ABSTRACT
OBJECTIVES: The present study was conducted to examine whether the standardized uptake value (SUV) may be affected by the spatial position of a lesion in the radial direction on positron emission tomography (PET) images, obtained via two methods based on time-of-flight (TOF) reconstruction and point spread function (PSF). METHODS: A cylinder phantom with the sphere (30 mm diameter), located in the center was used in this study. Fluorine-18 fluorodeoxyglucose (18F-FDG) concentrations of 5.3 kBq/ml and 21.2 kBq/ml were used for the background in the cylinder phantom and the central sphere respectively. By the use of TOF and PSF, SUV max and SUV mean were determined while moving the phantom in a horizontal direction (X direction) from the center of field of view (FOV: 0 mm) at 50, 100, 150 and 200 mm positions, respectively. Furthermore, we examined 41 patients (23 male, 18 female, mean age: 68±11.2 years) with lymph node tumors, who had undergone 18F-FDG PET examinations. The distance of each lymph node from FOV center was measured, based on the clinical images. RESULTS: As the distance of a lesion from the FOV center exceeded 100 mm, the value of SUV max , which was obtained with the cylinder phantom, was overestimated, while SUV mean by TOF and/or PSF was underestimated. Based on the clinical examinations, the average volume of interest was 8.5 cm3. Concomitant use of PSF increased SUV max and SUV mean by 27.9% and 2.8%, respectively. However, size of VOI and distance from the FOV center did not affect SUV max or SUV mean in clinical examinations. CONCLUSION: The reliability of SUV quantification by TOF and/or PSF decreased, when the tumor was located at a 100 mm distance (or farther) from the center of FOV. In clinical examinations, if the lymph node was located within 100 mm distance from the center of FOV, SUV remained stable within a constantly increasing range by use of both TOF and PSF. We conclude that, use of both TOF and PSF may be helpful.
ABSTRACT
BACKGROUND AND PURPOSE: Intravenous nicardipine is generally used to treat hypertension in acute stroke patients but is associated with frequent phlebitis. We aimed to identify the incidence and risk factors of phlebitis in such patients. METHODS: The incidence and risk factors of phlebitis were investigated in 358 acute stroke patients from July 2014 to June 2015. RESULTS: In total, 138 patients received intravenous nicardipine. Of 45 (12.6%) phlebitis patients in 358 acute stroke patients, 42 (93.3%) were administered nicardipine, which was significantly associated with phlebitis occurrence (P < .01). Other candidate risk factors of phlebitis of acute stroke patients in univariate analysis were intracerebral hemorrhage (P < .01), nicardipine injection to paralyzed limbs (P = .023), dilution of nicardipine with normal saline (P < .01), higher maximum flow rate of nicardipine (7.2 ± 4.1 mg/h versus 1.6 ± 3.1 mg/h; P < .01), and higher maximum concentration of nicardipine (271.5 ± 145.0 µg/mL versus 37.6 ± 75.0 µg/mL; P < .01). The only statistically significant independent factor following multivariate logistic regression analysis, according to the optimal cutoff values defined from receiver operating characteristic curve analyses, was the maximum concentration of nicardipine greater than 130 µg/mL (OR 57.9; 95% CI 21.5-156; P < .01). A gradual decline of pH below 4.3 was observed when the concentration of nicardipine solution increased to greater than or equal to 130 µg/mL in vitro. CONCLUSIONS: Nicardipine-related phlebitis is frequently observed in acute stroke patients and is significantly associated with administration of a maximum concentration of nicardipine greater than 130 µg/mL.
