Elvan Sayit

The role of Tc-99m RBC scintigraphy in the differential diagnosis of orbital cavernous hemangioma

The cavernous hemangioma is the most common benign orbital tumor in adults. Its presentation is during the forth to fifth decades with a slowly progressive unilateral proptosis. Intraconal cavernous hemangiomas may be difficult to differentiate from other intraconal lesions such as schwannomas, meningiomas and hemangiopericytomas. We report a case of orbital cavernous hemangioma diagnosed by Tc-99m RBC scintigraphy. Tc-99m RBC scintigraphy revealed a typical scintigraphic pattern in which there is intense focally increased uptake on the delayed image. We conclude that Tc-99m RBC scintigraphy can be a useful method in the differential diagnosis of orbital cavernous hemangioma as in hepatic hemangioma.

Landau-Kleffner syndrome : Relation of clinical, EEG and Tc-99m-HMPAO brain SPECT findings and improvement in EEG after treatment

Landau-Kleffner syndrome (LKS) is a rare childhood disorder characterized by acquired aphasia with seizures and electroencephalogram (EEG) abnormalities. Tc-99m-HMPAO SPECT was performed in three right handed children with LKS. A relative decrease in perfusion was found in the left temporal cortex of all three patients and also in the left frontoparietal cortex of one patient with hyperkinetic behavior. Degree of regional cerebral perfusion impairment did not correlate with the severity of clinical and EEG abnormalities. Asymmetrical temporoparietal perfusion appears characteristic of LKS. SPECT findings in LKS were evaluated as useful in elucidating the pathogenic features of the disorder in the brain.

Effects of 99mTc-MIBI and 99mTc-MDP administration on dual-energy X-ray absorptiometry bone mineral density measurements.

ObjectiveNuclear medicine procedures are often performed in close-time proximity to bone densitometry studies. The purpose of this study was to determine the effects of 99mTc-hexakis-2-methoxyisobutyl isonitrile (MIBI) and 99mTc-methylene diphosphonate (MDP) on the accuracy of bone mineral density (BMD) measurements performed using dual-energy X-ray density. MethodsThe effect of a diagnostic dose of 99mTc-MIBI on BMD estimations in the lumbar spine and the left total hip was assessed in 30 patients (19 female, 11 male; mean age: 55.5±10.5 years) by using a Lunar DPX-NT scanner. Thirty patients, admitted to the nuclear medicine department for bone scintigraphy (15 female, 15 male; mean age: 56±15.92 years), were included into the study. Each patient underwent dual-energy X-ray density assessment for which a Lunar DPX-NT scanner was used before and 2 h after intravenous injection of 99mTc-MDP (925 MBq) and 99mTc-MIBI (1110 MBq). BMD measurements were calculated from lumbar spine (including L2–4) and left hip (including femoral neck, trochanter, and total hip). For statistical analysis, the Wilcoxon test was used and a P value of less than 0.05 was accepted as statistically significant. ResultsAccording to Wilcoxons statistical test, we found extremely significant changes on the measured BMD, T-score, before and 2 h after the injection of 99mTc-MIBI for lumbar spine and left hip in 30 patients. We found statistically significant decrement on measured BMD from lumbar spine and trochanter before and 2 h after the injection of 99mTc-MDP. Although MDP BMD values in femoral neck and total hip were decreased after the injection of Tc-99m, they did not reach a statistically significant value. The comparison of pre-T-score and post-T-score values showed a statistically significant decrease after the injection for only L2–4 lumbar spine (P = 0.002), but left hip of pre-T-score and post-T-score values did not reach a statistically significant value. ConclusionIn this study, it was determined that measured BMD values are decreased in lumbar spine for all patients. The magnitude of the effect is dependent on the location of the activity. We assume that some radioactivity from 99mTc is counted by the densitometers detector, thus resulting in a decrease in the measured BMD. Scintigraphy and bone densitometry should be performed on different days to avoid artifactual reduction in BMD measurements.

The evaluation of urine activity and external dose rate from patients receiving radioiodine therapy for thyroid cancer

The aim of this study was to determine the external dose rate of iodine retention as a function of time in the bodies of thyroid cancer patients during their isolation period in the hospital. Urine samples were collected at 6th, 12th, 18th, 24th h and 2nd, 3rd, 4th, 5th d from 83 patients after oral administration of (131)I and counted. The external dose rates were also simultaneously determined at the same time points. Then, it was expressed as retained radioiodine body activity versus dose rate. Effective half life calculated from urine sample measurements was found as 18.4±1.8 h within the first 24 h and 64±2.7 h between 48 and 120 h. According to this results, the external dose rate (<20 µSv h(-1)), which patients could be discharged, was achieved after 48 h for 3700 and 5550 MBq, and after 72 h for 7400 MBq of (131)I treatments.

Technetium-99m Hexamethylpropylene Amine Oxime Lung Scintigraphy Findings in Low-Dose Amiodarone Therapy

Amiodarone (AD)-induced pulmonary toxicity is one of the major complications of long-term AD therapy. Technetium-99m-labeled D,L-hexamethylpropylene amine oxime (Tc-99m HMPAO) scintigraphy has been used to assess lung injury. We designed this study to clarify lung uptake changes of Tc-99m HMPAO using low doses of AD (5 mg/kg/day) during long-term therapy in a rabbit model. Group 1 consisted of 7 rabbits fed with AD by gavage for 6 months. To investigate the effect of ketamine on Tc-99m HMPAO uptake, 5 rabbits were included in Group 2 as a control group. Tc-99m HMPAO scintigraphy was performed in both Group 1 and Group 2 at baseline and after 2, 4, 6, 8, and 12 weeks of AD intake. After 16, 20, and 24 weeks of drug intake, Tc-99m HMPAO scintigraphy was repeated only in group 1. One-min anterior images were acquired 30 min after the injection of 37 MBq of Tc-99m HMPAO. For semiquantitative evaluation, the mean count values were obtained and lung/background and liver/background ratios were calculated. Histopathologic evaluation was performed. No increase in lung and liver uptake of Tc-99m HMPAO was found 2, 4, 6, 8, and 12 weeks after drug intake. There was no significant increase in L/B and H/B ratios of Tc-99m HMPAO in Group 1 compared with Group 2. Both scintigraphic studies and histopathologic examinations showed nonspecific changes. Longitudinal studies investigating Tc-99m HMPAO lung uptake may be planned in patients carrying risk factors for AD-induced lung toxicity.

Lung clearance of inhaled 99Tcm-erythromycin lactobionate in non-smokers and smokers

99Tcm-labelled erythromycin lactobionate (99Tcm-EL) was used as a radioaerosol for lung ventilation imaging in humans after animal studies had shown slow clearance of 99Tcm-EL from the alveolar spaces. We performed inhalation studies in 26 volunteers: 11 non-smokers, 13 smokers (3 of whom smoked one cigarette just before inhalation of 99Tcm-EL) and 2 patients with pulmonary emboli (PE). The PE patients were imaged by both 99Tcm-EL and xenon-133 (133Xe) for comparison. The image quality with 99Tcm-EL was comparable to that with 133Xe, showing good peripheral penetration. The biological clearance half-lifes for 99Tcm-EL were 3.9 +/- 1.1 h in the non-smokers, 5.9 +/- 2.2 h in the smokers and 9.8 +/- 6.6 h in the three subjects who smoked a cigarette just before inhalation of the aerosol. 99Tcm-EL was cleared more slowly in the smokers and after smoke exposure, which could have indicated alveolar macrophage uptake. 99Tcm-EL can be used as an alternative to 99Tcm-diethylenetriamine pentaacetate (99Tcm-DTPA) in ventilation imaging, thus overcoming the problem of the fast clearance of 99Tcm-DTPA in smokers.

Comparison of brain perfusion SPECT and MRI findings in children with neuronal ceroid-lipofuscinosis and in their families

Purpose: Neuronal ceroid lipofuscinoses (NCL) are among the progressive encephalopathies of childhood that are inherited in an autosomal recessive manner. In this study we specifically aimed to investigate any white-matter changes in the carriers (parents) and the healthy siblings of individuals with neuronal ceroid lipofuscinosis disease and whether we may be able to predict the occurrence of any neurological symptoms in healthy children in the future thus enabling early management.Materials and Methods: Since the NCLs are genetically determined diseases, we investigated fifteen individuals in three families that had diseased children of the juvenile type, with brain perfusion SPECT and MRI. Brain perfusion SPECT was performed after administering 222–555 MBq (6–15 mCi) Tc-99m HMPAO intravenously in a dimmed and quiet room. Imaging was performed at least one hour after injection, with a three headed gamma camera equipped with high resolution collimators. A Metz filter (FWHM: 11 mm) was used for processing. Cranial MRI was performed with an imager operating at 1.5 Tesla. Spin-echo TI- and T2-weighted and FLAIR slices were obtained for each individual.Results: In all of the five diseased children we observed pathologic findings both on MRI and Tc-99m HMPAO SPECT. The findings on MRI were mainly features of cerebral and cerebellar atrophy and the observations on Tc-99m HMPAO SPECT were regional perfusion abnormalities. We observed some structural abnormalities on MRI in four of the parents and two of the four healthy siblings. We also noted perfusion abnormalities on Tc-99m HMPAO SPECT in two of the parents and two of the healthy siblings.Conclusion: Because the disease is inherited in an autosomal recessive manner, the parents and the healthy siblings were not supposed to exhibit any demonstrable brain lesions, but the brain perfusion SPECT and MRI examinations clearly revealed multiple lesions in some of the parents and healthy siblings. Detailed neurological examinations of these individuals were normal except for one apparently healthy sibling (EY). Follow-up imaging of these families is being undertaken and further studies are essential in understanding the pathogenesis and genetics of neuronal ceroid-lipofuscinoses.

Effect of chemotherapy on pulmonary epithelial permeability in lung cancer

The aim of this study is to investigate the effect of one-course chemotherapy on the pulmonary epithelial permeability. Eighteen patients (18 male; mean age: 59+/-10 years) with lung cancer (11 non-small cell, 7 small cell) inhaled 40 mCi (1,480 MBq) (99m)Tc-diethylenetriaminepentaacetic acid (DTPA). Thirty images of 1-min duration were acquired from posterior projection. The first 7 min of the decay-corrected time activity curves were used to calculate lung clearance half-time. Clearance half-times of (99m)Tc-DTPA from the peripheral regions of the lungs were 42+/-19 min before and 56+/-34 min after chemotherapy (p=0.009); from the central regions, clearance half-times were 112+/-94 min before and 160+/-125 min after chemotherapy (p=0.005). This decrease in clearance rate might be related to decreasing mucociliary clearance rate due to the toxic effect of the chemotherapy regimen on cilia movement and/or mucus structure. (99m)Tc-DTPA radioaerosol study can be used to monitor the toxic effects of chemotherapy on the pulmonary epithelium and possibly on mucociliary function.

Basal and activational 99Tcm-HMPAO brain SPECT in Alzheimer's disease.

Early diagnosis in Alzheimers disease (AD) is important for the administration of new treatments. The purpose of this study was to differentiate mildly/moderately demented AD patients from normal controls by means of activational brain SPECT, and to investigate the correlation between regional cerebral blood flow and dementia severity. Activational brain SPECT was performed 1 week after basal brain SPECT in 12 mild/moderate AD patients according to NINCDS-ADRDA criteria (mean age 69±7 years) and in seven healthy, age-matched, volunteer controls (mean age 65±9 years). In order to activate the parietal cortex, patients were asked to subtract serial 5s from 100, 2 min before and after the intravenous administration of 925 MBq technetium-99m labelled D,L-hexamethyl-propylene amine oxime (99Tcm-HMPAO). Using a three-headed gamma camera equipped with high resolution collimators, 128 images of 35 s duration in a 64×64 matrix were obtained over 360°. Region to whole brain ratios (R/WB) were calculated in three consecutive transaxial slices 2 pixels thick above the orbitomeatal line, and the activation percentage was calculated. No statistical difference was detected between AD patients and normal controls for parietal cortex activation. The correlation coefficient between the Mini-Mental State Examination (MMSE) scoring and the activation percentage was 0.475 in normal controls and 0.175 in AD patients for the left anterior parietal cortex, and 0.353 in normal controls and 0.146 in AD patients for the right anterior parietal cortex. In a visual evaluation of parietal cortex activation, 50% of AD patients were able to activate the parietal cortex, whereas 86% of the normal controls could do so. In our current study, the subtraction of serial 5s was not regarded as a promising task. Further studies are needed to clarify the importance of such tasks in the differential diagnosis of mild/moderate AD patients from normal elderly.

Lung Clearance of Aerosolized 99mTc Erythromycin Lactobionate in Rabbits

In order to assess the lung clearance of aerosolized 99mTc Erythromycin Lactobionate (EL), 99mTc EL was administered to 9 New Zealand rabbits by inhalation. 5 rabbits inhaled cigarette smoke before 99mTc EL. Clearance half times were 3.0 +/- 0.9 hours in normals, 5.5 +/- 1.0 hours after smoke exposure. Clearance was not affected after destroying the surfactant layer. Slower clearance after smoke exposure may be due to the inhibition of mucociliary clearance. 99mTc EL can be considered as an alternative radioaerosol for ventilation imaging.