Cross calibration of 123I-meta-iodobenzylguanidine heart-to-mediastinum ratio with D-SPECT planogram and Anger camera
Ann Nucl Med
Cross calibration of 123I-meta-iodobenzylguanidine heart-to- mediastinum ratio with D-SPECT planogram and Anger camera
Kenichi Nakajima 0 1 2 3 4 5
Koichi Okuda 0 1 2 3 4 5
Kunihiko Yokoyama 0 1 2 3 4 5
Tatsuya Yoneyama 0 1 2 3 4 5
Shiro Tsuji 0 1 2 3 4 5
Hiroyuki Oda 0 1 2 3 4 5
Mitsuhiro Yoshita 0 1 2 3 4 5
Koji Kubota 0 1 2 3 4 5
0 PET Imaging Center, Public Central Hospital of Matto Ishikawa , Hakusan , Japan
1 Department of Nuclear Medicine, Kanazawa University , 13-1 Takara-machi, Kanazawa 920-8641 , Japan
2 & Kenichi Nakajima
3 Department of Neurology, Hokuriku National Hospital , Nanto , Japan
4 Department of Cardiology, Public Central Hospital of Matto Ishikawa , Hakusan , Japan
5 Department of Physics, Kanazawa Medical University , Uchinada, Kahoku , Japan
Background Cardiac 123I-meta-iodobenzylguanidine (MIBG) uptake is quantified using the heart-to-mediastinum ratio (HMR) with an Anger camera. The relationship between HMR determined using D-SPECT with a cadmium-zinctelluride detector and an Anger camera is not fully understood. Therefore, the present study aimed to define this relationship using images derived from a phantom and from patients. Methods Cross-calibration phantom studies using an Anger camera with a low-energy high-resolution (LEHR) collimator and D-SPECT, and clinical 123I-MIBG studies proceeded in 40 consecutive patients (80 studies). In the phantom study, a conversion coefficient (CC) was defined based on phantom experiments and applied to the Anger camera and the D-SPECT detector. The HMR was calculated using anterior images with the Anger camera and anterior planograms with D-SPECT. First, the HMR from D-SPECT was cross-calibrated to the Anger camera, and then, the HMR from both cameras were converted to the medium-energy general-purpose collimator condition (CC 0.88; ME88 condition). The relationship between HMR and corrected and uncorrected methods was examined. A 123I-MIBG washout rate was calculated using both methods with and without background subtraction. Results Based on the phantom experiments, the CC of the Anger camera with an LEHR collimator and of D-SPECT using an anterior planogram was 0.55 and 0.63, respectively. The original HMR from the Anger camera and D-SPECT was 1.76 ± 0.42 and 1.86 ± 0.55, respectively (p \ 0.0001). After D-SPECT HMR was converted to the Anger camera condition, the corrected D-SPECT HMR became comparable to the values under the Anger camera condition (1.75 ± 0.48, p = n. s.). When the HMR measured using the two cameras were converted under the ME88 condition, the average standardized HMR from the Anger camera and D-SPECT became comparable (2.21 ± 0.65 vs. 2.20 ± 0.75, p = n. s.). After standardization to the ME88 condition, a systematic difference in the linear regression lines disappeared, and the HMR from both the Anger (StdHMRAnger) and D-SPECT (StdHMRDSPECT) became comparable. Additional correction using a regression line further improved the relationship between both HMR [StdHMRDSPECT = 0.09 ? 0.98 9 StdHMRAnger (R2 = 0.91)]. The washout rate closely correlated with and without background correction between both methods (R2 = 0.83 and 0.65, respectively). Conclusion The phantom-based conversion method is applicable to D-SPECT and enables the common application of HMR irrespective of D-SPECT and the Anger camera.
Heart-to-mediastinum ratio; Standardization; Sympathetic imaging coefficient; Quantitation; Conversion
CC Conversion coefficient
HF Heart failure
HMR Heart-to-mediastinum ratio
LE Low energy
ME Medium energy
ME88 Medium-energy collimator condition with a
conversion coefficient of 0.88
ROI Region of interest
Several multicenter studies and meta-analysis in Europe,
the USA and Japan have indicated the value of sympathetic
innervation imaging using 123I-meta-iodobenzylguanidine
(MIBG) for patients with heart failure (HF) [
Clinical Practice Guidelines of Nuclear Cardiology
published by the Japanese Circulation Society included this
procedure based on the considerable accumulation of
clinical experience with 123I-MIBG in Japan [
European Association of Nuclear Medicine (EANM)
Cardiovascular Committee and the European Council of
Nuclear Cardiology have proposed MIBG protocols ,
and the American Society of Nuclear Cardiology (ASNC)
imaging guidelines also summarize the application of
123I-MIBG and its methodology [
]. In addition to
cardiology, 123I-MIBG has been used since the late 1990s with
increasing frequency in patients with Parkinson’s disease
and dementia with Lewy bodies, in whom cardiac
123I-MIBG uptake characteristically decreases due to
neural degeneration [
]. Thus, 123I-MIBG findings are
considered as a biomarker of Lewy-body disease.
Although reproducibility of the heart-to-mediastinum
ratio (HMR) is generally believed to be good [
], a major
factor affecting HMR is differences among camera
collimators at various hospitals [
]. For example, average
normal values of late HMR are 2.5 with low-energy (LE)
collimators and 3.0 for medium-energy (ME) collimators
]. In fact, collimator designs are further divided into at
least 6–7 collimator groups [
], and these differences are
supposed to be mainly caused by different degrees of septal
penetration and scatter in collimators, and the precise
specifications of the size and length of holes and septal
thickness are variable among vendors. We, therefore,
developed a phantom-based correction method to
crosscalibrate HMR among all Anger camera collimator systems
]. Several phantom experiments have shown that even
collimators of the same type, for example, low-energy high
resolution (LEHR), have different specifications depending
on the designs of vendors [
]. D-SPECT (Spectrum
Dynamics, Israel; Biosensors Japan, Tokyo, Japan) has a
cadmium–zinc–telluride (CZT) detector that enables high
resolution and high sensitivity in myocardial perfusion
]. However, tomographic imaging is the
standard output, and planar images commonly used with Anger
cameras are not directly used. Differences between the
Anger and D-SPECT cameras were investigated in the
ADRECARD study, in which virtual anterior planograms
were created with D-SPECT, and the HMR between the
two methods correlated well [
The present study aimed to create a method of
integrating HMR derived from D-SPECT planogram and
Anger cameras using the same phantom-based conversion
method to generate comparable quantitative parameters in
Phantom design and cross calibration of HMR
The structure of the calibration phantom is described
]. Briefly, the phantom was designed for
planar imaging, and two reference HMR values can be
obtained from one phantom using anterior and posterior
sides (Hokuriku Yuuki, Co. Ltd., Kanazawa, Japan). Since
the phantom has two compartments, one for 123I-MIBG and
the other for water, the radionuclide concentration does not
require adjustment, and HMR can be reproducibly
calculated using dedicated software. The reference HMR values
obtained from the anterior and posterior sides of the
phantom were 2.6 and 3.5, respectively. The count decay in
the acrylic and water compartment was calculated for
thickness using an attenuation coefficient of 0.147/cm
A linear regression line that passes through a coordinate
(1, 1) for the measured versus the reference HMR can be
calculated, because two data points are obtained from the
anterior and posterior sides. The slope of this regression
line is defined as a conversion coefficient (CC) to the
reference value, and it is unique for an institutional specific
combination of scinticamera-collimator systems and
Planograms generated by D-SPECT
The standard D-SPECT output comprised tomographic
reconstructed images. Therefore, a planogram equivalent to
a planar anterior image was created based on all
elementary two-dimensional images that shared the same angle
onto one large field of view in a virtual plane as described
]. A series of two-dimensional images equivalent to
those of SPECT with the Anger camera were obtained for
every angular position. The phantom structure was
designed for planar images, which render
three-dimensional reconstruction meaningless. Therefore, we used only
anterior planograms and repeated the acquisition on the
reverse side of the phantom.
Experiments with the calibration phantom proceeded for
the Anger camera (Siemens Healthcare, Tokyo, Japan)
with an LEHR collimator, and planar images were acquired
from both sides of the phantom. Diluted 123I-MIBG
(111 MBq) was poured into the phantom and images were
acquired for 5 min each. A 15% energy window was set at
159 keV. Data were similarly acquired from both sides of
the phantom for D-SPECT. The phantom was positioned
horizontally on the backrest of an SPECT chair similar to
how patients are positioned. A 3-cm acrylic plate filled
with water was placed over the phantom when imaging was
performed to simulate human body attenuation and scatter.
A 15% asymmetric energy window was set at 159 keV
(145–169 keV) for D-SPECT. Figure 1 shows typical
We retrospectively selected 40 consecutive outpatients
(average age, 73 ± 10 years; male, 50%) referred for
123IFig. 1 Phantom images
acquired using Anger camera
(a) and D-SPECT (b). Regions
of interest are drawn on heart
MIBG assessment between July 2016 and February 2017.
The indications for 123I-MIBG assessment were determined
by internal medicine physicians, and their aims for the
study were to diagnose Parkinson’s disease and dementia
with Lewy bodies for neurology, and to evaluate the
diagnosis and prognosis of HF. The diagnosis of
neurological diseases was made in 24 patients. Among the
patients with HF, the average left ventricular ejection
fraction ranged 20–70%.
We used data acquired from all enrolled patients, since
our aim was to develop an optimal methodology. The
Ethics Committee at the Public Central Hospital of Matto
Ishikawa approved this research protocol. Written
informed consent from individual patients was waived,
because the MIBG studies comprised part of regular
clinical practice without additional imaging.
Early and late images were acquired at 15 min and 3 h
after an intravenous injection of 111 MBq of 123I-MIBG
(MyoMIBG; FUJIFILM RI Pharma, Tokyo, Japan) using
an Anger camera. The anterior images were obtained for
5 min each with a 256 9 256 matrix. Just after Anger
camera images, D-SPECT images were acquired for
10 min. An anterior-view equivalent planograms were
generated, and the HMR was then calculated. Tomographic
imaging was a standard clinical procedure used for
evaluating segmental defect caused by ischemia and extensive
decrease in Lewy-body disease, but it was not used in the
Regions of interest and HMR
Phantom analysis We set regions of interest (ROI) on the
heart and mediastinum of the phantom. The heart ROI was
set as a circle on the heart, and the mediastinal ROI was set
as a rectangle on the upper mediastinum with the Anger
camera. The location was predefined for the phantom in all
phantom experiments using the dedicated analytical
software. Since the vertical image size was limited to 160 mm
with D-SPECT, a similar ROI was manually set on the
heart and mediastinum. The mediastinal ROI was set on the
mid-mediastinum as high as possible, although lower than
that in the Anger camera image.
Patient analysis The ROI was semi-automatically set as
described for the clinical study (smartMIBG software,
FUJIFILM RI Pharma, Japan) [
]. The operators selected a
point at the center of the heart on the image, and then, a
circular ROI was positioned on the heart. The subsequent
processing was automatic, but can be modified manually if
the location was inappropriate. A mediastinal ROI was
determined as 30% of the height (center of the heart to the
upper border of the mediastinum) and 10% of the body width.
The circular cardiac ROI was similar to the setting in the
study using the Anger camera. Since an upper mediastinum
ROI could not be set for D-SPECT imaging, the highest
mediastinal region of the lowest average count was selected.
In a preliminary study, the inter-observer reproducibility of
average mediastinal counts in the initial 40 data points was
good, showing the first measurement = 1.01 9 the second
measurement -8 (r = 0.99, p \ 0.0001).
Conversion of HMR between Anger camera and D
To adjust HMR from D-SPECT to Anger camera
conditions, the following equation was used:
Adjusted HMR = CC of Anger camera/CC of
D-SPECT 9 (measured HMR - 1) ? 1, and the effect of
correction was examined.
In the next step, we used an MEGP collimator condition
to standardize the HMR to provide better quantitative
accuracy as stated in the European imaging proposal [
The average CC with MEGP was 0.88 [
], which is
referred to herein as ‘‘standard ME88’’. Based on the
measured CC for the system, the standardized HMR to the
ME88 condition was calculated as:
Standardized HMR = 0.88/CC of the institutional
system 9 (measured HMR - 1) ? 1.
Calculation of washout rate
Washout rate (WR) was calculated using the following
formula for both the Anger camera and D-SPECT with
early and late heart counts (Hearly, Hlate), mediastinal
counts (Mearly, Mlate), and a decay correction factor
WR ¼ ððHearly MearlyÞ
WR without background correction
¼ ðHearly Hlate=DCFÞ=Hearly
where DCF = 0.5^(difference between early and late (h)/
Data are shown as mean ± standard deviation (SD).
Differences among groups were assessed using the
oneway analysis of variance and Student’s t test. Paired
values were analyzed using paired t tests with Bland–
Altman plots and signed rank tests. Linear regression of
the HMR between the two camera conditions was
calculated using the least squares method. A variability of
the average ROI count was also examined using
coefficient of variation (CV, %). The statistics software was
JMP version 12 (SAS Institute Inc., Cary, NC, USA),
and we used Mathematica 11 (Wolfram Research Inc.,
Champaign, IL, USA) for some of the mathematical
Phantom experiments and conversion coefficients
Cardiac and mediastinal counts per minute were compared
between the Anger and D-SPECT cameras (Fig. 2). Linear
correlation was good for both cardiac and mediastinal
counts (R2 = 0.95 for both), whereas acquired counts were
higher with D-SPECT than the Anger camera. Mediastinal
count variability was similar in two groups with lower
(HMR \ 1.6) and upper (HMR [ 2.8) quartiles of HMR
distribution. In the lower quartile group, mean count/pixel/
min and CV (%) were 10.2 (22%) for Anger camera and
50.8 (23%) for D-SPECT. In the upper quartile group, they
were 12.0 (24%) for Anger camera and 62.6 (25%) for
Fig. 2 Relationship of cardiac
(a) and mediastinal (b) counts/
pixel per minute derived from
Anger camera and D-SPECT.
Circles and squares early and
late HMR, respectively. Shaded
area confidence of fit
CC conversion coefficient, HMR heart-to-mediastinum ratio, LEHR low-energy high-resolution collimator, ME88 ME collimator with conversion
coefficient of 0.88, SD standard deviation
Cross calibration of HMR ratio in the clinical study
Table 1 shows the HMR derived from the original Anger and
D-SPECT images. Paired comparisons of the HMR derived
from the original Anger and D-SPECT images showed that
the latter was significantly higher (p \ 0.0001), with a mean
difference of 0.10. When HMR from D-SPECT was
converted to the condition of the Anger camera with LEHR
collimator, the difference between two systems disappeared
(p = n. s.). Scatterplots and linear regression lines between
HMR before and after correction showed that the conversion
of HMR from D-SPECT to the Anger camera condition
improved the systematic differences between the two camera
systems (Fig. 3a, b).
Standardization to the ME88 condition similarly
eliminated the difference between the Anger and D-SPECT
findings. The average standardized HMR from the Anger
camera (StdHMRAnger) and D-SPECT (StdHMRDSPECT)
became comparable (2.21 ± 0.65 vs. 2.20 ± 0.75, p = n.
s.) (Table 1). After standardization, a bivariate correlation
plot showed good linearity: StdHMRDSPECT = -0.25 ?
1.11 9 StdHMRAnger (R2 = 0.93; Fig. 3c).
(CC = 0.55)
D-SPECT D-SPECT (CC = 0.63) to
(CC = 0.63) Anger LEHR (CC = 0.55)
D-SPECT adjusted to Anger
Anger LEHR standardized to
D-SPECT standardized to
Anger LEHR (CC = 0.55) to
Anger MEGP (CC = 0.88)
Since standardized HMRDPSECT was slightly lower in the
range of HMR \ 1.3 and slightly higher in the range of
HMR [ 2.3 (Fig. 3c) compared with the standardized
HMRAnger, further correction was attempted. As
standardized HMR with Anger camera was calculated as
StdHMRAnger = (StdHMRDSPECT ? 0.30)/1.19 in the
initial 40 data points, this regression equation was applied to
the latter 40 data points for validation. Then, the bivariate
correlation plot showed improved linearity:
StdHMRDSPECT = 0.09 ? 0.98 9 StdHMRAnger (R2 =
0.91; Fig. 4).
Washout rates from the D-SPECT and Anger cameras were
compared with and without background correction (Fig. 5).
Although they positively correlated (R2 = 0.83 and 0.65,
Adjustment of HMR to LEHR collimator condition or ME88
condition improved correspondence between both HMR (p = n. s.
for both). Circles and squares early and late HMR, respectively.
Dotted line line of identity. Shaded area confidence of fit. Solid line in
pairwise comparison plot, mean difference; dotted lines upper and
lower 95% of mean difference
p \ 0.0001, respectively), a few outliers persisted between
the values derived from both cameras.
The major purpose of this study was to create a conversion
method between Anger and D-SPECT CZT cameras. Using
CC values for D-SPECT image acquisition, we
cross-calibrated HMR between Anger and D-SPECT camera
systems and could also adjust the HMR to the ME88
condition. This cross calibration could enable the
application of HMR to multicenter studies of patients with chronic
HF and Lewy-body disease.
Need for standardization of MIBG parameters
Although HMR in a 123I-MIBG study is a simple parameter
based on the average count ratio of the heart and
mediastinum, a standardized approach is essential for diagnostic
Fig. 4 Additional correction of
HMR in the latter 40 data points
using a regression line derived
from the initial 40 data points. A
slight deviation of the line
observed in Fig. 3c was further
improved. Shaded area
confidence of fit. Solid line in
pairwise comparison plot, mean
difference; dotted lines upper
and lower 95% of mean
and prognostic evaluation [
]. Among various factors, the
influence of the collimator on HMR calculations is too
large to generate consistent results, particularly when the
collimators are of low-(LE) and medium-(ME) energy.
Several methods have been proposed, but we advocate
using a calibration phantom that can be easily applied to
any camera-collimator setting [
]. The findings of 225
phantom experiments have shown that the key
characteristics of collimators are not simply ME and LE, but can be
more precisely defined, for example, as LEHR, LE
generalpurpose (LEGP), low–medium energy (LME), MEGP, and
ME–low penetration (MELP) . Whether or not a CC
could be similarly determined for D-SPECT after the
advent of the CZT camera has remained unknown. Even if
CC could be measured, whether or not a D-SPECT HMR
could be integrated with Anger camera conditions has not
Characteristics of HMR by D-SPECT
Anterior planar image-equivalent planograms generated by
D-SPECT can serve as part of a quality control system for
projection images, which was a convenient base for this
study. Although we tried similar ROI settings, D-SPECT
has some limitations. An upper mediastinal ROI cannot be
set due to the vertical length of the view being 16 cm. We,
therefore, tried to define the highest possible mediastinal
region with the lowest average count, which corresponded
to the mid position on the Anger camera image. If the large
field of view CZT camera is available in future, the effect
of small field of view on the accuracy of ROI setting could
be validated. In addition, mediastinal count variability as
examined by CV was not significantly different between
the Anger camera and D-SPECT in patients with high and
low HMR. However, an automatic ROI processing
algorithm for D-SPECT could enhance reproducibility. The
energy resolution of the CZT camera is better, which
enabled better contrast in images derived from D-SPECT
than from the Anger camera. The Compton scatter fraction
might also differ between Anger and D-SPECT settings.
Therefore, the CC determined in this study is a practical
value with which to cross-calibrate the two camera
conditions. The planogram is unique to the single D-SPECT
system, whereas images from the Anger camera vary due to
wide disparities among camera-collimator combinations.
Although the administration dose of 123I-MIBG was
relatively low (111 MBq) compared with studies in the
North America (370 MBq) and Europe (185 MBq), the
image quality of planogram and SPECT was good by
Comparison with ADRECARD study
The ADRECARD study was the first to compare HMR
calibrated using D-SPECT and Anger cameras. A
conversion equation for HMR (Corrected D-SPECT)
= 0.5896 9 HMR (D-SPECT) ? 0.4649 was created
based on a phantom experiment in that study [
on their original table and assuming that the LEHR of
their camera collimator had a CC of 0.55, we tentatively
calculated the standardized HMR, and found a good
correlation even with our standardization method.
However, HMR (D-SPECT) ? 0.1 seemed to correlate more
closely with the standardized HMR (Anger) [
HMR calculated with the Anger camera was higher than
that in the ADRECARD study. Although agreement with
our temporary calculation was generally good in the
present study, the following factors should be considered.
To calculate HMR, the square ROI over the heart applied
in the ADRECARD study included a slight extra-cardiac
area (lower heart count than ours), and a mediastinal
rectangular region was placed in a lower position (higher
mediastinal count than ours). Our heart ROI setting in the
clinical study was circular and within the heart, and we
identified the mediastinal region with the lowest count.
As a result, the HMR calculated from the Anger camera
using our algorithm was always higher. The location of
the ROI could be a cause of variation in the clinical
]. Although the ADRECARD study used
99mTc-tetrofosmin for localization of the heart, we did
not use dual-nuclide acquisition to reduce the radiation
burden and study cost. We obtained anterior planograms
by localizing the heart by pre-test imaging for a short
period. When the field of view is inappropriately located,
measurements could be readily repeated using the
highsensitivity D-SPECT system.
low cardiac and background counts. Shaded area confidence of fit.
Solid line in pairwise comparison plot, mean difference; dotted lines
upper and lower 95% of mean difference
The difference in measured HMR between D-SPECT and
Anger camera with an LEHR collimator was smaller
compared with that between the Anger camera with LEHR
and ME collimators. The CC with D-SPECT was between
that of LEHR and LME collimators [
15, 20, 23
multicenter prognostic studies, HMR values of 1.6–1.75 were
thresholds for differentiating good and poor prognosis
including cardiac death, serious arrhythmia, and
progression of HF [
1, 2, 4, 7
]. When the linear regression line was
observed, the impact of cross calibration was relatively
small in the HMR range of \1.6. However, in the range of
borderline to higher HMR, the discrepancy was increased
between the two systems and appropriate correction
methods should be used.
In a D-SPECT study, conversion of HMR to ME88
condition using conversion coefficient (0.63) works well
around the HMR of 1.6–2.0 and can be used for clinical
studies for differentiating good and poor prognosis.
However, standardized HMR with D-SPECT showed slightly
lower values in the HMR range of \1.3 and higher values
in the HMR range of [2.3. This was probably due to lower
mediastinal background and better contrast in D-SPECT
study compared with the Anger camera condition. This
systematic difference could be further corrected if we used
regression line between standardized values. However, as
the need for additional correction may depend on the
individual D-SPECT system and acquisition conditions,
further studies should be indicated in multiple centers,
where D-SPECT is used.
If HMR could be consistently calculated in a wide range
of HMR, possibility of using D-SPECT for a mortality risk
model could be considered [
]. Since the uncorrected
D-SPECT HMR was higher than that of the Anger camera
with an LE collimator in the borderline to higher HMR
range, a corrected HMR could avoid underestimating
mortality risk, although further validation studies will be
Although the LEHR collimator is popular in the United
States, many types of collimators other than LEHR such as
LEGP, LME, MEGP, and MELP collimators are actually
used in clinical practice. Therefore, CC can be applied to
compare HMR from various conditions using the uniform
acquisition conditions, such as ME88 condition and
individual institutional LE collimator condition.
While the correlation between washout rates derived from
the Anger camera and D-SPECT was also fair,
reproducibility requires careful attention when background
subtraction is applied to very low cardiac counts as seen in
the outliers of washout rate plots between both cameras
(Fig. 5). The need for background correction when patients
have a low HMR should be further analyzed from both
diagnostic and prognostic viewpoints [
Only one D-SPECT and one Anger camera system were
included in this study. Although D-SPECT planograms
have no potential for variation, the adequacy of applying
the present results to other hospitals should be further
studied. We had already completed phantom experiments
under 225 conditions at 84 institutions [
conditions at present) in Japan by the end of 2016 and by
that time studies under 210 conditions had also proceeded
at 27 European institutions . Although CC values are
affected by specifications of the camera, collimators,
detector crystals, and acquisition conditions, we postulate
that the present findings could be applicable even for
D-SPECT compared with other camera-collimator
combinations. However, further studies are needed to validate
this phantom methodology for universal applications.
Three-dimensional SPECT quantitation was not used in the
present study. Because whole heart quantitation has been
achieved using MIBG imaging [
], the potential
variability of such three-dimensional methods including
the need for an appropriate background, dependency of the
results on software algorithm, and the relationship to
conventional planar imaging should be further investigated.
Whereas the current study confirmed that planar-equivalent
HMR can be generated from D-SPECT images, whether
this is the optimal use of the imaging capabilities of this
D-SPECT system remains to be determined. Finally, in the
clinical application, timing of the Anger and D-SPECT was
not exactly the same. However, correlation of average
counts was good between the Anger and D-SPECT
cameras, and it has been shown that variation in acquisition
time of 123I-MIBG between 2- and 4-h post-injection did
not lead to a clinically significant change in the late H/
M ratio .
The 123I-MIBG HMR can be similarly calculated with
D-SPECT using a planogram as used in planar studies with
an Anger camera. The HMR derived from D-SPECT can
be calibrated to both LE collimator and ME collimator
conditions using CC values based on institutional phantom
experiments. A slight deviation of the regression line could
be further improved using the regression line. The
crosscalibration method supports diagnostic and prognostic uses
of D-SPECT as used in Anger camera systems.
Acknowledgements We appreciate the cooperation of technologists
Shigeaki Hiko and Haruki Yamamoto. We also thank Dr. Tomofumi
Yoshinaga, Department of Neurology, Public Hospital of Matto,
Ishikawa, Hakusan, Japan for providing neurological data from the
patients and Norma Foster for editorial assistance. This study was
supported in part by Grants-in-Aid for Scientific Research in Japan
(No. 15K09947; PI, Kenichi Nakajima).
Compliance with ethical standards
Conflict of interest Kenichi Nakajima collaborates with FUJIFILM
RI Pharma Co. Ltd. (Tokyo, Japan), supplier of 123I-MIBG in Japan,
to develop software.
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