Diagnostic performance of 18F-FDG PET/CT using point spread function reconstruction on initial staging of rectal cancer: a comparison study with conventional PET/CT and pelvic MRI

Masatoshi Hotta; Ryogo Minamimoto; Hideaki Yano; Yoshimasa Gohda; Yasutaka Shuno

doi:10.1186/s40644-018-0137-9

Diagnostic performance of ¹⁸F-FDG PET/CT using point spread function reconstruction on initial staging of rectal cancer: a comparison study with conventional PET/CT and pelvic MRI

Cancer Imaging. 2018 Jan 30;18(1):4. doi: 10.1186/s40644-018-0137-9.

Authors

Masatoshi Hotta¹, Ryogo Minamimoto², Hideaki Yano³, Yoshimasa Gohda³, Yasutaka Shuno³

Affiliations

¹ Division of Nuclear Medicine, Department of Radiology, National Center for Global Health and Medicine, 1-21-1, Shinjuku-ku, Toyama, Tokyo, 162-8655, Japan. masatoshihotta@yahoo.co.jp.
² Division of Nuclear Medicine, Department of Radiology, National Center for Global Health and Medicine, 1-21-1, Shinjuku-ku, Toyama, Tokyo, 162-8655, Japan.
³ Department of Surgery, National Center for Global Health and Medicine, 1-21-1, Shinjuku-ku, Toyama, Tokyo, 162-8655, Japan.

Abstract

Background: Accurate staging is crucial for treatment selection and prognosis prediction in patients with rectal cancer. Point spread function (PSF) reconstruction can improve spatial resolution and signal-to-noise ratio of PET imaging. The aim of this study was to evaluate the effectiveness of ¹⁸F-FDG PET/CT with PSF reconstruction for initial staging in rectal cancer compared with conventional PET/CT and pelvic MRI.

Methods: A total of 59 patients with rectal cancer underwent preoperative ¹⁸F-FDG PET/CT and pelvic MRI. The maximum standardized uptake value (SUVmax) and lesion to background (L/B) ratio of possible metastatic lymph nodes, and metabolic tumor volumes (MTVs) of primary tumors were calculated. For N and T (T1-2 vs T3-4) staging, sensitivities, specificities, positive predictive values, negative predictive values, and accuracies were compared between conventional PET/CT [reconstructed with ordered subset expectation maximization (OSEM)], PSF-PET/CT (reconstructed with OSEM+PSF), and pelvic MRI. Histopathologic analysis was the reference standard.

Results: For N staging, PSF-PET/CT provided higher sensitivity (78.6%) than conventional PET/CT (64.3%), and pelvic MRI (57.1%), and all techniques showed high specificity (PSF-PET: 95.4%, conventional PET: 96.7%, pelvic MRI: 93.5%). SUVmax and L/B ratio were significantly higher in PSF-PET/CT than conventional-PET/CT (p < 0.001). The accuracy for T staging in PSF-PET/CT (69.4%) was not significantly different to conventional PET/CT (73.5%) and pelvic MRI (73.5%). MTVs of PSF and conventional PET showed a significant difference among T stages (p < 0.001), with higher values in advanced stages. In M staging, both PSF and conventional PET/CT diagnosed all distant metastases correctly.

Conclusions: PSF-PET/CT produced images with higher lesion-to-background contrast than conventional PET/CT, which allowed improved detection of lymph node metastasis without compromising specificity, and showed comparable diagnostic value to MRI in local staging. PSF-PET/CT is likely to have a great value for initial staging in rectal cancer.

Keywords: 18F-FDG pet/ct; Pelvic MRI; Point spread function (PSF); Rectal cancer; Staging.

Publication types

Comparative Study
Evaluation Study

MeSH terms

Aged
Female
Fluorodeoxyglucose F18
Humans
Image Processing, Computer-Assisted / methods*
Image Processing, Computer-Assisted / standards
Magnetic Resonance Imaging / methods*
Magnetic Resonance Imaging / standards
Male
Middle Aged
Neoplasm Staging
Pelvis / diagnostic imaging
Positron Emission Tomography Computed Tomography / methods*
Positron Emission Tomography Computed Tomography / standards
Radiopharmaceuticals
Rectal Neoplasms / diagnostic imaging*
Rectal Neoplasms / pathology
Sensitivity and Specificity

Substances

Radiopharmaceuticals
Fluorodeoxyglucose F18