Diagnostic performance of interim and post-treatment PET
Of the 89 patients who completed the interim PET/CT scans (Table 2), 61 (68.5%) patients had a positive PET/CT scan according to the IHPC. The sensitivity, specificity, PPV, NPV, and accuracy of the IHPC were 81.8%, 33.3%, 14.8%, 92.9%, and 39.3%, respectively. Likelihood ratio analysis yielded a +LH value of 1.2 and -LH value of 0.6. The AUC was 0.6 (95% CI: 0.47–0.68). When using the DC-3 cutoff, 52.8% (47/89) of patients had a positive PET/CT. The sensitivity, specificity, PPV, NPV, and accuracy of DC-3 were 81.8%, 51.3%, 19.1%, 95.2%, and 55.1%, respectively. The +LH was 1.7, and the -LH was 0.4. The AUC was 0.7 (95% CI: 0.56–0.76). With the DC-4 cutoff, 22.5% (20/89) of patients had a positive PET/CT. The sensitivity, specificity, PPV, NPV, and accuracy of DC-4 were 27.3%, 78.2%, 15.0%, 88.4%, and 71.9%, respectively. The +LH, -LH, and AUC were 1.3, 0.9, and 0.5 (95% CI: 0.42–0.63), respectively.
Of the 147 patients who completed the post-treatment PET/CT scans (Table 2), 46 (31.3%) had a positive PET/CT scan according to the IHPC. The sensitivity, specificity, PPV, NPV, and accuracy of IHPC were 73.3%, 73.5%, 23.4%, 96.0%, and 73.5%, respectively. In the likelihood ratio analysis, the +LH was 2.8, and -LH was 0.4. The AUC was 0.7 (95% CI: 0.66–0.80). When using the DC-3 cutoff, 24.5% (36/147) of patients had positive PET/CT scans. The sensitivity, specificity, PPV, NPV, and accuracy of DC-3 were 66.7%, 80.3%, 27.0%, 95.5%, and 78.9%, respectively. The +LH, -LH, and AUC were 3.4, 0.4, and 0.7 (95% CI: 0.66–0.80), respectively. According to the DC-4 cutoff, 13.6% (20/147) of patients had positive PET/CT scans. The sensitivity, specificity, PPV, NPV, and accuracy of DC-4 were 46.7%, 90.2%, 33.3%, 93.7%, and 85.7%, respectively. The +LH, -LH, and AUC were 4.7, 0.6, and 0.7 (95% CI: 0.60–0.76), respectively.