Scintimetric Characterization of Left Ventricular Diastolic Dysfunction by Phase Image Analysis in Gated Thallium SPECT Scan

Aim: The Scintimetric characterization principle is applied to the identification and quantification of presence of diastolic dysfunction using the gated thallium SPECT scans. The assessment and differentiation of Left Ventricular Diastolic Dysfunction is critical in the treatment of heart failure patients. Diastolic dysfunction is currently inferred primarily from E and A wave changes in m-mode echocardiographic changes at the mitral orifice. In the gated myocardial perfusion imaging from the time volume curve the Peak Flow Rate and Time to Peak Flow rate are derived and assessed for the presence and extent of diastolic dysfunction. All of these parameters represent changes in the left ventricular muscle mass caused by the underlying diastolic dysfunction.This study aims to highlight the diagnosis of Left Ventricular Diastolic Dysfunction for the first time using visual Phase image analysis in Gated Thallium SPECT Scan. The presence of inhomogeneous, irregular, and insufficient tracer accumulation in diastolic phase images compared to normal and homogeneous tracer distribution in systolic phase images is thought to indicate diastolic dysfunction. It also thrives to quantify the changes observed by calculating the S/D ratio by dividing the Systolic Counts by the diastolic counts obtained from the raw phase images. It is correlated with echocardiographic stages of the Diastolic Dysfunction.

Materials and Methods: This study consists of 75 Males in the age group of 28 to 63 years with mean age of 47.9 +/- 7.8 years and 25 Females in the age range of 32 to 55 years with mean age of 49 +/- 6.8 years. After exercising the patients on a bicycle ergometer using Bruce Protocol 2 mCi of Thallum-201 was injected intravenously Gated SPECT MPI were acquired using Siemens Dual Head E-Cam Gamma Camera. The analysis was done using GATED SPECT PERFUSION ANALYSIS Protocol. The S/D ratio was calculated using the region ratio count protocol in the ICON software.

Results: The discordance between the Diastolic and systolic images were found in 98/100 (98%)- Image1,2. The Echocardiographic evidence of Diastolic dysfunction as classified into Grade II and grade III using E / A ratio analysis was found in 87/100 (87%). The diabetes was seen in 16/100 (16%) and Hypertension was encountered in 63/100 (63%). The S/D ratio was 1.27 +/- 0.32 in Grade IILVDD and 1.68 +/- 0.03 Grade III LVDD.

Conclusion: Finally, the utility of direct visual individual phase image analysis in the detection of Left Ventricular Diastolic Dysfunction is highlighted for the first time. The Scintimetric Characterization of the same with the help of S/D ratio has been shown to be different between stage II and stage III LVDD.