99mTc-EC-metronidazole

L,L-ethylenedicysteine (EC) is a new carrier of technetium Tc 99m (99mTc) with a lower affinity to plasma albumin in comparison with diethylenetriamine pentaacetic acid (DTPA). We compared 99mTc-EC scan with 99mTc-DTPA scan in diuretic renography for patients with obstructive uropathy.

Thirty-three patients with upper urinary tract obstruction were randomly selected and underwent diuretic renographies by 99mTc-EC and 99mTc-DTPA. The counts of radioisotope per pixel in the target (the kidney) and background tissues as well as the clearance half-life of these two radiopharmaceuticals were measured and compared.

Mean counts of radioisotope per pixel in the target tissue was not different between 99mTc-EC and 99mTc-DTPA scans, but in the background tissue, it was less for 99mTc-EC (P = .003). Target-background ratio was higher for 99mTc-EC scan (3.80 +/- 2.11 versus 2.48 +/- 1.39; P < .001). Renal clearance half-life of radioisotope was shorter for 99mTc-EC scan than 99mTc-DTPA scan (58.15 +/- 15.17 minutes versus 78.65 +/- 19.99 minutes; P = .033). The results were similar for uremic patients (with a serum creatinine level > 2mg/dL).

Target-background ratio of radiopharmaceutical uptake rates in diuretic renography was a good indicator of the higher resolution of 99mTc-EC than 99mTc-DTPA scan. We also demonstrated the faster clearance of 99mTc-EC than 99mTc-DTPA. This results in less radiation that is especially useful in children. To our opinion, 99mTc-EC can better depict the kidneys in comparison with 99mTc-DTPA.

Background and Purpose— We hypothesized that technetium-99m-ethylene dicysteine-metronidazole ( 99m Tc-EC-MN) localizes to brain tissue that is hypoxic but viable. This study prospectively evaluated the relationship between neurological outcome and uptake of 99m Tc-EC-MN in peri-infarcted regions of the brain. Methods— Eight patients with acute ischemic stroke in the territory of the left middle cerebral artery underwent 99m Tc-EC-MN and 99m Tc-ethyl cysteinate dimer (ECD) brain SPECTs on the same day during the subacute stage (10.3±2.5 days). The infarct volumes from 99m Tc-ECD images (IV ECD ), infarct volumes from diffusion-weighted MRI images (IV DW ), and hypoxic volume (HV) from 99m Tc-EC-MN images were calculated. The net infarct volume (NIV ECD ) was defined as IV ECD minus HV. The National Institutes of Health Stroke Scale scores were measured on admission and days 1, 3, 7, and 30. Results— IV ECD was greater than IV DW . The lesion-to-normal count-density ratios of 99m Tc-EC-MN ranged from 1.80 to 5.96. HV was 60.2±65.2 cm 3 , and the mean percent HV was 24.5±28.1% of IV ECD . NIV ECD was 162.6±133.4 cm 3 and was significantly smaller than IV ECD . NIV ECD was significantly correlated with National Institutes of Health Stroke Scale score at 1 month and was a significant predictor of neurological deficit at 1 month. Conclusions—99m Tc-EC-MN brain SPECT can detect hypoxic tissue after acute ischemic stroke and, in combination with 99m Tc-ECD brain SPECT, is useful in predicting neurological outcome in ischemic stroke patients.