title: Incidental spade-shaped FDG uptake in the left ventricular apex suggests apical hypertrophic cardiomyopathy.
abstract: OBJECTIVE
  Apical wall thickening with an "ace-of-spades" configuration is a unique sign of apical hypertrophic cardiomyopathy (AHCM). We investigated spade-shaped FDG uptake around the left ventricular apex (SSUA) incidentally found in routine oncological FDG PET.
  
  
  METHODS
  Cases showing SSUA were selected based on retrospective review. The pattern or intensity of SSUA was compared with the results of electrocardiogram (ECG), echocardiography, and stress myocardial perfusion SPECT. The diagnosis of ACHM was based on the presence of giant negative T wave in ECG, thickness of spade-shaped hypertrophy in the apex in echocardiography, and increased tracer uptake in the apex in rest SPECT.
  
  
  RESULTS
  Among the 34 patients in 36 PET scans showing SSUA, SSUA was weak in 17 and intense in 17. There were isolated SSUA (n = 29) and SSUA with diffuse or other focal left ventricular uptake (n = 5). Three patients with the latter uptake pattern turned out to have coexistence of AHCM and asymmetric septal hypertrophy. Of the 16 SSUA-positive patients who underwent echocardiography, 13 (81%) were diagnosed as AHCM and the remaining 3 were regarded as borderline AHCM (apical wall thickness, 14-15 mm). There were 16 patients with SSUA who also underwent PET scans after the study period among which 11 (69%) had persistent SSUA in the follow-up PET. In the remaining 5, follow-up PET scans showed diffuse left ventricular uptake and SSUA was barely visible. The intensity of SSUA was significantly or marginally associated with giant negative T wave (p < 0.01), apical asynergy (p = 0.08), and impaired coronary flow reserve (p < 0.05). There were no other factors correlated with the pattern or intensity of SSUA.
  
  
  CONCLUSIONS
  SSUA incidentally found in oncological FDG PET appeared to be associated with AHCM, especially in ischemic conditions. The moderate repeatability of SSUA was probably due to obscurity by physiological uptake.
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Katagiri
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan. nakahara@rad.med.keio.ac.jp.
authors.forename: Tadaki
authors.identifier: http://orcid.org/0000-0002-7382-0806
authors.initials: T
authors.lastname: Nakahara
authors.affiliation: Department of Cardiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Mitsushige
authors.initials: M
authors.lastname: Murata
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ogata
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Yohji
authors.initials: Y
authors.lastname: Matsusaka
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Iwabuchi
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Yoshitake
authors.initials: Y
authors.lastname: Yamada
authors.affiliation: Department of Cardiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Fukuda
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Jinzaki
mesh_terms: D000368:Aged; D001692:Biological Transport; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000378:metabolism*; D006801:Humans; D033162:Incidental Findings; D008297:Male; D009369:Neoplasms / Q000150:complications; D000072078:Positron Emission Tomography Computed Tomography; D011379:Prognosis; D012189:Retrospective Studies
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Apical hypertrophy; Echocardiography; Electrocardiogram; FDG PET; Hypertrophic cardiomyopathy; Perfusion SPECT