Processing

            Inmediately after the end of acquisition, check planar images in cinematic display for movement before starting processing. Correct if possible in the presence of slight movement which will not affect the reconstruction process. Repeat the acqusition in the presence of marked  movement, because correction software results could be misleading in these cases. Also it is important to detect gastrointestinal activity superimposition over the left ventricle. Depending how close to the heart the activity is the type of effect may vary. If adjacent perfusion may appear hotter. If rather distant perfusion may appear decreased. Obtain a delay view after giving a sandwich or milk.

            Reconstruct with iterative rather than backprojection algorythm . It is preferable a fully automatic processing when reorientating and generating the different slices in short, vertical and horizontal axes. Precision is the best for function and perfusion parameters.

            Note LV size and any lung uptake. Attenuation due to breast tissue and diaphragm can also be detected in the planar cinematic display (1).

            Read perfusion slices on the computer screen and in printouts, using color scales or invert black and white. Review polar map images and quantification data. Ideally obtain all quantitative parameters with automatic processing and no operator intervention (2).

            Describe fixed and reversible defects. Assess amount of normal and viable tissue. It is useful for the cardiologist to inform in percentages the ischemic, necrotic and normal/viable tissue, using polar maps or eyeballing estimation (3).

            Analyze RWM and Calculate LVEF and LV volumes (Normal Values).

            Be aware of LBBB and hypertrophy. The first may decrease septum perfusion and the second induce irregular perfusion.

            In patients with 3 vessel disease balanced ischemia may be difficult to detect. In these cases the appearance of abnormal lung uptake after stress, transient dilation in the left ventricle, a drop in ejection fraction and reversible RWMA are all helpful to suspect the diagnosis.

References:


1  Mut F. Diagnostico de la Enfermedad Coronaria and Gonzalez P et al. Viabilidad Miocardica, in Medicina Nuclear Aplicaciones Clínicas. Ignasi Carrio y Patricio González . Editorial Masson, Barcelona España, 2003, p 39-56 and 105-119, respectively.

2  Hesse B et al. EANM/ESC procedural guidelines for myocardial perfusion imaging in nuclear cardiology. Eur J Nucl Med Mol Imaging. 2005 Jul;32(7):855-97.

3  Gonzalez P, Massardo T, Coll C, Humeres P, Sierralta P, Jofre MJ Yovanovich J, Aramburú I, Brugere S, Chamorro H. “The predictive of 201 Tl rest-redistribution and 18F- fluordeoxiglucose SPECT for wall motion recovery after recent reperfused myocardial infarction”. Annals of Nuclear Medicine, vol 18, N°2, 2004, pags 97-103.

4   Burrell Steven and MacDonald Anita. Artifacts and Pitfalls in Myocardial Perfusion Imaging. J Nucl Med Technol 2006; 34:193–211.
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