Interest of the evaluation of the LV area in the evaluation of the TID in MPS through IQ SPECT
Authors: Rabines-Juarez AO , Camarero Salazar A , Ribeles Segura MJ , Blanco Saiz MI , Rudic Chipe NA , Alomar Casanovas A , Saura Lopez I , Goni Girones E 
Published: July 2021

Abstract

Funding Acknowledgements
Type of funding sources: None.

Objectives
To the determine the value as ischemic indicator of measurement of left ventricular areas under stress and rest conditions in the evaluation of the transient ischemic dilation.

Methodology
This quantitative, observational and cross sectional study included patient undergoing myocardial perfusion SPECT/CT (MPS).

Protocol
2-day exercise stress/rest, radiotracers tetrofosmin/MIBI Tc-99m, IQ- SPECT (smartzoom collimators, 17 slices, 20-sec/slice), with/without CT-based attenuation correction (NC and AC, respectively) and processing with Cedars-Sinai QPS software.
A descriptive statistical analysis was performed to evaluate patient conditions; MPS results, left ventricular parameters (volume of cavity and area), transient dilation and area dilation ratios.
An agreement analysis according by Blend-Altman plots and correlation analysis was realized between TID y LV areas ratios.
An univariate analysis by chi square test was used to determine whether there is a statistically significant difference between the frequecies of results of precited factors and TID

Results
99 patiens with MPS were included. They were categorized in two groups as 87.87% with normal TID (values : 0.9-1.26) and 12.13% with TID &gt; 1.25 .
The mean age was 62,11 ± 10.29 years old and male were 70,1%. The prevalence of clinical conditions were 62.1% of arterial hypertension , 19.5% of type-2 diabetes mellitus and 72.4% dyslipidemia.
The prevalence of cardiac disease were 60.9% ischemic cardiac disease, 17.2% cardiac rhythm alterations, 27.6% of cardiac valve disease, 13.8% myocardial hypertrophy and 4.6% dilated cardiomyopathy. There were no statistically significant differences of precited parameters between the two groups.
There are 9.19% mild and 2.29% moderate ischemics MPS results in the normal TID group and 36.36% mild ischemic MPS result in the TID &gt; 1.25 group. (p &lt; 0.05)
In the normal TID group the stress /rest area ratios were 1.016 ± 0.13 for NC studies and 1.016 ± 0.12 for AC studies (p &gt; 0.05). In the TID &gt; 1.25 group the stress /rest area ratios were 1.13 ± 0.05 for NC studies and 1.12 ± 0.08 for AC studies (p &gt; 0.05) The normal values limits 1.016 ± 0.26 for NC studies and 1.016 ± 0.24 for AC studies.
The agreement using the Bland-Altman method showed that the mean difference between TID and stress/rest ratios by NC and AC studies was 0.02 ± 0.08 (-0.13 to 0.18; 95% confidence interval) and 4.04% within the 95% confidence interval.
Pearson correlation coefficient obtained between TID and area ratios was 0.69 in the NC studies and 0.91 in AC studies.
This is consistent with the recommendations for studies with detectors SMARTZOOM would advise the use of AC determinations.

Conclusions
The presence of left ventricular areas within normal values in patients with TID visualized in MPS suggests the existence of endocardial ischemia and no ventricular dilation. The joint assessment of these parameters adds value in those situations.