AJR 2005; 184:1293-1304
©
American Roentgen Ray Society
PET/CT in the
Evaluation of Childhood Sarcomas
M. Beth
McCarville1,2, Ryan Christie2,
Najat C. Daw3, Sheri L.
Spunt3 and Sue C. Kaste1,2,3
1
Department of Radiological Sciences, St. Jude Children's
Research Hospital, 332 N Lauderdale St., Memphis, TN
38105.
2 Department of Radiology, College of
Medicine, University of Tennessee, Memphis, TN.
3 Department of Hematology-Oncology, St. Jude
Children's Research Hospital, Memphis, TN.
Received July
9, 2004;
accepted after revision September 13, 2004.
Address
correspondence to M. B. McCarville.
Supported in
part by Cancer Center Support grant CA21765 from
the U.S. Public Health Service, by Childhood Solid
Tumor Program Project grant CA-23099 and by
the American Lebanese Syrian Associated
Charities.
Abstract
OBJECTIVE. Our objective was to review our
preliminary experience with PET/CT in
evaluating childhood sarcomas including rhabdomyosarcoma
(n = 28), the Ewing's sarcoma family
of tumors (n = 14), nonrhabdomyosarcoma
soft-tissue sarcoma (n = 9), osteosarcoma (n
= 8), chondrosarcoma (n = 1), and
embryonal sarcoma (n = 1).
CONCLUSION. We found PET/CT useful in
depicting an unknown primary rhabdomyosarcoma
and detecting unsuspected and unusual metastatic sites
of childhood sarcomas. It was useful in
monitoring response to chemotherapy, radiation
therapy, and radiofrequency ablation and aided the
postoperative evaluation of tumor resection
sites.
Introduction
Fluorine-18 FDG is a radiolabeled glucose
analogue that is transported across cell
membranes and phosphorylated but cannot be
dephosphorylated. As a result, FDG is trapped
inside cells, where it emits a positron that
undergoes an annihilation reaction with an electron to
produce two 511-keV gamma rays, which are emitted
in opposite directions. When a PET camera
detects two 511-keV photons of energy coming
from opposite directions at the same time, a signal
is produced. PET of this nature capitalizes on the
fact that tumors are highly metabolically
active and accumulate more glucose (and FDG)
than normal tissue [1,
2]. Currently FDG PET has been
approved for Medicare reimbursement in the
evaluation of adults with lymphoma, solitary
pulmonary nodules, lung cancer, colorectal
cancer, esophageal cancer, melanoma, head and neck
cancer, and breast cancer [1,
2]. The utility of PET for pediatric
oncologic applications, other than Hodgkin's
lymphoma, has not been well evaluated.
Since 2002, we have performed PET/CT as part of the
imaging evaluation of 61 children with a
variety of sarcomas, including
rhabdomyosarcoma (n = 28), Ewing's sarcoma family
of tumors (n = 14),
nonrhabdomyosarcoma soft-tissue sarcomas (n = 9),
osteosarcoma (n = 8), chondrosarcoma (n
= 1), and embryonal sarcoma (n = 1).
PET/CT provides a method of obtaining both
metabolic and morphologic information in one imaging
session. Generally, a low-dose CT scan is
obtained first and is used to determine
attenuation correction factors for PET and also serves
as an anatomic reference. Immediately after
acquisition of the CT scan, a PET scan is
obtained without moving the patient. This
allows accurate coregistration of PET and CT images. The
images are reviewed at a workstation that allows
one to view the CT images alone, the PET
images alone, and the CT images fused with
the corresponding PET images in a side-by-side format.
This hybrid technique has an important advantage
over PET alone because it allows accurate
anatomic localization of sites of increased
FDG activity. The purpose of this pictorial essay
is to review our preliminary experience with this
fusion imaging technique in the evaluation of
childhood sarcomas. We will illustrate and
discuss applications of PET/CT that have been of benefit
to us and may ultimately enhance the management of
these malignancies.
Identification of an Unknown Primary Site
Although most sarcomas are evident on physical
examination, it is estimated that 4% of
rhabdomyosarcomas and 3-5% of all cancers
present with metastatic disease and an unknown primary
site [3, 4].
The imaging evaluation of such patients is focused
on identifying the primary site and is guided by
both clinical suspicion and the pathologic
type of metastatic disease [3,
4]. Traditionally such
evaluations could require the use of multiple
imaging techniques suitable for assessing various
anatomic sites. PET/CT allows evaluation of
the entire patient in one sitting. PET has
been shown to reveal the location of primary tumors
in 21-30% of adults with occult head and neck or
breast cancers but has also been shown to
have a false-positive rate of approximately
20% in these patients [3]. PET/CT
may reduce this false-positive rate because
it allows sites of physiologically increased FDG
activity (e.g., supraclavicular brown fat) to be
accurately localized and distinguished from
tumor-based activity. We found PET/CT useful
in identifying an unknown primary site in a child
with widely metastatic alveolar rhabdomyosarcoma
(Figs. 1A, and
1B).
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Fig.
1A. —12-year-old girl who
presented with abdominal
lymphadenopathy, anemia, and pleural
effusion. Differential diagnosis
included Burkitt's lymphoma versus solid
tumor. Bone marrow biopsy revealed
alveolar rhabdomyosarcoma. Primary site
was not identified at physical
examination.
Maximum-intensity-projection PET image
revealed primary site in left calf (arrow).
Note also diffuse bone marrow metastatic
disease evidenced by increased activity
throughout skeleton relative to liver.
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Fig.
1B. —12-year-old girl who
presented with abdominal
lymphadenopathy, anemia, and pleural
effusion. Differential diagnosis
included Burkitt's lymphoma versus solid
tumor. Bone marrow biopsy revealed
alveolar rhabdomyosarcoma. Primary site
was not identified at physical
examination. Contrast-enhanced axial MRI
of left calf primary tumor was obtained
after PET/CT. This deeply seated tumor
(T) was missed at initial physical
examination.
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Initial Staging of a Sarcoma
The baseline imaging evaluation of bone and soft-tissue
sarcomas in children currently includes MRI
of the primary tumor, CT of the chest to
evaluate pulmonary metastases, and
technetium-99m-labeled methyldiphosphonate (99mTc
MDP) nuclear scintigraphy to identify bony
metastatic disease [5]. In tumors
with a propensity for regional nodal spread,
such as rhabdomyosarcoma, MRI or CT of the
draining lymph nodes must also be performed. We have
found PET/CT useful in identifying and
localizing unusual sites of soft-tissue and
bony metastases not appreciated on physical examination
or imaging performed during the conventional
metastatic workup (Figs. 2A,
2B, 2C,
2D, and 2E). In
our experience, PET/CT has had limited
specificity in distinguishing benign and malignant
nodal disease (Figs. 3A,
3B, 3C,
3D, 3E,
3F, 4A,
4B, 4C,
4D, 4E,
4F, 4G,
4H, 4I,
5A, 5B,
5C, and
5D).
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Fig.
2A. —19-year-old woman who
presented with left thigh mass proven by
biopsy to be high-grade malignant
peripheral nerve sheath tumor. Anterior
maximum-intensity-projection PET image
shows primary left thigh tumor (straight
arrow), abnormal left pelvic
activity (arrowhead), and
abnormal focus in thoracic vertebra (curved
arrow).
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Fig.
2B. —19-year-old woman who
presented with left thigh mass proven by
biopsy to be high-grade malignant
peripheral nerve sheath tumor. STIR
sagittal MR image of spine shows only
subtle lesion (arrow)
corresponding to abnormal focus seen on
PET.
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Fig.
2C. —19-year-old woman who
presented with left thigh mass proven by
biopsy to be high-grade malignant
peripheral nerve sheath tumor. Axial CT
(C), PET (D), and fused
PET/CT (E) images show intense
activity in ninth thoracic vertebral
body (arrows), which was proven
by biopsy to be metastatic disease. Bone
metastases are very rare in malignant
peripheral nerve sheath tumor, and this
metastatic deposit was not clinically
suspected. Technetium-99m-labeled
methyldiphosphonate bone scan obtained
the day before PET showed no evidence of
disease in thoracic spine.
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Fig.
2D. —19-year-old woman who
presented with left thigh mass proven by
biopsy to be high-grade malignant
peripheral nerve sheath tumor. Axial CT
(C), PET (D), and fused
PET/CT (E) images show intense
activity in ninth thoracic vertebral
body (arrows), which was proven
by biopsy to be metastatic disease. Bone
metastases are very rare in malignant
peripheral nerve sheath tumor, and this
metastatic deposit was not clinically
suspected. Technetium-99m-labeled
methyldiphosphonate bone scan obtained
the day before PET showed no evidence of
disease in thoracic spine.
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Fig.
2E. —19-year-old woman who
presented with left thigh mass proven by
biopsy to be high-grade malignant
peripheral nerve sheath tumor. Axial CT
(C), PET (D), and fused
PET/CT (E) images show intense
activity in ninth thoracic vertebral
body (arrows), which was proven
by biopsy to be metastatic disease. Bone
metastases are very rare in malignant
peripheral nerve sheath tumor, and this
metastatic deposit was not clinically
suspected. Technetium-99m-labeled
methyldiphosphonate bone scan obtained
the day before PET showed no evidence of
disease in thoracic spine.
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Fig.
3A. —Two opposing examples of
benign nodal disease appearance on
PET/CT. In 19-year-old woman who
presented with large right popliteal
fossa mass, mass was proven by biopsy to
be embryonal rhabdomyosarcoma. Axial CT
(A), PET (B), and fused
PET/CT (C) images show absence of
FDG activity within enlarged
retroperitoneal node (arrows).
This node underwent biopsy and was found
to be negative for tumor.
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Fig.
3B. —Two opposing examples of
benign nodal disease appearance on
PET/CT. In 19-year-old woman who
presented with large right popliteal
fossa mass, mass was proven by biopsy to
be embryonal rhabdomyosarcoma. Axial CT
(A), PET (B), and fused
PET/CT (C) images show absence of
FDG activity within enlarged
retroperitoneal node (arrows).
This node underwent biopsy and was found
to be negative for tumor.
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Fig.
3C. —Two opposing examples of
benign nodal disease appearance on
PET/CT. In 19-year-old woman who
presented with large right popliteal
fossa mass, mass was proven by biopsy to
be embryonal rhabdomyosarcoma. Axial CT
(A), PET (B), and fused
PET/CT (C) images show absence of
FDG activity within enlarged
retroperitoneal node (arrows).
This node underwent biopsy and was found
to be negative for tumor.
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Fig.
3D. —Two opposing examples of
benign nodal disease appearance on
PET/CT. Same patient as described in
Figures 2A,
2B,
2C, 2D, and
2E has malignant
peripheral nerve sheath tumor. Axial CT
(D), PET (E), and fused
PET/CT (F) images show enlarged
FDG-avid left external iliac node (arrows)
that was not metastatic but contained
follicular hyperplasia and sinus
histiocytosis seen on pathologic review.
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Fig.
3E. —Two opposing examples of
benign nodal disease appearance on
PET/CT. Same patient as described in
Figures 2A,
2B,
2C, 2D, and
2E has malignant
peripheral nerve sheath tumor. Axial CT
(D), PET (E), and fused
PET/CT (F) images show enlarged
FDG-avid left external iliac node (arrows)
that was not metastatic but contained
follicular hyperplasia and sinus
histiocytosis seen on pathologic review.
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Fig.
3F. —Two opposing examples of
benign nodal disease appearance on
PET/CT. Same patient as described in
Figures 2A,
2B,
2C, 2D, and
2E has malignant
peripheral nerve sheath tumor. Axial CT
(D), PET (E), and fused
PET/CT (F) images show enlarged
FDG-avid left external iliac node (arrows)
that was not metastatic but contained
follicular hyperplasia and sinus
histiocytosis seen on pathologic review.
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Fig.
4A. —Same patient as in
Figures 1A, and
1B. Bone marrow
biopsy revealed alveolar
rhabdomyosarcoma. Axial CT (A),
PET (B), and fused PET/CT (C)
images show numerous intensely FDG-avid
metastatic deposits (arrows) in
both breasts, not appreciated at initial
physical examination.
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Fig.
4B. —Same patient as in
Figures 1A, and
1B. Bone marrow
biopsy revealed alveolar
rhabdomyosarcoma. Axial CT (A),
PET (B), and fused PET/CT (C)
images show numerous intensely FDG-avid
metastatic deposits (arrows) in
both breasts, not appreciated at initial
physical examination.
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Fig.
4C. —Same patient as in
Figures 1A, and
1B. Bone marrow
biopsy revealed alveolar
rhabdomyosarcoma. Axial CT (A),
PET (B), and fused PET/CT (C)
images show numerous intensely FDG-avid
metastatic deposits (arrows) in
both breasts, not appreciated at initial
physical examination.
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Fig.
4D. —Same patient as in
Figures 1A, and
1B. Bone marrow
biopsy revealed alveolar
rhabdomyosarcoma. Axial CT (D),
PET (E), and fused PET/CT (F)
images show presumed metastatic nodal
disease in external iliac chain on
opposite side of primary tumor (arrows).
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Fig.
4E. —Same patient as in
Figures 1A, and
1B. Bone marrow
biopsy revealed alveolar
rhabdomyosarcoma. Axial CT (D),
PET (E), and fused PET/CT (F)
images show presumed metastatic nodal
disease in external iliac chain on
opposite side of primary tumor (arrows).
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Fig.
4F. —Same patient as in
Figures 1A, and
1B. Bone marrow
biopsy revealed alveolar
rhabdomyosarcoma. Axial CT (D),
PET (E), and fused PET/CT (F)
images show presumed metastatic nodal
disease in external iliac chain on
opposite side of primary tumor (arrows).
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Fig.
4G. —Same patient as in
Figures 1A, and
1B. Bone marrow
biopsy revealed alveolar
rhabdomyosarcoma. Axial CT (G),
PET (H), and fused PET/CT (I)
images show abnormal focus of activity
in small soft-tissue nodule in left
thigh (arrows). All these sites
of abnormal activity responded to
chemotherapy and are presumed to have
been metastatic.
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Fig.
4H. —Same patient as in
Figures 1A, and
1B. Bone marrow
biopsy revealed alveolar
rhabdomyosarcoma. Axial CT (G),
PET (H), and fused PET/CT (I)
images show abnormal focus of activity
in small soft-tissue nodule in left
thigh (arrows). All these sites
of abnormal activity responded to
chemotherapy and are presumed to have
been metastatic.
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Fig.
4I. —Same patient as in
Figures 1A, and
1B. Bone marrow
biopsy revealed alveolar
rhabdomyosarcoma. Axial CT (G),
PET (H), and fused PET/CT (I)
images show abnormal focus of activity
in small soft-tissue nodule in left
thigh (arrows). All these sites
of abnormal activity responded to
chemotherapy and are presumed to have
been metastatic.
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Fig.
5A. —19-year-old man who
underwent reexcision of leiomyosarcoma
from proximal left thigh in 1999.
Follow-up MRI revealed enlarged left
external iliac nodes, so PET/CT was
performed for further evaluation.
Maximum-intensity-projection PET image
shows abnormal activity in left pelvis (arrow).
Activity in chest muscles was believed
to be physiologic in nature.
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Fig.
5B. —19-year-old man who
underwent reexcision of leiomyosarcoma
from proximal left thigh in 1999.
Follow-up MRI revealed enlarged left
external iliac nodes, so PET/CT was
performed for further evaluation. Axial
CT (B), PET (C), and fused
PET/CT (D) images localize this
activity to enlarged left external iliac
nodes (arrow). These were proven
by biopsy to be recurrent
leiomyosarcoma.
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Fig.
5C. —19-year-old man who
underwent reexcision of leiomyosarcoma
from proximal left thigh in 1999.
Follow-up MRI revealed enlarged left
external iliac nodes, so PET/CT was
performed for further evaluation. Axial
CT (B), PET (C), and fused
PET/CT (D) images localize this
activity to enlarged left external iliac
nodes (arrow). These were proven
by biopsy to be recurrent
leiomyosarcoma.
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Fig.
5D. —19-year-old man who
underwent reexcision of leiomyosarcoma
from proximal left thigh in 1999.
Follow-up MRI revealed enlarged left
external iliac nodes, so PET/CT was
performed for further evaluation. Axial
CT (B), PET (C), and fused
PET/CT (D) images localize this
activity to enlarged left external iliac
nodes (arrow). These were proven
by biopsy to be recurrent
leiomyosarcoma.
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Monitoring Response to Therapy
Evaluating response to neoadjuvant chemotherapy is
crucial in the management of childhood
sarcomas, particularly osteosarcoma, for
which tumor response is highly predictive of patient
outcome and may impact surgical planning for
amputation or limb-salvage procedures [5,
6]. Currently, the therapeutic
response of sarcomas in children is assessed
by morphologic change seen on CT and MRI.
These imaging techniques can be limited by distorted
normal anatomy, indistinct tumor border, and
a lack of reproducible quantitative
information about tumor viability [5,
6]. Radiation therapy and
chemotherapy may invoke significant changes in tumor
viability, whereas only minimal change in
morphology is apparent on conventional
imaging [6]. Brenner et al. [7]
and Hawkins et al. [8]
showed that measurement of the standard uptake value
of primary osteosarcoma, on serial FDG PET images
is an accurate indicator of tumor response to
preoperative chemotherapy. We have used
PET/CT to qualitatively monitor the response of a
variety of sarcomas to irradiation, chemotherapy,
and radiofrequency ablation (Figs.
6A, 6B,
7A, 7B,
8A, 8B,
8C, 8D,
8E, and 8F).
We have also found PET/CT to be a useful adjunct
in assessing the adequacy of surgical tumor
resection (Figs. 9A,
9B, 9C,
9D, 9E,
and 9F).
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Fig.
6A. —16-year-old boy with
large right pelvic Ewing's sarcoma,
treated preoperatively with chemotherapy
and radiation therapy.
Maximum-intensity-projection PET image,
obtained before neoadjuvant therapy,
shows intense FDG activity in primary
tumor (arrow) without evidence of
metastatic disease.
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Fig.
6B. —16-year-old boy with
large right pelvic Ewing's sarcoma,
treated preoperatively with chemotherapy
and radiation therapy.
Maximum-intensity-projection PET image,
obtained after neoadjuvant therapy,
shows minimal activity within tumor (arrow),
suggestive of good response. Pathologic
inspection of resected tumor showed less
than 5% residual viable tumor.
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Fig.
7A. —18-year-old woman with
widely metastatic alveolar
rhabdomyosarcoma who developed palpable
metastatic soft-tissue nodules on
anterior abdominal wall. PET/CT was
performed as part of metastatic
evaluation. Maximum-intensity-projection
PET image shows multiple sites of
abnormal FDG activity in chest, abdomen,
pelvis, femurs, and right humerus, which
were better localized on PET/CT than on
PET alone.
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Fig.
7B. —18-year-old woman with
widely metastatic alveolar
rhabdomyosarcoma who developed palpable
metastatic soft-tissue nodules on
anterior abdominal wall. PET/CT was
performed as part of metastatic
evaluation. Maximum-intensity-projection
PET image, obtained after bone marrow
transplantation and treatment with
chemotherapy, shows dramatic response of
all metastatic sites.
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Fig.
8A. —This 10-year-old boy had
previously undergone left pneumonectomy
for metastatic osteosarcoma when he
presented with new right pulmonary
metastases that were treated with
radiofrequency ablation. Axial CT (A),
PET (B), and fused PET/CT (C)
images obtained before radiofrequency
ablation show abnormal activity within
right upper lobe pulmonary nodule (arrows).
Biopsy of this nodule at time of
radiofrequency ablation confirmed
presence of osteosarcoma.
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Fig.
8B. —This 10-year-old boy had
previously undergone left pneumonectomy
for metastatic osteosarcoma when he
presented with new right pulmonary
metastases that were treated with
radiofrequency ablation. Axial CT (A),
PET (B), and fused PET/CT (C)
images obtained before radiofrequency
ablation show abnormal activity within
right upper lobe pulmonary nodule (arrows).
Biopsy of this nodule at time of
radiofrequency ablation confirmed
presence of osteosarcoma.
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Fig.
8C. —This 10-year-old boy had
previously undergone left pneumonectomy
for metastatic osteosarcoma when he
presented with new right pulmonary
metastases that were treated with
radiofrequency ablation. Axial CT (A),
PET (B), and fused PET/CT (C)
images obtained before radiofrequency
ablation show abnormal activity within
right upper lobe pulmonary nodule (arrows).
Biopsy of this nodule at time of
radiofrequency ablation confirmed
presence of osteosarcoma.
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Fig.
8D. —This 10-year-old boy had
previously undergone left pneumonectomy
for metastatic osteosarcoma when he
presented with new right pulmonary
metastases that were treated with
radiofrequency ablation. Axial CT (D),
PET (E), and fused PET/CT (F)
images obtained after radiofrequency
ablation show minimal activity only at
periphery of the tumor (arrows),
which may be due to inflammation or
flare phenomenon.
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Fig.
8E. —This 10-year-old boy had
previously undergone left pneumonectomy
for metastatic osteosarcoma when he
presented with new right pulmonary
metastases that were treated with
radiofrequency ablation. Axial CT (D),
PET (E), and fused PET/CT (F)
images obtained after radiofrequency
ablation show minimal activity only at
periphery of the tumor (arrows),
which may be due to inflammation or
flare phenomenon.
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Fig.
8F. —This 10-year-old boy had
previously undergone left pneumonectomy
for metastatic osteosarcoma when he
presented with new right pulmonary
metastases that were treated with
radiofrequency ablation. Axial CT (D),
PET (E), and fused PET/CT (F)
images obtained after radiofrequency
ablation show minimal activity only at
periphery of the tumor (arrows),
which may be due to inflammation or
flare phenomenon.
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Fig.
9A. —6-year-old boy who
presented with right forearm mass that
was proven by biopsy to be alveolar
rhabdomyosarcoma. Axial CT (A),
PET (B), and fused PET/CT (C)
images at baseline show intense FDG
activity within primary tumor.
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Fig.
9B. —6-year-old boy who
presented with right forearm mass that
was proven by biopsy to be alveolar
rhabdomyosarcoma. Axial CT (A),
PET (B), and fused PET/CT (C)
images at baseline show intense FDG
activity within primary tumor.
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Fig.
9C. —6-year-old boy who
presented with right forearm mass that
was proven by biopsy to be alveolar
rhabdomyosarcoma. Axial CT (A),
PET (B), and fused PET/CT (C)
images at baseline show intense FDG
activity within primary tumor.
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Fig.
9D. —6-year-old boy who
presented with right forearm mass that
was proven by biopsy to be alveolar
rhabdomyosarcoma. Axial CT (D),
PET (E), and PET/CT (F)
images obtained after surgical resection
show no evidence of residual disease in
operative bed. Surgical resection
margins were negative for tumor on
pathologic review.
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Fig.
9E. —6-year-old boy who
presented with right forearm mass that
was proven by biopsy to be alveolar
rhabdomyosarcoma. Axial CT (D),
PET (E), and PET/CT (F)
images obtained after surgical resection
show no evidence of residual disease in
operative bed. Surgical resection
margins were negative for tumor on
pathologic review.
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Fig.
9F. —6-year-old boy who
presented with right forearm mass that
was proven by biopsy to be alveolar
rhabdomyosarcoma. Axial CT (D),
PET (E), and PET/CT (F)
images obtained after surgical resection
show no evidence of residual disease in
operative bed. Surgical resection
margins were negative for tumor on
pathologic review.
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Detecting Recurrence
Children with soft-tissue and bone sarcomas are
generally followed clinically and
radiographically for 3-5 years after treatment for
evidence of tumor recurrence [5].
The likelihood of disease recurrence depends
on histologic and biologic characteristics of the tumor
and on clinical variables. Approximately 25-35% of
children and adolescents with sarcomas will
experience tumor recurrence after primary
therapy [5]. Recurrences may be
local, regional, or distant to the bones,
lungs, or other soft tissues. Follow-up
imaging currently includes MRI of the primary site (for
soft-tissue sarcomas), 99mTc MDP
bone scanning, and chest CT [5]. In
our experience, PET/CT has been useful in the
follow-up evaluation of these patients,
particularly those with alveolar rhabdomyosarcoma
because this tumor can metastasize to unusual
soft-tissue sites that may be missed by
physical examination and conventional imaging
techniques (Figs. 5A,
5B, 5C,
5D, 10A,
10B, 10C,
10D, 10E,
10F, 10G,
10H, 10I,
11A, 11B,
and 11C).
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Fig.
10A. —Same 18-year-old woman
with recurrent metastatic alveolar
rhabdomyosarcoma as seen in Figures
6A, and
6B. PET/CT,
performed as part of metastatic
evaluation, revealed many unsuspected
sites of soft-tissue metastatic disease.
Axial CT (A), PET (B), and
fused PET/CT (C) images show left
breast metastasis (arrows).
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Fig.
10B. —Same 18-year-old woman
with recurrent metastatic alveolar
rhabdomyosarcoma as seen in Figures
6A, and
6B. PET/CT,
performed as part of metastatic
evaluation, revealed many unsuspected
sites of soft-tissue metastatic disease.
Axial CT (A), PET (B), and
fused PET/CT (C) images show left
breast metastasis (arrows).
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Fig.
10C. —Same 18-year-old woman
with recurrent metastatic alveolar
rhabdomyosarcoma as seen in Figures
6A, and
6B. PET/CT,
performed as part of metastatic
evaluation, revealed many unsuspected
sites of soft-tissue metastatic disease.
Axial CT (A), PET (B), and
fused PET/CT (C) images show left
breast metastasis (arrows).
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Fig.
10D. —Same 18-year-old woman
with recurrent metastatic alveolar
rhabdomyosarcoma as seen in Figures
6A, and
6B. PET/CT,
performed as part of metastatic
evaluation, revealed many unsuspected
sites of soft-tissue metastatic disease.
Axial CT (D), PET (E), and
fused PET/CT (F) images show
abnormal FDG activity in pancreas (straight
arrows), mesenteric nodule (curved
arrows), and subcutaneous nodule (arrowheads),
all unusual sites of metastatic
rhabdomyosarcoma. Pancreatic and
mesenteric sites, shown here, were
present but overlooked on conventional
CT performed 1 week before PET/CT.
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Fig.
10E. —Same 18-year-old woman
with recurrent metastatic alveolar
rhabdomyosarcoma as seen in Figures
6A, and
6B. PET/CT,
performed as part of metastatic
evaluation, revealed many unsuspected
sites of soft-tissue metastatic disease.
Axial CT (D), PET (E), and
fused PET/CT (F) images show
abnormal FDG activity in pancreas (straight
arrows), mesenteric nodule (curved
arrows), and subcutaneous nodule (arrowheads),
all unusual sites of metastatic
rhabdomyosarcoma. Pancreatic and
mesenteric sites, shown here, were
present but overlooked on conventional
CT performed 1 week before PET/CT.
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Fig.
10F. —Same 18-year-old woman
with recurrent metastatic alveolar
rhabdomyosarcoma as seen in Figures
6A, and
6B. PET/CT,
performed as part of metastatic
evaluation, revealed many unsuspected
sites of soft-tissue metastatic disease.
Axial CT (D), PET (E), and
fused PET/CT (F) images show
abnormal FDG activity in pancreas (straight
arrows), mesenteric nodule (curved
arrows), and subcutaneous nodule (arrowheads),
all unusual sites of metastatic
rhabdomyosarcoma. Pancreatic and
mesenteric sites, shown here, were
present but overlooked on conventional
CT performed 1 week before PET/CT.
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Fig.
10G. —Same 18-year-old woman
with recurrent metastatic alveolar
rhabdomyosarcoma as seen in Figures
6A, and
6B. PET/CT,
performed as part of metastatic
evaluation, revealed many unsuspected
sites of soft-tissue metastatic disease.
Axial CT (G), PET (H), and
fused PET/CT (I) images show
additional mesenteric metastasis missed
by conventional CT (arrows).
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Fig.
10H. —Same 18-year-old woman
with recurrent metastatic alveolar
rhabdomyosarcoma as seen in Figures
6A, and
6B. PET/CT,
performed as part of metastatic
evaluation, revealed many unsuspected
sites of soft-tissue metastatic disease.
Axial CT (G), PET (H), and
fused PET/CT (I) images show
additional mesenteric metastasis missed
by conventional CT (arrows).
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Top
Abstract
Introduction