DOI:10.2214/AJR.05.0437
AJR 2006; 187:W618-W621
© American Roentgen Ray Society
18F-Choline PET/CT for Initial Staging of Advanced Prostate Cancer
Fabrice Gutman1,
Vanessa Aflalo-Hazan1,
Khaldoun Kerrou1,
Françoise Montravers1,
Dany Grahek1 and
Jean-Noël Talbot1
1 All authors: Service de Médecine Nucléaire, Hôpital Tenon,
4 rue de la Chine, Paris, France 75020.
Received March 14, 2005;
accepted after revision May 6, 2005.
Address correspondence to J.-N. Talbot
(jean-noel.talbot{at}tnn.aphp.fr).
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Keywords: cancer • PET/CT • prostate
Introduction
Among the radiopharmaceuticals for PET, carbone-11-labeled choline has been
proposed for prostate cancer imaging for a few years; more recently
18F-choline (FCH) has become available and has the potential for
widespread routine use, similar to that of 18F-FDG (FDG) in other
malignancies. In this case report we illustrate how one PET examination with
FCH performed in a clinical PET center without a local cyclotron can be at
least as informative as the sum of several modern imaging techniques.
Case Report
A 70-year-old man with prostate cancer and suspicion of bone metastases was
referred to our PET center for staging. The diagnosis of prostate cancer was
established on prostate biopsy performed because of an increased prostate
volume and high serum levels of prostate-specific antigen (PSA; 24 ng/mL). The
pathology results of endorectal prostate biopsies (six levels of biopsy)
showed a moderately to poorly differentiated (Gleason tumor grade = 8) clear
cell adenocarcinoma in all fragments but the right apices.
Because of lower back pain, the high PSA serum levels, and the poor
differentiation of the tumor, complementary radiologic and nuclear medicine
imaging techniques were performed, including bone scintigraphy, pelvic CT, and
MRI of the spine. Pelvic CT showed no capsular penetration and no tumor
extension out of the prostate bed. On the bone window, there was no detectable
lesion, particularly in the lumbar spine. The hydroxymethylene
diphosphonate-99mtechnetium (HDP-[99mTc]) bone
scintigraphy (Fig. 1A) showed a
moderate increased uptake in the lumbar spine (second and third lumbar
vertebrae), several ribs, sternum, left shoulder, and right iliac wing, with
no specific pattern of bone metastatic spread. Spine MRI, using plain T1-T2
and STIR sequences, showed a nonspecific intensity reduction of the T1 signal
and increased T2 signal on the second and third lumbar vertebrae, which are
suspicious of bone metastases in this clinical context
(Fig. 2).
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Fig. 1A —70-year-old man with prostate cancer and lower back pain who
was referred for initial staging. Hydroxymethylene
diphosphonate-99mtechnetium bone scintigraphy shows several foci of
suspicious bone metastases.
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Fig. 2 —Spine MRI of 70-year-old man with prostate cancer and lower
back pain shows homogeneous intensity reduction of T1 signal and increased T2
signal on left part of second and third lumbar vertebrae, without cortical
disruption or paravertebral invasion.
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Because of the nonspecific appearance of bone lesions at bone scintigraphy
and at MRI of the spine, this patient underwent, in our PET center, both FDG-
and FCH-PET on a hybrid PET/CT machine (Gemini, Philips Medical Systems). The
patient gave written informed consent to undergo PET with FCH.
The patient fasted 6 hours before FDG injection and his serum glucose level
was 6.1 mmol/L. FDG-PET/CT images were acquired 1 hour after injection of 4
MBq/kg of FDG. Helical CT was acquired at the beginning of the PET/CT
examination, with the following parameters: 40 mAs, 140 kV, and 5-mm section
thickness. CT images were used for attenuation correction and fusion; no
iodine contrast media were administered. Whole-body CT was performed in a
craniocaudal direction. PET images were subsequently acquired with 12 bed
positions of 3 minutes each, from the skull to the mid thigh. FDG-PET/CT
(Fig. 1B) showed bone focal
uptakes located in the spine (T2, T3, T12, L2, and L3) and iliac wings. No
abnormal FDG uptake was seen in the prostate bed
(Fig. 3A) or in the pelvic
area.
FCH-PET/CT images were acquired 15 minutes after injection of 2 MBq/kg of
FCH (Iasocholine, Iason), with the same protocol as that for FDG-PET/CT.
Physiologic uptake in the salivary glands, lungs, liver, kidneys, pancreas,
and pituitary gland was seen. FCH-PET/CT
(Fig. 1C) showed an increased
prostate uptake, particularly in the right lobe, with at least three foci of
increased uptake (standardized uptake value-maximum [SUVmax] = 4.9)
(Fig. 3C). FCH-PET/CT also
showed intense abnormal foci of bone uptake on skull, spine (C3, C4, T2, T3,
T5, T12, L2, L3), ribs, ilium, and right shoulder images. Foci of bone uptake
on FCH-PET/CT images were much more intense and extensive than on FDG-PET/CT
(SUVmax = 7.7 vs 5.5) (Figs.
4A,
4B, and
4C). In most cases, the bone
metastases discovered on FCH-PET were matched with abnormal bone sclerotic
lesions on corresponding CT slices, whereas the previous diagnostic CT with
injection of contrast media was considered negative.
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Fig. 3C —Transaxial slice of prostate gland of 70-year-old man with
prostate cancer and lower back pain. 18F-choline PET image shows
three foci of increased uptake on right lobe of prostate (arrow),
which correspond to primary tumor.
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Fig. 4A —Bone metastases in 70-year-old man with prostate cancer and
lower back pain. CT slices. In most cases, bone foci seen with FCH-PET match
abnormal bone sclerotic lesions seen on corresponding CT slices
(arrow on L3).
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Discussion
Primary staging of prostate cancer is important for patient management,
particularly in the most aggressive locally advanced tumors. Both the clinical
stage of the disease and the probability of nonlocalized disease determine the
choice of therapy. Lymph node metastases are found at the initial diagnosis in
up to 25% of patients with prostate cancer, depending on the tumor stage and
grade [1]. No consensus,
however, exists on the strategy of diagnostic tests for pretreatment
evaluation. Endorectal sonography, CT, MRI, and bone scintigraphy are
routinely used to define the extent of advanced disease. CT and MRI have low
sensitivity for detection of lymph node metastases and adjacent soft-tissue
involvement in patients whose lymph nodes are smaller than 10-15 mm
[2]. For these patients, MRI
with lymphotropic superparamagnetic nanoparticles is a promising technique for
accurately diagnosing lymph node metastases
[3]. Bone scintigraphy has a
limited specificity.
FDG-PET is well documented in the imaging workup of various malignancies.
FDG-PET is now recognized as a useful tool for the initial staging before
surgery of several cancers, such as lung cancer, esophageal cancer, head and
neck cancers, and locally advanced breast cancer. Yet, the limitations of
FDG-PET are apparent in slow-growing tumors such as prostate carcinomas,
because of their modest enhancement of glycolysis. Many primary prostate
cancers show either relatively low FDG uptake
[4] or no visible uptake, as in
the present patient. This is also true for nodal and bone metastases. Yeh et
al. [5] reported a low
detection rate of 16% for detecting bone lesions with FDG-PET in prostate
cancer compared with bone scintigraphy. This limited sensitivity for the
staging of advanced prostate cancer with FDG-PET motivated efforts to develop
new oncologic tracers for PET. Because tumor cells are also characterized by
their ability to actively incorporate choline to produce phosphatidylcholine
(a membrane constituent) to facilitate tumor cell duplication, several authors
compared 11C-choline to FDG for diagnosis and staging of prostate carcinoma.
Previous studies comparing 11C-choline to FDG in prostate cancers showed that
11C-choline has a better sensitivity for detecting metastases. The efficacy of
radiolabeled 11C-choline for localizing primary or metastatic prostate cancer
has been studied in more than 250 patients
[1,
6-8].
However, the use of 11C-choline is limited only to PET centers that have
onsite cyclotrons because of its short half-life (approximately 20 minutes).
This drawback prompted the development of FCH, a radiopharmaceutical with a
half-life of 110 minutes, for imaging prostate cancer and associated lymph
node involvement [9]. FCH is
more easily available in clinical PET centers and provides higher resolution
images as a result of its shorter positron length path. FCH has greater
urinary excretion than 11C-choline, but routinely performed dynamic pelvic
acquisition overcomes this drawback as pathologic uptake begins 1 minute
postinjection, before urinary excretion and bladder filling.
It is likely that FCH-PET/CT will be useful as an accurate and noninvasive
staging tool, at least in selected groups of patients with high suspicion of
regional or metastatic disease—prebiopsy serum PSA levels greater than
20 ng/mL, poorly differentiated tumors at needle biopsy (Gleasons tumor grades
8-10), or palpable locally advanced tumors.
Acknowledgments
We thank Victor Izrael, Department of Oncology, Hôpital Tenon, for
referring the patient to our center.
References
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Introduction
Case Report
