RT Journal Article
SR Electronic
T1 A New PET Scanner with Semiconductor Detectors Enables Better Identification of Intratumoral Inhomogeneity
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 148
OP 155
DO 10.2967/jnumed.108.054833
VO 50
IS 1
A1 Tohru Shiga
A1 Yuichi Morimoto
A1 Naoki Kubo
A1 Norio Katoh
A1 Chietsugu Katoh
A1 Wataru Takeuchi
A1 Reiko Usui
A1 Kenji Hirata
A1 Shinichi Kojima
A1 Kikuo Umegaki
A1 Hiroki Shirato
A1 Nagara Tamaki
YR 2009
UL http://jnm.snmjournals.org/content/50/1/148.abstract
AB An autoradiography method revealed intratumoral inhomogeneity in various solid tumors. It is becoming increasingly important to estimate intratumoral inhomogeneity. However, with low spatial resolution and high scatter noise, it is difficult to detect intratumoral inhomogeneity in clinical settings. We developed a new PET system with CdTe semiconductor detectors to provide images with high spatial resolution and low scatter noise. Both phantom images and patients' images were analyzed to evaluate intratumoral inhomogeneity. Methods: This study was performed with a cold spot phantom that had 6-mm-diameter cold sphenoid defects, a dual-cylinder phantom with an adjusted concentration of 1:2, and an “H”-shaped hot phantom. These were surrounded with water. Phantom images and 18F-FDG PET images of patients with nasopharyngeal cancer were compared with conventional bismuth germanate PET images. Profile curves for the phantoms were measured as peak-to-valley ratios to define contrast. Intratumoral inhomogeneity and tumor edge sharpness were evaluated on the images of the patients. Results: The contrast obtained with the semiconductor PET scanner (1.53) was 28% higher than that obtained with the conventional scanner (1.20) for the 6-mm-diameter cold sphenoid phantom. The contrast obtained with the semiconductor PET scanner (1.43) was 27% higher than that obtained with the conventional scanner (1.13) for the dual-cylinder phantom. Similarly, the 2-mm cold region between 1-mm hot rods was identified only by the new PET scanner and not by the conventional scanner. The new PET scanner identified intratumoral inhomogeneity in more detail than the conventional scanner in 6 of 10 patients. The tumor edge was sharper on the images obtained with the new PET scanner than on those obtained with the conventional scanner. Conclusion: These phantom and clinical studies suggested that this new PET scanner has the potential for better identification of intratumoral inhomogeneity, probably because of its high spatial resolution and low scatter noise.