Study	No. of participants	Outcomes/comparison	Results
Gandikota 2015	77 (stages IIA ‐ IIB)	Analysis of imaging at different time points: Baseline imaging, imaging during (after two to four cycles of ABVD) and at the end of treatment, follow‐up imaging Need for surveillance imaging	Analysis of imaging at different time points Baseline imaging 77 participants had baseline PET‐CT scans, 1 had only chest X‐ray due to pregnancy at baseline Imaging during and at the end of treatment 77 participants had interim PET‐CT during chemotherapy (N = 34) or after chemotherapy before initiation of radiotherapy (N = 43) Out of 77, 4 remained PET‐positive, scans after completion of radiotherapy showed a complete response in 2/4, inflammation in 1/4, resolution of all adenopathy in 1/4, 0/4 relapsed during follow‐up Follow‐up imaging Median follow‐up: 46 months (range 24 to 126) Total of 466 scans in 78 participants (PET‐CT in N = 42) No relapses occurred in the entire cohort, N = 3 were diagnosed with a second primary malignancy by either imaging or clinical presentation, N = 6 had false‐positive imaging findings (3/6 PET‐CT) requiring further supplementary imaging or biopsy/surgery Need for surveillance imaging Quote: “No relapse of cHL was detected at a median follow‐up of 46 months. […] Routine imaging (either CT or PET‐CT) for the early detection of relapse does not appear necessary or justified in these participants.”
Orlacchio 2012	132 (all stages)	Interim PET2 vs. end PET (three months after the end of chemo‐ and radiotherapy).	Interim PET results Negative interim PET2: 104 Positive interim PET2: 28 End PET results Negative interim PET2 group Negative final PET: 102/104 Positive final PET: 2/104 Positive interim PET2 group Negative final PET: 16/28 Positive final PET: 12/28 Interim PET vs. end PET Negative interim PET2 group Quote: “Final PET confirmed the negative results in 102 cases (98%) and revealed pathological uptake in the remaining two cases (2%).” Positive interim PET2 group Of the 28 interim PET‐positive participants, 19 showed a partial response and nine had disease stability or progression. Twelve of the 28 interim PET‐positive participants had a positive final PET. Hence, the remaining 16 had a negative final PET. NPV and PPV Quote: “Interim PET had a NPV of 98%, with 85.7% sensitivity, 86.4% specificity and 86.4% diagnostic accuracy.” Quote: “[In univariable analysis] the only independent predictor is the result of interim PET. […] PET had a PPV of 42%."