Standard Operating Procedures (SOPs) for the acquisition and reconstruction of brain SPECT with 123-Ioflupane. Flavio Nobili & Silvia Morbelli, Genoa.
These SOPs are –of course- mainly derived from the Guidelines of the European Association of Nuclear Medicine (EANM) published in 2020 (Morbelli S, et al. Eur J Nucl Med Mol Imaging 2020 Jul;47(8):1885-1912).
Patient preparation
Withdraw the commonest drugs known to interfere with DAT:
-Bupropion: withdraw 3 days in advance
-Sertraline: withdraw 5 days in advance
-Modafinil: withdraw 3 days in advance
Block the thyroid block by a single administration of potassium iodide oral solution or Lugol’s solution (equivalent to 100 mg iodide) or potassium iodide tablet, potassium perchlorate (400 mg), or sodium perchlorate (600 mg) should be given at least 1 h before injection of [123I]-FP-CIT (unless known sensitivities to these products are reported).
Injected dose by vein: 140-185 MBq MBq (never below 111 MBq)
Scanning time: scan starts from 3 hrs to 6 hrs post-injection (it is important to be as much as
possible consistent at least within each center: i.e. between 3 and 4 hours).
Voiding : The patient should be encouraged to void prior to the start of acquisition to ensure maximum comfort during the study. The patient should be advised to void after the scan session to minimize radiation exposure.
The patient should be told of the importance of avoiding (voluntary) movements of the head and should be asked for her/his active cooperation. If a patient is uncooperative, sedation can be used. The patient’s head should be only lightly restrained. It is not recommended to fix the head firmly in place.
Equipment.
Both 2-head and 3-head camera are allowed. Brain-dedicated camera are also allowed. Single-head camera are not allowed.
Collimators: LEHR or LEUHR parallel-hole collimators are the first choice as they are largely the most available ones. Fan-beam collimators are allowed but not preferred (attenuation correction coefficient should be adapted in order to reduce inhomogeneity with LEHR/LEUHR acquired images). The LEHR/LEUHR collimators are the most largely used, so please use these collimators if possible.
General purpose collimators are not suitable. The use of medium energy collimators is not allowed (low spatial resolution).
Acquisition parameters.
Energy window: peak energy ± 10% (e.g., : with a peak at 159 KeV: 143-175 KeV).
Matrix: 128×128;
Rotational radius: 15 cm and in any case no higher than 18 cm.
Angular sampling: 3° (360° rotation) allowing 120 projections.
Zoom: acquisition pixel size should be one-third to one-half of the expected resolution; therefore it may be necessary to use a hardware zoom to achieve an appropriate pixel size. Zoom 1.3 – 2 in order to achieve an acquisition voxel dimension between 3 and 4 mm (as close as possible to 2.5). Zoom needs to be applied in acquisition (not when reconstructing images).
Acquisition mode: step and shoot.
Total scan time: depending on the imaging device used, typical scan time for a triple head camera is around 30 min (e.g. 120 projections; 40 projections per head; 45 s/projection) and 30-40 min. for a dual-head camera min (e.g. 120 projections; 60 projections per head; 45 s/projection).
Total counts: > 2 Millions, excluding extracerebral sources, such as salivary glands (in any
case not below 1.5 millions).
Quality control of acquired images: unprocessed projection data should be reviewed in cinematic display prior to reconstruction to assess the presence and degree of motion, target-to-background ratios and other potential artefacts. Inspection of projection data in sinogram form may also be useful. In case of gross artifacts, the acquisition should be repeated immediately.
Reconstruction parameters.
Scatter correction: not requested. If routinely performed, please also provide reconstructed images without scatter correction.
Reconstruction protocol: iterative algorhithms are highly preferred over FBP because of the better spatial resolution. Please provide the filter used (data should be filtered in all three dimension (x,y,z) which can be achieved either by two-dimensional prefiltering of the projection data or by applying a three-dimensional postfilter to the reconstructed data) and number of subset and iterations for iterative algorhithms. Data should be reconstructed at the highest pixel resolution, i.e. one-pixel slice thickness.
Attenuation correction: as in use in your lab. Use Chang method (linear correction coefficient for 123I to be experimentally derived in each lab according to collimator and camera features, typically μ=0.10–0.12 cm−1). If a SPECT-CT system is in use, you may use CT-attenuation correction but this could render your data inhomogeneous with the majority of centers that use Chang method. So please consider to use Chang’s method for the purpose of this study.
Once the reconstructed data are available they should be exported from the work-station as Dicom files and sent to the collecting center in Genoa at the web site address: https://nextmr01.ge.infn.it/edlb_php/index.php