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In systemic lupus erythematosus (SLE), brain and kidney are the most frequently affected organs. Measurements of cerebral blood flow and metabolism by means of positron emission tomography (PET) and single-photon emission tomography (SPET) can contribute to the diagnostic assessment of the involvement of the central nervous system (CNS) in SLE. Functional imaging has been proven to be more sensitive than morphological imaging (magnetic resonance imaging and computed tomography). In this report, we present the case of a 70-year-old female patient, suffering from SLE without symptoms of CNS involvement. In addition to a SPET study using technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) and a PET scan with fluorine-18 deoxyglucose (18FDG), a SPET study after acetazolamide injection was performed in order to assess the cerebral perfusion reserve. While the PET scan showed no major abnormalities, and the baseline SPET study revealed only minor changes, the acetazolamide-enhanced SPET study revealed a marked reduction of the cortical perfusion reserve, particularly in both frontal lobes. It is concluded that “preclinical” CNS involvement, mainly caused by pathological mechanisms involving the cerebral blood vessels, can be considered to exist in this patient with SLE.

The clinical application of technetium-99m bicisate (ethyl cysteinate dimer, ECD) for ictal and interictal studies of regional cerebral blood flow (rCBF) in a patient suffering from medically intractable simple and complex partial seizures is reported. The interictal study was performed 60 min p.i. and the ictal studies were performed at 60 min p.i. using an annular crystal single-photon emission tomography (SPET) system dedicated for high-resolution brain SPET imaging. Visual evaluation of the studies was carried out, as well as semiquantitative measurement of regional tracer uptake. Magnetic resonance imaging (MRI) scans revealed atrophy of almost the complete left frontal lobe and the ventral parts of the left temporal lobe, including in part the temporomesial structures. The left parietal and occipital structures and the right hemisphere were normal. The interictal study showed a large perfusion defect involving the whole left frontal lobe as well as the left temporal lobe with remaining small areas of normal cortical tracer uptake. The ictal studies detected circumscribed hyperperfusion within the left mesial temporal lobe (ventral part of the hippocampus). Additionally an increase in perfusion could be seen within the entire remaining left temporal lobe. Semiquantitative evaluation of tracer uptake comparing both studies detected markedly increased uptake within the focus compared to the remaining left temporal lobe. On this basis the newly available tracer for studies of rCBF, 99mTc-bicisate, seems to be of value for the detection of epileptogenic foci. Additionally, the value of ictal rCBF studies in the presurgical evaluation of those patients presenting severe morphological alterations on MRI is clearly underlined by this case.

Abstract: Vascularisation of coralline hydroxyapatite used to replace the enucleated bulb is of critical importance for the uncomplicated implantation of a motility peg connecting the implant with the cosmetic prosthesis. Technetium-99m diphosphopropanedicarboxylic acid (DPD) single-photon emission tomography (SPET) was used to evaluate the rate of vascularisation as well as the time required for completion of vascularisation. Twenty-four patients were enrolled in the study, which was designed to evaluate vascularisation 10 days, 2 months and 4 months after implantation of a coralline implant. Nineteen patients completed the study and the visual impression of the completion of the vascularisation was scored from 0 (no vascularisation) to ++++ (complete vascularisation) for each patient. No tracer accumulation was detected in any patient at the 10-day examination. Increasing vascularisation was demonstrated with time, and full vascularisation of the coralline implant was seen in all but one case by 4 months after implantation. We conclude that vascularisation of ocular coralline hydroxyapatite implants occurs early and is completed by 4 months after implantation in most cases, but should be confirmed at this time by99mTc-DPD SPET.