Diagnostic accuracy of dopaminergic imaging in prodromal dementia with Lewy bodies.

BACKGROUND: Dopaminergic imaging has high diagnostic accuracy for dementia with Lewy bodies (DLB) at the dementia stage. We report the first investigation of dopaminergic imaging at the prodromal stage. METHODS: We recruited 75 patients over 60 with mild cognitive impairment (MCI), 33 with probable MCI with Lewy body disease (MCI-LB), 15 with possible MCI-LB and 27 with MCI with Alzheimer's disease. All underwent detailed clinical, neurological and neuropsychological assessments and FP-CIT [123I-N-fluoropropyl-2ß-carbomethoxy-3ß-(4-iodophenyl)] dopaminergic imaging. FP-CIT scans were blindly rated by a consensus panel and classified as normal or abnormal. RESULTS: The sensitivity of visually rated FP-CIT imaging to detect combined possible or probable MCI-LB was 54.2% [95% confidence interval (CI) 39.2-68.6], with a specificity of 89.0% (95% CI 70.8-97.6) and a likelihood ratio for MCI-LB of 4.9, indicating that FP-CIT may be a clinically important test in MCI where any characteristic symptoms of Lewy body (LB) disease are present. The sensitivity in probable MCI-LB was 61.0% (95% CI 42.5-77.4) and in possible MCI-LB was 40.0% (95% CI 16.4-67.7). CONCLUSIONS: Dopaminergic imaging had high specificity at the pre-dementia stage and gave a clinically important increase in diagnostic confidence and so should be considered in all patients with MCI who have any of the diagnostic symptoms of DLB. As expected, the sensitivity was lower in MCI-LB than in established DLB, although over 50% still had an abnormal scan. Accurate diagnosis of LB disease is important to enable early optimal treatment for LB symptoms.

Opportunities for improvement on current nuclear cardiology practices and radiation exposure in Latin America: Findings from the 65-country IAEA Nuclear Cardiology Protocols cross-sectional Study (INCAPS).

BACKGROUND: Comparison of Latin American (LA) nuclear cardiology (NC) practice with that in the rest of the world (RoW) will identify areas for improvement and lead to educational activities to reduce radiation exposure from NC. METHODS AND RESULTS: INCAPS collected data on all SPECT and PET procedures performed during a single week in March-April 2013 in 36 laboratories in 10 LA countries (n = 1139), and 272 laboratories in 55 countries in RoW (n = 6772). Eight "best practices" were identified a priori and a radiation-related Quality Index (QI) was devised indicating the number used. Mean radiation effective dose (ED) in LA was higher than in RoW (11.8 vs 9.1 mSv, p < 0.001). Within a populous country like Brazil, a wide variation in laboratory mean ED was found, ranging from 8.4 to 17.8 mSv. Only 11% of LA laboratories achieved median ED <9 mSv, compared to 32% in RoW (p < 0.001). QIs ranged from 2 in a laboratory in Mexico to 7 in a laboratory in Cuba. Three major opportunities to reduce ED for LA patients were identified: (1) more laboratories could implement stress-only imaging, (2) camera-based methods of ED reduction, including prone imaging, could be more frequently used, and (3) injected activity of 99mTc could be adjusted reflecting patient weight/habitus. CONCLUSIONS: On average, radiation dose from NC is higher in LA compared to RoW, with median laboratory ED <9 mSv achieved only one third as frequently as in RoW. Opportunities to reduce radiation exposure in LA have been identified and guideline-based recommendations made to optimize protocols and adhere to the "as low as reasonably achievable" (ALARA) principle.

PREDICTION OF RELAPSE FROM HYPERTHYROIDISM FOLLOWING ANTITHYROID MEDICATION WITHDRAWAL USING TECHNETIUM THYROID UPTAKE SCANNING.

OBJECTIVE: Technetium thyroid uptake (TTU) is not inhibited by antithyroid drugs (ATD) and reflects the degree of thyroid stimulation. We intended to predict the relapse rate from hyperthyroidism based on TTU measurement. METHODS: Out of 44 initially enrolled subjects, 38 patients aged 41.6 ± 14.6 with Graves disease (duration: 84 ± 78 months) completed the study. TTU was performed with 40-second imaging of the neck and mediastinum 20 minutes after injection of 1 mCi technetium-99m pertechnetate. TTU was measured as the percentage of the count of activity accumulated in the thyroidal region minus the mediastinal background uptake to the count of 1 mCi technetium-99m under the same acquisition conditions. Then methimazole was stopped and patients were followed. The optimal TTU cutoff value for Graves relapse prediction was calculated using Youden's J statistic. RESULTS: Hyperthyroidism relapsed in 11 (28.9%) patients 122 ± 96 (range: 15-290) days post-ATD withdrawal. The subjects in remission were followed for 209 ± 81 days (range: 88-390). TTU was significantly higher in patients with forthcoming relapse (12.0 ± 8.0 vs. 3.9 ± 2.0, P = .007). The difference was significant after adjustment for age, sex, history of previous relapse, disease duration, and thyroid-stimulating hormone (TSH) levels before withdrawal. The area under the receiver operative characteristic (ROC) curve was 0.87. The optimal TTU cutoff value for classification of subjects with relapse and remission was 8.7 with sensitivity, specificity, and positive and negative predictive value of 73%, 100%, 100%, and 90%, respectively (odds ratio [OR] = 10.0; 95% confidence interval [CI]: 3.4-29.3). CONCLUSION: TTU evaluation in hyperthyroid patients receiving antithyroid medication is an accurate and practical method for predicting relapse after ATD withdrawal. ABBREVIATIONS: ATD = antithyroid drugs RIU = radio-iodine uptake TSH = thyroid-stimulating hormone TSI = thyroid-stimulating immunoglobulin TTU = technetium thyroid uptake.

Current status of nuclear cardiology in Japan: Ongoing efforts to improve clinical standards and to establish evidence.

Nuclear cardiology imaging tests are widely performed in Japan as clinical practice. The Japanese nuclear cardiology community has developed new diagnostic imaging tests using (123)I-beta-methyl-p-iodophenyl-pentadecanoic acid, (123)I-metaiodobenzylguanidine, and (18)F-fluorodeoxyglucose PET for detecting cardiac involvement in sarcoidosis. These tests have become popular worldwide. The Japanese Circulation Society and the Japanese Society of Nuclear Cardiology have published clinical imaging guidelines showing indications and standards for the new imaging tests. JSNC is currently striving to improve the standard of clinical practice and is promoting research activities.

Comparison of RECIST and Choi criteria for computed tomographic response evaluation in patients with advanced gastrointestinal stromal tumor treated with sunitinib.

BACKGROUND: Controversies exist about computed tomography (CT) response evaluation criteria for patients with gastrointestinal stromal tumor (GIST). PATIENTS AND METHODS: Fifty-one patients with advanced GIST treated second line with sunitinib were evaluated with contrast-enhanced CT every 3 months. Response was rated according to RECIST and Choi criteria. Progression-free survival (PFS) and overall survival (OS) were estimated by Kaplan-Meier analysis. RESULTS: According to RECIST, patients were categorized as complete response (CR; n = 0; 0%), partial remission (PR; n = 1; 2.0%), stable disease (SD; n = 37; 72.5%), and progressive disease (PD; n = 13; 25.5%) at 3 months. When Choi criteria were applied responses were CR (n = 0; 0%), PR (n = 16; 31.4%), SD (n = 21; 41.1%), and PD (n = 14; 27.5%). Despite these discrepancies, patients rated as SD with RECIST and PR as well as SD according to Choi criteria displayed similar PFS (41.3, 40.7, and 41.3 weeks, respectively) and OS (100.4, 91.6, and 108.0 weeks, respectively). Patients with PD had significantly shorter PFS (10.1 weeks for both criteria) and OS (29.1 weeks for RECIST; 28.9 weeks for Choi) regardless of the response classification applied. CONCLUSION: In contrast to absence of progression, discrimination of PR from SD with Choi criteria was of no predictive value.

Screening of Potential Cardiac Involvement in Competitive Athletes Recovering From COVID-19: An Expert Consensus Statement.

As our understanding of the complications of coronavirus disease-2019 (COVID-19) evolve, subclinical cardiac pathology such as myocarditis, pericarditis, and right ventricular dysfunction in the absence of significant clinical symptoms represents a concern. The potential implications of these findings in athletes are significant given the concern that exercise, during the acute phase of viral myocarditis, may exacerbate myocardial injury and precipitate malignant ventricular arrhythmias. Such concerns have led to the development and publication of expert consensus documents aimed at providing guidance for the evaluation of athletes after contracting COVID-19 in order to permit safe return to play. Cardiac imaging is at the center of these evaluations. This review seeks to evaluate the current evidence regarding COVID-19-associated cardiovascular disease and how multimodality imaging may be useful in the screening and clinical evaluation of athletes with suspected cardiovascular complications of infection. Guidance is provided with diagnostic "red flags" that raise the suspicion of pathology. Specific emphasis is placed on the unique challenges posed in distinguishing athletic cardiac remodeling from subclinical cardiac disease. The strengths and limitations of different imaging modalities are discussed and an approach to return to play decision making for athletes post-COVID-19, as informed by multimodality imaging, is provided.

Lung cancer screening--comparison of computed tomography and X-ray.

Recent studies on lung cancer screening with CT disclosed a discrepancy between its efficiency in detecting early lung cancer and a lack of proof for decreasing mortality from lung cancer. The present study, in a city in Japan where an X-ray screening program is provided, bi-annual CT screening was performed for X-ray screening negative subjects for 4 years. Ten patients with lung cancer were detected among 22,720 person-year subjects (0.044%) through the X-ray screening. Among the X-ray screening-negative subjects, 3305 subjects participated in a CT screening program resulting in the detection of 15 patients with lung cancer (0.454%). All 15 cases detected by CT screening and 5 of the 10 cases detected by X-ray screening were at stage IA. In respect of gender, histological type and CT findings, patients detected by CT screening had a better prognostic profile than those detected by X-ray screening. Survival was significantly better in the former than the latter, both in its entirety comparison and in a comparison limited to patients who underwent surgery. In conclusion, CT screening might have the potential to detect lung cancer with good prognostic factors not limited to early detection. Sufficiently long follow-up time, therefore, would be required to evaluate the efficacy for decreasing lung cancer mortality with CT screening.

Recommendations for optimal use of imaging studies to clinically stage mediastinal lymph nodes in non-small-cell lung cancer patients.

Appropriate clinical staging of mediastinal lymph nodes in non-small-cell lung cancer (NSCLC) patients has important therapeutic and prognostic implications. Because of the wide variations in practice patterns among community and academic physicians, we reviewed the literature so that we could provide evidence-based recommendations on the use of imaging studies in the pretreatment clinical staging of NSCLC patients. We concluded that the most sensitive and accurate method of noninvasive mediastinal nodal staging is a positron emission tomography/computed tomography fusion scan; we believe this tool should be a component of clinical staging of all NSCLC patients. Given insufficient sensitivity with currently available imaging studies, mediastinal nodal staging should also include histologic evaluation.

Infrequently performed studies in nuclear medicine: Part 1.

Nuclear medicine is a diverse field with a large number of different studies spanning virtually all organ systems and medical specialties. Many nuclear medicine procedures are performed routinely; others may be performed only rarely, sometimes less than once per year. The infrequent nature of many studies makes it challenging to retain relevant knowledge and skills. This 2-part article provides a review of several infrequently performed studies. The topics discussed in Part 1 include dacroscintigraphy, LeVeen shunts, scintimammography, right-to-left shunts, left-to-right shunts, and heat-damaged red blood cells. After reading this article, the reader should be able to list and describe the indications for each study, list the doses and describe their proper method of administration, and describe problems that may arise during the imaging procedure and how they should be handled.

An individualized strategy to estimate the effect of deformable registration uncertainty on accumulated dose in the upper abdomen.

In the abdomen, it is challenging to assess the accuracy of deformable image registration (DIR) for individual patients, due to the lack of clear anatomical landmarks, which can hamper clinical applications that require high accuracy DIR, such as adaptive radiotherapy. In this study, we propose and evaluate a methodology for estimating the impact of uncertainties in DIR on calculated accumulated dose in the upper abdomen, in order to aid decision making in adaptive treatment approaches. Sixteen liver metastasis patients treated with SBRT were evaluated. Each patient had one planning and three daily treatment CT-scans. Each daily CT scan was deformably registered 132 times to the planning CT-scan, using a wide range of parameter settings for the registration algorithm. A subset of 'realistic' registrations was then objectively selected based on distances between mapped and target contours. The underlying 3D transformations of these registrations were used to assess the corresponding uncertainties in voxel positions, and delivered dose, with a focus on accumulated maximum doses in the hollow OARs, i.e. esophagus, stomach, and duodenum. The number of realistic registrations varied from 5 to 109, depending on the patient, emphasizing the need for individualized registration parameters. Considering for all patients the realistic registrations, the 99th percentile of the voxel position uncertainties was 5.6 ± 3.3 mm. This translated into a variation (difference between 1st and 99th percentile) in accumulated D max in hollow OARs of up to 3.3 Gy. For one patient a violation of the accumulated stomach dose outside the uncertainty band was detected. The observed variation in accumulated doses in the OARs related to registration uncertainty, emphasizes the need to investigate the impact of this uncertainty for any DIR algorithm prior to clinical use for dose accumulation. The proposed method for assessing on an individual patient basis the impact of uncertainties in DIR on accumulated dose is in principle applicable for all DIR algorithms allowing variation in registration parameters.

A priori selection of the regularization parameters in emission tomography by Fourier synthesis.

This paper describes how the stability of the inverse problem underlying emission tomography can be measured and controlled in clinical settings. We show how the Lanczos approximation provides a way to regularize a certain class of iterative reconstruction algorithms through a given level of noise or resolution in the slices and for a given acquisition protocol. Moreover, we show how the same Lanczos approximation can be used to decide when the iterative reconstruction algorithm actually converges for a given machine precision. These ideas are illustrated by means of reconstructions of simulated and actual emission datasets.

Implications of full compliance with the computed tomography scanning recommendations of the National Institute for Clinical Excellence and Scottish Intercollegiate Guidelines Network guidelines for the management of head injury.

A prospective study was conducted to examine clinical practices in the management of head-injured patients preinception and postinception of the Scottish Intercollegiate Guidelines Network guidelines. Comparison was made between the Scottish Intercollegiate Guidelines Network and National Institute for Clinical Excellence guidelines on their indications for computed tomography scanning. Information was available on 2827 adult patients. Two hundred and thirty-two patients satisfied one or more Scottish Intercollegiate Guidelines Network criteria for computed tomography scanning. Four hundred and seventy-eight patients fulfilled one or more National Institute for Clinical Excellence criteria for scanning. No patient with Scottish Intercollegiate Guidelines Network or National Institute for Clinical Excellence indications for computed tomography scanning and who was not scanned, subsequently required neurosurgical treatment for a complication related to their injury. Full compliance with the scanning recommendations in the Scottish Intercollegiate Guidelines Network and National Institute for Clinical Excellence guidelines will require a significant increase in scanning resource and is unlikely to lead to the identification of a significant additional number of patients with intracranial lesions requiring neurosurgical intervention.

Incidental gallbladder visualization on nonhepatobiliary nuclear medicine studies: case series and review of the literature.

Gallbladder uptake is occasionally encountered with commonly used nonhepatobiliary radiopharmaceuticals. Identification of the biliary tract by a nonhepatobiliary agent can identify disease, such as uptake of labeled white blood cells. However, in most cases, gallbladder uptake of nonhepatobiliary tracers is not due to pathology in these cases. It is important to avoid attributing gallbladder uptake to disease in the gallbladder or adjacent anatomic structures. We present 3 cases of unexpected gallbladder tracer uptake and provide a review of the literature describing incidental gallbladder uptake on nonhepatobiliary nuclear medicine studies. The potential for misdiagnosis and the steps taken to avoid this are discussed.

Impact of the Publication of Appropriate Use Criteria on Utilization Rates of Myocardial Perfusion Imaging Studies in Ontario, Canada: A Population-Based Study.

BACKGROUND: Concern regarding overutilization of cardiac imaging has led to the development of appropriate use criteria (AUC). Myocardial perfusion imaging (MPI) is one of the most commonly used cardiac imaging modalities worldwide. Despite multiple iterations of AUC, there is currently no evidence regarding their real-world impact on population-based utilization rates of MPI. Our goal was to assess the impact of the AUC on rates of MPI in Ontario, Canada. We hypothesized that publication of the AUC would be associated with a significant reduction in MPI rates. METHODS AND RESULTS: We conducted a retrospective cohort study of the adult population of Ontario from January 1, 2000, to December 31, 2015. Age- and sex-standardized rates were compared from 4 different periods intersected by 3 published iterations of the AUC. Overall, 3 072 611 MPI scans were performed in Ontario during our study period. The mean monthly rate increased from 14.1/10 000 in the period from January 2000 to October 2005 to 18.2/10 000 between November 2005 and June 2009. After this point in time, there was a reduction in rates, falling to a mean monthly rate of 17.1/10 000 between March 2014 and December 2015. Time series analysis revealed that publication of the 2009 AUC was associated with a significant reduction in MPI rates (P<0.001). This translated into ≈88 849 fewer MPI scans at a cost savings of ≈72 million Canadian dollars. CONCLUSIONS: Our results reflect a potential real-world impact of the 2009 MPI AUC by demonstrating evidence of a significant effect on population-based rates of MPI.