DOI:10.2214/AJR.06.0794
AJR 2007; 188:992-999
© American Roentgen Ray Society
Splenic Artery Aneurysms and Pseudoaneurysms: Clinical Distinctions and CT Appearances
Gautam A. Agrawal1,
Pamela T. Johnson and
Elliot K. Fishman
1 All authors: Department of Radiology, Johns Hopkins School of Medicine, 601 N
Caroline St., Rm. 3251, Baltimore, MD 21287.
Received June 16, 2006;
accepted after revision September 12, 2006.
Address corresondence to P. T. Johnson
(pjohnso5{at}jhmi.edu).
CME This article is available for CME credit. See
www.arrs.org
for more information.
FOR YOUR INFORMATION
This article is available for CME credit. See
www.arrs.org
for more information.
Abstract
OBJECTIVE. Aneurysms of the splenic artery are being diagnosed with
greater frequency as incidental findings on cross-sectional imaging. Splenic
artery pseudoaneurysms are even more rare than true aneurysms. This article
reviews the clinical features and management of splenic artery aneurysms and
pseudoaneurysms. A variety of cases are presented to show the range of CT
appearances.
CONCLUSION. Radiologists who identify either type of splenic artery
lesion should recognize the clinical and pathophysiologic distinctions between
these two forms of splenic vascular pathology and understand the differences
in management.
Keywords: abdomen • angiography, CT • pancreatitis • spleen
Introduction
The splenic artery is the third most common site of intraabdominal
aneurysms after aneurysms of the abdominal aorta and the iliac arteries
[1]. The true prevalence is
unknown, with estimates varying widely, from 0.2% to as high as 10.4%
[2,
3]. Although they were once
thought to be rare, with wider use of cross-sectional imaging, splenic artery
aneurysms are being diagnosed with increasing frequency as incidental findings
[4]. As uncommon as true
splenic artery aneurysms are, pseudoaneurysms are even more rare, with fewer
than 200 cases reported in the English-language literature
[5]. Radiologists who identify
these vascular pathologies must recognize the clinical significance and
understand the management. This article reviews the clinical features, CT
appearance, and management of splenic artery aneurysms and
pseudoaneurysms.
Incidence
Beaussier [6] reported the
first case of splenic artery aneurysm in 1770 at necropsy. These relatively
uncommon lesions are being incidentally detected with greater frequency as a
result of the widespread use of high-resolution imaging techniques. The true
prevalence data are widely varying, from 0.098% in a large autopsy series to
0.78% in a study of 3,600 arteriograms to 10.4% in an autopsy series on
patients 60 years or older with special attention given to the splenic artery
[2,
3,
7]. Splenic artery aneurysm is
four times more common in women but approximately three times more likely to
rupture in men [8].
In contrast to splenic artery aneurysm, splenic artery pseudoaneurysm
(Fig. 1) is rare. In a large
series from the Mayo Clinic, 10 splenic artery pseudoaneurysms were compiled
over 18 years [5]. To date,
fewer than 200 cases have been reported in the English-language
literature.
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Fig. 1 —Schematic of normal splenic artery, splenic artery aneurysm, and
pseudoaneurysm. In true aneurysm, wall is composed of intima (I), media (M),
and adventitia (A); in comparison, pseudoaneurysm wall contains only intima
and media. In setting of pancreatitis, splenic artery pseudoaneurysm may
result from weakening of wall by pancreatic enzymes
[5]. (Illustration by Frank
Corl)
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Pathophysiology
Although the precise etiology of splenic artery aneurysm remains unknown,
it has been associated with hypertension, portal hypertension, cirrhosis,
liver transplantation, and pregnancy
[8-10].
Less commonly associated conditions include arterial fibrodysplasia,
arteritis, collagen vascular disease, 
1-antitrypsin
deficiency, and inflammatory and infectious disorders
[8]. In contrast to aneurysms
of larger vessels such as the aorta, atherosclerosis is not considered to be
the underlying cause. Histopathologically, 80-99% of splenic artery aneurysms
reveal atherosclerosis; however, this is probably a secondary process
occurring from primary degeneration of the media
[1,
4,
11].
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Fig. 2 —44-year-old woman undergoing evaluation as potential renal donor
with no significant medical history. Arterial phase contrast-enhanced CT scan
shows 2-cm distal splenic artery aneurysm located near splenic hilum, which
was confirmed with arteriography.
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Fig. 3 —78-year-old man with history of treated bladder cancer who presented
with persistent hematuria. Arterial phase contrast-enhanced CT scan reveals
2-cm aneurysm arising from mid portion of splenic artery.
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Fig. 4A —63-year-old woman with splenic artery aneurysm detected 2 years
previously who is being evaluated for stability. Axial arterial phase contrast
enhanced CT scan (A) and sagittal oblique multiplanar reformation
(B) show 1.8-cm aneurysm with dense peripheral calcification. Aneurysm
appeared unchanged since prior examination.
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Fig. 4B —63-year-old woman with splenic artery aneurysm detected 2 years
previously who is being evaluated for stability. Axial arterial phase contrast
enhanced CT scan (A) and sagittal oblique multiplanar reformation
(B) show 1.8-cm aneurysm with dense peripheral calcification. Aneurysm
appeared unchanged since prior examination.
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True aneurysms of the splenic artery are usually smaller than 3 cm, ranging
from 2 to 9 cm in one series of nine cases
[11]. They may be multiple and
are most commonly located in the distal portion of the artery
(Fig. 2), although they can
arise from other segments of the splenic artery
(Fig. 3). Peripheral
calcification (Fig. 4A,
4B) is common; Dave et al.
[11] reported that 80% show
atherosclerotic changes including calcification, and mural thrombus may be
present (Fig. 5).
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Fig. 5 —50-year-old woman with history of Gaucher's disease and incidentally
discovered splenic artery aneurysm on CT. Axial arterial phase
contrast-enhanced CT scan shows 2.2-cm, partially thrombosed, peripherally
calcified aneurysm (arrow) arising from distal splenic artery.
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The causes of splenic artery pseudoaneurysm include pancreatitis (Fig.
6A,
6B), trauma, iatrogenic and
postoperative causes, and, rarely, peptic ulcer disease
[5]. In the case of
pancreatitis, pancreatic enzymes are thought to cause a necrotizing arteritis
with destruction of vessel wall architecture and fragmentation of elastic
tissues, leading to aneurysm or pseudoaneurysm
[12]. In addition to direct
damage of vascular structures by the spread of pancreatic enzymes from severe
inflammation, Flati et al.
[13] described another
mechanism by which pancreatitis related pseudoaneurysms can form. A
longstanding pseudocyst may induce a pseudoaneurysm, caused by vascular
erosion from enzymes within the pseudocyst, direct compression, or ischemia
[13].
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Fig. 6A —48-year-old man with chronic pancreatitis and 2- to 3-day history of
abdominal pain. Axial late arterial phase contrast-enhanced CT scan (A)
and volume-rendered image (B) show 3 x 2.5 cm partially
thrombosed pseudoaneurysm (arrow) adjacent to tail of pancreas,
probably secondary to previous pancreatitis. Pseudoaneurysm was treated by
interventional coil embolization.
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Fig. 6B —48-year-old man with chronic pancreatitis and 2- to 3-day history of
abdominal pain. Axial late arterial phase contrast-enhanced CT scan (A)
and volume-rendered image (B) show 3 x 2.5 cm partially
thrombosed pseudoaneurysm (arrow) adjacent to tail of pancreas,
probably secondary to previous pancreatitis. Pseudoaneurysm was treated by
interventional coil embolization.
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A combination retrospective case series and literature review reported that
the mean size of splenic artery pseudoaneuryms was 4.8 cm (range, 0.3-17 cm)
[5]. Those authors noted that a
coexisting pseudocyst was present in 41% of cases. Secondary hemor-rhage from
pseudoaneurysms may involve the pancreatic duct, peritoneum, retroperitoneum,
adjacent organs (stomach, colon), or a pseudocyst if one is present
[5,
13].
Clinical Presentation
Clinically, most splenic artery aneurysms are asymptomatic. A large series
from the Mayo Clinic showed that 97.5% of patients with nonruptured splenic
artery aneurysms were asymptomatic
[8]. Early reports of splenic
artery aneurysm suggested the risk of rupture is 10%
[14]. However, more recent
data suggest rupture rates closer to 2-3%
[15,
16]. The frequency of rupture
is increased with liver transplantation, portal hypertension, and pregnancy
[17]. Typical clinical
presentations of ruptured splenic artery aneurysm include abdominal pain (Fig.
7A,
7B,
7C), hemodynamic instability,
and gastrointestinal bleeding. The sudden onset of left upper quadrant pain
usually indicates rupture has occurred
[17]. There can be spontaneous
stabilization and subsequent sudden circulatory collapse. This is termed the
"double rupture" phenomenon, whereby initial bleeding tamponades
into the lesser sac, followed by flooding into the peritoneal cavity
[18].
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Fig. 7A —45-year-old man who presented with syncope due to spontaneous,
intraperitoneal hemorrhage while exercising, source of which was not
identified during surgical exploration or by postoperative CT angiography at
outside institution. Axial early venous phase image (A) and sagittal
multiplanar reformation (B) from IV contrast-enhanced MDCT reveal
2.5-cm aneurysm posterior to pancreas and adjacent residual retroperitoneal
and intraperitoneal hemorrhage.
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Fig. 7B —45-year-old man who presented with syncope due to spontaneous,
intraperitoneal hemorrhage while exercising, source of which was not
identified during surgical exploration or by postoperative CT angiography at
outside institution. Axial early venous phase image (A) and sagittal
multiplanar reformation (B) from IV contrast-enhanced MDCT reveal
2.5-cm aneurysm posterior to pancreas and adjacent residual retroperitoneal
and intraperitoneal hemorrhage.
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Fig. 7C —45-year-old man who presented with syncope due to spontaneous,
intraperitoneal hemorrhage while exercising, source of which was not
identified during surgical exploration or by postoperative CT angiography at
outside institution. Axial oblique volume rendering from superior viewing
orientation shows relationship of pseudoaneurysm to splenic artery. Aneurysm
and splenic artery were successfully embolized.
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Unlike splenic artery aneurysms, splenic artery pseudoaneurysms (Fig.
8A,
8B) will nearly always present
with symptoms. In a large review of the literature, only 2.5% of cases
presented incidentally [5]. The
most common presentations are abdominal pain (29.5%), hematochezia or melena
(26.2%), hemorrhage into the pancreatic duct (20.3%), and hematemesis (14.8%)
[5]. The risk of rupture of a
splenic artery pseudoaneurysm can be as high as 37%, with the mortality rate
approaching 90% when untreated
[19,
20]. Furthermore, both small
and large pseudoaneurysms are at risk for rupture
[5]. Prompt diagnosis and
treatment are therefore critical in the management of these patients.
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Fig. 8A —38-year-old woman with history of chronic pancreatitis who had known
pancreatic pseudocyst. Contrast-enhanced CT showed enlarging splenic artery
pseudoaneurysm. Axial (A) and coronal volume rendering (B) from
IV and oral contrast-enhanced venous phase MDCT reveal 4.6 x 3.3 cm
heterogeneous mass (white arrows) in region of pancreatic tail.
Central enhancing component is compatible with pseudoaneurysm surrounded by
acute hemorrhage. In addition, elongated, enhancing region was identified
extending from pseudoaneurysm into spleen (black arrows, B),
which was new from previous examination and interpreted as second
pseudoaneurysm. Patient underwent interventional coil embolization of
pseudoaneurysm and the spleen.
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Fig. 8B —38-year-old woman with history of chronic pancreatitis who had known
pancreatic pseudocyst. Contrast-enhanced CT showed enlarging splenic artery
pseudoaneurysm. Axial (A) and coronal volume rendering (B) from
IV and oral contrast-enhanced venous phase MDCT reveal 4.6 x 3.3 cm
heterogeneous mass (white arrows) in region of pancreatic tail.
Central enhancing component is compatible with pseudoaneurysm surrounded by
acute hemorrhage. In addition, elongated, enhancing region was identified
extending from pseudoaneurysm into spleen (black arrows, B),
which was new from previous examination and interpreted as second
pseudoaneurysm. Patient underwent interventional coil embolization of
pseudoaneurysm and the spleen.
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Diagnosis
Direct catheter angiography has been assumed to be the gold standard for
the diagnosis of splenic artery aneurysm and pseudoaneurysm. The high spatial
resolution of digital subtraction angiography allows imaging of small vessels,
and treatment can be performed concomitantly. However, this procedure requires
arterial puncture, with its associated complications. The use of gray-scale
and Doppler sonography for the diagnosis of splenic artery aneurysms has been
reported [21]. This technique
is operator-dependent and may be limited due to obesity, shadowing from bowel
gas, and arteriosclerosis
[22]. In addition, small
lesions can be missed on sonography because of limited spatial resolution
[23]. MRI and MR angiography
techniques have also been described, with improvements in spatial resolution
compared to sonography [23].
Limitations of MRI included its contraindication in patients with pacemakers
or aneurysm clips, those suffering from claustrophobia, and those unable to
hold their breath [23].
With current MDCT technology, patients can be imaged quickly during the
arterial phase, which is essential for detecting these lesions. Relative
contraindications to CT angiography include renal failure, poor IV access, and
allergy to contrast material. Current generation MDCT scanners are capable of
high spatial resolution and short breath-hold times. The high temporal
resolution facilitates acquisition of data during a purely arterial phase and
results in decreased motion artifact. For creation of 2D reformations, Jaffe
et al. [24] have shown the
importance of isotropic data sets from submillimeter detector thickness. Using
a 16-MDCT scanner with 0.625-mm detector thickness, the radiation dose was
minimally higher compared to both 16- and 8-MDCT scanners with 1.25-mm
detector thickness (mean, 21.4, 20.6, and 20.1 mSv, respectively). However,
the submillimeter detector thickness was the only one to provide truly
isotropic reconstructions with no compromise in spatial resolution. That study
also compared reformation thicknesses of 1-5 mm for multiplanar reformations.
The results showed that contrast-to-noise ratios increased with increasing
reformation thickness, and 2-3 mm thick coronal reformations were
qualitatively rated as superior
[24].
CT Appearance and Pitfalls
With respect to true aneurysms, the CT appearance reflects the pathologic
changes in the aneurysm. Splenic artery aneurysms can appear well defined and
homogeneous on contrast-enhanced CT (Figs.
2 and
3). Alternatively, mural
thrombus may be present (Fig.
5), and peripheral calcification is apparent in many cases (Figs.
4A,
4B and
5).
Three-dimensional rendering improves evaluation of the splenic artery,
readily distinguishing tortuous vessel from aneurysm. An additional pitfall on
axial images is misinterpreting an aneurysm as a solid pancreatic neoplasm.
The literature includes a number of case reports in which aneurysms of
mesenteric artery branches have mimicked pancreatic tumors on CT
[25-28].
Because islet cell tumors of the pancreas can be markedly hyperattenuating in
the arterial or pancreatic phase
[29,
30], an unruptured splenic
artery aneurysm may mimic one of these hypervascular masses. Using axial
images (Figs. 9A,
9B,
9C,
9D and
10A,
10B,
10C,
10D), and even on multiplanar
reformations in some cases (Fig.
9A,
9B,
9C,
9D), an aneurysm located in
pancreatic tissue can appear as a small, round hyperattenuating mass.
Three-dimensional renderings show the relationship of aneurysm to the splenic
artery (Figs. 9A,
9B,
9C,
9D and
10A,
10B,
10C,
10D,
10E).
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Fig. 9A —70-year-old woman with pancreatic body mass on CT and MRI performed
at another institution that was interpreted as probable islet cell neoplasm.
Axial contrast-enhanced arterial phase CT scan (A), coronal oblique
multiplanar reformation (B), coronal volume rendering (C), and
axial color-coded volume rendering from superior orientation (D) show
2-cm aneurysm arising from mid portion of splenic artery and abutting
pancreas. Comparison with study from 6 months earlier revealed interval
enlargement. Patient was successfully treated with interventional coil
embolization of proximal splenic artery and aneurysm.
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Fig. 9B —70-year-old woman with pancreatic body mass on CT and MRI performed
at another institution that was interpreted as probable islet cell neoplasm.
Axial contrast-enhanced arterial phase CT scan (A), coronal oblique
multiplanar reformation (B), coronal volume rendering (C), and
axial color-coded volume rendering from superior orientation (D) show
2-cm aneurysm arising from mid portion of splenic artery and abutting
pancreas. Comparison with study from 6 months earlier revealed interval
enlargement. Patient was successfully treated with interventional coil
embolization of proximal splenic artery and aneurysm.
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Fig. 9C —70-year-old woman with pancreatic body mass on CT and MRI performed
at another institution that was interpreted as probable islet cell neoplasm.
Axial contrast-enhanced arterial phase CT scan (A), coronal oblique
multiplanar reformation (B), coronal volume rendering (C), and
axial color-coded volume rendering from superior orientation (D) show
2-cm aneurysm arising from mid portion of splenic artery and abutting
pancreas. Comparison with study from 6 months earlier revealed interval
enlargement. Patient was successfully treated with interventional coil
embolization of proximal splenic artery and aneurysm.
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Fig. 9D —70-year-old woman with pancreatic body mass on CT and MRI performed
at another institution that was interpreted as probable islet cell neoplasm.
Axial contrast-enhanced arterial phase CT scan (A), coronal oblique
multiplanar reformation (B), coronal volume rendering (C), and
axial color-coded volume rendering from superior orientation (D) show
2-cm aneurysm arising from mid portion of splenic artery and abutting
pancreas. Comparison with study from 6 months earlier revealed interval
enlargement. Patient was successfully treated with interventional coil
embolization of proximal splenic artery and aneurysm.
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Fig. 10A —52-year-old woman with history of surgically corrected aortic
coarctation and 2 months of abdominal pain and weight loss. CT performed at
outside institution revealed two enhancing lesions in pancreas that were
interpreted as neuroendocrine tumors. (Reprinted with permission from Horton
KM, Hruban RH, Yeo C, Fishman EK. Multi-detector row CT of pancreatic islet
cell tumors. RadioGraphics 2006; 26:453-464
[30]). Repeat
contrast-enhanced arterial phase MDCT with axial images (A and
B), axial oblique maximum intensity projection from superior
orientation (C), and coronal color-coded volume renderings (D
and E) reveal that lesion is actually partially calcified aneurysm
arising from splenic artery and located in body of pancreas.
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Fig. 10B —52-year-old woman with history of surgically corrected aortic
coarctation and 2 months of abdominal pain and weight loss. CT performed at
outside institution revealed two enhancing lesions in pancreas that were
interpreted as neuroendocrine tumors. (Reprinted with permission from Horton
KM, Hruban RH, Yeo C, Fishman EK. Multi-detector row CT of pancreatic islet
cell tumors. RadioGraphics 2006; 26:453-464
[30]). Repeat
contrast-enhanced arterial phase MDCT with axial images (A and
B), axial oblique maximum intensity projection from superior
orientation (C), and coronal color-coded volume renderings (D
and E) reveal that lesion is actually partially calcified aneurysm
arising from splenic artery and located in body of pancreas.
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Fig. 10C —52-year-old woman with history of surgically corrected aortic
coarctation and 2 months of abdominal pain and weight loss. CT performed at
outside institution revealed two enhancing lesions in pancreas that were
interpreted as neuroendocrine tumors. (Reprinted with permission from Horton
KM, Hruban RH, Yeo C, Fishman EK. Multi-detector row CT of pancreatic islet
cell tumors. RadioGraphics 2006; 26:453-464
[30]). Repeat
contrast-enhanced arterial phase MDCT with axial images (A and
B), axial oblique maximum intensity projection from superior
orientation (C), and coronal color-coded volume renderings (D
and E) reveal that lesion is actually partially calcified aneurysm
arising from splenic artery and located in body of pancreas.
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Fig. 10D —52-year-old woman with history of surgically corrected aortic
coarctation and 2 months of abdominal pain and weight loss. CT performed at
outside institution revealed two enhancing lesions in pancreas that were
interpreted as neuroendocrine tumors. (Reprinted with permission from Horton
KM, Hruban RH, Yeo C, Fishman EK. Multi-detector row CT of pancreatic islet
cell tumors. RadioGraphics 2006; 26:453-464
[30]). Repeat
contrast-enhanced arterial phase MDCT with axial images (A and
B), axial oblique maximum intensity projection from superior
orientation (C), and coronal color-coded volume renderings (D
and E) reveal that lesion is actually partially calcified aneurysm
arising from splenic artery and located in body of pancreas.
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Fig. 10E —52-year-old woman with history of surgically corrected aortic
coarctation and 2 months of abdominal pain and weight loss. CT performed at
outside institution revealed two enhancing lesions in pancreas that were
interpreted as neuroendocrine tumors. (Reprinted with permission from Horton
KM, Hruban RH, Yeo C, Fishman EK. Multi-detector row CT of pancreatic islet
cell tumors. RadioGraphics 2006; 26:453-464
[30]). Repeat
contrast-enhanced arterial phase MDCT with axial images (A and
B), axial oblique maximum intensity projection from superior
orientation (C), and coronal color-coded volume renderings (D
and E) reveal that lesion is actually partially calcified aneurysm
arising from splenic artery and located in body of pancreas.
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The CT appearance of peripancreatic pseudoaneurysms arising from various
mesenteric artery branches has been described in small case series
[31,
32]. On CT, splenic artery
pseudoaneuryms have been identified in pseudocysts, appearing as focal regions
of enhancement in the low-density intracystic fluid
[31]. Peripancreatic
pseudoaneurysms may show increased attenuation on unenhanced scans, and the
perfused portion will enhance strongly after contrast infusion
[32]. This enhancing component
may be surrounded by thrombus (Fig.
6A,
6B) or hematoma (Fig.
8A,
8B).
Treatment and Management
Aneurysms and pseudoaneurysms of the splenic artery require different
management strategies [33].
Most data suggest that treatment of symptomatic splenic artery aneurysms
should be performed [8]. In
addition, several high-risk groups should also be considered for repair, even
in the asymptomatic patient. In particular, pregnant women or women of
childbearing age should be considered for repair, as should patients with a
liver transplant or patients with cirrhosis and portal hypertension. However,
no consensus has been reached regarding intervention in asymptomatic patients
with splenic artery aneurysm. The smallest ruptured aneurysm over a 4-year
experience at the Mayo Clinic was 2 cm
[8]. Recommendations are to
treat asymptomatic aneurysms greater than 2 cm in patients with reasonable
operative risk and life expectancy greater than 2 years
[1,
8].
The appropriate treatment for splenic artery aneurysms depends on the
location of the lesion, the age of the patient, operative risks, and clinical
status. A greater than 0.5% operative mortality rate is associated with
elective repair, so it is imperative that patients be selected carefully
[17]. Aneurysms located in the
proximal or middle third of the splenic artery may be treated with simple
excision, with proximal and distal ligation of the artery and splenic
preservation (through the short gastric vessels). For aneurysms located in the
distal third, resection with splenectomy is most often performed
[33].
Recently, transcatheter embolization has been gaining favor
[34]. Although success rates
of approximately 85% are lower than those of direct surgical intervention,
associated operative morbidity and mortality rates are significantly reduced
[11].
Because of the high risk of rupture and the high mortality rate if splenic
artery pseudoaneurysm ruptures, the earliest possible intervention is deemed
necessary. As with symptomatic splenic artery aneurysms, splenectomy with or
without partial pancreatectomy has been the treatment of choice
[35]. Surgical intervention
carries mortality and morbidity risks of 1.3% and 9%, respectively
[35]. More recently,
transabdominal and endovascular techniques have reported variable success
rates [12,
35]. Endovascular techniques
using coils, detachable balloons, inert particles, or Gelfoam (gelatin sponge,
Upjohn) have reported success rates of 75-85%
[35]. Case reports describe
the use of percutaneous thrombin injection under CT guidance to treat splenic
artery pseudoaneurysms in patients who were not candidates for endovascular
therapy [12,
36]. In one case, partial
recanalization was identified on a 1-month follow-up CT, necessitating
reinjection [12]. Rare cases
of recanalization have been reported after endovascular embolization, so CT at
1 and 6 months after endovascular intervention has been advised
[35].
Conclusion
The exceptional resolution of 3D renderings from MDCT data sets will result
in identification of aneurysms and pseudoaneurysms that would have eluded
detection on older generation scanners. Three-dimensional renderings are
valuable for distinction from tortuous vessel or small, hyperattenuating islet
cell tumor of the pancreas. Clinical history can aid in distinguishing true
aneurysms from pseudoaneurysms; however, associated radiologic findings may be
identified to suggest pertinent coexisting disease. Specifically, concomitant
pancreatitis or peptic ulcer disease is a known causes of pseudoaneurysms.
Signs of cirrhosis, portal hypertension, or arteritis may be present in the
setting of true aneurysms. Once aneurysms or pseudoaneurysms are detected,
radiologists should promptly communicate the size, exact location (proximal,
mid, or distal splenic artery), and any indicators of rupture because these
factors affect management decisions.
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Abstract
Introduction
