Annals of Nuclear Medicine

, Volume 23, Issue 4, pp 349–354

Adrenal masses: the value of additional fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in differentiating between benign and malignant lesions

  • Masahiro Okada
  • Taro Shimono
  • Yoshihiro Komeya
  • Rina Ando
  • Yuki Kagawa
  • Takashi Katsube
  • Masatomo Kuwabara
  • Yukinobu Yagyu
  • Seishi Kumano
  • Izumi Imaoka
  • Norio Tsuchiya
  • Ryuichiro Ashikaga
  • Makoto Hosono
  • Takamichi Murakami
Original Article

DOI: 10.1007/s12149-009-0246-4

Cite this article as:
Okada, M., Shimono, T., Komeya, Y. et al. Ann Nucl Med (2009) 23: 349. doi:10.1007/s12149-009-0246-4

Abstract

Objective

To investigate whether integrated fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) can differentiate benign from adrenal malignant lesions on the basis of maximum standardized uptake value (SUVmax), tumor/liver (T/L) SUVmax ratio, and CT attenuation value (Hounsfield Units; HU) of unenhanced CT obtained from FDG-PET/CT data.

Methods

We studied 30 patients with 35 adrenal lesions (16 adrenal benign lesions, size 16 ± 5 mm, in 15 patients; and 19 adrenal malignant lesions, 24 ± 12 mm, in 15 patients) who had confirmed primary malignancies (lung cancer in 23 patients, lymphoma in 2, esophageal cancer in 2, hypopharyngeal cancer in 1, prostate cancer in 1, and 1 patient in whom lesions were detected at cancer screening). All patients underwent PET/CT at 1 h post FDG injection. Diagnosis of adrenal malignant lesions was based on interval growth or reduction after chemotherapy. An adrenal mass that remained unchanged for over 1 year was the standard used to diagnose adrenal benign lesions. Values of FDG uptake and CT attenuation were measured by placing volumetric regions of interest over PET/CT images. Adrenal uptake of SUVmax ≥ 2.5 was considered to indicate a malignant lesion; SUVmax < 2.5 was considered to indicate a benign lesion. In further analysis, 1.8 was employed as the threshold for the T/L SUVmax ratio. Unenhanced CT obtained from PET/CT data was considered positive for adrenal malignant lesions based on a CT attenuation value ≥ 10 HU; lesions with a value < 10 HU were considered adrenal benign lesions. Mann–Whitney’s U test was used for statistical analyses.

Results

SUVmax in adrenal malignant lesions (7.4 ± 3.5) was higher than that in adrenal benign lesions (2.1 ± 0.5, p < 0.05). The CT attenuation value of adrenal malignant lesions (27.6 ± 11.9 HU) was higher than that of adrenal benign lesions (10.1 ± 12.3 HU, p < 0.05). In differentiating between adrenal benign and malignant lesions, a CT threshold of 10 HU corresponded to a sensitivity of 57%, specificity of 94%, accuracy of 74%, positive predictive value of 92% and negative predictive value of 65%. An SUVmax cut-off value of 2.5 corresponded to a sensitivity of 89%, specificity of 94%, accuracy of 91%, positive predictive value of 94% and negative predictive value of 88%. The T/L SUVmax ratio was 1.0 ± 0.2 for adrenal benign lesions and 4.5 ± 3.0 for adrenal malignant lesions. And T/L SUVmax ratio cut-off value of 1.8 corresponded to a sensitivity of 85%, specificity of 100%, accuracy of 91%, positive predictive value of 100% and negative predictive value of 83%.

Conclusions

FDG-PET/CT with additional SUVmax analysis improves the diagnostic accuracy of adrenal lesions in cancer patients.

Keywords

Adrenal gland Adrenal tumor FDG-PET/CT SUVmax CT attenuation value 

Copyright information

© The Japanese Society of Nuclear Medicine 2009

Authors and Affiliations

  • Masahiro Okada
    • 1
  • Taro Shimono
    • 1
  • Yoshihiro Komeya
    • 1
  • Rina Ando
    • 1
  • Yuki Kagawa
    • 1
  • Takashi Katsube
    • 1
  • Masatomo Kuwabara
    • 1
  • Yukinobu Yagyu
    • 1
  • Seishi Kumano
    • 1
  • Izumi Imaoka
    • 1
  • Norio Tsuchiya
    • 1
  • Ryuichiro Ashikaga
    • 1
  • Makoto Hosono
    • 1
  • Takamichi Murakami
    • 1
  1. 1.Department of RadiologyKinki University School of MedicineOsaka-SayamaJapan

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