Comparison of Single Photon Emission Computerised Tomography (SPECT) with Planar Wholebody Bone Scan (WBBS) in Diagnosis of Solitary Vertebral Lesion in Non-Skeletal Malignancies in Terms of Diagnostic Accuracy

Abstract

To compare single photon emission computed tomography (SPECT) with planar whole body bone scan (WBBS) in diagnosis of solitary vertebral lesion in non-skeletal malignancies in terms of diagnostic accuracy. Cross-sectional study. Nuclear Medical Centre, Armed Forces Institute of Pathology, Rawalpindi, July 2014 to June 2016. After fulfilling the inclusion and exclusion criteria and taking written informed consent, 74 patients of various extra-skeletal malignancies were enrolled in the study. Patients were injected with 740 MBq of 99mTc-methylene diphosphonate (MDP) intravenously. WBBS images were acquired in anterior and posterior projections 3 hours after injection. SPECT images of the desired vertebral region were acquired subsequently along with low dose CT. All the images were read by two experienced nuclear medicine physicians. Lesions were diagnosed as definitely benign, indeterminate/equivocal and definitely malignant separately on WBBS and SPECT. With SPECT/CT as gold standard, sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) and accuracy were calculated. For planar WBBS, sensitivity was 91.43%, NPV was 86.96%, specificity was 51.28% and PPV remained 62.75%. For SPECT, sensitivity and NPV were 100%, specificity was 92.31% and PPV remained 92.11%. Accuracy remained 70.27% and 95.95% for planar WBBS and SPECT, respectively. SPECT imaging significantly increases the specificity (p <0.05) of ⁹⁹ᵐTc-MDP skeletal scintiscanning and accurately diagnoses the equivocal lesions as compared to planar images.