Types of pedicle signs indicating symptomatic spinal metastases and their associated clinical and radiological features

Abstract

Background: Cancer diagnoses are increasing rapidly due to the aging population of Japan. Pedicle sign is a valuable radiographic indicator of metastases as the pedicle is the most commonly affected part of the vertebra upon radiographic assessment. However, few detailed studies examining the morphological features of pedicle signs have been performed. To improve the capacity of medical professionals to diagnose symptomatic spinal metastases, we retrospectively examined the morphological characteristics of pedicle signs and their relationship with clinical and radiological features.

Methods: In total, 186 patients with symptomatic spinal metastases who visited our department between January 1, 2011, and December 31, 2017, were enrolled in the study. Pedicle sign was defined as a pedicle that had disappeared or had become obscured on an anteroposterior radiographic image. Radiographic images were evaluated for pedicles and other structures of the vertebrae. Clinical and other radiological features were compared among the types of pedicle signs identified.

Results: Pedicle signs were classified according to whether they had completely disappeared (complete type, 26 patients), partially disappeared (partial type, 40 patients), or were obscured by the osteoblastic background (blastic type, 28 patients). The disappearance of the bone cortex in addition to the pedicle was observed in almost half of the patients with complete and partial types of pedicle signs. Complete types were associated with significantly longer survival rates.

Conclusion: Understanding of the various types of pedicle sign is required to properly diagnose bone metastases.