Using Cine-Averaged CT With the Shallow Breathing Pattern to Reduce Respiration-Induced Artifacts for Thoracic Cavity PET/CT Scans.

OBJECTIVE. PET/CT provides a fusion of both anatomic and functional information. However, because of the temporal difference of both modalities and respiratory motion of lungs, misregistration of lesions is frequently observed on thoracic PET/CT scans. The effect of cine-averaged CT (CACT) acquisition incorporated with the shallow breathing pattern of patients on the improvement of registration and quantification of lesions was investigated. MATERIALS AND METHODS. Thirty patients with cancer who underwent routine PET/CT followed by CACT of the thoracic region were enrolled. The misalignment between PET/helical CT (HCT) and PET/CACT was calculated. In addition, the PET data were attenuation-corrected by HCT and CACT images, and the maximum standardized uptake value (SUVmax) was evaluated. RESULTS. All lesions in the PET/HCT images showed misalignment larger than 5 mm, whereas only 33% of lesions in the PET/CACT images showed misalignment larger than 5 mm. The mean values of the maximum misalignment of the lesions in PET/HCT and PET/CACT images were 14.10 ± 6.26 mm and 5.92 ± 4.31 mm, respectively. Seven percent of the lesions had an increase in SUVmax of more than 20%, and 47% showed a slight increase in SUVmax of less than 5% after applying CACT. The mean percentage difference between the SUVmax of CACT and that of HCT was 12%. CONCLUSION. Using the CACT technique and the shallow breathing pattern effectively reduces misregistration of lesions and recovers the underestimated SUVmax. The CACT method can be applied in clinical practice of thoracic PET/CT for better cancer management.

Colon Visualization on Bone Scan Due to Recto-abscess Fistula From Urinoma.

The accumulation of the bone-seeking agent in the bowel during a bone scan is rare. A 68-year-old man with colon cancer underwent bone scintigraphy for staging. Whole-body images revealed an abnormal accumulation of hot radioactivity in the abdominal cavity and the colon. Abdominal CT showed a recto-abscess fistula between the rectum and the urinoma. Incidental visualization of colonic radioactivity suggested the presence of a fistula between the bowel and the urinoma, explaining the peculiar finding of the bone-seeking agent in the bowel.

Consensus of official position of IOF/ISCD FRAX initiatives in Asia-Pacific region.

The fracture risk assessment tool (FRAX(®)) has been developed for the identification of individuals with high risk of fracture in whom treatment to prevent fractures would be appropriate. FRAX models are not yet available for all countries or ethnicities, but surrogate models can be used within regions with similar fracture risk. The International Society for Clinical Densitometry (ISCD) and International Osteoporosis Foundation (IOF) are nonprofit multidisciplinary international professional organizations. Their visions are to advance the awareness, education, prevention, and treatment of osteoporosis. In November 2010, the IOF/ISCD FRAX initiative was held in Bucharest, bringing together international experts to review and create evidence-based official positions guiding clinicians for the practical use of FRAX. A consensus meeting of the Asia-Pacific (AP) Panel of the ISCD recently reviewed the most current Official Positions of the Joint Official Positions of ISCD and IOF on FRAX in view of the different population characteristics and health standards in the AP regions. The reviewed position statements included not only the key spectrum of positions but also unique concerns in AP regions.

Analysis of factors associated with volumetric data errors in gamma knife radiosurgery.

OBJECT: Gamma knife (GK) surgery is an important part of the treatment armamentarium for benign and malignant brain tumors. In general, quantitative volumetrical analysis of the tumor on neuroimaging studies is the most reliable method of assessment of the tumor's response and is critical for accurate dose planning. This study evaluated various factors contributing to volumetric data error of tumors treated with GK radiosurgery. METHOD: Three differently shaped phantoms (spherical, rectangular, and irregular morphology) were created by immersing like shaped objects into 2% agarose gel. The volumes of phantoms were measured by laser scanning with errors <1%. MRI sequence and parameters including time of flight (TOF), T(1), T(2), different slice thickness, size of field of view (FOV), phase FOV as well as different position and axis of phantoms were retrieved and transferred to a Perfexion Gamma Knife Workstation (PGK-WS) and Picture Archiving and Communication System (PACS) for data analysis. The volumetric data errors were presented as the volume difference between those computed on the PGK-WS and actual volume measured by laser scanning divided by the actual laser scanning volume. The systemic error was defined as volume discrepancy between Perfexion and PACS over that in Perfexion. One-way ANOVA was used for evaluation of data errors between different methods as well as for factor analysis. RESULTS: The MRI-computed volume of the various phantoms approached the laser-scanned volume within 2% when the slice number was >or=30. The volumetrical data errors (10/5 slices) associated with various MRIs for phantoms were 6.94 +/- 0.04%/9.45 +/- 0.35% (spherical phantom), 12.3 +/- 0.2%/ 20.06 +/- 0.7% (rectangular phantom), and 9.29 +/- 0.078%/ 15.67 +/- 0.6% (irregular phantom) (p < 0.001 and p < 0.001), respectively. The system errors (10/5 slices) associated with various MRIs for the phantoms were 3.17 +/- 0.11%/3.9 +/- 0.13% (spherical phantom), 3.61 +/- 0.12%/4.01 +/- 0.12% (rectangular phantom), and 4.39 +/- 0.07%/4.75 +/- 0.13% (irregular phantom) (p < 0.001 and p = 0.01), respectively. The volumetric data errors were related to the number of slices and the shape of phantom, but the systemic errors were only related to the irregularity of phantom morphology. The volumetrical data errors were not related to size of the FOV, phase FOV, sequence of T(1), T(2), TOF, and position of phantom. For the rectangular phantom, the data error was related to slice orientation of imaging acquisition (p < 0.001). CONCLUSION: Volume discrepancies existed between those volumes computed by the PGK-WS and volumes determined by laser scanning. The volumetric data errors were reduced through the acquisition of more slices through the phantom and a more spherical morphology of the phantom. Relatively few system volume errors were observed between those by the PGK-WS and PACS except for a significant discrepancy for the irregular surface phantom. For the rectangular-shaped phantom, the volumetric data errors were significantly related to slice orientation of measurement. When measuring the tumor response in GK radiosurgery or follow-up, an error of as large as 20% is possible for irregularly shaped object and with MRIs using

Biodistribution and dosimetry of (131)I in thyroidectomy patients using semiquantitative gamma-camera imaging.

The aim of this study was to determine the biodistribution, effective retention half-time (T(eff)), and internal organ dosimetry of (131)I administered to patients with papillary thyroid cancer after a total or near total thyroidectomy, and whole-body and organ activity was measured by gamma-camera imaging at 16 time points over 5 days following the administration of 1.1 GBq of (131)I in 5 patients. Whole-body scanning was performed by using a Siemens E-CAM() gamma-camera at a fixed distance of 5 cm from the patient. (131)I activity in regions of interest (ROIs) corresponding to the bladder, heart wall, kidneys, liver, lower gastrointestinal tract, lung, stomach, and thyroid remnants were measured, with measurements in the thigh used as the background. Most activity was localized to the lower gastrointestinal tract and thyroid remnants on day 1. The longest T(eff) was in the lung and the shortest was in the bladder (34.0 and 16.8 hours, respectively). The three organs with the highest absorbed doses per unit of administered activity were the lower gastrointestinal tract (2.03 mSv/MBq), the stomach (1.32 mSv/MBq), and the heart wall (1.24 mSv/MBq). T(eff) for thyroid remnants and the whole body were also estimated. We evaluated these organ doses to determine the normal tissues most likely at risk for stochastic and deterministic effects associated with (131)I therapy for thyroid cancer and benign disease. Our results represent preliminary findings, and the study will continue to accrue a greater number of study participants.

Effective half life of iodine for five thyroidectomy patients using an in vivo gamma camera approach.

The effective half-life of radioactive iodine for (near) thyroidectomy patients was evaluated using an in vivo gamma camera approach. Five patients with post administered iodine for remnant ablation of thyroid were thoroughly scanned in vivo for one to four weeks. Derived data were analyzed in a MATLAB program to revise the ICRP recommended effective half-life and, thus, to offer a more reliable dose predication protocol from a health physics viewpoint. A quantitative index, AT (Agreement), was also introduced to specify the deviation between the actual measurement and the results fitted in MATLAB for each patient. The ATs were evaluated as 1.52 +/- 1.54 and 14.05 +/- 11.01 for the thyroid compartment and the remainder, re-spectively, indicating a slight discrepancy between the computed and practical results for the remainder. The actual effective half-life of iodine in the thyroid or the body fluid compartment shifted from 7.3d or 0.24 d to only 0.61 +/- 0.50 d or 0.49 +/- 0.23 d, respectively. Additionally, the integrated T(eff) for the remainder (both body fluid and whole body compartments) was still about 5.8d, since the body fluid and the whole body compartment was inseparable in real whole body scanning. The branching ratio from body fluid compartment to the thyroid and the excretion compartment also changed from 30% and 70% to 11.6 +/- 14.0% and 88.4 +/- 14.6%, respectively. The thyroid was the dominant compartment for a healthy person in the traditional biokinetic model. However, this dominant compartment was shifted to both thyroid and body fluid, based on analyses of the data following thyroidectomy, for the patients herein.

Limited value of 18F-2-deoxyglucose positron emission tomography to detect hepatocellular carcinoma in hepatitis B virus carriers.

BACKGROUND/AIMS: The differentiation of hepatocellular carcinoma from benign liver diseases in hepatitis B virus carriers by imaging studies based upon morphological aspects can be difficult. METHODOLOGY: FDG-PET (18F-2-deoxyglucose positron emission tomographies) were performed in 48 hepatitis B virus carriers to detect hepatocellular carcinoma and differentiate other benign liver diseases. In each patient, the focal liver lesion was visible by ultrasound and an elevated serum alpha-fetoprotein level was noted. Definite diagnosis was established after ultrasound-guided liver biopsy followed by histopathological examination. RESULTS: The histopathological examination revealed hepatocellular carcinoma in 36 patients and benign liver diseases in the remaining 12 patients. Twenty of 36 hepatocellular carcinomas were detectable by FDG-PET and none of 12 benign liver diseases were visualized by FDG-PET. The detection sensitivity of FDG-PET was not related to the echogenicity and size of hepatocellular carcinoma. CONCLUSIONS: FDG-PET is not sensitive to but is more specific than ultrasound and serum alpha-feto-protein level to detect hepatocellular carcinoma and differentiate from other benign liver diseases in hepatitis B virus carriers.

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.

F18-fluorodeoxyglucose positron emission tomography in detecting metastatic papillary thyroid carcinoma with elevated human serum thyroglobulin levels but negative I-131 whole body scan.

UNLABELLED: Papillary carcinomas are the most common thyroid malignancies. They invade the regional lymphatics and metastasize frequently to local lymph nodes in the neck. Distant metastasis, generally to the lungs, is also common. METHODS: The aim of this study is to evaluate the effectiveness of F18-fluorodeoxyglucose (FDG) positron emission tomography (PET) to detect metastatic lesions in patients with papillary thyroid carcinomas (PTC) after nearly total thyroidectomy and I-131 treatments who present with elevated human serum thyroglobulin (hTg) levels but negative 1-131 whole body scan (WBS). Twenty patients with PTC who underwent nearly total thyroidectomy and radioiodine treatments were included in this study. RESULTS: All of the 20 patients had negative I-131 WBS results and elevated hTg levels (hTg > or = 2.0 microIU/mL) under thyroid-stimulating hormone (TSH) stimulation (TSH > or = 30 microIU/mL). CONCLUSIONS: FDG-PET was perform to detect metastatic lesions. F18-fluorodeoxyglucose-PET could detect hypermetabolic lesions in 17 patients but failed to demonstrate miliary pulmonary metastases in two patients. No definite lesion was found in FDG-PET, x-ray chest computed tomography (CT) and other imaging studies of the remaining one patient This study showed that FDG-PET is a useful tool in detecting metastatic lesions in PTC with elevated hTg but negative I-131 WBS. However, miliary lung metastases may be missed in FDG-PET. In this circumstance, chest CT should be included in the follow-up protocol.

Detecting metastatic pelvic lymph nodes by 18F-2-deoxyglucose positron emission tomography in patients with prostate-specific antigen relapse after treatment for localized prostate cancer.

AIM: To evaluate whether positron emission tomography (PET) with (18)F-2-deoxyglucose (FDG) can detect pelvic lymph node metastases in prostate cancer patients who had elevated serum prostate-specific antigen (PSA) levels after treatment. METHODS: Twenty-four patients with a rising serum PSA level after treatment for localized prostate cancer were examined with FDG-PET before pelvic lymph node dissection. All patients had negative findings on whole body bone scan and equivocal pelvic computed tomography (CT) results. The results of FDG-PET were then compared to the histology of the pelvic lymph nodes obtained at surgery. RESULTS: Lymph node metastases were detected by histopathological examination in 16/24 (66.7%) patients. At the sites with histopathologically proven metastases, increased FDG uptake was found in 12/16 (75.0%) patients. In addition, there were 4 patients with false-negative results, but no patient with a false-positive result on FDG-PET images. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG-PET in detecting metastatic pelvic lymph nodes were 75.0, 100.0, 83.3, 100.0, and 67.7%, respectively. CONCLUSIONS: These results suggest that FDG-PET may be a valuable diagnostic tool in the staging of pelvic lymph nodes in patients with PSA relapse after treatment of localized prostate cancer when the whole body bone scan is negative and pelvic CT findings are equivocal.