Bull's-eyes and halos: useful MR discriminators of osseous metastases.

Abstract

To evaluate the presence of (a) a focus of high signal intensity in the center of an osseous lesion (bull's-eye) as a negative discriminator for metastasis and (b) a rim of high signal intensity around an osseous lesion (halo) as a positive discriminator, a retrospective study was performed in 47 patients with osseous lesions suspect for metastatic disease who underwent magnetic resonance (MR) imaging of the pelvis. The findings in 17 patients with proved osseous metastasis were compared with those in 30 patients not believed to have metastatic disease; T1- and T2-weighted MR images were evaluated. The bull's-eye sign was found to be a specific indicator of normal hematopoietic marrow (sensitivity, 95%; specificity, 99.5%). The halo sign and diffuse signal hyperintensity were a strong indicator of metastatic disease (sensitivity, 75%; specificity, 99.5%). These results suggest that use of the bull's-eye sign as a discriminator of benign disease and use of the halo sign as a discriminator of metastasis help characterize suspect areas of marrow lesions.

Unusual Manifestations of Vertebral Osteomyelitis: Intraosseous Lesions Mimicking Metastases

“…A peripheral rim of high signal intensity (the halo sign) around an osseous lesion with lower signal intensity on T2-weighted images, thought to represent the mucinous or cellular tissue in a space secondary to the destruction of trabeculae, was most common in osteoblastic metastases from prostate cancer. 17 Even so, the halo sign was also observed in all of our patients with osteomyelitis. The halo sign seen in our study may reflect the hypervascular granulation tissue, a hyperemic response adjacent to thickened trabeculae, at the periphery of the fibrotic or necrotic focus of osteomyelitis.…”

“…13,14,16 The MR imaging criterion for the presence of the "halo sign" was a peripheral rim of high signal intensity on T2-weighted and STIR images around an osseous lesion with lower signal intensity. 17 The MR imaging criterion for the involvement of intervertebral disks was signal-intensity alterations with decreased disk height and an absent intranuclear cleft. …”

Magnetic resonance imaging of bone marrow in oncology, Part 2

“…3) [14]. This halo sign can potentially be useful in evaluating small blastic metastases that might otherwise be mistaken for bone islands (Fig.…”

“…4). In contrast, the bull'seye sign, when present, has been shown to be a useful tool in determining that a region of altered marrow signal is not due to metastasis, with a specificity of 99.5% [14]. The sign consists of one or more foci of high signal (due to fat) present in marrow within a region of low signal intensity on T1-weighted images.…”

Bone island and hand involvement - A short review

“…The study highlights importance of specific attenuation thresholds in order to differentiate osteosclerotic islands from untreated osteoblastic metastatic lesions. The osteosclerotic metastatic lesions also appear hot on bone scan but in MR imaging on fluid sensitive sequences may reveal a halo of bone marrow edema surrounding the lesion [14]. Bone scintigraphy coupled with histopathology may be tried in cases with dubious details [15].…”