Utility and limitations of 3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy in systemic amyloidosis.
AIMS
Technetium-99m-labelled 3,3-diphosphono-1,2-propanodicarboxylic acid ((99m)Tc-DPD) is a sensitive method for imaging cardiac transthyretin (ATTR) amyloid. We report utility and limitations of (99m)Tc-DPD scintigraphy in 321 patients with suspected cardiac amyloidosis.


METHODS AND RESULTS
The cohort included wild-type ATTR (ATTRwt) amyloidosis in 94 (29%), ATTR-Val122Ile amyloidosis in 38 (12%), hereditary ATTR (ATTRmt) amyloidosis in 46 (14%), primary light-chain (AL) amyloidosis in 44 (14%), secondary (AA) amyloidosis in three (1%), other hereditary amyloidosis types in nine (3%), undetermined types in two (0.5%), and 85 (26.5%) patients in whom systemic amyloidosis was ultimately excluded. All 158 patients with ATTR amyloidosis with clinical cardiac involvement had cardiac (99m)Tc-DPD uptake, with median Grade 2 intensity. Thirteen further ATTR amyloidosis patients without clinical evidence of cardiac involvement also demonstrated (99m)Tc-DPD cardiac uptake. Eighteen of 35 (51%) AL patients with cardiac involvement had (99m)Tc-DPD cardiac uptake (median Grade 1 intensity). SPECT imaging indicates that the apparent reciprocal reduction in bone uptake is due to masking of bone uptake by extensive soft-tissue uptake in ATTR amyloidosis, especially ATTRwt, and ATTR-Val122Ile types.


CONCLUSION
(99m)Tc-DPD scintigraphy is a highly sensitive technique for imaging cardiac ATTR amyloidosis and is an important investigation in the diagnostic pathway of patients with cardiac amyloidosis. It is not specific for ATTR in isolation but must be interpreted in a broad clinical context to avoid dangerous diagnostic errors. Diffuse skeletal muscle uptake identifies muscle as a hitherto unrecognized site that merits investigation as a target organ in ATTR amyloidosis.
['Hutt|David F|DF|', 'Quigley|Anne-Marie|AM|', 'Page|Joanne|J|', 'Hall|Margaret L|ML|', 'Burniston|Maria|M|', 'Gopaul|Dorothea|D|', 'Lane|Thirusha|T|', 'Whelan|Carol J|CJ|', 'Lachmann|Helen J|HJ|', 'Gillmore|Julian D|JD|', 'Hawkins|Philip N|PN|', 'Wechalekar|Ashutosh D|AD|']
D000328:Adult D000368:Aged D000369:Aged, 80 and over D000686:Amyloidosis D001706:Biopsy D004164:Diphosphonates D005260:Female D006331:Heart Diseases D006801:Humans D008297:Male D008875:Middle Aged D015609:Organotechnetium Compounds D011877:Radionuclide Imaging D019275:Radiopharmaceuticals D012680:Sensitivity and Specificity
Transthyretin ATTR 99mTc DPD scintigraphy Cardiac amyloid Soft tissue