Translate this page into:
Metastatic superscan in prostate carcinoma on gallium-68-prostate-specific membrane antigen positron emission tomography/computed tomography scan
Address for correspondence: Dr. Madhavi Tripathi, Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi - 110 029, India. E-mail: madhu_deven@yahoo.com
This is an open access article distributed under the terms of the Creative Commons Attribution NonCommercial ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non commercially, as long as the author is credited and the new creations are licensed under the identical terms.
This article was originally published by Medknow Publications & Media Pvt Ltd and was migrated to Scientific Scholar after the change of Publisher.
Abstract
We describe the imaging features of a metastatic superscan on gallium-68 Glu-NH-CO-NH-Lys-(Ahx)-[Ga-68(HBED-CC)], abbreviated as gallium-68-prostate-specific membrane antigen (68Ga-PSMA) positron emission tomography/computed tomography (PET/CT) imaging. 68Ga-PSMA is novel radiotracer undergoing evaluation for PET/CT imaging of prostate carcinoma. This patient had a superscan of metastases on conventional bone scintigraphy and was referred for 68Ga-PSMA PET/CT to evaluate the feasibility of 177Lu-PSMA therapy.
Keywords
Gallium-68-prostate-specific membrane antigen
metastasis
positron emission tomography/computed tomography
prostate carcinoma
A 55-year-old case of metastatic prostatic adenocarcinoma on docetaxel chemotherapy, with rising serum prostate-specific antigen (sPSA) level, underwent bone scintigraphy. Gleason score was 9 (5 + 4), and sPSA level was 340 ng/mL. Findings on bone scintigraphy showed diffusely increased skeletal accumulation with increased bone-to-soft tissue (renal uptake) ratio suggestive of a metastatic superscan [Figure 1a - anterior and b - posterior view]. He further underwent gallium-68-prostate-specific membrane antigen (68Ga-PSMA) PET/CT to evaluate feasibility for 177Lu-PSMA therapy. Maximum intensity projection image [Figure 2a] showed generalized increased tracer uptake in entire axial and appendicular skeleton with reduced physiological uptake in bilateral lacrimal and salivary glands, spleen, small bowel, and kidneys. Sagittal [Figure 2b] and transaxial positron emission tomography/computed tomography (PET/CT) fusion images [Figure 2c–e] showed sclerotic changes in the entire axial skeleton with increased tracer uptake. All features were suggestive of metastatic superscan on 68Ga-PSMA PET/CT.
Superscan is a well-known phenomenon on bone scintigraphy characterized by increased bone-to-soft tissue ratio with a symmetrical increased skeletal uptake and reduced tracer uptake in nonaffected bones and soft tissue.[1] Common conditions include metastatic cancers and metabolic bone disease that give rise to this appearance on skeletal scintigraphy.[2] This phenomenon has also been described previously in the literature on 18F-fluorodeoxyglucose PET/CT and 68Ga-labeled [1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid]-1-NaI3-octreotide PET/CT scan where a superscan implies a high contrast between metastatic and nonmetastatic organs.[3456] In this case, there was increased tracer accumulation in entire axial and appendicular skeleton and reduced tracer uptake in the salivary and lacrimal glands, spleen, proximal small gut, and kidneys which normally show the physiological distribution of 68Ga-PSMA. This case demonstrates the altered biodistribution pattern in a metastatic superscan of 68Ga-PSMA PET/CT, which further predicts a poor prognosis.[78]
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest
REFERENCES
- Absent or faint renal uptake on bone scan. Etiology and significance in metastatic bone disease. Clin Nucl Med. 1991;16:545-9.
- [Google Scholar]
- Nuclear medicine studies in metabolic bone disease. Semin Musculoskelet Radiol. 2002;6:323-29.
- [Google Scholar]
- Bone metastasis versus bone marrow metastasis. Integration of diagnosis by (18) F-fluorodeoxyglucose positron emission/computed tomography in advanced malignancy with super bone scan: Two case reports and literature review. Kaohsiung J Med Sci. 2013;29:229-33.
- [Google Scholar]
- Metastatic neuroendocrine carcinoma presenting as a “Superscan” on 68Ga-DOTANOC somatostatin receptor PET/CT. Clin Nucl Med. 2012;37:892-4.
- [Google Scholar]
- Heterogeneity of prostate-specific membrane antigen (PSMA) expression in prostate carcinoma with distant metastasis. Pathol Oncol Res. 2009;15:167-72.
- [Google Scholar]
- Metastatic Prostate Carcinoma Presenting as a Superscan on 68Ga-PSMA PET/CT. Clin Nucl Med. 2015;40:755-6.
- [Google Scholar]