Detection of current-sheet and bipolar ion flows in a self-generated antiparallel magnetic field of laser-produced plasmas for magnetic reconnection research

Magnetic reconnection in laser-produced magnetized plasma is investigated by using optical diagnostics. The magnetic field is generated via the Biermann battery effect, and the inversely directed magnetic field lines interact with each other. It is shown by self-emission measurement that two colliding plasmas stagnate on a midplane, forming two planar dense regions, and that they interact later in time. Laser Thomson scattering spectra are distorted in the direction of the self-generated magnetic field, indicating asymmetric ion velocity distribution and plasma acceleration. In addition, the spectra perpendicular to the magnetic field show different peak intensity, suggesting an electron current formation. These results are interpreted as magnetic field dissipation, reconnection, and outflow acceleration. Two-directional laser Thomson scattering is, as discussed here, a powerful tool for the investigation of microphysics in the reconnection region.

The feasibility of a newly developed local network system for cardiac rehabilitation (the CR-GNet) in disease management and physical fitness after acute coronary syndrome

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Grant-in-aid from.jpgu Prefecture

Background

The newly developed Cardiac Rehabilitation.jpgu Network (CR-GNet) has been implemented to create a regional alliance network and to provide periodic follow-up examinations to enhance the disease management in patients with cardiovascular disease. The effectiveness of a network like this support system has not yet been evaluated in Japan.

Purpose

We aimed to examine the feasibility of the CR-GNet in disease management, assisting patients in attaining physical fitness and its impact on long-term outcomes after acute coronary syndrome (ACS).

Methods

We enrolled 47 patients with ACS in the CR-GNet between February 2016 and September 2019; of these, 37, 29, and 21 patients underwent follow-up assessments for exercise capacity (peak oxygen uptake) at 3 months, 6 months, and 1 year after discharge, respectively. Major adverse cardiac events (MACE) were defined as the composite of death from cardiac causes, cardiac arrest, myocardial infarction, and rehospitalization due to unstable or progressive angina. MACE were compared with controls who were not registered in the CR-GNet.

Results

The coronary risk factors, except blood pressure, improved at 3 and 6 months, and 1 year after discharge. These risk factors in each patient significantly reduced from 2.9 at admission to 1.6, 1.4, and 1.9 at 3 months, 6 months, and 1 year after discharge (p < 0.05), respectively. Peak oxygen uptake was significantly higher at 3 months, 6 months, and 1 year after discharge to 17.5 ± 4.9 ml/kg/min, 17.9 ± 5.1 ml/kg/min, and 17.5 ± 5.5 ml/kg/min, respectively, than that at discharge (14.7 ± 3.6 ml/kg/min) (p < 0.05). During follow-up, there was no significant difference; MACE did not occur in any patients in the CR-GNet but occurred in controls.

Conclusions

The CR-GNet is a feasible option for long-term management of ACS patients. The prognostic impact of the CR-GNet needs further investigation with a larger sample size and longer follow-up.

Table1 At admission 3 months 6 months 1 year Average number 2.9 1.6* 1.4** 1.9*** † Average number of coronary risk factors for all patients (n = 21) p = 0.004, vs. at admission; **p = 0.001, vs. at admission; ***p = 0.011, vs. at admission; †p = 0.035, vs. at 6 months

Complement profile in microscopic polyangiitis and granulomatosis with polyangiitis: analysis using sera from a nationwide prospective cohort study

OBJECTIVE

The complement cascade, especially the alternative pathway of complement, has been shown in basic research to be associated with anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV). We aimed to elucidate relationships between serum complement components and clinical characteristics in AAV.

METHOD

In a nationwide prospective cohort study (RemIT-JAV-RPGN), we measured the serum levels of C1q, C2, C3, C3b/iC3b, C4, C4b, C5, C5a, C9, factor B, factor D, factor H, factor I, mannose-binding lectin, and properdin in 52 patients with microscopic polyangiitis (MPA) and 39 patients with granulomatosis with polyangiitis (GPA).

RESULTS

The properdin level of MPA and GPA was significantly lower than that of healthy donors. The properdin level was negatively correlated with the Birmingham Vasculitis Activity Score (BVAS) (ρ = -0.2148, p = 0.0409). The factor D level at 6 months was significantly positively correlated with the Vasculitis Damage Index (VDI) at 6, 12, and 24 months (ρ = 0.4207, 0.4132, and 0.3115, respectively). Patients with a higher ratio of C5a to C5 had higher neutrophil percentage and serum immunoglobulin G levels, and significantly lower creatinine levels. Cluster analysis divided the MPA and GPA patients into three subgroups. A principal component (PC) analysis aggregated 15 types of complements into alternative pathway-related PC 1 and complement classical pathway and common pathway-related PC 2.

CONCLUSIONS

The serum levels of properdin and factor D were correlated with the BVAS and the VDI in MPA and GPA, respectively. Our analyses suggested the pathological heterogeneity of MPA and GPA from the aspect of complement components.

Renal iodine123-metaiodobenzylguanidine scintigraphy relates to muscle sympathetic nervous activity in heart failure with reduced ejection fraction

BACKGROUND

Renal denervation is effective for modulating augmented sympathetic nerve activity (SNA) in heart failure with reduced ejection fraction (HFrEF). We have demonstrated that renal iodine¹²³-metaiodobenzylguanidine (¹²³I-MIBG) scintigraphy is associated with muscle sympathetic nerve activity (MSNA) in patients with hypertension. However, it is unclear whether renal ¹²³I-MIBG scintigraphy is useful for assessment of SNA in HFrEF.

METHODS

The study population consisted of 24 HFrEF patients and 11 healthy subjects as controls. Patients with HFrEF underwent ¹²³I-MIBG scintigraphy and hemodynamics using a Swan-Ganz catheter (SGC). HFrEF was defined as echocardiography with left ventricular ejection fraction (LVEF) < 50%. MSNA was measured from the peroneal nerve for direct evaluation of SNA. Renal ¹²³I-MIBG scintigraphy was performed simultaneously with cardiac scintigraphy. The early and delayed kidney-to-mediastinum ratio (K/M), early and delayed heart-to-mediastinum ratio (H/M), and washout rate (WR) were calculated.

RESULTS

LVEFs were 35% ± 11% in patients with HFrEF and 63% ± 10% in the controls (p < 0.01). The WR of cardiac ¹²³I-MIBG showed no relation to MSNA, but was related to stroke volume (r = 0.45, p < 0.05). In contrast, the WR of renal ¹²³I-MIBG scintigraphy (average of both sides) showed a strong correlation with MSNA (BI, r = 0.70, p < 0.01; BF, r = 0.66, p < 0.01); however, no significant correlations were detected between renal ¹²³I-MIBG scintigraphy and SGC results.

CONCLUSIONS

The WR of renal ¹²³I-MIBG scintigraphy may reflect MSNA. Further studies are needed to clarify the relationship between renal ¹²³I-MIBG imaging and renal SNA.

P1444 Occurrence and predictors of right ventricular dysfunction after pericardiocentesis

Background—The changes in cardiac function that occur after pericardiocentesis are unclear.Purpose—This study was performed to assess right ventricular (RV) and left ventricular (LV) function with echocardiography before and after pericardiocentesis.

Method and Results—In total, 19 consecutive patients who underwent pericardiocentesis for more than moderate pericardial effusion were prospectively enrolled from August 2015 to October 2017. Comprehensive transthoracic echocardiography was performed before, immediately after (within 3 hours), and 1 day after pericardiocentesis to investigate the changes in RV and LV function. RV dysfunction is defined as meeting three of the four criteria: a TAPSE of &lt;17 mm, an S’ of &lt;9.5 cm, an FAC of &lt;35%, and an RV free wall longitudinal strain &gt;−20%. The mean age of all patients was 72.6 ± 12.2 years. The changes of echocardiographic parameters related to RV function are shown in Table. After pericardiocentesis, RV inflow and outflow diameters increased and the parameters of RV function significantly decreased. These abnormal values or RV dysfunction remained at 1 day after pericardiocentesis. Conversely, no parameters of LV function parameters changed after pericardiocentesis. Of 19 patients, 13 patients showed RV dysfunction immediately after pericardiocentesis and 6 patients did not. RV free wall longitudinal strain before pericardiocentesis was higher in patients with post-procedural RV dysfunction (−18.9 ± 3.6%) than in those without (−28.4 ± 6.3%). ROC analysis revealed that a RV free wall longitudinal strain cut-off value of −23.0% had a sensitivity of 100% and a specificity of 83.3% for predicting the occurrence of RV dysfunction after pericardiocentesis (AUC = 0.910).

Conclusions—The occurrence of RV dysfunction after pericardiocentesis should be given more attention. Pre-existing RV dysfunction maybe related to the occurrence of RV dysfunction after pericardiocentesis.

Changes in RV function before and after Before Immediately after One day after P−value Basal right ventricular linear dimension (mm) 32.8 ± 5.0 37.1 ± 4.4† 33.6 ± 5.4 0.028 Mid-cavity right ventricular linear dimension (mm) 34.5 ± 4.6 38.8 ± 5.3† 37.0 ± 5.6 0.0504 Proximal right ventricular outflow diameter (mm) 30.2 ± 4.0 33.9 ± 3.5† 31.4 ± 3.9 0.014 TAPSE (mm) 20.0 ± 4.2 13.6 ± 4.3* 14.7 ± 3.9 &lt;0.001 S" (cm/s) 12.6 ± 3.3 8.7 ± 2.4* 9.1 ± 2.4 &lt;0.001 Fractional area change (%) 48.3 ± 5.9 37.8 ± 8.0* 40.0 ± 9.0 &lt;0.001 Right ventricular free wall strain (%) −21.3 ± 6.3 −15.8 ± 6.7* −16.9 ± 5.2 0.036 Tricuspid regurgitation velocity peak (m/s) 2.41 ± 0.29 2.43 ± 0.25 2.34 ± 0.32 0.37

Impact of iterative reconstruction with resolution recovery in myocardial perfusion SPECT: phantom and clinical studies

The corrections of photon attenuation, scatter, and depth-dependent blurring improve image quality in myocardial perfusion single-photon emission computed tomography (SPECT) imaging; however, the combined corrections induce artifacts. Here, we present the single correction method of depth-dependent blurring and its impact for myocardial perfusion distribution in phantom and clinical studies. The phantom and clinical patient images were acquired with two conditions: circular and noncircular orbits of gamma cameras yielded constant and variable depth-dependent blurring, respectively. An iterative reconstruction with the correction method of depth-dependent was used to reconstruct the phantom and clinical patient images. We found that the single correction method improved the robustness of phantom images whether the images contained constant or variable depth-dependent blurring. The myocardial perfusion databases generated from 72 normal patients exhibited uniform perfusion distribution of whole myocardium. In summary, the single correction method of depth-dependent blurring with iterative reconstruction is helpful for myocardial perfusion SPECT.

Initial Experience With Radium-223 Chloride Treatment at the Kanazawa University Hospital

BACKGROUND/AIM

To evaluate our initial experience with radium-223 chloride (Ra-223).

MATERIALS AND METHODS

A total of 26 castration-resistant prostate cancer (CRPC) patients with bone metastases, treated with Ra-223 at our hospital were evaluated. This study aimed to observe adverse events (AEs) and changes in serum markers, and Bone Scan Index (BSI). Additionally, the relationship between these values and OS was investigated.

RESULTS

The observed AEs mainly included fatigue and nausea. Alkaline phosphatase (ALP) and bone-type alkaline phosphatase (BAP) levels decreased following the treatment; however, those of PSA and 1-CTP tended to increase, regardless of Ra-223 administration. Overall survival (OS) was significantly improved in cases with a baseline BSI value of <2 compared with those with a baseline BSI value of ≥2. Moreover, the decrease in BSI after administration of Ra-223 was an independent factor, significantly prolonging OS.

CONCLUSION

ALP and BAP levels and BSI values are suitable evaluation markers during treatment with Ra-223. Also, baseline BSI values and the decrease in BSI following treatment are independent factors predicting OS.

Validation of 2-year 123I-meta-iodobenzylguanidine-based cardiac mortality risk model in chronic heart failure

Aims

The aim of this study was to validate a four-parameter risk model including ¹²³I-meta-iodobenzylguanidine (MIBG) imaging, which was previously developed for predicting cardiac mortality, in a new cohort of patients with chronic heart failure (CHF).

Methods and results

Clinical and outcome data were retrospectively obtained from 546 patients (age 66 ± 14 years) who had undergone ¹²³I-MIBG imaging with a heart-to-mediastinum ratio (HMR). The mean follow-up time was 30 ± 20 months, and the endpoint was cardiac death. The mortality outcome predicted by the model was compared with actual 2-year event rates in pre-specified risk categories of three or four risk groups using Kaplan–Meier survival analysis for cardiac death and receiver-operating characteristic (ROC) analysis. Cardiac death occurred in 137 patients, including 105 (68%) patients due to heart-failure death. With a 2-year mortality risk from the model divided into three categories of low- (<4%), intermediate- (4–12%), and high-risk (>12%), 2-year cardiac mortality was 1.1%, 7.9%, and 54.7%, respectively in the validation population (P < 0.0001). In a quartile analysis, although the predicted numbers of cardiac death was comparable with actual number of cardiac death for low- to intermediate-risk groups with a mortality risk <13.8%, it was underestimated in the high-risk group with a mortality risk ≥13.8%. The ROC analysis showed that the 2-year risk model had better (P < 0.0001) diagnostic ability for predicting heart failure death than left ventricular ejection fraction, natriuretic peptides or HMR alone.

Conclusion

The 2-year risk model was successfully validated particularly in CHF patients at a low to intermediate cardiac mortality risk.

Creation and characterization of normal myocardial perfusion imaging databases using the IQ·SPECT system

BACKGROUND

Image acquisition by short-time single-photon emission-computed tomography (SPECT) has been made feasible by IQ·SPECT. The aim of this study was to generate normal databases (NDBs) of thallium-201 (201Tl) myocardial perfusion imaging for IQ·SPECT, and characterize myocardial perfusion distribution.

METHODS AND RESULTS

We retrospectively enrolled 159 patients with a low likelihood of cardiac diseases from four hospitals in Japan. All patients underwent short-time 201Tl myocardial perfusion IQ·SPECT with or without attenuation and scatter correction (ACSC) in either supine or prone position. The mean myocardial counts were calculated using 17-segment polar maps. Three NDBs were derived from supine and prone images as well as supine images with ACSC. Differences between the supine and prone positions were observed in the uncorrected sex-segregated NDBs in the mid-inferolateral counts (p ≤ 0.016 for males and p ≤ 0.002 for females). Differences between IQ·SPECT and conventional SPECT were also observed in the mid-anterior, inferolateral, and apical lateral counts (p ≤ 0.009 for males and p ≤ 0.003 for females). Apical low counts attributed to myocardial thinning were observed in the apical anterior and apex segments in the supine IQ·SPECT NDB with ACSC.

CONCLUSIONS

There were significant differences between uncorrected supine and prone NDBs, between uncorrected supine NDB and supine NDB with ACSC, and between uncorrected supine NDB and conventional SPECT NDB. Understanding the pattern of normal distribution in IQ-SPECT short-time acquisitions with and without ACSC will be helpful for interpretation of imaging findings in patients with coronary artery disease (CAD) or low likelihood of CAD and the NDBs will aid in quantitative analysis.

Is 123I-metaiodobenzylguanidine heart-to-mediastinum ratio dependent on age? From Japanese Society of Nuclear Medicine normal database

BACKGROUND

Heart-to-mediastinum ratios (HMRs) of 123I-metaiodobenzylguanidine (MIBG) have usually been applied to prognostic evaluations of heart failure and Lewy body disease. However, whether these ratios depend on patient age has not yet been clarified using normal databases.

METHODS

We analyzed 62 patients (average age 57 ± 19 years, male 45%) derived from a normal database of the Japanese Society of Nuclear Medicine working group. The HMR was calculated from early (15 min) and delayed (3-4 h) anterior planar 123I-MIBG images. All HMRs were standardized to medium-energy general purpose (MEGP) collimator equivalent conditions using conversion coefficients for the collimator types. Washout rates (WR) were also calculated, and we analyzed whether early and late HMR, and WR are associated with age.

RESULTS

Before standardization of HMR to MEGP collimator conditions, HMR and age did not significantly correlate. However, late HMR significantly correlated with age after standardization: late HMR = - 0.0071 × age + 3.69 (r2 = 0.078, p = 0.028), indicating that a 14-year increase in age corresponded to a decrease in HMR of 0.1. Whereas the lower limit (2.5% quantile) of late HMR was 2.3 for all patients, it was 2.5 and 2.0 for those aged ≤ 63 and > 63 years, respectively. Early HMR tended to be lower in subjects with the higher age (p = 0.076), whereas WR was not affected by age.

CONCLUSION

While late HMR was slightly decreased in elderly patients, the lower limit of 2.2-2.3 can still be used to determine both early and late HMR.

Ability of the prognostic model of J-ACCESS study to predict cardiac events in a clinical setting: The APPROACH study

BACKGROUND

In patients with coronary artery disease (CAD), one of the risk models available in Japan was a multivariate risk prediction model based on a Japanese multicenter database: the Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT (J-ACCESS). The aim of this study was to clinically validate the accuracy of this risk model.

METHODS

We evaluated the performance of the J-ACCESS model using data derived from the Assessment of the Predicted value of PROgnosis of cArdiaC events in Hokuriku (APPROACH) registry. Variables of age, summed stress score (SSS), left ventricular ejection fraction (LVEF), estimated glomerular filtration rate (eGFR), and diabetes mellitus were included. The major cardiac events were defined as cardiac death, non-fatal myocardial infarction, and heart failure that required hospitalization. The patients were followed up for three years to compare between predicted risk and actual events.

RESULTS

We evaluated 283 patients with suspected or confirmed CAD receiving myocardial perfusion imaging using ^99mTc-tetrofosmin between March 2009 and August 2011. Mean age was 68.9±10.1 years, mean eGFR 67.4±24.3mL/min/1.73m², mean SSS 5.2±7.2, and mean LVEF 65.4±14.0%. Fourteen (4.9%) patients experienced major cardiac events including cardiac death in 4 patients (1.4%), non-fatal myocardial infarction in 1 patient (0.3%), and severe heart failure in 9 patients (3.2%), respectively. While SSS≥8, LVEF<50%, eGFR<45mL/min/1.73m², and event risk≥10% were significant variables in survival analysis, multivariate proportional hazard analysis showed that only LVEF and eGFR were significant. The event rate estimated from the J-ACCESS model was comparable to the actual number of major cardiac events (9 and 6, respectively, p=0.58 by Chi-square test).

CONCLUSIONS

The predictive ability of the J-ACCESS risk model is clinically valid among patients with CAD and could be applicable in clinical practice.

Diagnostic accuracy of an artificial neural network compared with statistical quantitation of myocardial perfusion images: a Japanese multicenter study

PURPOSE

Artificial neural networks (ANN) might help to diagnose coronary artery disease. This study aimed to determine whether the diagnostic accuracy of an ANN-based diagnostic system and conventional quantitation are comparable.

METHODS

The ANN was trained to classify potentially abnormal areas as true or false based on the nuclear cardiology expert interpretation of 1001 gated stress/rest 99mTc-MIBI images at 12 hospitals. The diagnostic accuracy of the ANN was compared with 364 expert interpretations that served as the gold standard of abnormality for the validation study. Conventional summed stress/rest/difference scores (SSS/SRS/SDS) were calculated and compared with receiver operating characteristics (ROC) analysis.

RESULTS

The ANN generated a better area under the ROC curves (AUC) than SSS (0.92 vs. 0.82, p < 0.0001), indicating better identification of stress defects. The ANN also generated a better AUC than SDS (0.90 vs. 0.75, p < 0.0001) for stress-induced ischemia. The AUC for patients with old myocardial infarction based on rest defects was 0.97 (0.91 for SRS, p = 0.0061), and that for patients with and without a history of revascularization based on stress defects was 0.94 and 0.90 (p = 0.0055 and p < 0.0001 vs. SSS, respectively). The SSS/SRS/SDS steeply increased when ANN values (probability of abnormality) were >0.80.

CONCLUSION

The ANN was diagnostically accurate in various clinical settings, including that of patients with previous myocardial infarction and coronary revascularization. The ANN could help to diagnose coronary artery disease.

IQ·SPECT technology and its clinical applications using multicenter normal databases

IQ·SPECT (Siemens Medical Solutions) is a solution for high-sensitivity and short-time acquisition imaging of the heart for a variable angle general purpose gamma camera. It consists of a multi-focal collimator, a cardio-centric orbit and advanced iterative reconstruction, modeling the image formation physics accurately. The multi-focal collimator enables distance-dependent enlargement of the center region while avoiding truncation at the edges. With the specified configuration and a cardio-centric orbit it can obtain a fourfold sensitivity increase for the heart at the center of the scan orbit. Since IQ·SPECT shows characteristic distribution patterns in the myocardium, appropriate acquisition and processing conditions are required, and normal databases are convenient for quantification of both normal and abnormal perfusion images. The use of prone imaging can be a good option when X-ray computed tomography (CT) is not available for attenuation correction. CT-based attenuation correction changes count distribution significantly in the inferior wall and around the apex, hence image interpretation training and additional use of normal databases are recommended. Recent reports regarding its technology, Japanese Society of Nuclear Medicine working group activities, and clinical studies using ²⁰¹Tl and ^99mTc-perfusion tracers in Japan are summarized.

Reducing the small-heart effect in pediatric gated myocardial perfusion single-photon emission computed tomography

BACKGROUND

We compared two reconstruction algorisms and two cardiac functional evaluation software programs in terms of their accuracy for estimating ejection fraction (EF) of small hearts (SH).

METHODS

The study group consisted of 66 pediatric patients. Data were reconstructed using a filtered back projection (FBP) method without the resolution correction (RC) and an iterative method based on an ordered subset expectation maximization (OSEM) algorithm with the RC. EF was evaluated using two software programs of quantitative gated single-photon emission computed tomography (SPECT) (QGS) and cardioREPO. We compared the EF of gated myocardial perfusion SPECT to echocardiographic measurement (Echo).

RESULTS

Forty-eight of 66 patients had an end-systolic volume < 20 mL which was used as the criterion for being included in the SH group, and the SH effect led to an overestimation of EF. While significant differences were observed between Echo (66.9 ± 5.0%) and QGS-FBP without RC (76.9 ± 8.4%, P < .0001), QGS-OSEM with RC (76.6 ± 8.6%, P < .0001), and cardioREPO-FBP without RC (72.1 ± 10.0%, P = .0011), no significant difference was observed between Echo and cardioREPO-OSEM with RC (67.4 ± 6.1%) in SH group.

CONCLUSIONS

In pediatric gated myocardial perfusion SPECT, the SH effect can be significantly reduced when an OSEM algorithm is used with RC in combination with the specific cardioREPO algorithm.

IQ-SPECT for thallium-201 myocardial perfusion imaging: effect of normal databases on quantification

OBJECTIVE

Although IQ-single-photon emission computed tomography (SPECT) provides rapid acquisition and attenuation-corrected images, the unique technology may create characteristic distribution different from the conventional imaging. This study aimed to compare the diagnostic performance of IQ-SPECT using Japanese normal databases (NDBs) with that of the conventional SPECT for thallium-201 (²⁰¹Tl) myocardial perfusion imaging (MPI).

METHODS

A total of 36 patients underwent 1-day ²⁰¹Tl adenosine stress-rest MPI. Images were acquired with IQ-SPECT at approximately one-quarter of the standard time of conventional SPECT. Projection data acquired with the IQ-SPECT system were reconstructed via an ordered subset conjugate gradient minimizer method with or without scatter and attenuation correction (SCAC). Projection data obtained using the conventional SPECT were reconstructed via a filtered back projection method without SCAC. The summed stress score (SSS) was calculated using NDBs created by the Japanese Society of Nuclear Medicine working group, and scores were compared between IQ-SPECT and conventional SPECT using the acquisition condition-matched NDBs. The diagnostic performance of the methods for the detection of coronary artery disease was also compared.

RESULTS

SSSs were 6.6 ± 8.2 for the conventional SPECT, 6.6 ± 9.4 for IQ-SPECT without SCAC, and 6.5 ± 9.7 for IQ-SPECT with SCAC (p = n.s. for each comparison). The SSS showed a strong positive correlation between conventional SPECT and IQ-SPECT (r = 0.921 and p < 0.0001), and the correlation between IQ-SPECT with and without SCAC was also good (r = 0.907 and p < 0.0001). Regarding diagnostic performance, the sensitivity, specificity, and accuracy were 80.8, 78.9, and 79.4%, respectively, for the conventional SPECT; 80.8, 80.3, and 82.0%, respectively, for IQ-SPECT without SCAC; and 88.5, 86.8, and 87.3%, respectively, for IQ-SPECT with SCAC, respectively. The area under the curve obtained via receiver operating characteristic analysis were 0.77, 0.80, and 0.86 for conventional SPECT, IQ-SPECT without SCAC, and IQ-SPECT with SCAC, respectively (p = n.s. for each comparison).

CONCLUSIONS

When appropriate NDBs were used, the diagnostic performance of ²⁰¹Tl IQ-SPECT was comparable with that of the conventional system regardless of different characteristics of myocardial accumulation in the conventional system.

FUT2 non-secretor status is associated with Type 1 diabetes susceptibility in Japanese children

AIM

To examine the contribution of the FUT2 gene and ABO blood type to the development of Type 1 diabetes in Japanese children.

METHODS

We analysed FUT2 variants and ABO genotypes in a total of 531 Japanese children diagnosed with Type 1 diabetes and 448 control subjects. The possible association of FUT2 variants and ABO genotypes with the onset of Type 1 diabetes was statistically examined.

RESULTS

The se2 genotype (c.385A>T) of the FUT2 gene was found to confer susceptibility to Type 1A diabetes in a recessive effects model [odds ratio for se2/se2, 1.68 (95% CI 1.20-2.35); corrected P value = 0.0075].

CONCLUSIONS

The FUT2 gene contributed to the development of Type 1 diabetes in the present cohort of Japanese children.

Significant correlation between renal 123I-metaiodobenzylguanidine scintigraphy and muscle sympathetic nerve activity in patients with primary hypertension

BACKGROUND

Iodine-123 metaiodobenzylguanidine (123I-MIBG) scintigraphy is used as a noninvasive imaging method for assessing cardiac sympathetic nerve activity. We tested the hypothesis that renal 123I-MIBG imaging is correlated with muscle sympathetic nerve activity (MSNA) in patients with primary hypertension.

METHODS

Thirty-one consecutive patients with primary hypertension were included. Multiunit MSNA was recorded from the peroneal nerve to evaluate direct efferent sympathetic nerve activity. Planar renal and cardiac 123I-MIBG images were acquired. Early and delayed kidney-to-mediastinum ratio (K/M), early and delayed heart-to-mediastinum ratio (H/M), and washout rates (WR) were calculated.

RESULTS

In 27 of 31 patients, blood pressure was controlled on antihypertensive medication. Mean systolic and diastolic blood pressures were 118 ± 18 and 67 ± 15 mmHg, respectively. Although early and late K/M and H/M were not significantly correlated with MSNA, both cardiac and average renal WR were significantly correlated with MSNA (r = 0.45, P = .0035 and r = 0.68, P < .001, respectively). Right and left renal WR were similarly correlated with MSNA. Renal WR was significantly higher than cardiac WR (43.2% vs 25.8%, P < .001) in these patients with hypertension.

CONCLUSIONS

Renal 123I-MIBG WR was significantly associated with multiunit MSNA. Renal 123I-MIBG imaging offers a noninvasive clinical methodology for assessing renal sympathetic nerve function.

Comparison of phase dyssynchrony analysis using gated myocardial perfusion imaging with four software programs: Based on the Japanese Society of Nuclear Medicine working group normal database

PURPOSE

Left ventricular (LV) phase dyssynchrony parameters based on gated myocardial perfusion imaging varied among software programs. The aim of this study was to determine normal ranges and factors affecting phase parameters.

METHODS

Normal databases were derived from the Japanese Society of Nuclear Medicine working group (n = 69). The programs were Emory Cardiac Toolbox with SyncTool (ECTb), Quantitative Gated SPECT (QGS), Heart Function View (HFV), and cardioREPO (cREPO); parameters of phase standard deviation (PSD), 95% bandwidth, and entropy were compared with parameters with ECTb as a reference.

RESULTS

PSD (degree) was 5.3 ± 3.3 for QGS (P < .0001), 5.4 ± 2.5 for HFV (P < .0001), and 10.3 ± 3.2 for cREPO (P = n. s.) compared with 11.5 ± 5.5 for ECTb. Phase bandwidth with three programs differed significantly from ECTb. Gender differences were significant for all programs, indicating larger variation in males. After adjustment of LV volumes between genders, the difference disappeared except for QGS. The phase parameters showed wider variations in patients with the lower ejection fraction (EF) and larger LV volumes, depending on software types.

CONCLUSION

Based on normal ranges of phase dyssynchrony parameters in four software programs, dependency on genders, LV volume, and EF should be considered, indicating the need for careful comparison among different software programs.

Comparison of diagnostic performance of four software packages for phase dyssynchrony analysis in gated myocardial perfusion SPECT

Background

Phase analysis of gated myocardial perfusion single-photon emission computed tomography (SPECT) for assessment of left ventricular (LV) dyssynchrony was investigated using the following dedicated software packages: Corridor4DM (4DM), cardioREPO (cREPO), Emory Cardiac Toolbox (ECTb), and quantitative gated SPECT (QGS). The purpose of this study was to evaluate the normal values of 95% histogram bandwidth, phase standard deviation (SD), and entropy and to compare the diagnostic performance of the four software packages. A total of 122 patients with normal myocardial perfusion and cardiac function (58.9 ± 12.3 years, 60 women, ejection fraction (EF) 74.3 ± 5.7%, and end-diastolic volume (EDV) 83.5 ± 3.6 mL) and 34 patients with suspected LV dyssynchrony (64.1 ± 12.2 years, 9 women, EF 52.0 ± 18.0%, and EDV 145.0 ± 6.8 mL) who underwent Tc-99m methoxy-isobutyl-isonitrile/tetrofosmin gated SPECT were retrospectively evaluated. Dyssynchrony indices of the 95% histogram bandwidth, phase SD, and entropy were computed with the four software programs. Diagnostic performance of LV phase dyssynchrony assessments was determined by receiver operator characteristic (ROC) analysis. The area under the ROC curve (AUC) was used to compare the software programs. The optimal cutoff point was determined by ROC curve based on the Youden index.

Results

The average of normal bandwidth significantly differed among the four software programs except in the comparison of 4DM and ECTb. Moreover, the normal phase SD significantly differed among the four software programs except in the comparison of cREPO and ECTb. The software programs showed high correlation levels for bandwidth, phase SD, and entropy (r ≥ 0.73, p < 0.001). ROC AUCs of bandwidth, phase SD, and entropy were ≥0.850, ≥0.858, and ≥0.900, respectively. Moreover, the ROC AUCs of bandwidth, phase SD, and entropy did not significantly differ among the four software programs. Optimal cutoff points for phase parameters were 24°–42° for bandwidth, 8.6°–15.3° for phase SD, and 31–48% for entropy.

Conclusions

Although the optimal cutoff value for determining LV phase dyssynchrony by ROC analysis varied depending on the use of the different software programs, all software programs can be used reliably for phase dyssynchrony analysis.

Variants associated with autoimmune Type 1 diabetes in Japanese children: implications for age-specific effects of cis-regulatory haplotypes at 17q12-q21

AIMS

The aim of this study was to clarify the significance of previously reported susceptibility variants in the development of autoimmune Type 1 diabetes in non-white children. Tested variants included rs2290400, which has been linked to Type 1 diabetes only in one study on white people. Haplotypes at 17q12-q21 encompassing rs2290400 are known to determine the susceptibility of early-onset asthma by affecting the expression of flanking genes.

METHODS

We genotyped 63 variants in 428 Japanese people with childhood-onset autoimmune Type 1 diabetes and 457 individuals without diabetes. Possible association between variants and age at diabetes onset was examined using age-specific quantitative trait locus analysis and ordered-subset regression analysis.

RESULTS

Ten variants, including rs2290400 in GSDMB, were more frequent among the people with Type 1 diabetes than those without diabetes. Of these, rs689 in INS and rs231775 in CTLA4 yielded particularly high odds ratios of 5.58 (corrected P value 0.001; 95% CI 2.15-14.47) and 1.64 (corrected P value 5.3 × 10^-5 ; 95% CI 1.34-2.01), respectively. Age-specific effects on diabetes susceptibility were suggested for rs2290400; heterozygosity of the risk alleles was associated with relatively early onset of diabetes, and the allele was linked to the phenotype exclusively in the subgroup of age at onset ≤ 5.0 years.

CONCLUSIONS

The results indicate that rs2290400 in GSDMB and polymorphisms in INS and CTLA4 are associated with the risk of Type 1 diabetes in Japanese children. Importantly, cis-regulatory haplotypes at 17q12-q21 encompassing rs2290400 probably determine the risk of autoimmune Type 1 diabetes predominantly in early childhood.

Characteristics of histologically confirmed endometriosis in cynomolgus monkeys

STUDY QUESTION

What are the characteristics of spontaneous endometriosis in cynomolgus monkeys?

SUMMARY ANSWER

Spontaneous endometriosis in cynomolgus monkeys exhibited similar characteristics to the human disease.

WHAT IS KNOWN ALREADY

One previous report described the prevalence and the basic histopathology of spontaneous endometriosis in cynomolgus monkeys.

STUDY DESIGN, SIZE, DURATION

Endometriotic lesions that had been histologically confirmed in 8 female cynomolgus monkeys between 5 and 21 years old were subjected to study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The monkeys died of, or were sacrificed because of, sickness consequent on endometriosis. Specimens were evaluated histopathologically with haematoxylin and eosin staining, iron staining and immunohistochemistry (CD10, CD31, α-SMA and PGP9.5), and by observing them under a microscope.

MAIN RESULTS AND THE ROLE OF CHANCE

Endometriotic and stromal cells (CD10-positive) with haemorrhage and inflammation were observed. Smooth muscle metaplasia and nerve fibres were also noted in the endometriotic lesions. Endometriotic lesions in lymph nodes were incidentally found.

LIMITATIONS AND REASONS FOR CAUTION

Since laparoscopic analysis for monitoring the disease state was not set as a parameter of the current study, time course changes (progression) of the disease were not assessed.

WIDER IMPLICATIONS OF THE FINDINGS

Further investigation of spontaneous endometriosis in cynomolgus monkeys may contribute to better understanding of the disease pathobiology.

STUDY FUNDING/COMPETING INTEREST(S)

No external funds were used for this study. A.N.K., S.M., S.H., T.I., O.K., A.K. and M.S. are full-time employees of Chugai Pharmaceutical Co., Ltd. R.K. received lecture fees from Chugai Pharmaceutical Co., Ltd., unrelated to the submitted work. S.N., S. O., L.Y., K.Y. and T.S. have nothing to declare.

TRIAL REGISTRATION NUMBER

N/A.

Upper-normal waist circumference is a risk marker for metabolic syndrome in normal-weight subjects

BACKGROUND AND AIMS

To elucidate implication of upper-normal waist circumference (WC), we examined whether the normal range of WC still represents a risk of metabolic syndrome (MetS) or non-adipose MetS components among normal-weight subjects.

METHODS AND RESULTS

A total of 173,510 persons (100,386 men and 73,124 women) with normal WC (<90/80 cm in men/women) and body mass index (BMI) of 18.5-24.9 were included. Subjects were categorized as having low, moderate, and upper-normal WC for those with WC < 80, 80-84, and 85-89 cm in men and <70, 70-74, and 75-79 cm in women, respectively. The prevalence of all the non-adipose MetS components (e.g. prediabetes and borderline dyslipidemia) was significantly higher in subjects with upper-normal WC on comparison with those with low WC. Overall, the prevalence of MetS (having three or more of four non-adipose MetS components) gradually increased with increasing WC (12%, 21%, and 27% in men and 11%, 14%, and 19% in women for low, moderate, and upper-normal WC, respectively). Moreover, the risk of having a greater number of MetS components increased in subjects with upper-normal WC compared with those with low WC (odds ratios for the number of one, two, three, and four MetS components: 1.29, 1.81, 2.53, and 2.47 in men and 1.16, 1.55, 1.49, and 2.20 in women, respectively).

CONCLUSION

Upper-normal WC represents a risk for acquiring a greater number of MetS components and the early stage of MetS components (prediabetes and borderline dyslipidemia), after adjusting for BMI, in a large general population with normal WC and BMI.

Creation of mortality risk charts using 123I meta-iodobenzylguanidine heart-to-mediastinum ratio in patients with heart failure: 2- and 5-year risk models

Aims

¹²³I meta-iodobenzylguanidine (MIBG) imaging has been extensively used for prognostication in patients with chronic heart failure (CHF). The purpose of this study was to create mortality risk charts for short-term (2 years) and long-term (5 years) prediction of cardiac mortality.

Methods and results

Using a pooled database of 1322 CHF patients, multivariate analysis, including ¹²³I-MIBG late heart-to-mediastinum ratio (HMR), left ventricular ejection fraction (LVEF), and clinical factors, was performed to determine optimal variables for the prediction of 2- and 5-year mortality risk using subsets of the patients (n = 1280 and 933, respectively). Multivariate logistic regression analysis was performed to create risk charts. Cardiac mortality was 10 and 22% for the sub-population of 2- and 5-year analyses. A four-parameter multivariate logistic regression model including age, New York Heart Association (NYHA) functional class, LVEF, and HMR was used. Annualized mortality rate was <1% in patients with NYHA Class I–II and HMR ≥ 2.0, irrespective of age and LVEF. In patients with NYHA Class III–IV, mortality rate was 4–6 times higher for HMR < 1.40 compared with HMR ≥ 2.0 in all LVEF classes. Among the subset of patients with b-type natriuretic peptide (BNP) results (n = 491 and 359 for 2- and 5-year models, respectively), the 5-year model showed incremental value of HMR in addition to BNP.

Conclusion

Both 2- and 5-year risk prediction models with ¹²³I-MIBG HMR can be used to identify low-risk as well as high-risk patients, which can be effective for further risk stratification of CHF patients even when BNP is available.

Prognostic Value of Cardiac Sympathetic Nerve Imaging Using Long-Term Follow-up Data - Ischemic vs. Non-Ischemic Heart Failure Etiology

BACKGROUND

Although there are several known prognostic determinants in heart failure (HF), individual risk profiles can vary, in particular between ischemic and non-ischemic HF background. This study investigated the difference in prognostic efficacy of cardiac (123)I-meta-iodobenzylguanidine (MIBG) imaging between the 2 etiologies.

METHODS AND RESULTS

All 1,322 patients with HF were enrolled and followed up at most after 10 years. The HF patients were divided into 2 groups: an ischemic group (n=362) and non-ischemic group (n=960), and Cox proportional hazards model was used for data analysis. During 10 years of follow-up, 296 (22.4%) of 1,322 patients died; the mortality rates were 21.8% and 22.6% for the ischemic and non-ischemic groups, respectively. The ischemic group had greater prevalence of sudden death and lethal acute myocardial infarction, and the non-ischemic group had a higher rate of pump failure death. On multivariate Cox proportional hazards analysis using categorized variables, in the ischemic group, delayed heart-to-mediastinum ratio (HMR; P<0.0001), age (P=0.0002) and LVEF (P=0.03) were the independent significant predictors of lethal events. In the non-ischemic group, delayed HMR (P<0.0001), NYHA class (P<0.0001) and age (P<0.0001) were significant determinants of lethal outcome.

CONCLUSIONS

Cardiac MIBG imaging has nearly identical prognostic value in both ischemic and non-ischemic HF, independent of cause of cardiac death.

[The Optimal Reconstruction Parameters by Scatter and Attenuation Corrections Using Multi-focus Collimator System in Thallium-201 Myocardial Perfusion SPECT Study]

The aim of this study was to reveal the optimal reconstruction parameters of ordered subset conjugates gradient minimizer (OSCGM) by no correction (NC), attenuation correction (AC), and AC+scatter correction (ACSC) using IQ-single photon emission computed tomography (SPECT) system in thallium-201 myocardial perfusion SPECT. Myocardial phantom acquired two patterns, with or without defect. Myocardial images were performed 5-point scale visual score and quantitative evaluations using contrast, uptake, and uniformity about the subset and update (subset×iteration) of OSCGM and the full width at half maximum (FWHM) of Gaussian filter by three corrections. We decided on optimal reconstruction parameters of OSCGM by three corrections. The number of subsets to create suitable images were 3 or 5 for NC and AC, 2 or 3 for ACSC. The updates to create suitable images were 30 or 40 for NC, 40 or 60 for AC, and 30 for ACSC. Furthermore, the FWHM of Gaussian filters were 9.6 mm or 12 mm for NC and ACSC, 7.2 mm or 9.6 mm for AC. In conclusion, the following optimal reconstruction parameters of OSCGM were decided; NC: subset 5, iteration 8 and FWHM 9.6 mm, AC: subset 5, iteration 8 and FWHM 7.2 mm, ACSC: subset 3, iteration 10 and FWHM 9.6 mm.

Mode-selective optical packet switching in mode-division multiplexing networks

A novel mode-selective optical packet switching, based on mode-multiplexers/demultiplexers and multi-port optical micro-electro-mechanical systems (MEMS) switches, has been proposed and experimentally demonstrated. The experimental demonstration was performed using the LP(01), LP(11a) and LP(11b) modes of a 30-km long mode-division multiplexed few-mode fiber link, utilizing 40 Gb/s, 16-QAM signals.

Development and validation of a direct-comparison method for cardiac (123)I-metaiodobenzylguanidine washout rates derived from late 3-hour and 4-hour imaging

PURPOSE

The washout rate (WR) has been used in (123)I-metaiodobenzylguanidine (MIBG) imaging to evaluate cardiac sympathetic innervation. However, WR varies depending on the time between the early and late MIBG scans. Late scans are performed at either 3 or 4 hours after injection of MIBG. The aim of this study was to directly compare the WR at 3 hours (WR3h) with the WR at 4 hours (WR4h).

METHODS

We hypothesized that the cardiac count would reduce linearly between the 3-hour and 4-hour scans. A linear regression model for cardiac counts at two time-points was generated. We enrolled a total of 96 patients who underwent planar (123)I-MIBG scintigraphy early (15 min) and during the late phase at both 3 and 4 hours. Patients were randomly divided into two groups: a model-creation group (group 1) and a clinical validation group (group 2). Cardiac counts at 15 minutes (countearly), 3 hours (count3h) and 4 hours (count4h) were measured. Cardiac count4h was mathematically estimated using the linear regression model from countearly and count3h.

RESULTS

In group 1, the actual cardiac count4h/countearly was highly significantly correlated with count3h/countearly (r = 0.979). In group 2, the average estimated count4h was 92.8 ± 31.9, and there was no significant difference between this value and the actual count4h (91.9 ± 31.9). Bland-Altman analysis revealed a small bias of -0.9 with 95 % limits of agreement of -6.2 and +4.3. WR4h calculated using the estimated cardiac count4h was comparable to the actual WR4h (24.3 ± 9.6 % vs. 25.1 ± 9.7 %, p = ns). Bland-Altman analysis and the intraclass correlation coefficient showed that there was excellent agreement between the estimated and actual WR4h.

CONCLUSION

The linear regression model that we used accurately estimated cardiac count4h using countearly and count3h. Moreover, WR4h that was mathematically calculated using the estimated count4h was comparable to the actual WR4h.

Diagnostic Performance of Artificial Neural Network for Detecting Ischemia in Myocardial Perfusion Imaging

BACKGROUND

The purpose of this study was to apply an artificial neural network (ANN) in patients with coronary artery disease (CAD) and to characterize its diagnostic ability compared with conventional visual and quantitative methods in myocardial perfusion imaging (MPI).

METHODS AND RESULTS

A total of 106 patients with CAD were studied with MPI, including multiple vessel disease (49%), history of myocardial infarction (27%) and coronary intervention (30%). The ANN detected abnormal areas with a probability of stress defect and ischemia. The consensus diagnosis based on expert interpretation and coronary stenosis was used as the gold standard. The left ventricular ANN value was higher in the stress-defect group than in the no-defect group (0.92±0.11 vs. 0.25±0.32, P<0.0001) and higher in the ischemia group than in the no-ischemia group (0.70±0.40 vs. 0.004±0.032, P<0.0001). Receiver-operating characteristics curve analysis showed comparable diagnostic accuracy between ANN and the scoring methods (0.971 vs. 0.980 for stress defect, and 0.882 vs. 0.937 for ischemia, both P=NS). The relationship between the ANN and defect scores was non-linear, with the ANN rapidly increased in ranges of summed stress score of 2-7 and summed defect score of 2-4.

CONCLUSIONS

Although the diagnostic ability of ANN was similar to that of conventional scoring methods, the ANN could provide a different viewpoint for judging abnormality, and thus is a promising method for evaluating abnormality in MPI.

Nuclear myocardial perfusion imaging using thallium-201 with a novel multifocal collimator SPECT/CT: IQ-SPECT versus conventional protocols in normal subjects

OBJECTIVE

A novel multifocal collimator, IQ-SPECT (Siemens) consists of SMARTZOOM, cardio-centric and 3D iterative SPECT reconstruction and makes it possible to perform MPI scans in a short time. The aims are to delineate the normal uptake in thallium-201 ((201)Tl) SPECT in each acquisition method and to compare the distribution between new and conventional protocol, especially in patients with normal imaging.

METHODS

Forty patients (eight women, mean age of 75 years) who underwent myocardial perfusion imaging were included in the study. All patients underwent one-day protocol perfusion scan after an adenosine-stress test and at rest after administering (201)Tl and showed normal results. Acquisition was performed on a Symbia T6 equipped with a conventional dual-headed gamma camera system (Siemens ECAM) and with a multifocal SMARTZOOM collimator. Imaging was performed with a conventional system followed by IQ-SPECT/computed tomography (CT). Reconstruction was performed with or without X-ray CT-derived attenuation correction (AC). Two nuclear physicians blinded to clinical information interpreted all myocardial perfusion images. A semi-quantitative myocardial perfusion was analyzed by a 17-segment model with a 5-point visual scoring. The uptake of each segment was measured and left ventricular functions were analyzed by QPS software.

RESULTS

IQ-SPECT provided good or excellent image quality. The quality of IQ-SPECT images without AC was similar to those of conventional LEHR study. Mid-inferior defect score (0.3 ± 0.5) in the conventional LEHR study was increased significantly in IQ-SPECT with AC (0 ± 0). IQ-SPECT with AC improved the mid-inferior decreased perfusion shown in conventional images. The apical tracer count in IQ-SPECT with AC was decreased compared to that in LEHR (0.1 ± 0.3 vs. 0.5 ± 0.7, p < 0.05). The left ventricular ejection fraction from IQ-SPECT was significantly higher than that from the LEHR collimator (p = 0.0009).

CONCLUSION

The images of IQ-SPECT acquired in a short time are equivalent to that of conventional LEHR. The results indicated that the IQ-SPECT system with AC is capable of correcting inferior artifacts with high image quality.

Performance of the Japanese glomerular filtration rate equation based on standardized serum cystatin C in potential kidney donors

BACKGROUND

It was reported that the glomerula filtration rate (GFR) equation based on serum creatinine underestimated the GFR in potential kidney donors. Recently, the Japanese GFR equation based on standardized serum cystatin C was reported. Therefore, we assessed the performance of the equation in potential kidney donors.

METHODS

Forty-five potential kidney donors from 2 hospitals were included. GFR was measured (mGFR) using inulin renal clearance. Serum creatinine was measured using the enzymatic method. Serum cystatin C was measured using a nephelometric immunoassay (Siemens) and calibrated to the standardized value traceable to ERM-DA471/IFCC using an equation reported previously. The estimated GFR (eGFR) was calculated using the Japanese GFR equation based on serum creatinine (eGFRcreat) and the Japanese GFR equation based on serum cystatin C (eGFRcys). Bias (mGFR - eGFR) and accuracy (P30) of the equations were evaluated.

RESULTS

Inulin clearance, eGFRcreat, and eGFRcys were 91.0 ± 18.2, 78.5 ± 18.8, and 93.3 ± 16.3 mL/min/1.73 m(2), respectively. Bias of eGFRcreat was 12.4 ± 15.8 mL/min/1.73 m(2) and significantly different from zero, indicating underestimation of GFR. Bias of eGFRcys was -2.3 ± 16.3 mL/min/1.73 m(2) and was not significantly different from zero, suggesting better performance. But, the precision (standard deviation [SD] of bias) and accuracy (P30: Percentage of participants with eGFR within 30% of mGFR) of eGFRcys were not better compared with eGFRcreat. Accuracies (P30) of eGFRcreat and eGFRcys were 87% (95% confidence interval [CI], 74-94) and 82% (95% CI, 69-91), respectively.

CONCLUSION

Bias of eGFRcys was better compared with eGFRcreat. But, the precision (SD of bias) and accuracy of eGFRcys were not superior compared with eGFRcreat in potential kidney donors.

Multicenter cross-calibration of I-123 metaiodobenzylguanidine heart-to-mediastinum ratios to overcome camera-collimator variations

BACKGROUND

The heart-to-mediastinum ratio (HMR) of (123)I-metaiodobenzylguanidine (MIBG) showed variations among institutions and needs to be standardized among various scinticamera-collimator combinations.

METHODS

A total of 225 phantom experiments were performed in 84 institutions to calculate cross-calibration coefficients of HMR. Based on phantom studies, a conversion coefficient for each camera-collimator system was created, including low-energy (LE, n = 125) and a medium-energy (ME, n = 100) collimators. An average conversion coefficient from the most common ME group was used to calculate the standard HMR. In clinical MIBG studies (n = 52) from three institutions, HMRs were standardized from both LE- and ME-type collimators and classified into risk groups of <1.60, 1.60-2.19, and ≥2.20.

RESULTS

The average conversion coefficients from the individual camera-collimator condition to the mathematically calculated reference HMR ranged from 0.55 to 0.75 for LE groups and from 0.83 to 0.95 for ME groups. The conversion coefficient of 0.88 was used to unify HMRs from all acquisition conditions. Using the standardized HMR, clinical studies (n = 52) showed good agreement between LE and ME types regarding three risk groups (κ = 0.83, P < .0001, complete agreement in 90%, 42% of the patients reclassified into the same risk group).

CONCLUSION

By using the reference HMR and conversion coefficients for the system, HMRs with various conditions can be converted to the standard HMRs in a range of normal to low HMRs.