues from the transducer
applied to the patient, and the echoes that return to the
transducer are processed into gray-scale images. Grayscale images demonstrate structures in varying degrees
of brightness, or echogenicity, based upon the degree to
which the penetrated tissues attenuate the sound wave.
Ultrasound can provide real-time anatomical information
about the liver,bile ducts, and gallbladder. However, while
ultrasound is ideal for assessing the liver, the pancreas can
be difficult to evaluate because of the interposition of gascontaining bowel between the pancreas and abdominal
wall; gas within the bowel impedes the transmission of
acousticwaves. An advantageof ultrasound is theability to
assess vessels without the use of intravenous contrast.
Doppler ultrasound generates color-scale images for evaluation of patency, flow direction, and flow velocity in
Laparoscopic Liver, Pancreas, and Biliary Surgery: Textbook and Illustrated Video Atlas, First Edition.
Edited by Claudius Conrad and Brice Gayet.
© 2017 John Wiley & Sons, Ltd. Published 2017 by John Wiley & Sons, Ltd.
62
Imaging of hepatopancreatobiliary diseases 63
Table 5.1
Strengths and weaknesses of ultrasound, CT, and MRI.
Imaging modality Strengths Weaknesses
Ultrasound Economical Operator dependent
Readily available Limited spatial resolution and tissue characterization
Doppler can assess vessel patency without Limitations due to obese body habitus
need for intravenous contrast
No radiation
Computed tomography Widely available Ionizing radiation
Fast Contrast media can be nephrotoxic
Excellent spatial resolution
Multiphasic postcontrast imaging
Magnetic resonance imaging Excellent soft tissue contrast and Motion sensitive
characterization Not suitable for some patients (uncooperative, limited breathMultiphasic postcontrast imaging holding, some implanted devices, claustrophobia)
No radiation Variable protocols and image quality between imaging centers
Contrast media not nephrotoxic
vessels.Additional strengths of ultrasound include the lack
of ionizing radiation, portability, low cost, and widespread
availability [1].
There are some limitations to ultrasound. Image quality
and detection of pathology are operator dependent
(Figure 5.1). An ultrasound examination is a real-time
interactive test during which the patient is asked to hold
their breath and change position so that structures of
interest can be optimally visualized. Ultrasound image
quality may be limited by patient body habitus. Adipose
tissue attenuates acoustic waves, limiting their ability to
penetrate through the subcutaneous tissues of obese
patients [2]. In the evaluation of the liver, hepatic steatosis also impedes the propagation of sound waves and
makes detection of liver lesions more difficult [3]. Focal
lesion detection in cirrhotic livers can also be more challenging as cirrhosis increases the echogenicity (brightness) and coarsens the echotexture of the liver [4].
Ultrasound in the intraoperative setting is crucial in the
detection and localization of disease. It provides real-time
high-resolution imaging which does not suffer from limitations of conventional sonography, such as large body
habitus, since the transducer is placed directly on the
organ/structure of interest [5]. For example, in the liver,
lesions which were indeterminate preoperatively by CT
or MRI can be further characterized by their sonographic
features, with intraoperative ultrasound-guided biopsy
for histological diagnosis. Intraoperative ultrasound not
Figure 5.1 A 52-year-old man with ascites and cirrhosis
secondary to hepatitis C. Annual screening ultrasound
demonstrated increased echogenicity, coarsened echotexture,
and surface nodularity consistent with cirrhosis. No lesions
were initially identified by the sonographer. On further
scanning by the radiologist, a hyperechoic liver lesion with a
hypoechoic rim suspicious for hepatocellular carcinoma was
identified in the dome of the liver on this transverse ultrasound
image. This lesion demonstrated growth and features of
hepatocellular carcinoma on follow-up MR examination
(not shown).
64 Chapter 5
infrequently identifies other unsuspected lesions in the
liver [6]. Intraoperative ultrasound is similarly used in
the identification of multifocal neuroendocrine tumors in
the pancreas [7].
5.1.2 Computed tomography
Computed tomography examinations are commonplace
and the modality is familiar to most physicians. Transaxial
CT images are produced by attenuation of X-ray beams
that rotate around the patient as the CT table advances the
patient through the gantry in a single breath hold (newgeneration scanners can acquire head-to-toe images in a
matter of seconds). CT involves the use of ionizing radiation and frequently requires the use of iodinated intravenous contrast material to increase the sensitivity of the
examination [8]. CT contrast agents can be nephrotoxic
and generally should not be administered to patients in
acute renal failure as there is an increased risk for contrast-induced nephrotoxicity [9]. In the setting of chronic
renal failure, CT contrast can be administered and dialyzed. Patient reactions to CT contrast are commonly
encountered and may necessitate either avoidance of
contrast or premedication, depending on the severity of
the reaction [10].
There are various CT imaging protocols which can be
tailored to best answer a specific clinical question [11,12].
Variation in CT imaging technique is mostly related to phase
of contrast for image acquisition, voltage, and section thickness [13]. Thin sections allow for improved multiplanar
reconstructions of images acquired in the axial plane with
minimal loss of resolution or blurring of the reconstructed
image [14]. A routine contrast-enhanced abdomen CT is
typically performed in the portal venous phase of contrast.
For the purposes of assessing most HPB diseases, noncontrast CT is generally low yield, except to evaluate calcifi-
cations, to assess acute bleeding, or to evaluate enhancement
in the setting of high attenuation material (such as hemorrhage or chemoembolization material). However, the precontrast phase is important and can help to identify areas of
contrast enhancement amidst the high attenuation embolization material.
Evaluation of focal liver lesions should be performed
with intravenous contrast using a dedicated liver protocol
which consists of images acquired in the arterial, portal
venous, and delayed phases [15]. The reason for these
multiple phases of contrast in the liver relates to identification of classic enhancement patterns for distinguishing
between lesions [16]. In the pancreas, lesion conspicuity
is greatest in the late arterial phase (Figure 5.2). Additionally, thin section images are helpful for increased
spatial resolution in pancreatic imaging to allow for
detailed assessment of resectability [17,18]. The evaluation of the biliary tree is performed with both multiphase
CT and thin section images [19]. Oral contrast is generally
not necessary in the assessment of hepatopancreatobiliary disease; however, if there is concern for a duodenal
mass or ampullary pathology, water administered by
mouth while the patient is on the CT table can be helpful
in distending the duodenum and improving visualization [20] (Table 5.2).
Figure 5.2 A 63-year-old man with incidentally discovered pancreatic lesion. Noncontrast (a), arterial (b), and venous (c) phases of
the examination demonstrate arterially enhancing lesion in the pancreatic tail consistent with neuroendocrine tumor. Note the
greater lesion conspicuity on the arterial phase images relative to the background normal pancreatic parenchyma.
Imaging of hepatopancreatobiliary diseases 65
Table 5.2
5.1.3 Magnetic resonance imaging
Magnetic resonanc e imaging utilizes magnetic fields
and radiofrequency pulses to generate images that
provide excellent soft tissue contrast [22]. MRI protocols are often customized to answer a specific clinical
question. MR i mages can be obtained in any plane.
While MRI entails no exposure to radiation, th ere is
the possibility of tissue heating because of deposited
energy. There are some patie nt populations , such as
pregnant patients, in whom attempts are made to minimize sequences which in turn minimizes tissue heating
(referredtoasspecifi c absorption rate – SAR) that
occurs with MRI [23]. As with CT, postcontrast MR
images are multiphasic, typically ima ging during the
late arterial, portal venous, equilibrium, and delayed
phases. Some protocols which utilize contrast taken up
by hepatocytes (hepatobiliary agents) c all for delayed
images, typically at one hour for gadobenate dimeglumine (Multihance) and 20–40 minutes for gadoxetic
acid (Eovist).
characterization of liver and pancreatic lesions. Gadolinium (in contrast to CT contrast media) is not nephrotoxic at clinically utilized doses and therefore will
not have negative effects on glomerular filtration rate
(GFR). While not nephrotoxic, gadolinium contrast
Phases of contrast used in typical CT protocols [11,15,21].
Region of interest Non-con Early art Late art Portal venous Delayed
Abdomen
Liver Focal lesion characterization
Post-TACE
Bile ducts
Pancreas
Arteries ±
TACE: transarterial chemoembolization; typically performed for hepatocellular carcinoma.
Non-con: noncontrast, prior to the infusion of intravenous contrast.
Early art: early arterial phase of contrast, approximately 25 sec after initiating contrast infusion. Bolus tracking is typically used with ROI placed in the
descending aorta. This phase of contrast is helpful for arterial angiography (CT angiography).
Late art: late arterial phase which is approximately 35–45 sec after initiating contrast infusion. Usually results in enhancement of arteries and early
opacification of the portal vein. This phase is adequate in assessing pertinent arterial vasculature.
Venous: this phase occurs approximately 60–80 sec after the start of contrast infusion.
Delayed: this phase refers to any phase of imaging beyond the venous phase, and the duration of delay is variable depending on the organ/structure
of interest.
p p p
p p p
p
p p p
p p
p
agents have been linked to nephrogenic systemic
fibrosis (NSF). NSF is a chronic, potentially fatal, systemic fi brosing disease highly associated with renal
impairment and administration of gadolinium contrast [24]. The FDA has issued a black box warning
against use of gadolinium contrast in the setting of
severe renal disease. As a result, most imaging centers
have enforced screening policies and GFR cut-off values which vary by institution. Pregnant patients are
also generally imaged without gadolinium contrast, as
gadolinium crosses the placenta and m ay remain
indefinitely in the amniotic fluid, with unknown
effects to the fetus [23].
Disadvanta ges of MRI include long exam times,
approximately 30 minutes for an MRI of the abdomen,
as well as the degradation of image quality by patient
motion, both gross motion and ina bility to hold the
breath. Some conditions such as severe ascites or large
pleural effusions should be addressed prior to imaging to
help improve the patient’s ability to comply with breath-
Gadolinium intravenous contrast is required for full
holding instructions.
Some patients may have contraindications to MR
examination, such as presence of metallic shrapnel in
the orbits or implantation of a non-MRI-compatible pacemaker/defibrillator. With the ever expanding list of new
devices implanted in patients, dynamic online resources
66 Chapter 5
such as MRIsafety.com are valuable in determining the
MR compatibility of devices [25].
5.1.4 Nuclear medicine
Nuclear medicine imaging differs from cross-sectional
modalities in that these examinations provide metabolic
and functional information, often fused with anatomical
cross-sectional imaging. In nuclear scintigraphy examinations, the physiological uptake of intravenously administered radiopharmaceuticalsis detected and imaged using a
gamma camera. Many of these examinations require
continuous patient imaging for greater than one hour
and some examinations require patients to return for
imaging at four hours and 24 hours, and even 48 hours
after injection of radiopharmaceutical [26] (Table 5.3).
Cholescintigraphy is most often used in establishing the
diagnosis of acute cholecystitis. While gallbladder sonography evaluates for secondary signs of gallbladder inflammation, hepatic iminodiacetic acid (HIDA) scans can
determine functional obstruction of the cystic duct. The
HIDA radiopharmaceutical is injected intravenously and
is extracted by hepatocytes and excreted through the
biliary system. In the setting of acute cholecystitis, there
is obstruction of the cystic duct and the radiotracer fails to
fill the gallbladder (Figure 5.3). Patients are required to be
NPO for 3–4 hours prior to the exam, as a contracting
gallbladder will prevent accumulation of tracer in the
gallbladder. In patients who have been NPO for greater
than 24 hours, a cholecystokinin (CCK) analogue is
administered to contract and empty a full gallbladder,
which can prevent accumulation of radiotracer in
the gallbladder. HIDA scans can also be performed for
the evaluation of chronic acalculous cholecystitis in
which gallbladder ejection fraction is compromised.
Excretion of this agent can also be utilized to evaluate
bile leak in the postoperative setting [27].
Some of the anatomical limitations of nuclear scintigraphy can be overcome with the simultaneous acquisition
of CT images which allow for improved anatomical localization [26], such as the case with fluorodeoxyglucose
(FDG) positron emission tomography (PET)/CT exami-
18
nations.
F-FDG uptake occurs in metabolically active
tissues, greater than background activity in many neoplasms and inflammatory conditions. Increased FDG
uptake is seen with some hepatocellular carcinomas,
cholangiocarcinomas, pancreatic adenocarcinomas, and
many metastases to the liver. Some tumors, such as lowgrade neuroendocrine tumors and mucinous adenocarcinomas from the gastrointestinal tract, are generally not
FDG avid and cannot be detected with PET/CT [28].
Tumors that are less than 1 cm may also escape detection
by PET/CT (Figure 5.4). False-positive results may be
encountered secondary to local inflammatory reaction
in the postoperative and postablation settings [28].
Heat-damaged red blood cell (RBC) scans will demonstrate uptake in splenic tissue. This exam is useful when
accessory spleens and splenosis cause a diagnostic
dilemma on CT and MRI. Depending on their location,
these soft tissuedeposits can be difficult to distinguish from
neoplasticprocesses. A classic exampleis the identification
Table 5.3 Overview of common nuclear scintigraphy exams in HPB disease.
Nuclear scintigraphy exam Common indications Limitations
Cholescintigraphy (HIDA scan) Acute cholecystitis
Chronic acalculous cholecystitis
Bile leak
PET/CT
Somatostatin receptor
scintigraphy (octreoscan)
Heat-damaged RBC Identification of splenules, splenosis
HIDA, hepatic iminodiacetic acid; HPB, hepatopancreatobiliary; FDG, fluorodeoxyglucose (
tomography; RBC, red blood cell.
Detection of FDG-avid, hypermetabolic tumors and
their distant metastases
Neuroendocrine tumors (NETs) and their metastases
False positives for acute cholecystitis with poor
patient preparation
Not all tumors are FDG avid
FDG uptake by small lesions may not be detected
Sensitivity of lesion detection may be limited in the
postchemotherapy setting
Not all NETs express the somatostatin receptor
subtype 2 detected by octreoscan
18
F); PET/CT, positron emission tomography/computed
Imaging of hepatopancreatobiliary diseases 67
Figure 5.3 A 66-year-old woman with nausea, vomiting, and leukocytosis. Patient underwent noncontrast CT examination (a) in
the emergency room, followed by right upper quadrant ultrasound, which both demonstrated gallbladder distention (b,c) and mild
wall thickening (d). Sonographic Murphy’s sign was negative. As a result of equivocal findings on ultrasound, patient underwent
HIDA scan which failed to demonstrate radiotracer uptake within the gallbladder after one hour (e) and after administration of
morphine (f). Failure to identify radiotracer uptake in the gallbladder is consistent with acute cholecystitis, in this case treated with
cholecystostomy tube, as the patient was not a surgical candidate. For reference, a normal HIDA scan is shown, demonstrating tracer
uptake in the gallbladder (g).
68 Chapter 5
Figure 5.3 (Continued)
of a soft tissue nodule in the pancreatic tail prompting a
differential diagnosis of a pancreatic neoplasm such as
neuroendocrine tumor or an intrapancreatic splenule
(Figure 5.5) [29]. Heat-damaged RBC scans are more
sensitive and specific for splenic tissue than sulfur colloid
scans, and they are the exam of choice [30,31] in this
clinical scenario.
111
Somatostatin receptor scintigraphy utilizes
In-DTPA
octreotide to detect tumors expressing somatostatin
receptors. In HPB diseases, octreoscans are used in the
detection of gastroenteropancreatic neuroendocrine
tumors. Octreoscans detect tumors which express
somatostatin receptor subtype 2, but not all neuroendocrine tumors express this subtype and therefore
may fail to be detected [32,33]. Gallium 68-labeled
somatostatin analogues for PET imaging, although less
widely available, demonstrate greater lesion detection
ability than somatostatin receptor scintigraphy [32].
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