Effect of External Cooling on 177Lu-PSMA Uptake by the Parotid Glands.

Recent years have seen the start of treatment of metastatic castration-resistant prostate cancer with prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (PRLT), especially 177Lu-PSMA-617. However, PRLT has side effects on the salivary glands that limit the safety of the treatment. The current study aimed to show the effect of external cooling with ice packs on 177Lu-PSMA-617 uptake by the parotid glands (PGs). Methods: The study included 19 patients (mean age, 72.9 y) with metastatic castration-resistant prostate cancer who had been referred for the first time for 177Lu-PSMA-617 treatment and underwent pretreatment 68Ga-PSMA-11 PET/CT. Before the initiation of PRLT, the SUVmax and SUVmean of the right and left PGs were measured on 68Ga-PSMA PET/CT. Frozen ice packs were then affixed over the right PG of each patient for approximately 5 h; 1 h after they were affixed, PRLT was administered. At 4 h after PRLT, head-and-neck SPECT/CT was performed, and at both 4 and 24 h after PRLT, whole-body planar scintigraphy was performed. Regions and volumes of interest were applied for the right and left PGs, and the counts and volumes were determined. Results: Before PRLT, 68Ga-PSMA-11 PET/CT showed no significant difference in SUVmax or SUVmean between the right and left PGs (P > 0.05). At 4 and 24 h after PRLT, planar imaging showed no significant difference in counts between the cooled and noncooled PGs (P > 0.05). Furthermore, at 4 h after PRLT, SPECT/CT showed no significant difference in counts or volumes between the cooled and noncooled PGs (P > 0.05). Conclusion: External cooling does not reduce uptake of 177Lu-PSMA-617 by the PGs.

Positron emission tomography findings in children with infantile spasms and autism.

The purpose of this study was to evaluate positron emission tomography (PET) findings in patients diagnosed with infantile spasms and autism. This study includes 90 patients who were diagnosed with infantile spasms at the Department of Pediatric Neurology in the Istanbul University Medical Faculty between 1995 and 2007. Of the 90 patients, 15 patients who were diagnosed with autism using the Autism Behaviour Checklist and Childhood Autism Rating Scale and a control group of nine patients without autism but with infantile spasms underwent PET examination. Mean patient age (± standard error, SE) varied between 3 years and 16 years (7.8 ± 4 years), while the mean follow-up time (±SE) varied between 2 years and 16 years (average: 7.1 ± 4 years). Autism was present in 11 patients with symptomatic spasms and in four patients with cryptogenic spasms (p=0.009). On the PET scans of the 15 patients with autism, 13 (86.7%) had significantly decreased metabolic activity in the temporal lobe (p<0.001), nine (60%) had significantly decreased activity in the frontal lobe (p=0.004), and seven (46.7%) had significantly decreased activity in the parietal lobe (p=0.022). In our opinion, hypometabolism in the frontal and parietal lobes, in addition to that previously reported in the temporal lobe, plays a role in the development of autism in patients with infantile spasms.

The value of different washout parameters in the evaluation of renal transplants by technetium-99m-ethylene- l-l-dicysteine.

Technetium-99m-ethylene-l-l-dicysteine ((99m)Tc-EC) is an agent with a potential for renal imaging. It is reported that EC uses the same tubular transporter system as ortho-hippurate (OIH) and mercaptoacetyltriglycine (MAG3) and that this agent has good imaging properties and higher renal clearance than MAG3. In this study we used (99m)Tc-EC to compare different washout parameters in renal transplanted patients. Sixty nine scans in 55 patients (38 males, 17 females) were performed with (99m)Tc-EC during the follow-up period after kidney transplantation. After bolus injection of 280MBq (99m)Tc-EC, 60x1sec and 29x1min images were taken in anterior position. Perfusions of transplanted kidneys were examined visually and perfusion indices (PI) were calculated according to Hilson's method. The semiquantitative washout parameters such as 20 and 30min to peak activity ratios and 20 and 30min to 3min activity ratios were calculated. The patients were clinically evaluated by nephrologists experienced in renal transplantation cases and followed-up by serum creatinine and blood urea nitrogen determinants which were checked every postoperative day until stabilized to a optimal level for each patient. Two standard deviations above the mean values derived from all cases with normal functioning transplanted kidneys were calculated for each method. Then, these values served as the threshold to differentiate the pathological cases respectively. Of the 69 total studies performed, we found 34 normal kidneys, 14 rejections, 19 acute tubular necrosis (ATN) and 2 cyclosporin A toxicity cases. The number of abnormal cases detected with 30/3min, 30/max, 20/3min and 20/max indices were 27, 26, 24, and 18, respectively. In conclusion, we strongly recommend in studying renal transplants to consider the activity at the 3(rd) min post injection as a reference point instead of the time to maximum activity for washout index calculation. If, for any reason the time to maximum counts using (99m)Tc-(peak activity) is prefered, then the period of study should not be performed for less than 30min to achieve reliable results.