Acquisition Protocols and Correction Methods for Estimation of the Heart-to-Mediastinum Ratio in 123I-Metaiodobenzylguanidine Cardiac Sympathetic Imaging
| Autor: | Keiji Matsunaga, Yutaka Sakamoto, Kei Kikuchi, Yusuke Inoue, Takahiro Iizuka, Yoshihiro Itoh, Yutaka Ogino, Yutaka Abe, Yuji Asano, Hideki Mochizuki |
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| Rok vydání: | 2013 |
| Předmět: |
Sympathetic Nervous System
Materials science Energy window Correction method Septal penetration 123i mibg business.industry Mediastinum Heart Collimator law.invention 3-Iodobenzylguanidine law Image Processing Computer-Assisted Humans Female Radiology Nuclear Medicine and imaging Radionuclide Imaging Nuclear medicine business Aged Retrospective Studies |
| Zdroj: | Journal of Nuclear Medicine. 54:707-713 |
| ISSN: | 2159-662X 0161-5505 |
| Popis: | Septal penetration of high-energy photons affects quantitative results in imaging of 123I-labeled tracers. We investigated acquisition protocols (collimator choice and energy window setting) and correction methods for estimating the heart-to-mediastinum (H/M) ratio in cardiac 123I-metaiodobenzylguanidine (MIBG) imaging. Methods: Four hours after 123I-MIBG injection, 40 patients successively underwent planar anterior chest imaging with the medium-energy (ME) (ME method) and low-energy high-resolution (LEHR) (LEHR method) collimators. A 20% energy window was used for both collimators. Another 40 patients were imaged successively with the ME collimator and a 20% window (ME method), the low-medium-energy (LME) collimator and a 20% window (LME20 method), and the LME collimator and a 15% window (LME15 method). The H/M ratios obtained by the LEHR, LME20, and LME15 methods were corrected using their correlations with the H/M ratio obtained by the ME method (empiric correction). The 123I-dual-window (IDW) correction was also applied to remove the influence of high-energy photons. Results: Without correction, severe underestimation of the H/M ratio was shown for the LEHR method using the ME method as a standard, and this underestimation increased with increasing H/M ratios. Underestimation substantially decreased using the LME20 method and further using the LME15 method. Empiric correction reduced the error in the H/M ratio by the LEHR method, but the error was still evident. After empiric correction, the H/M ratios with the LME collimator were comparable to those with the ME collimator. The IDW correction only partially reduced underestimation by the LEHR method and caused a small overestimation for the LME15 method. Conclusion: The use of an LME collimator appears to be acceptable for cardiac 123I-MIBG imaging as an alternative to an ME collimator, and the application of a 15% energy window is recommended when an LME collimator is used. Empiric correction is also expected to improve exchangeability between H/M ratios calculated with ME and LME collimators. Neither the use of an LEHR collimator nor the use of IDW correction is recommended. |
| Databáze: | OpenAIRE |
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