American College of Nuclear Medicine (ACNM) 2022 ACNM Annual Meeting Abstracts

The proceedings contain 91 papers. The topics discussed include: the new approach of COVID-19 patients with deteriorating respiratory functions using perfusion SPECT/CT imaging;increasing interest in nuclear medicine: evaluation of an educational workshop;cost-benefit analysis recommends further utilization of cardiac PET/MR for sarcoidosis evaluation;development of a nomogram model for predicting the recurrence of differentiated thyroid carcinoma patients based on a thyroid cancer database from a tertiary hospital in China;multi-center validation of radiomic models in new data using ComBat-based harmonization of features;bone scan with Tc99m-MDP, the missing link in the initial staging of muscle-invasive bladder carcinoma;and comparison of absorbed doses to kidneys calculated employing three time points and employing two time points in neuroendocrine patients undergoing Lu-177 DOTATATE therapy using planar images.

Echocardiographic phenotype in severe aortic valve stenosis with and without cardiac amyloidosis: The AMY-TAVI trial

Background: Longitudinal Strain (LS) pattern in cardiac amyloidosis (CA) typically spares the apex of the heart, which is a sensitive and specific finding that can be used to distinguish CA from other causes of left ventricular (LV) hypertrophy. RELAPS >1 suggests with high specificity CA, and shows a bright red in the apical segments of the polar map. Purpose(s): To identify differential echocardiographic characteristics of aortic stenosis (AS) with concomitant TTR-CA (AS-CA) compared to AS alone. Method(s): Patients with severe symptomatic AS undergoing TAVI were prospectively and consecutively included between Jan-19 and Dec-20. Pre-procedure, a complete echocardiogram was performed that included deformation parameters using Speckle-Tracking. Strain derived Indices accepted for CA screening were calculated: RELAPS: Relative apical LS (average apical LS/average basal+mid LS);SAB: (apical-septal/basal-septal LS);EFSR: (LVEF/GLS). After TAVI, a 99Tc-DPD scintigraphy and a proteinogram were performed to screen for CA. Result(s): 324 patients were included. The mean age was 81 yo, 52% women. 39 (12%) patients presented cardiac uptake on scintigraphy: 14 (4.3%) grade 1;13 (4%) grade 2, and 11 (3.4%) grade 3. Strain analysis could be performed in 243 patients due to acoustic window and covid19 pandemic restrictions. Echocardiographic characteristics between AS alone and those with grade 1 (AS-DTD1) and grade 2/3 (AS-CA) are shown in Table 1. Compared with AS alone, patients with AS-CA had significantly lower transvalvular gradients, although similar AVA, and low flow-low gradient (LF-LG) AS was more prevalent. AS-CA exhibited slightly worse cardiac remodeling (LV mass ind: 202 g/m2 vs 176 g/m2, p=0.032), and worse diastolic dysfunction, but without significant differences in thickness, diameters or volumes, with similar relative wall thickness (RWT: 0.53 vs. 0.51 mm, p=0.52). LVEF was similar, however myocardial contraction fraction (MCF= stroke volume/myocardial volume) and MAPSE were worse in AS-CA. GLS, RELAPS, SAB and EFSR were not different, but RELAPS >1 pattern was more prevalent in AS-CA (74% vs 44%, p=0,006) (Figure 1). Mass/strain ratio (RMS) was similar. There were no differences in size and fractional emptying of left atrium, or atrial septum thickness. Right ventricle (RV) size was similar, as well as conventional function parameters (TAPSE and S'). However, RV LS was worse in AS-CA. Pericardial effusion was more prevalent in AS-CA (25% vs 7.4%, p=0.013). In the multivariate analysis, predictors of AS-CA were: Age (OR: 1,2, p=0,02), BG (OR: 0,2, p=0,01), E/A (OR: 4,7, p=0,02), LV Mass index (OR: 1,02, p=0,04) and RELAPS >1 (OR: 0,12, p=0,01). Conclusion(s): Dual pathology of AS-AC is common in older patients referred for TAVI. Although it is more prevalent in patients with AS-CA, RELAPS>1 pattern can be present in almost 50% of patients with severe AS alone, which reduces its value as screening tool for CA in this clinical setting respect to others. (Table Presented).

Echocardiographic phenotype and prognostic value of relative apical sparing of longitudinal strain pattern in severe aortic stenosis with and without cardiac amyloidosis. The AMYTAVI study

Introduction: It is estimated that 15% of patients with AS have concomitant cardiac amyloidosis (CA). Left ventricular (LV) longitudinal strain (LS) pattern with relative apical sparing (RELAPS>1), shown as bright red in the apical segments on the polar map, has been strongly associated with CA. Its presence and its significance in AS is yet to be determined. Purpose(s): To determine the prevalence of the RELAPS>1 pattern in patients with severe AS with and without concomitant CA, and to analyze the echocardiographic phenotype associated with this strain pattern and its prognostic value. Method(s): Patients with severe symptomatic AS undergoing TAVI were prospectively and consecutively included between Jan-19 and Dec-20. Pre-procedure, a complete echocardiogram was performed that included deformation parameters using Speckle-Tracking. Strain derived Indices accepted for CA screening were calculated: RELAPS: Relative apical LS (average apical LS/average basal+mid LS);SAB: (apical-septal/basal-septal LS);EFSR: (LVEF/GLS). After TAVI, a 99Tc-PYP scintigraphy and a proteinogram were performed to screen for CA. Result(s): 324 patients were included. The mean age was 81 yo, 52% women. Strain analysis could be performed in 243 patients due to acoustic window and covid19 pandemic restrictions. Among those, 111 (46%) presented relative apical sparing (RELAPS>1). There were no differences in clinical characteristics between patients with RELAPS <1 and >1: Similar age, sex, cardiovascular risk factors and funcional class, renal function or NT-proBNP. Among patients with RELAPS>1 there was more frecuently CA with uptake grade 2 and 3 on scintigraphy (15% vs. 4.5%, P=0.006) (Figure 1). RELAPS>1 group showed greater LV hypertrophic remodeling: Thicker myocardial wall with smaller ventricular cavity, especially concentric hypertrophy;LVEF and GLS was similar, however, MAPSE and myocardial contraction fraction (MCF) were worse in RELAPS >1 group, and EFSR was significantly higher (4.2 vs 3.9, p=0.002). RELAPS >1 group had smaller aortic valve area (AVA: 0.6 vs 0.7 cm2, p=0.045), but similar transvalvular gradients due to lower stroke volume. It had larger atria and less left atrial (LA) fractional emptying, as well as higher prevalence of atrial fibrillation (AF: 41% vs 27%, p=0.03). Right ventricle (RV) size were similar, however, RV function was worse in RELAPS >1 group (TAPSE: 19 vs 21 mm, p=0.003;free Wall LS: -24 vs -27%, p=0.008). There was no difference in all-cause mortality at 1 year of follow-up between groups (6.4% vs. 6.3%, p=1). Figure 2 represents the morphological characteristics according to the LS phenotype. Conclusion(s): In severe AS, RELAPS >1 is present in almost half of the patients. It is associated with worse cardiac remodeling, as well as higher prevalence of AF. However, it wasn't associated with higher mortality at 1 year. 1 in 7 patients with AS and RELAPS >1 have concomitant ATTR CA grade 2/3.

Ventilation Perfusion Functional Difference Images in Lung Spect: A Quantitative Improvement on Ventilation Perfusion Ratio

Purpose: Ventilation (V) perfusion (Q) SPECT imaging is important in the diagnostics of lung diseases such as pulmonary embolism, chronic obstructive pulmonary disease and recently in COVID-19 lung disease. The combined assessment of ventilation and perfusion permits the identification of classical mismatched and reverse mismatched defects, especially when these two parameters are combined in one measure as the ventilation perfusion ratio. Unfortunately, the ratio is only linear for ventilation and the scale is not symmetrical regarding classical and reversed mismatches. Small perfusion values give rise to artifacts. The scaled ventilation perfusion difference is presented as an alternative. Material(s) and Method(s): VQ SPECT was performed on patients with and without defects. Kr-81m was used as a ventilation tracer and MAA labelled with Tc-99m as a perfusion tracer. Ratio is defined as V/kQ and difference as V-kQ, where k is a scaling factor. The iterative z-map method was applied for determining the scaling factor for ratio and difference images yielding a ratio of one and zero difference for matched ventilation and perfusion. Clinical thresholds for both the difference images are derived resulting in color maps of relevant mismatches with an absolute ratio larger than the arbitrary value of two. Result(s): The relative difference is in second order proportional to the logarithm of the ratio, and has a scale going from -1 to +1, where -1 is perfusion only and +1 is ventilation only. Still the diagnostic value is hampered by the fact that areas with both low perfusion and ventilation can have high ratios. Therefore, the scaled (functional) difference is presented. Ratio, relative difference and scaled difference have been investigated in ten patients and are shown for three patients (one without defects). Ratio and relative difference images suffer from a visual overexposure effect as is clearly visible for the respiratory tract. One patient with an area in a bottom lung with a very low perfusion and slightly decreased ventilation demonstrated overflow problems of the intensity in ratio images and an overestimation of the mismatched area in both the ratio and relative difference images. Conclusion(s): While the relative ventilation perfusion-difference is a promising improvement of the ventilation-perfusion ratio, because it has a symmetrical scale and is bound on a closed domain, a better diagnostic value and functionality might be obtained by utilizing the scaled functional difference. The latter one seems superior to both the relative difference and ratio.Copyright © 2023 Southern Society for Clinical Investigation.

Technegas, A Universal Technique for Lung Imaging in Nuclear Medicine: Technology, Physicochemical Properties, and Clinical Applications.

Technegas was developed in Australia as an imaging radioaerosol in the late 1980s and is now commercialized by Cyclomedica, Pty Ltd. for diagnosing pulmonary embolism (PE). Technegas is produced by heating technetium-99m in a carbon crucible for a few seconds at high temperatures (2750 °C) to generate technetium-carbon nanoparticles with a gas-like behaviour. The submicron particulates formed allow easy diffusion to the lung periphery when inhaled. Technegas has been used for diagnosis in over 4.4 m patients across 60 countries and now offers exciting opportunities in areas outside of PE, including asthma and chronic obstructive pulmonary disease (COPD). The Technegas generation process and the physicochemical attributes of the aerosol have been studied over the past 30 years in parallel with the advancement in different analytical methodologies. Thus, it is now well established that the Technegas aerosol has a radioactivity aerodynamic diameter of <500 nm and is composed of agglomerated nanoparticles. With a plethora of literature studying different aspects of Technegas, this review focuses on a historical evaluation of the different methodologies' findings over the years that provides insight into a scientific consensus of this technology. Also, we briefly discuss recent clinical innovations using Technegas and a brief history of Technegas patents.

COVID-19: How Nuclear Medicine Can Provide A Differential Diagnosis In A Very Dubious Case

Background: We present the case of a 55-year-old woman, admitted to the Infectious Disease Department of Policlinico Umberto I, Rome, in mid-March 2020, with suspicion of COVID-19 infection. Objective(s): The rRT-PCR was negative, and the following CT scan, performed to exclude false-neg-ative results and help diagnosis, was inconclusive. Method(s): It was decided to submit the patient to a 99mTc-HMPAO-labelled leukocyte scan. Result(s): This exam led to the diagnosis of infective endocarditis. Conclusion(s): In the present pandemic scenario, 99mTc-HMPAO-labelled leukocyte scan represents a reliable imaging technique for differential diagnosis with COVID-19 in patients with confusing clinical signs, possible false-negative rRT-PCR results, and inconclusive CT scan.Copyright © 2021 Bentham Science Publishers.

Last year challenge of Nuclear Medicine: medical radioisotopes supply

Aim/Introduction: 99mTc is used in about 80% of the convencional diagnostic nuclear imaging procedures and represent yearly approximately 30 million examinations/year worldwide a year in diagnostic tests in hospitals, among others by oncology, cardiology and neurology.The production of radiopharmaceuticals for use in Nuclear Medicine has a complex system. It involves carefully calculated production schedules that take into account supply, demand and many logistical operations.The aim of this study is to show how our nuclear medicine department manage the impact of the shortly 99Mo supply chain and consequently, in the 99mTc availability and other radiopharmaceuticals produced in nuclear reactora. Material(s) and Method(s): European nuclear medicine organizations had just pay attention to how the COVID-19 pandemic might affect different parts of the 99Mo supply chain when had to dealt again faced with a new problem;the shortness 99Mo production. There are only five nuclear reactors involved in the production of 99Mo on industrial scale. These aging reactors are subject to unscheduled shutdowns and longer maintenance periods making the 99Mo supply chain vulnerable. In the last few months at our nuclear medicine department we had to reinvent ourselves so as not to completely stop carrying out the previously scheduled exams and therapies. Result(s): The use of technetium generators in Europe represents about 17% - 25% of the worldwide consumption of 99Mo, representing 30,000 exams per day and about 1.1 million doses per month. The main consequences at the IPO-Porto was;Delays in diagnosis/staging, rescheduling exams, change of surgery dates (Sentinel Ganglion and Myocardial Perfusion Cardiacs), weeks of overbooking, delay in follow-up of Glomerular Filtration Rate in pre- or post-transplant patients, postponement of 131I Therapies, Scintigraphy and Whole Body Scintigraphy in patients who were already in hypothyroidism. we had to reinvent the use of 99mTc generators, change exams appointments times, reagroup exams types by defined days and other radiopharmaceutical management tools that were not commonly used. Conclusion(s): Approximately 2/3 of scheduled exams were postponed and we had to deal with weekly and daily stock updates. Our department suggest some measures and procedures that could help with future 99Mo shortages, in order to be ready in future situations and to avoid shortness of production: the creation of a centralized European radiopharmacy system, European policies to encourage long-term investment, homogenization of marketing specifications in the Member States, solid databases of radiopharmaceuticals used/ available in Europe and encouraging cooperation between other countries outside the European Union.

Proteinuria in Thin Basement Membrane Nephropathy: A Rare Finding

Hydrothorax occurs in approximately 2% of patients on peritoneal dialysis caused by migration of fluid from the peritoneal cavity into the pleural space via pleuroperitoneal fistulas. These diaphragmatic defects are usually congenital and right-sided, explaining the predominance of right-sided effusion.. Thoracocentesis with biochemical analysis of pleural fluid reveals a transudate with a very high glucose concentration. In uncertain cases, or when there is a clinical need to demonstrate the anatomy of the communication, an imaging approach such as peritoneal scintigraphy is required. 66-year-old Hispanic female with past medical history significant for end stage kidney disease on peritoneal dialysis for past 5 months, hypertension ,cerebrovascular accident with no residual deficit, and recent exposure to COVID19 presented with fever, shortness of breath, left eye gaze abnormality and + COVID PCR. She had been having issues with meeting ultrafiltration goals outpatient. On examination she has decreased breath sounds at right lung base, Abdomen non-tender with PD catheter in place with clean dressing, no pedal edema. Laboratory findings were consistent with a transudative effusion;no organisms were cultured and no malignant cells were visualized. CT failed to identify dispersal of contrast material into the right hemithorax. A nuclear isotope scan was subsequently done. Following administration of technetium 99m via the PD catheter, a high volume of radioactive dialysate was detected entering the right hemithorax. No tracer activity was seen in the left hemithorax. PD was stopped and switched to intermittent hemodialysis.Unfortunately she succumbed to covid 19 pneumonia and died few days later. 50% of the cases, a conservative approach allows reinstitution of CAPD Conservative approach with temporary cessation of peritoneal dialysis remains the first-line treatment. 1-4 months has been shown to be adequate cessation time and restarting with low volume PD. If conservative approach fails, Invasive approach with video-assisted thoracoscopic pleurodesis or diaphragmatic repair or both allows most of them to continue with CAPD

A Case of Hydrothorax Complicating Peritoneal Dialysis

Hydrothorax occurs in approximately 2% of patients on peritoneal dialysis caused by migration of fluid from the peritoneal cavity into the pleural space via pleuroperitoneal fistulas. These diaphragmatic defects are usually congenital and right-sided, explaining the predominance of right-sided effusion.. Thoracocentesis with biochemical analysis of pleural fluid reveals a transudate with a very high glucose concentration. In uncertain cases, or when there is a clinical need to demonstrate the anatomy of the communication, an imaging approach such as peritoneal scintigraphy is required. 66-year-old Hispanic female with past medical history significant for end stage kidney disease on peritoneal dialysis for past 5 months, hypertension ,cerebrovascular accident with no residual deficit, and recent exposure to COVID19 presented with fever, shortness of breath, left eye gaze abnormality and + COVID PCR. She had been having issues with meeting ultrafiltration goals outpatient. On examination she has decreased breath sounds at right lung base, Abdomen non-tender with PD catheter in place with clean dressing, no pedal edema. Laboratory findings were consistent with a transudative effusion;no organisms were cultured and no malignant cells were visualized. CT failed to identify dispersal of contrast material into the right hemithorax. A nuclear isotope scan was subsequently done. Following administration of technetium 99m via the PD catheter, a high volume of radioactive dialysate was detected entering the right hemithorax. No tracer activity was seen in the left hemithorax. PD was stopped and switched to intermittent hemodialysis.Unfortunately she succumbed to covid 19 pneumonia and died few days later. 50% of the cases, a conservative approach allows reinstitution of CAPD Conservative approach with temporary cessation of peritoneal dialysis remains the first-line treatment. 1-4 months has been shown to be adequate cessation time and restarting with low volume PD. If conservative approach fails, Invasive approach with video-assisted thoracoscopic pleurodesis or diaphragmatic repair or both allows most of them to continue with CAPD

False positive lung perfusion/ventilation scan due to rapidly resolved pulmonary abnormalities: Importance of SPECT/CT imaging

An eighty-year-old lady a with history of treated tuberculosis decades ago and polymerase chain reaction (PCR) proven COVID-19 pneumonia about four months ago was referred to our department for ventilation/perfusion scan due to deteriorating dyspnea to rule out P.E. Planar perfusion scan showed bilateral accentuated apical perfusion gradient and multiple segmental and non-segmental perfusion defects in both lungs, which were mismatched with relatively normal planar ventilation images. Perfusion SPECT images also showed multiple segmental, sub-segmental and semi-segmental perfusion defects, which proved to be concordant with consolidations, bilateral pleural effusion, right lung pneumothorax, and atelectasis which were consultant with CT findings. The ventilation SPECT/CT images also demonstrated uniform tracer activity throughout both lungs, with almost complete improvement in consolidations, lung pneumothorax, pleural effusion, and atelectasis. Our case highlights the importance of SPECT/CT imaging in avoiding false-positive interpretation of pulmonary embolism as well as the possibility for rapid resolution of the lung parenchymal abnormalities

Pre-Pandemic Sentinel Lymph Node Biopsy In Vulvar Cancer: 4-Year Single Centre Audit

Introduction and aims of the study: In early vulvar cancer, lymph node status is the most important prognostic factor. Sentinel lymph node biopsy (SLNB) is the minimally invasive procedure that lead to the most significant reduction in the classical high morbidity associated with the sistematic inguinal-femoral lymphadenectomy. Besides quality control, the aim of this study is to document the overall experience around SLNB at this referral Centre before the Covid pandemic, in order to monitor and possibly prevent future related changes. Methods: Retrospective analysis of patient files in cases where SLNB was performed as part of the treatment for vulvar cancer at the authors’ Department, from January, 2016 to December, 2019. A single surgeon performed the SLNB with the combined technique (technetium and patent blue). Data collected included demographics, pathology, accuracy, surgery and perioperative results, feasibility and survival. Results: 18 patients with vulvar squamous cell cancer were enrolled in the study. Median age was 68 years, average BMI 27.5kg/m2, 61.1% were married and Charlson score ≥5 was 55.6%. Primary site was labia majora in 44.4% and mid-line was affected in 27.8%. FIGO stage IB in 72.2% of cases, mean tumour diameter was 20.2 (7-39)mm. SLNB was bilateral in 27.8%, 1 out of 38 nodes removed was positive and average number of nodes per patient was 2.1. Mean hospital stay was 13.2 days, blood loss 72ml and no surgical complications. There was a single case of groin recurrence in 45.1 months mean follow-up time and 2 cases of non-related deaths. 33.3% and 5.6% patients had short and long-term postoperative complications, respectively, mostly infectious. Conclusions: SLNB is a reliable and safe minimally invasive technique that should be performed by experienced gynaecological oncologists in well-equipped and multidisciplinary Centres. The Covid pandemic is believed to be causing severe difficulties in the management of patients with vulvar cancer, from diagnosis to follow-up and treatment of recurrences. This study allows a future comparison with positive results at this Centre, possibly reflecting other similar scenarios in Europe.

Pulmonary Tc99m-PSMA uptake in asymptomatic COVID-19 patient: incidental finding in SPECT/CT study

Background: As there are comparative studies between 68Ga-PSMA and 99mTc-PSMA and spectrum of PSMA expression, this is the first case report that notifies distribution of 99mTc-PSMA on COVID-19 pneumonia era on the literature. Case presentation An asymptomatic 70-Y-old male who is known case of prostate adenocarcinoma underwent initial staging. SPECT/CT of the chest region reveals bilateral peripheral multifocal ground glass opacities which shows 99mTc-PSMA uptake. Diagnosis of corona virus was confirmed by positive RT-PCR. Discussion: Unexclusive role of radiotracers in nuclear medicine has an importance for wide range of applications. Comparison between 68Ga-PSMA and 99mTc-PSMA in detection of metastatic disease in prostate cancer is also under evaluation. Conclusions: This case implicates possible role of PSMA imaging in inflammation/infection process as well as necessity for lung review in hybrid imaging especially during this recent pandemic.

4DCT as first line imaging during Covid pandeminc

Aim: The Covid-19 pandemic encouraged prompt modification to clinical practice to minimise hospital attendances in an aim to minimize exposure and protection of the NHS whilst maintaining the standards of patient care. Current literature advocates that Four-Dimensional Computerised Tomography (4DCT) has equal diagnostic value as ultrasound alone or a combination of ultrasound and Sestamibi scan in the identification of abnormal parathyroid glands in the work up for surgical management of hyperparathyroidism. In response to the evolving pandemic at Addenbrookes we modified our practice and escalated 4DCT as our first line imaging. In light of this we had a unique opportunity to evaluate the diagnostic value of the currently used imaging modalities. Methods: This is a retrospective study of 270 parathyroidectomies who underwent pre-operative 4DCT (n=270), ultrasound (n= 254) and sestamibi scan (n=253). Subsequently, we assessed the accuracy of these three modalities with the of intra-operative findings, histology, postoperative calcium and PTH. Results: The sensitivity of the 4DCT was 77% in comparison to 43% sensitivity of the ultrasound alone. (p.0.05). The combined sensitivity of ultrasound and Sestamibi scan was found to be 69%. Conclusion: The implementation of 4DCT as a single modality diagnostic imaging can be considered equally effective and accurate in the diagnosis of parathyroid abnormality. Implementing this would reduce the number of diagnostic tests improving the likelihood of successful operative planning and reduce financial cost.

Mask-Related Motion Artifact on 99mTc-MIBI SPECT: Unexpected Pitfalls of SARS-CoV-2 Countermeasures.

A 61-year-old man was referred for myocardial perfusion scintigraphy (MPS) by an occupational physician to exclude coronary artery disease (CAD). The patient had a complete left bundle branch block (LBBB) that rendered the routine exercise stress test non-diagnostic, but otherwise had no history of heart diseases, good stress tolerance with no symptoms of angina, and no abnormalities in transthoracic echocardiogram, apart from contraction patterns typical for LBBB. Initial MPS, performed using technetium-labeled Sestamibi on a Discovery NM 530c camera equipped with solid-state semiconductor detectors, revealed a significant stress-induced ischemia that did not match the good overall condition of the patient. A motion detection procedure revealed significant heart motion in Z-axis during the stress study. Upon inquiry, the patient reported breathing difficulties caused by the mandatory mask, which slipped into an uncomfortable position during the study. Repeated acquisition, without motion artifacts, revealed no features of ischemia.