– The clinical utility of ultrafast cardiocentric 3D SPECT novel semi-conductor scanner technology – Berry Allen PhD 31 August 2013

Nuclear Medicine (Molecular Imaging) Principles Functional clinical information derived from observing radiopharmaceutical distribution / kinetics at a molecular level. Diagnostic data is provided by observing the pharmaceutical kinetics In vivo studies undertaken on a Gamma Camera / PET scanner. Radionuclide is ‘passive’; enabling the pharmaceutical to be localised. 99mTechnetium is the most frequently used radioisotope 140 kev γ photon 6.02 hour physical half-life

Gamma Camera Principles The gamma camera detector consists of: - collimator - scintillation crystal (Tl NaI) - an array of photomultiplier tubes - electronic system for detection and measurement of gamma energies The emission of a single gamma ray is a very small scale nuclear phenomenon It is the role of the gamma camera detector to amplify this photon into an electric signal that can be detected By exploiting a large number of detected photons and resulting electric signals, it is possible to map the radioactive nuclei responsible for the emission of gamma rays

Conventional (Gamma) camera configuration

Semi conductor (CZT) detectors Cadmium Zinc Telluride (Cd ZnTe), is a semiconductor material that directly converts X-rays or Gamma-rays to electrons 15 -20 times increase in count rate sensitivity compared to NaI – shorter imaging times Capable of processing more than one million photons per second per square mm Spectroscopic resolution of CZT outperforms most other detectors True 3D volumetric acquisition No reconstruction resolution recovery or collimator recovery algorithms / processing required 530c - 4.6 mm spatial resolution (pin hole collimation) 5% – 6% Energy resolution (NaI crystal ~ 11 - 13%)

Stationary semi conductor Cardiac scanners D-SPECT scanner

Garcia et al JNM Vol. 52 • No. 2 • February 2011 GE D530c Stationary Data (Gantry) Acquisition Single Photon Emission Computed Tomography SPECT camera design with standard parallel hole collimators is more than 50 years old ‘Conventional’ SPECT - inefficient as only small part of the available crystal area is used to image the heart (Fig A) Novel dedicated scanner - all available detectors are constrained to imaging just the cardiac field of view (Fig B) Garcia et al JNM Vol. 52 • No. 2 • February 2011

Garcia et al JNM Vol. 52 • No. 2 • February 2011 GE D530c Stationary Data (Gantry) Acquisition Indirect radiation conversion with conventional SPECT detector (Fig A) Direct radiation conversion with CZT detector (Fig B) Garcia et al JNM Vol. 52 • No. 2 • February 2011

Module / Detector/ Triplet Assembly 1 Triplet with 3 Detectors 1 CZT Module 4 Modules in a Detector

D530c Stationary Data Gantry Acquisition Consisting of an array of 19 pinhole collimators,each with 4 solid-state CZT pixilated modules All 19 detectors simultaneously image the heart Nine of the pinhole detectors are oriented perpendicular to the patient’s long axis and 5 are angulated above and 5 below the axis for a true 3-dimensional acquisition geometry

Pathophysiology of Coronary Artery Disease

Pathophysiology of Coronary Artery Disease

530c CZT / NaI Comparison 99mTc based tracer 530 CZT ‘Standard’ NaI 530c CZT / NaI Comparison 99mTc based tracer 530 CZT Patient: 67 yr female weight: 50 kg Indication: Atypical chest pain Presurgical assessment Procedure: Low dose stress (pharmacologic) 6 min scan NaI 20 min scan

Dual energy 201Thallium – 99mTc cardiac imaging The ‘Ideal‘ option This technique is not possible on standard gamma camera due to poor photon energies separation characteristics ~ 65% injected radioactivity dose reduction The procedure is now a LOW dose study. Was a HIGH dose procedure Immediate imaging 60% reduction in imaging time relative to standard gamma camera 1 hour proceed versus 5 hours on standard gamma camera

Pre angioplasty stress 201-thallium stress test Figure 1. Exercise thallium stress test images before angioplasty exhibiting significant reversible ischemia in the septal, anterior, and apical walls. Rows A and B are short-axis views of poststress and resting imaging, respectively. Rows C and D are vertical long-axis views of poststress and resting imaging, respectively. Rows E and F are horizontal long-axis views of poststress and resting imaging, respectively. Klein J J et al. Circulation 2004;109:e191-e193

Dual Isotope 201Tl 5 Min Stress / 99mTc Rest MIBI 3 Min

Dual Isotope LAD Territory 201Tl Pharmacologic / 99mTc Rest Patient: 67 yr male weight: 79 kg Indication: CABG 2006 PCI to LAD No chest pain / SOB MVA LOC Angiography : Normal grafts Procedure: Low dose 201Tl / 99mTc-MIBI

Average Dose Reduction 99mTc Activities (MBq) Dual Detector Sodium Iodide CZT Reduction Rest First 400 220 -45% Stress 900 590 201Tl Activities (MBq) Dual Detector Sodium Iodide CZT Reduction Stress 150 56 -63% Redistribution 50 15 -70%

Standard SPECT vs D530c CZT MPI August 2011-April 2013 Dual isotope Tc Studies only

Ultrafast Parathyroid 3D CZT SPECT ‘Standard’ tracer administered radioactivities – 10 minute scan Does however allow for lower injected activities - ~30 - 50% reduction Dual isotope 201Thallium / 99mTc (Thyroid) protocol possible Markedly improved study sensitivity and specificity over ‘standard’ NaI technology Excellent for the claustrophobic patient

Clinical features of parathyroid adenomas Characteristics % Gender Female 90 Male 10 Age (median 54.5 yrs) 20-40 9 40-70 83 >70 8 Localisation Right superior 6 Left superior 2 Right inferior 48 Left inferior 40 Intrathyroidal Bilateral inferior Smj 2006, vol:27

Parathyroid

Ultrafast parathyroid SPECT

Ultrafast parathyroid SPECT

Ultrafast parathyroid SPECT Patient: 60 yr female weight: 65 kg Indication: 1º Hyperparthyroidism Decreased Bone density Elevated Ca2+ and PTH

Ultrafast parathyroid 3D SPECT Patient: 60 yr female weight: 65 kg Indication: 1º Hyperparthyroidism Decreased Bone density Elevated Ca++ and PTH Procedure: ‘Small patient’ 6 minute scan

Parathyroid scan – ‘Conventional scanner’ Patient: 55 yr female weight: 75 kg Indication: 1º Hyperparthyroidism Elevated Ca++ and PTH Previous Parathyroid (other institution) scan NAD Procedure: ‘Small patient’ 8 minute scan

Ultrafast parathyroid 3D SPECT Patient: 55 yr female weight: 75 kg Indication: 1º Hyperparthyroidism Elevated Ca++ and PTH Previous Parathyroid (other institution) scan NAD Procedure: ‘Small patient’ 8 minute scan ‘Standard’ MPI filter Customised filter

Ultrafast Bone 3D SPECT Patient: 20 yr female weight: 60 kg Indication: Signs of Mandibular condyle hyperplasia

The Sentinel Node Concept

Breast sentinel node 3D SPECT Patient: 39 yr female weight: 65 kg Indication: Left Breast cancer ?

Breast sentinel node 3D SPECT Patient: 39 yr female weight: 65 kg Indication: Left Breast cancer

Discussion What has been the impact of this innovative technology? Significantly reduced patient radiation burden Markedly improved image quality ‘Real time’ 3D volumetric acquisition and reconstruction Significantly reduced scanning times Myocardial perfusion and ‘Other’ structures imaging proving to be fast, demonstrating excellent image resolution, and clinical improved sensitivity Improved patient journey and comfort As production costs decline, the technology will become more ‘mainstream

White light Ultraviolet light

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