Joint Program in Nuclear Medicine
Prostascint (Indium-111 Labeled Capromab Pendetide) Imaging
Christopher P. Fey, MD
Annick D. Van den Abbeele, MD
October 6, 1998
Presentation
73-year-old male with prostate cancer and questionable lymph node on CT.
Bone scan was negative. For staging.
Imaging Technique
96 hours after injection with In-111-labeled Prostascint, planar and SPECT
images were obtained. At this time, a blood pool scan was also performed,
using Tc-99m-labeled RBCs and dual acquisition was obtained.
Imaging Findings
-
fig
1 - axial CT shows questionable node near aortic bifurcation.
-
fig 2 - planar Prostascint and RBC images
show no activity in the region of the node.
-
fig 3 - posterior Prostascint images
show a focus of uptake in the LUQ - RBC images show this finding has intense
blood pool activity.
-
fig 4 - axial CT shows this finding to be
a splenule.
-
fig 5 - axial SPECT images show blood
pool activity in the femoral vessels and penile base - Prostascint uptake
is seen in the prostate
Differential Diagnosis
Prostascint's physiologic distribution is that of a whole murine antibody.
Uptake is seen in prostate metastases, primary prostate neoplasms, and
normal prostate tissue. Prostascint shows blood pool activity as well as
bowel activity.
Diagnosis
No evidence of extraprostatic tumor on this scan.
Discussion
The Antibody Prostascint is a whole murine monoclonal antibody which is
directed against prostate membrane specific antigen (PMSA), a transmembrane
glycoprotein expressed by prostate epithelial cells. PMSA expression is
higher in prostate adenocarcinoma cells than in nonmalignant cells, and
it is higher in metastatic lesions than in primary lesions.
Indications Prostascint may be useful to evaluate postprostatectomy
patients with rising PSA who have an otherwise negative or equivocal workup
for metastases. Another potential role for Prostascint (controversial)
is in the staging of newly diagnosed prostate cancer.
Pearls -Tomographic (SPECT) acquisitions are essential -Prostascint
studies should be interpreted with the aid of a CT scan. -Use dual acquisition
with Tc-99m labeled RBC blood pool images to distinguish blood pool structures.
-Use delayed views to help clarify activity within the bowel if necessary.
References
Kahn et al., “111-Indium Capromab Pendetide in the Evaluation of Patients
with Residual or Recurrent Prostate Cancer after Radical Prostatectomy,”
J Urol (1998 Jun) 159(6):2041-6.
Lamb et al., “Capromab Pendetide: A Review of Its Use as an Imaging
Agent in Prostate Cancer,” Drugs Aging (1998 April) 12(4):293-304.
Kahn et al., “Radioimmunoscintigraphy with In-111-labeled Capromab Pendetide
Predicts Prostate Cancer Response to Salvage Radiotherapy after Failed
Radical Prostatectomy,” Journal of Clinical Oncology, vol 16, no 1, (Jan)
1998 pp. 284-289.
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J. Anthony Parker, MD PhD, Tony_Parker@bidmc.harvard.edu
