Nuclear Medicine Michael R. Lewis, Ph.D. Associate Professor Department of Veterinary Medicine & Surgery Department of Radiology Nuclear Science & Engineering Institute

Fisson/Reactor Products Cyclotron Products Generally decay by b- emission because of excess neutrons Not many are useful for diagnostic imaging, but several are useful for radiotherapy Generally decay by b+ emission or electron capture because of excess protons Many are useful for diagnostic imaging (gamma scintigraphy or positron emission tomography)

Definition of Radiopharmaceutical Radioactive compound used for diagnosis and/or therapy of diseases In nuclear medicine, ~95% of radiopharmaceuticals used for diagnosis, while the rest are used for therapy Radiopharmaceuticals have no pharmacologic effect, since they are used in tracer quantities

Ideal Radiopharmaceutical for Imaging - Factors to Consider Administering to patients What is the radiation dose to normal organs? Radiochemical and radionuclidic purity must be extremely high Regulatory approval required for human use Scope and limitations of instrumentation Gamma scintigraphy vs. single photon emission computed tomography (SPECT) vs. positron emission tomography (PET)

Ideal Physical Characteristics of Imaging Radiopharmaceutical Decay Mode gamma (gamma scintigraphy) or positron (PET) a and b- emitters avoided if at all possible; cause higher absorbed dose to organs and tissues “Good” Energy emissions of radionuclide Easily collimated and shielded (lower dose to personnel) easily detected using NaI crystals (e.g. Tc-99m decays by 140 keV photons which is ideal) low radiation dose to the patient (no a or b)

Ideal Physical Characteristics of Imaging Radiopharmaceutical Ideal half-life long enough to formulate RaPh and accomplish imaging study short enough to reduce overall radiation dose to the patient physical half-life of radionuclide should be matched well to biological half-life of RaPh Readily Available geographic distance between user and supplier limits availability of short-lived radionuclides/RaPh Generator-produced radionuclides are desirable

Ideal Biological Characteristics of Radiopharmaceutical Ideal biological half-life long enough to complete the procedure (i.e. localize to target tissue while minimizing background) short enough to reduce overall radiation dose to the patient High target:non-target ratio rapid blood clearance rapid localization in target tissue rapid clearance from non-target tissues (liver, kidney, intestines)

Radioactive Decay Processes 1. alpha ++ 2. beta minus - 3. beta plus + 4. e- capture EC 5. isomeric transition  6. Internal conversion IC

Diagnostic Nuclear Medicine

Anatomic vs. Physiologic Imaging

How does Physiologic Imaging Work? Anatomy vs. Function in a broken leg

Anatomy vs. Physiology

Gamma Camera device most commonly used to obtain an image in nuclear medicine sometimes called a scintillation camera or Anger camera camera obtains an image of the distribution of a RaPh in the body (or organ) by detection of emitted g-rays

Gamma Camera Consists of… A collimator sodium iodide crystal (detector) photomultiplier (PM) tube array position circuit summation circuit pulse height analyzer

Sodium Iodide Detector Gamma rays which interact in the crystal will deposit energy in the crystal to produce “fast electrons” with high kinetic energy Mechanisms of interaction are: Photoelectric effect Compton scatter Pair production (not relevant to NM)

Sodium Iodide Detector, cont’d... As electrons slow down in crystal their KE is converted, in part, into light scintillations A relatively constant proportion of the light scintillations (produced by each g-ray) will exit the crystal and hit the photocathode of the photomultiplier tube The crystals used in gamma cameras are typically 40-60 cm in diameter and 1 cm thick

Collimator The purpose of the collimator is to define a field of view each very small area of the detector ‘sees’ only a small part of the organ to be imaged two basic types of collimators: multi-hole (4000-10000 holes) (used more in modern gamma cameras) single or pin-hole

Gamma Camera Basics* *JPNM Physics website

GE Whole Body Gamma Camera

SPECT Imaging

Mo-99/Tc-99m Generator Column Chromatography When saline is passed over column, the 99mTcO4- is dissolved and less strongly adsorbed to alumina.

Cardiac Infarction 201TlCl Rest 99mTc-Sestamibi Stress Test

Cardiac Ischemia 201TlCl Rest 99mTc-Sestamibi Stress Test

(MDP) (EDP) (HDP)

Normal Canine Bone Scan 99mTc-MDP (Methylene Diphosphonate)

Rib Metastasis

Juvenile Osteosarcoma 11-year old boy with a one month history of right knee pain Increase activity in the right tibia Diagnosis: Osteosarcoma

Metastatic Prostate Carcinoma Imaging 99mTc-HDP

Principle of PET Imaging Each annihilation produces two 511 keV photons traveling in opposite directions (180O) which are detected by the detectors surrounding the subject

Fluorodeoxyglucose Metabolism PLASMA TISSUE G L U T FDG

[18F]Fluorodeoxyglucose (FDG)

Brain Metabolism ([18F]FDG) PET Brain Metabolism ([18F]FDG) Control Alzheimer’s Disease Center for Functional Imaging; Life Sciences Division; Lawrence Berkeley National Laboratory; Berkeley, CA.

Normal Cocaine Abuser [11C]Raclopride PET Brain Study nCi/cc 1000 800 600 Cocaine Abuser 400 200 Courtesy BNL PET Project

Therapeutic Nuclear Medicine

Fission products useful in nuclear medicine include: Mo-99 Fission products useful in nuclear medicine include: 99Mo, 131I, 133Xe, 137Cs and 90Sr

Differentiated Thyroid Carcinoma 5 mCi Na131I Imaging Treatment Planning 48 h p.i.

Differentiated Thyroid Carcinoma Therapy 105 mCi Na131I 27 h p.i.

Differentiated Thyroid Carcinoma Post Surgical Resection Therapy 57Co Flood Source + 105 mCi Na131I

Differentiated Thyroid Carcinoma 201TlCl and 99mTc-Sestamibi Imaging 4 months after Na131I Therapy

Canine Osteosarcoma Tumor distal radius

Story of QuadraMetTM -- I 153Sm identified as a useful nuclide for radiotherapy by MU researchers Development began in early 1980’s at MU in collaboration with the Dow Chemical Company [phosphonate ligand complexes;153Sm-EDTMP] Successful in treatment of primary osteosarcoma in canine patients, with added bonus of 18% cure rate [MU College of Veterinary Medicine]

One of Our First Patients

Bone Scans of Canine Patient -Veterinary nuclear medicine imaging facilities at MU allowed us to diagnose and monitor the bone cancer in patient dogs Before Treatment: 8/15/85 After Treatment: 3/3/86

Results of Clinical Trial of 153Sm-EDTMP in Canine Osteosarcoma Response # of Dogs (%) Survival (months) Disease Free 7 (18%) 11 - 60 Partial Response 25 (62%) 1 - 16 No Response 8 (20%) 0.5 - 1 -First documented cures of dogs with bone cancer, without amputation, reported in the literature.

Story of QuadraMet™ -- II Clinical trials began in late 1980’s, with doses supplied by MURR for Phase I studies ~80% efficacy, with ~25% obtaining full pain remission Approved in U.S. for pain palliation of metastatic bone cancer in March, 1997

153Sm-EDTMP [QuadraMet] + 153Sm 99mTc-MDP 153Sm-EDTMP N PO H 3 2 The development Quadramet exemplifies the translational research capabilities at MU: from the and production of the radioisotope (Sm-153) and the identification of the phosphonate comppound, (EDTMP) which targets bone cancer to the initial clinical trials in human patients.

Experimental Nuclear Medicine

Radiopharmaceutical Design The design of an effective tumor-targeting radio-pharmaceutical involves appropriate selection of: Targeting vector (e.g., mAb, peptide hormone, small molecule, etc.) Radionuclide (e.g., diagnostic – 99mTc, 111In, etc.; therapeutic – 188Re, 90Y, 177Lu, etc.) Bifunctional chelating agent (BCA) Linker or spacer Targeting Vector Linker Bifunctional Chelating Agent M Radiometal

Hypothesis 1 Non-invasive imaging of bcl-2 mRNA expression in lymphoma may aid in the identification of chemotherapy patient risk groups, who might respond better to targeted immunotherapy, radioimmunotherapy, or antisense therapy.

Receptor Targeting for Molecular Imaging and Therapy Radiometal chelation should be stable under physiological conditions. Chelate modification should not lower the receptor binding affinity.

Internalizing vs. Non-internalizing Receptors Bryan JN, et al. Vet. Comp. Oncol. 2004; 2:82-90 Courtesy of Derek B. Fox, D.V.M., Ph.D.

Peptide Nucleic Acid

Cellular Delivery of PNA Chelator PNA Peptide

* DOTA-Tyr3-Octreotate N O H D P h e C y s T r p L S * M *M = 111In for gamma scintigraphy and single photon emission tomography (SPECT), 64Cu for positron emission tomography (PET), or 177Lu for targeted radiotherapy (TRT).

PNA and Peptide Conjugates

MicroSPECT/CT Using 111In-labeled PNA and Peptide Conjugates (1 h, 48 h) Antisense Nonsense Ala TATE Consistent with the biodistribution study that kidneys were the primary organ of accumulation of the PNA conjugates. Jia F, et al. J. Nucl. Med. 2008; 49: 430-438

Bcl-2 mRNA Expression Levels in Mec-1 and Ramos Cells 3821 1 (Bcl-2 +) (Bcl-2 -)

MicroSPECT/CT Using 111In-DOTA-anti-bcl-2-PNA-Tyr3-octreotate (48 h) Mec-1 Ramos

MicroPET/CT Using 64Cu-DOTA-anti-bcl-2-PNA-Tyr3-octreotate Mec-1 Ramos 1 h 3 h 24 h 48 h

Hypothesis 2 Dogs with naturally occurring B-cell lymphoma will demonstrate tumor specific uptake of 111In-anti-bcl-2-PNA- Tyr3-octreotate that correlates negatively with response to chemotherapy.

111In-DOTA-Tyr3-Octreotate Scintigraphy Nodes 1 h post-injection 4 h post-injection 24 h post-injection

PNA Imaging of Normal Dog This is an scintigraphy scan of a normal healthy patient. There appears to be no specific imaging agent uptake.

Partial Remission Initial Scan Remission Scan

Complete Remission Initial Scan Remission Scan Relapse Scan

Hypothesis 3 Combined radionuclide and antisense therapy may act synergistically or additively with respect to cell proliferation and viability in an in vitro model of B-cell lymphoma.

Western Blot Analysis Tubulin bcl-2 1 2 3 4 5 1 2 3 4 5 1. Cells without treatment 2. Cells treated with 2 μg of DOTA-anti-bcl-2-PNA-Tyr3-octreotate for 48 h 3. Cells without treatment 4. Cells treated with 2 μg of DOTA-nonsense-PNA-Tyr3-octreotate for 48h 5. Cells treated with 2 μg of DOTA-anti-bcl-2-PNA-Ala for 48 h Analysis of protein inhibition. Quantitive analysis showed 51.0% of bcl-2 protein inhibition by the treatment of 2 ug of DOTA-anti-bcl-2-PNA-Tyr3-Octreotate

Cell Viability Assay Day 2 p<0.002 Day 3 p<0.005 The viability curve shows a general decrease through out the study however days two and three demonstrate statistically significant mass effects p=0.005 and p=0.002 respectively further at day3 these levels are well below those found for Lu-DOTA-TATE 70

TUNEL Assays IMR-32 SH-SY5Y Anti-bcl-2 + Anti-FLIP Anti-bcl-2 + CH11 Anti-bcl-2 Anti-FLIP + CH11 SH-SY5Y IMR-32

Acknowledgments Dr. Carolyn Anderson Washington University Dr. Henry VanBrocklin Lawrence Berkeley Lab Dr. Joanna Fowler Brookhaven National Lab Dr. Gregory Daniel University of Tennessee Dr. Alan Ketring University of Missouri Dr. Wynn Volkert University of Missouri