Asymmetric dimethylarginine is not a good predictor of ischemia using myocardial perfusion scintigraphy.

BACKGROUND/AIM: Asymmetric dimethylarginine (ADMA) plays role in the pathogenesis of coronary artery disease and related mortality and morbidity through a number of mechanisms. We hypothesized that plasma ADMA levels would be increased in the presence of reversible ischemia as measured by GATED single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy (MPS). MATERIALS AND METHODS: Fasting i.v. blood samples were drawn before testing. All patients underwent 99mTc-sestamibi GATED SPECT MPS with a one-day stress-rest protocol; the images were visually analyzed. Post-stress GATED parameters, including ejection fraction, end systolic and end diastolic volumes, and automatic stress defect scores, were recorded. RESULTS: The plasma ADMA levels were higher in the ischemic group than in the non-ischemic group (0.46 ± 0.19 vs. 0.40 ± 0.15; P = 0.016). Plasma ADMA levels (odds ratio [OR] = 13.5; 95% confidence interval [CI] = 1.7-109.01; P = 0.015) and sex (OR = 2.49, 95% CI = 1.18-5.26; P = 0.017) were independent predictors of ischemia. There was no linear correlation between plasma ADMA levels and both the GATED SPECT and stress test parameters. CONCLUSION: Our data support the hypothesis that increased baseline ADMA levels are independently related with the presence of reversible ischemia.

The Scintigraphic Findings of Gastroesophageal Reflux in Children is Related to Body Weight?

BACKGROUND: Gastroesophageal reflux disease (GERD) is the most common cause of children admissions to pediatric gastroenterology unit and affects about 30% of pediatric population. Body weight and height percentiles of children with GERD and their relationship between presence and the severity of reflux on scintigraphic images were studied. METHODS: Patients who underwent reflux scintigraphy between 2005 - 2012 were retrospectively reviewed. Among 200 patients, 49 patients were involved that their ages were ranging from 0 to 18 years old and body weight and height percentiles were recorded. Accurately 37 MBq (1 mCi) 99mTc-MAA in 100 - 150 mL of milk was ingested by the patient. Presence, number, duration and level of reflux were evaluated on the dynamic images. Presences of reflux within last ten minute were also recorded. Region-of-interests were drawn on esophagus and stomach and reflux ratio (RR) was calculated. RESULTS: The ratio of the presence of reflux which occurred within the last ten minutes was significantly higher in children with low body weight percentile. High-level reflux frequency was higher in these children than in normal's. Presence of reflux which occurred within the last ten minutes was related with low body weight percentile. CONCLUSIONS: If reflux is shown within the last ten minutes and there is high level of reflux, the clinician should be warned about possible low body weight percentile in the future and scintigraphic study should be a guide or a reference for the assessment of more effective treatment methods.

Resistin predicts ischemia in myocardial perfusion scintigraphy.

UNLABELLED: Aim: Resistin plays a role in the pathogenesis of coronary artery disease and is related to mortality and morbidity through a number of mechanisms. We hypothesize that plasma resistin levels are increased in the presence of ischemia, as measured by GATED single- photon emission computed tomography myocardial perfusion scintigraphy (SPECT MPS), in comparison with nonischemic subjects. MATERIALS AND METHODS: Fasting intravenous blood samples of patients were drawn before a stress test. An ELISA kit was used for the assays. All patients underwent a technetium 99m-sestamibi GATED SPECT MPS study with a 1-day stress-rest protocol. Images were analyzed visually and patients were assessed as ischemic or nonischemic. Resistin levels were presented as medians (25th-75th percentiles) and were compared using the Mann-Whitney U test. RESULTS: Plasma resistin levels were higher in the ischemic group (n = 47) than in the nonischemic group (n = 67) [9.04 pmol/L (6.27-11.8 µmol/L) vs. 3.56 µmol/L (0.39-7.93 pnol/L), respectively; P < 0.001). We showed that plasma resistin levels (OR = 1.26, 95% CI: 1.13-1.41; P < 0.001) and METs (OR = 0.82, 95% CI: 0.70-0.92; P = 0.021) were independent predictors ofischemia. No linear correlation was found between plasma resistin levels and GATED SPECT or stress test parameters. CONCLUSION: Increased baseline resistin levels are independently related to presence of ischemia but are not related to the extent or severity of ischemia, or other functional parameters such as poststress ejection fraction, end systolic, and end diastolic volumes.

Does PRRT with standard activities of 177Lu-octreotate really achieve relevant somatostatin receptor saturation in target tumor lesions?: insights from intra-therapeutic receptor imaging in patients with metastatic gastroenteropancreatic neuroendocrine tumors.

BACKGROUND: Peptide receptor radionuclide therapy (PRRT) with 177Lu-[DOTA0,Tyr3]octreotate (177Lu-octreotate) is generally performed using a fixed activity of 7.4 GBq (200 mCi) per course bound to 180 to 300 µg of the peptide. While this single activity may lead to suboptimal radiation doses in neuroendocrine tumors (NET) with advanced or bulky disease, dose escalation has been withheld due to concerns on potential tumor somatostatin receptor saturation with reduced efficacy of the added activity. In vivo saturation effects during standard-dose PRRT based on quantification of pre- and intra-therapeutic 68Ga-DOTATOC positron emission tomography (PET) imaging might guide potential dose escalation. METHODS: Five patients with metastatic NET of the pancreas underwent 68Ga-DOTATOC PET/CT before and directly after standard-dose PRRT with 177Lu-octreotate. In each patient, four target tumor lesions, normal liver parenchyma, and the spleen were evaluated and the ratios of SUVmax of the target lesions to liver (SUVT/L) and spleen (SUVT/S) were calculated; paired Student's t test was performed with p < 0.05 for pre-/intra-PRRT comparisons. RESULTS: The mean intra-therapeutic tumor SUVmax showed no significant change (per-lesion paired t test) compared to pretreatment values (-9.1%, p = 0.226). In contrast, the SUVmax of the normal liver parenchyma and spleen were significantly lower directly after infusion of 7.4 GBq 177Lu-octreotate. Consequently, SUVT/L and SUVT/S increased significantly from pretreatment to intra-therapeutic examination: SUVT/L (p < 0.001) from 2.8 ± 1.3 (1.3 to 5.8) to 4.7 ± 3.0 (2.1 to 12.7) and SUVT/S (p < 0.001) from 1.2 ± 0.7 (0.4 to 3.0) to 3.5 ± 1.5 (1.6 to 7.9). CONCLUSIONS: This small retrospective study provides preliminary evidence for the absence of relevant in vivo saturation of somatostatin receptor subtype 2 (sst2) in tumor lesions during PRRT with standard activities of 177Lu-octreotate in contrast to normal tissue (liver, spleen) showing limited receptor capacity. After being confirmed by larger series, this observation will have significant implications for PRRT: (1) Higher activities of 177Lu-octreotate might be considered feasible in patients with high tumor disease burden or clinical need for remission, and (2) striving to reduce the amount of peptide used in standard preparations of 177Lu-octreotate appears futile.

Efficiency of radioactive I-131 therapy in geriatric patients with toxic nodular goiter.

BACKGROUND AND AIMS: The success of I-131 therapy in geriatric patients who were referred to an endocrinology clinic with toxic nodular goiter and who lived in iodine-deficiency regions was studied. MATERIALS AND METHODS: Patients older than 60 years who received I-131 therapy were included via retrospective data analyses. Fifty-nine patients between 60 and 82 years of age were enrolled in the study. The patients received an oral capsular form of I-131 (10-25 mCi) and were followed up for 1 year with clinical and laboratory results. Euthyroid or hypothyroid status at the end of the year after treatment was deemed to be a response to treatment. RESULTS: Of the 21 (36%) male and 38 (64%) female patients, 29 (49%) had a solitary toxic nodule and 30 (51%) had toxic multinodular goiter. Twenty-nine (49%) of the patients received propylthiouracil therapy. At the end of the year, 38 (64%) patients were euthyroid, 11 (19%) were hypothyroid, and 10 (17%) were thyrotoxic. Forty-nine (83%) patients who were euthyroid and hypothyroid were considered responders. CONCLUSION: Geriatric patients with toxic nodular goiter were shown to have a high response rate to I-131 therapy. Thus, we suggest that radioactive iodine treatment should be the first-line treatment in these patients.

Correlation of the vesicular acetylcholine transporter densities in the striata to the clinical abilities of women with Rett syndrome.

Rett syndrome (RTT) is a neurodevelopmental disability characterized by mutations in the X-linked methyl-CpG-binding protein 2 located at the Xq28 region. The severity is modified in part by X chromosomal inactivation resulting in wide clinical variability. We hypothesized that the ability to perform the activities of daily living (ADL) is correlated with the density of vesicular acetylcholine transporters in the striata of women with RTT. The density of the vesicular acetylcholine transporters in the living human brain can be estimated by single-photon emission-computed tomography (SPECT) after the administration of (-)-5-[¹²³I]iodobenzovesamicol ([¹²³I]IBVM). Twenty-four hours following the intravenous injection of ∼333 MBq (9 mCi) [¹²³ I]IBVM, four women with RTT and nine healthy adult volunteer control participants underwent SPECT brain scans for 60 min. The Vesicular Acetylcholine Transporter Binding Site Index (Kuhl et al., 1994), a measurement of the density of vesicular acetylcholine transporters, was estimated in the striatum and the reference structure, the cerebellum. The women with RTT were assessed for certain ADL. Although the striatal Vesicular Acetylcholine Transporter Binding Site Index was not significantly lower in RTT (5.2 ± 0.9) than in healthy adults (5.7 ± 1.6), RTT striatal Vesicular Acetylcholine Transporter Binding Site Indices and ADL scores were linearly associated (ADL = 0.89*(Vesicular Acetylcholine Transporter Binding Site Index) + 4.5; R² = 0.93; P < 0.01), suggesting a correlation between the ability to perform ADL and the density of vesicular acetylcholine transporters in the striata of women with RTT. [¹²³I]IBVM is a promising tool to characterize the pathophysiological mechanisms of RTT and other neurodevelopmental disabilities.