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Effects of K2HPO4and iodinated contrast agents in bone-equivalent solutions on the quantitative accuracy of bone single-photon emission computed tomography.

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Title: Effects of K2HPO4and iodinated contrast agents in bone-equivalent solutions on the quantitative accuracy of bone single-photon emission computed tomography.
Authors: Nojima Y; Graduate School of Health Sciences, Niigata University, Niigata, Japan., Suda S; Saiseikai Niigata Kenoh Kikan Hospital, Sanjo, Japan., Yamazaki Y; Graduate School of Health Sciences, Niigata University, Niigata, Japan.
Source: Biomedical physics & engineering express [Biomed Phys Eng Express] 2026 Jun 01; Vol. 12 (3). Date of Electronic Publication: 2026 Jun 01.
Publication Type: Journal Article
Language: English
Journal Info: Publisher: IOP Publishing Ltd Country of Publication: England NLM ID: 101675002 Publication Model: Electronic Cited Medium: Internet ISSN: 2057-1976 (Electronic) Linking ISSN: 20571976 NLM ISO Abbreviation: Biomed Phys Eng Express Subsets: MEDLINE
Imprint Name(s): Original Publication: Bristol : IOP Publishing Ltd., [2015]-
MeSH Terms: Contrast Media*/chemistry , Phosphates*/chemistry , Potassium Compounds*/chemistry , Tomography, Emission-Computed, Single-Photon*/methods , Bone and Bones*/diagnostic imaging , Iodine*/chemistry, Image Processing, Computer-Assisted/methods ; Phantoms, Imaging ; Algorithms ; Humans
Abstract: Quantitative bone single-photon emission computed tomography (SPECT) using99mTc-labeled phosphates has become increasingly feasible due to advances in SPECT/CT technology and reconstruction algorithms. The xSPECT bone algorithm further improves local anatomical fidelity by segmenting CT images into six tissue classes to generate a zone map for context-specific enhancement of spatial resolution. Therefore, when evaluating xSPECT Bone using phantom studies, bone-equivalent solutions must be prepared to ensure that CT values fall within the bone segmentation range. This study aims to clarify how two commonly used substances (dipotassium hydrogen phosphate (K2HPO4) and iodinated contrast agent) affect CT values, zone maps, attenuation coefficients (μ-map), and quantitative accuracy of xSPECT bone. The inner container of the JS 10 SPECT performance phantom was filled with a99mTc solution prepared by dissolving either K2HPO4or iodinated contrast agent in 100 ml of water. Four types of inserts (with no additive or different K2HPO4or iodine concentrations) were placed in the same sectional area. Both K2HPO4and iodine exhibited strong correlations (p< 0.01) between CT values (HU) and mass densities (g ml-1). No significant differences in zone map orμ-map values were observed between K2HPO4and iodine. At equivalent CT values, percentage contrast was significantly higher with iodine than with K2HPO4. Furthermore, K2HPO4demonstrated stable percentage contrast near unity within 158.5-269.7 HU, indicating superior quantitative consistency. The zone maps andμ-maps were similar with K2HPO4and iodine; however, differences in attenuation during SPECT acquisition due to differences in mass density were not considered. This suggests that attenuation correction becomes overcorrected, thereby decreasing quantitative accuracy. These findings indicate that K2HPO4is more suitable than iodine for creating bone equivalent solutions in quantitative bone SPECT phantom studies.
(© 2026 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)
Contributed Indexing: Keywords: CT value; bone SPECT; mass density; phantom study; xSPECT bone
Substance Nomenclature: 0 (Contrast Media)
B7862WZ632 (potassium phosphate)
0 (Phosphates)
0 (Potassium Compounds)
9679TC07X4 (Iodine)
Entry Date(s): Date Created: 20260521 Date Completed: 20260717 Latest Revision: 20260924
Update Code: 20260925
DOI: 10.1088/2057-1976/ae7118
PMID: 42167289
Database: MEDLINE
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  Data: Effects of K&lt;subscript&gt;2&lt;/subscript&gt;HPO&lt;subscript&gt;4&lt;/subscript&gt;and iodinated contrast agents in bone-equivalent solutions on the quantitative accuracy of bone single-photon emission computed tomography.
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  Data: &lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Nojima+Y%22&quot;&gt;Nojima Y&lt;/searchLink&gt;; Graduate School of Health Sciences, Niigata University, Niigata, Japan.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Suda+S%22&quot;&gt;Suda S&lt;/searchLink&gt;; Saiseikai Niigata Kenoh Kikan Hospital, Sanjo, Japan.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Yamazaki+Y%22&quot;&gt;Yamazaki Y&lt;/searchLink&gt;; Graduate School of Health Sciences, Niigata University, Niigata, Japan.
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  Data: &lt;searchLink fieldCode=&quot;JN&quot; term=&quot;%22101675002%22&quot;&gt;Biomedical physics &amp; engineering express&lt;/searchLink&gt; [Biomed Phys Eng Express] 2026 Jun 01; Vol. 12 (3). &lt;i&gt;Date of Electronic Publication: &lt;/i&gt;2026 Jun 01.
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  Data: &lt;i&gt;Original Publication&lt;/i&gt;: Bristol : IOP Publishing Ltd., [2015]-
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  Data: &lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Contrast+Media%22&quot;&gt;Contrast Media*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Contrast+Media+chemistry%22&quot;&gt;chemistry&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Phosphates%22&quot;&gt;Phosphates*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Phosphates+chemistry%22&quot;&gt;chemistry&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Potassium+Compounds%22&quot;&gt;Potassium Compounds*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Potassium+Compounds+chemistry%22&quot;&gt;chemistry&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Tomography%2C+Emission-Computed%2C+Single-Photon%22&quot;&gt;Tomography, Emission-Computed, Single-Photon*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Tomography%2C+Emission-Computed%2C+Single-Photon+methods%22&quot;&gt;methods&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Bone+and+Bones%22&quot;&gt;Bone and Bones*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Bone+and+Bones+diagnostic+imaging%22&quot;&gt;diagnostic imaging&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Iodine%22&quot;&gt;Iodine*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Iodine+chemistry%22&quot;&gt;chemistry&lt;/searchLink&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Image+Processing%2C+Computer-Assisted%22&quot;&gt;Image Processing, Computer-Assisted&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Image+Processing%2C+Computer-Assisted+methods%22&quot;&gt;methods&lt;/searchLink&gt; ; &lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Phantoms%2C+Imaging%22&quot;&gt;Phantoms, Imaging&lt;/searchLink&gt; ; &lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Algorithms%22&quot;&gt;Algorithms&lt;/searchLink&gt; ; &lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Humans%22&quot;&gt;Humans&lt;/searchLink&gt;
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  Data: Quantitative bone single-photon emission computed tomography (SPECT) using&lt;superscript&gt;99m&lt;/superscript&gt;Tc-labeled phosphates has become increasingly feasible due to advances in SPECT/CT technology and reconstruction algorithms. The xSPECT bone algorithm further improves local anatomical fidelity by segmenting CT images into six tissue classes to generate a zone map for context-specific enhancement of spatial resolution. Therefore, when evaluating xSPECT Bone using phantom studies, bone-equivalent solutions must be prepared to ensure that CT values fall within the bone segmentation range. This study aims to clarify how two commonly used substances (dipotassium hydrogen phosphate (K&lt;subscript&gt;2&lt;/subscript&gt;HPO&lt;subscript&gt;4&lt;/subscript&gt;) and iodinated contrast agent) affect CT values, zone maps, attenuation coefficients (μ-map), and quantitative accuracy of xSPECT bone. The inner container of the JS 10 SPECT performance phantom was filled with a&lt;superscript&gt;99m&lt;/superscript&gt;Tc solution prepared by dissolving either K&lt;subscript&gt;2&lt;/subscript&gt;HPO&lt;subscript&gt;4&lt;/subscript&gt;or iodinated contrast agent in 100 ml of water. Four types of inserts (with no additive or different K&lt;subscript&gt;2&lt;/subscript&gt;HPO&lt;subscript&gt;4&lt;/subscript&gt;or iodine concentrations) were placed in the same sectional area. Both K&lt;subscript&gt;2&lt;/subscript&gt;HPO&lt;subscript&gt;4&lt;/subscript&gt;and iodine exhibited strong correlations (p&amp;lt; 0.01) between CT values (HU) and mass densities (g ml&lt;superscript&gt;-1&lt;/superscript&gt;). No significant differences in zone map orμ-map values were observed between K&lt;subscript&gt;2&lt;/subscript&gt;HPO&lt;subscript&gt;4&lt;/subscript&gt;and iodine. At equivalent CT values, percentage contrast was significantly higher with iodine than with K&lt;subscript&gt;2&lt;/subscript&gt;HPO&lt;subscript&gt;4&lt;/subscript&gt;. Furthermore, K&lt;subscript&gt;2&lt;/subscript&gt;HPO&lt;subscript&gt;4&lt;/subscript&gt;demonstrated stable percentage contrast near unity within 158.5-269.7 HU, indicating superior quantitative consistency. The zone maps andμ-maps were similar with K&lt;subscript&gt;2&lt;/subscript&gt;HPO&lt;subscript&gt;4&lt;/subscript&gt;and iodine; however, differences in attenuation during SPECT acquisition due to differences in mass density were not considered. This suggests that attenuation correction becomes overcorrected, thereby decreasing quantitative accuracy. These findings indicate that K&lt;subscript&gt;2&lt;/subscript&gt;HPO&lt;subscript&gt;4&lt;/subscript&gt;is more suitable than iodine for creating bone equivalent solutions in quantitative bone SPECT phantom studies.&lt;br /&gt; (&#169; 2026 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)
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  Data: &lt;i&gt;Keywords: &lt;/i&gt;CT value; bone SPECT; mass density; phantom study; xSPECT bone
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  Data: 0 (Contrast Media)&lt;br /&gt;B7862WZ632 (potassium phosphate)&lt;br /&gt;0 (Phosphates)&lt;br /&gt;0 (Potassium Compounds)&lt;br /&gt;9679TC07X4 (Iodine)
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  Data: 10.1088/2057-1976/ae7118
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  Data: 42167289
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      – SubjectFull: Image Processing, Computer-Assisted methods
        Type: general
      – SubjectFull: Phantoms, Imaging
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      – SubjectFull: Algorithms
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      – SubjectFull: Contrast Media chemistry
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      – SubjectFull: Phosphates chemistry
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      – SubjectFull: Potassium Compounds chemistry
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      – SubjectFull: Tomography, Emission-Computed, Single-Photon methods
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      – SubjectFull: Bone and Bones diagnostic imaging
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      – SubjectFull: Iodine chemistry
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      – TitleFull: Effects of K2HPO4and iodinated contrast agents in bone-equivalent solutions on the quantitative accuracy of bone single-photon emission computed tomography.
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              Text: 2026 Jun 01
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