Investigated geometrical characteristics and image density of left ventricle of multi-detector computed tomography in early coronary artery disease patients.

BACKGROUND: Coronary artery disease (CAD) remains the leading cause of death worldwide. Currently, cardiac multi-detector computed tomography (MDCT) is widely used to diagnose CAD. The purpose in this study is to identify informative and useful predictors from left ventricular (LV) in the early CAD patients using cardiac MDCT images. MATERIALS AND METHODS: Study groups comprised 42 subjects who underwent a screening health examination, including laboratory testing and cardiac angiography by 64-slice MDCT angiography. Two geometrical characteristics and one image density were defined as shape, size and stiffness on MDCT image. The t-test, logistic regression, and receiver operating characteristic curve were applied to assess and identify the significant predictors. The Kappa statistics was used to exam the agreements with physician's judgments (i.e., Golden of True, GOT). RESULTS: The proposed three characteristics of LV MDCT images are important predictors and risk factors for the early CAD patients. These predictors present over 80% of AUC and higher odds ratio. The Kappa statistics was 0.68 for the combinations of shape and stiffness into logistic regression. CONCLUSIONS: The shape, size and stiffness of the left ventricular on MDCT can be used to be the effective indicators in the early CAD patients. Besides, the combinations of shape and stiffness into logistic regression could provide substantial agreement with physician's judgments.

Ir-192 Calibration in Air with Farmer Chamber for HDR Brachytherapy.

A comprehensive review for the in-air calibration of an Ir-192 high-dose-rate brachytherapy source in terms of air kerma strength (AKS) and reference air kerma rate (RAKR) using the Farmer chamber was conducted. The reviewed calibration methods include the National Physical Laboratory (NPL) calibration standard in the UK, the 7-distance technique with the standard calibration of the National Institute of Standards and Technology and Accredited Dosimetry Calibration Laboratory in the US, the calibration conducted in Australia following recommendations of the International Atomic Energy Agency with the chamber primarily calibrated by the Australian Radiation Protection and Nuclear Safety Agency, the calibration conducted in India following the Deutsche Gesellschaft fur Medizinische Physik recommendation, and the convenient empirical method used in Taiwan. The calibrated AKS (or RAKR) and uncertainty obtained using Farmer chambers are similar to those obtained using well chambers. All reported differences (between measurements obtained using Farmer and well chambers, respectively) and uncertainties (k = 2) were generally less than 1.5 and 2.5 %, respectively. The standard uncertainty of the NPL calibration is approximately half that of all the other proposed approaches, and may become the gold standard calibration procedure. Almost all techniques follow the 7-distance technique basis; however, the services at NPL can calibrate the source with lower uncertainty. Users can calibrate the Ir-192 source more conveniently using the empirical method with only one source-chamber distance.

Analyzing coronary artery disease in patients with low CAC scores by 64-slice MDCT.

PURPOSE: Coronary artery calcification (CAC) scores are widely used to determine risk for Coronary Artery Disease (CAD). A CAC score does not have the diagnostic accuracy needed for CAD. This work uses a novel efficient approach to predict CAD in patients with low CAC scores. MATERIALS AND METHODS: The study group comprised 86 subjects who underwent a screening health examination, including laboratory testing, CAC scanning, and cardiac angiography by 64-slice multidetector computed tomographic angiography. Eleven physiological variables and three personal parameters were investigated in proposed model. Logistic regression was applied to assess the sensitivity, specificity, and accuracy of when using individual variables and CAC score. Meta-analysis combined physiological and personal parameters by logistic regression. RESULTS: The diagnostic sensitivity of the CAC score was 14.3% when the CAC score was ≤30. Sensitivity increased to 57.13% using the proposed model. The statistically significant variables, based on beta values and P values, were family history, LDL-c, blood pressure, HDL-c, age, triglyceride, and cholesterol. CONCLUSIONS: The CAC score has low negative predictive value for CAD. This work applied a novel prediction method that uses patient information, including physiological and society parameters. The proposed method increases the accuracy of CAC score for predicting CAD.

Detection of gastroesophageal reflux esophagitis using 2-fluoro-2-deoxy-d-glucose positron emission tomography.

BACKGROUND: Gastroesophageal reflux disease (GERD) is a common disease and a major upper gastrointestinal problem. The purpose of the present study is to evaluate the use of noninvasive 2-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) to detect gastroesophageal reflux esophagitis. MATERIALS AND METHODS: This is a retrospective study reviewing 408 healthy check-up subjects (169 females and 239 men), who underwent both FDG-PET and upper gastrointestinal endoscopy during September 2008 to December 2009. Quantitative analysis of FDG uptake in the distal part of the esophagus was performed by calculating the maximum standard uptake value (SUVmax). This indicated the degree of esophagitis. FDG-PET findings were compared with endoscopic (modified version of the Los Angeles classification) diagnoses as the gold standard. RESULTS: The SUVmax ranged from 1.30 to 3.40 in normal subjects and from 1.30 to 4.00 in subjects with gastroesophageal reflux esophagitis. In the esophagitis group, the SUVmax was 2.13 ± 0.42 in subjects with modified LA grade M, 2.21 ± 0.45 in subjects with LA grade A, and 2.48 ± 0.44 in subjects with LA grade B and C gastroesophageal reflux esophagitis. One-way ANOVA and post-hoc comparison with Bonferroni correction (P value = 0.003) identified statistical differences between the three groups. CONCLUSION: Noninvasive FDG-PET may be useful in the detection and evaluation of various degrees of gastroesophageal reflux esophagitis.

Calibration of the EBT3 Gafchromic Film Using HNN Deep Learning.

To achieve a dose distribution conformal to the target volume while sparing normal tissues, intensity modulation with steep dose gradient is used for treatment planning. To successfully deliver such treatment, high spatial and dosimetric accuracy are crucial and need to be verified. With high 2D dosimetry resolution and a self-development property, the Ashland Inc. product EBT3 Gafchromic film is a widely used quality assurance tool designed especially for this. However, the film should be recalibrated each quarter due to the "aging effect," and calibration uncertainties always exist between individual films even in the same lot. Recently, artificial neural networks (ANN) are applied to many fields. If a physicist can collect the calibration data, it could be accumulated to be a substantial ANN data input used for film calibration. We therefore use the Keras functional Application Program Interface to build a hierarchical neural network (HNN), with the inputs of net optical densities, pixel values, and inverse transmittances to reveal the delivered dose and train the neural network with deep learning. For comparison, the film dose calculated using red-channel net optical density with power function fitting was performed and taken as a conventional method. The results show that the percentage error of the film dose using the HNN method is less than 4% for the aging effect verification test and less than 4.5% for the intralot variation test; in contrast, the conventional method could yield errors higher than 10% and 7%, respectively. This HNN method to calibrate the EBT film could be further improved by adding training data or adjusting the HNN structure. The model could help physicists spend less calibration time and reduce film usage.

Calibration of Gafchromic EBT Film Using the Microtek ScanMaker 9800XL Plus Flatbed Scanner with a Modified One Red-Channel after Three-Channel Method.

PURPOSE: Using the Microtek ScanMaker 9800XL Plus (9800XL+) flatbed scanner, a method is presented to accurately calibrate EBT film, which cannot be calibrated simply using a general three-channel method because of the nonhomogeneous scanning. MATERIALS AND METHODS: Through the percentage-depth-dose method, 6-MV photon beams with two different monitor units were delivered to eight EBT2 films, each of which was tightly sandwiched in a 30-cm cubic polystyrene phantom and positioned parallel to the central axis of the beam. Before and after irradiation, all films were scanned using the Microtek 9800XL+ scanner and the pixel values (PVs) were measured along the central axis of the beam on the film and fitted to the corresponding depth doses. Before calibration, the irradiated film image was first modified using a template matrix, which was generated using the prescanned background images. Then, a modified one red-channel after three-channel method was used to calibrate the film. RESULTS: Without a template matrix, the three-channel method cannot be used because the PVs do not correspond to a rational fitting form. Using the proposed method, the difference between the fitted dose and the delivered dose is <2%. The green channel, and not the red, is found to have the largest dynamic range. CONCLUSION: The proposed technique allows the use of the three-channel method to calibrate film using a Microtek 9800XL+ scanner.

F-18 FDG PET in detecting uterine leiomyoma.

PURPOSE: Uterine leiomyoma, benign tumors of the human uterus, are clinically apparent in about 25% of women and the most common solid pelvic tumors. The purpose of this study was to investigate the F-18 2-fluoro-2-deoxy-D-glucose (FDG) uptake in the uterine leiomyoma and assess the correlation between the intensity of FDG uptake in the uterine leiomyomas and menstrual cycle. METHODS: A total of 589 charts of healthy females examined by whole body FDG positron emission tomography (PET) for health screening examination were reviewed retrospectively. Twenty-two of them were suspected gynacecological tumors and referred to the department of gynacecology to ascertain the nature of the causes. Final diagnosis as uterine leiomyomas were made based on uterine sonography, pelvic computed tomography, or pelvic magnetic resonance imaging scans. We defined FDG uptake as Grade I when FDG uptake was less than liver uptake, Grade II when FDG uptake was equal to liver uptake, and Grade III when FDG uptake was greater than liver uptake. The menstrual cycle was recorded on the day of performing FDG PET in premenopausal women. RESULTS: The FDG uptake in the uterine region is Grade I in three of these 22 females (13.65%), Grade II in 16 (72.7%), and Grade III in 3 (13.65%). CONCLUSION: There is no significant correlation between the intensity of FDG uptake in the uterine leiomyomas and menstrual cycle (P=.914).

Correlation between the intensity of breast FDG uptake and menstrual cycle.

RATIONALE AND OBJECTIVES: [18F]fluorodeoxyglucose positron emission tomography (F-18 FDG PET), a functional imaging modality has opened a new field in clinical imaging that informs about glucose metabolism of tissues. However, increased FDG uptake is not limited to malignant tissues alone. We hypothesize that the intensity of physical FDG uptake in the normal breast tissues would affect the detect ability of breast cancer; therefore, good knowledge of physical FDG uptake in the healthy population is important for the correct interpretation of FDG PET images of pathologic processes. The study aimed to evaluate the relationship between intensity of FDG uptake in the normal breast tissues and menstrual cycle. MATERIALS AND METHODS: A total of 1,108 charts of healthy females, referred from the department of family medicine of China Medical University Hospital, examined by whole-body FDG PET for health screening examination between June 2002 and June 2006 were reviewed retrospectively and included for analyzing. A total of 524 premenopausal females with regular menstrual cycles over the previous 6 months (length 26-30 days) and 584 menopausal females without current use of exogenous hormones were included in this study. The menstrual cycle was recorded on the day of performing FDG PET in premenopausal women. The breast tissues are diagnosed as normal either by mammary sonography or by mammography. We defined FDG uptake was Grade I when FDG uptake was equal to the pulmonary uptake, Grade II when FDG uptake between pulmonary and liver uptake, and Grade III when FDG uptake equal to or greater than liver uptake. RESULTS: The FDG uptake in the breast regions shows Grade I in 500 women (45.1%), Grade II in 281 (25.4%) and Grade III in 327 (29.5%). Among the Grade I uptake group, 388 are menopausal, 1 is in flow phase, and 111 are in proliferative phase. Among the Grade II uptake group, 196 are menopausal, 23 are in flow phase, 9 are in proliferative phase, 43 are in the ovulatory phase, and 10 are in the secretory phase. Among Grade III uptake group, 97 are in flow phase, 108 are in the ovulatory phase, and 122 in the secretory phase. The study shows significant correlation between the intensity FDG uptake in the normal breast tissues and menstrual cycle (P < .001). CONCLUSIONS: The physical FDG uptake in the normal breast tissues is generally homogeneous. There is no Grade III FDG uptake in the normal breast tissues in menopause women without using exogenous hormones or in proliferative phase women. In addition, there is no Grade I FDG uptake in the normal breast tissues in the ovulatory phase or secretory phase women.

Clinical usefulness of fused PET/CT compared with PET alone or CT alone in nasopharyngeal carcinoma patients.

UNLABELLED: The diagnostic accuracy of fused positron emission tomography/computed tomography (PET/CT) was compared with CT alone and PET alone in the staging and re-staging of nasopharyngeal carcinoma (NPC) patients. PATIENTS AND METHODS: Eighty-six fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) PET/CT studies were retrospectively performed in 70 patients with NPC, 20 patients for primary tumor staging and 50 patients for re-staging after treatment. Each lesion was analyzed visually and assigned a score on a 5-point scale. Each study was interpreted in 3 ways: PET images were evaluated in the absence of CT data, CT images in the absence of PET data and fused PET/CT images. The results of these images were correlated with histological findings, as well as long-term radiological and clinical follow-up (the shortest follow-up period after imaging was 6 months). PET, CT and PET/CT accuracy were compared by a McNemar test. RESULTS: Fused PET/CT correctly characterized the tumor-node-metastasis system stage in 82 out of 86 studies (95.4%; 95% CI: 90.9% to 99.9%). PET alone and CT alone were found to be accurate in 71 out of 86 studies (82.6%; 95% CI: 74.5% to 90.6%) and 63 out of 86 studies (73.3%; 95% CI: 63.9% to 82.6%), respectively. Furthermore, the differences between PET/CT and either PET alone or CT alone were statistically significant (p<0.05). Overall, the study-based analysis of PET/CT for staging NPC demonstrated 48 true-positive, 2 false-negative, 34 true-negative and 2 false-positive studies. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of FDG-PET/CT studies for staging NPC were 96%, 94.4%, 95.4%, 96% and 94.4%, respectively. CONCLUSION: PET/CT is more accurate than PET alone or CT alone for the depiction of NPC. Fused PET/CT is a valuable imaging tool in patients for staging diagnosis of NPC.

Positive correlation between standardized uptake values of FDG uptake in the stomach and the value of the C-13 urea breath test.

PURPOSE: The distribution of FDG uptake in the stomach is variable. Gastritis is one of the causes of elevated FDG uptake. Helicobacter pylori (HP) infection was found in approximately 80% of patients with peptic ulcer and 30% to 60% of symptomatic gastritis. The C-13 urea breath test (UBT) is one of the gold standard tools in diagnosis of HP infection. The aim of this study was to assess the correlation between standardized uptake values (SUVs) of FDG uptake in the stomach and the value of the C-13 urea breath test (UBT). METHODS: Sixteen patients, referred from the department of community medicine, for FDG PET for health examination were chronologically enrolled for detection of HP infection by using the C-13 UBT within 1 week. The maximal SUVs of FDG uptake in the gastric wall as well as the value of the C-13 UBT were measured. The correlation between maximal SUVs of FDG uptake in the stomach and the value of the C-13 UBT was observed. RESULTS: We took the results of C-13 UBT as the final diagnosis of HP infection. Of 16 patients, 5 were HP-infected and 11 were uninfected. Standardized uptake values of FDG uptake in the gastric wall were strong positively correlated with the value of the C-13 UBT in this retrospective study (P < 0.001). CONCLUSION: Except for gastric cancer, HP infection has to be concerned when high SUVs of FDG uptake in the stomach are noted.

A novel loss-of-function deletion in sodium/iodide symporter gene in follicular thyroid adenoma.

The sodium/iodide symporter (NIS) actively transports iodide into thyrocytes. However, in thyroid carcinoma, down-regulated or mis-targeted NIS expression is commonly found and usually correlates with tumor dedifferentiation and loss of radioiodine uptake capacity. In this study, we screened NIS genes of thyroid tumor tissues from three patients with thyroid carcinoma by using reverse transcription-polymerase chain reaction and nucleotide sequencing. We found a novel exon 6 deletion in NIS gene. We then examined the NIS gene from the blood of this patient. The nucleotide sequences of the flanking region of exon 6 were normal. By transient transfection and I-125 uptake assay, we found that the wild type NIS-expressing HepG2 cells accumulated six times more iodide than mutant and mock HepG2 cells. Our data demonstrated that the exon 6 deletion causes an iodide-trapping defect.

Prevalence and risk of cancer of focal thyroid incidentaloma identified by 18F-fluorodeoxyglucose positron emission tomography for cancer screening in healthy subjects.

The aim of this study was to define the clinical prevalence and rate of malignancy of focal thyroid incidentaloma in a relatively large number of individuals with application of 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) in asymptomatic individuals. The subjects consisted of 4803 physical check-up examinees (2638 men, 2165 women; mean age+/-SD, 52.8+/-9 years old) with non-specific medical history. Whole-body FDG PET was performed on all patients. Focal hypermetabolic areas of thyroid, with an intensity equal to or exceeding the level of FDG uptake in the liver, were considered abnormal and interpreted as thyroid incidentaloma. Among the 4803 FDG PET examinations, thyroid incidentaloma was present in 60 examinations, among which, 50 had further examination with ultrasound-guided fine-needle aspiration (FNA), revealing 43 benign lesions and 7 papillary carcinomas. Of 7 examinees diagnosed with cancer, 2 had lymph nodes metastasis. The mean and standard deviation of standard uptake value (SUV) in benign and carcinoma was 2.6+/-1.01 and 6.7+/-3.66, respectively. Thyroid incidentaloma identified by FDG-PET occurred with a frequency of 1.2% (60/4803). Of the thyroid incidentalomas that underwent FNA and surgery, 14% (7/50) were found to be malignant. It is possible to differentiate benign from carcinoma of thyroid incidentalomas by the increased rate of glycolysis (SUV) in the carcinoma. The small size and moderate FDG uptake of thyroid incidentalomas per se cannot guarantee low risk in incidentally found thyroid cancers.

Calibration of EBT2 film using a red-channel PDD method in combination with a modified three-channel technique.

PURPOSE: Ashland Inc. EBT2 and EBT3 films are widely used in quality assurance for radiation therapy; however, there remains a relatively high degree of uncertainty [B. Hartmann, M. Martisikova, and O. Jakel, "Homogeneity of Gafchromic EBT2 film," Med. Phys. 37, 1753-1756 (2010)]. Micke et al. (2011) recently improved the spatial homogeneity using all color channels of a flatbed scanner; however, van Hoof et al. (2012) pointed out that the corrected nonuniformity still requires further investigation for larger fields. To reduce the calibration errors and the uncertainty, the authors propose a new red-channel percentage-depth-dose method in combination with a modified three-channel technique. METHODS: For the ease of comparison, the EBT2 film image used in the authors' previous study (2012) was reanalyzed using different approaches. Photon beams of 6-MV were delivered to two different films at two different beam on times, resulting in the absorption doses of ranging from approximately 30 to 300 cGy at the vertical midline of the film, which was set to be coincident with the central axis of the beam. The film was tightly sandwiched in a 30(3)-cm(3) polystyrene phantom, and the pixel values for red, green, and blue channels were extracted from 234 points on the central axis of the beam and compared with the corresponding depth doses. The film was first calibrated using the multichannel method proposed by Micke et al. (2010), accounting for nonuniformities in the scanner. After eliminating the scanner and dose-independent nonuniformities, the film was recalibrated via the dose-dependent optical density of the red channel and fitted to a power function. This calibration was verified via comparisons of the dose profiles extracted from the films, where three were exposed to a 60° physical wedge field and three were exposed to composite fields, and all of which were measured in a water phantom. A correction for optical attenuation was implemented, and treatment plans of intensity modulated radiation therapy and volumetric modulated arc therapy were evaluated. RESULTS: The method described here demonstrated improved accuracy with reduced uncertainty. The relative error compared with the measurements of a water phantom was less than 1%, and the overall calibration uncertainty was less than 2%. Verification tests revealed that the results were close to those of the authors' previous study, and all differences were within 3%, except those with a high-dose gradient. The gamma pass rates (2%/2 mm) of the treatment plan evaluated using the method described here were greater than 99%, and no obvious stripe patterns were observed in the dose-difference maps. CONCLUSIONS: Spatial homogeneity was significantly improved via the calibration method described here. This technique is both convenient and time-efficient because it does not require cutting the film, and only two exposures are necessary.

Application of PET and PEt/CT imaging for cancer screening.

The aim of this study was to evaluate the potential application of 18-fluorodeoxyglucose positron emission tomography (FDG PET) and PET/CT for cancer screening in asymptomatic individuals. The subjects consisted of 3631 physical check-up examinees (1947 men, 1684 women; mean age +/- SD, 52.1 +/- 8.2 y) with non-specific medical histories. Whole-body FDG PET (or PET/CT), ultrasound and tumor markers were performed on all patients. Focal hypermetabolic areas with intensities equal to or exceeding the level of FDG uptake in the brain were considered abnormal and interpreted as neoplasia. Follow-up periods were longer than one year. Among the 3631 FDG PET (including 1687 PET/CT), ultrasound and tumor markers examinations, malignant tumors were discovered in 47 examinees (1.29%). PET findings were true-positive in 38 of the 47 cancers (80.9%). In addition, 32 of the 47 cancers were screened with the PET/CT scan. PET detected cancer lesions in 28 of the 32 examinees. However, the CT detected cancer lesions in only 15 out of 32 examinees. The sensitivity of FDG PET in the detection of a wide variety of cancers is high. Most cancer can be detected with FDG PET at a resectable stage. CT of the PET/CT for localization and characteristics of the lesion showed an increased specificity of the PET scan. The use of ultrasound and tumor markers may complement the PET scan in cancer screening for hepatic and urologic neoplasms.

Usefulness of thallium-201 muscle perfusion scan to investigate perfusion reserve in the lower limbs of Type 2 diabetic patients.

This study evaluated the usefulness of thallium-201 muscle perfusion scan (Tl-201 muscle scan) to investigate perfusion reserve in the lower limbs of asymptomatic Type 2 diabetic patients without peripheral ischemia findings. Tl-201 muscle scan was carried out in 36 diabetic male patients with Type 2 diabetes mellitus of more than 10 years in duration who had no evidence of peripheral arterial disease in their history, physical examination, or Doppler ultrasonography. A control group consisted of 24 healthy age-matched nondiabetic men. Each subject flexed their right foot maximally both dorsally and plantar 60 times. In the middle of this exercise, 2mCi Tl-201 was injected intravenously. Three minutes after the injection, a posterior image of both calves was obtained using a gamma camera. Rectangular regions of interest (ROIs) were symmetrically drawn over both calves. The total count (Ct) in the resting calf was subtracted from the Ct in the exercising calf, and the percentage increase, termed the perfusion reserve, was determined. A significant difference was found between the perfusion reserves of the Type 2 diabetic patients and control groups (70.2+/-10.7% and 98.6+/-9.4%, respectively; P<.05). In conclusion, the perfusion reserve in the lower limb muscles in Type 2 diabetic patients may be measured by Tl-201 muscle perfusion scan.

High prevalence of asymptomatically poor muscle perfusion of lower extremities measured in type II diabetes patients with abnormal myocardial perfusion.

Foot problems are the most common cause of hospital admission in patients with type II diabetes mellitus (DM). Poor muscle perfusion of lower extremities is thought to be the major component in the pathogenesis of foot problems. Therefore, it is important and interesting to investigate if high prevalence of poor muscle perfusion of lower extremities in type II DM patients with abnormal myocardial perfusion and more cardiovascular risk factors. We used a well-established and noninvasive radionuclide method (Xe-133 muscle washout) to objectively evaluate the anterior tibial muscle perfusion of 60 type II DM male patients without symptoms/signs of peripheral vascular disease (PVD) in the lower extremities. The patients were separated into groups according to the myocardial perfusion imaging results and cardiovascular risk factor survey. Meanwhile, 30 normal male controls with a matched age distribution were also included for comparison. The muscle perfusions were of significant difference (P-values <.05) between (1) 60 type II DM patients (1.84+/-0.43 ml/100 g/min) and 30 normal controls (2.95+/-0.52 ml/100 g/min), (2) 24 patients with abnormal myocardial perfusion (1.31+/-0.45 ml/100 g/min) and 36 patients with normal myocardial perfusion (2.24+/-0.48 ml/100 g/min), as well as (3) 28 patients with more cardiovascular risk factors (1.33+/-0.46 ml/100 g/min) and 22 patient with less cardiovascular risk factors (2.22+/-0.49 ml/100 g/min). Based on Xe-133 muscle washout method, we concluded that the muscle perfusion in the lower extremities of type II DM patients without symptoms/signs of PVD is significantly decreased and related to abnormal myocardial perfusion and more cardiovascular risk factors.

Usefulness of technetium-99m sestamibi myocardial perfusion SPECT in detection of cardiovascular involvement in patients with systemic lupus erythematosus or systemic sclerosis.

The main purpose of the study was to evaluate the utility of technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography (Tc-99m sestamibi SPECT) in detection of cardiac involvement in systemic lupus erythematosus (SLE) or systemic sclerosis (SS) patients. Fifty SLE or SS female patients with cardiac symptom/sign such as chest discomfort and/or dyspnea and/or occasionally palpitation and 50 SLE or SS female patients without any cardiac symptom/sign were investigated using Tc-99m sestamibi SPECT during rest and stress after dipyridamole infusion. Twenty-five age- and sex-matched healthy females were also included as controls in this study. The results of Tc-99m sestamibi SPECT were classified into four types including normal, persistent perfusion defect (PD), reversible perfusion defect (RD), and reverse perfusion defect (RR). The results of Tc-99m sestamibi SPECT in the 25 healthy females were normal. Perfusion abnormalities were detected in 44/50 (88%) symptomatic SLE or SS patients. However, myocardial perfusion abnormalities were only detected in 19/50 (38%) asymptomatic SLE or SS patients (P value<0.05 by a chi2 test). However, for risk factor of coronary artery disease and abnormal resting EKG, the incidences were not significant between symptomatic and asymptomatic patients (P values >0.05 by a chi2 test). Tc-99m sestamibi SPECT is a useful noninvasive imaging modality to detect cardiac involvement in symptomatic or asymptomatic SLE or SS patients.

Using technetium-99m methoxyisobutylisonitrile lung single-photon-emission computed tomography to predict response to chemotherapy and compare with P-glycoprotein expression in patients with untreated small cell lung cancer.

The purpose of this study was to predict chemotherapy response by technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) lung single-photon-emission computed tomography (SPECT) and compare P-glycoprotein (Pgp) expression in patients with untreated small cell lung cancer (SCLC). Before chemotherapy, 40 patients with untreated SCLC underwent Tc-99m MIBI lung SPECT. Immunohistochemical analyses were performed using multiple nonconsecutive sections of the biopsy specimens to detect Pgp expression. Chemotherapy response was evaluated in the third month after completion of treatment by clinical and radiological methods. Based on quantitative analyses, the tumor uptake ratios (TUR) of the 20 patients with good response (1.89 +/- 0.28) were significantly higher than that of the 20 patients with poor response (1.21 +/- 0.28) (p value < 0.05). Based on visual interpretation, all of the 20 patients (100%) with good response had positive Tc-99m TF lung SPECT findings and negative Pgp expression. Five of the other 20 patients (25%) with poor response had positive Tc-99m MIBI lung SPECT findings, and 12 of the other 20 patients (60%) with poor response had negative Pgp expression (p value < 0.05). Negative Tc-99m MIBI lung SPECT findings could predict poor response. Therefore, we concluded that Tc-99m MIBI lung SPECT can accurately predict the chemotherapy response, and Tc-99m MIBI lung SPECT findings can be partially compatible with Pgp expression in patients with untreated SCLC.

Uptake of 99mTc tetrofosmin in lymphoma cell lines: a comparative study with 99mTc sestamibi.

Technetium-99m (99mTc) tetrofosmin has been used as a tumor-seeking agent. However, its role in detecting lymphomas has not been widely investigated. The aim of the present study was to determine the uptake and clearance characteristics of 99mTc tetrofosmin in lymphoma cell lines. 99mTc sestamibi was also evaluated for comparison. Three lymphoma cell lines (U-937: monocyte-like, histiocytic lymphoma, human; RAMOS: B-lymphoma cell line, American Burkitt lymphoma, lymphoblastoid, human; Hs445: Hodgkin's disease, lymphoid, human) were studied. After incubation of radiotracers 99mTc tetrofosmin and 99mTc sestamibi in medium for 0, 10, 20, 30, 60, 120 and 180 min, the uptake and clearance of each radiotracer were measured in the three lymphoma cell lines. The uptake of 99mTc tetrofosmin was lower than that of 99mTc sestamibi in these lymphoma cell lines. Among the three cell lines, Hs445 showed the greatest 99mTc tetrofosmin uptake capacity. RAMOS and U-937 showed similar 99mTc tetrofosmin uptake capacities. 99mTc tetrofosmin accumulated in the three tested lymphoma cell lines, especially in the Hodgkin's disease cell line. However, in comparison with 99mTc sestamibi, 99mTc tetrofosmin may not be the best radiotracer for detection of lymphoma.

Comprehensive measurement for clinical dosimetry of tertiary multileaf collimator.

To initiate the use of a tertiary multileaf collimator (MLC) in the clinic, a set of dosimetry data for clinical use of the MLC, the secondary field size jaw and the MLC tracked by the jaw were measured. The dose calculation technique from the commissioned jaw field data was established. The dosimetry characteristics included absolute output (Dw), collimator scatter factor (Sc), total scatter factor (Scp), phantom scatter factor (Sp), percentage depth dose (PDD), tissue-maximum ratio (TMR), and peak scatter factor (PSF). The absolute output of the MLC field was +5% to +2% greater than that of the same jaw size field from 4 x 4 to 24 x 24 cm2 fields. The variation of Sc and Scp ranged from 4 x 4 to 24 x 24 cm2 fields and were less than that of the jaw fields, while the Sp, PDD and TMR values remained the same. Importantly, when the MLC-only field was performed without the collimator jaws tracking close to the field segments, greater output was delivered, and PSFs should be used to calculate the MLC field output.