Diagnostic value of apparent diffusion coefficients to differentiate benign from malignant vertebral bone marrow lesions

https://doi.org/10.1016/j.ejrad.2007.11.037Get rights and content

Abstract

Aim

The aim of this study is to evaluate the value of the apparent diffusion coefficient (ADC) obtained in diffusion-weighted (DW) MR sequences for the differentiation between malignant and benign bone marrow lesions.

Method

Forty-five patients with altered signal intensity vertebral bodies on conventional MR sequences were included. The cause of altered signal intensity was benign osteoporotic collapse in 16, acute neoplastic infiltration in 15, and infectious processes in 14; based on plain-film, CT, bone scintigraphy, conventional MR studies, biopsy or follow-up. All patients underwent isotropic DW MR images (multi-shot EPI, b values of 0 and 500 s/mm2). Signal intensity at DW MR images was evaluated and ADC values were calculated and compared between malignancy, benign edema and infectious spondylitis.

Results

Acute malignant fractures were hyperintense compared to normal vertebral bodies on the diffusion-weighted sequence, except in one patient with sclerotic metastases. Mean ADC value from benign edema (1.9 ± 0.39 × 10−3 mm2/s) was significantly (p < 0.0001) higher than untreated metastasic lesions (0.9 ± 1.3 × 10−3 mm2/s). Mean ADC value of infectious spondilytis (0.96 ± 0.49 × 10−3 mm2/s) was not statistically (p > 0.05) different from untreated metastasic lesions. ADC value was low (0.75 × 10−3 mm2/s) in one case of subacute benign fracture.

Conclusions

ADC values are a useful complementary tool to characterize bone marrow lesions, in order to distinguish acute benign fractures from malignant or infectious bone lesions. However, ADC values are not valuable in order to differentiate malignancy from infection.

Introduction

Although the spine is the most common site of bone metastases [1], benign vertebral fractures due to osteopenia occur in one third of cancer patients, making it essential to determine whether the cause of vertebral collapse is benign or malignant [2].

Conventional magnetic resonance (MR) techniques are the imaging test of choice in the diagnosis of pathologic fractures; however, they are unable to differentiate acute benign collapse from malignant collapse in most cases. Because osseous edema secondary to acute osteopenic fracture produces signal changes similar to those observed in bone metastases on T1- and T2-weighted and STIR images, conventional MR is very sensitive but not always specific [3], [4], motivating the search for new sequences to provide different information to enable benign lesions to be confidently distinguished from malignant ones. The majority of the authors have used balanced steady-state free precession (SSFP) sequences because they provide very good image quality and the acquisition time is short [5], [6], [7], [8], [9]. These studies have generated much controversy because this sequence does not allow an objective evaluation of the lesion. Some investigators have used other diffusion weighted imaging (DWI) techniques that allow for the calculation of apparent diffusion coefficient (ADC) values [10], [11], [12], [13], showing significant separation between pathologic and benign compression fractures ADC values. Nevertheless, the value of the differentiated malignant from benign vertebral body fractures is not yet clear.

The purpose of this study is to assess the usefulness of diffusion-weighted imaging and of the apparent diffusion coefficient (ADC) obtained in a multishot echo-planar sequence in the differentiation between acute benign bone marrow lesions and malignant lesions in order to increase the specificity of MR.

Section snippets

Patients and methods

From October 2005 to June 2006, 45 consecutive patients (23 men and 22 women; mean age, 61 yrs; range 25–94) presenting vertebral collapse and/or altered signal intensity in one or more vertebral body on conventional MR sequences were studied. Ethics committee approval was considered unnecessary as no ionizing radiation, contrast agents, or invasive techniques were employed. All patients gave informed consent to participate in the study. Nineteen patients had a history of a known primary tumor

Results

The ADC values are summarized in Fig. 1.

Benign collapse occurred in 30 patients. The majority were acute fractures (n = 15), two of whom had a previous history of neoplasm (one lung neoplasm and one breast cancer). One patient presented a subacute benign fracture. Fourteen of the 30 benign lesions were due to infectious spondylitis.

All benign vertebral body lesions were diffusely hypointense at T1-weighted images, hyperintense on T2-weighted images and STIR sequences. Qualitative evaluation of

Discussion

Diffusion-weighted sequences provide dynamic and microscopic information to supplement the static and macroscopic information provided by conventional sequences. Diffusion-weighted sequences reflect the random movement of water molecules (which includes both intracellular and extracellular movement, as well as transcellular and intracapillary movement). A fundamental use for this technique has already been established in the study of hyperacute cerebral infarction, but its uses in other areas,

Conclusions

Despite the lack of histological proof in some patients, we conclude from our results that ADC values represent a useful complementary tool in the differentiation between acute benign fractures from malignant and infectious lesions, but they do not help differentiate malignancy from infection. It is of vital importance to know the age of subacute benign lesions, as the ADC values for these lesions overlap with those of malignant and infectious lesions. Further studies with larger series are

References (23)

  • V. Ratanatharathorn et al.

    Epidural spinal cord compression from metastatic tumor: diagnosis and guidelines for management

    Cancer Treat Rev

    (1991)
  • V.L. Fornasier et al.

    Collapsed vertebrae: a review of 659 autopsies

    Clin Orthop Relat Res

    (1978)
  • W.T. Yuh et al.

    Vertebral compression fractures: distinction between benign and malignant causes with MR imaging

    Radiology

    (1989)
  • A. Baur et al.

    Acute osteoporotic and neoplastic vertebral compression fractures: fluid signat MR imaging

    Radiology

    (2002)
  • A. Baur et al.

    Diffusion-weighted imaging of bone marrow: current status

    Eur Radiol

    (2003)
  • A. Baur et al.

    Diffusion-weighted MR imaging of bone marrow: differentiation of benign versus pathologic compression fractures

    Radiology

    (1998)
  • W.M. Byun et al.

    Diffusion-weighted MR imaging of metastatic disease of the spine: assessment of response to therapy

    AJNR Am J Neuroradiol

    (2002)
  • R. Abanoz et al.

    Diffusion-weighted imaging of acute vertebral compression: differential diagnosis of benign versus malignant pathologic fractures

    Tani Girisim Radyol

    (2003)
  • A. Baur et al.

    Diagnostic value of increased diffusion weighting of a steady-state free precession sequence for differentiating acute benign osteoporotic fractures from pathologic vertebral compression fractures

    AJNR

    (2001)
  • J.H. Chan et al.

    Acute vertebral body compression fractures: discrimination between benign and malignant causes using apparent diffusion coefficients

    Br J Radiol

    (2002)
  • X.J. Zhou et al.

    Characterization of benign and metastatic vertebral compression fractures with quantitative diffusion MR imaging

    AJNR

    (2002)
  • Cited by (92)

    View all citing articles on Scopus
    1

    Lorenzana, 36, 17002 Girona, Spain. Tel.: +34 972 410 256; fax: +34 972 221 457.

    2

    Av. de França s/n, 17007 Girona, Spain. Tel.: +34 972486020; fax: +34 972483085.

    3

    University of Girona, Department of Computer Science and Applied Mathematics, 17003 Girona, Spain. Tel.: +34 972418421.

    View full text