PERCIST 1.0

 

• PET Response Criteria In Solid Tumours 

  When to perform?

  • After the first cycle just before the next one

               -Detect primary resistance to chemotherapy

  • 10 days after the last cycle / End-of-Treatment : 

               -Evaluates restaging

               -If resistance developed mid way

  Required parameter for follow up PET-CT study :

  • Fasting for 4-6 hrs

  • Fasting BG < 200mg/dl

  • 50-70 min post injection

  • FU Scan within 15 min of the baseline

  • Same scanner

  • </= 20% activity

  • To be assessable, difference b/w baseline and follow up SUL in liver must be less than or equal to 20%

    SUL peak:

    The SUL peak (this is a sphere with a diameter of approximately 1.2 cm—to produce a 1-cm3-volume spheric ROI) centered around the hottest point in the tumour foci should be determined, and the image planes and coordinates should be noted (SUL peak).

    

        Background Liver Activity:

  • 3cm ROI mid way between dome & inferior margin excluding central ducts & vessels

  • If diseased –mediastinal background taken, cylindrical ROI in descending aorta, 1cm diameter & 2m long axis.

     

    
    
    

    Measurable tumor Activity

    • 1.5 (mean liver SUL + 2 SDs of mean SUL)

    • If the liver is diseased, 2.0 x (blood-pool 18F-FDG activity + 2SDs in the mediastinum)

    • Tumor sizes more than 2 cm accurate for measurement.

    • Percentage change is calculated

    • PERCIST proposed measurability –only to baseline study. 

      
      
      
      

      Complete Metabolic Response 

      • Complete resolution of 18F-FDG uptake within measurable target lesion so that it is less than mean liver activity and indistinguishable from surrounding background levels. 

      • Disappearance of all other lesions to background levels. 

      • No new 18F-FDG–avid lesions in pattern typical of cancer. 

      • Percentage decline in SUL should be recorded from measurable region, as well as (ideally) time in weeks after treatment was begun (i.e., CMR -90, 4).

        
        
        
        

        
        

      Partial Metabolic Response

      • Reduction of minimum of 30% in target measurable tumor 18F-FDG SUL peak.

      •  Absolute drop in SUL must be at least 0.8 SUL units, as well.

      •  Measurement is commonly in same lesion as baseline but can be      another lesion if that lesion was previously present and is the most active lesion after treatment.

      • No new lesions.

        
        
        
        

        
        

        Stable Metabolic disease:

        • Increase or decrease of SUL peak less than 30%. 

        • Not CMR, PMR, or PMD.

        
        

        Progressive Metabolic Disease:

        • >/= 30% increase in 18F-FDG SUL peak

        • 0.8 SUL unit increase in tumor SUV peak from baseline scan in pattern typical of tumor and not of infection/treatment effect. 

        • New 18F-FDG–avid lesions that are typical of cancer and not related to treatment effect or infection.

        • Unequivocal progression of non target lesions (no definite percentage was defined) 

        • For progressive disease, percentage change, number of weeks & number of new lesions to be mentioned.