The role of technetium-99m-HMPAO-labeled WBC scintigraphy in the diagnosis of orbital cellulitis.

Bacterial orbital cellulitis is an infection of the soft tissues behind the orbital septum. Cellulitis is seen as a poorly defined area of increased CT density or T2 signal intensity within the fat. There is an amorphous enhancement following contrast infusion. Radiolabeled leukocytes or granulocytes are now established widely as a means of localizing various forms of inflammatory disease and infections. We report a case of orbital cellulitis detected with Tc-99m-HMPAO-labeled WBC scintigraphy and three-phase bone scintigraphy. Tc-99m-HMPAO-labeled WBC scintigraphy was superior to bone scintigraphy in delineating the extension and limits of the infectious process in the orbita. Tc-99m-HMPAO-labeled WBC scintigraphy is appropriate in the investigation of such infectious lesions, leading to early diagnosis and therapy to avoid severe complications.

Clearance of Tc-99m DTPA aerosol in mismatched and matched pulmonary perfusion defects.

PURPOSE: To evaluate clearance changes of Tc-99m DTPA aerosol in mismatched and matched pulmonary perfusion defects. MATERIALS AND METHODS: Twenty-one patients (14 women, 7 men; mean age, 51 +/- 14 years) with possible pulmonary embolism were included in the study. On the day after perfusion (Q) scintigraphy with 5 mCi Tc-99m MAA, radioaerosol inhalation scintigraphy was performed using 45 mCi Tc-99m DTPA. Immediately and 45 minutes after the inhalation, early and delayed inhalation images (EI and DI, respectively) were obtained. Group 1 included 11 patients with mismatched defects who had a high probability of pulmonary embolism according to the Q/EI scan results. Group 2 included 10 patients with matched defects who had a low probability of PE. Contralateral normal lungs of 7 patients in group 2 served as controls (group 3). In groups 1 and 2, regions of interest were drawn over the mismatched and matched perfusion defects where they were best visualized, and this region of interest was mirrored to the same region on EI and DI images. For the control group, this was done in the contralateral normal lung. Mean counts in each region of interest were used for quantitative analysis, and the percentage clearance ratio was calculated using the following formula: early counts - late counts/early counts x 100. RESULTS: The average percentage clearances for the three groups were as follows: group 1, 37% +/- 10%; group 2, 21% +/- 4%; group 3, 24% +/- 7%. Differences between groups 1 and 3 were significant, as were those between groups 1 and 2 (P < 0.05). Patients with mismatched perfusion defects had increased DTPA clearance compared with the control group and those with matched defects. CONCLUSIONS: Vascular occlusion may lead to impairment of the alveolar-capillary barrier and consequently an increase in the clearance of Tc-99m DTPA aerosol in embolized regions. Immediately after inhalation, Tc-99m DTPA imaging should be started in the projection where perfusion defects are best seen to avoid potential misinterpretation of pulmonary embolism.

Effects of octreotide and morphine on the clearance rate of indium-111-pentetreotide from the epidural space.

In this study we aimed to evaluate the possible mechanisms by which somatostatin acts when given epidurally. Twenty male New Zealand rabbits were randomly separated into four groups and various drugs were administered via a caudal epidural catheter. Group 1 received a bolus of 3.7 MBq indium-111 ((111)In)-pentetreotide, group 2 received 200 microg octreotide and after 15 min a bolus of 3.7 MBq (111)In-pentetreotide, group 3 received 0.1 mg morphine and after 15 min a bolus of 3.7 MBq (111)In-pentetreotide, and group 4 received a bolus of 3.7 MBq technetium-99m (99Tc(m))-diethylene triamine pentaacetic acid (DTPA). Dynamic images of 60 min' duration were obtained from the posterior projection. T(1/2), fast and T(1/2) total clearance half-times were calculated. When unlabelled octreotide was given to block somatostatin receptors, clearance of (111)In-pentetreotide was found to be faster. Epidural morphine administration did not change the clearance rate of (111)In-pentetreotide. All these findings are in favour of octreotide binding to its probable own specific receptors present in the epidural space.

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 Alzheimer's 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 5's 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 x 64 matrix were obtained over 360 degrees. 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 5's 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.

Effects of haemodialysis on pulmonary clearance of Tc-99m diethylene triamine pentaacetate (DTPA).

OBJECTIVES: Hypoxaemia occurring during haemodialysis has long been known. Several mechanisms in the pathogenesis have been proposed. The present study was conducted to test whether changes in pulmonary alveolar permeability were among the operating mechanisms. MATERIALS AND METHODS: Twenty haemodialysis patients (12 male, 8 female) were included in the study. The mean age was 49 years (age range: 18-85 years). Patients with known pulmonary disease, current smokers and those gaining more than 1 kg weight during the interdialytic period were excluded. Complete blood count, arterial blood gas analysis, pulmonary function tests and Tc-99m diethylene triamine pentaacetate (DTPA) inhalation scintiscan were carried out before and after haemodialysis. A bronchial provocation test was carried out after each session. A postero-anterior chest radiogram was taken for each patient. RESULTS: When the results before and after haemodialysis were compared, it was observed that the pH and serum bicarbonate levels, haemoglobin and haematocrit values were significantly higher after haemodialysis. However, the platelet count was found to be decreased significantly. Bronchial hyperreactivity, tested by metacholine, Was positive in 5 of 19 patients (26%). No correlation between bronchial hyperreactivity and other factors could be identified. No significant difference was observed in pulmonary Tc-99m DTPA clearance after haemodialysis. All chest radiograms were interpreted to be within normal limits. CONCLUSIONS: Since we observed no hypoxaemia following haemodialysis, we cannot comment as to whether the changes in pulmonary clearance play a role in the pathogenesis of haemodialysis-associated hypoxaemia. In order to reach reliable conclusions, additional studies are needed.

Detection of bilateral multifocal breast cancer using Tc-99m sestamibi imaging. The role of delayed imaging.

PURPOSE: Early determination that breast cancer is bilateral and multifocal can change therapy strategy and, subsequently, mortality and morbidity rates. The authors present a case with bilateral, multifocal breast cancer detected only by Tc-99m sestamibi imaging. METHODS: Early and delayed Tc-99m sestamibi imaging and dynamic MRI were performed in a patient with a right-sided lesion shown on mammography. RESULTS: Although early Tc-99m sestamibi imaging detected bilateral breast cancer foci, both dynamic MRI and mammography missed the lesion in the left breast. Additional lesions seen on delayed Tc-99m sestamibi images of the left breast, which were initially thought to be benign, completely disappeared after concomitant chemotherapy and radiotherapy, suggesting multifocal malignant lesions in the left breast. CONCLUSION: This case suggests that Tc-99m sestamibi may be useful for detecting bilateral cancer, and delayed imaging may give additional information regarding the possible multifocal nature of the disease.

Technetium-99m-tetrofosmin scintigraphy in pulmonary tuberculosis.

UNLABELLED: Technetium-99m-tetrofosmin, an agent that is widely used in myocardial imaging, has been reported to accumulate in several types of malignancies, including lung tumors. Yet, there is limited knowledge about its role in imaging infection or inflammatory lesions. The aim of this study was to investigate the role of 99mTc-tetrofosmin scintigraphy in pulmonary tuberculosis in cases with active and inactive tuberculosis in comparison with radiological and microbiological findings. METHODS: Twenty-seven patients with active pulmonary tuberculosis (APTB) and 6 patients with inactive pulmonary tuberculosis (IPTB), proven by sputum smears and cultures, were included in this study. Mean age of the group was 42.6+/-13 yr. Nine months after therapy, 99mTc-tetrofosmin scintigraphy was repeated in 6 patients with APTB to evaluate response to therapy. Ten-minute anterior and posterior chest images were acquired 20 and 60 min after the injection of 370 MBq (10 mCi) 99mTc-tetrofosmin. The images were evaluated both visually and semiquantitatively by two blinded nuclear medicine physicians. For semiquantitative evaluation, regions of interest (ROIs) were drawn over the lesion (L) and nonlesion areas (NL). The mean count values of ROIs were obtained and L/NL ratios were calculated. RESULTS: According to the visual evaluations, 99mTc-tetrofosmin uptake was Grade (+) in 4 (15%) and Grade (++) in 23 (85%) patients with APTB. Technetium-99m-tetrofosmin uptake was negative in 5 patients with IPTB. Grade (+) 99mTc-tetrofosmin uptake was observed in only one inactive case. After therapy, there was no 99mTc-tetrofosmin uptake in 3 patients, which correlated well with chest radiography and clinical findings. In the other 2 patients, 99mTc-tetrofosmin uptake was slightly decreased when compared with a previous scan that correlated with radiological and clinical findings. In 1 patient with bilateral lung disease, 99mTc-tetrofosmin uptake decreased on the right lung lesions, whereas the left lung lesions persisted with no change. The mean early and delayed L/NL ratios of APTB were 1.53+/-0.22 and 1.45+/-0.21, respectively. Although 99mTc-tetrofosmin uptake in APTB lesions was more visually marked in early images than that in delayed images, there was no statistically significant difference between these two sets of images. CONCLUSION: Technetium-99m-tetrofosmin scintigraphy showed increased uptake in APTB lesions related to disease activity. After treatment, 99mTc-tetrofosmin uptake disappeared or decreased, correlating well with radiological and clinical findings. Technetium-99m-tetrofosmin scintigraphy may have a complementary role in the assessment of APTB as well as in follow-up treatment.

Infusion versus bolus injection of Tc-99m tetrofosmin in the identification of viable myocardium.

In this report, a patient with 100% RCA stenosis and prominent collaterals, in which TI-201 rest/redistribution and Tc-99m tetrofosmin infusion imaging findings were compatible with viable myocardium in contrast to Tc-99m tetrofosmin bolus imaging is presented. Viability was confirmed with improvement of wall motion and perfusion 3 months after revascularization. Infusion of Tc-99m tetrofosmin rather than a bolus injection may be a more reliable technique in the identification of severely ischemic but viable myocardium.

Sublingual nitrate plus 99Tcm-tetrofosmin infusion in the detection of severely ischaemic but viable myocardium: a comparative study with stress, redistribution, reinjection and late redistribution 201Tl imaging.

To investigate the role of sublingual nitrate plus 99Tcm-tetrofosmin infusion in the detection of severely ischaemic but viable myocardium, we selected 25 patients with coronary artery disease who had at least one fixed segmental defect during conventional stress-redistribution (ST-RD) 201Tl single photon emission tomographic (SPET) imaging. Reinjection (RI) and 24 h late redistribution (LRD) imaging were also performed. Within a week of 201Tl imaging, one-day rest-stress (R-ST) 99Tcm-tetrofosmin SPET was performed with the same stress levels. The following day, 99Tcm-tetrofosmin was infused over 1 h immediately after sublingual nitrate administration and SPET images (N + Inf) were acquired. Of 100 fixed defects on R-ST 99Tcm-tetrofosmin imaging, 15 were reversible on N + Inf 99Tcm-tetrofosmin imaging. There was 91% concordance between ST-RD/RI/LRD 201Tl and R-ST/N + Inf 99Tcm-tetrofosmin imaging regarding reversibility. We conclude that N + Inf 99Tcm-tetrofosmin imaging may be clinically useful in the detection of severely ischaemic but viable myocardium.