Lead-203 VMT-α-Neuroendocrine Tumor Scintigraphy: A Promising Theranostics Agent.

Targeted alpha therapy (TAT) using lead-212 (Pb-212)-labeled peptides presents an attractive option for the treatment of metastatic neuroendocrine tumors (NETs). As Pb-203 presents an accurate diagnostic surrogate to Pb-212, imaging with Pb-203-labelled peptides can be an important prerequisite to assess the feasibility of TAT with Pb-212-labelled agents. Here, we present the imaging data of a patient with metastatic NET with Pb-203 VMT-α-NET, a somatostatin receptor targeting agent, and demonstrate the matching distribution of Pb-203 VMT-α-NET with Ga-68 DOTANOC.

Normative Data of Liquid Gastric Emptying and Small-bowel Transit: A Prospective Cross-sectional Study.

Purpose of the Study: The primary objective was to establish the reference values for liquid gastric emptying and small bowel. The secondary objectives encompassed comparing the anterior view and geometric mean methods, assessing gender differences, and exploring potential correlations with age. Materials and Methods: Thirty-five consecutive healthy participants (28 females and 7 males) with a mean age of 42 ± 11 years (median, 42; range, 23-65) underwent liquid gastric emptying scintigraphy at five intervals (0, 0.5, 1, 2, and 4 h), with optional additional imaging at 24 h. Liquid gastric emptying was evaluated using percent retention and half-time (T1/2). Small-bowel transit was assessed using the index of small-bowel transit (ISBT), calculated as the ratio of terminal ileal reservoir counts to total abdominal counts at 4 h. Reference values were established based on percentiles or mean and standard deviation (SD). Rapid small-bowel transit was determined through visual inspection. Statistical analysis involved paired Samples t-test or Wilcoxon signed-rank test for comparing imaging methods, independent Samples t-test or Mann-Whitney U-test for gender comparison, and Spearman's rank correlation for assessing age-related associations. A 2-tailed P < 0.05 indicated significance. Results: Rapid liquid gastric emptying based on the geometric mean method was defined as percent retention <8% at 30 min, while delayed emptying as percent retention >33%, >20%, and >4% at 1, 2, and 4 h, respectively. The reference range of T1/2 of gastric emptying was 10-60 min. The reference value for small-bowel transit using the geometric mean method was established as ISBT >30% at 4 h, while rapid small-bowel transit was defined as the first visualization of activity in the cecum-ascending colon within 1 h. Parameters for liquid gastric emptying and small-bowel transit were notably higher in the anterior view method compared to the geometric mean method (P ≤ 0.019), except for percent retention at 2 h (P = 0.510). Nevertheless, the obtained reference values, whether based on percentiles or mean and SD, showed no notable variance between the two methods to warrant clinical significance. Gender did not display an impact on liquid gastric emptying or small-bowel transit in either method (P ≥ 0.173), and age demonstrated no significant moderate or strong correlations (Spearman's ρ ≤ 0.397). Conclusion: The study determined reference values for liquid gastric emptying and small-bowel transit through a standard gastric emptying scintigraphy protocol, avoiding additional complex procedures or extended imaging sessions. The established normative data can apply to individuals of both genders aged ≥18 years. While advocating the geometric mean method as the primary choice, the study acknowledges that in busy centers handling multiple studies with limited resources and a single-head gamma camera catering to multiple studies, the anterior view method remains a feasible alternative.

False-Positive Iodine-131 Uptake Due to Wasp Sting.

A 38-year-old woman with papillary carcinoma of the thyroid who underwent total thyroidectomy followed by high-dose radioiodine ablation was called for Iodine-131 (I-131) whole-body follow-up scan. Her follow-up scan revealed focal tracer accumulation in the lower aspect of the right posterior neck region. Her stimulated serum thyroglobulin and anti-thyroglobulin antibodies were 0.27 ng/ml and undetectable, respectively. Further clinical examination of the patient revealed a black scab in the same region. The patient revealed a history of wasp bite 2 days before iodine administration.

Predictors of appropriate therapies delivered by the implantable cardioverter-defibrillator in patients with coronary artery disease during long-term period.

This prospective study aimed to investigate the ability of cardiac autonomic nervous system (CANS) activity assessment to predict appropriate implantable cardioverter-defibrillator (ICD) therapy in patients with coronary artery disease (CAD) during long-term follow-up period. We enrolled patients with CAD and ICD implantation indications that included both secondary and primary prevention of sudden cardiac death. Before ICD implantation CANS was assessed by using heart rate variability (HRV), myocardium scintigraphy with 123I-meta-iodobenzylguanidine (123I-MIBG) and erythrocyte membranes ß-adrenoreactivity (EMA). The study's primary endpoint was the documentation of appropriate ICD therapy. Of 45 (100.0%) patients, 15 (33.3%) had appropriate ICD therapy during 36 months follow-up period. Patients with appropriate ICD therapy were likely to have a higher summed 123I-MIBG score delayed (p < 0.001) and lower 123I-MIBG washout rate (p = 0.008) indicators. These parameters were independently associated with endpoint in univariable and multivariable logistic regression. We created a logistic equation and calculated a cut-off value. The resulting ROC curve revealed a discriminative ability with AUC of 0.933 (95% confidence interval 0.817-0.986; sensitivity 100.00%; specificity 93.33%). Combined CANS activity assessment is useful in prediction of appropriate ICD therapy in patients with CAD during long-term follow-up period after device implantation.

Advancements and Challenges in Cardiac Amyloidosis Imaging: A Comprehensive Review of Novel Techniques and Clinical Applications.

Cardiac amyloidosis, characterized by amyloid fibril deposition in the myocardium, leads to restrictive cardiomyopathy and heart failure. This review explores recent advancements in imaging techniques for diagnosing and managing cardiac amyloidosis, highlighting their clinical applications, strengths, and limitations. Echocardiography remains a primary, non-invasive imaging modality but lacks specificity. Cardiac MRI (CMR), with Late Gadolinium Enhancement (LGE) and T1 mapping, offers superior tissue characterization, though at higher costs and limited availability. Scintigraphy with Tc-99m-PYP reliably diagnoses transthyretin (TTR) amyloidosis but is less effective for light chain (AL) amyloidosis, necessitating complementary diagnostics. Amyloid-specific PET tracers, such as florbetapir and flutemetamol, provide precise imaging and quantitative assessment for both TTR and AL amyloidosis. Challenges include differentiating between TTR and AL amyloidosis, early disease detection, and standardizing imaging protocols. Future research should focus on developing novel tracers, integrating multimodality imaging, and leveraging AI to enhance diagnostic accuracy and personalized treatment. Advancements in imaging have improved cardiac amyloidosis management. A multimodal approach, incorporating echocardiography, CMR, scintigraphy, and PET tracers, offers comprehensive assessment. Continued innovation in tracers and AI applications promises further enhancements in diagnosis, early detection, and patient outcomes.

Lumbar Melanoma with Sentinel Lymph Nodes in Multiple Basins - Case Report and Review of the Literature.

Intreduction: Melanoma is an extremely aggressive form of skin neoplasia, an important stage in the diagnostic and treatment is identifying the dissemination at the lymphatic level. For a more accurate staging, the sentinel lymph node biopsy technique is performed, which in most of the time addresses one, respectively 2 locations, but cases with sentinel nodes in 3 lymphatic basins have rarely been described. Case report: We present a case of melanoma located in the right lumbar region, which from the point of view of histopathological features has a Breslow index of 4.2 mm, classified in the pT4b stage. After the CT evaluation was performed, it was decided that there is indication for performing the sentinel lymph node technique and excision with a margin of safety. Scintigraphy revealed that sentinel lymph nodes were identified in 3 different regions, respectively the right axilla and bilateral inguinal. Conclusions: Melanoma located on the trunk can present different lymphatic routes for the sentinel lymph nodes, unlike that on the limbs where certain patterns are present. Identifying these lymph nodes in cases like this involves a challenge both from a diagnostic and surgical point of view.

Seracam: characterisation of a new small field of view hybrid gamma camera for nuclear medicine.

BACKGROUND: Portable gamma cameras are being developed for nuclear medicine procedures such as thyroid scintigraphy. This article introduces Seracam® - a new technology that combines small field of view gamma imaging with optical imaging - and reports its performance and suitability for small organ imaging. METHODS: The count rate capability, uniformity, spatial resolution, and sensitivity for 99mTc are reported for four integrated pinhole collimators of nominal sizes of 1 mm, 2 mm, 3 mm and 5 mm. Characterisation methodology is based on NEMA guidelines, with some adjustments necessitated by camera design. Two diagnostic scenarios - thyroid scintigraphy and gastric emptying - are simulated using clinically relevant activities and geometries to investigate application-specific performance. A qualitative assessment of the potential benefits and disadvantages of Seracam is also provided. RESULTS: Seracam's performance across the measured characteristics is appropriate for small field of view applications in nuclear medicine. At an imaging distance of 50 mm, corresponding to a field of view of 77.6 mm × 77.6 mm, spatial resolution ranged from 4.6 mm to 26 mm and sensitivity from 3.6 cps/MBq to 52.2 cps/MBq, depending on the collimator chosen. Results from the clinical simulations were particularly promising despite the challenging scenarios investigated. The optimal collimator choice was strongly application dependent, with gastric emptying relying on the higher sensitivity of the 5 mm pinhole whereas thyroid imaging benefitted from the enhanced spatial resolution of the 1 mm pinhole. Signal to noise ratio in images was improved by pixel binning. Seracam has lower measured sensitivity when compared to a traditional large field of view gamma camera, for the simulated applications this is balanced by advantages such as high spatial resolution, portability, ease of use and real time gamma-optical image fusion and display. CONCLUSION: The results show that Seracam has appropriate performance for small organ 99mTc imaging. The results also show that the performance of small field of view systems must be considered holistically and in clinically appropriate scenarios.

Aerosol Delivery Efficiency With High-Flow Nasal Cannula Therapy in Neonatal, Pediatric, and Adult Nasal Upper-Airway and Lung Models.

BACKGROUND: High-flow nasal cannula (HFNC) systems employ different methods to provide aerosol to patients. This study compared delivery efficiency, particle size, and regional deposition of aerosolized bronchodilators during HFNC in neonatal, pediatric, and adult upper-airway and lung models between a proximal aerosol adapter and distal aerosol circuit chamber. METHODS: A filter was connected to the upper airway to a spontaneously breathing lung model. Albuterol was nebulized using the aerosol adapter and circuit at different clinical flow settings. The aerosol mass deposited in the upper airway and lung was quantified. Particle size was measured with a laser diffractometer. Regional deposition was assessed with a gamma camera at each nebulizer location and patient model with minimum flow settings. RESULTS: Inhaled lung doses ranged from 0.2-0.8% for neonates, 0.2-2.2% for the small child, and 0.5-5.2% for the adult models. Neonatal inhaled lung doses were not different between the aerosol circuit and adapter, but the aerosol circuit showed marginally greater lung doses in the pediatric and adult patient models. Impacted aerosols and condensation in the non-heated HFNC and aerosol delivery components contributed to the dispersion of coarse liquid droplets, high deposition (11-44%), and occlusion of the supine neonatal upper airway. In contrast, the upright pediatric and adult upper-airway models had minimal deposition (0.3-7.0%) and high fugitive losses (∼24%) from liquid droplets leaking out of the nose. The high impactive losses in the aerosol adapter (56%) were better contained than in the aerosol circuit, resulting in less cannula sputter (5% vs 22%), fewer fugitive losses (18% vs 24%), and smaller inhaled aerosols (5 µm vs 13 µm). CONCLUSIONS: The inhaled lung dose was low (1-5%) during HFNC. Approaches that streamline aerosol delivery are needed to provide safe and effective therapy to patients receiving aerosolized medications with this HFNC system.

Can Pantoprazole be Used for Premedication in Meckel Scintigraphy?

Objectives: Meckel scintigraphy is used to diagnose Meckel's diverticulum. Previously, premedication with ranitidine was the most frequently used method to increase the accuracy of scintigraphy. However, ranitidine can no longer be used because it is banned by the Food and Drug Administration. The aim of this study was to investigate the usability of pantoprazole as a premedication instead of ranitidine in Meckel scintigraphy. Methods: Twelve New Zealand rabbits were used in this experimental study. Rabbits were divided into two groups: pantoprazole and control. Six rabbits were premedicated with pantoprazole for three days. Meckel scintigraphy was performed on all rabbits. Counts were made and compared by drawing regions of interest from the stomach walls. Results: According to the findings of this experimental study, pantoprazole significantly increased Tc-99m-pertechnetate uptake in the stomach of rabbits on both visual and quantitative evaluation. Conclusion: Pantoprazole increases the gastric wall uptake of Tc-99m-pertechnetate in rabbits and is a potential drug for premedication in Meckel scintigraphy.

Lincoln Sign: A Rare Presentation of Medication-related Osteonecrosis of the Jaw.

A 52-year-old female patient with metastatic breast cancer receiving denosumab for 7 years presented with marked diffuse tracer uptake in the mandible on Tc-99m-methylene diphosphonate bone scintigraphy, resembling the Lincoln sign. A diagnosis of medication-related osteonecrosis of the jaw (MRONJ) was confirmed, leading to immediate discontinuation of denosumab. Conservative therapy, including limited debridement and oral rinses, was initiated. MRONJ, a potential complication of bone-modifying agents, is more prevalent in advanced malignancy cases. The Lincoln sign has not been previously reported in MRONJ, emphasizing its consideration in cancer patients undergoing bone-modifying agent treatment.

Amyloid Deposition Mainly Localized in the Basal Area of the Left Ventricle in a Patient with Amyloid Transthyretin Cardiac Amyloidosis.

A 74-year-old Japanese man was admitted to our hospital for catheter ablation of paroxysmal atrial fibrillation. Transthoracic echocardiography revealed basal interventricular septal hypertrophy without apical sparing. Cardiac magnetic resonance imaging revealed late gadolinium enhancement in the hypertrophic lesions. The Kumamoto criteria was one point, and the patient had no carpal tunnel syndrome. However, technetium-99m pyrophosphate scintigraphy revealed an accumulation in the basal region of the left ventricle. A skin biopsy revealed transthyretin (TTR) amyloid deposition. A TTR gene examination revealed no variants. This case suggests that amyloid deposition in TTR may occur in the basal area of the interventricular septum.

Disseminated Carcinomatosis of the Bone Marrow from Castration-Resistant Prostate Cancer Revealed by Choline Positron Emission Tomography-Computed Tomography.

Introduction: Disseminated carcinomatosis of the bone marrow is caused by cancer metastasis to the bone marrow and is the diagnosis is very difficult by imaging. Case Presentation: We report a 75-year-old male with disseminated carcinomatosis of the bone marrow from castration-resistant prostate cancer revealed by 11C-choline positron emission tomography-computed tomography (PET/CT). Although he already received radiotherapy to the prostate, combined androgen blockade, enzalutamide and apalutamide, and external beam radiotherapy for the pelvic bone metastases, serum prostate-specific antigen (PSA) value rapidly increased from 32 ng/mL to 104 ng/mL in recent 1 month. Bone scintigraphy showed almost no abnormal uptake in the whole body, whereas 11C-choline PET/CT showed diffuse bone marrow 11C-choline uptake. The disseminated carcinomatosis of the bone marrow was diagnosed from the discordant findings between bone scintigraphy and 11C-choline PET/CT examinations and confirmed pathologically by iliac marrow biopsy pathologically. Although docetaxel therapy was started, PSA value continued rising and he died after 4 months of the diagnosis. Conclusion: The discordant findings of choline PET/CT and bone scintigraphy can diagnose disseminated carcinomatosis of the bone marrow from prostate cancer.

Influence of Aortic Arch Morphology on Renal Perfusion in Patients with Coarctation of the Aorta: An Exploratory Study.

Objectives: The configuration of the aortic arch, particularly a Gothic arch shape, in individuals with corrected coarctation of the aorta (CoA) has been associated with a decreased systolic wave amplitude across the arch, which could potentially impair renal perfusion and elevate the risk of arterial hypertension. This study aims to explore the relationship between the morphological characteristics of the aortic arch and their impact on renal perfusion in patients with CoA. Methods: Seventy-one subjects with corrected CoA underwent continuous 24 h ambulatory blood pressure monitoring, computed tomography to assess the aortic arch, and renal perfusion scanning. Subjects were stratified into three groups based on the height-to-width (H/W) ratio of their aortic arch: Group 1 with a H/W ratio of <0.65, Group 2 with a H/W ratio between 0.65 and 0.85, and Group 3 with a H/W ratio of >0.85. Results: Groups 1 and 2 (53,78% and 62.63%) presented with a higher hypertension prevalence of elevated blood pressure than Group 3 (38.89%). Notable variations were observed among the subjects in the time to peak perfusion (Tmax) in the left kidney across the groups. Group 1 showed a median Tmax at 0.27, Group 2 at 0.13, and Group 3 at -0.38 (p-value = 0.079). The differences in Tmax for the right kidney followed a similar trend but were not statistically significant (Group 1 at 0.61, Group 2 at 0.22, and Group 3 at 0.11; p-value = 0.229). Conclusions: This study suggests that variations in the aortic arch morphology might not significantly influence renal perfusion in CoA patients. This indicates the potential adaptability of the renal blood flow, which appears to compensate for reduced perfusion, thus minimizing adverse effects on the kidney function. This adaptability suggests an inherent physiological resilience, emphasizing the need for further targeted research to understand the specific interactions and impacts on treatment strategies for CoA.

A Review of Advances in Molecular Imaging of Rheumatoid Arthritis: From In Vitro to Clinic Applications Using Radiolabeled Targeting Vectors with Technetium-99m.

Rheumatoid arthritis (RA) is a systemic autoimmune disorder caused by inflammation of cartilaginous diarthrodial joints that destroys joints and cartilage, resulting in synovitis and pannus formation. Timely detection and effective management of RA are pivotal for mitigating inflammatory arthritis consequences, potentially influencing disease progression. Nuclear medicine using radiolabeled targeted vectors presents a promising avenue for RA diagnosis and response to treatment assessment. Radiopharmaceutical such as technetium-99m (99mTc), combined with single photon emission computed tomography (SPECT) combined with CT (SPECT/CT), introduces a more refined diagnostic approach, enhancing accuracy through precise anatomical localization, representing a notable advancement in hybrid molecular imaging for RA evaluation. This comprehensive review discusses existing research, encompassing in vitro, in vivo, and clinical studies to explore the application of 99mTc radiolabeled targeting vectors with SPECT imaging for RA diagnosis. The purpose of this review is to highlight the potential of this strategy to enhance patient outcomes by improving the early detection and management of RA.

Bone Scintigraphy for Guidance of Targeted Treatment of Vertebral Compression Fractures.

Background: Vertebral compression fractures (VCFs) are prevalent in the elderly population and might be the source of back pain if they are fresh and yet unhealed. In many cases, it is a diagnostic challenge to differentiate fresh VCFs from healed united fractures, which retain similar radiographic characteristics but no longer generate pain. This information is crucial for appropriate management. The aim of this study was to evaluate the role of bone scintigraphy (BS) in identifying fresh VCFs appropriate for targeted treatment when compared to the findings of Computerized Tomography (CT). Methods: We retrospectively reviewed 190 patients with back pain suspected to stem from a recent VCF that underwent both a CT and a BS and compared the imaging patterns per vertebra. Results: The studies were concordant in the majority of cases (95.5%), diagnosing 84.4% normal vertebrae, 6.4% acute VCFs, and 4.7% chronic VCFs. However, in 37 patients, 45 occult acute VCFs were only detected on BS and not on CT. Multivariate logistic regression analysis revealed that these patients were older and had lower bone density compared to the rest of the study population. Additionally, 40 patients had acute VCFs visible on CT, but with no increased or low intensity uptake on BS. These cases were associated with a shorter time period between trauma and BS, a higher prevalence of male patients, and a higher bone density. Acute VCFs with no increased uptake or low levels of uptake were found only within the first six days of the trauma. Conclusions: BS detects radiologically occult fractures and can differentiate if a radiographically evident VCF is indeed clinically active, guiding possible treatment options. To avoid missing acute VCFs, BS should be performed six days or more after the injury.

Non-contrast preoperative MRI for determining renal perfusion and visualizing renal arteries in potential living kidney donors at 1.5 Tesla.

Background: The aim of this work was to create and evaluate a preoperative non-contrast-enhanced (CE) magnetic resonance imaging (MRI)/angiography (MRA) protocol to assess renal function and visualize renal arteries and any abnormalities in potential living kidney donors. Methods: In total, 28 subjects were examined using scintigraphy to determine renal function. In addition, 3D-pseudocontinuous arterial spin labeling (pCASL), a 2D-non-CE electrocardiogram-triggered radial quiescent interval slice-selective (QISS-MRA), and 4D-CE time-resolved angiography with interleaved stochastic trajectories (CE-MRA) were performed to assess renal perfusion, visualize renal arteries and detect any abnormalities. Two glomerular filtration rates [described by Gates (GFRG) and according to the Chronic Kidney Disease Epidemiology Collaboration formula (GFRCKD-EPI)]. The renal volumes were determined using both MRA techniques. Results: The mean value of regional renal blood flow (rRBF) on the right side was significantly higher than that on the left. The agreements between QISS-MRA and CE-MRA concerning the assessment of absence or presence of an aberrant artery and renal arterial stenosis were perfect. The mean renal volumes measured in the right kidney with QISS-MRA were lower than the corresponding values of CE-MRA. In contrast, the mean renal volumes measured in the left kidney with both MRA techniques were similar. The correlation between the GFRG and rRBF was compared in the same manner as that between GFRCKD-EPI and rRBF. Conclusion: The combination of pCASL and QISS-MRA constitute a reliable preoperative protocol with a total measurement time of <10 min without the potential side effects of gadolinium-based contrast agents or radiation exposure.

Effect of access sheath diameter used in percutaneous nephrolithotomy on renal function: a prospective randomized study.

We aimed to determine the effect of the access sheath diameter used in percutaneous nephrolithotomy (PNL) on renal function. We also investigated the predictors of impaired renal function. Data were prospectively collected from patients who underwent PNL from December 2020 to December 2021. The patients were randomized into two groups according to access sheath diameter: Group 1 (22 Fr, n = 44) and Group 2 (28 Fr, n = 44). Relative renal function (RRF) was calculated by technetium-99 m dimercaptosuccinic acid scintigraphy, and glomerular filtration rate (GFR) was calculated by diethylenetriamine pentaacetic acid scintigraphy. A difference of 5% or more in RRF was considered a significant functional change. Preoperative and postoperative Kidney Injury Molecule-1 (KIM-1) levels were measured. Preoperative demographic data and stone characteristics were similar between the groups. There were also no statistically significant differences between the groups in terms of scar development, changes in RRF, GFR, or KIM-1/creatinine (Cr) (p > 0.05). Significant deterioration in RRF was detected in a total of six (6.8%) patients, three in each group. The factors predicting loss of function were analyzed by regrouping the patients without loss of function as Group A (n = 82) and those with loss as Group B (n = 6). Only stone volume was statistically significant in multivariate analysis (p = 0.002). Access sheath diameter had no significant effect on renal function after PNL. However, the stone volume was found to independently correlate to a loss of renal function after PNL.

Molecular imaging of thyroid and parathyroid diseases.

INTRODUCTION: Molecular imaging of thyroid and parathyroid diseases has changed in recent years due to the introduction of new radiopharmaceuticals and new imaging techniques. Accordingly, we provided an clinicians-oriented overview of such techniques and their indications. AREAS COVERED: A review of the literature was performed in the PubMed, Web of Science, and Scopus without time or language restrictions through the use of one or more fitting search criteria and terms as well as through screening of references in relevant selected papers. Literature up to and including December 2023 was included. Screening of titles/abstracts and removal of duplicates was performed and the full texts of the remaining potentially relevant articles were retrieved and reviewed. EXPERT OPINION: Thyroid and parathyroid scintigraphy remains integral in patients with thyrotoxicosis, thyroid nodules, differentiated thyroid cancer and, respectively, hyperparathyroidism. In the last years positron-emission tomography with different tracers emerged as a more accurate alternative in evaluating indeterminate thyroid nodules [18F-fluorodeoxyglucose (FDG)], differentiated thyroid cancer [124I-iodide, 18F-tetrafluoroborate, 18F-FDG] and hyperparathyroidism [18F-fluorocholine]. Other PET tracers are useful in evaluating relapsing/advanced forms of medullary thyroid cancer (18F-FDOPA) and selecting patients with advanced follicular and medullary thyroid cancers for theranostic treatments (68Ga/177Ga-somatostatin analogues).

Utility of Combining Transcranial Sonography and MIBG Myocardial Scintigraphy to Evaluate Substantia Nigra in Patients with Parkinson's Disease.

The utility of transcranial sonography (TCS) remains unclarified for the auxiliary diagnosis of Parkinson's disease (PD). We investigated iodine-123 metaiodobenzylguanidine (MIBG) and TCS during the examination and diagnosis of high-signal-intensity substantia nigra lesion (HSI-SNL) incidence in PD patients previously diagnosed with dopamine transporter scintigraphy (DAT). The subjects were 67 patients with definitively diagnosed PD after DAT evaluation. Patients with midbrain substantia nigra visible during TCS who previously underwent MIBG were analyzed. The SN+ group comprised patients with extensive pathological HSI-SNL of Okawa class III/IV observed during TCS. The MIBG+ group comprised patients with a heart-to-mediastinum ratio of ≤2.2 during MIBG. TCS was performed to divide patients into the SN+ and SN- groups, and patient characteristics and MIBG findings were compared between the groups. PD was definitively diagnosed in 67 patients, among whom midbrain was visualized during TCS in 43 (64.1%) patients and pathological HSI-SNL was observed in 24 (35.8%). The MIBG findings were normal in six patients (27.3%) with HSI-SNL, and abnormal in seven (63.6%) without HSI-SNL. No significant differences were noted by Okawa classification in clinical characteristics based on the presence or absence of HSI-SNL. Multiple patients with normal findings during MIBG may have HSI-SNL. Thus, confirmatory imaging of HSI-SNL with TCS may be useful for diagnosis.

Gastric Emptying Scintigraphy Protocol Optimization Using Machine Learning for the Detection of Delayed Gastric Emptying.

PURPOSE: The purpose of this study is to examine the feasibility of a machine learning (ML) system for optimizing a gastric emptying scintigraphy (GES) protocol for the detection of delayed gastric emptying (GE), which is considered a primary indication for the diagnosis of gastroparesis. METHODS: An ML model was developed using the JADBio AutoML artificial intelligence (AI) platform. This model employs the percent GE at various imaging time points following the ingestion of a standardized radiolabeled meal to predict normal versus delayed GE at the conclusion of the 4 h GES study. The model was trained and tested on a cohort of 1002 patients who underwent GES using a 70/30 stratified split ratio for training vs. testing. The ML software automated the generation of optimal predictive models by employing a combination of data preprocessing, appropriate feature selection, and predictive modeling analysis algorithms. RESULTS: The area under the curve (AUC) of the receiver operating characteristic (ROC) curve was employed to evaluate the predictive modeling performance. Several models were developed using different combinations of imaging time points as input features and methodologies to achieve optimal output. By using GE values at time points 0.5 h, 1 h, 1.5 h, 2 h, and 2.5 h as input predictors of the 4 h outcome, the analysis produced an AUC of 90.7% and a balanced accuracy (BA) of 80.0% on the test set. This performance was comparable to the training set results (AUC = 91.5%, BA = 84.7%) within the 95% confidence interval (CI), demonstrating a robust predictive capability. Through feature selection, it was discovered that the 2.5 h GE value alone was statistically significant enough to predict the 4 h outcome independently, with a slightly increased test set performance (AUC = 92.4%, BA = 83.3%), thus emphasizing its dominance as the primary predictor for delayed GE. ROC analysis was also performed for single time imaging points at 1 h and 2 h to assess their independent predictiveness of the 4 h outcome. Furthermore, the ML model was tested for its ability to predict "flipping" cases with normal GE at 1 h and 2 h that became abnormal with delayed GE at 4 h. CONCLUSIONS: An AI/ML model was designed and trained for predicting delayed GE using a limited number of imaging time points in a 4 h GES clinical protocol. This study demonstrates the feasibility of employing ML for GES optimization in the detection of delayed GE and potentially shortening the protocol's time length without compromising diagnostic power.