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We compared fractal analysis, a descriptor of macro- and microvascular ischemia patterns, with relative myocardial blood flow (MBF) for detecting obstructive CAD stratified by remote flow.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Materials and methods<\/jats:title>\n                    <jats:p>This secondary analysis of the prospective multi-center AMPLIFiED trial included patients who underwent invasive coronary angiography (ICA) with fractional flow reserve (FFR) and dynamic stress CTP. Obstructive CAD was defined invasively (stenosis\u2009\u2265\u200990% or FFR\u2009&lt;\u20090.8). We assessed diagnostic accuracy of fractal analysis and relative MBF in patient groups subdivided into high, intermediate, and low remote flow.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      In 148 patients (30% female; 416 vessels), obstructive CAD was present in 71\/148 patients (48%), while signs of microvascular ischemia were found in 26\/148 patients (prevalence in high, intermediate, low remote flow: 9%, 37%, 70%). Fractal analysis outperformed relative MBF in detecting obstructive CAD (patient-based sensitivity and specificity: 94% and 92% versus 80% and 64%,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.005). In vessel-based subgroup analysis, both methods performed comparably in high remote flow (area under the receiver-operating curve [AUC]: 0.94 versus 0.88,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.45), while fractal analysis outperformed relative MBF in intermediate and low remote flow (AUC: 0.93 versus 0.77,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.004; 0.92 versus 0.6,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Fractal analysis eliminates reliance on remote flow for CTP imaging, which improves diagnostic accuracy for obstructive CAD particularly in patients with reduced remote flow or microvascular ischemia.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Trial registration<\/jats:title>\n                    <jats:p>This study reports about data from the prospective, multi-center AMPLIFiED trial (UMIN000016353).<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1007\/s11604-025-01883-6","type":"journal-article","created":{"date-parts":[[2025,10,8]],"date-time":"2025-10-08T09:14:22Z","timestamp":1759914862000},"page":"277-290","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Fractal analysis of dynamic stress myocardial CT perfusion decouples diagnostic accuracy for obstructive coronary artery disease from remote flow"],"prefix":"10.1007","volume":"44","clinical-trial-number":[{"clinical-trial-number":"umin000016353","registry":"10.18810\/umin-japan"}],"author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5475-0873","authenticated-orcid":false,"given":"Florian","family":"Michallek","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Satoshi","family":"Nakamura","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masafumi","family":"Takafuji","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Naoki","family":"Nagasawa","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tairo","family":"Kurita","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kaoru","family":"Dohi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hideki","family":"Ota","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kensuke","family":"Nishimiya","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryo","family":"Ogawa","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takehito","family":"Shizuka","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hitoshi","family":"Nakashima","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Naoki","family":"Hatori","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yining","family":"Wang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tatsuro","family":"Ito","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marc","family":"Dewey","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hajime","family":"Sakuma","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kakuya","family":"Kitagawa","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2025,10,8]]},"reference":[{"issue":"6","key":"1883_CR1","doi-asserted-by":"publisher","first-page":"536","DOI":"10.1016\/j.jcct.2022.07.002","volume":"16","author":"RC Cury","year":"2022","unstructured":"Cury RC, Leipsic J, Abbara S, Achenbach S, Berman D, Bittencourt M, et al. 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Grants: German Research Foundation (Deutsche Forschungsgemeinschaft, project number: 392304398, Ml 2272\/1\u20132). Florian Michallek, Satoshi Nakamura, and Kakuya Kitagawa currently belong to the Department of Advanced Diagnostic Imaging, which receives endowment support by an unrestricted grant from Siemens Healthcare K.K. and FUJIFILM Medical Co., Ltd. Marc Dewey: patent on fractal analysis of perfusion imaging (jointly with Florian Michallek, EPO 2022 EP3350773A1, and USPTO 2021 10,991,109; approved). Grants: EU (EC-GA 603266 in HEALTH.2013.2.4.2\u20132), DFG (DE 1361\/14\u20131, DE 1361\/18\u20131\/2, BIOQIC GRK 2260\/1, Radiomics DE 1361\/19\u20131 [428222922] and 20\u20131 [428223139] in SPP 2177\/1), GUIDE-IT (DE 1361\/24\u20131), Berlin University Alliance (GC_SC_PC 27), G-BA (01NVF23002), Berlin Institute of Health (Digital Health Accelerator). Editor: Cardiac CT (Springer Nature). Other: hands-on cardiac CT courses (\n                      \n                      ). Institutional research agreements: Siemens, General Electric, Philips, Canon. M.D. was European Society of Radiology (ESR) Publications Chair (2022\u20132025); the opinions expressed in this presentation are the author\u2019s own and do not represent the view of ESR. The other authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Conflict of interest"}},{"value":"Institutional Review Board approval was obtained.","order":3,"name":"Ethics","group":{"name":"EthicsHeading","label":"Ethical approval"}},{"value":"Written informed consent was obtained from all subjects (patients) in this study.","order":4,"name":"Ethics","group":{"name":"EthicsHeading","label":"Informed consent"}}]}}