Quantification methods for 99mTc-labelled disphosphonates uptake in cardiac amyloidosis

Area of Science:

• Nuclear Medicine
• Cardiology
• Radiology

Background:

• Bone scintigraphy (BS) is crucial for diagnosing transthyretin cardiac amyloidosis (CA).
• Current methods like visual grading and semi-quantitative analysis suffer from subjectivity and operator dependence.
• Absolute quantification techniques are being explored to improve diagnostic accuracy and consistency.

Purpose of the Study:

• To identify and review quantification methods used in assessing CA via bone scintigraphy.
• To evaluate the prevalence and characteristics of different quantification techniques in recent literature.

Main Methods:

• Systematic review of 12 articles from Scopus, PubMed, and Web of Science.
• Focus on studies published within the last 5 years.
• Analysis of quantification methods applied to planar imaging and SPECT/CT for CA assessment.

Main Results:

• Visual grading was used in 100% of studies; semi-quantitative methods in 91.7%; absolute quantification in 33.3%.
• The heart-to-contralateral lung (H/CL) ratio was the most common semi-quantitative method.
• Absolute quantification methods showed heterogeneous cut-off thresholds (1.25-6.1 SUV) for CA discrimination.

Conclusions:

• Visual grading remains the standard, but the H/CL ratio is a frequently reported semi-quantitative alternative with limitations.
• Absolute quantification using SPECT/CT (SUVmax, SUVpeak) shows potential for CA diagnosis, prognosis, and monitoring.
• Consensus reference values for absolute quantification methods are currently lacking.