Dopamine transporter binding in the brain is linked to irritable bowel syndrome in Parkinson's disease

BACKGROUND

Gastrointestinal symptoms are common in Parkinson's disease (PD), but their neurophysiological correlates are not well understood. We recently reported that functional gastrointestinal symptoms were not associated with asymmetry per se but might be associated with lower left striatal dopamine transporter (DAT) binding. The purpose of this study was to further investigate if specific gastrointestinal symptoms associate with monoamine transporter changes in specific striatal or extrastriatal areas.

METHODS

Ninety PD patients, who underwent DAT ¹^{2 3} I-FP-CIT SPECT imaging, were assessed using the MDS-Unified Parkinson's Disease Rating Scale part III, Rome III, and Wexner constipation score. DAT binding was calculated from striatal subregions using region-to-occipital cortex ratio. Voxel-wise analysis was used to assess the relationship between gastrointestinal symptoms and striatal DAT and extrastriatal serotonin transporter (SERT) binding.

RESULTS

Irritable bowel syndrome (IBS) criteria were fulfilled in 17 patients and were linked to higher ¹^{2 3} I-FP-CIT binding in the right posterior putamen and adjacent areas as compared to patients without IBS. No other significant associations between gastrointestinal symptoms and DAT or SERT binding were found.

CONCLUSIONS

These findings suggest that PD patients with IBS may have higher DAT binding in the right hemisphere. This finding implicates alterations of brain neurotransmitter physiology in the gastrointestinal symptoms of PD patients.

Diagnostic value of micrographia in Parkinson's disease: a study with [123I]FP-CIT SPECT

Micrographia is a common symptom of Parkinson’s disease (PD), and it may precede other motor symptoms. Despite the high prevalence of micrographia in PD, its neurobiological mechanisms are not known. Given that levodopa may alleviate consistent micrographia and that nondopaminergic essential tremor (ET) is not associated with micrographia, micrographia could possibly be used as an ancillary diagnostic method that reflects nigrostriatal dopamine function. We evaluated the usefulness of micrographia as a simple one-sentence writing test in differentiating PD from ET. A total of 146 PD patients, 42 ET patients and 38 healthy controls provided writing samples and were scanned with brain [¹²³I]FP-CIT dopamine transporter (DAT) SPECT imaging with ROI-based and voxelwise analyses. The diagnostic accuracy of micrographia was evaluated and compared to that of DAT binding. Compared to ET and healthy controls, PD patients showed micrographia (consistent, 25.6% smaller area of handwriting sample in PD compared to ET, p = 0.002, and 27.2% smaller area of handwriting compared to healthy controls, p = 0.004). PD patients showed 133% more severe progressive micrographia compared with ET patients (median b =  − 0.14 in PD, b =  − 0.06 in ET, p = 0.021). In early unmedicated cognitively normal patients, consistent micrographia showed 71.2% specificity and 87.5% sensitivity in PD versus ET differentiation, but micrographia had no correlation with striatal or extrastriatal [¹²³I]FP-CIT binding in patients with PD. The one-sentence micrographia test shows moderately good accuracy in PD versus ET differentiation. The severity of micrographia has no relationship with DAT binding, suggesting nondopaminergic mechanism of micrographia in PD.

ClinicalTrials.gov identifier: NCT02650843 (NMDAT study).

Convolutional neural networks for detection of transthyretin amyloidosis in 2D scintigraphy images

BACKGROUND

Transthyretin amyloidosis (ATTR) is a progressive disease which can be diagnosed non-invasively using bone avid [^99mTc]-labeled radiotracers. Thus, ATTR is also an occasional incidental finding on bone scintigraphy. In this study, we trained convolutional neural networks (CNN) to automatically detect and classify ATTR from scintigraphy images. The study population consisted of 1334 patients who underwent [^99mTc]-labeled hydroxymethylene diphosphonate (HMDP) scintigraphy and were visually graded using Perugini grades (grades 0-3). A total of 47 patients had visual grade ≥ 2 which was considered positive for ATTR. Two custom-made CNN architectures were trained to discriminate between the four Perugini grades of cardiac uptake. The classification performance was compared to four state-of-the-art CNN models.

RESULTS

Our CNN models performed better than, or equally well as, the state-of-the-art models in detection and classification of cardiac uptake. Both models achieved area under the curve (AUC) ≥ 0.85 in the four-class Perugini grade classification. Accuracy was good in detection of negative vs. positive ATTR patients (grade < 2 vs grade ≥ 2, AUC > 0.88) and high-grade cardiac uptake vs. other patients (grade < 3 vs. grade 3, AUC = 0.94). Maximum activation maps demonstrated that the automated deep learning models were focused on detecting the myocardium and not extracardiac features.

CONCLUSION

Automated convolutional neural networks can accurately detect and classify different grades of cardiac uptake on bone scintigraphy. The CNN models are focused on clinically relevant image features. Automated screening of bone scintigraphy images using CNN could improve the early diagnosis of ATTR.

Gastrointestinal Symptoms and Dopamine Transporter Asymmetry in Early Parkinson's Disease

Background

The neurophysiological correlates of gastrointestinal symptoms (GISs) in Parkinson's disease (PD) are not well understood. It has been proposed that in patients with a gastrointestinal origin of PD dopaminergic neurodegeneration would be more symmetric.

Objectives

The aim is to assess the associations between GISs and asymmetry of nigrostriatal dopaminergic neurodegeneration in PD.

Methods

Ninety PD patients were assessed using motor and GIS scales and ¹²³I‐FP‐CIT SPECT. We calculated the asymmetry index and the predominant side of motor symptoms and dopamine transporter (DAT) imaging defect and assessed their association with GISs.

Results

There were no significant differences in GISs between symmetric and asymmetric dopaminergic defect. Left predominant defect was related to more GIS and higher constipation scores.

Conclusions

GISs were associated with left predominant reduction in putaminal DAT binding but not asymmetry per se. It remains open whether left‐sided DAT deficit is related to more pronounced GI involvement or symptom perception in PD. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.

Bile Reflux is a Common Finding in the Gastric Pouch After One Anastomosis Gastric Bypass

INTRODUCTION

Data on postoperative bile reflux after one anastomosis gastric bypass (OAGB) is lacking. Bile reflux scintigraphy (BRS) has been shown to be a reliable non-invasive tool to assess bile reflux after OAGB. We set out to study bile reflux after OAGB with BRS and endoscopy in a prospective series (RYSA Trial).

METHODS

Forty patients (29 women) underwent OAGB between November 2016 and December 2018. Symptoms were reported and upper gastrointestinal endoscopy (UGE) was done preoperatively. Six months after OAGB, bile reflux was assessed in UGE findings and as tracer activity found in gastric tube and esophagus in BRS (follow-up rate 95%).

RESULTS

Twenty-six patients (68.4%) had no bile reflux in BRS. Twelve patients (31.6%) had bile reflux in the gastric pouch in BRS and one of them (2.6%) had bile reflux also in the esophagus 6 months postoperatively. Mean bile reflux activity in the gastric pouch was 5.2% (1-21%) of total activity. De novo findings suggestive of bile reflux (esophagitis, stomal ulcer, foveolar inflammation of gastric pouch) were found for 15 patients (39.5%) in postoperative UGE. BRS and UGE findings were significantly associated (P = 0.022). Eight patients experienced de novo reflux symptoms at 6 months, that were significantly associated with BRS and de novo UGE findings postoperatively (P = 0.033 and 0.0005, respectively).

CONCLUSION

Postoperative bile reflux in the gastric pouch after OAGB is a common finding in scintigraphy and endoscopy. The long-term effects of bile exposure will be analyzed in future reports after a longer follow-up.

TRIAL REGISTRATION

Clinical Trials Identifier NCT02882685.

Traumatic cervical spinal cord injury: a prospective clinical study of laryngeal penetration and aspiration

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

Dysphagia is a relatively common secondary complication in patients with traumatic cervical spinal cord injuries (TCSCI). The purpose of this study was to determine the incidence of aspiration and penetration in patients with acute TCSCI.

SETTING

Tampere University Hospital, Tampere, Finland.

METHODS

A total of 46 patients with TCSCI were evaluated with a videofluoroscopic swallowing study (VFSS). Rosenbek's penetration-aspiration scale (PAS) was used to classify the degree of penetration or aspiration. The medical records of each patient were systematically reviewed.

RESULTS

Of the 46 patients, 85% were male. The mean age at the time of the injury was 62.1 years. Most patients had an incomplete injury (78%), and most of them due to a fall (78%). In the VFSS 19 (41%) patients penetrated and 15 (33%) aspirated. Only 12 (26%) of the patients had a PAS score of 1 indicating that swallowed material did not enter the airway. Of the patients who aspirated, 73% had silent aspiration.

CONCLUSION

The incidence of penetration or aspiration according to VFSS is high in this cohort of patients with TCSCI. Therefore, the swallowing function of patients with acute TCSCI should be routinely evaluated before initiating oral feeding. VFSS is highly recommended, particularly to rule out the possibility of silent aspiration and to achieve information on safe nutrition consistency.

A body-sized phantom for evaluation of diffusion-weighted MRI data using conventional, readout-segmented, and zoomed echo-planar sequences

BACKGROUND

Abdominal diffusion-weighted imaging (DWI) has been rapidly increasing during the last few years. For the evaluation of new DWI techniques, the development of suitable phantoms and quality assurance methods is important.

PURPOSE

To construct a body-diameter phantom for abdominal DWI and study the impact of different acquisition options on image quality.

MATERIAL AND METHODS

A phantom with a diameter of 31 cm and a volume of 26 L was constructed, containing four samples representing a clinically relevant range of apparent diffusion coefficient (ADC) values. Measurements were carried out on 1.5T and 3.0T MRI systems using conventional echo-planar imaging (EPI), readout-segmented EPI, and zoomed EPI (3.0T) sequences. The effects of parallel imaging, coil intensity normalization, and patient-specific B1 shim (3.0T) were also examined. ADC values and signal-to-noise ratios of the samples were measured, and the level of artifacts was visually evaluated.

RESULTS

The agreement of ADC values between different acquisition options was generally good, but higher values (by 0.07 × 10(-3) mm(2)/s on the average) with readout-segmented EPI as well as ADC variations of approximately 0.1 × 10(-3) mm(2)/s in slice direction were observed. The image artifacts were reduced by using patient-specific B1 shim, readout-segmented EPI, or zoomed EPI.

CONCLUSION

The body-sized phantom demonstrated well the expected image artifacts in DWI with large field of view. The use of patient-specific B1 shim, readout-segmented EPI, or zoomed EPI improved image quality of DWI in this study.

Personal radiation doses in PET/CT facility: measurements vs. calculations

The estimation of shielding requirement of a new positron emission tomography (PET) facility is essential. Because of penetrating annihilation photons, not only radiation safety in the vicinity of patients should be considered, but also rooms adjacent to uptake and imaging rooms should be taken into account. Before installing a PET/CT camera to nuclear medicine facilities of Helsinki University Central Hospital (HUCH), a typical PET imaging day was simulated using phantoms. Phantoms were filled with 300 +/- 36 MBq of (18)F isotope and dose rates were measured at 12 central locations in the laboratory. In addition to measurements, dose rates were also calculated using guidelines of AAPM Task Group 108. The relationship between the measured and calculated dose rates was found to be good and statistically significant, using Pearson's correlation test. The evaluated monthly doses were compared with personal dosemeter readings. AAPM's report gives practical tools for evaluation of radiation shielding. Calculations can be carried out successfully for existing hospital complexes too. However, calculations should be carried out carefully, because especially doors, windows and partitions can easily cause underestimation of shielding requirements as shown in this work.

MRI quality control: six imagers studied using eleven unified image quality parameters

Quality control of the magnetic resonance imagers of different vendors in the clinical environment is non-harmonised, and comparing the performance is difficult. The purpose of this study was to develop and apply a harmonised long-term quality control protocol for the six imagers in our organisation in order to assure that they fulfil the same basic image quality requirements. The same Eurospin phantom set and identical imaging parameters were used with each imager. Values of 11 comparable parameters describing the image quality were measured. Automatic image analysis software was developed to objectively analyse the images. The results proved that the imagers were operating at a performance level adequate for clinical imaging. Some deficiencies were detected in image uniformity and geometry. The automated analysis of the Eurospin phantom images was successful. The measurements were successfully repeated after 2 weeks on one imager and after half a year on all imagers. As an objective way of examining the image quality, this kind of comparable and objective quality control of different imagers is considered as an essential step towards harmonisation of the clinical MRI studies through a large hospital organisation.