Diagnostic value of heart-to-mediastinum ratio in 99mTc-pyrophospate SPECT/CT for transthyretin cardiac amyloidosis.

In transthyretin cardiac amyloidosis (ATTR-CA), 99mTc-pyrophosphate myocardial scintigraphy (99mTc-PYP) is a diagnostic tool that utilizes visual and quantitative evaluation. However, false positive cases can occur because of tracer accumulation in the blood. We investigated the effectiveness of the heart-to-mediastinum (H/M) ratio of 99mTc-PYP in ATTR-CA diagnosis. We retrospectively included 164 patients who underwent 99mTc-PYP single-photon emission computed tomography/computed tomography between March 2019 and January 2022. The diagnostic accuracy of ATTR-CA was examined by the heart-to-contralateral lung (H/CL) and H/M ratio calculated at 3 hours post-tracer administration. After the exclusion of patients who did not undergo endomyocardial biopsy, 30 patients (15 each with ATTR-CA and without ATTR-CA) were included. The receiver operating characteristic curve used to distinguish ATTR-CA from non-ATTR-CA patients revealed an area under the curve of 0.986 and 0.943, respectively. A H/M ratio of > 1.41 identified ATTR-CA patients with a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100, 93.3, 93.3, and 100%, respectively. Conversely, an H/CL ratio of > 1.3 identified ATTR-CA patients with 100% sensitivity, 40.0% specificity, 62.5% PPV, and 100% NPV. The H/M ratio obtained at 3 hours post-injection has the potential to be a novel indicator for ATTR-CA. © 2022. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.

Citation

Takenori Ikoma, Hayato Ohtani, Kazuto Ohno, Keisuke Iguchi, Kenichiro Suwa, Michifumi Sawada, Yukichi Tanahashi, Atsushi Sakamoto, Masao Saotome, Shintaro Ichikawa, Satoshi Goshima, Yuichiro Maekawa. Diagnostic value of heart-to-mediastinum ratio in 99mTc-pyrophospate SPECT/CT for transthyretin cardiac amyloidosis. Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology. 2023 Aug;30(4):1374-1381

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PMID: 36547805

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