International Conference of Nuclear Cardiology and CT

Dra Aloha Meave, Dr. Erick Alexanderson, INCICH

Berlin 0513

La reunión se desarrolló desde un contexto multimodal, lo que denota el enfoque con el que se estudian los pacientes hoy en día al aplicar los métodos de Imagen Cardiovascular.

En Tomografía cardiaco se trataron temas básicos sobre cómo realizar el procedimiento, la revisión de los diferentes protocolos que existen y la importancia de la optimización de la dosis de radiación.

En Cardiología nuclear se discutió el tema de nuevas cámaras SPECT más rápidas y con mejor resolución espacial. La posibilidad de la cuantificación de flujo con SPECT y la utilidad del SPECT en el pronóstico del paciente isquémico y con Insuficiencia Cardiaca.

En PET el tema se centró en los nuevos trazadores (18 F-flurpiridaz) para el estudio del paciente con Insuficiencia Cardiaca y en el estudio de receptores adrenérgico y marcadores de inflamación vascular y placa coronaria (Fluoruro de Sodio). Se discutió también la importancia clínica de la Cuantificación del flujo miocárdico.

Respecto a equipos híbridos se mostró la importancia y utilidad de la fusión de las imágenes de PET y angiotomografía coronaria

Se revisaron los criterios apropiados de utilización de los diferentes métodos.

Se realizaron sesiones de lectura con los expertos y un dinámico Jeopardy de lectura con casos multimodales.

El Instituto participó con los siguientes trabajos de investigación:

Trabajo 1.

Left ventricular geometry indexes evaluated by preoperative gated-SPECT in severe CAD and their correlation to hospitalization post CABG: a five year follow up.
M. Jimenez-Santos1, LE. Rodriguez-Castellanos1, S. Hernandez-Sandoval1, LE. Juarez-Orozco2, EA. Penarrieta-Daher1, LV. Araujo-Torres1, CA. Guizar-Sanchez1, E. Alexanderson Rosas1 - (1) Instituto Nacional de Cardiología "Ignacio Chávez", Mexico City, Mexico (2) Unidad PET/CT Ciclotrón UNAM, Mexico city, Mexico

Left ventricular geometry indexes approaching to sphericity have been studied with gated-SPECT in hospital heart failure patients. In the other hand, these indexes have also been used as measures of ventricular remodeling and myocardial viability.

In this longitudinal retrospective study 60 patients were included from 2005 to 2007 and were followed for 5 years.

We correlated abnormal pre-procedure left ventricular geometry indexes (shape index (SI), eccentricity index (EI) as well as end-diastolic (EDV) and end-systolic left ventricular volumes (ESV) ) by gated-SPECT in patients with severe CAD to number of hospitalization rates due to heart failure, heart failure progression or posoperative death in a 5 year follow-up CABG.

Results: The hospitalization rate was 16%; SI at rest was 0.717 vs. 0.581 (p=0.0001) and at stress was 0.544 vs. 0.637 (p=0.021) (hospitalization); EI was not significantly different in all the cases. The rate of cardiac death was 23%; there were non statistically significant differences of the evaluated parameters between the groups. The rest SI was different, in NYHA I was 0.542; NYHA II was 0.637 and NYHA III 0.81 with P value=0.0001; the stress SI was not statistically different between the groups.

Conclusion: in this study we demonstrate that the SI at rest was statistically different between the NYHA groups for MACE prognosis and hospitalization. Preoperative gated-SPECT can discriminate patientes with higher probability of developing heart failure, although it was not observed in the other values evaluated in this study.

Trabajo 2.

Left ventricle ejection fraction: correlation with infarct size and myocardial perfusion reserve post-MI
RHJA. Slart1, LE. Juarez-Orozco2, E. Alexanderson Rosas3, RA. Tio1, RA. Dierckx1, EA. Penarrieta-Daher3, J. Glauche1, LV. Torres-Araujo3 - (1) University of Groningen, University Medical Center Groningen, Groningen, Netherlands (2) Unidad PET/CT Ciclotrón UNAM, Mexico city, Mexico (3) Instituto Nacional de Cardiología "Ignacio Chávez", Mexico City, Mexico

Introduction: Left ventricular function after myocardial infarction is considered to be determined by the size of the infarction and residual function of the spared myocardium. Myocardial perfusion reserve assessed by 13N-ammonia PET has been shown to be a strong predictor in patients with ischemic heart failure. Unknown is the value of MPR in the spared myocardium in relation with infarct size and LVEF. In the present study, the interrelationship between MPR, LVEF and infarct size was acquainted.

Methods: In this study, 102 patients with a prior history of myocardial infarction were included. All underwent rest – dypiridamole stress 13N-ammonia and gated FDG PET for evaluation of myocardial perfusion reserve and viability. FDG polar maps were used to determine the size of the infarction. The LVEF was obtained by gated FDG PET or another available method within 3 months of the PET scan. The segmental MPR was obtained by dividing stress and rest myocardial perfusion in the spared myocardium.

Results: Mean age of the subjects was 69 ± 12 years (men 78%), global MPR was 1.65 ± 0.51. Mean LVEF was 36 ± 9.8%, mean infarct size 23.6 ± 14.6%. Fifty patients had dyslipidemia, 41 hypertension, 13 diabetes, 45 were smokers, and 35 a positive family history for cardiovascular disease. Linear regression model was applied for the analysis considering the LVEF as an independent variable. All risk factors, infarct size and MPR were entered as variable. The infarct size (P <0.001) and MPR (P = 0.008) reached statistical significance. Of all risk factors only diabetes mellitus (P = 0.030) showed a significant correlation with LVEF.

Conclusions: In patients with a prior history of myocardial infarction, LVEF is not just related to infarct size but also to MPR in the spared myocardium.

Trabajo 3.

Diastolic function and ventricular synchrony in low cardiovascular risk population: An assessment with 13N-Ammonia PET/CT scanning.
E. Alexanderson Rosas1, LE. Juarez-Orozco2, RHJA. Slart3, EA. Penarrieta-Daher1, LV. Torres-Araujo1, RA. Tio3, A. Meave1, RA. Dierckx3 - (1) Instituto Nacional de Cardiología "Ignacio Chávez", Mexico City, Mexico (2) Unidad PET/CT Ciclotrón UNAM, Mexico city, Mexico (3) University of Groningen, University Medical Center Groningen, Groningen, Netherlands

Introduction: Cardiovascular PET/CT scanning has developed, beyond doubt as an important adjuvant for diagnostic, prognostic and therapeutic evaluation in cardiac disease. Nevertheless, little is known about the significance and potential utility of the diastolic function and phase synchrony parameters obtained by PET/CT reconstruction algorithms due to lack of normal and low risk population studies.

Methods: We performed and analyzed eighteen 13N-Ammonia 2-phase perfusion PET/CT scans with a "list mode" acquisition for static, dynamic and gated images in low cardiovascular risk patients according to the cardiovascular risk Framingham score. Furthermore we obtained the determination of peak filling rate (PFR) and time to peak filling (TTPF) for diastolic function evaluation; histogram bandwidth (HB), standard deviation (SD) and entropy (E) were obtained for phase synchrony assessment. Resting shape index (SI) and left ventricle ejection fraction (LVEF) was included from the gated acquisition.

Results: We included 6 male and 12 female patients with a mean age of 56±10 years. Findings are depicted in Table 1.

Conclusions: PET/CT perfusion scans provide quantitative assessment of diastolic function and ventricle synchrony. We found that diastolic function parameters are close to the ones reported in SPECT scanning but not the synchrony ones, this could be related to the automatic border delimitation in the basal portion of the heart. Further research for normal measurements is needed.

 

Table 1. Descriptive Statistics n=18
Descriptive Statistics (Mean +/- Standard Deviation) n=18
  Gated Synchrony Diastolic Function
Phase LVEF SI HB SD E PFR TTPF
Stress 69 +/- 7.9 0.58 +/- 0.1 133.6 +/- 68.9 42.3 +/- 13.9 39.1 +/- 7.4 2.55 +/- 0.3 194 +/- 38
Rest 66.3 +/- 7.6 0.55 +/- 0.1 147.6 +/- 56.3 44 +/- 14.4 22.7 +/- 23.5 2.55 +/- 0.3 176.5 +/- 36.5
LVEF: Left Ventricular Ejection Fraction, SI: Shape Index, HB: Histogram Bandwidth, SD: Standard Deviation, E: Entropy, PFR: Peak Filling Rate, TTPF: Time to Peak Filling.

Trabajo 4.

Correlation between perfusion abnormalities and myocardial blood flow using 13N-ammonia PET/CT in patients with CAD
E. Alexanderson Rosas1, LV. Torres-Araujo1, EA. Penarrieta-Daher1, LE. Juarez-Orozco1, S. Hernandez-Sandoval1, CA. Guizar-Sanchez1, A. Meave-Gonzalez1, M. Jimenez-Santos1, MM. Martinez-Aguilar1 - (1) Instituto Nacional de Cardiología "Ignacio Chávez", Mexico City, Mexico

Introduction: PET/CT provides anatomical information of the coronary arteries, along with objective evidence of its functional impact. New software provide an automated perfusion scoring of the 17 left ventricular segments, calculating perfusion scores: Summed Rest Score (SRS), Summed Stress Score (SSS), Summed Differential Score (SDS), and the quantification of Myocardial Blood Flow (MBF), Coronary Flow Reserve (CFR) and the quantification of Total Perfusion Defect (TPD).

Methods: We studied 30 patients with known CAD determined by CCTA, who underwent a 13N-Ammonia Gated PET study. The patients were divided, by the severity of ischemia based on visual interpretation of the 13N-Ammonia PET perfusion images, into three groups: mild, moderate and severe ischemia. Ten patients were included in each group. The SRS, SSS, SDS, rest and stress TPD (rTPD and sTPD), rest and stress MBF (rMBF and sMBF) and CFR were calculated, using the CSI Software. The one factor ANOVA test was used to determine if there is a significant correlation in any of the above mentioned values proportional to the severity of the ischemia.

Results: Table 1.

Conclusions: We found an inversely significant proportional relation between the degree of ischemia and the absolute MBF values. Coronary flow reserve was decreased in patients with high score of SDS and sTPD. sTPD can help to identify a patient with low CFR in the absence of flow evaluation.

 

Table 1. Comparison of PET/CT Parameters
PET Parameters Mild Ischemia (mean +/- SD) Moderate Ischemia (mean +/- SD) Severe Ischemia (mean +/- SD) p
SRS 1 +/- 1.55 2.1 +/- 2.47 24.1 +/- 11.12 <0.001
SSS 5.7 +/- 1.1 10.9 +/- 1.45 38.9 +/- 12.05 <0.001
SDS 4.7 +/- 2.15 8.8 +/- 2.89 14.8 +/- 11.75 0.01
rTPD 5.11 +/- 4.01 8.43 +/- 7.31 36.5 +/- 18.38 0.0007
sTPD 9.78 +/- 0.05 15 +/- 6.26 43.25 +/- 16.01 0.0004
rMBF 0.85 +/- 0.25 0.68 +/- 0.13 0.74 +/- 0.33 0.387
sMBF 2.43 +/- 0.88 1.84 +/- 0.40 0.95 +/- 0.25 <0.001
CFR 2.90 +/- 0.74 2.73 +/- 0.57 1.66 +/- 0.49 <0.001
PET: Positron Emission Tomography, SRS: Summed Rest Score, SSS: Summed Stress Score, SDS: Summed Difference Score, rTPD: Rest Total Perfusion Defect, sTPD: Stress Total Perfusion Defect, rMBF: Rest Myocardial Blood Flow, sMBF: Stress Myocardial Blood Flow, CFR: Coronary Flow Reserve.

Trabajo 5.

Prognostic value of gated-SPECT left ventricular shape index in post-MI patients
E. Alexanderson Rosas1, C. Sierra-Fernandez1, EA. Penarrieta-Daher1, LE. Juarez-Orozco1, LV. Torres-Araujo1, A. Jordan-Rios1, S. Hernandez-Sandoval1, CA. Guizar-Sanchez1, A. Meave1, M. Jimenez-Santos1 - (1) Instituto Nacional de Cardiología "Ignacio Chávez", Mexico City, Mexico

Ischemic heart disease is one of the major causes of mortality and morbidity worldwide. The objective of this study is to determine the prognostic value of Telesystolic Left Ventricular Shape Index (TS LVSI) in post-MI patients.

Methods: In this historic cohort study 51 post-MI patients (46 males and 5 females, mean of age 62 years old) with 5-year follow up were included. One-day rest-stress gated SPECT sestamibi protocol was performed in all patients 6 to 12 months post-MI. CSI Cedar-Sinai software was used to calculate all the gating and perfusion parameters as well as TS LVSI.  SPSS Mac v.20 was used for statistical analysis.

Results: The prognostic analysis demonstrated a global mortality of 7.8% when TS LVSI was ≥0.54, while there were no mortality cases at a TS LVSI ≤ 0.53 (p < 0.01). Assessing NYHA Class deterioration, 21.6% of TS LVSI ≥0.54 patients had a decrease in functional class when compared with 3.9% of those who had a TS LVSI ≤ 0.53 (p <0.001). Overall, we found a mortality RR of 19 (CI 95% 1.8-33.4 p=0.04) and a NYHA Class deterioration RR of 12.03 (CI 95% 3.0-48.09 p <0.01) for a TS LVSI ≥0.54. Table 1 compares TS LVSI with LVEF, SRS, SSS and SDS.

Conclusion: TS LVSI is a good prognostic parameter and allows better determination of patients with risk of cardiac death or NYHA class deterioration than LVEF, degree of ischemia and MI extension, when taking 0.54 as a cutoff value. These risks increase proportionally with this index, reaching a mortality of 100% when ≥ than 0.70.

 

Table 1. G-SPECT parameters comparison
G-SPECT Parameter Deceased patients Surviving patients p NYHA I NYHA deterioration p
TS LVSI 0.68 +/- 0.06 0.48 +/- 0.08 <0.01 0.47 +/- 0.08 0.60 +/- 0.07 < 0.01
LVEF 40.5 +/- 16.5 54.5 +/- 13.5 0.05 57.4 +/- 11.9 41.8 +/- 13.8 < 0.01
SRS 17.2 +/- 6.5 13.1 +/- 8.2 0.05 12.1 +/- 7.9 17.2 +/- 7.9 0.06
SSS 19.7 +/- 6.2 16.9 +/- 9 0.54 15.6 +/- 8.6 21.4 +/- 8.2 0.04
SDS 2.5 +/- 2 3.9 +/- 2.4 0.41 3.7 +/- 3 4.2 +/- 4.0 0.61
G-SPECT: Gated-Single Photon Emission Computed Tomography, TS LVSI: Telesystolic Left Ventricular Shape Index, SRS: Summed Rest Score, SSS: Summed Stress Score, SDS: Summed Difference Score

 

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