Effect of reduced photon count levels and choice of normal data on semi-automated image assessment in cardiac SPECT

Wetzl, Matthias; Sanders, James C.; Kuwert, Torsten; Ritt, Philipp

doi:10.1007/s12350-018-1272-1

Cited by 7 publications

(6 citation statements)

References 38 publications

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“…The latest generations of dedicated cardiac SPECT cameras and advanced iterative reconstruction software methods (7)(8)(9)(10)(11) have enabled meaningful reductions in imaging time and radiopharmaceutical doses (12)(13)(14)(15)(16). However, if the reconstruction parameters are not adjusted for increased noise in the reduced-dose/time images, it may be necessary to use normal databases that are ''countmatched'' to avoid bias induced by the noise mismatch between the normal database and the reduced-dose/time images (15)(16)(17). Another factor that affects the normal perfusion distribution patterns is camera technology; Figure 3 illustrates examples of the mean normal perfusion polar map differences in regional relative perfusion between SPECT and PET normal patterns, standard SPECT versus cadmium-zinc-telluride imaging, and attenuation correction versus studies not corrected for attenuation.…”

Section: Established Clinical Applications Database Relative Myocardimentioning

confidence: 99%

Quantitative Clinical Nuclear Cardiology, Part 1: Established Applications

et al. 2019

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Learning Objectives: On successful completion of this activity, participants should be able to (1) know the basics of how quantitative parameters of relative left ventricular myocardial perfusion are measured and used clinically to differentiate patients with normal versus abnormal distributions; (2) know the basics of how quantitative parameters of left ventricular myocardial global and regional function is measured and used clinically to differentiate patients with normal versus abnormal function; and (3) describe and know how to use clinically nonperfusion quantitative parameters obtained from perfusion studies to modify the likelihood of the presence and extent of coronary artery disease in patients. Financial Disclosure: Dr. Moody is an employee of Invia. Dr. Slomka receives grants from the National Institutes of Health and Siemens Medical Systems and receives software royalties from Cedars-Sinai. Dr. Germano receives royalties from most nuclear medicine companies. Dr. Ficaro is an employee of Invia. Dr. Garcia receives grants from Syntermed and GE Healthcare and receives royalties from Syntermed. The authors of this article have indicated no other relevant relationships that could be perceived as a real or apparent conflict of interest. CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, SAM, and other credit types, participants can access this activity through the SNMMI website (http://www.snmmilearningcenter.org) through November 2022. SPECT myocardial perfusion imaging has attained widespread clinical acceptance as a standard of care for patients with known or suspected coronary artery disease. A significant contribution to this success has been the use of computer techniques to provide objective quantitative assessment in the standardization of the interpretation of these studies. Software platforms have been developed as a pipeline to provide the quantitative algorithms researched, developed and validated to be clinically useful so diagnosticians everywhere can benefit from these tools. The goal of this continuing medical education article (part 1) is to describe the many quantitative tools that are clinically established and, more importantly, how clinicians should use them routinely in interpretation, clinical management, and therapy guidance for patients with coronary artery disease.

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Section: Established Clinical Applications Database Relative Myocardimentioning

confidence: 99%

Quantitative Clinical Nuclear Cardiology, Part 1: Established Applications

et al. 2019

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“…While the diagnostic and prognostic advantages of dedicated cardiac SPECT systems are already well reported [ 1 , 2 , 16 – 18 , 23 , 26 ], the clinical use of general-purpose SPECT systems equipped with cardiac specific collimators is still very relevant [ 2 , 15 , 16 , 27 ]. In case of the heart-focused collimators the imaging performance [ 11 , 13 , 28 , 29 ] along with the accurate clinical use [ 12 , 30 – 34 ] has been already thoroughly investigated.…”

Section: Introductionmentioning

confidence: 99%

Performance evaluation of a novel multi-pinhole collimator on triple-NaI-detector SPECT/CT for dedicated myocardial imaging

et al. 2023

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Background In this study we evaluated the imaging capabilities of a novel Multi-pinhole collimator (MPH-Cardiac) specially designed for nuclear cardiology imaging on a Triple-NaI-detector based SPECT/CT system. Methods 99mTc point source measurements covering the field of view (FOV) were used to determine tomographic sensitivity (TSpointsource) and spatial resolution. Organ-size tomographic sensitivity (TSorgan) was measured with a left ventricle (LV) phantom filled with typical myocardial activity of a patient scan. Reconstructed image uniformity was measured with a 140 mm diameter uniform cylinder phantom. Using the LV phantom once filled with 99mTc and after with 123I, Contrast-to-noise ratio (CNR) was measured on the reconstructed images by ROI analysis on the myocardium activity and on the LV cavity. Furthermore, a polar map analysis was performed determining Spill-Over-Ratio in water (SORwater) and image noise. The results were compared with that of a dual-head parallel-hole low energy high resolution (LEHR) collimator system. A patient with suspected coronary artery disease (CAD) was scanned on the LEHR system using local protocol of 16 min total acquisition time, followed by a 4-min MPH-Cardiac scan. Results Peak TSpointsource was found to be 1013 cps/MBq in the axial center of the FOV while it was decreasing toward the radial edges. TSorgan in the CFOV was found to be 134 cps/MBq and 700 cps/MBq for the LEHR and MPH-Cardiac, respectively. Average spatial resolution throughout the FOV was 4.38 mm FWHM for the MPH-Cardiac collimator. Reconstructed image uniformity values were found to be 0.292% versus 0.214% for the LEHR and MPH-Cardiac measurements, respectively. CNR was found to be higher in case of MPH-Cardiac than for LEHR in case of 99mTc (15.5 vs. 11.7) as well as for 123I (13.5 vs. 8.3). SORwater values were found to be 28.83% and 21.1% for the 99mTc measurements, and 31.44% and 24.33% for the 123I measurements for LEHR and MPH-Cardiac, respectively. Pixel noise of the 99mTc polar maps resulted in values of 0.38% and 0.24% and of the 123I polar maps 0.62% and 0.21% for LEHR and MPH-Cardiac, respectively. Visually interpreting the patient scan images, MPH-Cardiac resulted in better image contrast compared to the LEHR technique with four times shorter scan duration. Conclusions The significant image quality improvement achieved with dedicated MPH-Cardiac collimator on triple head SPECT/CT system paves the way for short acquisition and low-dose cardiovascular SPECT applications.

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“…Two studies have shown that when a cardiofocal collimator is used instead of a LEHR collimator, the injected activity is reduced by up to 67% [12] or a factor of four [13]. However, neither study proposed how to tailor the injected activity to the individual patient, nor did they determine the degree of patient size-related gamma-ray signal attenuation.…”

Section: Introductionmentioning

confidence: 99%

Personalization of 99mTc-sestamibi activity in SPECT/CT myocardial perfusion imaging with the cardiofocal SmartZoom® collimator

et al. 2023

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Background Patient radioprotection in myocardial perfusion imaging (MPI)-SPECT is important but difficult to optimize. The aim of this study was to adjust injected activity according to patient size—weight or BMI—by using a cardiofocal collimator camera. Methods The correlation equation between size and observed counts in image was determined in patients who underwent stress Tc-99m-sestamibi MPI-SPECT/CT with a cardiofocal collimator-equipped conventional Anger SPECT/CT system. Image quality analyses by seven nuclear physicians were conducted to determine the minimum patient size-independent observed count threshold that yielded sufficient image quality for perfusion-defect diagnosis. These data generated an equation that can be used to calculate personalized activity for patients according to their size. Results Analysis of consecutive patients (n = 294) showed that weight correlated with observed counts better than body mass index. The correlation equation was used to generate the equation that expressed the relationship between observed counts, patient weight, and injected activity. Image quality analysis with 50 images yielded an observed count threshold of 22,000 counts. Using this threshold means that the injected activity in patients with < 100 kg would be reduced (e.g., by 67% in 45-kg patients). Patients who are heavier than 100 kg would also benefit from the use of the threshold because although the injected activity would be higher (up to 78% for 150-kg patients), good image quality would be obtained. Conclusions This study provided a method for determining the optimal injected activity according to patient weight without compromising the image quality of conventional Anger SPECT/CT systems equipped with a cardiofocal collimator. Personalized injected activities for each patient weight ranging from 45 to 150 kg were generated, to standardize the resulting image quality independently of patient attenuation. This approach improves patient/staff radioprotection because it reduces the injected activity for < 100-kg patients (the majority of patients).

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Effect of reduced photon count levels and choice of normal data on semi-automated image assessment in cardiac SPECT

Abstract: Significant bias results from count level of normal data relative to actual patient data. Compared to standard LEHR, IQ-SPECT should allow for significant dose reduction.

Cited by 7 publications

References 38 publications

Quantitative Clinical Nuclear Cardiology, Part 1: Established Applications

Quantitative Clinical Nuclear Cardiology, Part 1: Established Applications

Performance evaluation of a novel multi-pinhole collimator on triple-NaI-detector SPECT/CT for dedicated myocardial imaging

Personalization of 99mTc-sestamibi activity in SPECT/CT myocardial perfusion imaging with the cardiofocal SmartZoom® collimator

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