non-pet tumor imaging p3_thallium
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Jiraporn Sriprapaporn, M.D.
Nuclear Medicine
Siriraj Hospital
Mahidol University September 2015
Non-PET Oncologic Imaging_Jiraporn
Radiopharmaceuticals for Non-PET Oncologic Applications
Nonspecific
• Ga-67 citrate:
– Lymphoma
• Tl-201 chloride:
– Bone sarcomas
– Brain tumors
– Thyroid cancer
• Tc-99m sestamibi:
– Breast cancer
– Parathyroid adenomas
– Thyroid cancer
• Tc-99m tetrofosmin: Similar to sestamibi
Tumor-Type Specific
• I-131: Diff thyroid cancer (PTC, FTC)
• I-131 MIBG: Neural crest tumors (adrenal medullary imaging)
• Radiolabeled peptides: Somatostatin receptors (SSTR)
– In-111 pentetreotide (OctreoScan): Neuroendocrine tumors [NETs]
– Tc-99m HYNIC-TOC: NETs
– Tc-99m depreotide*: Lung cancer
• Radiolabeled monoclonal antibodies:
– Tc-99m arcitumomab (CEA-Scan)*: Colorectal cancer
– In-111 capromab pendetide (ProstaScint): Prostate cancer
– In-111 ibritumomab tiuxetan (Zevalin): Lymphoma
– I-131 tositumomab (Bexxar): Lymphoma
REF : modified from The Requisites
Non-PET Oncologic Imaging_Jiraporn
Physical Characteristics of Common Radionuclides Used for Tumor Imaging Agents
Radiotracer Physical T1/2 (hr)
Decay
Photopeaks
Injected dose mCi (MBq)
Organ receiving
highest dose rad/ mCi
(mGy/MBq)
Effective dose
rem/mCi (mSv/MBq)
keV Abundance
(%)
Ga-67* 78 EC
93 185 300 394
41 23 18 4
10 (370) Colon
0.74 (0.2) 0.44 (0.12)
Tl-201* 73 EC 69-83 94 3 (111) Kidneys
1.7 (0.46) 0.85 (0.23)
In-111* 67 EC 171 245
90 94
6 (222) Spleen
2.1 (0.57) 0.20 (0.054)
Tc-99m sestamibi
6 IT 140 88 20 (740) Gallbladder 0.14 (0.039)
0.033 (0.009)
modified from The Requisites, 4th Ed. SNM Guidelines
* Cyclotron-produced
Non-PET Oncologic Imaging_Jiraporn
• Tl-201 is cyclotron produced.
• Nonspecific tumor imaging
• Mechanism:
– Tl-201 behaves as a potassium analog
– Transmembrane electropotential gradient
– Na-K ATPase system
– Uptake also depends on cell type, viability, & regional
blood flow
• Excretion: Kidneys* (critical organ)
• Dose: 3-5 mCi IV.
• Scan time at 10-20 min. pi.+/- delayed 3 hrs
Non-PET Oncologic Imaging_Jiraporn
• Choroid plexus of the lateral ventricles,
• Salivary glands,
• Thyroid,
• Myocardium,
• Liver, spleen, splanchnic areas,
• Kidneys, bladder, and testes.
• Skeletal muscles,
• No bone marrow activity (if not marrow hyperplasia)
• The elimination of thallium is slow, with a Tbio of 10 days.
• Excretion: via kidneys Bladder is the critical organ. Anterior Posterior
Non-PET Oncologic Imaging_Jiraporn
False-positive Tl-201
• Benign bone tumors
• Stress fractures
• Inflammation
• Healing surgical wound
• Tuberculosis
TB: Abnormal Tl-201 retention at he mediastinum. (solid arrow), para-aortic region and left inguinal area (dashed arrow). Amukotuwa S, et al. International Seminars in Surgical Oncology. 2005;2:10 doi:10.1186/1477-7800-2-10
Non-PET Oncologic Imaging_Jiraporn
False-negative Tl-201
• Type of tumors-low or nonavid
• Small lesions
• Location of the lesion
– Close high-activity physiologic uptake area
– Deep lesions highly attenuated area (planar
images)
Non-PET Oncologic Imaging_Jiraporn
• Differentiate benign from malignant diseases
• Determine grade of malignancy
• Localize site for biopsy
• Evaluate the tumor response
• Differentiate post-therapy tissue necrosis or
fibrosis from residual tumor &/or local
recurrence
Non-PET Oncologic Imaging_Jiraporn
Tl-201 Clinical Applications
• Brain tumors
• Bronchogenic carcinoma
• Thyroid carcinoma
• Parathyroid adenoma
• Bone & soft tissue sarcoma
• Breast cancer
• Lymphoma :
– Low-grade Tl > Ga uptake
– High-grade Ga > Tl uptake*
• Head & neck cancers
Kaposi sarcoma is mesenchymal tumor that involves the lymphovascular system.
Non-PET Oncologic Imaging_Jiraporn
• Shorter waiting time for imaging
• Tl-201 is more specific than Ga-67 to
differentiate tumors from acute inflammatory
lesions ( thallium generally shows less uptake
in benign tumors, inflammatory processes,
and remodeling bone.)
• The intracellular uptake of Tl-201 is not
affected by steroid adm., chemotherapy, or
radiation therapy.
Essentials NM AuntMinnie.com
Non-PET Oncologic Imaging_Jiraporn
Drawbacks of Tl-201 Scan
• Limited availability & high cost since Tl-201 is
cyclotron-produced and needed to be imported.
• Low dose of Tl-201 is used due to high radiation
exposure (long physical T1/2 of 73 hrs).
• Physical properties of Tl-201 is suboptimal for
imaging.
Non-PET Oncologic Imaging_Jiraporn
Clinical Applications: Brain Neoplasms
• Thallium accumulates in malignant gliomas in proportion
to the aggressiveness of the lesions.
• Low-grade lesions concentrate little or no thallium,
whereas high-grade gliomas show markedly increased
activity.
• Gliosis surrounding brain abscesses, however, may also
demonstrate marked thallium accumulation.
correlation with CT or MRI and clinical findings.
Non-PET Oncologic Imaging_Jiraporn
Tl-201 SPECT & Low-grade Glioma
• A 37 year-old female with low-
grade glioma, s/p ERT followed by
resection and now with recent MRI
that shows enhancement near the
vertex on the right.
Non-PET Oncologic Imaging_Jiraporn
Brain Tumor at Hypothalamous
Tc-99m MDP Tl-201
Non-PET Oncologic Imaging_Jiraporn
AIDS-related Neoplasm
• Kaposi sarcoma (KS) is a low to intermediate grade
mesenchymal tumor that involves the lymphovascular
system.
• The tumor can have multi organ involvement inclusive of
pulmonary, gastrointestinal, cutaneous and
musculoskeletal systems.
• DDx Kaposi sarcoma vs lymphoma
– Kaposi sarcoma is thallium avid but does not take up gallium,
– Lymphoma concentrates both agents.
Kaposi sarcoma Tl+ve, Ga-ve
Lymphoma Tl+ve, Ga+ve
Non-PET Oncologic Imaging_Jiraporn
Kaposi Sarcoma of the Lung
• Thallium-positive and a gallium-
negative lesion in the lungs.
• CXR: bilateral pulmonary infiltrate
(A).
• Planar Tl-201 images: early (B),
delayed (C) and early SPECT (D)
and delayed
• SPECT (E).
• Ga-67 scan: Planar total body Ga-
67 scan (F) and Ga-67 SPECT
(G) showing NO increased uptake
in both lungs.
• Incidentally, there is a small focal
uptake in left SPC region without
corresponding thallium uptake
which is most likely due to acute
inflammatory pathology.
Abdel-Dayem HM 1996
Non-PET Oncologic Imaging_Jiraporn
Kaposi Sarcoma: References
1. Abdel-Dayem HM, Bag R, DiFabrizio L, Aras T, Turoglu HT, Kempf
JS, Habbab N, Pescatore F, Sadik A, Kowalsky W. Evaluation of
sequential thallium and gallium scans of the chest in AIDS patients.
J Nucl Med. 1996 Oct;37(10):1662-7. PMID: 8862304.
2. Lee VW, Fuller JD, O'Brien MJ, Parker DR, Cooley TP, Liebman
HA. Pulmonary Kaposi sarcoma in patients with AIDS: scintigraphic
diagnosis with sequential thallium and gallium scanning. Radiology.
1991 Aug;180(2):409-12. PMID: 2068302.
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