NUCLEAR MEDICINE OF HEART AND LUNG

Transcription

1 Clinical decision tree in CAD NUCLEAR MEDICINE OF HEART AND LUNG Abnormal pump function Slides of lectures + electronic books: Stress-rest Stress: defect MPI Rest: better or normal Glucose metab? László Galuska Nothing to do Active ischemia Coronarography Revascularization Fixed defect ÁOK perfusion Present Viable hybernated No Scar Nothing to do TOK 2011 The role of risc factors! 1 2 Single photon isotop labelled PET Radiopharmaceuticals Summ. of myocard metabolism Radiopharmaceuticals for MPI (comparison) Thallium-chloride: K-analogue Redistribution may occur A single injection during stress Early images after 15 Late images after 3-4 h Metoxy-Iso-Butil-Isonitril (MIBI): Passes cells membranes passively (negative membrane potential). Accumulates in the mitrocondrias No redistribution Separate injections for stress and rest study (images after 60 ) Single-day protocol: 2 Starting with rest preferred ~ MBq Summary of myocardial substrate metabolism and PET tracers. FTHA 14(R,S)[18F]fluoro-6-thia-heptadecanoic acid, FOP 15-[18F]fluoro-3-oxapentadecanoate (Takashi Kudo nyomán) 3 4 RADIONUCLIDE STUDIES OF THE HEART Imaging in nuclear medicine. Gamma camera (up) Cardio - SPECT (down) SPECT-CT (up) PET-CT (down Ventricular wall motion Myocardial perfusion Myocardial glucose metabolism Hybrid technics (PET/CT, SPECT/CT 123I-MIBG 5 6 ECG gating Equilibrium ECG-gated ventriculography Pharmaceutical: [Tc-99m] in vivo labelled red blood cells (with pyrophosphate) Phenomenon Changing blood content of the ventricles imaged: and atria during the cardiac cycle Acquisition ECG-gated, averaging some hundreds of mode cycles. Quantitative Left (and right) ventricular ejection parameters: fraction Peak filling and emptying rate Left ventricular volume 7 8

2 ECG-gated RN ventriculography: apical aneurism 9 10 Myocardial perfusion scintigraphy Myocardial perfusion scintigraphy: Indications - 1 Pharmaceuticals: [Tl-201] Thallium-chloride or [Tc-99m] isonitrile derivatives (e.g. "MIBI") Phenomenon Myocardial perfusion after ergometric or imaged: pharmaceutical stress and in resting state. Abnormalities "Fix defect" (decreased activity in both the shown: stress and rest images) in scars. Reversible perfusion defect in ischeamic regions: Relatively decreased activity uptake (as compared to the healthy myocardium) in the regions of stenosed coronary arteries, not or less shown in rest (Tl: delayed) images. Suspicion of CAD with abnormal rest or indeterminate stress ECG Localization and severity of ischaemia Interpreting the (abnormal) result of coronarography (collaterals, microvasculature); assessing haemodynamic effects of the stenosis Result of surgical or catheteric intervention Prognosis of CAD Myocardial perfusion scintigraphy: Indications - 2 Assessing the location and severity of ischaemia in case of post-infarct angina for angioplasty Assessing myocardial viability in severe left ventricular insufficiency after infarct Cardiac risk stratification before major (chest, abdominal) surgery Planar projections and coronary vessel territories Imaging techniques: I. planar II. tomograhic (SPECT; PET) Redistribtion by TlCl Coronary artery territories on SPECT views 15 16

3 Polar map SHORT AXIS SLICES A. RCA B. Aortic arch C. Pulmonary artery D. LCA E. LCX F. LAD 17 Reverzible defect: short axis slices 18 Reverzible defect: vertical long axis slices 19 Reverzible defect: horizontal long axis slices 20 Reverzible defect: bull s eye 21 Fix defect: horizontal long axis slices 22 Fix defect: bull s eye 23 24

4 Viable: short axis sl. Viable: bull s eye DISA: Perf+metab. fix defect: non viable scar DISA: Perf and metabolic mismach: short ax Hybrid technics: 64 (or more) slice CTA and MPI with image fusion Hybrid technics: The parameters of 64 slice CT are suitable for noninvasiv investigation of structure of coronary arteries. In one hybrid system are the CT (structure) and metabolic (functional) informations! The main question: where is ischemia? The perfusion stress /rest Images and their fusion answer it. a, b Semiquantitative polar maps of perfusion during vasodilator stress (a) and at rest (b), showing a reversible perfusion defect at the lateral base (arrowheads). For presentation purposes, functional (MPI) and morphological (CTA) information was fused, generating three-dimensional (3D) volume-rendered SPECT/CT images. c Anterior view of fused 3D SPECT-CT images showing serial lesions of the prominent first diagonal branch (arrows) which are not haemodynamically relevant. d The lateral view shows a subtotal or total occlusion of the mid LCX (arrows) and the corresponding ischaemia (arrowheads) matching the territory of the LCX 29 PET in cardiology: NH3 PET blod flow & FDG viability 13-N-NH3 rest 18-F-FDG viability oblique slices 30 PET in cardiology: 82 Rb PET blod flow 1850 MBq 82Rb, 4 min. p.i. total acq. time: 4.5 min. including em. + transm. 13-N-NH3 stress flow & viability at same high sensitivity at same day partial match as blood supply vanishes myocardium dies dynamic/gated possible Images courtesy of Dr. A. Alavi, Univ. of Pennsylvania Hospital, Philadelphia very short half life (72 s) tracer w. long positron travel range generator isotope still good image quality w/o artifacts from high activity in liver Images courtesy of Dr. Blaufox, Montefiore Hospital, New York 31 32

5 Dynamics of norepinephrine and 123J-MIBG. Method of calculating the H/M ratio and washout rate on 123J-MIBG planar images a Norepinephrine (NE) is stored in synaptic vesicles at sympathetic nerve endings and is released via exocytosis due to nerve excitement. Most of the released NE returns to the nerve ending via the re-absorption mechanism designated as uptake-1. A fraction of the released NE becomes bound to the receptors, while the remaining part is released into the blood by spillover. The NE is ultimately inactivated by COMT and MAO. b MIBG is also incorporated into nerve endings via uptake-1, and released via the excitement of nerves, in a manner similar to NE. MIBG, however, is neither bound to the receptors nor degraded by enzymes. Owing to these characteristics, most of the MIBG is reabsorbed via uptake-1, and retained in the nerve ending for many hours Evaluation of risk areas in acute coronary syndrome Usefulness of 123J-MIBG in HCM One case of unstable angina in which MIBG was of diagnostic value. Female, aged 62 years. The patient was admitted to the hospital owing to a diagnosis of unstable angina, but no significant findings were obtained on 201TlCl myocardial perfusion SPECT at rest. MIBG showed decreased accumulation in the infero-posterior wall. On the delayed image, increased washout was observed at the same site, and the abnormal findings became more marked. On coronary angiography performed later, advanced stenosis was recognised in the proximal part of the right coronary artery Prediction of the therapeutic effects of β-blockers by MIBG myocardial scintigraphy (quoted from [59]). In 53 patients with dilated cardiomyopathy who received β-blocker therapy continuously for 6 months or longer, MIBG myocardial scintigraphy was performed twice, before and 6 12 months after the start of the treatment. The improvement in the washout rate after treatment was the strongest predictor of prognosis. No cardiac events occurred in the group of patients showing an improvement in washout rate by 10% or more following β- blocker therapy. Table 1 shows the relationship of various clinical characteristics to washout rate improvement by β-blocker therapy. Lower values of the extent score and higher values of the washout rate on the early image were predictive of washout rate improvement by β- blocker therapy and were thus also predictive of a favourable long-term prognosis Principles of Lung structure The nuclear medicine of lung Combined lung investigations (perfusion-ventillation) Matching perf./vetill. defect Tc99m-aeroszol Kr-81m Xe-133 primary airway obstruction secondary vasospasm Tc-99m-MAA: 20um 38 Combined lung investigations Radiopharmaceuticals Perf./inhal. mismach Tc99m-aeroszol Kr-81m Xe-133 bronchokonstrikció válasz a hypoxiára 99mTc T1/2: 6 h generátor-termék 140 kev gammasugárzás makroaggregats----perfusion microsphaers perfusion aerosols ventillation foszfonats bone scan Tc-99m-MAA: mean 20um 39 40

6 Radiopharmaceuticals for ventillation studies Clinical indications: Solubil: (DTPA, MDP) Non solubil: (HSA, Technegas, vvt.) Kr-81m gas Nebulisers: Pressed air: (MEDI61, Venticis) Ultrasonography: (Solcovent) Alkoholic solution with vacuum: (APE) Noble gas Pulmonary embolisation: Combined perf. and ventill. Study, 6 directions Before lung operation: to measure the ventill. capacity Developmental disorders of lung: perf and ventill Art. Pulm agen. Demage of alveolocapillary junction: alveolitis dynamic ventillation scintigraphy The causes of perfusional abnormalities 99mTc-MAA perfusion and 81mKr ventillation study pulmonary embolisation (trombus, sepsys, fat, air ) tumor/or hylar adenopathia vasculitis a. pulm. atresia seu hypoplasia Fibrotisating mediastinitis AVM a. pulmonary sarcoma intravenous drug TBC External radiation Matching perfusion and ventill. defect Art. Pulm. agenesia DTPA clearance Faster DTPA clearance (smoking!) Dinamic inhalation scintigrphy 99m-Tc DTPA clearance is faster: smoking ( reversibil) alveolitis Sarcoidosis pneumonitis Flame inhalation (fireman!) interstitial pneumonia lung manifestations of Immunological illneses 47 48