Lymphoma Deauville score 4 v 5. Cut off previously mentioned as uptake >2-3 times liver. Has it been changed to >3? 2. Any advice on PET response assessment in high physiological uptake regions?
a.) The Lugano classification recommends using > 2-3 times liver uptake to differentiate score 4 from score 5. This was incorporated in the guidelines to acknowledge differences in trial methodology between European (> x2 liver uptake = score 5) and UK (> x3 liver uptake = score 5) studies. In the UK, we use > x3 liver uptake to define score

b.) PET response in areas of high physiological uptake is difficult, especially as normal physiological uptake is often > mediastinal blood pool (MBP) and/or liver uptake. Expressing limitations to interpretation in the clinical report is recommended. However, the Lugano classification does state that a complete metabolic response (CMR) can be inferred if residual tumoural uptake is indistinguishable from surrounding normal tissue FDG uptake, even if above MBP and/or liver uptake

Could you elaborate on your point on which patients do not need end of treatment PET please?
If a patient has reached a complete metabolic response (CMR), i.e. 5-Point Scale (5-PS) score ≤ 3, at interim PET-CT (iPET-CT), then end of treatment PET-CT (ePET-CT) is not required. However, some form of end of treatment imaging is required.

Do we need to calculate the collective MTV for all avid lesions or only for the most prominent?
The proposal for metabolic tumour volume (MTV) measurement in lymphoma is to include all lesions that have ≥ SUVmax 4.0 and a volume of ≥ 3cm³.

Can you rely on the liver as a reference organ when there is fatty liver?
I agree. Hepatic uptake varies with hepatic steatosis, e.g. increased FDG uptake if there is acute inflammation, e.g. steatohepatitis. This can make the use of the liver as a reference organ less reliable. I have no doubt however that within all the prospective trials that have been performed using the 5-Point Scale (5-PS), there have been patients with fatty livers, which haven’t undermined the overall efficacy of the 5-PS. However, a case by case approach is sometimes required and interpretation of response in light of the overall clinical picture is most important in such cases where there may be confounders to response assessment.

I presume for the SUV threshold of 4 for MTV we should be using TOF data not noise reducing algorithms such as QCLEAR or UltraHD?
This is what is currently recommended but may change once more data is available regarding novel reconstructions.

Ideal time between chemotherapy cycle and iPET?? Can it be done immediately?
The ideal time to perform a PET-CT in relation to chemotherapy is as long as possible since the chemotherapy infusion and as close to the start of the next chemotherapy infusion/cycle without delaying chemotherapy schedules. Mouse models have demonstrated that the peak chemotherapy induced inflammatory response is between 7-10 days post-chemotherapy infusion, which would likely manifest as areas of false positive FDG uptake.

In DLBCL can we omit the need of BMB based on PET?
Yes, you can. PET-CT has high sensitivity and specificity for the detection of bone marrow disease in DLBCL; there is no significant additional clinical benefit by performing a routine bone marrow biopsy in such cases.

What is the role of PET-CT in staging of indolent lymphoma particularly cutaneous lymphoma?
The additional value of PET-CT in indolent lymphomas is less than in Hodgkin Lymphoma, DLBCL and Follicular Lymphoma. However, in selected cases, e.g. marginal zone lymphoma, where radiotherapy with curative intent is an option, FDG PET-CT can be beneficial. Another indication is if there is a clinical suspicion, e.g. rapid nodal growth, night sweats, weight loss, of high-grade transformation. PET-CT can be performed to help guide biopsy of the most avid site of disease.

Do TB and LAFOV also have adapted reduced exposure from the CT component, or does that remain the same a the standard SAFOV equipment?
We use lower CT absorbed doses and for research purposes sometimes even CT-less acquisition protocols

Do you consider SUV images as multiparametric? technically they’re reconstructed from the last minutes of a dynamic WB scan, when the radiopharmaceutical has already reached it’s uptake time, but they do not require an IF for reconstruction, so would you still name it as multiparametric?
No

I would like to know your experience regarding the minimum quantity of fdg for PET long fov for a Total body (mouth legs).
We have some experiences regarding ultra low-dose injections with FDG on LAFOV PET/CT: Our lowest injection was 0.1MBq/kg acquired for 20-30 min

Do you have an extended FOV PET/MR in your centre? If so, what is your experiences with claustrophobic patients, specially those with suspected diagnosis of dementia, considering the length of the equiment.
Not generally a problem – in fact better than before: the bore is 80 cm wide and the interior white and nicely lit. The prospect of a short-ish scan also helps! (We have the Siemens Quadra)

I would like to know your experience regarding PET MRI. Are 1.5 Tesla MRI or 3 Tesla MRI more efficient, sensitive and specific, all other things being equal?
As far as I am aware, all current hybrid PET-MR scanners have 3T magnets (or even above). A case for 1.5T could well be made!

How many MRI sequences do yo perform in Brain PET/MRI?
Depends on the indication – typically perhaps four or five at most. Also depends on the duration of the intended PET acquisition.