Technetium-99m-pyrophosphate imaging-based computed tomography-guided core-needle biopsy of internal oblique muscle in wild-type transthyretin cardiac amyloidosis
Koji Takahashi, Yoshiyasu Hiratsuka, Takaaki Iwamura, Daisuke Sasaki, Nobuhisa Yamamura, Sohei Kitazawa, Mitsuharu Ueda, Hiroe Morioka, Takafumi Okura, Daijiro Enomoto, Shigeki Uemura, Taizo Kono, Tomoki Sakaue, Shuntaro Ikeda
Abstract
Background Technetium-99m-pyrophosphate (99mTc-PYP) uptake in the internal oblique muscle (IOM), which is often observed in patients with wild-type transthyretin cardiac amyloidosis (ATTR-CA), indicates amyloid transthyretin (ATTR) deposition.Objective This study aimed to assess the safety and efficacy of 99mTc-PYP imaging-based computed tomography (CT)-guided core-needle biopsy of the IOM as a new extracardiac screening biopsy for confirming the presence of ATTR deposits.Methods Patients with suspected ATTR-CA in whom myocardial tracer uptake was detected on chest- and abdomen-centered images of 99mTc-PYP scintigraphy underwent CT-guided core-needle biopsy at the site with the highest tracer uptake in the IOM between September 2021 and November 2022.Results All 18 consecutive patients (mean age, 86.3 years ± 6.5; 61.1% male) enrolled in the study showed 99mTc-PYP uptake into the IOM. Adequate tissue samples were obtained from all patients except one without serious complications. Immunohistochemical analysis confirmed ATTR deposits in 16/18 (88.9%) patients. In the remaining two patients, ATTR deposits were observed via endomyocardial biopsy. All patients were diagnosed with wild-type ATTR-CA based on transthyretin gene sequence testing results.Conclusion In wild-type ATTR-CA, 99mTc-PYP imaging-based CT-guided core-needle biopsy of the IOM could be used as an extracardiac screening biopsy to confirm the presence of ATTR deposits.