Development of 99mTc-SDP-choline SPECT radiopharmaceutical for imaging of cerebrovascular diseases

Cerebrovascular diseases are known as serious public health problem worldwide, which can be addressed more precisely through molecular imaging of non-functional brain cells. CDP-choline is an active cerebrovascular chemotherapeutic agent that can be used for diagnosis of cerebrovascular diseases post radiolabeling with γ-emitter radioisotopes. In this study we developed ^99mTc labeled CDP-choline for imaging of cerebrovascular diseases particularly alzheimer, stroke, and parkinson's diseases. The radiosynthesis reaction resulted 97.47±2.34% radiochemical with promising stability, that is, >95% up to 6 h in blood serum. The biodistribution study in healthy mice revealed non-accumulated uptake of radiochemical in key body organs; in brain it was 8.59±1.11% ID/g at 1h post-injection which washed-out leaving behind 0.87±0.61% ID/g at 24 h post-injection. The over-all data revealed the ^99mTc-CDP-choline could be a good candidate for further imaging investigations in diseased animal model.

Trends in High- and Low-Value Cardiovascular Diagnostic Testing in Fee-for-Service Medicare, 2000-2016

IMPORTANCE

Owing to a rapid increase in rates of diagnostic cardiovascular testing in the 1990s and early 2000s, the Centers for Medicare & Medicaid Services implemented a series of payment changes intended to reduce overall spending on fee-for-service testing. Whether guideline-concordant testing has been subsequently affected is unknown to date.

OBJECTIVE

To determine whether changes in overall rates of use of diagnostic cardiovascular tests were associated with changes in high-value testing recommended by guidelines and low-value testing that is expected to provide minimal benefits.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study assessed a national 5% random sample of Medicare fee-for-service beneficiaries aged 65 to 95 years from January 1, 1999, through December 31, 2016. Data were analyzed from February 15, 2018, through August 15, 2019.

EXPOSURES

Eligibility to receive high-value testing (assessment of left ventricular systolic function among patients hospitalized with acute myocardial infarction or heart failure) and low-value testing (stress testing before low-risk noncardiac surgery and routine stress testing within 2 years of coronary revascularization not associated with acute care visits).

MAIN OUTCOMES AND MEASURES

Age- and sex-adjusted annual rates of overall, high-value, and low-value diagnostic cardiovascular testing.

RESULTS

Mean (SD) age was similar over time (75.57 [7.32] years in 2000-2003; 74.82 [7.79] years in 2012-2016); the proportion of women slightly declined over time (63.23% in 2000 to 2003; 57.27% in 2012 to 2016). The rate of overall diagnostic cardiovascular testing per 1000 patient-years among the 5% sample of Medicare beneficiaries increased from 275 in 2000 to 359 in 2008 (P < .001) and then declined to 316 in 2016 (P < .001). High-value testing increased steadily over the entire study period for patients with acute myocardial infarction (85.7% to 89.5%; P < .001) and heart failure (72.6% to 80.1%; P < .001). Low-value testing among patients undergoing low-risk surgery increased from 2.4% in 2000 to 3.8% in 2008 (P < .001) but then declined to 2.5% in 2016 (P < .001). Low-value testing within 2 years of coronary revascularization slightly increased from 47.4% in 2000 to 49.2% in 2003 (P = .03) but then declined to 30.8% in 2014 (P < .001).

CONCLUSIONS AND RELEVANCE

Rates of overall and low-value diagnostic cardiovascular testing appear to have declined considerably and rates of high-value testing have increased slightly. Payment changes intended to reduce spending on overall testing may not have adversely affected testing recommended by guidelines.

A quick glance at selected topics in this issue

"A quick glance at selected topics in this issue" aims to highlight contents of the Journal and provide a quick review to the readers.

Clinical, electrophysiological, and imaging study in essential tremor-Parkinson's disease syndrome

INTRODUCTION

Essential tremor-Parkinson's disease (ET-PD) syndrome is a clinical condition in which individuals with a long-lasting history of Essential tremor (ET) eventually develop Parkinson's disease (PD). The aim of the study was to investigate the accuracy performances of clinical, neurophysiological, and imaging biomarkers in differentiating patients affected by ET-PD syndrome from patients with ET or PD.

METHODS

Nineteen patients affected by ET-PD syndrome, 48 ET patients, and 37 tremor-dominant PD (t-PD) patients were included. Electrophysiological studies, including blink-reflex recovery cycle and tremor parameters analyses, were performed in all groups. Nigro-striatal and cardiac sympathetic denervation were also investigated. Sensitivity, specificity and accuracy of clinical, electrophysiological, and radiological features in differentiating ET-PD syndrome from ET and PD were calculated.

RESULTS

ET-PD patients had significantly lower rigidity (p = 0.007) and higher postural/kinetic tremor (p = 0.007) scores, in comparison to t-PD patients. ET-PD patients, differently from PD patients, had a synchronous pattern of resting tremor and, differently from ET patients, had abnormal blink-reflex recovery cycle. ET-PD patients also showed reduced nigro-striatal and cardiac sympathetic uptakes, albeit to a lesser extent than in PD patients. The highest accuracy values were found for the synchronous pattern of resting tremor (97.1%) in distinguishing ET-PD from PD, and for presence of abnormal blink-recovery cycle (100%) in distinguishing ET-PD syndrome from ET.

CONCLUSION

Our study demonstrates that some electrophysiological parameters, such as a synchronous resting tremor pattern and the abnormal blink-recovery cycle were the most accurate biomarkers in distinguishing patient with ET-PD syndrome from those with ET or those with PD.

Predicting progression of amnesic MCI: The integration of episodic memory impairment with perfusion SPECT

The present study aimed at assessing if the ability to predict progression from amnesic Mild Cognitive Impairment (aMCI) to dementia is improved by considering the presence at the baseline of Single Photon Emission Computed Tomography (SPECT) perfusion abnormalities in addition to a defect of long term memory. The Episodic Memory Score (EMS), a global index which integrates results obtained in subtests of the Rey's Verbal Learning Test and the Rey-Osterrieth Figure recall, were taken into account to evaluate defects of long term memory. The study sample consisted of 42 subjects affected by aMCI, who were followed-up during a two-year period. At the final follow-up 15 subjects progressed to AD. The EMS predicted progression from aMCI to dementia with a high level of sensitivity and a lower level of specificity, but the association of neuropsychological (EMS) and SPECT data (hypoperfusion in the Posterior Cingulate Cortex) increased the accuracy in predicting conversion from aMCI to AD. The association of results obtained by aMCI patients on memory tests and perfusion SPECT may improve the accuracy in detecting subjects who will progress to dementia. The use of currently available and low-cost investigations could be advantageous in terms of public health policies.

Imaging studies of the HIV-infected brain

Human immunodeficiency virus (HIV) enters the brain early after infecting humans and may remain in the central nervous system despite successful antiretroviral treatment. Many neuroimaging techniques were used to study HIV+ patients with or without opportunistic infections. These techniques assessed abnormalities in brain structures (using computed tomography, structural magnetic resonance imaging (MRI), diffusion MRI) and function (using functional MRI at rest or during a task, and perfusion MRI with or without a contrast agent). In addition, single-photon emission computed tomography with various tracers (e.g., thallium-201, Tc99-HMPAO) and positron emission tomography with various agents (e.g., [18F]-dexoyglucose, [11C]-PiB, and [11C]-TSPO tracers), were applied to study opportunistic infections or HIV-associated neurocognitive disorders. Neuroimaging provides diagnoses and biomarkers to quantitate the severity of brain injury or to monitor treatment effects, and may yield insights into the pathophysiology of HIV infection. As the majority of antiretroviral-stable HIV+ patients are living longer, age-related comorbid disorders (e.g., additional neuroinflammation, cerebrovascular disorders, or other dementias) will need to be considered. Other highly prevalent conditions, such as substance use disorders, psychiatric illnesses, and the long-term effects of combined antiretroviral therapy, all may lead to additional brain injury. Neuroimaging studies could provide knowledge regarding how these comorbid conditions impact the HIV-infected brain. Lastly, specific molecular imaging agents may be needed to assess the central nervous system viral reservoir.

Nuclear cardiology in China: 2017

This paper provides the current state of nuclear cardiology in China and contrasts it with the state of nuclear cardiology in the United States (US). The West China Hospital and New York-Presbyterian Hospital (NYPH) were used as representative hospitals to contrast nuclear cardiology in China and the US, respectively. In 2015, there were 101 medical cyclotrons, 774 SPECT or SPECT/CT, 240 PET/CT, and 6 PET/MR cameras in China. Most (~90%) of the nuclear cardiology studies are gated SPECT myocardial perfusion imaging (MPI), and ~10% are other types of studies including MUGA, PET/CT MPI, and viability studies. There are differences in nuclear cardiology between the West China Hospital and NYPH and these include those in cardiac stress tests, SPECT/CT acquisition protocols, PET/CT blood flow and viability studies, reimbursement, and fellowship training. In this paper, we aim to present status of nuclear cardiology in China and provide potential solutions.

Multimodality Imaging in Tumor Angiogenesis: Present Status and Perspectives

Angiogenesis is a complex biological process that plays a central role in progression of tumor growth and metastasis. It led to a search for antiangiogenic molecules, and to design antiangiogenic strategies for cancer treatment. Noninvasive molecular imaging, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT), could be useful for lesion detection, to select patients likely to respond to antiangiogenic therapies, to confirm successful targeting, and dose optimization. Additionally, nuclear imaging techniques could also aid in the development of new angiogenesis-targeted drugs and their validation. Angiogenesis imaging can be categorized as targeted at three major cell types: (I) non-endothelial cell targets, (II) endothelial cell targets, and (III) extracellular matrix proteins and matrix proteases. Even if radiopharmaceuticals studying the metabolism and hypoxia can be also used for the study of angiogenesis, many of the agents used in nuclear imaging for this purpose are yet to be investigated. The purpose of this review is to describe the role of molecular imaging in tumor angiogenesis, highlighting the advances in this field.

A quick glance at selected topics in this issue

A quick glance at selected topics in this issue" aims to highlight selected articles and provide a quick review to the readers.

Failed epilepsy surgery: is this the end?

Resective epilepsy surgery can lead to sustained seizure control in 70-80% of patients evaluated for epilepsy surgery, indicating that up to 30% of patients still have recurrent seizures after surgery. Definitions of failed epilepsy surgery vary amongst studies. This review focuses on seizure outcome predictors after reoperation, possible mechanisms of failure and best management for this difficult patient population.

A quick glance at selected topics in this issue

"A quick glance at selected topics in this issue" aims to highlight contents of the journal and provide a quick review to the readers.

Successful innovation: A time for change?

Innovation plays an important role in the advancement of nuclear cardiology, meeting the need for reduced exposure to radiation, and maintaining and improving image quality. As we innovate, it is important to understand the impact of these improvements on the clinical and research knowledge base that has made nuclear cardiology such a powerful clinical tool. The need for comparative studies insuring stability in the clinical applicability of our current guidelines and use of the prognostic power of radionuclide myocardial perfusion imaging in clinical practice is essential for new and innovative techniques. The existing data demonstrating the significant differences that can occur with the innovative techniques is explored. The need for tools to insure comparable data is available as we begin to utilize registries to inform our clinical practice and research will be an important part of the future of nuclear cardiology.

A quick glance at selected topics in this issue

A quick glance at selected topics in this issue aims to highlight selected articles and provide a quick review to the reader.

[New trends and novel possibilities in the radiodiagnosis of lung cancer]

In recent years there have been significant changes in the management of lung cancer. In 2009 a new staging system became effective while in 2011 a new adenocarcinoma classification was introduced. Molecular biology, genetics with hybrid multimodal imaging progressed greatly. New biopsy needles were developed for the histological analysis in molecular pathology. Role of LDCT screening in early diagnosis of lung cancer became evident and working groups put it into practice. Integrated and multiparametric devices facilitate more accurate patient follow-up with new biomarkers and newly developed contrast materials. The future of radiology is in the combined use of anatomical, functional and molecular medical imaging.

[New trends and novel possibilities in functional medical imaging: imaging methods]

The aim of the study is to review the new tomographic imaging technologies which enable to investigate the metabolic activity of the human body. Accordingly, we overview the current promising methodology in the field of PET and SPECT, but we will also mention interesting applications at the area of MRI and CT.

[New trends and novel possibilities in the clinical use of SPECT/CT imaging]

The application of hybrid equipments and fused techniques has increasing importance in the field of imaging diagnostics. The biggest advantage of these methods is the simultaneous use of several modalities which can give data about the morphological, functional as well as molecular changes of the different diseases at the same time. The facilities, advantages and the applicability of the SPECT/CT (single photon emission computer tomograph/computer tomograph) are summarized in this paper mainly in oncologic diseases, but also in other disorders. The multimodality equipments showing the function and morphology together increase the specificity and diagnostic accuracy of the nuclear medicine methods and were found to be more efficient in the therapy effectiveness, too.

Scintimammography for the detection of breast cancer

Scintimammography is a functional imaging technique whereby radionuclide tracers in the patient's breasts are observed with a radiation-detection camera (gamma-camera). Tracers are designed to accumulate in tumors more than in healthy tissue; the most common tracers used to date are Tc-99m sestamibi and Tc-99m tetrofosmin. Scintimammography is useful in some clinical indications as an adjunct to mammography and to reduce the rates of negative biopsies, and it is recommended for lesions where additional information is required to reach a definitive diagnosis. Patients with equivocal mammograms may benefit from this test, as well as women with dense breasts and those with implants, since scintigraphy is not affected by breast density and the photons arising from the radiotracer are not overly attenuated by implants. Scintimammography is also of value in patients with locally advanced breast cancer, for monitoring and predicting the response to neoadjuvant chemotherapy. The near availability of high-resolution breast-dedicated cameras will allow the suboptimal sensitivity in detecting cancers of less than 1 cm to be improved; this is currently the main limitation of scintimammography. These new devices also have the potential to increase the number of breast scintigraphies performed and the role of nuclear medicine in breast cancer imaging.

Noninvasive assessment myocardial viability: current status and future directions

Observations of reversibility of cardiac contractile dysfunction in patients with coronary artery disease and ischemia were first made more than 40 years ago. Since that time a wealth of basic science and clinical data has been gathered exploring the mechanisms of this phenomenon of myocardial viability and relevance to clinical care of patients. Advances in cardiac imaging techniques have contributed greatly to knowledge in the area, first with thallium-201 imaging, then later with Tc-99m-based tracers for SPECT imaging and metabolic tracers used in conjunction with positron emission tomography (PET), most commonly F-18 FDG in conjunction with blood flow imaging with N-13 ammonia or Rb-82 Cl. In parallel, stress echocardiography has made great progress also. Over time observational studies in patients using these techniques accumulated and were later summarized in several meta-analyses. More recently, cardiac magnetic resonance imaging (CMR) has contributed further information in combination with either late gadolinium enhancement imaging or dobutamine stress. This review discusses the tracer and CMR imaging techniques, the pooled observational data, the results of clinical trials, and ongoing investigation in the field. It also examines some of the current challenges and issues for researchers and explores the emerging potential of combined PET/CMR imaging for myocardial viability.

Brain imaging in fibromyalgia

Fibromyalgia is a primary brain disorder or a result of peripheral dysfunctions inducing brain alterations, with underlying mechanisms that partially overlap with other painful conditions. Although there are methodologic variations, neuroimaging studies propose neural correlations to clinical findings of abnormal pain modulation in fibromyalgia. Growing evidences of specific differences of brain activations in resting states and pain-evoked conditions confirm clinical hyperalgesia and impaired inhibitory descending systems, and also demonstrate cognitive-affective influences on painful experiences, leading to augmented pain-processing. Functional data of neural activation abnormalities parallel structural findings of gray matter atrophy, alterations of intrinsic connectivity networks, and variations in metabolites levels along multiple pathways. Data from positron-emission tomography, single-photon-emission-computed tomography, blood-oxygen-level-dependent, voxel-based morphometry, diffusion tensor imaging, default mode network analysis, and spectroscopy enable the understanding of fibromyalgia pathophysiology, and favor the future establishment of more tailored treatments.

Reoperations for primary hyperparathyroidism--improvement of outcome over two decades

PURPOSE

Reoperations (R-PTX) for primary hyperparathyroidism (pHPT) are challenging, since they are associated with increased failure and morbidity rates. The aim was to evaluate the results of reoperations over two decades, the latter considering the implementation of Tc(99m)sestamibi-SPECT (Mibi/SPECT), intraoperative parathormone (IOPTH) measurement, and intraoperative neuromonitoring (IONM).

PATIENTS AND METHODS

Data of 1,363 patients who underwent surgery for pHPT were retrospectively analyzed regarding reoperations. Causes of persistent (p) pHPT or recurrent (r) pHPT, preoperative imaging studies, surgical findings, and outcome were analyzed. Data of patients who underwent surgery between 1987 and 1997 (group 1; G1) and between 1998 and 2008 (group 2; G2) with the use of Mibi/SPECT, IOPTH, and IONM were evaluated.

RESULTS

One hundred twenty-five patients with benign ppHPT (n = 108) or rpHPT (n = 17) underwent reoperations (R-PTX). Group 1 included 54, group 2 71 patients. Main cause of ppHPT (G1 = 65 % vs. G2 = 53 %) and rpHPT (G1 = 80 % vs. G2 = 60 %) was the failed detection of a solitary adenoma (p = 0.2). Group 1 patients had significantly less unilateral/focused neck re-explorations (G1 = 23 % vs. G2 = 57 %, p = 0.0001), and more sternotomies (G1 = 35 vs. G2 = 14 %, p = 0.01). After a median follow-up of 4 (range 0.9-23.4) years, reversal of hypercalcemia was achieved in 91 % (G1) and in 98.6 % in group 2 (p = 0.08, OR 7.14 [0.809-63.1]). The rates of permanent recurrent laryngeal nerve palsy (G1 = G2 = 9 %, p = 1) and of postoperative permanent hypoparathyroidism (G1 = 9 % vs. G2 = 6 %, p = 0.5) were not significantly different. Other complications such as wound infection, postoperative bleeding, and pneumonia were significantly lower in group 2 (p < 0.001).

CONCLUSION

Nowadays, cure rates of R-PTX are nearly the same as in primary operations for pHPT. These results can be achieved in high-volume centers by routine use of well-established preoperative Mibi/SPECT and US in combination with IOPTH. However, morbidity is still considerably high.

Physical attributes, limitations, and future potential for PET and SPECT

Advances in SPECT and PET imaging hardware, software, and radiotracers are vastly improving the non-invasive evaluation of myocardial perfusion and function. In contrast to traditional dual-headed, sodium iodide crystal and photomultiplier cameras with mechanical collimators, new SPECT camera designs utilize novel, collimators, and solid-state detectors that convert photons directly to electrical signals. These cameras simultaneously collect data from as many as 76 small detectors narrowly focused on the heart. New noise regularization and resolution recovery/noise reduction reconstruction software interprets emitted counts more efficiently and thus more effectively discriminates between useful signals and noise. As a result, shorter acquisition times and/or lower tracer doses produce higher quality SPECT images than were possible before. PET perfusion imaging has benefitted from the introduction of novel detectors that now allow true 3D imaging, new radiopharmaceuticals, and precise attenuation correction (AC). These developments have resulted in perfusion images with higher spatial and contrast resolution that may be acquired in shorter protocols and/or with less patient radiation exposure than traditional SPECT. Hybrid SPECT/CT and PET/CT cameras utilize transmission computed tomographic (CT) scans for AC, and offer the additional clinical advantages of evaluating coronary calcium, myocardial anatomy (including non-invasive CT angiography), myocardial function, and myocardial perfusion in a single imaging procedure.

Current research in nuclear medicine and molecular imaging in Italy: highlights of the 10th National Congress of the Italian Association of Nuclear Medicine and Molecular Imaging

The 10th National Congress of the Italian Association of Nuclear Medicine and Molecular Imaging (AIMN) took place in Rimini on March 18-21, 2011 under the chairmanship of Professor Stefano Fanti. The program was of excellent quality and put a further step for the settlement of the standardized AIMN congress structure. A large industrial exhibition demonstrated the latest technological innovations and developments within the field. The congress was a great success with more than 1100 total participants and more than 360 abstracts received. Of these, 40 abstracts were accepted for oral and 285 for poster presentations. The original investigations presented were related to different areas of nuclear medicine and molecular imaging, with particular focus on advances in instrumentation and data processing, progress in radiochemistry and pharmacy, novel diagnostics and therapeutics, and new insights in well established areas of clinical application, such as oncology, cardiology, neurology, psychiatry, endocrinology, paediatrics, and infection and inflammation. Noteworthy, several presentations at this congress, focusing on quantitative interpretation of the imaging data and on pragmatic endpoints, such as adverse outcomes, identified when nuclear medicine procedures achieved clinical effectiveness for patient care and patient management and further demonstrated that nuclear medicine plays a crucial role in the contemporary medical scenario. This highlights lecture is only a brief summary of the large amount of data presented and discussed, which can be found in much greater detail in the congress abstract book, published as volume 55, supplement 1 of the Q J Nucl Med Mol Imaging in April 2011.

Neuroimaging techniques in modern forensic psychiatry

Applied neuroscientific knowledge such as brain neuroimaging has widespread application in the medical diagnostic and treatment areas. Neuroscientific progress such as cognitive neuroscience has strong implications in specific medical fields such as forensic psychiatry. Significant progress in forensic psychiatry has affected the practice of law, in which an understanding of the complex relationship among mind, brain, and behavior is becoming necessary. Forensic psychiatry is concerned with the relationship between psychiatric abnormalities and legal violations and crimes. Due to the lack of available biological criteria, assessment, evaluation and therapy in forensic psychiatry have so far been restricted to psychosocial and mental criteria of offender personality. Recent advances in nuclear radiology such as brain imaging techniques (fMRI, DT-MRI, PET SPECT) allow a closer approach to the neural correlates of personality, moral judgments and decision-making. Introduction of neurobiological criteria (based on advanced neuroimaging techniques) in the field of forensic psychiatry and establishing the rules to what extent such biological criteria will be more reliable choice in evaluating mentally ill offenders would be of fundamental value in the modern forensic psychiatry. Psychosocial and subjective criteria in forensic evaluation will be more accomplished by biopsychosocial and objective criteria. Advances in the neuroimaging techniques bring specificity to the problems underlying the application of neuroscience to criminal law.

[Use of PET and SPECT in psychiatry]

This review presents the basic essentials of the application of nuclear medicine technology in psychiatry, i.e., positron emission tomography (PET) and single photon emission computed tomography (SPECT). These include integral principles of physics and radiochemistry as well as of data acquisition and analysis. Significant findings from applications in research and the clinical setting (schizophrenic and affective disorders, substance abuse, dementia) illustrate the huge potential of these methods. They have helped to deepen the understanding of the neurobiology of those disorders and the mechanism of action of psychotropic drugs. Due to its unmatched sensitivity, molecular imaging with PET and SPECT represents an important complement to magnetic resonance imaging technology in research and clinical practice.

Single photon emission computed tomography myocardial imaging: clinical applications and future directions

Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has proven to be an invaluable tool in the non-invasive assessment of patients with cardiovascular diseases. Exercise and pharmacologic stress SPECT MPI has been extensively studied and validated in the diagnosis and prognosis of patients with known and suspected coronary artery disease. In addition to the assessment of perfusion, electrocardiography-gated SPECT offers additional functional and volumetric information that can have significant implications on patient care. SPECT also has well-developed applications in systolic heart failure for identifying viable myocardium and predicting response to revascularization. Emerging applications of SPECT imaging include: l) phase analysis for quantitative assessment of LV dyssynchrony that may serve to improve patient selection for CRT; 2) application of heart-to-mediastinal ratio via 123I meta-iodobenzylguanidine (I-MIBG) imaging for the prediction of sudden death in patients with reduced left ventricular function, that may serve to improve patient selection for ICD therapy, and 3) use of metabolic tracers to identify the changes of ''ischemic memory'', which may help with rapid and appropriate triage of patients in the emergency room setting. SPECT MPI remains a cornerstone of clinical care that is evolving with emerging and novel applications that will continue to improve the care of patients with cardiovascular disease in the future.

Advances in SPECT imaging with respect to radionuclide therapy

Radionuclide therapy is gradually becoming more important as a therapy option in various diseases. Nuclear medicine imaging plays an important role in this, before, during and after the therapy. Single photon emission computed tomography (SPECT) imaging can be used to predict therapy response, calculate doses delivered to the tumour and the surrounding organ, check radiopharmaceutical distribution and follow-up this distribution in time. On a technological level, radionuclide imaging in a therapy setting shows some particularities and issues to be resolved. Accurate quantification is important but is hampered by attenuation, scatter from different energy peaks and from bremsstrahlung photons, septal penetration, partial volume effects etc. Some of these issues are discussed in this paper. A technique specific for therapy imaging is bremsstrahlung imaging, which can be used if the therapeutical agent is a pure beta emitter. Quantitative bremsstrahlung imaging is particularly challenging due to the complicated nature of the energy spectrum of these photons. Some work towards quantitative bremsstrahlung imaging is discussed here. Finally, some recent technical advances relevant to this field are pointed out. On the software side, Monte Carlo simulations seem to have a great potential for accurate quantitative SPECT reconstruction and subsequent patient specific image based dose calculations. Concerning hardware, the availability of SPECT-CT technology may have a large impact in imaging in radionuclide therapy. Novel detector technologies such as solid-state detectors may also prove to have significant advantages in this field.

Diagnostic value of left ventricular function after adenosine triphosphate loading and at rest in the detection of multi-vessel coronary artery disease using myocardial perfusion imaging

BACKGROUND

Although transient left ventricular (LV) dilation is a well-known marker for extensive coronary artery disease (CAD), few studies performed quantitative analysis of LV function of post adenosine triphosphate (ATP) stress and at rest to detect extensive CAD.

METHODS

One hundred nineteen patients with suspected CAD underwent post-stress and resting gated single-photon emission computed tomography (SPECT). Myocardial perfusion was assessed with a 20-segment model, and the changes in LV volume and function with ATP were analyzed. In addition, the stress-induced volume ratio (SIVR), defined as stress-to-rest ratios (end-systolic volume x 5 + end-diastolic volume), was calculated. All the patients underwent coronary angiography within 3 months of gated SPECT.

RESULTS

In the 62 patients with multi-vessel CAD, the summed stress score (SSS) (16.6 +/- 8.7 vs 11.5 +/- 9.1; P < .002), summed difference score (SDS) (9.6 +/- 5.8 vs 3.9 +/- 4.2; P < .0001), the post-stress increase in end-diastolic volume (EDV) (7.7 +/- 7.9 vs 2.2 +/- 5.3 mL; P < .0001), the post-stress increase in end-systolic volume (ESV) (9.4 +/- 6.0 vs 2.7 +/- 4.0 mL; P < .0001), and the (SIVR) (1.21 +/- 0.14 vs 1.06 +/- 0.10; P < .0001) were greater than in the 57 patients with insignificant or single-vessel CAD, whereas the post-stress increase in ejection fraction (EF) was less (-6.0 +/- 4.9 vs -2.0 +/- 4.4%; P < .0001). In the detection of multi-vessel CAD, an SSS of > or = 14 and an SDS of > or = 9 showed sensitivities of 57% and 52%, respectively, and specificities of 63% and 88%, respectively, while increase in EDV of > or = 6 mL, increase in ESV of > or = 6 mL, decrease in EF of > or = 5% after stress, and SIVR of > or = 1.13 demonstrated sensitivities of 60%, 81%, 60%, and 74% and specificities of 74%, 77%, 77%, and 79%, respectively. The multivariate discriminant analysis revealed that the combination of post-stress increase in ESV and the SDS best identified multi-vessel CAD, with 81% sensitivity and 77% specificity (chi(2) = 63.6), whereas the SDS alone showed 52% sensitivity and 88% specificity (chi(2) = 22.4).

CONCLUSIONS

The addition of "post-ATP stress" and "at rest" LV functional analysis using gated SPECT to conventional perfusion analysis helps to better identify patients with multi-vessel CAD.

Recent advances in nuclear cardiology

Nuclear cardiology is an essential part of functional, non-invasive, cardiac imaging. Significant advances have been made in nuclear cardiology since planar (201)thallium ((201)TI) scintigraphy was introduced for the evaluation of left ventricular (LV) perfusion nearly 40 years ago. The use of nuclear cardiology has been steadily increasing over the last 20 years with important steps being the introduction of (99m)technetium- ((99m)Tc)-labelled perfusion radiotracers, the change from only planar to now much more single photon emission computed tomography (SPECT) and positron emission tomography (PET), electrocardiogram gating of nuclear perfusion imaging, and finally introducing nuclear hybrid imaging using either SPECT or PET together with either computed tomography or magnetic resonance imaging. The indications have extended from nearly only coronary artery diseases to several non-coronary cardiac diseases. The advances in nuclear cardiology are discussed under the four headlines of: 1) myocardial perfusion, 2) cardiac performance including LV and right ventricular (RV) function, 3) myocardial metabolism, and 4) experimental nuclear cardiology.

SPECT neuroimaging in translational research of CNS disorders

High resolution SPECT imaging is an emerging field and there are only limited studies as yet available in this direction. Still there is continuous effort to achieve better spatial and temporal resolution in order to obtain detailed structural and functional information of different brain regions in small experimental animals. Recently, SPECT imaging system has been used to perform in vivo imaging using specific radioligands to further elucidate the role of dopaminergic, serotonergic, and cholinergic neurotransmission in relation to regional cerebral blood flow in various human CNS disorders and in gene-manipulated mouse models of neurodegeneration. Although in vivo and non-invasive translational research can be performed by high-resolution microPET imaging system, its limited spatial resolution restricts detailed anatomical and functional information of different brain regions involved in disease process. Recently developed NanoSPECT/CT imaging system has a better spatial resolution hence can be used to correlate and confirm microPET imaging data and determine the precise structural and functional anatomy of CNS disorders and their remission. Moreover SPECT imaging system reduces the cost and number of animals and provides detailed information of CNS disorders at the cellular, molecular and genetic level. Furthermore, SPECT system is economical, provides less radiation burden, and can be used to study bio-distribution of newly synthesized radioligands with increased target to non-target ratios, quality control, and clinical applications. It is envisaged that high-resolution SPECT imaging system will further improve in vivo non-invasive translational research on CNS disorders of unknown etiopathogenesis and their treatment in future.

[Myocardial perfusion scintigraphy 2006 in Germany. Results of the query and current status]

AIM

This second survey was to deliver further information on myocardial perfusion scintigraphy (MPS) in Germany in 2006.

METHOD

351 questionnaires were evaluated: 207 private practices (PP), 117 hospitals (HO), 27 from university hospitals (UH).

RESULTS

MPS of 106 331 patients were reported, 85% were investigated with (99m)Tc-perfusion tracers. 74% [2005 = 72%] were performed in PP, 17% [2005 = 15%] in HO and 9% [2005 = 13%] in UH. PP, which participated in 2005 and 2006, demonstrated an increase by 3,9% (HO 0%, UH - 13,0%). The type of stress was pharmacological in 27% [2005 = 22%]; 54% adenosine (of these 29% with exercise), 37% dipyridamole (of these 56% with exercise), and 9% dobutamine. Gated SPECT was performed in 42% [2005 = 36%] of all rest- and in 39% [2005 = 32%] of all stress MPS. An attenuation correction was used by 69 [2005 = 78] institutions. 40% of all MPS were performed in patients suspected to have CAD. 24% of all institutions reported changes in the use of MPS by competing methods.

CONCLUSION

There is a small increase of MPS between 2005 and 2006 despite competing methods. Gated SPECT has experienced more acceptance. Suspicion of CAD is an important indication of MPS. In order to tap the full potential of MPS a gated SPECT should be performed routinely.

Bone scan update

The radionuclide bone scan is one of the most commonly performed pediatric nuclear medicine procedures. Bone scintigraphy is used as the diagnostic procedure of choice for diagnosis of bone and soft-tissue infection and can aid in the diagnosis of occult trauma without radiographic findings. There is a complimentary role for bone scintigraphy in the assessment of a child with suspected nonaccidental injury. The use of bone scan in a child with unexplained bone pain or limp may provide a diagnosis that could be related to trauma, tumor, or inflammation. A negative bone scan can help relieve concern for significant pathology. Bone scans in children require careful attention to technique to obtain high-quality diagnostic images. Routine whole-body imaging, magnification, additional views, and the use of single-photon emission computed tomography also are a routine part of this examination in children. Correlation with conventional radiographs is mandatory, and the judicious use of hybrid imaging with the addition of computed tomography may further improve diagnostic acumen, confidence and accuracy. New radiopharmaceuticals such as fluorine-18 may also play a role in changing techniques for pediatric bone scintigraphy.