Table 4.
Possible false positives and false negatives of bisphosphonate scintigraphy for detecting transthyretin cardiac amyloidosis
| Situation | How to suspect and confirm? | |
|---|---|---|
| False positive | AL amyloidosis | Abnormal SPIE, UPIE or serum free light ratio. Requires histologic confirmation. |
| Hydroxychloroquine cardiac toxicity | Interrogation. Requires histologic confirmation. | |
| AApoAI and AApoAII amyloidosis | Concomitant kidney disease present. Genetic testing. | |
| ApoAIV amyloidosis | Concomitant kidney disease present. Requires histologic confirmation. | |
| Aβ2M amyloidosis | Long-term dialysis (>9 years). Requires histologic confirmation. | |
| Blood pool | Cardiac dysfunction could be present. Use SPECT to detect uptake in myocardium. Delay acquisition. | |
| Rib fractures, valvular/annular calcifications | Use SPECT to detect uptake in myocardium. | |
| Recent myocardial infarction (<4 weeks) | Interrogation. Use SPECT to detect diffuse uptake in myocardium. | |
| False negative | Phe84Leu ATTRv, Ser97Tyr ATTRv | Concomitant neuropathy. Familial disease. Genetic testing. |
| Very mild disease | Requires histologic confirmation. | |
| Delayed acquisition | Shorter acquisition time interval. | |
| Premature acquisition | Prolong acquisition time interval. |
AApoAI, apolipoprotein AI amyloidosis; AApoAII, apolipoprotein AII amyloidosis; AApoAIV, apolipoprotein A-IV amyloidosis; Aβ2M, β2-microglobulin amyloidosis; AL, light-chain amyloidosis; ATTRv, hereditary transthyretin amyloidosis; SPECT, single photon emission computed tomography; SPIE, serum protein electrophoresis with immunofixation; UPIE, urine protein electrophoresis with immunofixation.