Gangionic plexus (GP) have an associated with initiation and maintenance of AF. Is there a way to accurately locate them with out high intensity frequency (HIF) such as nuclear imaging - MIBG?
If there is a accurate method of locating GP then what methods are currently being employed in the clinical setting which are reproducible and accurate at the same time?
It will be very difficult to pin point the GP using MIBG scan, unless GP is utilizing higher amount of neurotransmitter and has very significantly higher sympathetic neuron and vesicles. You can give a try by analyzing early vs delayed MIBG scans (SPECT or PET) of the heart, by pixel-to-pixel comparison.
Would that be feasible especially if we are looking for higher activity GP only? We are using DSPECT for acquisition and analysis. What modality do you use for atrial anatomy delineation. MRI or CT?
Has been described using DSPECT with CT. Abstract at SNMMI last year from Imperial College in ~ 5 patients undergoing ablation for AF
MRI will be gold standard to delineate atrial anatomy but CT has advantage being very fast and established ECG gating.
I have used 123I-MIBG in humans, imaging [SPECT] both shortly after injection and up to 40 h's after injection in the past. For all of these studies: the dose [as in megabecquerels given] needed is far too high for human use, if you want to *reliable* deliniate the GP. In addition, in theory a combined cardiac- and respiratory-gated SPECT/CT should be used with attenuation correction and scatter correction, otherwise the image resolution will certainly be inadequate. Here the radiation dose and statistics in SPECT will both be limiting factors. At present I would be highly critical about any quantitative study of such nature as *good* scatter correction [using Monte Carlo based methods] is required for multi-gated studies. The resulting resolution simply is not good enough yet. In small animals things are different. For example I have seen results from the group of Beekman that make me believe it is "do-able" but not yet in humans and with standard hospital equipment.
We are only using DSPECT and not standard SPECT. The time for scanning is markedly reduced from 17-19 minutes down to 6 minutes. Rest study is about 80Mbq (mega-Becquerel) and stress study is about 250mega-Becquerel. We are currently testing out results in other preliminary studies.
Your answer surprises me. With a dose of 80 MBq at rest and a normal collimator, ignoring decay / scatter / attenuation / part of patient outside FOV / geometric efficiency / poor algorithmic efficiecy, your 'true' data compromises at most 6E5 events amidst a lot of noise. Given that likely half the photons are scattered, half are attenuated and three quarters will be outside the field of view and that probably the GP will compromise less than 1.5% of the MIBG uptake within the field of view, I am not convinced that it is at all feasable.
I will update you on this as soon as possible. thank you for all your answers.
- Badges
- Science topic
- Similar topics
- Computer Science and Engineering
- Human-Computer Interaction