Fourteen observational studies were included in the review (861 patients, range 24 to 114). There were 12 studies on the performance of PET, seven on the performance of CT, five for PET/CT and one for MRI. Three studies compared a single modality and 11 studies compared two or three modalities.
All the included studies had an adequate reference standard. The reference standard was not part of the index test in three studies and was blinded in 11 studies. The index test was blinded in two studies. Withdrawals were reported in only three studies.
Sensitivity estimates ranged from 74% to 100% for PET (12 studies; seven patient-by-patient based analyses and six lesion-by-lesion based analyses), 69% to 91% for CT (five studies; four patient-by-patient based analyses and one lesion-by-lesion based analysis), 75% to 95% for PET/CT (five studies; two patient-by-patient based analyses and three lesion-by-lesion based analyses) and 73% for MRI (one lesion-by-lesion based analysis). Specificity estimates ranged from 56% to 100% for PET, 50% to 93% for CT, 67% to 98% for PET/CT and 93% for MRI. Pooled estimates were not reported.
Pooled diagnostic odds ratios were 55.2 for PET (95% CI 23.2 to 131.2; 12 studies), 55.3 for PET/CT (95% CI 15.9 to 191.8; five studies) and 9.8 for CT (95% CI 4.2 to 22.8; five studies). The diagnostic odds ratio for the single MRI study was 35.1 (95% CI 13.5 to 90.4).
The area under the SROC curve for recurrence detection was 0.94 (95% CI 0.90 to 0.97) for PET, 0.94 (95% CI 0.87 to 0.98) for PET/CT and 0.83 (95% CI 0.72 to 0.90) for CT. CT had a significantly lower diagnostic performance than PET/CT (p=0.021). No significant differences were found between CT and PET or PET and PET/CT.
The Cochran Q test indicated significant heterogeneity between study results for each imaging modality. In all subgroups CT remained the modality with the lowest diagnostic performance.