Influence of collimator choice and simulated clinical conditions on 123I-MIBG heart/mediastinum ratios: a phantom study.
OBJECTIVE
(123)I presents imaging problems owing to high-energy photon emission. We investigated the influence of collimators on (123)I-MIBG heart/mediastinum ratios (H/M ratios). Secondly, we assessed the influence on H/M ratios of different activity concentrations, simulating clinical conditions. Thirdly, the value of scatter correction was assessed.


METHODS
The AGATE cardiac phantom was filled with (123)I in three sequential conditions: A, heart and mediastinal activity; B, adding lung activity; and C, adding liver activity (protocol I). In protocol II, myocardium and liver were filled with different activities ranging from low to high. For each condition, static anterior planar and single-photon emission computed tomography studies were acquired on a Siemens e.cam (SI) and a General Electric Millennium VG (GE) system, using low-energy high-resolution and medium-energy (ME) collimators for protocol I and only ME collimators for protocol II . For the SI camera, a triple energy window (TEW) scatter correction was applied.


RESULTS
Planar H/M ratios were influenced by scatter and septal penetration from increasing amounts of liver activity. These effects were less pronounced for ME collimators. Although the TEW scatter correction increased ratios overall, TEW correction did not improve the relative differences between the ratios. TEW correction therefore does not add any benefit to obtain an accurate reflection of myocardial activity concentrations.


CONCLUSIONS
For straightforward implementation of semi-quantitative (123)I-MIBG myocardial studies, we recommend the use of ME collimators without scatter correction.
Verberne
Hein J
HJ
Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. h.j.verberne@amc.uva.nl
Feenstra
Christel
C
de Jong
W Matthijs
WM
Somsen
G Aernout
GA
van Eck-Smit
Berthe L F
BL
Busemann Sokole
Ellinor
E
D019797:3-Iodobenzylguanidine / Q000493:pharmacokinetics*; D019544:Equipment Failure Analysis; D006321:Heart / Q000000981:diagnostic imaging*; D007089:Image Enhancement / Q000295:instrumentation*; D008482:Mediastinum / Q000000981:diagnostic imaging* / Q000502:physiology; D009206:Myocardium / Q000378:metabolism*; D009928:Organ Specificity; D019047:Phantoms, Imaging; D011877:Radionuclide Imaging / Q000295:instrumentation* / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine