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Quantitation of SPECT cardiac perfusion images: Validation of a new automated analysis software based on radial slices
JOURNAL OF NUCLEARCARDIOLOGY Volume 2, Number 2, Part 2
Abstracts Monday afternoon, April 24, 1995
P06-137
PO6-139
PAPER VERSUS FILM FOR HARD COPY OF MYOCARDIAL PERFUSION TOMOGRAPHY: RECEIVER OPERATING CHARACTERISTIC (ROC) ANALYSIS.
RESOLUTION IMPROVEMENTS IN MYOCARDIAL SPECT WITH DOUBLE-HEADED SPECT SYSTEM. Y. Petegnief, A. Mure, R. Lebtahi, M. Faraggi, L. Sarda, D. Le Guludec. Bichat Hospital; Paris - France.
G A Hurwitz, P Slomka, RL Vandierendonck, JP O'Donoghue, DC Wilson, CL Willems, SK Ghali. University of Western Ontario, London, Canada. Rapid availability of high-quality copies of myocardial perfusion tomograms might facilitate (i)feedback in performing reconstruction, (ii) clinical review in patients experiencing symptoms, and(ill)communication by FAX. We assessed 48 rest/stress sestamibi studies performed and hard-copied during the first month after introduction of a new technique; at the time of reconstruction by technologists, reference views and mid-ventricular slices in 3 projections were printed on 1 l"x8" paper using a conventional 600 dpi laser printer. Studies archived on paper were blinded and read for presence and nature of defects by 4 nuclear medicine residents, and compared using ROC methods to standardized film copies formatted by one physician-author. Paper was similar to film in inter- and intra-observer variation, and in diagnostic accuracy. Subsequent routine use of paper prints has reduced costs and improved clinical service.
Double-headed SPECT systems with cameras at right angles offer a twofold gain in sensitivity for 180" myocardial SPECT. SophyCamera DST allows a myocardial dedicated orbit with heart centered on the axis of rotation (by adjusting bed height and gantry translation each step). We investigated the respective role of collimator and orbit selection on resolution improvements. A cardiac phantom containing 2O1TIand a 3 cm3cold defect was imaged with 3 collimators: high sensitivity, general purpose and high resolution (HR). Defect to normal contrast, calculated on short-axis slices (Hann filter, fc=0.5 cycles/cm) was respectively 0.44, 0.49, 0.55 and relative number of counts 2, 1.3, 1. This enabled the choice of HR collimators, combining two heads sensitivity and gain in resolution. For a 75 mm left off-axis 9~nTc line source and HR, transaxial full width half medium (FWHM) was 14.7mm in both radial and tangential directions when source is centered and 15.7 mm radial FWHM and 12.2 mm tangential FWHM Without centered acquisition. Thus, symetry of spatial resolution over the myocardium was obtained with heart-centered setting without loss of resolution due to the complexity of system motion. Optimal clinical acquisition parameters derived from 10 normal patients exercise data (111MBq of 2~ were 50 sec/view giving a total time of acquisition of 14 rain and 2.45 Mcounts.
P06-138
PO6-140
LOWER SPECIFICITY OF 201TL-MYOCARDIAL-STRESS SCINTIGRAPHY - WHY IT IS: A RESULT OF ROUTINE QUALITY-CONTROL IN NUCLEAR-CARDIOLOGY. L.Fridrich, M.Chamieh, V,Mtihlberger, N.Moes, G.Friedrich, G.Riceabona. Univ.Clinic of Nuclear Medicin and Departement of Invasive Cardiology University Innsbruek, AUSTRIA Out of 2252 patiens(pts) investigated by planar 201TIMyocardial-Stress-Sc.(MSC) - in 22% of pts also coronary angiography(CA) was performed. To introduce quality control in routine nuclear cardiology a random sample initally judged by an experienced nuclear cardiologist has been retrospectively compared to the results of CA by an invasive cardiologist not involved in performance or judgement of MSC or CA. Results: For individual patients CAD detection Sensitivity(SENS) and Speeificity(SPEC) was 100 and 18% respectively ; according to individual coronary artery regions SENS and SPEC was for LAD 83 and 42%, for RCA 94 and 44%, for RCX 55 and 94% respectively. In the 14 pts without SCAS but pos MSC 10 had arterial hypertension with diffuse calcified coronary sclerosis in 7 pts, another patient had inducable coronary spasm and two pts were judged equivocal by MSC. Conclusions: pts with CAD and number of diseased vessels were detected with good sensitivity by MSC, however pts without SCAS revealed other pathophysiologic correlates explaining detected perfusion abnormalities and thus low specificity.
QUANTITATION OF SPECTCARDIAC PERFUSION IMAGES : VALIDATION OF A NEW ,AUTOMATED ANALYSIS SOFTWARE BASED ON RADIAL SLICES. Th. Benoit, D. Vivegnis, M.P. Larock, J. Foulon, P. Rigo. CHU SART-T~LMAN,Liege, Belgium. We have developed a new automated software using a 360~ elliptical sampling of radial slices, circumferential profiles and a polar summarj display for myocardial SPECT perfusion imaging quantitative analysis. Partial volume effects are homogeneoulsy distributed in all orientations and data are corrected pixel by pixel for surface distortion resulting from planar projection. Threshold for abnormality is fixed pixel by pixel as normal mean (NM) - 2.5 SD. Defect severity is defined as NM - patient value (pt) over NM - pt background in abnormal regions. An ischemic size index (ISI) (defect surface x defect severity) is calculated to eliminate the surface overestimation and severity underestimation effects of diffusion. The ISI reproducibility is 3.5% for pts studies while RSD reaches 6% for cardiac phantom studies because of a geometrical discrepancy between the ellipsoid model used and the phantom cylindrical shape. Linear regression between phantom defects of various known sizes and corresponding calculated ISI demonstrates excellent correlation (r: 0.992) with only a slight overestimation of very small size defects.
$35
Abstracts Monday afternoon, April 24, 1995
P06-137
PO6-139
PAPER VERSUS FILM FOR HARD COPY OF MYOCARDIAL PERFUSION TOMOGRAPHY: RECEIVER OPERATING CHARACTERISTIC (ROC) ANALYSIS.
RESOLUTION IMPROVEMENTS IN MYOCARDIAL SPECT WITH DOUBLE-HEADED SPECT SYSTEM. Y. Petegnief, A. Mure, R. Lebtahi, M. Faraggi, L. Sarda, D. Le Guludec. Bichat Hospital; Paris - France.
G A Hurwitz, P Slomka, RL Vandierendonck, JP O'Donoghue, DC Wilson, CL Willems, SK Ghali. University of Western Ontario, London, Canada. Rapid availability of high-quality copies of myocardial perfusion tomograms might facilitate (i)feedback in performing reconstruction, (ii) clinical review in patients experiencing symptoms, and(ill)communication by FAX. We assessed 48 rest/stress sestamibi studies performed and hard-copied during the first month after introduction of a new technique; at the time of reconstruction by technologists, reference views and mid-ventricular slices in 3 projections were printed on 1 l"x8" paper using a conventional 600 dpi laser printer. Studies archived on paper were blinded and read for presence and nature of defects by 4 nuclear medicine residents, and compared using ROC methods to standardized film copies formatted by one physician-author. Paper was similar to film in inter- and intra-observer variation, and in diagnostic accuracy. Subsequent routine use of paper prints has reduced costs and improved clinical service.
Double-headed SPECT systems with cameras at right angles offer a twofold gain in sensitivity for 180" myocardial SPECT. SophyCamera DST allows a myocardial dedicated orbit with heart centered on the axis of rotation (by adjusting bed height and gantry translation each step). We investigated the respective role of collimator and orbit selection on resolution improvements. A cardiac phantom containing 2O1TIand a 3 cm3cold defect was imaged with 3 collimators: high sensitivity, general purpose and high resolution (HR). Defect to normal contrast, calculated on short-axis slices (Hann filter, fc=0.5 cycles/cm) was respectively 0.44, 0.49, 0.55 and relative number of counts 2, 1.3, 1. This enabled the choice of HR collimators, combining two heads sensitivity and gain in resolution. For a 75 mm left off-axis 9~nTc line source and HR, transaxial full width half medium (FWHM) was 14.7mm in both radial and tangential directions when source is centered and 15.7 mm radial FWHM and 12.2 mm tangential FWHM Without centered acquisition. Thus, symetry of spatial resolution over the myocardium was obtained with heart-centered setting without loss of resolution due to the complexity of system motion. Optimal clinical acquisition parameters derived from 10 normal patients exercise data (111MBq of 2~ were 50 sec/view giving a total time of acquisition of 14 rain and 2.45 Mcounts.
P06-138
PO6-140
LOWER SPECIFICITY OF 201TL-MYOCARDIAL-STRESS SCINTIGRAPHY - WHY IT IS: A RESULT OF ROUTINE QUALITY-CONTROL IN NUCLEAR-CARDIOLOGY. L.Fridrich, M.Chamieh, V,Mtihlberger, N.Moes, G.Friedrich, G.Riceabona. Univ.Clinic of Nuclear Medicin and Departement of Invasive Cardiology University Innsbruek, AUSTRIA Out of 2252 patiens(pts) investigated by planar 201TIMyocardial-Stress-Sc.(MSC) - in 22% of pts also coronary angiography(CA) was performed. To introduce quality control in routine nuclear cardiology a random sample initally judged by an experienced nuclear cardiologist has been retrospectively compared to the results of CA by an invasive cardiologist not involved in performance or judgement of MSC or CA. Results: For individual patients CAD detection Sensitivity(SENS) and Speeificity(SPEC) was 100 and 18% respectively ; according to individual coronary artery regions SENS and SPEC was for LAD 83 and 42%, for RCA 94 and 44%, for RCX 55 and 94% respectively. In the 14 pts without SCAS but pos MSC 10 had arterial hypertension with diffuse calcified coronary sclerosis in 7 pts, another patient had inducable coronary spasm and two pts were judged equivocal by MSC. Conclusions: pts with CAD and number of diseased vessels were detected with good sensitivity by MSC, however pts without SCAS revealed other pathophysiologic correlates explaining detected perfusion abnormalities and thus low specificity.
QUANTITATION OF SPECTCARDIAC PERFUSION IMAGES : VALIDATION OF A NEW ,AUTOMATED ANALYSIS SOFTWARE BASED ON RADIAL SLICES. Th. Benoit, D. Vivegnis, M.P. Larock, J. Foulon, P. Rigo. CHU SART-T~LMAN,Liege, Belgium. We have developed a new automated software using a 360~ elliptical sampling of radial slices, circumferential profiles and a polar summarj display for myocardial SPECT perfusion imaging quantitative analysis. Partial volume effects are homogeneoulsy distributed in all orientations and data are corrected pixel by pixel for surface distortion resulting from planar projection. Threshold for abnormality is fixed pixel by pixel as normal mean (NM) - 2.5 SD. Defect severity is defined as NM - patient value (pt) over NM - pt background in abnormal regions. An ischemic size index (ISI) (defect surface x defect severity) is calculated to eliminate the surface overestimation and severity underestimation effects of diffusion. The ISI reproducibility is 3.5% for pts studies while RSD reaches 6% for cardiac phantom studies because of a geometrical discrepancy between the ellipsoid model used and the phantom cylindrical shape. Linear regression between phantom defects of various known sizes and corresponding calculated ISI demonstrates excellent correlation (r: 0.992) with only a slight overestimation of very small size defects.
$35