ABSTRACT
The clinical applicability of dynamic single photon emission tomograpy (SPET) using a dual-head gamma camera equipped with a slip-ring rotational mechanism, referred to as serial SPET, was examined in the present investigation. Serial SPET enables the production of tomographic images for any arbitrary time frame from an arbitrary range of data to 360 degrees. In a pre-clinical evaluation, a correlation between radioactivity concentration and serial SPET counts was evaluated in a phantom with continuous changes in 99mTc concentration. A differential value was obtained from each pair of SPET images; moreover, moving average approximation processing was investigated with respect to the elimination of noise in the data. In 11 and one patient presenting with cerebrovascular disease and meningioma, respectively, changes in SPET counts were evaluated when 99mTc ethyl cysteinate dimer (99mTc-ECD) was continuously administered at a constant rate in the resting state. Furthermore, in six of 11 subjects with cerebrovascular disease, changes occurring in SPET counts were examined by using acetazolamide loading while continuously administering 99mTc-ECD at a constant rate. Consequently, serial SPET enabled the evaluation of changes in radioactivity concentration over time in both the phantom and preliminary clinical studies. Data analysis by differential processing utilizing moving average approximation processing enabled the detection of minor changes in radioactivity concentration. An increase of 15.1+/-5.4% was observed in SPET counts of the unaffected cerebral hemisphere with acetazolamide loading. The response of the affected hemisphere was less prominent. These findings suggest that serial SPET would be an effective technique for the pharmacokinetic analysis of radiopharmaceuticals.
Subject(s)
Brain/blood supply , Brain/diagnostic imaging , Cerebrovascular Disorders/metabolism , Cysteine/analogs & derivatives , Cysteine/pharmacokinetics , Meningioma/metabolism , Organotechnetium Compounds/pharmacokinetics , Tomography, Emission-Computed, Single-Photon/methods , Acetazolamide , Aged , Cerebrovascular Disorders/diagnostic imaging , Feasibility Studies , Female , Gamma Cameras , Humans , Male , Meningioma/diagnostic imaging , Middle Aged , Phantoms, Imaging , Quality Control , Radiopharmaceuticals/pharmacokinetics , Rotation , Tomography, Emission-Computed, Single-Photon/instrumentationABSTRACT
A new index of cerebral blood flow (brain uptake ratio, BUR) using 99mTc-ECD was developed and evaluated in 66 patients (132 cerebral hemispheres). BUR was calculated from brain count in anterior planar image (60-80 sec after injection of 99mTc-ECD) divided by the summation of the count of aortic arch during first transit of radionuclide. BUR correlated well with brain perfusion index (BPI) obtained with Patlak plot method (r = 0.960, p < 0.001). In conclusion, BUR is useful as a simple and non-invasive index reflecting cerebral blood flow.
Subject(s)
Brain/diagnostic imaging , Brain/metabolism , Cerebrovascular Circulation , Cysteine/analogs & derivatives , Organotechnetium Compounds , Adolescent , Adult , Aged , Aged, 80 and over , Blood-Brain Barrier , Cerebrovascular Disorders/diagnostic imaging , Cerebrovascular Disorders/physiopathology , Humans , Microspheres , Middle Aged , Organotechnetium Compounds/pharmacokinetics , Perfusion , Radionuclide ImagingABSTRACT
We intended to improve the fractional uptake (FU) method which was developed to quantify cerebral blood flow using 123I-IMP without blood sampling. The quantification of cardiac output (CO) using first-pass data was adapted to FU method while the original FU method used CO which was estimated from the body surface area of patients. Time-radioactivity curves of the lungs and brain were separately obtained by a small-field-of-view gamma camera. In 24 cases, mean cerebral blood flow (mCBF) obtained by the modified FU method showed the better correlation (r = 0.833, P< 0.001) to mCBF measured by the Patlak plot with 99mTc-HMPAO than the original FU method (r=0.667, p<0.01). With these modifications, the reliability of FU method could be improved and the modified FU method might be performed in the other institutions.
Subject(s)
Amphetamines , Cerebrovascular Circulation , Iodine Radioisotopes , Adult , Aged , Aged, 80 and over , Cardiac Output , Female , Humans , Iofetamine , Male , Middle Aged , Tomography, Emission-Computed, Single-PhotonABSTRACT
In order to reduce radiation dose to the hands of examiners who prepare and aspirate radiopharmaceuticals, we made a prototype of simplified manually-operated dispense system, which the syringe and the vial shield with lead were set in the small box made of lead and lead glass. The result showed that our dispense system allowed substantial reduction of radiation dose to the hands and rapid preparation of radiopharmaceuticals compared with the conventional lead shield syringe system, and allowed closer operation, smaller dead volume and lower cost compared with the conventional automatic system.
