The diagnostic accuracy of cardiac single photon emission computed tomography (SPECT) is limited ... more The diagnostic accuracy of cardiac single photon emission computed tomography (SPECT) is limited by image-degrading factors, such as heart or subject motion, depth-dependent blurring caused by the collimator, and photon scatter and attenuation. We developed correction approaches for motion, depth-dependent blur, and attenuation and performed a multicenter validation. Motion was corrected both transversely and axially with a cross-correlation technique. Depth-dependent blurring was corrected by first back-projecting each projection and then applying a depth-dependent Wiener filter row by row. Attenuation was corrected with an iterative, nonuniform Chang algorithm, based on a transmission scan-generated attenuation map. We validated these approaches in 112 subjects, including 36 women (20 healthy volunteers, 8 angiographically normal patients, and 8 patients with coronary artery disease [CAD] found by means of angiography) and 76 men (23 healthy volunteers, 10 angiographically normal patients, and 43 patients with CAD found by means of angiography). Either technetium 99m or thallium 201 was used for emission; either gadolinium 153 or Tc-99m was used for transmission. Images were reconstructed and blindly interpreted with a 5-point scale for receiver operating characteristic analysis in 2 ways: motion correction plus a Butterworth filter, and combined motion and blur and attenuation corrections. The interpretation by means of consensus was for the overall presence of CAD and vascular territory. The receiver operating characteristic curves for overall presence and each of the 3 main coronary arteries were all shifted upward and to the left and had larger areas under the curve, for combined corrections compared with motion correction and Butterworth. Sensitivity/specificity for motion correction and Butterworth were 84/69, 64/71, 32/94, and 71/81 overall for the left anterior descending, the right coronary artery, and circumflex territories, respectively, compared with 88/92, 77/93, 50/97, and 74/95, respectively, for the combined corrections. The proposed combined corrections for motion, depth-dependent blur, and attenuation significantly improve diagnostic accuracy, when compared with motion correction alone.
Compared to filtered back projection (FBP), OSEM with resolution recovery (OSEM-RR) and wide beam... more Compared to filtered back projection (FBP), OSEM with resolution recovery (OSEM-RR) and wide beam reconstruction (WBR)(UltraSPECT Ltd.), which resolve resolution and suppress noise simultaneously during reconstruction, have been shown to maintain/improve myocardial perfusion SPECT quality, even with low count density half-time acquisitions. We postulated that their characteristics would be advantageous for gated SPECT, where each frame is only 1/8th the count density of the summed perfusion images. An 9 mCi rest/32 mCi (333/1184 MBq) stress Tc(99m) sestamibi protocol was used. 15-min FBP, and additional 7-min OSEM-RR and WBR post-stress 8-frame/cardiac cycle SPECT scans were acquired with 90 degrees -angled dual-headed detectors equipped with high resolution collimators in 156 patients. In 82 patients (48F, 34M) (123-252 lbs) with perfusion defects gated image quality was graded visually: 1 (poor)-5 (excellent) Regional LV wall motion (WM) was scored: 0 (normal)-4 (dyskinesis) in a total of 50 vascular territories with defects. Using Myometrix software (GE Healthcare), post-stress EDV, ESV, and EF were calculated for each method. Additionally, for purposes of comparison, the FBP gated tomograms were processed with other commercially available packages, Emory Toolbox and Cedars QGS. Despite half-time acquisitions, compared to FBP, image quality increased marginally with OSEM-RR (P = .09) but very significantly with WBR (P = 1.9 x 10(-21)). The WM score was greater only for WBR (P = 4.8 x 10(-8)). Although quantitative parameters correlated well with those determined by FBP (all EF r's > 0.85; all volume r's > 0.93), EFs were significantly lower (P = .0001 for OSEM-RR, 3.4 x 10(-14) for WBR), primarily due to a decrease in EDV with OSEM-RR (P = 7.3 x 10(-13)) and an increase in ESV with WBR (P = 9.2 x 10(-5)). However, inter-method differences in these parameters were of similar magnitude to differences encountered among the commercially available software methods. Half-time OSEM-RR and particularly WBR improve gated SPECT diagnostic quality compared to full-time FBP due to increased resolution and reduced noise. However, these attributes, which affect endocardial edge detection, result in a systematic offset in EDV, ESV, and EF.
Background. Nonuniform attenuation artifacts cause suboptimal specificity of stress single photon... more Background. Nonuniform attenuation artifacts cause suboptimal specificity of stress single photon emission computed tomography (SPECT) myocardial perfusion images. In phantoms, normal subjects, and patients suspected of having coronary artery disease (CAD), we evaluated a new hybrid attenuation correction (AC) system that combines x-ray computed tomography (CT) with conventional stress SPECT imaging.
Background. Our goal was to evaluate the ability of current commercially available attenuation co... more Background. Our goal was to evaluate the ability of current commercially available attenuation compensation (AC) techniques to correct for the effects of attenuation, scatter, and loss of resolution with depth, in a series of standardized phantom experiments.
The diagnostic accuracy of cardiac single photon emission computed tomography (SPECT) is limited ... more The diagnostic accuracy of cardiac single photon emission computed tomography (SPECT) is limited by image-degrading factors, such as heart or subject motion, depth-dependent blurring caused by the collimator, and photon scatter and attenuation. We developed correction approaches for motion, depth-dependent blur, and attenuation and performed a multicenter validation. Motion was corrected both transversely and axially with a cross-correlation technique. Depth-dependent blurring was corrected by first back-projecting each projection and then applying a depth-dependent Wiener filter row by row. Attenuation was corrected with an iterative, nonuniform Chang algorithm, based on a transmission scan-generated attenuation map. We validated these approaches in 112 subjects, including 36 women (20 healthy volunteers, 8 angiographically normal patients, and 8 patients with coronary artery disease [CAD] found by means of angiography) and 76 men (23 healthy volunteers, 10 angiographically normal patients, and 43 patients with CAD found by means of angiography). Either technetium 99m or thallium 201 was used for emission; either gadolinium 153 or Tc-99m was used for transmission. Images were reconstructed and blindly interpreted with a 5-point scale for receiver operating characteristic analysis in 2 ways: motion correction plus a Butterworth filter, and combined motion and blur and attenuation corrections. The interpretation by means of consensus was for the overall presence of CAD and vascular territory. The receiver operating characteristic curves for overall presence and each of the 3 main coronary arteries were all shifted upward and to the left and had larger areas under the curve, for combined corrections compared with motion correction and Butterworth. Sensitivity/specificity for motion correction and Butterworth were 84/69, 64/71, 32/94, and 71/81 overall for the left anterior descending, the right coronary artery, and circumflex territories, respectively, compared with 88/92, 77/93, 50/97, and 74/95, respectively, for the combined corrections. The proposed combined corrections for motion, depth-dependent blur, and attenuation significantly improve diagnostic accuracy, when compared with motion correction alone.
Compared to filtered back projection (FBP), OSEM with resolution recovery (OSEM-RR) and wide beam... more Compared to filtered back projection (FBP), OSEM with resolution recovery (OSEM-RR) and wide beam reconstruction (WBR)(UltraSPECT Ltd.), which resolve resolution and suppress noise simultaneously during reconstruction, have been shown to maintain/improve myocardial perfusion SPECT quality, even with low count density half-time acquisitions. We postulated that their characteristics would be advantageous for gated SPECT, where each frame is only 1/8th the count density of the summed perfusion images. An 9 mCi rest/32 mCi (333/1184 MBq) stress Tc(99m) sestamibi protocol was used. 15-min FBP, and additional 7-min OSEM-RR and WBR post-stress 8-frame/cardiac cycle SPECT scans were acquired with 90 degrees -angled dual-headed detectors equipped with high resolution collimators in 156 patients. In 82 patients (48F, 34M) (123-252 lbs) with perfusion defects gated image quality was graded visually: 1 (poor)-5 (excellent) Regional LV wall motion (WM) was scored: 0 (normal)-4 (dyskinesis) in a total of 50 vascular territories with defects. Using Myometrix software (GE Healthcare), post-stress EDV, ESV, and EF were calculated for each method. Additionally, for purposes of comparison, the FBP gated tomograms were processed with other commercially available packages, Emory Toolbox and Cedars QGS. Despite half-time acquisitions, compared to FBP, image quality increased marginally with OSEM-RR (P = .09) but very significantly with WBR (P = 1.9 x 10(-21)). The WM score was greater only for WBR (P = 4.8 x 10(-8)). Although quantitative parameters correlated well with those determined by FBP (all EF r's > 0.85; all volume r's > 0.93), EFs were significantly lower (P = .0001 for OSEM-RR, 3.4 x 10(-14) for WBR), primarily due to a decrease in EDV with OSEM-RR (P = 7.3 x 10(-13)) and an increase in ESV with WBR (P = 9.2 x 10(-5)). However, inter-method differences in these parameters were of similar magnitude to differences encountered among the commercially available software methods. Half-time OSEM-RR and particularly WBR improve gated SPECT diagnostic quality compared to full-time FBP due to increased resolution and reduced noise. However, these attributes, which affect endocardial edge detection, result in a systematic offset in EDV, ESV, and EF.
Background. Nonuniform attenuation artifacts cause suboptimal specificity of stress single photon... more Background. Nonuniform attenuation artifacts cause suboptimal specificity of stress single photon emission computed tomography (SPECT) myocardial perfusion images. In phantoms, normal subjects, and patients suspected of having coronary artery disease (CAD), we evaluated a new hybrid attenuation correction (AC) system that combines x-ray computed tomography (CT) with conventional stress SPECT imaging.
Background. Our goal was to evaluate the ability of current commercially available attenuation co... more Background. Our goal was to evaluate the ability of current commercially available attenuation compensation (AC) techniques to correct for the effects of attenuation, scatter, and loss of resolution with depth, in a series of standardized phantom experiments.
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Papers by Frank Anstett