Verification of reprojected planar images generated from a ring-configured cadmium zinc telluride gamma camera in scintigraphy for diagnosing transthyretin cardiac amyloidosis.

Aims: Non-invasive diagnosis of amyloid transthyretin (ATTR) cardiac amyloidosis using planar scintigraphy and single-photon emission computed tomography-computed tomography (SPECT-CT) with [^99mTc]Tc-3,3-diphosphono-1,2-propanodicarboxylic acid ([^99mTc]Tc-DPD) has high specificity and sensitivity. However, the introduction of ring-configured cadmium zinc telluride (CZT) gamma cameras warrants an update in the acquisition method since these systems are not able to perform planar scintigraphy. We aimed to verify the use of reprojected planar images from SPECT-CT as a replacement for planar scintigraphy in evaluating ATTR-amyloidosis.

Methods and results: The study examined 30 patients referred for clinically indicated [^99mTc]Tc-DPD scintigraphy who were scanned with both a conventional gamma camera and a ring-configured CZT gamma camera. Planar scintigraphy from the conventional gamma camera was compared with reprojected planar images from the ring-configured CZT gamma camera. The images were evaluated in regard to image quality and Perugini visual score in a blinded fashion by three nuclear medicine physicians. Heart-to-contralateral (H/CL) ratios were calculated. There were 27 patients who had an identical Perugini score in planar and reprojected planar images, yielding a strong level of agreement and inter-rater reliability among the three readers. The H/CL ratios showed a strong correlation ratio (r = 0.98, P < 0.0001). A shift towards lower image quality was seen for the reprojected images.

Conclusion: Reprojected planar images generated from a ring-configured CZT gamma camera combined with SPECT-CT can be used to score ATTR amyloidosis and extract H/CL ratios in the same way as planar images and SPECT-CT from a conventional gamma camera.