Planar and SPECT/CT 99m Tc-DPD scintigraphy in cardiac amyloidosis: a single centre experience

Background and Objectives

Cardiac amyloid is an increasingly recognised disorder leading to premature death and severe symptoms. Amyloid transthyretin (ATTR) is known to benefit from specific anti-inflammatory and RNA-modulating treatments. Non-invasive assessment for cardiac ATTR would facilitate targeted treatments. Typically, ATTR is assessed with planar images using Technetium (Tc)-99m-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) scans. This study aims to assess whether single photon emission computed tomography (SPECT) / computed tomography (CT) has additive diagnostic value.

Methods

A retrospective, cross-sectional study assessed 53 patients who had undergone DPD scans between 19/10/2018 and 13/09/2019 at the Westmead Hospital Nuclear Medicine Department. Data collection was from electronic patient record. Data analysis was performed using an Excel worksheet.

Results

Fifty-three scans were performed on, 41(77.36%) males (age range 35-90 years) and 12(22.64%) females (age range 37-88 years). Of 17 patients with cardiac amyloidosis 94.1% had ATTR cardiac amyloidosis and 5.9% apolipoprotein (Apo) 2 cardiac amyloidosis with no AL cardiac amyloidosis. The sensitivity, specificity and diagnostic accuracy of the planar and SPECT/CT DPD scans were 88.2%, 100% and 96.2%, respectively. Five equivocal studies in the Planar and SPECT/CT scan were positive by other imaging methods or biopsy. Better anatomical assessment was possible by SPECT/CT Cardiac MRI or echocardiography had lower sensitivity in detecting cardiac amyloidosis. Good cardiac function with a New York Heart Association (NYHA) assessment of 1 and 2 and good ejection fraction (EF) was noted in 73% of patients with DPD planar positive cardiac amyloidosis.

Conclusions

Our data suggests that SPECT/CT imaging does not add significant value to planar images and should not be adopted in routine clinical practice. Further research is required with outcome data for the subgroup of equivocal DPD studies.