– – The clinical utility of The clinical utility of ultrafast cardiocentric 3D ultrafast cardiocentric 3D

SPECT novel semi-conductor SPECT novel semi-conductor scanner technology scanner technology ––

Berry Allen PhD 31 August 2013Berry Allen PhD 31 August 2013

• 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

Nuclear Medicine (Molecular Imaging) 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

Gamma Camera Principles

Conventional (Gamma) camera configurationConventional (Gamma) camera configuration

Semi conductor (CZT) detectorsSemi 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

• NoNo reconstruction resolution recovery or collimator recovery algorithms / processing required

• 530c - 4.6 mm spatial resolution 4.6 mm spatial resolution (pin hole collimation)

• 5% – 6% Energy resolution (NaI crystal ~ 11 - 13%)5% – 6% Energy resolution (NaI crystal ~ 11 - 13%)

D-SPECT D-SPECT scannerscanner

Stationary semi conductor Cardiac scannersStationary semi conductor Cardiac scanners

530c Scanner530c Scanner

Garcia et al JNM Vol. 52 • No. 2 • February 2011

• SSingle Photon Emission Computed Tomography SPECT 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)(Fig A)

• Novel dedicated scanner - all available detectors are constrained

to imaging just the cardiac field of view (Fig B)(Fig B)

GE D530c Stationary Data (Gantry) GE D530c Stationary Data (Gantry) AcquisitionAcquisition

Garcia et al JNM Vol. 52 • No. 2 • February 2011

GE D530c Stationary Data (Gantry) GE D530c Stationary Data (Gantry) AcquisitionAcquisition

Indirect radiation conversion with conventional SPECT detector (Fig A) (Fig A)

Direct radiation conversion with CZT detector (Fig B)(Fig B)

1 CZT Module

4 Modules in a Detector

1 Triplet with 3 Detectors

Module / Detector/ Triplet Assembly Module / Detector/ Triplet Assembly

• 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

D530c Stationary Data Gantry AcquisitionD530c Stationary Data Gantry Acquisition

ANGINAANGINA

RESTREST EXERCISEEXERCISE

NORMAL NORMAL

CORONARY STENOSISCORONARY STENOSIS

Pathophysiology of Coronary Artery Pathophysiology of Coronary Artery DiseaseDisease

Pathophysiology of Coronary Artery Pathophysiology of Coronary Artery DiseaseDisease

EXERCISE

REST

CORONARY BLOOD FLOW

PERCENT DIAMETER STENOSIS

0 50 100

CORONARY FLOW RESERVE

530c CZT / NaI Comparison99mTc based tracerPatient: 67 yr femaleweight: 50 kg

Indication: Atypical chest painPresurgical assessment

Procedure: Low dose Low dose stress (pharmacologic)

530 CZT6 min scan

NaI 20 min scan

530 CZT ‘Standard’ NaI

Dual energy Dual energy 201201Thallium – Thallium – 99m99mTc cardiac Tc cardiac imagingimaging

The ‘Ideal‘ optionThe ‘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 LOWLOW dose study.• Was a HIGH 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

Klein J J et al. Circulation 2004;109:e191-e193

Dual Isotope Dual Isotope 201201Tl 5 Min Stress / Tl 5 Min Stress / 99m99mTc Rest MIBI 3 MinTc Rest MIBI 3 Min

Dual Isotope LAD Territory Dual Isotope LAD Territory 201201Tl Pharmacologic / Tl Pharmacologic / 99m99mTc Tc RestRest

Patient: 67 yr maleweight: 79 kg

Indication: CABG 2006PCI to LADNo chest pain / SOB

MVA LOC Angiography : Normal grafts

Procedure: Low dose Low dose 201Tl / 99mTc-MIBI

Average Dose ReductionAverage Dose Reduction

Dual DetectorSodium Iodide

CZT Reduction

Rest First 400 220 -45%

Stress 900 590 -45%

99mTc Activities (MBq)

Dual DetectorSodium Iodide

CZT Reduction

Stress 150 56 -63%

Redistribution 50 15 -70%

201Tl Activities (MBq)

Ultrafast Parathyroid 3D CZT SPECTUltrafast 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

CharacteristicsCharacteristics %%

GenderGender

Female 90

Male 10

Age (median 54.5 yrs)Age (median 54.5 yrs)

20-40 9

40-70 83

>70 8

LocalisationLocalisation

Right superior 6

Left superior 2

Right inferior 48

Left inferior 40

Intrathyroidal 2

Bilateral inferior 2

Clinical features of parathyroid Clinical features of parathyroid adenomas adenomas

Smj 2006, vol:27

ParathyroidParathyroid

Ultrafast parathyroid SPECTUltrafast parathyroid SPECT

Ultrafast parathyroid SPECTUltrafast parathyroid SPECT

Patient: 60 yr femaleweight: 65 kg

Indication: 1º HyperparthyroidismDecreased Bone densityElevated Ca2+ and PTH

Ultrafast parathyroid 3D SPECTUltrafast parathyroid 3D SPECTPatient: 60 yr femaleweight: 65 kg

Indication: 1º HyperparthyroidismDecreased Bone densityElevated Ca++ and PTH

Procedure: ‘Small patient’6 minute scan

ParathParathyroid yroid scan – ‘Conventional scanner’scan – ‘Conventional scanner’Patient: 55 yr femaleweight: 75 kg

Indication: 1º HyperparthyroidismElevated Ca++ and PTHPrevious Parathyroid (other institution) scan NAD

Procedure: ‘Small patient’8 minute scan

Ultrafast parathyroid 3D SPECTUltrafast parathyroid 3D SPECTPatient: 55 yr femaleweight: 75 kg

Indication: 1º HyperparthyroidismElevated Ca++ and PTHPrevious Parathyroid (other institution) scan NAD

Procedure: ‘Small patient’8 minute scan

‘Standard’ MPI filter Customised filter

The Sentinel Node ConceptThe Sentinel Node Concept

Breast sentinel node 3D SPECTBreast sentinel node 3D SPECT

Patient: 39 yr femaleweight: 65 kg

Indication: Left Breast cancer ?

Breast sentinel node 3D SPECTBreast sentinel node 3D SPECT

Patient: 39 yr femaleweight: 65 kg

Indication: Left Breast cancer

DiscussionDiscussionWhat has been the impact of this innovative technology?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

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