Role of chest radiography in the diagnosis and follow-up of pulmonary metastasis in differentiated thyroid cancer.

BACKGROUND: Post-treatment I-131 whole body scan (WBS) is known to be a very sensitive test in detecting metastasis in differentiated thyroid cancer (DTC). Therefore, in the presence of this sensitive method, the role of chest radiography (CXR) in the diagnosis of pulmonary metastasis has been questioned. OBJECTIVE: The present study aimed to find the prevalence of pulmonary metastasis found on CXR in DTC patients who had negative post-treatment WBS. MATERIAL AND METHOD: Retrospective comparison was undertaken of CXR and post-treatment WBS routinely performed in 300 DTC patients during the time of I-131 treatment from January 2003 to December 2006 in the Department of Radiology. Radiographic patterns of pulmonary metastasis classified as single nodule, multiple nodules, lymphangitic metastasis and pleural metastasis were also recorded. RESULTS: Of the 300 DTC patients, 36 pulmonary metastases (12.0%) were diagnosed based on CXR and post-treatment I-131 WBS. Of these 36 cases, 11 (30.6%) were detected by both CXR and WBS, whereas 16 (44.4%) were detected by WBS alone and 9 (25.0%) by CXR alone. Seven of these 9 cases (77.8%) had lymphangitic pattern of pulmonary metastasis. CONCLUSION: Although routine CXR has a limited role in the diagnosis of pulmonary metastasis in DTC patients being treated with I-131, it is helpful in detecting pulmonary metastasis in patients with negative post-treatment WBS.

Red Marrow Absorbed Dose Calculation in Thyroid Cancer Patient Using a Simplified Excel Spreadsheet

Objectives: Absorbed dose to red marrow (Drm) can be calculated using blood dosimetry. However, this method is laborious and invasive. Therefore, image-based dosimetry is the method of choice. Nonetheless, the commercial software is expensive. The goal of this work was to develop a simplified excel spreadsheet for image-based radioiodine red marrow dosimetry. Methods: The serial whole-body images (acquired at 2nd, 6th, 24th, 48th, and 72th hours) of 29 patients from the routine pretherapeutic dosimetry protocol were retrospectively reanalyzed. The commercial OLINDA/EXM image-based dosimetry software was used to calculate the whole-body time-integrated activity coefficient (TIACWB) and Drm [in terms of absorbed dose coefficient (drm)]. For the simplified excel spreadsheet, the wholebody count was obtained from the vendor-supplied software. Then, the TIACWB was computed by a fitting time-activity curve using an Excel function. S factor was taken from other publications and scaled according to the patient-specific mass. A comparison of the TIACWB and drm from both methods was done using a non-inferiority test using a paired t-test or the Wilcoxon signed-rank test. Results: The TIACWB showed no significant difference between both methods (p=0.243). The calculated Drm from a simplified Excel spreadsheet was assumed to be statistically non-inferior to the commercial OLINDA/EXM image-based dosimetry software with the non-inferiority margin of 0.02 (p<0.05). Conclusion: The dose assessment from a simplified Excel spreadsheet is feasible and relatively low cost compared to the commercial OLINDA/EXM image-based dosimetry software.

Fixed defect on rest/stress Tc-99m sestamibi study underestimates myocardial ischemia: comparison with 24-hour thallium-201 study for short- and intermediate-term follow-up.

PURPOSE: We assessed whether a same day rest/stress gated Tc-99m sestamibi (MIBI) SPECT myocardial study underestimates reversible ischemia in patients with fixed perfusion defects compared with a 24-hour thallium-201 (Tl-201) study. The short- and intermediate-term outcome with or without Tl-201 reversibility was assessed. METHODS: Forty-nine consecutive patients with fixed MIBI defects received an additional Tl-201 study and were evaluated. Tl-201 was given to patients with a high clinical suspicion of underestimation of reversibility. Images were interpreted semiquantitatively by 3 nuclear medicine physicians using a 17-segment, 5-point model. A summed stress score (SSS) from stress MIBI images, a summed rest score (SRS) from Tl images, and a summed difference (SDS = SSS - SRS) score were calculated. SDS >3 indicated significant Tl-201 redistribution. Composite end points included acute myocardial infarction, unstable angina needing admission, cardiac death, or revascularization within 3 and 6 months. RESULTS: Fifteen of 49 patients showed no Tl-201 redistribution. Thirty-four of 49 (69%) patients had significant Tl-201 redistribution, and these patients had significantly higher cardiac events (CE) at 3 months (29% vs. 7%; P = 0.039), and higher at 6 months (32% vs. 7%; P = 0.027). These patients with CE had a larger amount of Tl-201 redistribution, mean SDS 8.6 vs. 5.3 (P = 0.047). Patients with significant Tl-201 redistribution had a lower left ventricular ejection fraction (mean 37%; P = 0.001). CONCLUSION: With short- and intermediate-term follow-up, our study shows a significant association towards fixed defects on the rest/stress MIBI study underestimating CE risk when compared with a delayed Tl-201 study, especially in patients with a large amount of Tl-201 redistribution. Hence, the addition of a Tl-201 study may be useful in the management of patients with large fixed MIBI defects, especially with a depressed left ventricular ejection fraction.

Quality Assessment of Research Articles in Nuclear Medicine Using STARD and QUADAS-2 Tools.

OBJECTIVES: Diagnostic nuclear medicine is being increasingly employed in clinical practice with the advent of new technologies and radiopharmaceuticals. The report of the prevalence of a certain disease is important for assessing the quality of that article. Therefore, this study was performed to evaluate the quality of published nuclear medicine articles and determine the frequency of reporting the prevalence of studied diseases. METHODS: We used Standards for Reporting of Diagnostic Accuracy (STARD) and Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) checklists for evaluating the quality of articles published in five nuclear medicine journals with the highest impact factors in 2012. The articles were retrieved from Scopus database and were selected and assessed independently by two nuclear medicine physicians. Decision concerning equivocal data was made by consensus between the reviewers. RESULTS: The average STARD score was approximately 17 points, and the highest score was 17.19±2.38 obtained by the European Journal of Nuclear Medicine. QUADAS-2 tool showed that all journals had low bias regarding study population. The Journal of Nuclear Medicine had the highest score in terms of index test, reference standard, and time interval. Lack of clarity regarding the index test, reference standard, and time interval was frequently observed in all journals including Clinical Nuclear Medicine, in which 64% of the studies were unclear regarding the index test. Journal of Nuclear Cardiology had the highest number of articles with appropriate reference standard (83.3%), though it had the lowest frequency of reporting disease prevalence (zero reports). All five journals had the same STARD score, while index test, reference standard, and time interval were very unclear according to QUADAS-2 tool. Unfortunately, data were too limited to determine which journal had the lowest risk of bias. In fact, it is the author's responsibility to provide details of research methodology so that the reader can assess the quality of research articles. CONCLUSION: Five nuclear medicine journals with the highest impact factor were comparable in terms of STARD score, although they all showed lack of clarity regarding index test, reference standard, and time interval, according to QUADAS-2. The current data were too limited to determine the journal with the lowest bias. Thus, a comprehensive overview of the research methodology of each article is of paramount importance to enable the reader to assess the quality of articles.

Normal Solid Gastric Emptying Values Measured by Scintigraphy Using Asian-style Meal:A Multicenter Study in Healthy Volunteers.

BACKGROUND/AIMS: To report gastric emptying scintigraphy, normal values should be established for a specific protocol. The aim of this study was to provide normal gastric emptying values and determine factors affecting gastric emptying using Asian rice-based meal in healthy volunteers. METHODS: One hundred and ninety-two healthy volunteers were included at 7 tertiary care centers across Thailand. Gastric emptying scintigraphy was acquired in 45 degree left anterior oblique view immediately after ingestion of a 267 kcal steamed-rice with technetium-99m labeled-microwaved egg meal with 100 mL water for up to 4 hours. RESULTS: One hundred and eighty-nine volunteers (99 females, age 43 ± 14 years) completed the study. The medians (5-95th percentiles) of lag time, gastric emptying half time (GE T1/2) and percent gastric retentions at 2 and 4 hours for all volunteers were 18.6 (0.5-39.1) minutes, 68.7 (45.1-107.8) minutes, 16.3% (2.7-49.8%) and 1.1% (0.2-8.8%), respectively. Female volunteers had significantly slower gastric emptying compared to male (GE T1/2, 74 [48-115] minutes vs. 63 (41-96) minutes; P < 0.05). Female volunteers who were in luteal phase of menstrual cycle had significantly slower gastric emptying compared to those in follicular phase or menopausal status (GE T1/2, 85 [66-102] mintes vs. 69 [50-120] minutes or 72 [47-109] minutes, P < 0.05). All of smoking volunteers were male. Smoker male volunteers had significantly faster gastric emptying compared to non-smoker males (GE T1/2, 56 [44-80] minutes vs. 67 [44-100] minutes, P < 0.05). Age, body mass index and alcohol consumption habits did not affect gastric emptying values. CONCLUSIONS: A steamed-rice with microwaved egg meal was well tolerated by healthy volunteers. Gender, menstrual status and smoking status were found to affect solid gastric emptying.