Quantification of bone metabolic activity in the natural course of fractural lesions measured by quantitative SPECT/CT.

Objectives: While increased uptake at the bone fractural site gradually decreases over time on bone scans, the rate of change has not been quantitatively evaluated. The purpose of this study was to quantify the extent of bone metabolic changes in fractural lesions on bone SPECT/CT. Methods: We reviewed bone scans acquired by dedicated SPECT/CT and chose those scans in which quantitative SPECT/CT of the same range was acquired twice or more. We set the region of interest on lesions of bone fracture and degeneration, and measured the maximum standardized uptake value (SUVmax). From the SUVmax of lesions and the interval between scans, a value for 30-day change in SUVmax was calculated as ∆SUVmax30d. The relationship between preSUVmax, SUVmax for the first scan of the comparison, and ∆SUVmax30d was evaluated utilizing a linear least-squares method. Furthermore, we assessed the ability to differentiate between fracture and degeneration using receiver operating characteristics (ROC) analysis and the Mann-Whitney U test. All cases were then categorized into five groups according to preSUVmax. Values of p <0.05 were considered statistically significant. Results: We investigated 175 scans from 60 patients and analyzed scan combinations for 157 fractural lesions and 266 degenerative lesions. The relationship between preSUVmax of fractural lesions and ∆SUVmax30d was approximated as ∆SUVmax30d =-0.15×preSUVmax +1.35 (R 2=0.60, p<0.0001). Area under the curves for all cases, 30≤ preSUVmax, 20≤ preSUVmax <30, 15≤ preSUVmax <20, 10≤ preSUVmax <15, and preSUVmax <10 were 0.73, 0.89, 0.86, 0.80, 0.91, and 0.59, respectively. Median ∆SUVmax30d was significantly lower at fractural lesions than at degenerative lesions (-0.62 vs -0.04; p <0.0001). As for analyses of groups divided by preSUVmax, all median ∆SUVmax30d for fractural lesions were significantly lower than those of degenerative lesions except for the group with preSUVmax <10. Conclusion: The increased uptake at the fractural bone lesion observed in the quantitative bone SPECT/CT gradually decreased at the rate of SUV 0.15 per month, which showed a different trend with degenerative change.

Atlas of non-pathological solitary or asymmetrical skeletal muscle uptake in [18F]FDG-PET.

Positron emission tomography (PET) using 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is widely used in oncology and other fields. In [18F]FDG PET images, increased muscle uptake is observed owing exercise load or muscle tension, in addition to malignant tumors and inflammation. Moreover, we occasionally observe non-pathological solitary or unilateral skeletal muscle uptake, which is difficult to explain the strict reason. In most cases, we can interpret them as not having pathological significance. However, it is important to recognize such muscle uptake patterns to avoid misdiagnoses with pathological ones. Therefore, the teaching point of this pictorial essay is to comprehend the patterns of solitary or asymmetrical skeletal muscle uptake seen in routine [18F]FDG-PET scans. As an educational goal, you will be able to mention muscles where intense physiological [18F]FDG uptake can be observed, differentiate between physiological muscle uptake and lesion, and discuss with any physicians or specialists about uncertain muscle uptake.

Satisfied quantitative value can be acquired by short-time bone SPECT/CT using a whole-body cadmium-zinc-telluride gamma camera.

The aim of this study was to evaluate the quantitative values of short-time scan (STS) of metastatic lesions compared with a standard scan (SS) when acquired by whole-body bone SPECT/CT with cadmium-zinc-telluride (CZT) detectors. We retrospectively reviewed 13 patients with bone metastases from prostate cancer, who underwent SPECT/CT performed on whole-body CZT gamma cameras. STSs were obtained using 75, 50, 25, 10, and 5% of the list-mode data for SS, respectively. Regions of interest (ROIs) were set on the increased uptake areas diagnosed as metastases. Intraclass correlation coefficients (ICCs) of standardized uptake values (SUVs) for the ROIs were calculated between the SS and each STS, and ICC ≥ 0.8 was set as a perfect correlation. Moreover, the repeatability coefficient (RC) was calculated, and RC ≤ 20% was defined as acceptable. A total of 152 metastatic lesions were included in the analysis. The ICCs between the SS vs. 75%-STS, 50%-STS, 25%-STS, 10%-STS, and 5%-STS were 0.999, 0.997, 0.994, 0.983, and 0.955, respectively. The RCs of the SS vs. 75%-STS, 50%-STS, 25%-STS, 10%-STS, and 5%-STS were 7.9, 12.4, 19.8, 30.8, and 41.3%, respectively. When evaluating the quality of CZT bone SPECT/CT acquired by a standard protocol, 25%-STS may provide adequate quantitative values.

Can the function of the tubarial glands be evaluated using [99mTc]pertechnetate SPECT/CT, [18F]FDG PET/CT, and [11C]methionine PET/CT?

BACKGROUND: The tubarial glands (TGs) are recently reported as newly found salivary gland structures that can be organs at risk predominantly localized in the tori tubarius in the nasopharynx using prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT). The aims of this study were to analyze uptake in the TGs compared with that in the other salivary glands and palatine tonsils using [99mTc]pertechnetate SPECT/CT, [18F]FDG PET/CT, and [11C]methionine PET/CT and to confirm whether these three imaging modalities are useful in evaluating the physiological function of the TGs. Twelve and 130 patients, who underwent [99mTc]pertechnetate SPECT/CT and [18F]FDG/[11C]methionine PET/CT, respectively, were retrospectively included. [99mTc]pertechnetate uptake in the tori tubarius was visually assessed and semiquantitatively compared with that in the background, parotid salivary glands (PSGs), submandibular salivary glands (SmSGs), and sublingual salivary glands (SlSGs). Correlations of [18F]FDG and [11C]methionine uptakes in the tori tubarius with those in the other three salivary glands and palatine tonsils were analyzed. RESULTS: [99mTc]pertechnetate uptake in the tori tubarius was invisible and was not significantly higher than that in the background. Both [18F]FDG and [11C]methionine uptakes in the tori tubarius were correlated with that in the palatine tonsils (r = 0.56, p < 0.0001; r = 0.48, p < 0.0001, respectively). [18F]FDG uptake in the tori tubarius was not positively correlated with that in the PSGs, SmSGs, and SlSGs (r = - 0.19, p = 0.03; r = - 0.02, p = 0.81; r = 0.12, p = 0.17, respectively). [11C]methionine uptake in the tori tubarius was correlated with that in the SmSGs and SlSGs (r = 0.24, p = 0.01; r = 0.32, p < 0.01, respectively), but not with that in the PSGs (r = 0.16, p = 0.08). CONCLUSIONS: The TGs were undetectable on [99mTc]pertechnetate SPECT/CT. Both [18F]FDG and [11C]methionine uptakes in the tori tubarius were clearly affected by that in the palatine tonsils and was little related to that in the other salivary glands. Therefore, it seems difficult to evaluate the physiological function of the TGs as salivary glands using [99mTc]pertechnetate SPECT/CT, [18F]FDG PET/CT, and [11C]methionine PET/CT imaging.

Microvascular function measurement in mice: From large to small.

There is a growing body of interest in cardiac microvascular function because it plays an important role in various cardiac disease conditions. Therefore, efforts have been made to develop non-invasive techniques to measure microvascular function. In this issue of the journal, Guerraty et al developed a micro-SPECT-based approach to assess microvascular function in in vivo mice. They applied two independent approaches to measure microvascular function: (1) myocardial blood flow measurement using 99mTc-sestamibi as a flow tracer and (2) intramyocardial blood volume measurement using 99mTc-red blood cells. Although there are issues to be addressed, they provided an important framework for non-invasive assessment of microvascular function in mice, where a number of disease models are readily available. Thus, their approaches are encouraging for facilitating better understanding of pathophysiology underlying microvascular disease models, and thereby the development of therapeutic options in future.

Feasibility of simultaneous 99mTc-tetrofosmin and 123I-BMIPP dual-tracer imaging with cadmium-zinc-telluride detectors in patients undergoing primary coronary intervention for acute myocardial infarction.

BACKGROUND: Simultaneous dual-tracer imaging using isotopes with close photo-peaks may benefit from improved properties of cadmium-zinc-telluride (CZT)-based scanners. METHODS: Thirty patients having undergone primary percutaneous coronary intervention for acute myocardial infarction underwent single-(99mTc-tetrofosmin (TF) or 123I-BMIPP first) followed by simultaneous 99mTc-TF /123I-BMIPP dual-tracer imaging using a Discovery NM/CT 670 CZT. The values for the quantitative gated-SPECT (QGS) and the quantitative perfusion SPECT (QPS) were assessed. RESULTS: The intra-class correlation (ICC) coefficients between the single- and dual-tracer imaging were high in all the QGS and QPS data (Summed motion score: 0.95, summed thickening score: 0.94, ejection fraction: 0.98, SRS for 99mTc-TF: 0.97/ for 123I-BMIPP: 0.95). Wall motion, wall thickening and rest scores per coronary-territory-based regions were also comparable between the single- and dual imaging (ICC coefficient > 0.91). The interrater concordance in the visual analysis for the infarction and perfusion-metabolism mismatch was significant for the global and regional left ventricle (P < 0.001). CONCLUSION: The quantitative/semi-quantitative values for global and regional left-ventricular function, perfusion, and fatty acid metabolism were closely comparable between the dual-tracer imaging and the single-tracer mode. These data suggests the feasibility of the novel CZT-based scanner for the simultaneous 99mTc-TF /123I-BMIPP dual-tracer acquisitions in clinical settings.

A new computerized assessment battery for cognition (C-ABC) to detect mild cognitive impairment and dementia around 5 min.

This study aimed to develop a new computerized assessment battery for cognition (C-ABC) to detect mild cognitive impairment (MCI) and dementia. We performed C-ABC in subjects with dementia (n = 422), MCI (n = 145), and normal cognition (NC; n = 574), and analyzed by age stratum (50s, 60s, and 70-85 years). To distinguish MCI from NC, the C-ABC total combined score, which were calculated by dividing the C-ABC total score by the C-ABC required time, revealed the best area under the curves (AUC) at 0.838 and 0.735 in the 50s and 60s age groups, respectively; notably, this entire procedure took approximately 5 min. To distinguish dementia from NC and MCI, the partial items of C-ABC (items 3 + 6 combined score) revealed the best AUCs at 0.910, 0.874, and 0.882 in the 50s, 60s, and 70-85 age groups, respectively. Furthermore, the items 3 + 6 combined score established the best AUC at 0.794 in the 70-85 age group to distinguish MCI from NC; this entire procedure took around 2 min. Hence, this study suggests that C-ABC could be a useful tool for detecting dementia or MCI in a short time.

Cardiac Amyloidosis: Current Diagnostic Strategies Using Multimodality Imaging.

Amyloidosis is a systemic disorder in which abnormal amyloid proteins deposit in body organs, leading to organ dysfunction and death. Cardiac amyloid deposition, causing a sort of restrictive cardiomyopathy and associated with increased risk of mortality. Most cases of cardiac amyloidosis are of either light chain or transthyretin type. Early and accurate diagnosis of cardiac amyloidosis may improve outcomes. However, diagnosis requires systematic approach including electrocardiography and biomarkers when encountered suspicious candidate. Diagnosis by multimodality noninvasive imaging have been substantially studied and established for differentiation from subtypes. Recent advance in the treatment of amyloidosis offers therapeutic monitoring and prognosis.

Postconditioning Accelerates Myocardial Inflammatory Resolution Demonstrated by 14C-Methionine Imaging and Attenuates Ventricular Remodeling After Ischemia and Reperfusion.

BACKGROUND: Methionine uptake after myocardial infarction has been proven to reflect myocardial inflammation. The effect of postconditioning on the post-infarction inflammatory process, however, remains to be elucidated.Methods and Results:In control (n=22) and postconditioning rats (n=23), the left coronary artery was occluded for 30 min, followed by reperfusion for 1, 3, 7, and 14 days. Postconditioning was performed immediately following the reperfusion. 14C-methinine (0.74 MBq) and 201Tl (14.8 MBq) were injected 20 and 10 min prior to sacrifice, respectively. One minute before sacrifice, 150-180 MBq of 99 mTc-MIBI was injected immediately following the re-occlusion of the left coronary artery to verify the area at risk, and left ventricular triple-tracer autoradiography was performed. To examine the ventricular remodeling, echocardiography was performed 2 months after reperfusion in both groups (n=6 each). In the control rats, the methionine uptake ratios on days 1, 3, 7, and 14 were 0.74±0.12, 1.85±0.16, 1.48±0.10, 1.25±0.04, respectively. With postconditioning, methionine uptake was similar on day 3 (1.90±0.21), but was lower on day 7 (1.23±0.22, P<0.05) and day 14 (1.08±0.09, P<0.005). Echocardiography revealed that postconditioning reduced the ventricular end-diastolic (0.97±0.16 to 0.78±0.12 cm, P<0.05) and systolic (0.85±0.21 to 0.55±0.23 cm, P<0.05) dimensions and improved ventricular percentage fractional shortening (12±6.2 to 29±12 %, P=0.01). CONCLUSIONS: 14C-methinine imaging revealed that postconditioning accelerated resolution of inflammation and attenuated ventricular remodeling.

Shortened acquisition time in simultaneous 99mTc-tetrofosmin and 123I-ß-methyl-p-iodophenyl pentadecanoic acid dual-tracer imaging with cadmium-zinc-telluride detectors in patients undergoing primary coronary intervention for acute myocardial infarction.

OBJECTIVE: The use of cadmium-zinc-telluride-based scanners may increase the clinical feasibility of simultaneous dual-isotope imaging. In the current study, we sought to investigate a potential acquisition time in simultaneous Tc-tetrofosmin/I-ß-methyl-p-iodophenyl pentadecanoic acid dual-isotope imaging using a Discovery NM/CT 670 cadmium-zinc-telluride. METHODS: Simultaneous Tc-tetrofosmin/I-ß-methyl-p-iodophenyl pentadecanoic acid dual-isotope imaging was performed in 29 patients who had undergone primary percutaneous coronary intervention for acute myocardial infarction. Referenced images with an acquisition time of 65 s/view (16.25 min) were reframed to produce images with acquisition times of 33, 16, and 8 s/view. The values for the quantitative-gated single-photon emission computed tomography (SPECT) and the quantitative perfusion SPECT were compared. RESULTS: The quantitative-gated SPECT values for images with 33, 16, and 8 s/views showed good consistency with those for 65 s/view (the lower 95% confidence intervals for the intraclass correlation were ≥0.80). The quantitative perfusion SPECT values for Tc-tetrofosmin images with 33, 16, and 8 s/views also showed good consistency with those for 65 s/view; however, the quantitative perfusion SPECT values for I-ß-methyl-p-iodophenyl pentadecanoic acid images with an acquisition time of 8 s/view were not consistent with the reference acquisition time of 65 s/view. CONCLUSIONS: The quantitative-gated SPECT and quantitative perfusion SPECT values obtained from images with shorter acquisition times correlated with the values obtained from images with a reference acquisition time of 65 s/view; however, tracer-specific predisposition should be considered. These findings suggest that it is possible to reduce acquisition time when performing simultaneous Tc-tetrofosmin/I-ß-methyl-p-iodophenyl pentadecanoic acid dual-tracer imaging with the novel cadmium-zinc-telluride scanner.

Ultrafast bone scintigraphy scan for detecting bone metastasis using a CZT whole-body gamma camera.

PURPOSE: To evaluate the feasibility of short whole-body bone scan acquisition times using a novel gamma camera with cadmium-zinc-telluride (CZT) semiconductor detectors. METHODS: We retrospectively enrolled 78 consecutive patients with prostate cancer who underwent bone scintigraphy using a whole-body gamma camera with CZT detectors. After acquisition of list-mode data with 180 s per bed position, anterior and posterior whole-body images were reconstructed using the first 5%, 10%, 25%, 50%, 75% and 100% of the list-mode data. Two experienced nuclear medicine physicians interpreted the images, and interrater agreement and the diagnostic value of the images were determined. Quantitative artificial neural network (ANN) values, bone scan indexes (BSI) and hotspot numbers (HsN) were also calculated by automated diagnostic software. RESULTS: Excellent interrater reliabilities of the visual assessments were obtained for the 100%, 75%, 50%, and 25% images (κ = 0.88, 0.88, 0.88 and 0.88, respectively). The 5% images also showed high diagnostic value (sensitivity 0.94, specificity 0.84 and accuracy 0.86). Intraclass correlation coefficients (ICC) between the 100% images and the reduced acquisition time images were evaluated in quantitative analyses, and excellent correlations were observed for ANN value in the 75% images (ICC 0.77), for BSI in all the reduced acquisition time images (75%, 50%, 25%, 10% and 5%; ICC 0.99, 0.99, 0.99, 0.96 and 0.75, respectively), and for HsN in the 75%, 50%, 25% and 10% images (ICC 0.99, 0.99, 0.98 and 0.90, respectively). CONCLUSION: Whole-body gamma cameras with CZT detectors have the potential to reduce image acquisition times and the dose of radioisotope injected for bone scans.

High-speed scanning of planar images showing 123I-MIBG uptake using a whole-body CZT camera: a phantom and clinical study.

BACKGROUND: The heart-to-mediastinum ratio (HMR) obtained in myocardial sympathetic innervation imaging using 123I-metaiodobenzylguanidine (MIBG) is used for heart failure or Lewy body diseases (LBD). Discovery NM/CT 670 CZT, a novel whole-body scanner, enables direct HMR measurements in planar images, in contrast to cardiac-dedicated CZT-based cameras which require specific post-processing reconstruction. We sought to investigate the clinical utility of the Discovery NM/CT 670 CZT for myocardial innervation imaging and the potential time reduction. RESULTS: Following preliminary phantom examinations, 123I-MIBG planar imaging was performed in 36 patients with suspected or known LBD to measure HMRs with a collection time of 300 s. Images for different collection times were subsequently reframed using already acquired data, and changes in HMRs were evaluated. The HMRs for patients with versus without clinically diagnosed LBD were 1.63 ± 0.08 versus 2.21 ± 0.08 at early phase (p < 0.001) and 1.54 ± 0.09 versus 2.08 ± 0.09 at delayed phase (p < 0.001). The difference of HMRs (300 s - other collection time) became greater as the collection time became shorter. There was good consistency in HMRs between the 300-s images (reference) and the 200-s (intra-class correlation (ICC) coefficients > 0.99), 100-s (ICC coefficients > 0.97), and 50-s (ICC coefficients > 0.89) images. CONCLUSIONS: In planar images with a whole-body CZT-based camera, the HMRs of patients with LBD were significantly lower than those without. HMRs with the collection time of 50 s and longer showed good consistency with those of 300 s in the ICC analysis. These findings indicate a clinical utility of this novel scanner for HMR measurements and potential time reductions.

How do we establish cardiac sympathetic nervous system imaging with 123I-mIBG in clinical practice? Perspectives and lessons from Japan and the US.

Cardiac denervation is associated with progressive left ventricular (LV) dysfunction, ventricular arrhythmias, and sudden cardiac death (SCD) in heart failure (HF). In this regard, it is important to evaluate cardiac-specific sympathetic nervous system (SNS) function. The radiotracer Iodine-123 meta-iodobenzylguanidine (123I-mIBG) can noninvasively evaluate pre-synaptic SNS function. Recent multicenter trials have shown 123I-mIBG to have strong predictive value for fatal arrhythmias and cardiac death in HF. 123I-mIBG was initially developed in the USA in the 1970s. In 1992, the Japanese Ministry of Health and Labour approved 123I-mIBG for the assessment of cardiac function. Following approval, the Japanese nuclear cardiology community developed 123I-mIBG imaging services in various medical centers. Japanese groups have been trying to establish the clinical utility of 123I-mIBG and standardize parameters for data acquisition and image analysis. The US Food and Drug Administration (FDA) has approved clinical use of 123I-mIBG for cardiac and non-cardiac imaging. However, clinical use of 123I-mIBG in the US has been very limited. The number of 123I-mIBG studies in Japan has also been limited. There are similarities and differences between the two countries. To establish the clinical utility of 123I-mIBG in both countries, it is important to characterize the situations of 123I-mIBG in each.

Quantification of osteoblastic activity in epiphyseal growth plates by quantitative bone SPECT/CT.

OBJECTIVE: Quantifying the function of the epiphyseal plate is worthwhile for the management of children with growth disorders. The aim of this retrospective study was to quantify the osteoblastic activity at the epiphyseal plate using the quantitative bone SPECT/CT. MATERIALS AND METHODS: We enrolled patients under the age of 20 years who received Tc-99m hydroxymethylene diphosphonate bone scintigraphy acquired by a quantitative SPECT/CT scanner. The images were reconstructed by ordered subset conjugate-gradient minimizer, and the uptake on the distal margin of the femur was quantified by peak standardized uptake value (SUVpeak). A public database of standard body height was used to calculate growth velocities (cm/year). RESULTS: Fifteen patients (6.9-19.7 years, 9 female, 6 male) were enrolled and a total of 25 legs were analyzed. SUVpeak in the epiphyseal plate was 18.9 ± 2.4 (average ± standard deviation) in the subjects under 15 years and decreased gradually by aging. The SUVpeak correlated significantly with the age- and sex-matched growth velocity obtained from the database (R2 = 0.83, p < 0.0001). CONCLUSION: The SUV measured by quantitative bone SPECT/CT was increased at the epiphyseal plates of children under the age of 15 years in comparison with the older group, corresponding to higher osteoblastic activity. Moreover, this study suggested a correlation between growth velocity and the SUV. Although this is a small retrospective pilot study, the objective and quantitative values measured by the quantitative bone SPECT/CT has the potential to improve the management of children with growth disorder.

Cerebral Amyloid Angiopathy-Related Microbleeds and Cerebrospinal Fluid Biomarkers in Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) commonly accompanies cerebral amyloid angiopathy (CAA). OBJECTIVE: We aimed to reveal associations between CAA-related brain microbleeds and cerebrospinal fluid (CSF) markers in AD patients. METHODS: Patients with probable AD (n = 88) from consecutive patients in our memory clinic were evaluated for patient demographics, vascular risk factors, neuropsychological tests, apolipoprotein E phenotype, MRI including T2*-weighted image and fluid attenuated inversion recovery sequence, and CSF amyloid and tau markers. RESULTS: The 88 patients with AD included 15 with microbleeds only in cortical/subcortical regions (cortical microbleeds) that could be CAA-related, 16 with microbleeds only in deep locations (deep microbleeds), 3 with microbleeds in both cortical and deep locations (mixed microbleeds), and 54 without microbleeds. The CSF levels of amyloid ß-protein 1-40 (Aß40) and amyloid ß-protein 1-42 (Aß42) were significantly lower in patients with cortical microbleeds than in those without microbleeds (p = 0.001 and p = 0.027, respectively). The result remained unchanged after adjustment for age, sex, apolipoprotein E E4 presence, and leukoaraiosis. CONCLUSIONS: CAA-related cortical microbleeds would be associated with lower CSF levels of Aß40 and Aß42 in AD, reflecting the deposition of both Aß40 and Aß42 in the cerebrovasculature.

Comparison of Dopamine Transporter SPECT and 123I-MIBG Myocardial Scintigraphy to Assess Clinical Severity in Patients With Parkinson Disease.

PURPOSE: The aim of our study was to evaluate the use of dopamine transporter (DAT) SPECT and I-MIBG myocardial scintigraphy to determine the clinical severity of Parkinson disease (PD), with a focus on motor impairments affecting activities of daily living (ADLs). METHODS: Data for 65 consecutive PD patients who underwent both DAT and MIBG imaging were reviewed. Associations between imaging variables and Hoehn and Yahr (H&Y) staging or self-supportive care ratings were investigated. Univariate and multivariate regression analyses were performed to determine the factors associated with ADLs. RESULTS: After applying the exclusion criteria, 45 patients were analyzed (age, 73.1 ± 9.3 years; 23 males; H&Y stage 1: n = 12, stage 2: n = 14, stage 3: n = 10, stage 4: n = 5, and stage 5: n = 4; self-supportive care rating-dependent ADLs: n = 29). Dopamine transporter variables were significantly associated with the clinical severity of PD as assessed by H&Y staging, whereas MIBG variables were not. Dopamine transporter variables gradually decreased throughout progressive stages, whereas the MIBG variables changed only in the advanced stages. In a multivariate analysis including clinical and imaging variables, both lower DAT and MIBG uptakes were significantly associated with dependent ADL status (P = 0.028 and 0.034, respectively). CONCLUSIONS: In patients with PD, DAT SPECT and MIBG myocardial scintigraphy were associated with ADL status; DAT SPECT was a stronger indicator of severity than MIBG myocardial scintigraphy in the early and middle stages.

Prediction of all-cause death using (11)C-hydroxyephedrine positron emission tomography in Japanese patients with left ventricular dysfunction.

OBJECTIVES: The aim of this study was to determine whether (11)C-hydroxyephedrine ((11)C-HED) can predict adverse events including all-cause death in Japanese patients with left ventricular (LV) dysfunction. BACKGROUND: Although (11)C-HED PET has been used to assess cardiac sympathetic innervation in various disease conditions, data on their prognostic value are limited. METHODS: Sixty patients (mean LVEF, 42 ± 14 %) with LV dysfunction (42 ischemic and 18 non-ischemic heart disease) underwent (11)C-HED PET. Myocardial retention was calculated for (11)C-HED PET as a measure of cardiac sympathetic neuronal integrity. Statistical analysis was performed using Cox proportional hazards regression and log-rank test. RESULTS: Thirteen deaths (7 cardiac and 6 non-cardiac deaths) occurred during a mean follow-up period of 33 ± 23 months. The patients with death were associated with significantly lower (11)C-HED retention (7.1 ± 2.1 vs 9.0 ± 2.4, p = 0.015) than those without death. The hazard ratio for global (11)C-HED retention per unit (/min) was 0.762 (p = 0.039), which remained significant in multivariate analysis. When the patients were divided into the high (≥8.5) and low (<8.5) (11)C-HED retention groups, the low (11)C-HED retention group was associated with significantly poorer survival than the high (11)C-HED retention group (p = 0.004). CONCLUSION: The low global (11)C-HED retention is a marker of poor overall survival in patients with LV dysfunction in this study.

Simultaneous acquisition of (99m)Tc- and (123)I-labeled radiotracers using a preclinical SPECT scanner with CZT detectors.

OBJECTIVE: Simultaneous acquisition of (99m)Tc and (123)I was evaluated using a preclinical SPECT scanner with cadmium zinc telluride (CZT)-based detectors. METHODS: 10-ml cylindrical syringes contained about 37 MBq (99m)Tc-tetrofosmin ((99m)Tc-TF) or 37 MBq (123)I-15-(p-iodophenyl)-3R,S-methyl pentadecanoic acid ((123)I-BMIPP) were used to assess the relationship between these SPECT radioactive counts and radioactivity. Two 10-ml syringes contained 100 or 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP to assess the influence of (99m)Tc upscatter and (123)I downscatter, respectively. A rat-sized cylindrical phantom also contained both 100 or 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP. The two 10-ml syringes and phantom were scanned using a pinhole collimator for rats. Myocardial infarction model rats were examined using 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP. Two 1-ml syringes contained 105 MBq (99m)Tc-labeled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) and 35 MBq (123)I-labeled N-ω-fluoropropyl-2ß-carbomethoxy-3ß-(4-iodophenyl) nortropane ((123)I-FP-CIT). The two 1-ml syringes were scanned using a pinhole collimator for mice. Normal mice were examined using 105 MBq (99m)Tc-HMPAO and 35 MBq (123)I-FP-CIT. RESULTS: The relationship between SPECT radioactive counts and radioactivity was excellent. Downscatter contamination of (123)I-BMIPP exhibited fewer radioactive counts for 300 MBq (99m)Tc-TF without scatter correction (SC) in 125-150 keV. There was no upscatter contamination of (99m)Tc-TF in 150-175 keV. In the rat-sized phantom, the radioactive count ratio decreased to 4.0 % for 300 MBq (99m)Tc-TF without SC in 125-150 keV. In the rats, myocardial images and radioactive counts of (99m)Tc-TF with the dual tracer were identical to those of the (99m)Tc-TF single injection. Downscatter contamination of (123)I-FP-CIT was 4.2 % without SC in 125-150 keV. In the first injection of (99m)Tc-HMPAO and second injection of (123)I-FP-CIT, brain images and radioactive counts of (99m)Tc-HMPAO with the dual tracer in normal mice also were the similar to those of the (99m)Tc-HMPAO single injection. In the first injection of (123)I-FP-CIT and second injection of (99m)Tc-HMPAO, the brain images and radioactive counts with the dual tracer were not much different from those of the (123)I-FP-CIT single injection. CONCLUSIONS: Dual-tracer imaging of (99m)Tc- and (123)I-labeled radiotracers is feasible in a preclinical SPECT scanner with CZT detector. When higher radioactivity of (99m)Tc-labeled radiotracers relative to (123)I-labeled radiotracers is applied, correction methods are not necessarily required for the quantification of (99m)Tc- and (123)I-labeled radiotracers when using a preclinical SPECT scanner with CZT detector.

Correlation between apoptosis and left ventricular remodeling in subacute phase of myocardial ischemia and reperfusion.

BACKGROUND: To investigate whether an apoptotic process demonstrated by (99m)Tc-annexin-V ((99m)Tc-AV) uptake correlates with left ventricular remodeling (LVR) after myocardial infarction, we assessed (99m)Tc-AV uptake in rat model of myocardial ischemia and reperfusion. METHODS: The left coronary artery (LCA) of 15 rats was occluded for 20 to 30 min, followed by reperfusion. After 2 weeks, (99m)Tc-AV was injected, and then 1 h later, (201)Tl was injected after reocclusion of the LCA. Dual-tracer autoradiography was performed to assess (99m)Tc-AV uptake and the area at risk (AAR) by (201)Tl defect. (99m)Tc-AV uptake ratio was calculated by dividing the count density of the AAR by that of the normally perfused area. In short-axis LV slices, LV cavity dilation index (DI) was calculated by dividing the area of LV cavity by that of the whole LV area. LV wall-thinning ratio (WTR) was calculated by dividing the LV wall thickness in the AAR by that of the normally perfused area. RESULTS: Significant (99m)Tc-AV uptake in the AAR was observed in 10 rats. DI was significantly higher in rats with positive (99m)Tc-AV uptake than in rats without uptake. WTR was smaller in rats with positive (99m)Tc-AV uptake than in rats without uptake. CONCLUSIONS: The data suggest (99m)Tc-AV uptake in injured myocardium might correlate with LVR at 2 weeks after myocardial ischemia and reperfusion.