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ORIGINAL ARTICLE
Year : 2010  |  Volume : 25  |  Issue : 4  |  Page : 156-159  

Do reconstruction filters really effect the volume and ejection fraction calculation with 99m Tc-sestamibi-gated myocardial SPECT?


Department of Nuclear Medicine, SGPGIMS, Lucknow, India

Date of Web Publication23-Mar-2011

Correspondence Address:
Subhash Chand Kheruka
Department of Nuclear Medicine, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Rae Bareli Road, Lucknow-226 014
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-3919.78251

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   Abstract 

Background : ECG -gated myocardial perfusion imaging is a sensitive test for diagnosis of ischemia as well as scarred myocardium. It provides additional information on global and regional myocardial contractile function. A number of methods are available to calculate left ventricular volumes and ejection fractions, which depends on various technical and patients specific factor. Objective: This study was carried out to measure effect of reconstruction filter in calculations of left ventricularend diastolic volume (EDV) and end systolic volume (ESV) and left ventricular ejection fraction (LVEF) from 99mTc-sestamibi myocardial perfusion imaging. Materials and Methods: 99mTc-sestamibi-gated SPECT myocardial perfusion imaging was performed in 90 patients. Studies were reconstructed with Butterworth and Metz filters. Results: Mean ejection fraction with Butterworth and Metz filter are 64.3 and 64.2, respectively. Mean EDV is for Butterworth and Metz filters are 77.3 and 78.5 ml, respectively. While ESV was 36.49 and 36.63 ml, stroke volume calculated was 41.54 and 42 ml for Butterworth and Metz filters,respectively. Pearsons's correlation coefficients between results calculated with Metz and Butterworth filters were 0.994 for ESV, 0.996 for EDV, 0.966 for LVEF and 0.925 for SV. Student 't' test was applied on the data and no significant difference was noted between parameter estimated by Butterworth or Metz filter. Conclusion: This study shows that difference of filter application has no significant effect in computing left ventricular function parameters.

Keywords: Butterworth, ejection fraction, Metz, Myocardial perfusion imaging, reconstruction filter


How to cite this article:
Ora M, Kheruka SC, Barai S, Gambhir S. Do reconstruction filters really effect the volume and ejection fraction calculation with 99m Tc-sestamibi-gated myocardial SPECT?. Indian J Nucl Med 2010;25:156-9

How to cite this URL:
Ora M, Kheruka SC, Barai S, Gambhir S. Do reconstruction filters really effect the volume and ejection fraction calculation with 99m Tc-sestamibi-gated myocardial SPECT?. Indian J Nucl Med [serial online] 2010 [cited 2019 Sep 16];25:156-9. Available from: http://www.ijnm.in/text.asp?2010/25/4/156/78251


   Introduction Top


Myocardial perfusion imaging is a sensitive test for diagnosis of ischemia as well as scarred myocardium. Electrocardiography (ECG)-gated imaging provides additional information on global and regional myocardial contractile function, [1] and allows the calculation of left ventricular end diastolic volume (EDV), end systolic volume (ESV), stroke volume (SV) and ejection fraction (LVEF). [2] This functional information gives additional prognostic information

A number of methods are available to calculate left-ventricular volumes and ejection fractions. [3],[4] Various volumes and ejection fraction calculated depended on software used, [5] calculation method used, acquisition parameter such as number of frames, [6] zoom factor, [7] filter used for image reconstruction. [8],[9] The accuracy of results may also be affected by patient-specific factors such as cardiac volume, patient size and perfusion defect size. [10]

It has been emphasized that the effect of changing filter may invalidate the clinical parameter. This study was carried out to measure effect of reconstruction filter in calculations of left-ventricular EDV and ESV and LVEF from 99m Tc-sestamibi myocardial perfusion imaging.


   Materials and Methods Top


Patients 99m Tc-sestamibi-gated SPECT myocardial perfusion imaging was performed in 90 patients.

Gated SPECT acquisition

Myocardial gated SPECT was carried out 1 hour after intravenous injection of 400 MBq 99m Tc-sestamibi. SPECT acquisition was carried out on a dual-head large field of view γ-camera (DXTXL SMV). Sixty-four projections (32 per head) were obtained in 64×64 matrices using a step and shoot acquisition over a 180º arc from right anterior oblique to left posterior oblique position. Acquisition zoom was 1.33, giving a pixel size of 6.7 mm. All studies were acquired with 16 frames per cardiac cycle using an R-wave trigger and a 40% acceptance window.

Gated SPECT data processing

Studies were processed on a Xeleris version 1.330. Images were pre-filtered, and then reconstructed by filtered back-projection with a ramp filter. Two filters recommended by the manufacturer for reconstruction of gated SPECT studies, Butterworth order 10, cut-off frequency 0.394 cycles/pixel and Metz order 3.25, full-width half-maximum 2.35 mm, were compared. The former is a low pass filter, while the latter is an edge-enhancement filter. Both these types of filter have been shown to be effective in reconstructing SPECT studies. Myocardial EDV (ml) and ESV (ml), SV (ml) and LVEF (%) were determined using a commercial semi-automatic gated SPECT processing software, Emory toolbox. Processing was performed by a single operator for each study using the two filters concurrently

Calculations

Statistical analysis was performed with the SPSS program version 13 for Windows. The Spearman rank correlation coefficient was used to test for correlations. The individual differences for each patient between filtering with Metz and Butterworth filters were calculated, and statistical differences were tested for using a paired t-test.


   Result Top


The ESV and EDV, SV and LVEF are shown in [Table 1]. Mean ejection fraction with Butterworth and Metz filter are 64.3 and 64.2. Mean EDV is for Butterworth and Metz filters are 77.3 and 78.5 ml. While ESV was 36.49 and 36.63 ml, SV calculated was 41.54 and 42 ml for Butterworth and Metz filters, respectively. Pearsons's correlation coefficients between results calculated with Metz and Butterworth filters were 0.994 for ESV, 0.996 for EDV, 0.966 for LVEF and 0.925 for SV [Figure 1],[Figure 2],[Figure 3].
Table 1: Different cardiac volume measured by Butterworth and Metz filter

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Figure 1: Bar diagram representing different parameter measured from Butterworth and Metz filter

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Figure 2: Linear bar diagram to show correlation of EF, EDV, ESV and SV measured by Butterworth and Metz filter

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Figure 3: Scatter diagram showing correlation between ejection fraction measured from both filters

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Student 't' test was applied on the data and no significant difference was noted between parameter estimated by Butterworth or Metz filter [Table 2].
Table 2: Result of Student 't' test

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   Discussion Top


During processing of ECG gated Myocardiac perfusion imaging quantification starts with the detection of the LV endocardial and epicardial boundaries. Most algorithms first estimate the location of the midmyocardium, which corresponds to the maximal myocardial count. From the midmyocardial points, endocardial and epicardial boundaries can be extracted either by using a fixed number of SDs of gaussian fitting to the myocardial count profile [11],[12] or using a predefined count threshold based on the phantom data. [13] Once the definitions of the endocardial and epicardial edges are achieved, LV volume is calculated by multiplying the number of pixels within the LV cavity with the size of a pixel. LV volume can be generated for each of the frames in the cardiac cycle. The largest volume and the smallest volume represent the EDV and the ESV, respectively. LVEF is derived from the volumes using the formula (EDV - ESV)/EDV ×100.

As endocardial edge is found from the maximum slope of the profile between the cardiac center and the wall center, [14] which would be expected to vary with filter, and to give a thicker wall measurement with a smoother filter. [15] A thicker wall will lead to a smaller cardiac volume, and so volumes were expected to be smaller with the smoother Butterworth filter is comparison to sharper Metz filter. But we were not able to demonstrate this difference is our study. We expected that the difference in wall thickness would be comparable in both end-diastole and end-systole, so the SV would not be affected by the filter that was found true later in study. As both EDV and ESV are not affected by application of different filter so EF is also same.

The result of this study is in contrast with that of observed by Vakhtangandze et al, [16] and Wright A [8] et al, which have shown that smoother reconstruction filters lead to lower volumes and higher ejection fractions. Although excellent correlation was noted between the filters but the difference was significant statistically. Number of patients was 30 and 40 in these studies. Mean difference of ejection fraction was -3.5 ± 0.9 (Metz and Butterworth) and 2.55 ± 3.10% (Butterworth and Hann filter). This difference may be statistically significant but unlikely to be clinically significant.

LVEF is a has been established as an indicator of prognosis after myocardial infarction [17] and heart failure. [18] ESV is the most sensitive parameter in determining improvement in left ventricular function after revascularization. [19] Left ventricular volumes can be measured by radionuclide ventriculography.[20] White et al, also focusing on patients with recent myocardial infarction demonstrated that besides LVEF, left ventricular volumes are important in the prediction of survival. Progressive increments of 25 ml in ESV augmented the relative risk of cardiac death in an exponential fashion: as compared to patients with a normal ESV (30-55 ml), patients with an ESV of 75 ml and 125 ml had a 2.5-fold and a 5-fold higher relative risk of cardiac death, respectively. [21]

Gated cardiac scan has one additional advantage of increasing specificity of myocardiac perfusion imaging. As perfusion-scan fixed defects may result from soft tissue attenuation, decreasing test specificity for coronary disease and myocardial infarction (MI). Gated 99m Tc-sestamibi SPECT may help differentiate MI from artifact since fixed defects with decreased function (wall motion and thickening) probably represent MI, whereas attenuation artifacts either have normal function or at least do not demonstrate markedly reduced function. [22]


   Conclusion Top


There were no statistically significant mean differences in EDV, ESV, LVEF and SV measured using Butterworth and Metz filters. The differences found in our study are dissimilar to those from previous studies comparing reconstruction with different filters. [16],[17] The correlations between two filters were good for all functional parameter.

These results show that difference of filter application has no major effect on left ventricular function parameter.

 
   References Top

1.Anagnostopoulos C, Harbinson M, Kelion A, Kundley K, Loong CY, Notghi A, et al. Procedure guidelines for radionuclide myocardial perfusion imaging. Nucl Med Commun 2003;24:1105-19.  Back to cited text no. 1
    
2.Jessup M, Brozena S. Heart failure. New Engl J Med 2003;348:2007-18.   Back to cited text no. 2
    
3.Germano G, Kiat H, Kavanagh PB, Moriel M, Mazzanti M, Su HT, et al. Automatic quantification of ejection fraction from gated myocardial perfusion SPECT. J Nucl Med 1995;36:2138-47.  Back to cited text no. 3
    
4.Faber TL, Cooke CD, Folks RD, Vansant JP, Nichols KJ, DePuey EG, et al. Left ventricular function and perfusion from gated SPECT perfusion images: An integrated method. J Nucl Med 1999;40:650-9.  Back to cited text no. 4
    
5.Kakhki VR, Zakavi SR, Sadeghi R. Comparison of two software in gated myocardial perfusion single photon emission tomography, for the measurement of left ventricular volumes and ejection fraction, in patients with and without perfusion defects Hell J Nucl Med 2007;10:19-23.  Back to cited text no. 5
    
6.Navare SM, Wackers FJ, Liu YH. Comparison of 16-frame and 8-frame gated SPET imaging for determination of left ventricular volumes and ejection fraction. Eur J Nucl Med 2003;30:1330-7.  Back to cited text no. 6
    
7.Véra P, Manrique A, Pontvianne V, Hitzel A, Koning R, Cribier A. Thallium-gated SPECT in patients with major myocardial infarction: Effect of filtering and zooming in comparison with equilibrium radionuclide imaging and left ventriculography. J Nucl Med 1999;40:513-21.  Back to cited text no. 7
    
8.Wright GA, McDade M, Martin W, Hutton I. Quantitative gated SPECT: The effect of reconstruction filter on calculated left ventricular ejection fractions and volumes. Phys Med Biol 2002;47:N99-105  Back to cited text no. 8
    
9.Vera P, Manrique A, Pontvianne V, Hitzel A, Koning R, Cribier A. Thallium gated SPECT in patients with major myocardial infarction: Effect of filtering and zooming in comparison with equilibrium radionuclide imaging and left ventriculography. J Nucl Med 1999;40:513-21.  Back to cited text no. 9
    
10.Pai M, Yang YJ, Im KC, Hong IK, Yun SC, Kang DH, et al. Factors affecting accuracy of ventricular volume and ejection fraction measured by gated tl-201 myocardial perfusion single photon emission computed tomography. Int J Cardiovasc Imaging 2006;22:671-81.   Back to cited text no. 10
    
11.Germano G, Kiat H, Kavanagh PB, Moriel M, Mazzanti M, Su HT, et al. Automatic quantification of ejection fraction from gated myocardial perfusion SPECT. J Nucl Med 1995;36:2138-47.  Back to cited text no. 11
    
12.Germano G, Erel J, Lewin H, Kavanagh PB, Berman DS. Automatic quantitation of regional myocardial wall motion and thickening from gated technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography. J Am Coll Cardiol 1997;30:1360-7.  Back to cited text no. 12
    
13.DePuey EG, Nichols K, Dobrinsky C. Left ventricular ejection fraction assessed from technetium-99m-sestamibi SPECT. J Nucl Med 1993;34:1871-6.  Back to cited text no. 13
    
14.Maunoury C, Chen CC, Chua KB, Thompson CJ. Quantification of left ventricular function with Thallium-201 and Technetium-99m-Sestamibi myocardial gated SPECT. J Nucl Med 1997;38:958-61.  Back to cited text no. 14
    
15.Hall DO, Zananiri FV. A phantom study of the effects of acquisition and reconstruction parameters on measured myocardial wall thickness and cavity size. Eur J Nucl Med 2002;29:S355.  Back to cited text no. 15
    
16.Vakhtangandze T, Hall DO, Zananiri FV, Rees MR. The effect of Butterworth and Metz reconstruction filters on volume and ejection fraction calculations with 99 Tc m gated myocardial SPECT. Br J Radiol 2005;78:733-6.  Back to cited text no. 16
    
17.Shah PK, Pichler M, Berman DS, Singh BN, Swan HJ. Left ventricular ejection fraction determined by radionuclide ventriculography in early stages of first transmural myocardial infarction. Relation to short-term prognosis. Am J Cardiol 1980;45:542-6.  Back to cited text no. 17
    
18.Goldman S, Johnson G, Cohn JN, Cintron G, Smith R, Francis G. Prognostic significance of serial changes in left ventricular ejection fraction in patients with congestive heart failure. Circulation 1993;87:17-23.  Back to cited text no. 18
    
19.Bax JJ, Arend FL, Schinkel AF, Boersma E, Elhendy A, Rizzello V, et al. Effective left ventricular remodeling does not allow viable myocardium to improve in ejection fraction after revascularization and is associated with worse long term prognosis. Circulation 2004;110:II18-22.  Back to cited text no. 19
    
20.Thorley PJ, Sheard KL, Rees MR. A comparison of methods for estimating left-ventricular volumes from radionuclide ventriculography. Physiol Meas 1993;14:23-32.  Back to cited text no. 20
    
21.White HD, Norris RM, Brown MA, Brandt PW, Whitlock RM, Wild CJ. Left ventricular end-systolic volume as the major determinant of survival after recovery from myocardial infarction. Circulation 1987;76:44-51.  Back to cited text no. 21
    
22.DePuey EG, Rozanski A. Using gated technetium-99m-sestamibi SPECT to characterize fixed myocardial defects as infarct or artifact. J Nucl Med 1995;36:952-5.  Back to cited text no. 22
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2]



 

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