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)