Improved detection of coronary artery disease by planar TC-99M Tetrofosmin compared to Thallium-201 imaging

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Abstracts Wednesday morning, April 26, 1995

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P 17-375

CGP 12177 IS A BETA-BLOCKER WITH INTRINSIC SYMPATHOMIMETIC ACTIVITY.

CMNICAL DEMAND IN NUCLEAR CARDIOLOGY.

Hrric Valette, Andr6 Syrota, Chantal Fuseau. SHFJDRIPP-CEA, Orsay, France. l l C - C G P 12177 is used to assess myocardial betaadrenergic receptor density. During PET experiments in anaesthetized dogs, we observed an increase in heart rate following injection of CGP (ll.tg/kg) suggesting that CGP has an intrinsic sympathomimetic activity (ISA). Changes in left ventricular ejection fraction (LVEF, gated blood pool studies), fol!owing infusion of CGP (0.51~g/kg, lbtg/kg, 1,5 lag&g) or propranolol (Pro: 0.17mg/kg, 0.34 mg/kg, 0.68 mg/kg) which is devoided of ISA) were compared in 5 dogs.These doses of Pro have beta-blocking effects without increasing plasma norepinephrine concentration. Results (heart rate: HR): baseline 1st dose 2nd dose 3rd dose CGP HR 122+30 151+19 154+21 158+23 LVEF 68+11 82+5 82+12 91+8 Pro HR 126+28 116+28 115+18 113+15 LVEF 71+15 63+17 60_+10 58+11 ANOVA showed that the changes in HR and LVEF were different for the two drugs (p<0.003 and p<0.0001, respectively). Blood pressure and plasma norepinephrine remained unchanged with both compounds. These results strongly suggest that CGP has ISA. Therefore, CGP could be used rather safely in patients with left ventricular dysfunction.

P M A P R I L

Pieduigi Rossini, Raffaele Giubbini, Elisa Milan, Aurora Vaccari, Arturo Terzi, Mautfzio Bestagno. Nuclear Medicine Dpt, Civic Hospital, Brescia -Italy. Our Nuc. Cardiology Lab. is located in a 2000 bed University Hospital and it is a reference lab. to the Cardiology Dpts of 7 Community Hospitals in an area with over one million inhabitants. The clinical demand exceeds the maximum output of our lab. (approximately 2000-2500 studies per year). For this reason Cardiologists have to limit their requests to pts with mandatory indications for nuclear studies. From our database we extract on a yearly basis the indicalions to nuc. cardiology grouped in the following categories: 1990 1991 1992 1993 1994(normalised) CADdiagnosis 35.9%

502Y,

22.7%

24.8%

26.2%

Functionalaesessmentand risk stratificationof post.M/ pts 11,8%

'12.3%

9.2%

8.4%

8.2%

Functionalassessmentof coronarylesions

13.0%

10.0%

12.3%

9.8%

9.7%

1Q.8%

8.6%

14.5~

12.9%

1~,1%

9.0%

21.5%

25.7%

23.0~

19.7~

15.6O/o

21.1%

22.1%

3.3:1

2.6:1

2.6:1

2.5:1

2d :1

12:1

Evaluationof pts treatedby PTCAor by-passsurgery

Func~onalaeseesmentof LV performance

Vlablllty assessment 5.2~ I'12% MalM:emale 2,~;1

3.6:1

Exerclse/dlpyrldamole 2~4:1

_ 3:1

We conclude that in the last 5 years we have observed a progressive reduction of diagnostic tests (now approximately 25% of the overall demand) in favour of the functional evaluation of CAD pts, especially viability (4x) and vessel patency assessment after revascularization. The number of radionuclide angiographies and of studies performed for nsk stra~fication in the post MI pts is stable as well as the male/female ratio; the number of pham'acological stress tests is increasing in comparison to exercise.

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P 17-376

THE RABBIT IS A CONVENIENT SMALL ANIMAL TO S T U D Y M Y O C A R D I A L N O R E P I N E P H R I N E UPTAKE AND STORAGE WITH PET.

IMPROVED DETECTION OF CORONARY ARTERY DISEASE BY PLANAR TC-99M TETROFOSMIN COMPAREDTO THALLIUM-201IMAGING R S Khattar, J CW Crawley, U Raval, B S Sridhara, and A Lahiri. Northwick Park Hospital, Harrow, UK

Hrric Valette, Christian Loc'h, Bernard Mazi~re, Chantal Fuseau, Andr6 Syrota. SHFJ-CEA, Orsay, France.

W E D N E S D A Y

JOURNALOF NUCLEARCARDIOLOGY March/April 1995, Part 2

The drawback of the use of rats and dogs for the study of myocardial norepinephrine (NE) uptake - storage is the high (20%) extra-neuronal uptake. Dae has suggested, using 123I-MIBG scintigraphy and the neurotoxin 6-O1-I dopamine that the rabbit has a low uptake-2. In the present study we confirm these results using the bromoderivative of MIBG (76Br-MBBG). Three groups of 6 rabbits were studied: control, desipramine (40mg/kg) and 6-OH dopamine (50mg/kg). Animals were injected with 100~Ci in an ear vein and they were killed 30rain later, the heart rapidely removed, the left ventricle dissected and the radioactivity counted. Results: Control: 0.28+0.02 % ID/g/kg; Desipramine: - 92%; 6-OH dopamine: - 93%. These results confirm the low uptake-2 in this species. Three rabbits (mean weight: 4kg) were imaged for one hour using a human brain scanner (CT1953B/31). Injected doses were 300 to 6001.tCi. Myocardial uptake of MBBG was high with a plateau from the fifth minute after injection to the end of the experiment. Lung uptake showed a rapid wash-out of the tracer. Rabbits appear to be a convenient animal for the study of myocardial NE uptake - storage in viva.

Tc-99m tetrofosmin (Tet) is a new perfusion imaging agent which has advantages over TI-201 including superior image quality and dosimetry. The results of stress studies using planar Tat were compared with T1-201 by a blinded observer, in 38 patients with suspected coronary artery disease (CAD). Defects were allocated to the left anterior descending (LAD), right coronary (RCA) or left circumflex (LCX) arteries using a polar map with 3 levels of severity. Receiver operating characteristic (ROC) curves were plotted using angiographic data and the area under the ROC curve was used as a measure of diagnostic accuracy. ROC curves were created for the presence of CAD, multivessel (MV) and single vessel (SV) disease as well as for the three main arteries. Area under ROC curve 50% stenosis CAD MV SV LAD RCA LCX Tel 0.80 0.55 0.50 0.69 0.77 0.55 TI-201 0.67 0.55 0.58 0.70 0.66 0.53 70% stenosis Tet 0.85 0.55 0.55 0.75 0.57 0.55 T1-20I 0.58 0.55 0.55 0.75 0.55 0.45 This data suggests that there is an overall improvement for the detection of CAD by TeT compared to T1-201. Howeverthere is no difference in the localization of disease.