Does vitamin E protect salivary glands from I-131 radiation damage in patients with thyroid cancer?

OBJECTIVES: Salivary gland impairment after high-dose radioiodine (¹³¹I) treatment is well recognized. The aim of this study was to determine the protective effect of vitamin E on radiation-induced salivary gland dysfunction in patients undergoing ¹³¹I treatment for differentiated thyroid cancer. METHODS: Thirty-six patients with differentiated thyroid carcinoma were enrolled in this study. They were randomly divided into two groups before postsurgical ablation therapy with 3700-5550 MBq ¹³¹I: the control group, comprising 17 patients, and the vitamin E group, comprising 19 patients. All 19 patients in the experimental group received vitamin E at a dose of 800 IU/day for a duration of 1 week before to 4 weeks after I therapy and the 17 patients in the control group received a placebo for the same duration. Salivary gland function was assessed using salivary gland scintigraphy with intravenous injection of 370 MBq Tc-pertechnetate in two phases, one immediately before and the other 6 months after ¹³¹I ablative therapy. First-minute uptake ratio, maximum uptake ratio, maximum secretion percentage, and excretion fraction (EF) of each salivary gland were measured and compared between the study phases for the two groups. RESULTS: There was no significant difference between preablative and postablative salivary scintigraphic indices in the experimental vitamin E group, whereas maximum secretion percentage and EF of the right submandibular gland and EF of the left parotid gland were significantly decreased in the control group. There was also a higher significant decrease in the EF of the left parotid gland in the control group compared with the vitamin E group. CONCLUSION: Vitamin E consumption may be associated with a significant protective effect against radiation-induced dysfunction in salivary glands following single-dose ¹³¹I therapy in patients with differentiated thyroid cancer.

Withholding or continuing beta-blocker treatment before dipyridamole myocardial perfusion imaging for the diagnosis of coronary artery disease? A randomized clinical trial.

BACKGROUND: Although it has been shown that acute beta-blocker administration may reduce the presence or severity of myocardial perfusion defects with dipyridamole stress, little information is available about the potential effect of chronic beta-blocker treatment on the sensitivity of dipyridamole myocardial perfusion imaging (DMPI). METHODS: As a randomized clinical trial, one hundred twenty patients (103 male and 17 female) with angiographically confirmed CAD who were on long-term beta blocker therapy (≥3 months) enrolled in a randomized clinical trial study. The patients were allocated into two groups: Group A (n=60) in whom the beta-blocker agent was discontinued for 72h before DMPI and Group B (n=60) without discontinuation of beta-blockers prior to DMPI. RESULTS: No significant difference was noted between the groups concerning age, sex, type of the injected radiotracer and number of involved coronary vessels. The mean rank of total perfusion scores for whole myocardium (irrespective of reversibility or irreversibility) in group B was not significantly different from that of group A, (65.75 vs. 55.25, P=0.096). Regarding the only irreversible perfusion defects, the mean rank of perfusion score in group B was higher than that of group A for whole myocardium (72 vs. 49, P=0.0001); however, no difference was noted between two groups for only reversible perfusion defects (61.0 vs. 60.0, P=0.898). The overall sensitivity of DMPI for the diagnosis of CAD in group A (91.7%) was not statistically different from group B (90%). CONCLUSION: Beta-blocker withholding before DMPI did not generally affect the sensitivity of the test for the diagnostic purposes in our study. Thus, beta-blocker withdrawal for just the purpose of diagnostic imaging is not mandatory particularly when medication discontinuation may cause the patients to face increased risk of heart events.

Nasolacrimal duct obstruction as a complication of iodine-131 therapy in patients with thyroid cancer.

PURPOSE: There are few studies evaluating the effect of radioioine therapy on the lacrimal drainage system. This study reports on symptomatic and asymptomatic nasolacrimal duct obstruction (NLDO) as complications of high-dose radioiodine therapy in these patients. METHODS: Eighty-one cases were randomly selected from a population of radioiodine-treated differentiated thyroid carcinoma patients and were enrolled in a historical cohort study. The patients were categorized into four subgroups on the basis of the received cumulative dose of iodine-131 (I-131). In addition, 17 age-matched and sex-matched individuals were selected as the control group. Using dacryoscintigraphy and a clinical datasheet, the patients and controls were evaluated for partial or complete and symptomatic or asymptomatic NLDO. The data on different subgroups of patients were compared with the data of the control group. RESULTS: Twenty-nine out of 162 exposed eyes (18%) and three out of 34 control eyes (9%) had evidence of NLDO on scintigraphic images. Among patients treated with less than 11.1 GBq of I-131 (subgroup A), six out of 78 eyes (7.7%) had partial or complete NLDO. This was evident in 23 out of 84 eyes (27.4%) among patients treated with 11.1 GBq or more (subgroup B). The frequency of complete NLDO increases significantly when the cumulative dose of radioiodine exceeds 11.1 GBq (2.9% in the control group, 3.8% in subgroup A, and 23.8% in subgroup B; P=0.006). CONCLUSION: NLDO may be considered as a side effect of I-131 therapy, especially with a cumulative dose of 11.1 GBq or more.

Low versus high radioiodine dose in postoperative ablation of residual thyroid tissue in patients with differentiated thyroid carcinoma: a large randomized clinical trial.

OBJECTIVES: Radioiodine ablation of thyroid tissue remains the cornerstone of treatment for patients with differentiated thyroid carcinoma after thyroidectomy. Selecting an optimal dose of radioiodine for successful ablation is a continuous challenge in these patients. METHODS: We compared the treatment response of 341 patients with thyroidectomy randomly allocated to the high-dose group, 3700 MBq (170 patients), versus the low-dose group, 1110 MBq (171 patients), for radioiodine ablation therapy in a double-blind randomized clinical trial. The response to treatment was defined as successful or unsuccessful according to post-therapy ultrasonography of the neck, serum thyroglobulin (Tg), anti-Tg, and functioning residual tissue after 6-month and 12-month intervals. The major criteria of successful ablation were Tg<2 ng/ml, anti-Tg<100 IU/ml, and absent remnant in the off-levothyroxine state. Additional radioiodine doses were administered in cases showing no significant response to the first therapy. Finally, the initial outcome, the total hospitalization time, and the cumulative I-131 doses during the 12-month course of the study were compared between the subgroups. RESULTS: The rate of initial successful ablation was 51.6% in all patients, 39.2% in the low-dose group, and 64.1% in the high-dose group. The corresponding success rates at the end of the 12-month follow-up without additional treatment were 55.1, 41.5, and 68.8%, respectively. The relative risk (RR) of unsuccessful ablation for the low-dose versus the high-dose group was 1.695 [95% confidence interval (CI), 1.34-2.14]. In the low-dose group, more patients needed a second dose of I-131, resulting in a higher cumulative activity (median, 4810 vs. 3700 MBq, P<0.0001) and more inpatient time (median 4 vs. 3 days) in comparison with the high-dose group. The covariate factors predicting the treatment response, in order of significance, were radioiodine dose, baseline Tg, baseline thyroid stimulating hormone (TSH) level, efficiency of TSH suppressive therapy, and sex. CONCLUSION: The higher dose of I-131 (3700 MBq) resulted in successful ablation more often than the low dose (1110 MBq).

Quantification and reduction of the collimator-detector response effect in SPECT by applying a system model during iterative image reconstruction: a simulation study.

BACKGROUND: Detector blurring and non-ideal collimation decrease the spatial resolution of the single-photon emission computed tomography (SPECT) images. Iterative reconstruction algorithms such as ordered subsets expectation maximization (OSEM) can incorporate degrading factors during reconstruction. We investigated the quantitative errors associated with poor SPECT resolution and evaluated the importance of two-dimensional (2D) and three-dimensional (3D) resolution recovery by modelling system response during iterative image reconstruction. METHODS: Different phantoms consisted of the NURBS-based cardiac-torso (NCAT) liver phantom with small tumors, the Zubal brain phantom and the NCAT heart phantom were used in this study. Monte Carlo simulation was used to create SPECT projections. Gaussian functions were used to model collimator detector response (CDR). Modeled CDRs were applied during OSEM. Both noise-free and noisy projections were created. RESULTS: Even with noise-free projections, conventional OSEM algorithm provided limited quantitative accuracy compared to both 2D and 3D resolution recovery. The 3D implementation of resolution recovery, however, yielded superior results compared to its 2D implementation. For the liver phantom, the ability to distinguish small tumors in both transverse and axial planes was improved. For the brain phantom, gray to white matter activity ratio was increased from 3.14 ± 0.04 in simple OSEM to 3.84 ± 0.06 in 3D OSEM. For the NCAT heart phantom, 3D resolution recovery, results in images with thinner wall and higher contrast for different noise levels. CONCLUSION: There are considerable quantitative errors associated with CDR, especially when the size of the target is comparable with the spatial resolution of the system. Between different reconstruction algorithms, 3D OSEM that consider the 3D nature of CDR, improve both the visual quality and the quantitative accuracy of any SPECT studies.

In vivo tracking of 111In-oxine labeled mesenchymal stem cells following infusion in patients with advanced cirrhosis.

BACKGROUND: Several animal and few human studies suggest the beneficial role of bone marrow mesenchymal stem cells (MSCs) in liver cirrhosis. However, little is known about the fate of MSCs after infusion in cirrhotic patients. We evaluated stem cell biodistribution after peripheral infusion of MSCs in four cirrhotic patients. METHODS: After three passages of MSCs, the patients received a total of 250-400×10(6) cells, of which only 50% of the cells were labeled. Specific activities of 0.21-0.67 MBq/10(6) cells were maintained for the injected labeled MSCs. Planar whole-body acquisitions (anterior/posterior projections) were acquired immediately following infusion as well as at 2 h, 4 h, 6 h, 24 h, 48 h, 7th and 10th days after cell infusion. RESULTS: After intravenous infusion, the radioactivity was first observed to accumulate in the lungs. During the following hours to days, the radioactivity gradually increased in the liver and spleen, with spleen uptake exceeding that in the liver in all patients. Region-of-interest analysis showed that the percentage of cells homing to the liver (following decay and background corrections and geometric mean calculation) increased from 0.0%-2.8% at immediately post-infusion images to 13.0-17.4% in 10th-day post-infusion. Similarly, the residual activities in the spleen increased from 2.0%-10.2% at immediately post-infusion images to 30.1%-42.2% in 10th-day post-infusion. During the same period, the residual activities in the lungs decreased from 27.0-33.5% to 2.0-5.4%. CONCLUSION: The infusion of MSCs labeled with (111)In-oxine through a peripheral vein is safe in cirrhosis. Cell labeling with (111)In-oxine is a suitable method for tracking MSC distribution after infusion.

Successful application of technetium-99m-labeled octreotide acetate scintigraphy in the detection of ectopic adrenocorticotropin-producing bronchial carcinoid lung tumor: a case report.

INTRODUCTION: The diagnostic efficacy of somatostatin receptor scintigraphy labeling with 111 indium in the localization of tumors has been assessed in a limited number of patients with contradictory outcomes. Here, we describe the case of a patient with an ectopic adrenocorticotropic hormone-producing bronchial carcinoid tumor diagnosed preoperatively using technetium-99m-labeled octreotide acetate scintigraphy. CASE PRESENTATION: A 29-year-old Asian man presented to our hospital with the typical clinical features of Cushing's syndrome, which he had had for a duration of 18 months. The results of a biochemical evaluation revealed he had adrenocorticotropic hormone-dependent Cushing's syndrome. The results of a spiral abdominal computed tomography scan showed he had bilateral adrenal hypertrophy. A magnetic resonance image of the patient's brain showed he had a normal hypophysis. Whole body technetium-99m-labeled octreotide acetate scintigraphy was performed to check for the presence of an ectopic adrenocorticotropic hormone-producing tumor. The scan results showed a small focal increase in uptake in the lower lobe of our patient's right lung, just above his diaphragm. A spiral chest computed tomography scan also revealed a small non-specific lesion in the same region. A transthoracic biopsy was then performed. Pathological evaluation confirmed the diagnosis of a carcinoid tumor, of the adrenocorticotropic hormone-producing type. After surgical removal, the patient's symptoms resolved and significant clinical improvement was achieved. CONCLUSIONS: This case report shows that technetium-99m-labeled octreotide acetate scintigraphy can effectively detect an ectopic adrenocorticotropic hormone-producing bronchial carcinoid.

Diagnostic role of whole body bone scintigraphy in atypical skeletal tuberculosis resembling multiple metastases: a case report.

INTRODUCTION: Osseous tuberculosis can be present with unifocal or multifocal bony involvement. Although multifocal involvement of the skeletal system in areas where tuberculosis is endemic is not a rare presentation, its exact prevalence is not well known. A case of atypical skeletal tuberculosis mimicking multiple secondary metastases on radiologic and scintigraphic imaging is presented to emphasize the contribution of bone scintigraphy in the assessment of osseous tuberculosis in typical and atypical presentations. CASE PRESENTATION: A 73-year-old cachectic Asian man (Iranian) presented with a general feeling of being unwell and an acute loss of vision in his left eye accompanied by a severe headache. A Tc-99 m-methylene diphosphonate bone scan demonstrated multiple regions of intense activity in the appendicular and axial skeleton, suggesting metastatic involvement. Tumor markers (PSA, CA125, CA 19-9 and AFP) were within normal ranges. Based on clinical presentation and laboratory, radiological and scintigraphic findings, a presumptive diagnosis of tuberculosis was made. Quadruple antituberculous chemotherapy was consequently started and the patient later showed marked improvement. CONCLUSION: Scintigraphic bone scanning should be kept in mind when assessing bone pain in patients at a high risk of tuberculosis infection or reactivation. We present this unusual case of multifocal skeletal tuberculosis, and stress the related clinical and diagnostic points with the aim of stimulating a high index of suspicion that could facilitate early diagnosis and appropriate treatment.

99mTc-MIBI whole body scintigraphy and P-glycoprotein for the prediction of multiple drug resistance in multiple myeloma patients.

Multi-drug resistance (MDR) is a major challenge in the treatment of multiple myeloma (MM). There is low sensitivity of technetium-99m methoxy isobutyl isonitrile ((99m)Tc-MIBI) whole body scan (WBS) in the detection of active MM lesions, because (99m)Tc-MIBI is washed out from malignant cells in the presence of P-glycoprotein (PGP). The objective of the present cohort study was to evaluate of (99m)Tc-MIBI WBS in the prediction of MDR in MM patients during a course of one year follow up. Thirty four patients with MM (25 male, 9 female of mean age 54.12+/-11.46 years) entered the study. Thirteen patients had no previous history of treatment and 21 had a history of previous chemo-radiotherapy. The diagnosis and staging of the disease were based upon routine laboratory and clinical criteria like bone marrow plasma cell count, serum M component, calcium, albumin, beta(2)-microglobulin. Measurements of PGP and WBS using (99m)Tc-MIBI were performed before initialization of treatment and the response to treatment was assessed one year later. The baseline (99m)Tc-MIBI WBS were considered positive for the detection of active lesions when at least one area of non-physiologic increased activity was noted. The follow up (99m)Tc-MIBI WBS was positive for MDR when the patient had active disease but normal WBS. Our results showed that for WBS, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy in active state for the diagnosis of MDR were 38.9%, 62.5%, 70%, 31.2% and 46.1%, respectively. Also the above values for the detection of MDR, using PGP values were 50%, 50%, 69.2%, 30.8% and 50%, respectively. The relative risk of resistant to multiple regimens of chemotherapy after one year follow up in patients with negative to patients with positive (99m)Tc-MIBI WBS was 1.02 (0.60-1.72). In conclusion, we found a low sensitivity of WBS and of PGP in the detection of MDR in patients with active MM. However, both WBS and PGP have 70% and 69% positive predictive value for MDR.

The role of myocardial perfusion imaging in the evaluation of patients undergoing percutaneous transluminal coronary angioplasty.

INTRODUCTION: We studied the value of myocardial perfusion imaging (MPI) for the evaluation of improvement in myocardial perfusion in patients with successful percutaneous transluminal coronary angioplasty (PTCA). METHODS: Sixty patients (10 women, 50 men) aged 54.18 +/- 11.71 years were analyzed. MPI was performed before PTCA, 6-10 days (16 cases), 1-3 months (21 cases), and then 3-6 months (23 cases) after the procedure. In all patients repeated coronary angiography was done at least once after PTCA. Statistical analysis of the numbers of segments with various degrees of perfusion (normal, ischemia, fixed segment), before and after PTCA, was performed for three groups (6-10 days, 1-3 months and 3-6 months after PTCA) separately, using paired T and also ANOVA tests. A p-value <0.05 was considered to be statistically significant. RESULTS: Improvement, defined as a decrease in the number of ischemic or fixed segments, was observed in 13 of 16 patients at 6-10 days after PTCA, in 18 of 21 cases 1-3 months after PTCA, and in 20 of 23 patients 3-6 months after PTCA. The sensitivity and specificity of MPI calculated before PTCA and at the 3 subsequent time points, using angiography as the gold standard, were 80/81, 100/35, 90/100, and 76/100 percent, respectively. CONCLUSION: Our results confirm the necessity for an assessment of perfusion both before and shortly after angioplasty, since it provides the best documentation of the changes in myocardial perfusion.

High accuracy of myocardial perfusion imaging in patients with left bundle branch block: comparison of four interpretation approaches.

Although myocardial perfusion imaging (MPI) with pharmacologic stress is the standard method for screening coronary artery disease (CAD) in patients with left bundle branch block (LBBB), controversies remain about its correct interpretation. We sought the best interpretation approach in these patients to achieve higher accuracy. Forty-two patients with LBBB underwent MPI with dipyridamole stress and the criteria for positive results with four patterns of interpretation were as follows: Pattern A: any reversible or irreversible perfusion abnormality in the myocardium irrespective of the location or extension was considered positive. Pattern B: any reversible or irreversible perfusion abnormalities except in the septal/anteroseptal region were defined as positive. Pattern C: in the absence of fixed LV cavity dilatation, the scan was interpreted the same as pattern A, while in the presence of fixed LV cavity dilatation, only the abnormalities outside the LAD territory was defined as positive. Pattern D: as in pattern C, except that in the absence of fixed LV cavity dilatation, the scan was read according to pattern B. For all patients, the angiographic results were considered as gold standard of CAD diagnosis. Our results showed that the false positive rate of MPI in patients with fixed LV dilatation was 50%, while in cases with normal LV size or transient dilatation, was 38.5%. This difference was more prominent in the female patients. The accuracy for screening CAD for patterns A, B, C and D were 57%, 62%, 69% and 69%, respectively. Pattern D was the better approach in female cases and patients with fixed septal/anteroseptal defects. In conclusion, a) in the male population without fixed defects in the septal/anteroseptal region, the specificity and accuracy are high in all patterns and the pattern of reading does not significantly influence the diagnostic value of MPI for CAD screening. b) in LBBB patients, fixed defects limited to the septal/anteroseptal region should be considered a significant finding only when LV cavity is not dilated.

Detection of splenomegaly on Meckel's diverticulum scan.

A 16-year-old boy was seen with the complaint of intermittent lower gastrointestinal bleeding and was referred for a radionuclide Meckelogram. Although Tc-99m pertechnetate scintigraphy failed to reveal heterotopic gastric mucosa, focal accumulation of radiotracer in a large area involving the left side of the abdomen and liver were seen. Both areas of activity cleared gradually, but the first one remained longer and based on its configuration, raised the possibility of splenomegaly. Further ultrasonographic evaluation confirmed the diagnosis of splenomegaly, which was subsequently determined to be secondary to noncirrhotic portal fibrosis. The findings of radionuclide Meckelograms can be more than detecting heterotopic gastric mucosa.

Radioiodine treatment complications to the mother and child in patients with differentiated thyroid carcinoma.

Radioiodine ((131)I) has been widely used in the treatment of differentiated thyroid carcinoma (DTC). Since radiation can carry a known risk of mutagenic abnormalities, we decided to study the outcome of pregnancy in females with DTC and evaluate the genetic risks and health status of their offspring. We retrospectively studied the medical records of these patients in our Institute from 1999 to 2004. A total of 1110 women were hospitalized for treatment with high doses of (131)I, at least 3700MBq. During this period, 653 of these women were in their reproductive period. A hundred of them who had at least one pregnancy after (131)I treatment, were studied. These women had a total of 126 pregnancies (1-6 pregnancies each) after treatment and 101 pregnancies before treatment. We also reviewed the (131)I dose administered last, as well as the cumulative dose of (131)I. Our results show that the incidence of abortions before (131)I treatment was 16.83% (all were spontaneous abortions) and increased to 26.19% after (131)I treatment (15.87% induced and 10.3% spontaneous abortions). Spontaneous abortions were decreased. There was no significant difference between the mean last (131)I dose and the cumulative dose in patients with or without a history of abortions. Mean interval between the last dose of (131)I treatment and abortions versus the last dose and live child births showed a significant difference. All children had normal birth weight. Three congenital anomalies: Down's syndrome, cardiac abnormalities and macrocephaly were diagnosed. Three episodes of intrauterine death were also recorded. In conclusion, our findings indicate that in women with DTC, treated with high doses of(131)I: a) There was no evidence of increased spontaneous abortions, b) Increasing the interval between the last dose of (131)I treatment and time to pregnancy might be beneficial for decreasing the entire risk of abortions and c) It appears that (131)I treatment had no obvious adverse effects on the risk of congenital anomalies.

The relation between Helicobacter pylori infection and cardiac syndrome X: a preliminary study.

Cardiac syndrome X is defined by an angina pectoris with normal or near normal coronary angiogram.We evaluated the association of Helicobacter pylori (HP) infection with cardiac syndrome X (CSX). We studied 30 patients with CSX, 30 cases with stable angina and also 30 healthy controls. All three groups underwent urea breath test (UBT). Fifty percent (15 out of 30) of CSX patients had positive UBT result (> or =200 dpm), while two other groups did not have the positive results. Regarding high prevalence of HP infection in patients with CSX in our study and probable causative effect of chronic infection in coronary artery diseases, possible role of HP infection in the pathogenesis of CSX is suggested. However well designed clinical trial studies are needed to confirm this preliminary result.

The long term effect of levothyroxine on bone mineral density in patients with well differentiated thyroid carcinoma after treatment.

To date a few studies have focused on the possible effects of subclinical hyperthyroidism on bone metabolism, showing conflicting results. This study was designed to evaluate this possibility. Sixty-six patients, 22 pre-menopausal women, 33 post-menopausal women and 11 men, who had received iodine-131 ((131)I) ablation postoperatively for well differentiated thyroid carcinoma (WDTC) and were treated for a long term with levothyroxine (T(4)), entered the study and were compared with sixty-six healthy controls individually matched to the patients for age, gender and menopausal status. The bone mineral density (BMD) of lumbar and hip regions of the patients was measured, while on the T(4) suppressive treatment, with average duration of 14.93+/-2.17 months after initiation of the T(4) suppressive treatment and was compared with the BMD of healthy controls. All patients were in the subclinical hyperthyroid state, while all controls were serologically and clinically euthyroid. Our results show that there was no significant difference in BMD measured at the lumbar spine of patients and controls in any subgroup (P>0.05). Analysis of the data of BMD from the hips in men, premenopausal women and controls, also revealed no difference. It was noted that the mean BMD of the femur in the postmenopausal women were at the statistical limit of significance as compared to the control group (P=0.05). In conclusion, our findings indicate that the replacement dose of T(4) in WDTC patients after (131)I ablation, does not have a significant effect on BMD in men, in pre and post-menopausal women and hence on the risk of osteoporosis. In post-menopausal women, the mean femoral BMD was at the limit of statistical significance.

Assessment of the accuracy of lacrimal scintigraphy based on a prospective analysis of patients' symptomatology.

BACKGROUND: Dacryoscintigraphy is a noninvasive method frequently used for assessment of the lacrimal drainage system. Sometimes conflicting results with patients' complaints are obtained, which have no clear explanation. In our hypothesis, follow-up of patients evaluated with dacryoscintigraphy could be helpful in determining possible explanations for these conflicting results. METHOD: Thirty-eight consecutive patients (76 eyes) who had not previously undergone dacryocystorhinostomy or probing were entered in the study. Following instillation of 4 MBq (99m)Tc-pertechnetate, a routine procedure of dacryoscintigraphy was performed. After a mean follow-up time of 1.2 +/- 0.3 years (range 0.9-1.6 years), all patients were reassessed clinically. RESULTS: Using initial patients' symptoms as the gold standard, the sensitivity, specificity, NPV, and PPV of dacryoscintigraphy were calculated to be 82.1%, 75%, 60%, and 90.1%, respectively. The kappa value as a measure of agreement was 0.52. Considering the follow-up study as the gold standard, the sensitivity, specificity, NPV, and PPV were calculated as follows, respectively: 96.3%, 90.4%, 96.3%, and 90.4%. The kappa value was 0.86. There were three initially symptom-free eyes with obstructive pattern on the scans, which developed epiphora on the follow-up. In fact, these eyes were initially classified as false positive, but follow-up assessment showed that they were true-positive scans in a subclinical state. CONCLUSION: Despite certain drawbacks inherent to the technique, dacryoscintigraphy provides valuable independent information and allows more accurate management decisions. In some patients, data obtained from lacrimal scintigraphy could be predictive, and it makes possible determination of subclinical nasolacrimal duct obstructions.

Comparison of methods for determination of glomerular filtration rate: low and high-dose Tc-99m-DTPA renography, predicted creatinine clearance method, and plasma sample method.

The gamma camera uptake method with Tc-99m-DTPA (diethylenetriaminepentaacetic acid) is a simple method for determination of glomerular filtration rate (GFR), and is less time-consuming than other methods, but its diagnostic accuracy is debated. Gate's method (low-dose; LD), the high-dose method (HD), the predicted-clearance method, and the plasma-clearance method with Tc-99m-DTPA are compared in this study. We also performed GFR measurement and diuretic renography simultaneously. Tc-99m DTPA renography was performed in 36 patients aged 18-72 years with a wide range of renal function (serum creatinine 1.37 +/- 0.49 mg/dl). GFR was determined by four methods: the gamma camera uptake method with low-dose Tc-99m DTPA (Gates, LD); the gamma camera uptake method with high-dose Tc-99m DTPA (HD); the predicted creatinine clearance method (Cockcroft-Gualt, CG); and the plasma sample clearance (PSC) method using a mono-exponential curve. The PSC method was chosen as reference. The regression equations for the CG, Gates (low-dose), and HD methods against the PSC method were 28.68 + 0.80X (r = 0.72; P value < 0.0001, RMSE = 21.65 ml/min/1.73 m(2)), 6.19 + 0.79X (r = 0.90; P value < 0.0001, RMSE = 10.64 ml/min/1.73 m(2)), and 6.53 + 0.88X (r = 0.93; P value < 0.0001, RMSE = 9.35 ml/min/1.73 m(2)), respectively. In comparison with determination of GFR by the PSC method, the CG method tended to overestimate GFR while, perversely, the LD and HD methods tended to underestimate GFR. The three methods were in agreement with the PSC method but the high-dose GFR method resulted in less error in estimation of GFR. Furthermore, GFR measurement and diuretic renography could be performed at the same time when the high-dose method was used. Because of the low cost and negligible radiation burden, this method might be preferred for routine practice in nuclear medicine.

Single Tc99m Sestamibi injection, double acquisition gated SPECT after stress and during low-dose dobutamine infusion: a new suggested protocol for evaluation of myocardial perfusion.

BACKGROUND: The ability of low dose dobutamine (LDD) has been established in exploiting the reserved contractility of ischemic myocardium. This study was designed to assess the value of a new protocol, with an additional stress imaging during LDD infusion instead of the rest images, for evaluation of coronary artery disease (CAD) and perfusion reversibility. METHODS: A total of 51 patients (42 men, 9 women; 57.2 +/- 11.3 years) were included in the study and underwent three sequential steps of imaging; the first step-stress gated SPECT with Tc-99m sestamibi, immediately followed by the second step-gated SPECT during constant infusion of 7.5 microg/kg/min dobutamine and finally the third step-rest phase scan following trinitroglycerine administration in the next day. The findings were interpreted using the images in three sets of display; first vs. second step-single injection-double acquisition gated SPECT before and during LDD (SIDAGS-LDD), first vs. third step-standard stress/rest protocol, and only first step-gated stress-only SPECT. In all cases, the Visual perfusion index of each protocols were calculated by summating the premeditated 5-point scale (5: normal, 4: completely reversible, 3: partially reversible, 2: nontransmural fixed and 1: transmural fixed defects) of 17 standard myocardial segments. The accuracy as well as the correlation and agreement of protocols for detecting perfusion abnormality and corresponding reversibility were statistically analyzed. RESULTS: Calculated sensitivity, specificity, positive predictive value, negative predictive value and accuracy regarding the presence of CAD in both SIDAGS-LDD and standard protocols were 90.9% (40/44), 71.4% (5/7), 95.2% (40/42), 55.6% (5/9) and 88.2% (45/51), respectively. The extent and localization of perfusion abnormality with the new protocol were correlated well with standard method. The estimation of reversibility, however, was considerably improved by SIDAGS-LDD, especially in those with history of previous myocardial infarction (MI). CONCLUSION: Our proposed protocol demonstrates good correlation and agreement with standard method and even is superior in some cases especially for estimation of viability after MI. Regarding no need for the rest phase radiotracer injection and imaging, this protocol can be more convenient (except the need for close monitoring of the patient during LDD infusion), less time-consuming, less expensive and moreover with less radiation burden to the patients and personnel.

Radio-iodine therapy and Helicobacter pylori infection.

BACKGROUND: Helicobacter pylori is the most important cause of gastritis and related morbidities. Following consumption, radioactive iodine accumulates considerably in the stomach. On the basis of this observation, we decided to determine whether the high radiation induced by radio-iodine in the stomach is effective in the eradication of this infection. METHODS: All consecutive patients with differentiated thyroid carcinoma, who were referred for radio-iodine therapy [dose 117.1 +/- 24.4 mCi (4.3 +/- 0.9 GBq), range 100-200 mCi (3.7-7.4 GBq)], were enrolled. To detect H. pylori infection, the urease breath test (UBT) was performed 1-2 h before radio-iodine consumption and the test was repeated 2 months later. RESULTS: Of 88 patients, 71 had pre-treatment positive UBT. Of these, 23 patients had negative post-treatment result, which means a significant reduction (26.1%, 95% CI 16.8-35.5%) in the number of positive UBT results in our treated population (32.4% of UBT-positive cases became UBT-negative). CONCLUSIONS: Considering the high prevalence of reinfection in developing countries, the therapeutic benefit would have been more considerable if the second UBT had been done with a lag time of less than 2 months. Although radio-iodine therapy is not a logical method for the treatment of patients suffering from H. pylori, our finding provides indirect evidence about the radiosensitivity of bacteria, the future clinical applications of which need to be further evaluated. Also this finding can be useful for the food industry, where radiation is used widely to sterilize food. Regarding the possibility of H. pylori suppression, we recommend not using UBT for screening for the infection for at least within 2 months following radio-iodine therapy.

Quantitative assessment of dacryoscintigraphic images in the evaluation of epiphora.

BACKGROUND: At the present time, only visual analysis is implemented on dacryoscintigraphic images and quantitative assessments are not routinely obtained. The authors have designed a novel, simple, quantitative method for the diagnosis of sac and post-sac obstructions based on the dacryoscintigraphic images. METHOD: Fifty-nine patients with severe unilateral epiphora were included and the contralateral asymptomatic eyes were used as controls. After ocular instillation of 0.1 cc isotonic saline containing 4 MBq 99mTcO4, dynamic images were obtained for 20 minutes. Visual interpretation was done by two blinded specialists in nuclear medicine. A Time-Activity Curve (TAC) was generated for each eye and its pattern was divided to plateau type, shallow-down sloping and deep-down sloping. The excretion ratio (expressed as the percentage of drained activity) in the 2nd, 3rd, 5th, 7th, 10th, 15th and 20th minute of the study was calculated based on the following formula: (the total count in the region of interest (ROI) in the 1st minute - the total ROI count in the 2nd, 3rd, 5th, 7th, 10th, 15th or 20th minute/the total ROI count in the 1st minute) x 100. The results of the quantitative analysis were compared with the clinical symptoms, visual analysis and TAC pattern. RESULTS: At the optimal cut-off points for the 2nd, 3rd, 5th and 7th minute, the sensitivity of the prediction of obstruction was 76%, 72%, 71% and 69%, respectively. The correlation between visual interpretation and the TAC pattern was statistically significant. CONCLUSION: The quantitative evaluation of dacryoscintigraphic images would contribute greatly to achieving an easier and more objective interpretation of the scintigraphic results and also provides a reliable tool for inter-individual comparison and the follow-up of patients. As it is the first time that this innovative method has been examined clinically, it will be necessary to investigate its clinical utility in a larger series of patients.