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DIAGNOSTIC PERFORMANCE OF LOW-DOSE ATTENUATION-CORRECTED REST/STRESS Tc-99m TETROFOSMIN MYOCARDIAL PERFUSION SPECT USING THE DNM530C CZT CAMERA (QUANTITATIVE VERSUS EXPERT VISUAL ANALYSIS) FP Esteves, RD Folks, L Verdes, JR Galt, EV Garcia, Emory University School of Medicine, Atlanta, GA Objective 1Esteves FP, Raggi P, Folks RD, Keidar Z, Askew JW, Rispler S, O'Connor MK, Verdes L, Garcia EV. Novel solid-state-detector dedicated cardiac camera for fast myocardial perfusion imaging: multicenter comparison with standard dual detector cameras. J Nucl Cardiol. 2009 Nov-Dec;16(6):927-34. Discovery NM 530c System Design Pharm or Exercise Rest imaging 0 min Pinhole projections for stress (20 mCi, 6 minute acquisition) and rest (6 mCi, 8 minute acquisition) acquired on the DNM 530c SPECT system. 5-7 min Stress imaging 1 hr 2 hr All patients received a dose of 6 mCi at rest and 20 mCi at stress. Rest images were obtained over 7, 8, or 9 minutes and stress over 5, 6, or 7 minutes depending on chest size. On the same day, low dose CT (average 0.4 mSv) of the patient’s thorax was obtained on a standalone CT scanner using a shallow free breathing protocol. CT images were imported and manually registered with the SPECT images prior to reconstruction (MLEM) with AC using the manufacturer’s software. Patient Characteristics Low Likelihood Pilot Validation Normalcy Sample size 40 150 55 40 Male/Female 20/20 78/72 31/24 14/26 53 ± 9 Age ± % std. dev. 50 ± 11 63 ± 12 63 ± 11 BMI ± % std. dev. 29 ± 6 28 ± 5 29 ± 5 29 ± 5 Chest pain 0% (0) 75% (112) 82% (45) 0% (0) Exercise stress 100% (40) 59% (88) 20% (11) 38% (15) Stress Rest CT Low dose CT scan acquired on a stand-alone CT scanner on the same day of the SPECT. Multi pinhole technology • CZT detectors • 2.46 mm detectors The normal database for DNM 530c rest/stress AC Tc-99m tetrofosmin myocardial perfusion SPECT is shown above right in the form of a polar plot. A single database is used for both sexes. * Stress Manual software registration of the Stress and Rest SPECT scans (reconstructed without AC) with the CT. Note that the same CT is used for both Stress and Rest SPECT scans. Rest Normal Database Development ECTb software was used for processing and interpretation. Forty patients with low (<5%) likelihood (LLK) of coronary artery disease (CAD) were used to define the normal count distribution. An expert reader scored a pilot group of 150 patients using the 17-segment LV model on a 5-point scale (0-4). Optimum criteria for abnormality were determined by ROC curve analysis for each of 7 myocardial segments. Abnormality criteria were prospectively validated in 55 patients who had coronary angiography within 2 months of the SPECT and in 40 patients with LLK of CAD. Obstructive CAD was defined as a 70% luminal stenosis in at least one major coronary artery. AC Normal Database Specificity Stress (20 mCi) 7-9 min Combined Male/Female Acquisition and processing of DNM 530c SPECT with AC is illustrated below. Subject is a 60 year old female with history of myocardial infarction in the inferolateral wall who weighed 77kg (170 lbs), was 163 cm tall (5’4”), with a BMI of 29.2 kg/m2 at the time of imaging. Results - Overall Background The DNM 530c SPECT system has a unique design with 19 CZT detectors, each equipped with pinhole collimation, arranged in three rows surrounding the patient in a 180° RAO to LPO arc. During acquisition the detectors are stationary with the central row of (9) in line with the patient’s heart and rows above and below the heart (5 each) providing views in a more longitudinal direction. Compared to standard SPECT systems, this multiple pinhole design provides very high sensitivity and allows for shorter imaging times and lower radiation doses.1 The unique detector also produces differences in attenuation patterns compared to conventional SPECT. In a study that compared DNM 530c SPECT to conventional SPECT, some patients with breast attenuation noted in the anterior wall on conventional SPECT had no loss of counts on D530c SPECT. Instead some of these patients had a mild count loss in the inferior wall.1 Attenuation correction may be performed on the DNM 530c by registering the SPECT scan with a separately acquired CT scan, converting the CT Hounsfield units to 99mTc attenuation coefficients, and incorporating attenuation correction into the MLEM reconstruction. A routine procedure in the clinic where this study was performed, care is taken to position each patient on the CT scanner in the same manner as they are positioned for SPECT. Rest (6 mCi) Results Example Tc-99m Tetrofosmin SPECT Protocol Sensitivity To compare the diagnostic performance of quantitative analysis (QA) against visual analysis (VA) on rest/stress attenuation corrected (AC) Tc-99m tetrofosmin myocardial perfusion SPECT using the DNM530c CZT camera. Methods * P = 0.03 All others P = NS Visual and quantitative sensitivity and specificity by vascular territory and overall are shown using a 70% stenosis as criteria for obstructive CAD. Conclusions The overall diagnostic performance of quantitative attenuation correction is comparable to that of visual analysis in low-dose Tc-99m tetrofosmin myocardial perfusion SPECT with the DNM530c CZT camera. Quantitative analysis may increase physician’s confidence in image interpretation and can be particularly useful to cardiac readers unfamiliar with the DNM530c camera. Stress/Rest oblique slices and ECTb polar plots for non-AC (for comparison, on left) and AC. Blackout regions of the polar plots are determined by comparison to the normal database using the abnormality criteria. DISCLOSURE This work was funded by GE Healthcare. Two of the authors (RDF, EVG) and Emory University receive royalties from the sale of the Emory Cardiac Toolbox(TM) utilized in this poster. The terms of this arrangement have been reviewed and approved by Emory University in accordance with its conflict-of-interest practice.