Validation of CT Attenuation Correction for High-Speed Myocardial Perfusion Imaging Using a Novel Cadmium-Zinc-Telluride Detector Technique

Abstract

The aim of this study was to validate attenuation correction (AC) using low-dose standard CT for myocardial perfusion imaging (MPI) on a novel ultra fast g-camera with cadmium-zinc-telluride (CZT) detector technology. Methods: Sixty-six patients (body mass index 6 SD, 27.2 6 3.5 kg/m 2 ; range, 19.1-36.0 kg/m 2 ) underwent a 1-d 99m Tc-tetrofosmin adenosine stress-rest imaging protocol with 15-min acquisitions on a standard dualhead SPECT camera. All scans were repeated within minutes on the CZT camera, with 3-min acquisitions for stress (low dose) and 2-min acquisitions for rest (high dose) as recently established. We compared maximum myocardial uptake (20-segment model) from CZT versus standard SPECT MPI by intraclass correlation without and with CT AC. In addition, clinical agreement for each coronary territory for all scans from both devices was assessed, and Bland-Altmann (BA) limits of agreement for percentage uptake were calculated. Results: The clinical agreement between CZT and standard SPECT cameras was 96% for noncorrected low-and high-dose images (r 5 0.90 and BA 5 218 to 15, and r 5 0.91 and BA 5 215 to 16, respectively), and agreement after AC was 96% for low-and 99% for high-dose images (r 5 0.87 and BA 5 216 to 14, and r 5 0.88 and BA 5 216 to 14, respectively). Conclusion: Our results support that AC of MPI on the novel CZT camera, compared with AC MPI on a conventional SPECT camera, is feasible because it provides a high correlation of segmental tracer uptake and an excellent clinical agreement.

Nuclear myocardial perfusion imaging with a novel cadmium-zinc-telluride detector SPECT/CT device: first validation versus invasive coronary angiography

“…All patients underwent an unenhanced 64-slice CT examination on the CT part of the hybrid device during a breath-hold and with prospective ECG-triggering at 75% of the R-R interval as previously reported in detail [3]. Briefly, after acquisition with 2.5 mm section thickness, …”

“…In fact, perfusion images acquired with CZT detectors have recently been shown to benefit from x-ray based CT attenuation correction validated for a CZT detector camera [3]. Consequently, and as a result of the trend towards hybrid devices, a first combined CZT camera integrated on to a multislice CT camera has been developed (Discovery NM/CT 570c, GE Healthcare).…”

“…The Cadmium-ZincTelluride (CZT) semiconductors directly convert radiation into electric signals without any of the steps of violet light production, transport and conversion as occurs in NaI crystals. The new CZT technology is extremely compact and this miniaturization has enabled different vendors to design a stationary array of 9 [2] to 19 [3][4][5] pinhole gamma cameras packed closely and focused on the heart. The serial alignment of 19 detectors in the camera used in the present study allows coverage of the entire heart at all times, rendering time-consuming camera rotation around the patient unnecessary.…”

Extracardiac findings on computed tomography attenuation correction: Is it worth paying extra attention?

“…Meanwhile, even 64-slice CT is used during inspirational breath-hold to acquire CTAC. 2 This not only enables the simultaneous use of these scans for calcium scoring, 7 but might also improve diagnostic accuracy of incidental extracardiac findings. However, despite further technical refinements, due to the lower resolution and limited scanned area of the thorax, even though a pathology might be detected on the images, the absence of pathology on CTAC does not exclude disease, simply because a pathology outside the scan range will invariably remain undetected.…”

“…Due to the profound impact of attenuation artifacts on diagnostic accuracy, especially specificity, 1 several methods like computed tomography attenuation correction (CTAC), 2 prone myocardial perfusion image (MPI) acquisition, 3 or external radionuclide sources like 153 Gd 4 have been developed. CTAC has evolved as the most common standard used, since it not only improves diagnostic accuracy and outcome prediction by reducing attenuation artifacts 1,5,6 but also enables the evaluation of coronary calcium scoring, 7 offering substantial added diagnostic and prognostic value.…”