DOI:10.2214/AJR.05.0941
AJR 2006; 187:1204-1211
© American Roentgen Ray Society
Spectrum of Imaging Findings in the Abdomen After Radiotherapy
Jin-Wei Kwek1,2,
Revathy B. Iyer2,
Joel Dunnington1,
Silvana Faria1 and
Paul M. Silverman1
1 Department of Diagnostic Imaging, Unit 57, University of Texas M. D. Anderson
Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030-4009.
2 Present address: Department of Diagnostic Radiology, Tan Tock Seng Hospital,
Singapore, Republic of Singapore.
Received June 2, 2005;
accepted after revision July 25, 2005.
Address correspondence to R. B. Iyer.
Abstract
OBJECTIVE. The objective of this article is to describe the imaging
appearances of radiation injury to normal tissues in the abdomen that may be
seen during imaging surveillance of oncology patients.
CONCLUSION. Therapeutic radiation is used to treat various malignant
conditions in the abdomen. Radiation damages normal surrounding tissues as
well as the intended tumor. Radiation changes vary based on the target organ
and the time from completion of therapy. Familiarity with the spectrum of
changes that may be seen on follow-up imaging studies should help in the
differentiation of radiation injury from other causes such as recurrent
malignancy.
Keywords: CT • gastrointestinal system • kidney • liver • musculoskeletal system • pancreas • radiation injury • radiotherapy • stomach • vascular injury
Introduction
Radiation therapy is used to cure malignancy, as adjuvant therapy, and for
palliation. Abdominal tumors that are typically treated include lymphoma and
gastroesophageal and pancreatic carcinomas. The risk of injury depends on the
size, number, and frequency of radiation fractions; volume of irradiated
tissue; duration of treatment; and method of radiation delivery. Concomitant
chemotherapy can act synergistically to produce injury
[1]. Other predisposing factors
include infection, prior surgery, and chronic illness (e.g., hypertension,
diabetes mellitus, and atherosclerosis). Radiation changes vary based on the
target organ and the time from completion of therapy. Familiarity with the
spectrum of imaging findings after radiation injury permits differentiation
from other causes such as recurrent malignancy. This pictorial essay
illustrates findings that may be encountered when imaging patients after
therapeutic irradiation.
Solid Viscera
The liver is usually included during radiation treatment to the stomach,
pancreas, and thoracolumbar spine. The tolerance of the whole liver is 30-35
Gy in conventional fractionation, but parts of the liver can be treated with
doses in excess of 70 Gy with 3D radiation therapy treatment planning.
Radiation-induced liver disease (RILD), or radiation hepatitis, is a clinical
syndrome of anicteric ascites and hepatomegaly occurring 2 weeks to 4 months
after hepatic irradiation as a result of venoocclusive disease
[1]. The irradiated liver
appears hypodense on unenhanced CT scans. This CT finding can also be seen in
patients who receive more than 45 Gy to a portion of the liver, regardless of
whether they develop RILD. Patients are usually asymptomatic if the
nonirradiated liver is healthy. The irradiated liver is hypodense with
well-defined linear margins that conform to radiation portals (Figs.
1A,
1B,
1C, and
1D). In a fatty liver, the CT
density pattern may be reversed (Figs.
2A and
2B). The irradiated area can
enhance more than adjacent liver because of increased arterial flow or delayed
clearance of contrast material from radiation-induced venoocclusive disease.
On MR images, increased water within the irradiated liver causes T1-weighted
hypointensity and T2-weighted hyperintensity (Figs.
3A,
3B,
3C, and
3D).
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Fig. 1A —39-year-old woman with adenocarcinoma of gastric antrum, She
underwent preoperative neoadjuvant 5-fluorouracil and paclitaxel-based
chemoradiation with 45 Gy of radiation in 25 fractions 1 month ago, followed
by distal gastrectomy and Billroth type II gastrojejunostomy. Irradiated area
of left lobe (A) of liver appears hypodense on unenhanced CT with linear
margin (arrowheads) corresponding to radiation portal.
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Fig. 1B —39-year-old woman with adenocarcinoma of gastric antrum, She
underwent preoperative neoadjuvant 5-fluorouracil and paclitaxel-based
chemoradiation with 45 Gy of radiation in 25 fractions 1 month ago, followed
by distal gastrectomy and Billroth type II gastrojejunostomy. Axial CT scan in
arterial phase of contrast enhancement better shows linear margin
(arrowheads) corresponding to radiation portal.
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Fig. 1C —39-year-old woman with adenocarcinoma of gastric antrum, She
underwent preoperative neoadjuvant 5-fluorouracil and paclitaxel-based
chemoradiation with 45 Gy of radiation in 25 fractions 1 month ago, followed
by distal gastrectomy and Billroth type II gastrojejunostomy. Irradiated area
of left lobe of liver (A) remains hypodense (arrowheads) compared
with adjacent healthy liver in portal venous phase.
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Fig. 1D —39-year-old woman with adenocarcinoma of gastric antrum, She
underwent preoperative neoadjuvant 5-fluorouracil and paclitaxel-based
chemoradiation with 45 Gy of radiation in 25 fractions 1 month ago, followed
by distal gastrectomy and Billroth type II gastrojejunostomy. Follow-up CT 1
year later shows mild atrophy of irradiated left lobe of liver (A).
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Fig. 2A —44-year-old woman with metastatic breast carcinoma and
radiation therapy for T12 metastasis. Unenhanced CT scan shows well-demarcated
band of hyperattenuation in medial portions of left and right lobe of liver
(arrowheads). Adjacent nonirradiated liver is hypoattenuating because
of fatty replacement. This is reversal of density pattern noted in Figures
1A,
1B,
1C, and
1D.
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Fig. 2B —44-year-old woman with metastatic breast carcinoma and
radiation therapy for T12 metastasis. During portal venous phase, increased
enhancement of irradiated portion of liver (arrowheads) is seen
compared with nonirradiated liver.
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Fig. 3A —50-year-old woman with metastatic breast carcinoma. She
underwent left mastectomy and axillary lymph node dissection and was treated
with radiation therapy for metastasis to T12 vertebral body. Axial CT scan
shows sclerotic-treated metastasis at T12 vertebral body (arrow).
Note well-demarcated band of hypoattenuation in right and left lobe of liver
corresponding to radiation portal (arrowheads).
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Fig. 3B —50-year-old woman with metastatic breast carcinoma. She
underwent left mastectomy and axillary lymph node dissection and was treated
with radiation therapy for metastasis to T12 vertebral body. Axial T1-weighted
MR image shows reduced signal intensity within irradiated portion of liver
(arrowheads). Fatty marrow replacement of lower T12 vertebra is noted
(arrow).
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Fig. 3C —50-year-old woman with metastatic breast carcinoma. She
underwent left mastectomy and axillary lymph node dissection and was treated
with radiation therapy for metastasis to T12 vertebral body. Irradiated medial
portion of liver appears hyperintense in axial T2-weighted image, related to
increased water content (arrowheads).
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Fig. 3D —50-year-old woman with metastatic breast carcinoma. She
underwent left mastectomy and axillary lymph node dissection and was treated
with radiation therapy for metastasis to T12 vertebral body. Sagittal
T1-weighted image shows fatty marrow replacement of thoracolumbar spine with
hypointense-treated metastasis at T12 vertebral body (arrows).
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The spleen may be irradiated to treat lymphoma, splenomegaly, and
hypersplenism. It is very radiosensitive, and lymphoid tissues are destroyed
within hours after a dose of 4-8 Gy
[2,
3]. At doses of 35-40 Gy,
splenic fibrosis and atrophy may result
(Fig. 4). The effects of
splenic irradiation are usually not clinically significant, although
functional hyposplenism and fulminant pneumococcal sepsis can occur.
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Fig. 4 —65-year-old man with history of gastric lymphoma and
radiation therapy 3 years ago. Axial CT scan shows focal area of splenic
infarct (S), diffuse pancreatic atrophy (arrowheads), and atrophy of
upper pole of left kidney (arrow).
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Irradiation to the pancreas causes necrosis and fibrosis similar to chronic
pancreatitis. The pancreatic acinar epithelium is more sensitive than the
islet cells [2]. Imaging
features are also similar to chronic pancreatitis
(Fig. 4).
Kidneys and Ureters
The kidney is radiosensitive, and 28 Gy to both kidneys in 5 weeks or less
frequently leads to renal failure. A dose of 17 Gy in 5 weeks or more is
better tolerated if patient has no preexisting renal impairment. The risk of
renal impairment increases with prior or concurrent chemotherapy. In acute
radiation nephritis, the kidney remains normal in size and shape, although
glomerular damage is present histologically. Radiologic changes appear months
to years after treatment, ultimately resulting in atrophic poorly functioning
but unobstructed kidneys with smooth outlines. Compensatory hypertrophy of the
nonirradiated contralateral kidney can develop. If only a portion of the
kidney is irradiated, only that portion is affected (Figs.
5A,
5B,
6A, and
6B). Malignant hypertension
may develop 1 to 10 years after renal irradiation, requiring nephrectomy
relief. The ureter is fairly radioresistant, and radiation-induced strictures
are infrequent [4].
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Fig. 5A —42-year-old woman with ovarian cancer, treated with radiation
therapy for retroperitoneal lymphadenopathy. Excretory urogram obtained before
radiation therapy shows both kidneys with normal size and configuration and
symmetric excretion of contrast material.
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Fig. 5B —42-year-old woman with ovarian cancer, treated with radiation
therapy for retroperitoneal lymphadenopathy. Second excretory urogram obtained
4 years after radiation therapy shows focal atrophy of upper poles of both
kidneys (arrows). Outlines of both kidneys remain smooth.
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Fig. 6A —51-year-old woman with metastatic breast carcinoma to porta
hepatis who underwent 36 Gy of external beam irradiation. Equilibrium phase CT
scan shows well-demarcated band of hyperattenuation in medial portion of right
lobe of liver (arrowheads) corresponding to radiation portal.
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Fig. 6B —51-year-old woman with metastatic breast carcinoma to porta
hepatis who underwent 36 Gy of external beam irradiation. Follow-up CT 53
months later, shows focal atrophy of upper pole of right kidney
(arrow) and focal atrophy of irradiated portion of liver
(arrowheads).
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Gastrointestinal System
The stomach and duodenum may be injured when the target is retroperitoneal
lymphadenopathy or the pancreas. Radiographic findings include prepyloric and
pyloric ulcers with deformity, which are indistinguishable from benign peptic
ulceration except that the former may not heal. Fixed narrowing, deformity,
and an aperistaltic antropyloric region without ulceration can also occur
[5]. On CT, nonspecific wall
thickening is observed (Figs.
7A and
7B), occasionally with
perigastric stranding.
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Fig. 7A —76-year-old woman with locally advanced carcinoma of
pancreas. She underwent preoperative chemoradiation, with dose of 30 Gy at 3
Gy per fraction for 10 fractions. Contrast-enhanced axial CT scan 2 months
later shows focal wall thickening of antropyloric region of stomach
(arrowheads) and gallbladder (curved arrow). Primary tumor
in head of pancreas (short wide arrow) is causing obstruction of
common bile duct, and biliary stent (long thin arrow) has been
inserted to decompress biliary system.
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Fig. 7B —76-year-old woman with locally advanced carcinoma of
pancreas. She underwent preoperative chemoradiation, with dose of 30 Gy at 3
Gy per fraction for 10 fractions. Axial CT scan at lower section shows focal
wall thickening of hepatic flexure of colon (arrow). Colonoscopy and
biopsy proved radiation injury.
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The small intestine is quite radiosensitive and is potentially in the
treatment field for all intraabdominal and retroperitoneal tumors. The
terminal ileum is more commonly injured because it is more fixed. Acutely,
small-bowel dilation with edema and mucosal sloughing can occur and usually
resolves. Chronic bowel injury is caused by submucosal obliterative vasculitis
that results in ischemia and fibrosis
[5]. Fibrotic strictures may
cause small-bowel obstruction. Complex fistulas are late features. Similar
findings occur in the colon (Figs.
7A and
7B). Late changes of
mesenteric fibrosis result in fixation of small bowel loops with tethering,
sometimes elicited only by careful spot compression during fluoroscopy. CT
findings reflect fluoroscopic findings (Figs.
8A and
8B) and can exclude tumor
recurrence as the cause. CT is also useful in identifying extraluminal air or
contrast medium in fistulas.
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Fig. 8A —63-year-old man with sigmoid colon carcinoma recurrence.
Unenhanced axial CT scan shows retroperitoneal lymphadenopathy
(arrows in A and B) causing right hydroureter
(curved arrow). He was treated palliatively with external beam
irradiation, 30 Gy in 10 fractions.
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Fig. 8B —63-year-old man with sigmoid colon carcinoma recurrence.
Follow-up unenhanced CT scan 1 month later shows wall thickening and edema in
ileal loops (arrowheads) in radiation portal. Ureteric stent is noted
in decompressed right ureter (curved arrow).
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Vascular Injury
Radiation injury differs in small and large vessels. The endothelia of
microvessels are the most radiosensitive, and severe damage results in
intracellular edema with resultant vascular occlusion. Less severe damage
results in telangiectasia. Arteriolar damage is frequent and consists of
myointimal proliferation indistinguishable from atherosclerosis. Acute
lymphocytic vasculitis affecting the media, intima, and adventitia of
medium-size vessels is also observed. In medium and large arteries, atheromas
and fibrosis are observed less often, resulting in stenosis (Figs.
9A and
9B). Rupture of irradiated
large vessels occurs mostly in the carotid arteries and less frequently in the
aorta and femoral arteries
[6].
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Fig. 9A —47-year-old woman with adenocarcinoma of cervix, treated with
external beam irradiation to retroperitoneal lymphadenopathy 3 years earlier.
Angiogram of abdominal aorta shows marked stenosis of distal aorta and
bilateral common, internal, and external iliac arteries (arrowheads).
Note enlarged collateral lumbar arteries at L3 and L4 (arrows). Tip
of catheter is in distal aorta.
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Fig. 9B —47-year-old woman with adenocarcinoma of cervix, treated with
external beam irradiation to retroperitoneal lymphadenopathy 3 years earlier.
Axial CT scan shows narrowing of distal aorta with calcified atheromatous
plaques (arrow). No surrounding mass, which would suggest tumor
recurrence, is present.
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Fig. 10 —41-year-old woman with history of radiation therapy for
neuroblastoma involving her spine at 15 months old. She developed transitional
cell carcinoma of bladder at age of 37 years and underwent radical cystectomy
with bilateral pelvic lymph node dissection and chemoradiation. Excretory
urogram shows Indiana pouch (P) urinary diversion. Also note atrophy of right
side of lumbar vertebrae with resultant scoliosis with concavity to right,
caused by radiation injury to growing skeleton during childhood.
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Musculoskeletal System
In children, the spine may be irradiated for Wilms' tumor, neuroblastoma,
Hodgkin's lymphoma, and acute lymphocytic leukemia with CNS relapse. This
often results in inhibition of vertebral growth and short stature, and
kyphoscoliosis may result from asymmetric irradiation (Figs.
10,
11A, and
11B). Osteitis and secondary
fractures may also be observed (Figs.
12A and
12B).
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Fig. 11A —18-year-old man treated with 34 Gy from T4 to L1 16 years
earlier for neuroblastoma involving lower thoracic and upper lumbar spine.
Anteroposterior (A) and lateral (B) radiographs of spine show
marked kyphoscoliosis of thoracolumbar spine.
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Fig. 11B —18-year-old man treated with 34 Gy from T4 to L1 16 years
earlier for neuroblastoma involving lower thoracic and upper lumbar spine.
Anteroposterior (A) and lateral (B) radiographs of spine show
marked kyphoscoliosis of thoracolumbar spine.
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Fig. 12B —3-year-old boy with Wilms tumor treated with external beam
radiation therapy. Lateral radiograph of lumbar spine performed 14 years later
shows wedging of T12-L4 vertebral bodies, which is compatible with compression
fractures.
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In adults, the spine is usually irradiated for metastatic disease. Acutely,
edema and necrosis of the marrow result in increased T2-weighted signal
intensity within days. Conversion to fatty marrow results in T1-weighted
hyperintensity (Figs. 3A,
3B,
3C, and
3D), occurring as early as 2
weeks after therapy and completed by 6 to 8 weeks in 90% of patients
[7].
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Fig. 13A —79-year-old man treated with radiation therapy 25 years ago
presented with radiation-induced rhabdomyosarcoma of erector spinae muscles.
Contrast-enhanced CT scan shows midline soft-tissue mass in erector spinae
muscles (arrows) with involvement of spinous process of adjacent L3
lumbar vertebra.
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Fig. 13B —79-year-old man treated with radiation therapy 25 years ago
presented with radiation-induced rhabdomyosarcoma of erector spinae muscles.
Sagittal contrast-enhanced T1-weighted MRI scan shows tumor mass extension
into spinal canal at L3 with anterior displacement of nerve roots in thecal
sac (arrowheads).
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Radiation-induced tumors include bone and soft-tissue sarcoma, lymphoma,
and mesothelioma. The mean latency period for postradiation sarcomas ranges
from 4 to 17 years [8]. The
most common imaging findings are soft-tissue mass and bone destruction (Figs.
13A and
13B). Although imaging
findings are not specific, appreciation of the long latency period after
radiation therapy may help suggest the diagnosis.
References
- Lawrence TS, Robertson JM, Anscher MS, Jirtle RL, Ensminger WD,
Fajardo LF. Hepatic toxicity resulting from cancer treatment. Int J
Radiat Oncol Biol Phys 1995;31
: 1237-1248[CrossRef][Medline]
- Charnsangavej C, Cinqualbre A, Wallace S. Radiation changes in the
liver, spleen, and pancreas: imaging findings. Semin
Roentgenol 1994; 29:53
-63[CrossRef][Medline]
- Wallace S. Liver, spleen, and pancreas. In: Libshitz H, ed.
Diagnostic roentgenology of radiotherapy change.
Baltimore, MD: Williams and Wilkins, 1979:101
-109
- Libshitz H, Green B. Kidney. In: Libshitz H, ed.
Diagnostic roentgenology of radiotherapy change.
Baltimore, MD: Williams and Wilkins, 1979:111
-122
- DuBrow RA. Radiation changes in the hollow viscera.
Semin Roentgenol 1994;29
: 38-52[CrossRef][Medline]
- Fajardo LF. Is the pathology of radiation injury different in small
vs large blood vessels? Cardiovasc Radiat Med1999; 1:108
-110[CrossRef][Medline]
- Yankelevitz DF, Henschke CI, Knapp PH, Nisce L, Yi Y, Cahill P.
Effect of radiation therapy on thoracic and lumbar bone marrow: evaluation
with MR imaging. AJR 1991;157
: 87-92[Abstract/Free Full Text]
- Sheppard DG, Libshitz HI. Post-radiation sarcomas: a review of the
clinical and imaging features in 63 cases. Clin Radiol2001; 56:22
-29[CrossRef][Medline]
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Abstract
Introduction
