The impact of number of steps on gastrointestinal activity-related artifacts in myocardial perfusion scintigraphy

doi:10.21203/rs.3.rs-2864958/v1

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The impact of number of steps on gastrointestinal activity-related artifacts in myocardial perfusion scintigraphy

https://doi.org/10.21203/rs.3.rs-2864958/v1

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Objective. Various techniques have been used to reduce interfering extracardiac activity in myocardial perfusion imaging (MPI) with inconsistent results. The aim of this study was to investigate the effect of previously not specifically addressed monitored walking on the reduction of infracardial artifacts in the pharmacological stress Tc-99m tetrofosmin MPI with single-photon emission computed tomography (SPECT) to improve image quality.

Methods. The study was performed in 199 patients who were referred for routine 2-day stress/rest MPI and underwent pharmacological stress test. Patients were randomized into group A (n=95) and group B (n=104). Both groups were provided with a step-counter immediately after the radiotracer injection, but only group A was instructed to take at least 1000 steps before the imaging. Study participants received intervention only on stress day. Images were evaluated qualitatively and quantitatively for the interfering extracardiac artifacts. Myocardial and abdominal activity were quantitatively assessed on raw planar images, and the mean myocardium-to-abdomen count ratios were calculated. In addition, the presence of interfering activity was assessed visually on reconstructed SPECT images. The amount of extracardiac tracer activity was scored from “no tracer activity” to “severe.” Moderate and severe subdiaphragmatic tracer activity was considered relevant for the interpretation of the myocardial perfusion scan.

Results. There were no differences in clinical characteristics between the two groups. Patients in group A walked more steps than those in group B, but there were no differences in acceptance rate between the two groups. There were also no differences in proportion of subdiaphragmatic activity with a score 2 or 3 between the groups. Number of steps had no effect on acceptance rate.

Conclusions. Walking at least 1000 steps while waiting on acquisition has no impact on the gastrointestinal activity related artifacts and acceptance rate of the scans after pharmacological stress in comparison to walking on own discretion. However, the use of pedometers encourages patients to walk while waiting for imaging. Further larger studies, which would compare a group with a higher number of steps (at least 3000 steps) and a sedentary control group, are needed, to address the impact of walking on gastrointestinal artifacts in MPI.

subdiaphragmatic artifacts

myocardial perfusion imaging

single photon emission computed tomography

tetrofosmin

walking

Myocardial perfusion imaging (MPI) is an established non-invasive imaging modality for evaluating myocardial ischemia [1, 2]. After the intravenous application of the technetium-99m (99mTc) labeled radiopharmaceutical used for MPI, it is extracted from the blood by viable myocytes and is retained within the cells. In addition to the heart, it accumulates also in other organs and tissues. 99mTc-tetrofosmin is excreted through the hepatobiliary system into the intestine, resulting in the presence of subdiaphragmatic activity in the immediate vicinity of the heart [1, 3]. Thus, artifacts present on scintigrams interfere with the correct assessment of perfusion of the heart muscle, most often the inferior wall of the left ventricle. Due to vasodilation of the splanchnic vessels, which occurs during pharmacological stress test, the accumulation of radiopharmaceuticals in the abdominal organs (stomach, intestines, liver) is more pronounced than during exercise stress [1, 4–6].

The proportion of patients who require pharmacologic stress testing has been increasing over time, most commonly due to poor physical performance, inability to walk (primarily due to musculoskeletal conditions) and frailty [7]. Additionally, after the emergence of COVID-19 pandemic, American Society of Nuclear Cardiology (ASNC) and Society of Nuclear Medicine and Molecular Imaging (SNMMI) published recommendations to minimize the risk of viral exposure and transmission to healthcare personnel and patients. Several practices have been suggested, among them minimizing time of interaction between personnel and patients and maximizing distance of interaction. To minimize droplet exposure to exercise staff and minimize close contact between staff and patients the preferred stress protocol was pharmacological stress with vasodilator agents [8].

Artifacts in the inferior myocardial wall due to subdiaphragmatic activity pose a serious problem due to poorer image quality and consequently poorer diagnostic value of the study, which contributes to less optimal management of the patient. In the daily practice because of interference from the abdominal activity, repeated imaging needs to be performed in some patients that reduces the availability of gamma camera, prolongs the imaging execution time, and increases the radiation exposure of employees and those in the waiting room.

Various techniques (fasting, delayed imaging, drinking and consuming food while waiting for imaging) have been used to reduce intestinal activity in MPI with inconsistent results [4–6, 9–13].

The role of controlled physical activity by counting steps while waiting for imaging has not yet been studied. This measure could contribute to reduced number of artifacts due to accelerated peristalsis of the gastrointestinal tract after pharmacological stress test and faster release of radiopharmaceuticals from the gastrointestinal tract and therefore to a better diagnostic outcome of the study [14].

The aim of this study was to investigate the effect of intensity or amount of walking between injection of radiopharmaceutical and aquisition on image quality of SPECT MPI images in relation to subdiaphragmatic activity.

Study population

A prospective randomized-controlled trial was conducted between September 2021 and March 2022.

199 consecutive patients (able to walk at least 100 meters without rest) referred for pharmacological stress MPI to our department were enrolled in this study. Patients after the inferior myocardial wall infarction were excluded from the trial.

In addition to the data routinely obtained from these patients (anamnestic data on coronary artery disease and risk factors for ischemic heart disease, blood pressure, heart rate, electrocardiogram (ECG)), we also obtained data on waist circumference, body weight and height and calculated body mass index (BMI). The required sample size of patients was estimated to be at least 188 patients to achieve an 95% power at α = 0.05.

Consecutive patients who underwent a MPI with 99mTc- tetrofosmin (Myoview, GE Healthcare) with pharmacological stress with regadenosone (Rapiscan 400 micrograms, GE Healthcare) were randomly divided into two groups using a randomization table. The first group (Group A/Cases, n = 95) received an electronic pedometer watch and an instruction to take at least 1000 steps before imaging. The second group (Group B/Controls, n = 104) also received an electronic pedometer watch and instructions to walk at their own discretion.

This study was approved by the Medical Ethics Committee of Republic of Slovenia and all patients gave informed consent. The study was double blind for patients, data collectors and interpreters.

Image Acquisition

Acquisitions were performed at 60 minutes after the injection of 99mTc-tetrofosmin. Myocardial images were acquired in the sitting position with a triple-headed camera system (Digirad, Cardius X-ACT, California, USA) equipped with the high sensitivity fanbeam collimators (FANB). A total of 60 images were acquired on a 64 x 64 matrix over a 202° rotation with a starting position of − 38° and projection acquisition every 3.4 degrees adjusted to obtain 11000 counts per projection direction (step-and-shoot mode). A zoom of 2.5 was applied resulting in a pixel size of 6 mm. Electrocardiogram gating was performed at 8 frames per cardiac cycle, with a tolerance window of 40%.

The raw SPECT data was prefiltered with Butterworth filter (order 6, cut-off frequency 0.25), and reconstructed using a 3D OSEM algorithm. Low dose volume CT attenuation correction was used with 160 keV tube voltage and 2 mA tube current.

Assessment of interfering gastrointestinal activity

Two experienced nuclear cardiologists interpreted SPECT results visually. They accepted MPI for interpretation or decided for repeated acquisition in the case of disturbing extracardiac activity. The proportion of accepted MPI scans was collected prospectively.

Additionally, the amount of extracardiac tracer activity was also scored visually from 0 to 3 using the grading scale adapted from Albuitahi et al [15] (0-no subdiaphragmatic activity, 1-mild subdiaphragmatic activity with no effect on the visual interpretation, 2-moderate subdiaphragmatic activity with significant effect on interpretation, 3-severe subdiaphragmatic activity, interpretation is severely affected). Moderate and severe subdiaphragmatic tracer activity (2 and 3) was considered relevant for the interpretation of the myocardial perfusion scan.

Scintigrams were also assessed semiquantitatively in terms of the activity in the area of the inferior wall of the left heart ventricle and in the adjacent gastrointestinal tract. From this the ratio between the myocardial and extra-cardiac activity (MYO:EXT ratio) was calculated. Six frames out of sixty were selected from raw data planar images of the stress study of all participants. Rectangular regions of interest (ROIs) were drawn manually over the midportion of the inferior wall of the myocardium and adjacent underlying abdominal regions on each of the six projections. ROIs were 40 to 42 pixels in size and were identical in every patient for increasing reproducibility (Fig. 1). The total and average pixel counts for all ROIs were obtained and the count ratio of the activity of the inferior wall of the myocardium to that in the abdomen was calculated for each view. The mean of these calculated ratios was used to represent the final MYO:EXT ratio for each patient in a manner similar to the ones described previously [5, 9–10, 16–18].

The degree of correlation between the extracardiac activity measured semiquantitatively from projection images and the interfering activity seen by visual grading scale in the reconstructed SPECT was also evaluated.

Statistical methods

The Kolmogorov-Smirnov test was applied in all cases in order to test for normal distribution. Continuous variables are documented as mean ± standard deviation and compared with Student's t test. Categorical variables are presented as frequencies with percentages. Categorical variables (shares) were compared with the chi-squared test. Correlation between visual assesment of interferig extracardiac activity and MYO:EXT ratio was calculated with nonparametric one-way ANOVA. A p value of 0.05 or less was considered statistically significant.

Patient characteristics

We studied 199 patients (95 in group A, 104 in group B). Patients in both groups did not differ in any characteristics specified in Table 1.

Table 1

Group characteristics.
Variables	Group A (n = 95)	Group B (n = 104)	p value
Age (year, mean ± SD)	69.4 ± 8.6	70.5 ± 9.7	0.39
Sex (male/female)	49/46	53/51	0.93
BMI (kg/m², mean ± SD)	29.3 ± 4.4	29.7 ± 5.2	0.53
Waist circumference (cm)	103.3 ± 12.0	104.3 ± 13.6	0.58
Arterial hypertension, n (%)	77 (81%)	87 (84%)	0.63
Diabetes, n (%)	27 (28%)	35 (34%)	0.43
Dyslipidaemia, n (%)	72 (76%)	76 (73%)	0.66
Smoking, n (%)	14 (15%)	14 (13%)	0.79
Administered dose (MBq, mean ± SD)	471.6 ± 49.8	470.7 ± 58.8	0.55
BMI body mass index, SD standard deviation.

Effect of number of steps on interfering gastrointestinal activity

Patients in group A walked significantly more steps than patients in group B (2447 ± 842 vs 1578 ± 1147; p < 0.001), but there were no differences in acceptance rate between the two groups (p = 0.41) as well there were also no differences in proportion of subdiaphragmatic activity of score 2 or 3 (interfering artifact) between the two groups (p = 0.91). Results are summarized in Fig. 2. The groups did also not differ in the semiquantitatively measured MYO:EXT ratio (1.25 ± 0.17 vs 1.28 ± 0.16; p = 0.29).

Number of steps had no effect on acceptance rate (1904 ± 1082 in accepted scans vs 2069 ± 1114 in repeated scans; p = 0.29) or on the frequency of interfering artifacts (2075.4 ± 1149.9 in patients with interfering artifact vs 1899.7 ± 1039.1 in patients without interfering artifact; p = 0.26).

Our post hoc analysis showed that there was no significant difference in repeated scans (p = 0.78) and frequency of interfering artifacts (p = 0.67) in patients who made less than 3000 steps (n = 154) or in patients who made more than 3000 steps (n = 45).

Correlation between visual grading scale and MYO:EXT ratio

Mean values of MYO:EXT ratio were higher in lower grade levels of visually assessed extracardiac activity (Table 2). Figure 3 shows the correlation between the visual assessment of extracardiac activity and MYO:EXT ratio with calculated statistically significant relationship between them (p < 0.001).

Table 2

Mean values of MYO:EXT ratio in individual grading groups for visual assessment of interfering extracardiac activity.
Visual assessment of extracardiac activity	MYO:EXT ratio mean ± SD
Score 0 (n = 40)	1.40 ± 0.15
Score 1 (n = 53)	1.28 ± 0.15
Score 2 (n = 72)	1.23 ± 0.14
Score 3 (n = 34)	1.17 ± 0.16
MYO:EXT ratio myocardium to extra-cardiac activity ratio, SD standard deviation.

Various techniques (fasting, delayed imaging, drinking and consuming food while waiting for imaging) have been used to reduce intestinal activity in MPI with inconsistent and variable results [4–6, 9–13, 15–17, 19] and currently, there is no standard approach as to which technique is most effective in reducing the artifacts [1]. To the best of our knowledge the role of controlled physical activity by counting steps while waiting for imaging has not yet been studied.

In the current randomized study, we showed that the use of electronic pedometer watches encourages patients to walk while waiting for imaging. However, number of steps has no impact on occurrence and on the intensity of the gastro-intestinal activity related artifacts and acceptance rate of the scans after pharmacological stress. All patients who were instructed to take at least 1000 steps walked significantly more steps than patients who were instructed to walk on their own discretion. This indicates that patients need clear instructions for any measure we prescribe to them, otherwise they understand them differently.

The quality of analysis of SPECT images is influenced by technical and patient-related factors.

Our study groups differ only in number of steps. There were no differences in clinical characteristics including BMI and waist circumference between the groups which could affect the result. The importance of imaging time on image quality was already shown in previous studies [5–6, 13, 15]. Guidelines recommend imaging 15–60 minutes after injection of radiopharmaceutical with possible longer delays for stress images after vasodilators alone because of the risk of higher sub-diaphragmatic activity [1]. All our patients were scanned 60 minutes after stress test.

Therefore, in our study, we were able to adequately determine the impact of controlled walking with number of steps on the subdiaphragmatic activity.

It is known that the presence of subdiaphragmatic activity is higher after stress testing with vasodilators than after exercise stress as vasodilators increase hepatic and gastrointestinal flow [1, 5, 20]. In accordance with this finding, we anticipated that patients undergoing pharmacological stress studies would gain the most from our intervention. However, we did not confirm any benefits of a higher number of steps on reduction of subdiaphragmatic activity. There could be several reasons for these findings. Maybe the number of steps in patients form group A, who were instructed to make more than 1000 steps while waiting for imaging, was too low. We determined the number of steps arbitrarily as there were no data from the literature related to this issue. We anticipated that more than 1000 steps would be reasonable for the majority of the patients since patients referred for pharmacological stress are usually less mobile. In spite of that they walked on average almost 2500 steps, which was 1000 steps more than in patients from the control group.

We predicted that the reduction in interfering intestinal activity after walking will be a result of decreased gastrointestinal uptake of the radiotracer due to accelerated peristalsis and consequently faster release of radiopharmaceuticals from the gastrointestinal tract. Other studies showed that walking exercise had clinically important impact on gastrointestinal motility. The study of Choong-Kyun Noh et al. indicated that intensive walking (more that 3000 steps made) during bowel preparations before colonoscopy procedure leads to significantly higher bowel cleansing scores [14].

Since our patients were not specifically instructed to walk more than 3000 steps and consequently most of them did not reach this goal, this might be the reason for a lack of significant correlation between number of steps taken and the frequency of interfering artifacts.

Despite this, our post hoc analysis showed no significant differences between the group of patients who managed to reach more than 3000 steps compared to the group who made less than 3000 steps. The reason for this could be the small and insignificant number of patients reaching this goal. Namely, only 23% of patients performed more than 3000 steps, which is in line with our expectations, since patients with poorer mobility are sent to the pharmacological stress testing. The effect of intensity of walking on the quality of scans should be verified in a larger study.

The data in the literature also indicate that aerobic exercise improves intestinal motility when it is performed for several weeks [21]. A possible explanation for the negative result of our study may be that shorter periods of walking does not improve gastrointestinal motility.

To improve the validity of our study we assessed interfering gastrointestinal activity visually, with visual grading scale and also semiquantitatively with MYO:EXT ratio. MYO:EXT ratio has been studied and validated in multiple studies. In line with previous studies, our study quantified subdiaphragmatic activity with ratios of inferior wall of left ventricle myocardium to infra-cardiac region [5, 10, 16, 18]. Boz et al. showed that the MYO:EXT ratio was significantly higher in patients who were given a standard solid and fluid meal in addition to milk to enhance the volume of the stomach after the injection of tetrofosmin [16]. According to Hussain et al. [18] and Hara et al. [10] MYO:EXT ratio was found to be significantly higher in soda water group than in the control group. Peace et al. demonstrated that delayed imaging improves the mean MYO:EXT ratio [5]. The present study showed MYO:EXT ratio was not higher in anticipated group, which was instructed to make more than 1000 steps while waiting for scans. With these measurements we further confirmed our results which we obtained visually. We found that MYO:EXT ratio correlated significantly with the grade of interfering intestinal activity visually assessed by two observers. This finding is in accordance with the study performed by Peace et al. [5]. According to these results it seems reasonable for everyday clinical practice to assess subdiaphragmatic artifacts only visually as measuring of MYO:EXT ratio is very time consuming and does not provide any additional benefit in decision making for the acceptance of the scans.

Study limitations

Single-centre and single camera used in our study are the main limitations to expand our findings to other centers.

In our study both groups of patients were walking while waiting for the acquisition (there was only the difference in the number of steps performed) which might have influenced the results. It would be more optimal to study the control group without walking while waiting for the aquisition. Our decision was based on our clinical protocol where patients after radiofarmaceutical application walk at their own discretion.

We assume that the outcome of our study could have been different if the control patients were sitting while waiting for the imaging our results could be different. To definitely define the effect of walking on the subdiaphragmatic activity it would make sense to study this in the future.

Walking at least 1000 steps while waiting on acquisition has no impact on the gastrointestinal activity related artifacts and acceptance rate of the scans after pharmacological stress in comparison to walking on own discretion. However, the use of pedometers encourages patients to walk while waiting for imaging. Further larger studies, which would compare a group with higher number of steps made (at least 3000 steps) and a sedentary control group, are needed, to address the impact of walking on gastrointestinal artifacts in MPI.

ACKNOWLEDGEMENTS

We thank all doctors, radiopharmacists, technologist, nurses and other supporting staff working at our respective departments for their help in making our research projects possible.

AUTHOR CONTRIBUTIONS

The manuscript design, data analysis and main drafting was performed by the first author Anja Strok under direct supervision of the corresponding author Monika Stalc. Katja Zaletel, Maja Dolenc Novak and barbara Guzic Salobir contributed substantially to interpretation of the data. All authors provided detailed revisions during the manuscript preparation, approved the final version and are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

CONFLICT OF INTEREST STATEMENT

The authors declare that they have no conflict of interest.

ETHICAL APPROVAL

The study was approved by the National Medical Ethics Committee of Slovenia in 2021 (No. 0120-265/2021/3).

Verberne HJ, Acampa W, Anagnostopoulos C, Ballinger J, Bengel F, De Bondt P, et al; European Association of Nuclear Medicine (EANM). EANM procedural guidelines for radionuclide myocardial perfusion imaging with SPECT and SPECT/CT: 2015 revision. Eur J Nucl Med Mol Imaging. 2015;42:1929–40. https://doi.org/10.1007/s00259-015-3139-x
Sun X, Liu A, Jiang Z. The sensitivity and specificity of single photon emission computed tomography (SPECT) in the diagnosis of coronary artery disease (CAD): a meta-analysis. Int J Clin Exp Med 2017;10(4):6221–6236
Henzlova MJ, Duvall WL, Einstein AJ, Travin MI, Verberne HJ. ASNC imaging guidelines for SPECT nuclear cardiology procedures: Stress, protocols and tracers. J Nucl Cardiol. 2016;23:606–39. https://doi.org/10.1007/s12350-015-0387-x
Burrel S, MacDonald A. Artifacts and pitfalls in myocardial perfusion imaging. J Nucl Med Techol. 2006;34(4):193–211
Peace RA, Lloyd JJ. The effect of imaging time, radiopharmaceutical, full fat milk and water on interfering extra-cardiac activity in myocardial perfusion single photon emission computed tomography. Nucl Med Commun. 2005;26(1):17–24. https://doi.org/10.1097/00006231-200501000-00004
Dvorak RA, Brown RK, Corbett JR. Interpretation of SPECT/CT myocardial perfusion images: common artifacts and quality control techniques. Radiographics. 2011;31(7):2041–57. https://doi.org/10.1148/rg.317115090
Argulian E, Po JRF, Uretsky S, Kommaraju KK, Patel S, Agarwal V, et al. Comparison of the current reasons for undergoing pharmacologic stress during echocardiographic and radionucliude stress testing. J Nucl Cardiol. 2017;24(2):546–554. https://doi.org/10.1007/s12350-016-0398-2
Skali H, Murthy VL, Al-Mallah MH, Bateman TM, Beanlands R, Better N, et al. Guidance and best practices for nuclear cardiology laboratories during the coronavirus disease 2019 (COVID-19) pandemic: An Information Statement from ASNC and SNMMI. J Nucl Cardiol. 2020;27(3):1022–9. https://doi.org/10.1007/s12350-020-02123-2
Bresser PL, Sathekge MM, Makanjee CR, Wyk DV, Vorster M. A randomized-controlled study of a modified technique to reduce extracardiac activity in myocardial perfusion imaging. Nucl Med Commun. 2017;38(1):21–28. https://doi.org/10.1097/MNM.0000000000000600
Hara M, Monzen H, Futai R, Inagaki K, Shimoyama H, Morikawa M, et al. Reduction of infracardiac intestinal activity by a small amount of soda water in tehnecium-99m tetrofosmin myocardial perfusion scintigraphy with adenosine stress. J Nucl Card. 2008;15(2):241–5. https://doi.org/10.1016/j.nuclcard.2007.09.029
van Dongen AJ, van Rijk PP. Minimizing liver, bowel and gastric activity in myocardial perfusion SPECT. J Nucl Med. 2000;41(8):1315–7.
Malek H, Hedayati R, Yaghoobi N, Bitarafan-Rajabi A, Firoozabadi SH, Rastgou F. The effect of milk, water and lemon juice on various subdiaphragmatic activity-related artifacts in myocardial perfusion imaging. Res Cardiovasc Med. 2015;(4):e29235. https://doi.org/10.5812/cardiovascmed.29235
Lyngholm AM, Pedersen BH, Petersen LJ. Randomized, single-blind, factorial design study of interaction of food and time on intestinal activity in 99mTc-tetrofosmin stress myocardial perfusion scintigraphy. Nucl Med Commun. 2008;29(9):759–63. https://doi.org/10.1097/MNM.0b013e3283031af8
Noh CK, Kim IS, Lee GH, Park JW, Lee E, Park B, et al. Comparison of Effectiveness between Abdominal Vibration Stimulation and Walking Exercise for Bowel Cleansing before Therapeutic Colonoscopy. Gut and Liver. 2020;14(4):468–476. https://doi.org/10.5009/gnl19999
Albutaihi I, van der Veen L, Scholte A, Stokkel MP. The effects of early and late scanning on image quality and functional parameters in myocardial perfusion imaging. Clin Nucl Med. 2010;35(10):764–9. https://doi.org/10.1097/RLU.0b013e3181ef0963
Boz A, Yildiz A, Gungor F, Karayalcin B, Erkilic M. The volume effect of the stomach on intestinal activity on same-day exercise–rest Tc-99m tetrofosmin myocardial imaging. Clin Nucl Med. 2001;26(7):622–5. https://doi.org/10.1097/00003072-200107000-00010
Vermeltfoort IA, van Dijk AB, de Jong JA, Teule GJ, Gevers M, Verhoeven B, et al. A randomized study of the effect of carbonated water prior to myocardial SPECT. Ann Nucl Med. 2014;28(7):669–73. https://doi.org/10.1007/s12149-014-0863-4
Hussain S, Sultan FAT. Role of carbonated water technique to enhance Tc-99m tetrofosmin myocardial perfusion imaging by reducing subdiaphragmatic artefacts. Ann Nucl Med. 2020;34(10):787–792. https://doi.org/10.1007/s12149-020-01504-4
Malhotra G, Upadhye TS, Nabar A, Asopa RV, Nayak UN, Rajan MG. Can carbonated lime drink intake prior to myocardial perfusion imaging with Tc-99m MIBI reduce the extracardiac activity that degrades the image quality and leads to fallacies in interpretation? Clin Nucl Med. 2010;35(3):160–4. https://doi.org/10.1097/RLU.0b013e3181cc63a1
Molavipordanjani S, Abedi SM, Hosseinimehr SJ, Fatahian A, Mardanshahi A. The effects of pharmacological interventions, exercise, and dietary supplements on extra-cardiac radioactivity in myocardial perfusion single-photon emission computed tomography imaging. Nucl Med Comm. 2020;41(9):841–847. https://doi.org/10.1097/MNM.0000000000001226
Kim YS, Song BK, Oh JS, Woo SS. Aerobic exercise improves gastrointestinal motility in psychiatric inpatients. World J Gastroenterol. 2014 Aug 14;20(30):10577-84. https://doi.org/10.3748/wjg.v20.i30.10577

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The impact of number of steps on gastrointestinal activity-related artifacts in myocardial perfusion scintigraphy

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Version 1

Abstract

Figures

INTRODUCTION

MATERIALS AND METHODS

Study population

Image Acquisition

Assessment of interfering gastrointestinal activity

Statistical methods

RESULTS

Patient characteristics

Effect of number of steps on interfering gastrointestinal activity

Correlation between visual grading scale and MYO:EXT ratio

DISCUSSION

Study limitations

CONCLUSION

Declarations

References

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