Gated Tomographic Radionuclide Angiography Using CZT Gamma Camera in Patients Receiving Cardiotoxic Chemotherapy: Going Faster and Less Irradiating.

Tomographic radionuclide angiography (TRNA) can monitor cardiac function in patients receiving cardiotoxic chemotherapy. Gamma cameras using CZT detectors enable dose reduction and quicker acquisitions. We report 80 patients who underwent a 7-minute TRNA acquisition after injection of 550-MBq Tc-labeled human serum albumin. Data were analyzed full and half. Image quality was not visually decreased. There was no significant difference in left ventricular systolic and diastolic volumes and in left and right ventricular ejection fractions between full and half data acquisitions (P < 0.0001). When injecting half activity, effective dose could be reduced to 1.92 mSv.

Paraganglioma aórtico del órgano de Zuckerckandl asociado a síndrome paraganglionar familiar por mutación de SDHB / Organ of Zuckerkandl paraganglioma associated with familial paraganglioma syndrome due to SDHB mutation

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Radiation reduction and faster acquisition times with SPECT gated blood pool scans using a high-efficiency cardiac SPECT camera.

BACKGROUND: Planar gated blood pool scans are an established method for the evaluation of left ventricular ejection fraction (LVEF) but the camera technology used for these studies has not significantly changed in decades. The purpose of this study was to determine the diagnostic accuracy of new high-efficiency SPECT gated blood pool scans compared to traditional scans and determine if they can be performed with lower radiation doses or faster acquisition times. METHODS: Patients undergoing a planar gated blood pool scan on a Na-I SPECT camera who consented to participate were subsequently imaged for 5 minutes in "List Mode" using a high-efficiency SPECT camera. LVEF was calculated for both the planar study and at 1, 2, 3, 4, and 5 minutes of acquisition on the high-efficiency camera. Counts acquired in the field of view, counts in the cardiac blood pool and LVEF were compared. RESULTS: A total of 46 patients were analyzed (48% male, mean age 55 years, and BMI 27.6 kg/m(2)) who received an average Tc-99m dose of 20.3 mCi (5.3 mSv), 17 (37%) with abnormal LVEF's. The Na-I camera averaged 24,514 counts/min/mCi in the field of view and 8662 counts/min/mCi in the cardiac blood pool while the high-efficiency camera averaged 65,219 counts/min/mCi and 41,427 counts/min/mCi, respectively. Compared to the planar calculation of LVEF, 1-minute SPECT LVEF was on average 8.6 ± 10.7 higher, 2 minutes 3.5 ± 7.6 higher, 3 minutes 2.9 ± 8.5 higher, 4 minutes 2.5 ± 7.0 higher, and 5 minutes 1.1 ± 6.2 higher. Good correlation was seen between the SPECT LVEF's and the planar LVEF's across all acquisition times with correlation coefficients of 0.74-0.93. CONCLUSIONS: High-efficiency SPECT technology can reduce radiation exposure to patients during gated blood pool imaging or decrease acquisition time while maintaining diagnostic accuracy. Based on the improved count sensitivity with high-efficiency SPECT, a 50% reduction in injected activity may be achievable while maintaining short imaging times of 5 minutes, with further reduction possible at longer imaging times.

Pre-chemotherapy values for left and right ventricular volumes and ejection fraction by gated tomographic radionuclide angiography using a cadmium-zinc-telluride detector gamma camera.

BACKGROUND: Estimation of left ventricular ejection fraction (LVEF) using equilibrium radionuclide angiography is an established method for assessment of left ventricular function. The purpose of this study was to establish normative data on left and right ventricular volumes and ejection fraction, using cadmium-zinc-telluride SPECT camera. METHODS AND RESULTS: From routine assessments of left ventricular function in 1172 patients, we included 463 subjects (194 men and 269 women) without diabetes, previous potentially cardiotoxic chemotherapy, known cardiovascular or pulmonary disease. The lower limits defined as mean value minus two standard deviations for ventricular ejection fraction and end diastolic volume were LVEF (men: 50%, women: 50%), LEDV (men: 45 mL, women: 40 mL), RVEF (men: 29%, women: 28%), and REDV (men: 73 mL, women: 57 mL).There was a significant negative correlation between age and both left and right ventricular volumes in women (r = -0.4, P < .001) but only for right end systolic ventricular volume in men (r = -0.3, P = .001). CONCLUSION: A set of reference values for cardiac evaluation prior to chemotherapy in cancer patients without other known cardiopulmonary disease is presented. There are age-related changes in cardiac dimensions with age depending on gender, although with only limited influence on LVEF or RVEF.

Effects of filtration on right ventricular function by the gated blood pool SPECT.

OBJECTIVE: Gated blood po ol single photon emission computed tomography (GBPS) offers the possibility of obtaining additional functional information from blood pool studies, including evaluation of left and right ventricular function simultaneously. The calculation of ventricular volumes based on the identification of the endocardial surface would be influenced by the spatial resolution in the reconstructed images. This study was performed to evaluate the effect of different filters on the right ventricular function. METHODS: The normal four-dimensional (4-D) NURBS-based cardiac-torso (NCAT) phantom with known right ventricular volume and ejection fraction was generated. The SIMIND Monte Carlo program was used to create projections. The studies were reconstructed by FBP and post-processing filtration such as Butterworth, Hanning, Shepp-Logan, Metz and Wiener in different statuses (cutoff and order). Using the Cedars-Sinai QBS (quantitative blood pool SPECT) package, the ventricular functional parameters were computed. The calculated values were analyzed and compared with the normal NCAT results. RESULTS: The results implied that the calculated right ventricular end diastolic volume (RVEDV) by Butterworth filtration (cutoff frequency = 0.3) agreed more with the NCAT Phantom characteristics [relative difference percentage (RDP) = 1.2 %], while the maximum accordance in the calculation of the RV ejection fraction (EF) (RDP = 3 %) was observed by Metz filter (FWHM 20 pixel). Also, the results of this study demonstrate that the Butterworth filter provided the most stable values (cutoff frequency = 0.4-0.5) in the estimation of RVEDV (RDP = 7.5 %). The Hanning and Shepp-Logan filters produced a much larger RDP, particularly in low frequency (41.1 and 21.5 %, respectively) compared to other filters. CONCLUSIONS: This study demonstrated that the operation of different filters has a severe effect in computing right ventricular volume. The resolution recovery and Butterworth filters tend to give more comparable ventricular volumes with the actual normal NCAT value. Further evaluation using a large clinical database is underway to evaluate the optimum protocol in a clinical setting.

Interstudy repeatability of left and right ventricular volume estimations by serial-gated tomographic radionuclide angiographies using a cadmium-zinc-telluride detector gamma camera.

PURPOSE: Estimation of left ventricular ejection fraction (LVEF) with 99MTc-HSA equilibrium radionuclide angiography (RA) is frequently used for assessing cardiac function. The purpose of this study was to investigate the interstudy repeatability of left (LV) and right (RV) ventricular volume and ejection fraction estimations, using a cadmium-zinc-telluride (CZT) SPECT camera. MATERIALS AND METHODS: Forty-six patients were scanned twice, interrupted by repositioning. Each acquisition was analysed twice by two experienced technologists. Interstudy and interobserver variations were calculated as the coefficient of variation (CV) and the 95% confidence interval (CI) for limits of agreement (LOA) between each sequence of analyses for each of the two acquisitions. RESULTS: The Interstudy variations and 95% CI for LVEF, LV end systolic (LVESV) and end diastolic (LVEDV) volumes were 4.6% (-5.4 to 6.4), 9.3% (-6.90 to 5.20) and 7.0% (-13.9 to 11.1), respectively. For the right ventricle, the corresponding values were 11.9% (-9.40 to 10.8), 9.8% (-14.9 to 10.8) and 8.1% (-20.7 to 16.3). DISCUSSION: The CZT detector camera has excellent reproducibility with regard to interstudy variation when assessing LV volumes and EF. Interstudy variation is considerably higher for RV volumes and EF, indicating a lack of consistency in tracing the boarders of the right ventricle.

Gated tomographic radionuclide angiography using cadmium-zinc-telluride detector gamma camera; comparison to traditional gamma cameras.

PURPOSE: Estimation of left ventricular ejection fraction (LVEF) with equilibrium 99MTc-HSA equilibrium radionuclide angiography (MUGA) is frequently used for assessing cardiac function. The purpose of this study was to compare intra- and interobserver variation between three different gamma cameras. MATERIALS AND METHODS: Eighty-two patients, scanned in the same sequential order on the three cameras. Each acquisition was analyzed twice by two technologists. Inter- and intraobserver variations were calculated as the coefficient of variation and the 95% confidence interval for limits of agreement between each sequence of analyses for each of the three cameras. RESULTS: The lowest intraobserver variations in LVEF for the two NaI-detector cameras were 3.1% (-4.0% to 3.5%) for the planar and 3.4% (-4.2% to 4.5%) for SPECT (P ≤ 0.001-0.019), the highest result for the CZT SPECT camera was 2.6% (-2.9% to 3.1%). Similarly, interobserver variation was 4.8% (-4.8% to 6.4%) and 4.9% (-5.4% to 7.5%), respectively, for each of the NaI-detector cameras and 3.3% (-3.4% to 4.3%) for the CZT SPECT camera (P ≤ 0.001-0.008). DISCUSSION: The CZT detector camera was superior to both NaI detector cameras regarding intra- and interobserver variation. The CZT SPECT camera may identify changes in LVEF with greater certainty than its NaI detector-equipped counterparts.

Planar radionuclide angiography with a dedicated cardiac SPECT camera.

BACKGROUND: We compared a dedicated cardiac camera with a traditional system for left ventricular (LV) functional measurements using gated blood-pool imaging. METHODS: 24-frame gated planar images were obtained from 48 patients in an LAO orientation for 6M counts/view on a standard gamma camera. Immediately thereafter, 24-frame ECG-gated data were obtained for 8 minutes on a dedicated cardiac SPECT camera. The gated SPECT image volumes were iteratively reconstructed and then transferred offline. In-house software was used to reproject the images into a 24-frame gated planar format. Both the original and the reprojected gated planar datasets were analyzed using semiautomated software to determine ejection fraction (EF), ventricular volume (end diastolic volume, EDV), peak ejection rate (PER), and peak filling rate (PFR). RESULTS: The difference in EF values averaged 0.4% ± 4.4%. The correlation in EF was r ≥ 0.94 (P < .01) with a linear regression slope of 0.98. Correlation of the EDV was r ≥ 0.86 (P < .01), but the volumes from the dedicated cardiac camera were smaller (linear regression slope was 0.6). Correlation of PFR and PER were r = 0.91 and r ≥ 0.83, respectively (P < .01 for both). CONCLUSIONS: Reprojection of 24-frame gated blood-pool SPECT images is an effective means of obtaining LV functional measurements with a dedicated cardiac SPECT camera using standard 2D-planar analysis tools.

Detection of pulsation in ruptured and unruptured cerebral aneurysms by electrocardiographically gated 3-dimensional computed tomographic angiography with a 320-row area detector computed tomography and evaluation of its clinical usefulness.

BACKGROUND: In ruptured cerebral aneurysms (RCAs), identification of the rupture point of a cerebral aneurysm is useful for treatment planning. In unruptured cerebral aneurysms (URCAs), detection of the risk of aneurysmal rupture is also useful for patient management. OBJECTIVE: Electrocardiographic (ECG)-gated 3D-CT angiography was performed for patients with RCAs and URCAs using 320-row area detector CT (ADCT) to detect pulsation of the cerebral aneurysms. The clinical usefulness of this method was then evaluated. METHODS: Twelve patients had 12 RCAs, and 39 patients had 53 URCAs. A 320-row ADCT system was used to scan. ECG-gated reconstruction was then performed with the R-R interval divided into 20 phases. RESULTS: Pulsation was observed in 10 of the 12 RCAs. The bleeding site was considered to correspond to the area of pulsation. Pulsation was observed in 14 of 53 URCAs. Thirteen patients with 18 URCAs were followed. Of the 11 URCAs in which pulsation was not observed, 1 showed a change in shape. Of the 7 URCAs in which pulsation was observed, 3 showed a change in shape. URCAs in which pulsation was observed were more likely to show a change in shape (P = .082). CONCLUSION: The area of pulsation was found to correspond to the bleeding site in many RCAs. This information would be extremely useful for treatment planning. The detection of pulsation in an URCA is therefore considered to provide useful information for patient management.

The use of nuclear imaging for cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) has shown benefits in patients with end-stage heart failure, depressed left ventricular (LV) ejection fraction (< or = 35%), and prolonged QRS duration (> or = 120 ms). However, based on the conventional criteria, 20% to 40% of patients fail to respond to CRT. Studies have focused on important parameters for predicting CRT response, such as LV dyssynchrony, scar burden, LV lead position, and site of latest activation. Phase analysis allows nuclear cardiology modalities, such as gated blood-pool imaging and gated myocardial perfusion single photon emission computed tomography (GMPS), to assess LV dyssynchrony. Most importantly, GMPS with phase analysis has the potential of assessing LV dyssynchrony, scar burden, and site of late activation from a single acquisition, so that this technique may provide a one-stop shop for predicting CRT response. This article provides a summary on the role of nuclear cardiology in selecting patients for CRT, with emphasis on GMPS with phase analysis.

Evaluation of new data processing algorithms for planar gated ventriculography (MUGA).

Before implementing one of two new LVEF radionuclide gated ventriculogram (MUGA) systems, the results from 315 consecutive parallel patient studies were evaluated. Each gamma-camera acquisition was simultaneously processed by semi-automatic Medasys Pinnacle and by fully-automatic and semi-automatic Philips nuclear medicine computer systems. The Philips systems yielded LVEF results within +/- 5 LVEF percentage points of the Medasys system in fewer than half of the studies. The remaining values were higher or lower than those from the long-used Medasys system. These differences might have changed cancer patient chemotherapy clinical decisions in 54 cases (17% of studies) for one of the systems. As a result, our institution elected not to implement either new system.

[Calculation of the left ventricular ejection fraction. Comparison between 4 different instruments]. / Determinación de la fracción de eyección del ventrículo izquierdo realizada con 4 programas de cálculo distintos.

AIM: The aim of this study was to analyse the relationship between left ventricular ejection fractions (EF) obtained using four different instruments. MATERIAL AND METHODS: Eighty-five EF values were analysed. Gated acquisition was performed with the same gammacamera (SOPHA) using 99mTc-labelled red cells. Each EF was obtained using four processing systems: NXT (SOPHA), Entegra (Gems), Odyssey (Philips) and Esoft (Siemens), always working in automated mode. The paired student's t-test, Spearman correlation and Bland-Altman analysis were used to compare methods, and Deming regression was applied. RESULTS: Mean values and standard deviations for each program were: NXT: 61 +/- 9; Entegra: 60 +/- 10; Odyssey: 60 +/- 9; Esoft: 60 +/- 10. Although no significant differences were found as a whole and the values were linearly related, the methods are not interchangeable. CONCLUSIONS: The same program should be used in the follow-up of each patient, which is now easily achievable by means of the DICOM standard.

Systolic time ratio by impedance cardiography to distinguish preserved vs impaired left ventricular systolic function in heart failure.

Left ventricular ejection fraction (EF) is used to assess patients with heart failure (HF); however, frequent measurements are not cost-effective. Impedance cardiography (ICG) is a low-cost, noninvasive test that measures systolic time intervals and may be a method for detecting impaired vs intact EF. This study evaluated the relationship between EF by echocardiography or gated nuclear ventriculography and systolic time ratio (STR) by ICG in outpatients with chronic HF. A retrospective chart review identified 52 patients with EF and STR measured within 2 weeks. There was an inverse correlation between STR and EF (r=-0.54; P<.001). The area under the receiver operating characteristic curve for STR to identify reduced EF was 0.86. An EF < or =50% and STR > or =0.50 demonstrated 93% sensitivity and 85% specificity. STR was able to distinguish intact (>50%) from impaired EF (< or =50%). STR by ICG has the potential to be a reliable method to monitor ventricular function in chronic HF.

Temporal resolution of multiharmonic phase analysis of ECG-gated myocardial perfusion SPECT studies.

BACKGROUND: Multiharmonic phase analysis (MHPA) was developed to assess left-ventricular dyssynchrony from gated myocardial perfusion single-photon emission computed tomography (GSPECT) studies. This study was intended to determine the temporal resolution of MHPA. METHODS: A reference normal GSPECT study with 128 frames/cycle was simulated using NCAT, a nonuniform rational B-splines-based cardiac torso phantom. It was shifted in the time domain to insert phase delays. Realistic GSPECT studies (8 or 16 frames/cycle) were then obtained by down-sampling the reference and shifted studies. All GSPECT projections were generated with attenuation, scatter, collimator blurring, and Poisson noise. Seventeen regional phases were calculated from the GSPECT reconstructions (filtered back-projection without compensation for physical factors), using linear interpolation for the reference study, and MHPA for the realistic studies. Comparing the regional phases between the realistic studies without and with shifts determined whether MHPA could identify certain phase delays. RESULTS: When there were enough counts/pixel (>10 counts/pixel), MHPA with either 1, 2, or 3 harmonics could resolve a phase difference of 5.6 degrees , corresponding to 1/64 of the cardiac cycle. CONCLUSIONS: With clinically equivalent counts, the temporal resolution of MHPA is 1/64 of a cardiac cycle. Achieving this high temporal resolution from data with low temporal resolution demonstrates the benefit of replacing discrete points with continuous harmonic functions.

Assessment of diastolic function using 16-frame 201Tl gated myocardial perfusion SPECT: a comparative study of QGS2 and pFAST2.

OBJECTIVE: The objective of the present study is to investigate the correlations across various types of interface software for (201)Tl gated myocardial perfusion SPECT (MPS) in calculating two common diastolic function parameters (DFx), peak-filling rates (PFR), and time-to-peak filling (TTPF). METHODS: A total of 109 patients (66 men and 43 women; age 35-78 years) were studied. All patients were classified into three groups (i.e., ND, no-defect group; SD, small-defect group; LD, large-defect group) to clarify the influence of perfusion defects possibly affecting the analysis. Two kinds of available software, namely, quantitative gated SPECT (QGS2) and perfusion and functional analysis for gated SPECT (pFAST2) with cardioGRAF were used to obtain PFR and TTPF. Finally, we analyzed the correlation between DFx obtained with the two different kinds of software. RESULTS: The values of LVEF, PFR, and TTPF were assessed in all patients. In both the ND (correlation coefficients were 0.92, 0.79, and 0.99, respectively) and SD groups (correlation coefficients were 0.74, 0.88, and 0.98, respectively), a strong correlation was observed. In contrast, PFR did not show a significant correlation in the LD group. CONCLUSIONS: With the two different kinds of software, QGS2 and pFAST2, the calculated PFR was almost equal and showed good correlations in both ND and SD groups. In contrast, the numerical value varied between the two methods, and its correlation was poor in the LD group. However, TTPF showed a good correlation regardless of the presence of perfusion defects, and the values were equal. TTPF was confirmed to be a stable diastolic index across the two kinds of software, QGS2 and pFAST2, in (201)Tl gated MPS.

Localization of ventricular tachycardia exit site and subsequent contraction sequence and functional effects with bedside radionuclide angiography.

OBJECTIVES: In an effort to better understand the clinical effects of ventricular tachycardia (VT), we sought to characterize function and conduction during VT in patients. BACKGROUND: The image evaluation of VT has been limited by the lack of technical tools and its often-dramatic hemodynamic effect. Objective bedside imaging of VT-induced changes in contraction pattern, synchrony, and volumes has never been performed but could aid in the understanding of rhythm tolerance. METHODS: Equilibrium radionuclide angiography (ERNA) with phase analysis was performed during the course of 32 VT rhythms. Left ventricular ejection fraction, wall motion, synchrony, relative volumes, and exit sites were compared in 13 patients tolerant to VT (Group I) and 9 intolerant to VT (Group II). RESULTS: The ERNA VT exit site agreed with the results of electrocardiogram in 26 of 32 (81%) cases and with electrophysiologic study in 16 of 19 (84%) cases (both p < 0.05). A greater rate (157 vs. 130, p < 0.0001) accompanied VT intolerance, but the exit site in 4 patients with multiple VT patterns also appeared important to tolerance. Left ventricular ejection fraction, similar in both groups in sinus rhythm, decreased with VT in Groups I (28 to 19) and II (31 to 15), both p<0.03, with a greater relative decrease in LV ejection fraction, LV stroke volume (65% vs. 45%, p < 0.01), cardiac output (30% vs. 2%), and LV end-diastolic volume (36% vs. 27%, both p < 0.001), in Group II. The standard deviation of LV phase angle (Ø) was the only parameter which differed between Groups I and II (35 vs. 45, p < 0.01) in sinus rhythm. With VT, wall motion deteriorated generally, but with greater standard deviation LVØ, p < 0.05, and dyssynchrony in Group II. Ventricular tachycardia induced 14 functional aneurysms, often adjacent to VT exit sites. CONCLUSIONS: A challenging bedside imaging protocol evaluated VT-induced changes. We found that the use of ERNA demonstrated function, synchrony, and volume differences between tolerant and intolerant VT rhythms, delineated the contraction pattern, and localized exit sites.

Reconstruction of dynamic gated cardiac SPECT.

In this paper we propose an image reconstruction procedure which aims to unify gated single photon emission computed tomography (SPECT) and dynamic SPECT into a single method. We divide the cardiac cycle into a number of gate intervals as in gated SPECT, but treat the tracer distribution for each gate as a time-varying signal. By using both dynamic and motion-compensated temporal regularization, our reconstruction procedure will produce an image sequence that shows both cardiac motion and time-varying tracer distribution simultaneously. To demonstrate the proposed reconstruction method, we simulated gated cardiac perfusion imaging using the gated mathematical cardiac-torso (gMCAT) phantom with Tc99m-Teboroxime as the imaging agent. Our results show that the proposed method can produce more accurate reconstruction of gated dynamic images than independent reconstruction of individual gate frames with spatial smoothness alone. In particular, our results show that the former could improve the contrast to noise ratio of a simulated perfusion defect by as much as 100% when compared to the latter.