Performance evaluation of a novel multi-pinhole collimator for dopamine transporter SPECT.

There is a tradeoff between spatial resolution and count sensitivity in SPECT with conventional collimators. Multi-pinhole (MPH) collimator technology has potential for concurrent improvement of resolution and sensitivity in clinical SPECT of 'small' organs. This study evaluated a novel MPH collimator specifically designed for dopamine transporter (DAT) SPECT with a triple-head SPECT camera. Count sensitivity was measured with a 99mTc point source placed on the lattice points of a 1 cm grid covering the whole field-of-view (FOV). Spatial resolution was assessed with a Derenzo type hot rod phantom. An anthropomorphic striatum phantom was scanned with total activity representative of a typical patient scan and different striatum-to-background activity concentration ratios. Recovery of striatum-to-background contrast was assessed by the contrast-recovery-coefficient. Measurements were repeated with double-head SPECT with fan-beam or low-energy-high-resolution-high-sensitivity (LEHRHS) collimators. A patient referred to DAT SPECT because of suspicion of Parkinson's disease was scanned with both LEHRHS and MPH collimators after a single tracer injection. The axial MPH sensitivity profile was approximately symmetrical around its peak, although it was shifted 7 cm towards the patient to simplify positioning. Peak sensitivity of the triple-head MPH system in the center of the FOV was 620 cps MBq-1 compared to 225 cps MBq-1 for the double-head fan-beam system. Sensitivity of the MPH system decreased towards the edges of the FOV. The full width of the sensitivity profile at 200 cps MBq-1 was 21 cm transaxially and 11 cm axially. In MPH SPECT of the Derenzo phantom all rods with ≥ 5 mm diameter were clearly visible. MPH SPECT improved striatal contrast recovery by ≥ 20% compared to fan-beam SPECT. The patient scan demonstrated good image quality of MPH SPECT with almost PET-like delineation of putamen and caudate nucleus. SPECT with dedicated MPH collimators provides considerable improvement of the resolution-sensitivity tradeoff in DAT SPECT compared to SPECT with fan-beam or LEHRHS collimators.

[The effect of chronic alcohol consumption on blood pressure]. / A tartós alkoholfogyasztás hatása a vérnyomásra.

In 1984, a hypertension screening programme was carried out on 13,772 adult subjects in conjunction with a radiological tuberculosis project in the Hungarian town of Csongrád. Among other factors, the effects of a long-lasting and heavy alcohol intake on blood pressure levels were investigated. 21.4% of the men and 2.3% of women admitted to being regular alcohol consumers. Direct and significant relationships were found between the quantity of alcohol consumed and both the systolic (p less than 0.001) and diastolic (p less than 0.05) blood pressures. The prevalence of hypertension (WHO criteria) was higher in heavy drinkers (29.9%) than in abstinent subjects (20.5%, p less than 0.001). When participants were subgrouped according to age groups only the men provided sufficient data. The systolic blood pressure of heavy drinkers was elevated as compared with that of non-drinkers.

A computer algorithm to determine the recognition site of restriction enzymes.

A new algorithm is proposed to determine the type-II restriction endonucleases' recognition site knowing the digested DNA sequence and fragment lengths in an actual case. The algorithm is implemented for the Commodore 64 microcomputer.