Impact of bone SPECT-CT imaging on evaluation of lower extremities' abnormalities

Isis Gayed, David Wan, Charles Beasley, Usha Joseph, John Awad, Susan John

The University of Texas Health Sciences Center at Houston, Houston, TX, USA

Aim: This study aims to investigate the value of single photon emission computed tomography-computed tomography (SPECT-CT) imaging as part of bone scans for evaluation of a variety of pathologies of the lower extremities.
Methods: The study included patients who had undergone SPECT-CT imaging as part of a bone scan between February, 2008 and May, 2009. Patients who had multiple bony metastases were excluded. Two expert readers, informed only of the site of pain, independently interpreted planar images, planar plus SPECT images, and Planar plus SPECT-CT images. The interpretations were graded as: Not certain of etiology (NS), Somewhat certain (SC), and Certain (C). Changes or additions to diagnosis and/or location of pathology were graded as (D).
Results: A total of 35 consecutive patients were included, 19 females and 16 males, with an average age of 44 years. There was agreement between the two readers on the site of pathology in 32 out of 35 patients. The degree of certainty for both readers increased significantly with the addition of SPECT-CT. The certainty of diagnosis increased from 26%, using planar images alone, to 44%, with the addition of SPECT, to 74%, with the addition of SPECT-CT, for Reader 1, and from 40%, to 54%, to 69%, respectively, for Reader 2. SPECT alone added six (17%) new sites of pathology to those identified from planar images, changed the diagnosis for one patient, and added a diagnosis for one other (6%). SPECT-CT changed the diagnosis for three patients, and added another diagnosis for one more patient (11%).
Conclusion: SPECT-CT increased the certainty of location and diagnosis of bony pathology in the lower extremity by at least 30% across a wide variety of abnormalities.

Keywords: lower extremities, SPECT-CT, bone scan