Diagnostic Accuracy of [11C]PIB Positron Emission Tomography for Detection of Cardiac Amyloidosis.

OBJECTIVES: This dual-site study evaluated the diagnostic accuracy of the method. BACKGROUND: Pittsburgh compound ([11C]PIB) positron emission tomography (PIB-PET) has shown promise as a specific and noninvasive method for the diagnosis of cardiac amyloidosis (CA). METHODS: The study had 2 parts. In the initial study, 51 subjects were included, 36 patients with known CA and increased wall thickness (15 immunoglobulin light chain [AL] and 21 transthyretin [ATTR] amyloidosis) and 15 control patients (7 were nonamyloid hypertrophic and 8 healthy volunteers). Subjects underwent PIB-PET and echocardiography. Sensitivity and specificity of PIB-PET were established for 2 simple semiquantitative approaches, standardized uptake value ratio (SUVR) and retention index (RI). The second part of the study included 11 amyloidosis patients (5 AL and 6 hereditary ATTR) without increased wall thickness to which the optimal cutoff values of SUVR (>1.09) and RI (>0.037 min-1) were applied prospectively. RESULTS: The diagnostic accuracy of visual inspection of [11C]PIB uptake was 100% in discriminating CA patients with increased wall thickness from controls. Semiquantitative [11C]PIB uptake discriminated CA from controls with a 94% (95% confidence interval [CI]: 80% to 99%) sensitivity for both SUVR and RI and specificity of 93% (95% CI: 66% to 100%) for SUVR and 100% (95% CI: 75% to 100%) for RI. [11C]PIB uptake was significantly higher in AL-CA than in ATTR-CA patients (p < 0.001) and discriminated AL-CA from controls with 100% (95% CI: 88% to 100%) accuracy for both the semiquantitative measures. In the prospective group without increased wall thickness, RI was elevated compared to controls (p = 0.001) and 5 of 11 subjects were evaluated as [11C]PIB PET positive. CONCLUSIONS: In a dual-center setting, [11C]PIB PET was highly accurate in detecting cardiac involvement in the main amyloid subtypes, with 100% accuracy in AL amyloidosis. A proportion of amyloidosis patients without known cardiac involvement were [11C]PIB PET positive, indicating that the method may detect early stages of CA.

Low seroprevalence of bartonella species in danish elite orienteers.

In the 1990s, studies were conducted to investigate 16 episodes of sudden unexpected cardiac death (SUCD) among Swedish elite orienteers during the period from 1979 to 1992. A case control study revealed that a significantly higher proportion of Swedish elite orienteers were B. elizabethae seropositive compared to controls. The aim of our study, designed as a case-control study, was to determine whether similarly high rates of B. elizabethae seropositivity were present among Danish elite orienteers. Cases were 43 elite orienteers; controls were 159 blood donors and 63 elite indoor sportsmen. All participants were tested for antibodies against B. henselae, B. quintana and B. elizabethae using immunofluorescent antibody tests. Surprisingly, Bartonella antibodies were only detected in sera from 5 persons: B. henselae from 1 elite orienteer, 1 handball player and 1 blood donor. B. elizabethae antibodies were detected in 1 handball player and 1 basketball player. We found no association between elite orienteers and the prevalence of Bartonella antibody positivity. This is in contrast to the Swedish study, and might be explained by the use of different serological methods in the 2 studies; to determine whether it is a true difference, a new study is needed.