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Gastrointestinal Carcinoid Tumor: The Role of CT and MR G Ballester MD, C Llorens MD, E Tamm MD, P Bhosale MD, F Moron MD, J Szklaruk , MD, PhD
The University of Texas MD Anderson Cancer Center
Purpose 1. To present imaging protocols and the role of newer imaging techniques
in the diagnosis, staging, and management of patients with
gastrointestinal carcinoid tumors.
2. To present the MR and CT imaging findings of gastrointestinal carcinoid
tumors with special attention to the detection of the primary tumor,
desmosplastic reaction and metastatic disease.
Clinical Background • Carcinoids are malignant
neuroendocrine tumors arising
from enterochromaffin cells of
Kulchitsky in the crypts of
Lieberkuhn.
• 5th – 6th decade
• African-Americans >>> Whites
• Women > Men
• 2% of GI tract tumors
• Appendix (50-70%)
• Small bowel (20-30%) –
terminal ileum
• 30% are multiple
• 40-80% of small bowel
carcinoids spread to the
mesentery at the time of
diagnosis.
T – Primary Tumor
• TX - Primary tumor cannot be
assessed
• T0 - No evidence of primary
tumor
• T1 - Tumor invades lamina
propria (1a) or submucosa
(1b) and size ≤1 cm
• T2 - Tumor invades
muscularis propria or size
>1 cm
• T3 - Tumor invades into
subserosa, mesentery or
retroperitoneum; extension
< 2cm*
• T4 - Tumor invades
peritoneum or other organs*
• For any T, add (m) for
multiple tumors
• N – Regional Lymph Nodes
• NX – Regional lymph nodes
cannot be assessed
• N0 – No regional lymph
node metastasis
• N1 – Regional lymph node
metastasis with 1 – 3
lymph nodes involved*
• N2 – Regional lymph node
metastasis with 4 or more
lymph nodes involved*
• M – Distant Metastases
• MX – Distant metastases
cannot be assessed
• M0 – No distant
metastasis*
• M1 – Distant metastases*
Staging (TNM) – Small Bowel Carcinoid
Imaging Protocol: MDCT/DECT
Primary Tumor: DECT and MDCT
(a) 70keV Late Arterial (b) Iodine – Water Image
(d) 70keV 40% at Late Arterial (c) 50 keV Late Arterial
DECT of the pelvis
during the late arterial
phase of contrast
administration with axial
images (a) at 70 keV, (b)
Iodine-Water material
decomposition, (c) 50
KeV, and (d) 70 KeV at
40% ASIR. There is an
enhancing mass that
represents the primary
tumor in the distal
ilieum (arrows). This
patient had stage IV
disease due to liver
metastases.
Lymphatic Spread: DECT and MDCT
Imaging: MRI Findings
Axial post contrast MDCT images
of the pelvis show an enhancing
mass in the ileocecal region
(arrow). There are several dilated
small bowel loops (*) representing
partial bowel obstruction secondary
to the primary tumor.
Teaching Point
• The contrast between primary tumor and bowel is best on
the iodine(-water) MD images and 50keV images.
• Identification of the likely primary assists in surgical planning.
Surgical outcome is improved when all possible sites are
resected (primary, nodal, etc.)
Teaching Point
• Negative oral contrast
increases contrast between
lesion and bowel.
* *
• Most commonly asymptomatic
(90%).
• Carcinoid syndrome = Metastatic
spread to the liver
• 10% of patients
• Episodic flushing, diarrhea,
dyspnea, abdominal pain
• Symptoms require systemic
circulation of secretory factors
produced by carcinoid.
• Serotonin, somatostatin,
glucagon, histamine,
dopamine, VIP, gastrin
• MEN 1 mutation (10% of carcinoids)
• Duodenal and jejunal carcinoids
• 30-50% of patients develop a 2nd
primary (GI or GU adenocarcinoma))
*Imaging plays a role in
Staging of T3 and T4
*Imaging plays a role in
Staging of N0, N1, and N2
*Imaging plays a role in
Staging of M0 vs. M1
Stage I T1-T2 N0 M0
Stage IIa T3 N0 M0
Stage IIb T4 N0 M0
Stage IIIa Any T N1 M0
Stage IIIb Any T N2 M0
Stage IV Any T Any N M1
Diagram demonstrates multiple liver
metastases (M1), and multiple
primary tumors in the small bowel
(black arrow); representing T2
tumor. There is also a central
desmoplastic mesenteric mass (blue
arrow) with associated bowel
retraction in keeping with lymphatic
spread (N1). This represents Stage
IV carcinoid tumor.
• Pre-Contrast
– 5mm/2.5mm reconstruction
– Negative GI contrast:
• 0.1% barium sulfate (Volumen) or water
• Improves detection secondary to bowel distention and improving conspicuity of hyperenhancing lesions.
• Late Arterial phase – 1st injection – 125-150 ml @ 5 ml/s
• Threshold at celiac artery – 100 HU 10 sec delay
– 2.5 mm & 0.625 mm axial recons – Dual energy (DECT) is typically
applied to this phase – Iodine material density (MD),
70 and 50 keV axial images • Venous phase
– 50-60 seconds post-injection – 2.5 mm & 0.625 mm axial recons
• Delayed phase (optional) – 120 sec post-injection – 2.5 mm & 0.625 mm recons
• Primary Tumor
• Solitary or multiple, well-
defined early enhancing
lesion(s) in the bowel wall.
• Optimum visualization with a
negative contrast oral agent
(0.1% barium or water).
• Lymphatic Spread
• Mesenteric mass
• Ill-defined, spiculated
heterogeneous mass.
• 70% contain calcifications
• Desmoplastic reaction
• Hematogenous Spread
• Liver metastases
• Variably intense late
arterial enhancement
• Become isodense on
portal phase and
hypodense on delayed
venous phase
• Peritoneal spread
• Late development.
• Small, discrete nodular
lesions, without
significant ascites.
Imaging Findings: MDCT and DECT
(a) Coronal and (b) Axial
post-contrast DECT of
the pelvis. The coronal
image show a
mesenteric mass with
calcification (arrow
head) along the ileocolic
nodal station. The
primary tumor is seen
nearby on the axial post-
contrast image (arrow)
[see also prior figure].
Teaching Point
• With DECT, there is improved contrast between
lymphadenopathy and the background mesenteric fat.
• Detection of the mesenteric nodal mass aids in the localization
of the primary tumor.
(a) (b)
Hematogenous Spread: DECT and
MDCT
(a) 70kEV Late Arterial (b) 50kEV Late Arterial
(c) Water - Iodine (d) Iodine-Water
Axial images of DECT of the liver
during the late arterial phase of
contrast administration
reconstructed at (a) 70keV, (b)
50KeV, (c) as a Water – iodine
material decomposition (MD)
Image, and as (d) Iodine – water
MD Image. There are multiple
bilobar hepatic metastatic
lesions (arrows).
Teaching Point
• Contrast between lesion
and background tissue can
be improved with DECT
imaging.
Axial post contrast late arterial
phase MDCT image of the
abdomen shows a metastatic
mass in the left adrenal gland
(yellow arrow). There is also
metastatic disease to the liver
(arrowhead). The primary tumor
located in the stomach is poorly
visualized (orange arrow).
Teaching Point
• Metastatic disease may be seen outside the liver.
• The primary tumor is poorly visualized with the use of a
positive oral contrast agent.
Imaging Protocol: MRI Abdomen
* For the detection of liver metastases, MR studies at out institution for patients with the diagnosis of carcinoid are preferentially performed with Eovist (gadoxetate disodium, Bayer AG, Berlin) .
•Dynamic Imaging - LAVA or VIBE
• Pre-contrast
• Post – Contrast
• Late Arterial phase
• 17s to center K-space after
visualization of pulmonary artery
• Venous phase •50-60 s post-injection
•Equilibrium phase
•120 s post-injection
•Delayed Phase
•5 min post-injection
•Hepatobiliary Phase*
•20 min post-injection of Eovist
•Cor SSFSE or HASTE
•In-Phase and OOP T1
•Ax T2 Respiratory Triggered
•DWI
• (B – 50 & 800 sec/mm2)
• Primary Tumor
• T1WI – isointense to muscle
• T2WI – iso or hyperintense to
muscle
• T1 Gd+ - heterogeneous early
enhancement
• Lymphatic Spread
• T1WI - mesenteric mass iso to
muscle with hypointense
desmoplastic strands
• T2WI - mesenteric mass iso to
hyper intense to muscle with
hypointense desmoplastic strands
• DWI – Restricted diffusion
• T1 Gd+ - Enhancement
• Hematogenous Spread
• T1WI – hypointense to
liver
• T2WI – hyperintense to
liver
• DWI – Restricted
diffusion
• T1 - (extracellular agent) -
homogeneous late
arterial enhancement;
heterogeneous/peripheral
enhancement in larger
lesions
• T1 Hepatobiliary Phase –
hypointense to liver
Lymphatic Spread: MRI
Hematogenous Spread: MRI
(a) T1WI Out-of-Phase (b) T2WI
(c) Late Arterial Post-Gd (d) Hepatobiliary Phase
(e) DWI B – 800 sec/mm2 (f) ADC MAP
MRI of the abdomen. (a) Axial T1W
OOP, (b) Axial T2WI, (c) Axial post-
Eovist Late Arterial phase, (d) Axial
post-Eovist Hepatobiliary Phase, (e)
Axial DWI (B = 800sec/mm2), and (f)
Axial ADC Map. There is a
mesenteric mass (arrows) with
spiculation and retraction. The
retraction represents the desmoplastic
reaction.
Teaching Point
• Lymphatic spread shows
optimum contrast on the
DWI; high B-values. There is
confirmation of restricted
diffusion on the ADC map.
• The post-Gd images show
enhancement on the late
arterial phase. On the
hepatobiliary phase the mass
is isointense to muscle.
(a) T1WI In-Phase (b) T2WI
(d) Early Arterial Post-Gd
(e) Hepatobiliary Phase (f) DWI B – 500 sec/mm2
(c) Pre-Contrast
MRI of the abdomen. (a) Axial T1W IP (b) Axial T2WI, (c) Axial Pre-Contrast and (d) Post-Eovist Early Arterial Phase, (e) Axial Post-Eovist Hepatobiliary Phase, (f) Axial DWI ( B = 500sec/mm2). There is restricted diffusion. There is a metastatic mass in the right liver (arrows). There is a cyst in segment II of the liver (arrowhead).
Teaching Point
• The metastasis enhances in
the late arterial phase of
contrast administration.
• The metastasis is better
defined in the hepatobiliary
phase.
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Axial post contrast MDCT images of the
pelvis in a patient with rectal carcinoid
tumor. The lymphatic spread is seen as a
solid mass in the perirectal nodal station
(a, arrowhead). The primary tumor is
identified in the rectum (b, arrow).
Teaching Point
• Detection of lymphangitic spread
aids in localization of the primary
tumor.
• The primary mass may mimic
benign or malignant etiology on
routine post-contrast images. DDx
includes rectal cancer, adenoma, or
even fecal residue.
(a)
(b)
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