title: Comparison of single photon emission computed tomography-computed tomography, computed tomography, single photon emission computed tomography and planar scintigraphy for characterization of isolated skull lesions seen on bone scintigraphy in cancer patients.
abstract: OBJECTIVE
  The purpose of this study is to evaluate the added value of single photon emission computed tomography-computed tomography (SPECT-CT) over planar scintigraphy, SPECT and CT alone for characterization of isolated skull lesions in bone scintigraphy (BS) in cancer patients.
  
  
  METHODS
  A total of 32 cancer patients (age: 39.5 ± 21.9; male: female - 1:1) with 36 isolated skull lesions on planar BS, underwent SPECT-CT of skull. Planar BS, SPECT, CT and SPECT-CT images were evaluated in separate sessions to minimize recall bias. A scoring scale of 1-5 was used, where 1 is definitely metastatic, 2 is probably metastatic, 3 is indeterminate, 4 is probably benign and 5 is definitely benign. With receiver operating characteristic analysis area under the curves (AUC) was calculated for each modality. For calculation of sensitivity, specificity and predictive values a Score ≤3 was taken as metastatic. Clinical/imaging follow-up and/or histopathology were taken as reference standard.
  
  
  RESULTS
  Of 36 skull lesions 11 lesions each were on frontal, parietal and occipital bone while three lesions were in the temporal bone. Of these 36 lesions, 16 were indeterminate (Score-3) on planar and SPECT, five on CT and none on SPECT-CT. The AUC was largest for SPECT-CT followed by CT, SPECT and planar scintigraphy, respectively. Planar scintigraphy was inferior to SPECT-CT (P = 0.006) and CT (P = 0.012) but not SPECT (P = 0.975). SPECT was also inferior to SPECT-CT (P = 0.007) and CT (P = 0.015). Although no significant difference was found between SPECT-CT and CT (P = 0.469), the former was more specific (100% vs. 94%).
  
  
  CONCLUSIONS
  SPECT-CT is better than planar scintigraphy and SPECT alone for correctly characterizing isolated skull lesions on BS in cancer patients. It is more specific than CT, but provides no significant advantage over CT alone for this purpose.
authors.affiliation: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Punit
authors.initials: P
authors.lastname: Sharma
authors.affiliation: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Tarun Kumar
authors.initials: TK
authors.lastname: Jain
authors.affiliation: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Rama Mohan
authors.initials: RM
authors.lastname: Reddy
authors.affiliation: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Nauroze Ashgar
authors.initials: NA
authors.lastname: Faizi
authors.affiliation: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Chandrasekhar
authors.initials: C
authors.lastname: Bal
authors.affiliation: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Arun
authors.initials: A
authors.lastname: Malhotra
authors.affiliation: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
keywords: Bone scintigraphy; computed tomography; metastasis; single photon emission computed tomography; single photon emission computed tomography-computed tomography; skull