Quantitative 99mTc-DPD-SPECT/CT assessment of cardiac amyloidosis

Abstract

Introduction Transthyretin (ATTR) amyloidosis is responsible for the majority of cardiac amyloidosis (CA) cases and can be reliably diagnosed with bone scintigraphy and the visual Perugini score. We aimed to implement a quantification method of cardiac amyloid deposits in patients with suspected cardiac amyloidosis and to compare performance to visual scoring. Methods and materials 136 patients received 99mTc-DPD-bone scintigraphy including SPECT/CT of the thorax in case of suspicion of cardiac amyloidosis. Imaging phantom studies were performed to determine the scaling factor for standardized uptake value (SUV) quantification from SPECT/CT. Myocardial tracer uptake was quantified in a whole heart volume of interest. Results Forty-five patients were diagnosed with CA. A strong relationship between cardiac SUVmax and Perugini score was found (Spearman r 0.75, p < 0.0001). Additionally, tracer uptake in bone decreased with increasing cardiac SUVmax and Perugini score (p < 0.0001). ROC analysis revealed good performance of the SUVmax for the detection of ATTR-CA with AUC of 0.96 ± 0.02 (p < 0.0001) with sensitivity 98.7% and specificity 87.2%. Conclusion We demonstrate an accessible and accurate quantitative SPECT approach in CA. Quantitative assessment of the cardiac tracer uptake may improve diagnostic accuracy and risk classification. This method may enable monitoring and assessment of therapy response in patients with ATTR amyloidosis.

Positron emission tomography in the diagnosis and follow-up of transthyretin amyloid cardiomyopathy patients: A systematic review

“…However, PET may still be of added value in the care for ATTR-CM patients as it offers the possibility to quantify the amyloid load. Although recent efforts are made in finding methods to quantify tracer uptake on bone scintigraphy [ 35 , 36 ], it remains challenging and is not yet common practice [ 37 ], unlike in PET. Quantification using kinetic modelling and retention index of PET tracer uptake in ATTR-CM patients could potentially allow for more accurate assessment of disease severity and prognosis, and particularly accurate monitoring of treatment response with the new generation medical drugs or for disease progression [ 21 ].…”

Bone tracers for transthyretin amyloid cardiomyopathy: are [99mTc]Tc-DPD and [99mTc]Tc-HMDP truly equivalent?

“…In both hereditary and wild-type ATTR-CM, serial [ 99m Tc]Tc-DPD SPECT/CT imaging may be a useful tool for measuring and tracking response to disease-specific treatments [22]. Nevertheless, some hereditary ATTR-CM, like Phe64Leu mutation, appears to result in a lack of myocardial uptake of bone tracers [23].…”

Time is a gift: time-dependent uptake of DPD in cardiac amyloidosis

“…Given the advent of new therapies for the treatment of cardiac amyloid, there has been a recent focus in quantifying DPD uptake in the myocardium and standardizing protocols to allow serial imaging to monitor treatment effect in patients with cardiac amyloid. 7,8 Several variables must be considered when performing and interpreting DPD radionuclide imaging, such as dose of radiotracer used, time from injection to imaging, planar vs SPECT, and many others. In comparison to planar imaging, SPECT allows the three-dimensional visualization of radioactivity within the body, which can be used to derive a semi-quantitative representation of radiotracer concentration within different compartments of the body, known as standardized uptake value (SUV).…”