Scintigraphic Imaging Research Articles

Synthesis and evaluation of [177 Lu]Lu-labeled porphyrin loaded PAMAM dendrimer: Impact on tumor uptake and pharmacokinetics.

The objective of the present work is to evaluate the ability of the radiolabeled PAMAM dendrimers (polyamidoamine) towards facilitating the delivery of an in-house synthesized porphyrin derivative in the tumorous lesions to evaluate their candidature for possible application in endo-radionuclide therapy. For this, PAMAM particles were conjugated with a porphyrin derivative namely, 5,10,15,20-tetrakis-(4-carboxymethyleneoxyphenyl)porphyrin (STAP), synthesized in-house following a two-step reaction. The average number of porphyrin molecules loaded per PAMAM particle was evaluated using ultraviolet-visible spectrophotometry and was found to be approximately 2. STAP conjugated PAMAM particles were further conjugated with p-NCS-benzyl-DOTA (subsequently referred as DOTA) to facilitate radiolabeling with 177 Lu. On an average, two p-NCS-benzyl-DOTA molecules were observed to be attached per PAMAM-STAP particle. DOTA-PAMAM-STAP conjugate was radiolabeled with 177 Lu with a final radiochemical purity of >95%, which was determined by paper chromatography using two different mobile phases viz. 0.1 M sodium citrate buffer (pH 5.0) and 10 mM DTPA. Biological behavior of [177 Lu]Lu-DOTA-PAMAM-STAP conjugate was investigated in fibrosarcoma bearing Swiss mice model wherein accumulation of radiolabeled particles was observed in liver, GIT, spleen, and kidneys at 3 h post-administration. However, accumulated activity exhibited rapid clearance from majority of the organs at 24 h post-administration. [177 Lu]Lu-DOTA-PAMAM-STAP conjugate exhibited an appreciable uptake in tumor mass [6.09 ± 1.22 percentage injected activity/organ (% IA/organ)] at 3 h post-administration (p.i.) which was found to reduce to 1.05 ± 0.13 % IA/organ at 24 h post-administration. The results obtained in biodistribution studies were further corroborated through scintigraphic imaging performed in the same animal model. Despite of an appreciable accumulation in tumor mass, the lower retention of the [177 Lu]Lu-DOTA-PAMAM-STAP conjugate therein, at longer time point (24 h p.i.) may limit its possible potential as a radio-therapeutic agent and indicates towards need for further structural manoeuvring to attain favorable in vivo performance.

The effectiveness of bone scintigraphy in the management of low back pain

BackgroundBack and low back pain have been reported as one of the leading causes of activity restriction. While degenerative changes in the spine are among the common causes of low back pain, zygapophyseal (facet) joint pain is seen as the most widely accepted cause of back pain. Standard imaging modalities may have low predictive value in detecting the source of back pain. Thanks to radionuclide bone scintigraphy, painful lesions can be distinguished from age-related changes, especially in patients with chronic low back pain. In this study, we aimed to retrospectively evaluate the clinical results of facet-induced low back pain, which was confirmed by bone scintigraphy, after facet injection treatment. MethodsWe completed a retrospective review of patients who underwent diagnostic radionuclide bone scintigraphy imaging for low back pain at our institution from 2019 to 2021. Scintigraphy imaging was often performed in conjunction with traditional diagnostic imaging. The patients underwent injection at the levels that were decided by the referring physician on the basis of the clinical symptoms, the physical examination findings, and findings on existing radiologic images, with performance of bone scanning. ResultsThe patients consisted of 24 (47.1 %) males and 27 (52.9 %) females with a mean age of 44.03 ± 9.26 years (range 34–67 years) at initial symptom onset. In the bone scintigraphy, increased radioactive uptake was detected in the facet joints of the lumbar region in 33 of 51 (64.7 %) patients. Statistically significant improvement was found in VAS-ODI and SF-36 scorings in 30 patients (90.1 %) after injection in patients with increased radioactive uptake. Statistically significant improvement was found in VAS-ODI and SF-36 scorings in 12 (66.6 %) patients who had no pathological findings with imaging modalities and were injected according to physical examination. When the two groups were compared with each other, the success rate in the group with increased radioactive uptake was found to be statistically significantly higher (p < 0.01) ConclusionsApplication of this technology may lead to more reliable diagnosis and treatment of painful facet arthropathy. Appropriate diagnostic tests and determination of spinal level localization will provide satisfactory results with correct patient selection

Automated Detection of Poor-Quality Scintigraphic Images Using Machine Learning.

Objective In the present study, we have used machine learning algorithm to accomplish the task of automated detection of poor-quality scintigraphic images. We have validated the accuracy of our machine learning algorithm on 99m Tc-methyl diphosphonate ( 99m Tc-MDP) bone scan images. Materials and Methods Ninety-nine patients underwent 99mTC-MDP bone scan acquisition twice at two different acquisition speeds, one at low speed and another at double the speed of the first scan, with patient lying in the same position on the scan table. The low-speed acquisition resulted in good-quality images and the high-speed acquisition resulted in poor-quality images. The principal component analysis (PCA) of all the images was performed and the first 32 principal components (PCs) were retained as feature vectors of the image. These 32 feature vectors of each image were used for the classification of images into poor or good quality using machine learning algorithm (multivariate adaptive regression splines [MARS]). The data were split into two sets, that is, training set and test set in the ratio of 60:40. Hyperparameter tuning of the model was done in which five-fold cross-validation was performed. Receiver operator characteristic (ROC) analysis was used to select the optimal model using the largest value of area under the ROC curve. Sensitivity, specificity, and accuracy for the classification of poor- and good-quality images were taken as metrics for the performance of the algorithm. Result Accuracy, sensitivity, and specificity of the model in classifying poor-quality and good-quality images were 93.22, 93.22, and 93.22%, respectively, for the training dataset and 86.88, 80, and 93.7%, respectively, for the test dataset. Conclusion Machine learning algorithms can be used to classify poor- and good-quality images with good accuracy (86.88%) using 32 PCs as the feature vector and MARS as the classification model.

Initial Testing of an Approximated, Fast Calculation Procedure for Personalized Dosimetry in Radionuclide Therapy Based on Planar Whole-Body Scan and Monte-Carlo Specific Dose Rates from the OpenDose Project.

Individualized dosimetry in nuclear medicine is currently at least advisable in order to obtain the best risk–benefit balance in terms of the maximal dose to lesions and under-threshold doses to radiosensitive organs. This article aims to propose a procedure for fast dosimetric calculations based on planar whole-body scintigraphy (WBS) images and developed to be employed in everyday clinical practice. Methods: For simplicity and legacy reasons, the method is based on planar imaging dosimetry, complemented with some assumptions on the radiopharmaceutical kinetics empirically derived from single-photon emission tomography/computed tomography (SPECT/CT) image analysis. The idea is to exploit a rough estimate of the time-integrated activity as has been suggested for SPECT/CT dosimetry but using planar images. The resulting further reduction in dose estimation accuracy is moderated by the use of a high-precision Monte-Carlo S-factor, such as those available within the OpenDose project. Results: We moved the problem of individualized dosimetry to a transformed space where comparing doses was imparted to the ICRP Average Male/Female computational phantom, resulting from an activity distribution related to patient’s pharmaceutical uptake. This is a fast method for the personalized dosimetric evaluation of radionuclide therapy, bearing in mind that the resulting doses are meaningful in comparison with thresholds calculated in the same framework. Conclusion: The simplified scheme proposed here can help the community, or even the single physician, establish a quantitative guide-for-the-eye approach to individualized dosimetry.

Equine skeletal scintigraphy: Comparing normal bone-to-soft tissue ratio 2 and 4 hours after injection with either hydroxymethylene diphosphonate ormethylene diphosphonate.

In equine skeletal scintigraphy, there is no information about the possible influence of different phosphonate compounds on image quality. This prospective randomised study determined bone uptake changes and image quality for hydroxymethylene diphosphonate (HDP) and methylene diphosphonate (MDP) in equine patients at different time points. Scintigraphic images of the radius and the tibia of 20 horses were acquired at 2 and 4 hours after injection of either technetium-labelled HDP or MDP. Three regions of interest were identified-in the bone diaphysis, adjacent soft tissue and background area-to determine the normal bone-to-soft tissue ratio (BSR). Qualitative analysis was performed using a modified scoring system. In terms of BSR and count rates, HDP showed a slightly better incorporation into bone compared to MDP, but significant differences were only detected for count rates at 4 hours after injection (p = 0.048). The radiopharmaceutical used did not influence qualitative image scoring, which was correlated with the BSR (ρ = 0.49; p ≤ 0.001). The choice of HDP or MDP for equine skeletal scintigraphy does not seem to substantially affect BSR and qualitative image scoring. Further studies with a larger sample size, including the evaluation of lesion detection ability for both bone-seeking agents, are needed.

An efficient segmentation technique for skeletal scintigraphy image based on sharpness index and salp swarm algorithm

Automatic Segmentation of skeletal scintigraphy images is an essential step for diagnosing bone metastasis and allowing definitive treatment. However, automatic segmentation of skeletal scintigraphy images is a challenging task due to the variance of the intensity distribution in different bones of the skeleton. This paper presents a multi-threshold technique to segment the dark spots of scintigraphy images. It segments the skull, the trunk, and the lower limbs separately rather than the whole skeletal scintigraphy image. Firstly, a sharpness index for each of the three parts is evaluated, and then an optimal threshold is computed using the salp swarm algorithm (SSA) with a fitness function based on maximizing the tsallis entropy function for each part. The proposed technique is implemented and applied with several different measures to an Egyptian medical dataset collected from Menoufia University Hospital. It is a real dataset, not standard dataset, that is a significantly addition to the research. It has its problems and drawbacks, which we are working to improve such as the invisible dark parts resulting from different external factors. The proposed technique is compared to the state-of-the-art techniques after applying the collected skeletal scintigraphy dataset to these techniques. Experimental results show that the proposed technique achieves superior performance in almost metrics such as mean square error (MSE), peak signal to noise ratio (PSNR), precision, recall, accuracy, normalized absolute error (NAE), Jaccard index, dice coefficient, matthews correlation coefficient (MCC), F1-Score, and structural similarity index matrix (SSIM).

Quantitative Scintigraphy Imaging of Lingual Raynaud’s Phenomenon Using 3-Dimensional-Ring Cadmium-Zinc-Telluride Single-Photon Emission Computed Tomography/Computed Tomography

Perfusion scintigraphy with the acquisition of planar blood flow and pool images of bilateral hands has been used to aid diagnosis and to evaluate treatment response to Raynaud’s phenomenon (decreased blood flow to hand or foot). However, because of the difficulty in imaging the tongue area with a conventional gamma camera, perfusion scintigraphy imaging of patients with lingual Raynaud’s phenomenon has yet to be reported. Here, we report the case of a 59-year-old man with lingual Raynaud’s phenomenon in which blood pool imaging of the tongue was performed using three-dimensional (3D)-ring cadmium-zinc-telluride (CZT) single-photon emission computed tomography/computed tomography (SPECT/CT). During follow-up, the patient’s lingual symptoms had worsened, and follow-up blood pool SPECT/CT images also revealed decreased blood pool uptake of the tongue, showing a decreased blood pool of more than 25% on quantitative analysis. This case suggests that blood pool imaging of the tongue using 3D-ring CZT SPECT/CT has clinical significance in evaluating patients with lingual Raynaud’s phenomenon.

Factors Associated With Radioactive Iodine Therapy–Acquired Nasolacrimal Duct Obstruction

ObjectiveTo identify factors associated with radioactive iodine (RAI)-acquired nasolacrimal duct obstruction (NLDO). MethodsRetrospective chart review and telephone surveys of patients who received RAI therapy for thyroid carcinoma at an academic institution were conducted. Telephone surveys were used to screen for post-RAI NLDO diagnoses. Databases were reviewed for documented NLDO, demographics, RAI dose, total number of RAI treatments, and sialadenitis. Routine post-RAI whole-body scintigraphy (WBS) images were analyzed for the presence or absence of 131I sodium iodide (I-131) in the nasolacrimal duct. Intranasal I-131 activity was graded as none, low, moderate, and high; those with moderate or high activity were considered to have “increased” activity. Logistic and ordinal logistic regression models were used to evaluate the associations with NLDO while adjusting for I-131 dose. ResultsOf the 209 patients who completed the survey, 15 (7%) had NLDO diagnoses. Increased intranasal I-131 activity on WBS, presence of nasolacrimal I-131 WBS activity, presence of documented post-RAI sialadenitis, and history of >1 RAI treatment were associated with the development of NLDO from univariate analyses (P ≤ .013). After adjusting for the administered dose of I-131, the presence of sialadenitis and nasolacrimal I-131 activity on WBS were the remaining 2 factors significantly associated with NLDO development (P < .001 and P = .01, respectively). ConclusionsThe presence of sialadenitis and nasolacrimal I-131 activity on WBS are I-131 dose-independent correlative factors for RAI-associated NLDO. Patients with these characteristics should be counseled on their increased risk of NLDO after RAI therapy for thyroid carcinoma.

Single-time-point estimation of absorbed doses in PRRT using a non-linear mixed-effects model

IntroductionEstimation of accurate time-integrated activity coefficients (TIACs) and radiation absorbed doses (ADs) is desirable for treatment planning in peptide-receptor radionuclide therapy (PRRT). This study aimed to investigate the accuracy of a simplified dosimetry using a physiologically-based pharmacokinetic (PBPK) model, a nonlinear mixed effect (NLME) model, and single-time-point imaging to calculate the TIACs and ADs of 90Y-DOTATATE in various organs of dosimetric interest and tumors. Materials & MethodsBiokinetic data of 111In-DOTATATE in tumors, kidneys, liver, spleen, and whole body were obtained from eight patients using planar scintigraphic imaging at T1 = (2.9 ± 0.6), T2 = (4.6 ± 0.4), T3 = (22.8 ± 1.6), T4 = (46.7 ± 1.7) and T5 = (70.9 ± 1.0) h post injection. Serum activity concentration was measured at 5 and 15 min; 0.5, 1, 2, and 4 h; and 1, 2, and 3 d p.i.. A published PBPK model for PRRT, NLME, and a single-time-point imaging datum at different time points were used to calculate TIACs in tumors, kidneys, liver, spleen, whole body, and serum. Relative deviations (RDs) (median [min, max]) between the calculated TIACs from single-time-point imaging were compared to the TIACs calculated from the all-time-points fit. The root mean square error (RMSE) of the difference between the computed ADs from the single-time-point imaging and reference ADs from the all-time point fittings were analyzed. A joint root mean square error RMSEjoint of the ADs was calculated with the RSME from both the tumor and kidneys to sort the time points concerning accurate results for the kidneys and tumor dosimetry. The calculations of TIACs and ADs from the single-time-point dosimetry were repeated using the sum of exponentials (SOE) approach introduced in the literature. The RDs and the RSME of the PBPK approach in our study were compared to the SOE approach. ResultsUsing the PBPK and NLME models and the biokinetic measurements resulted in a good fit based on visual inspection of the fitted curves and the coefficient of variation CV of the fitted parameters (<50%). T4 was identified being the time point with a relatively low median and range of TIACs RDs, i.e., 5 [1, 21]% and 2 [−15, 21]% for kidneys and tumors, respectively. T4 was found to be the time point with the lowest joint root mean square error RMSEjoint of the ADs. Based on the RD and RMSE, our results show a similar performance as the SOE and NLME model approach. SummaryIn this study, we introduced a simplified calculation of TIACs/ADs using a PBPK model, an NLME model, and a single-time-point measurement. Our results suggest a single measurement might be used to calculate TIACs/ADs in the kidneys and tumors during PRRT.

Inflammation scintigraphy imaging through a novel antimicrobial peptide labeled with technetium-99m in an animal model

Purpose Antimicrobial peptides (AMPs), due to their biological properties, have great potential for radiopharmaceutical development. In this research, a new antimicrobial peptide, derived from a 21-residue antimicrobial peptide microcinJ25 (MccJ25), was utilized to diagnose inflamed sites in mice bodies after labeling with [99mTc]Tc. Materials and methods An antimicrobial peptide derivative was connected with an efficient chelator, hydrazinonicotinamide, and then labeled with [99mTc]Tc. The binding of labeled microcinJ25 conjugate to lymphocyte was investigated in vitro. Turpentine oil-induced inflammation uptake and tissue distribution were assessed through the animal pattern. Detector scanning was done through scintigraphy post injection of [99mTc]Tc-radiopeptide within different time points. Results High radiochemical purity (>98%) was obtained for [99mTc]Tc-radiopeptide. Lymphocyte binding assessment showed specific cell binding. Binding Inhibition was observed when additional unlabeled conjugate was used. In in vivo biological distribution studies, the uptake for inflamed tissue was 1.52 ± 0.12%ID/g. The inflammation site was visualized by scintigraphy imaging at 1 up to 2 hours. Conclusion Based on our results this new designed [99mTc]Tc-radiopeptide was able to detect inflammation sites early and with high resolution, and could be considered a promising diagnostic candidate in inflammatory diseases.

ОСОБЕННОСТИ РАДИОНУКЛИДНОЙ ДИАГНОСТИКИ СИГНАЛЬНЫХ ЛИМФАТИЧЕСКИХ УЗЛОВ У БОЛЬНЫХ РАКОМ МОЛОЧНОЙ ЖЕЛЕЗЫ С ПОМОЩЬЮ НОВОГО ОТЕЧЕСТВЕННОГО РАДИОФАРМПРЕПАРАТА НА ОСНОВЕ ОКСИДА АЛЮМИНИЯ, МЕЧЕННОГО 99mТс

Purpose: To study the possibility of using [99mТс]-Al2O3 for the diagnosis of sentinel lymph nodes (SLN) in patients with breast cancer, to analyze the results obtained in comparison with a phytate colloid labeled with 99mTc. Material and methods: The study included 86 patients with breast cancer. [99mTc]-phytate colloid (31 patients) and [99mТс]-Al2O3 (55 patients) were used as radiopharmaceutical. Results: The optimal time interval between the injection of [99mТс]-Al2O3 and the acquisition of a scintigraphic image was determined to be 18-20 hours, when the maximum possible number of lymph nodes (LNs) with the most optimal level of radioactivity for their detection is visualized. In the group of patients who were injected with [99mTc]-phytate colloid, SLN were visualized in 27 out of 31 patients, a total of 37 LNs were detected in this group. The median number of detected LNs in one patient was 1 [0–3], the intensity of accumulation of [99mTc]-phytate colloid according to single-photon emission computed tomography (SPECT) was 1.75% [0.5–4.3%], intraoperatively using gamma -probe – 2.95% [1.1–5.6%]. When [99mТс]-Al2O3 was used as radiopharmaceutical, SLNs were detected in 51 patients out of 55. In total, 111 LNs were detected in this group, the median number of detected LNs in one patient was 2 [0-6], the intensity of accumulation of [99mТс]-Al2O3 according to SPECT data – 6.1% [0.5–18.4%], intraoperatively – 7.2% [1.3–22.1%]. In the absence of radiopharmaceuticals accumulation in regional LNs (n=7 in total), 3 patients had total metastatic lesions of the SLN, in two of them other regional LNs were also affected by metastases. Conclusion: A comparative analysis of the indices of two radiopharmaceuticals shows that studies with [99mТс]-Al2O3 are characterized by statistically significantly higher accumulation rates in the SLN compared with [99mTc]-phytate colloid. The number of detected LNs when using [99mТс]-Al2O3 was also higher than in the group with [99mTc]-phytate colloid. As a result, when [99mТс]-Al2O3 is used, the method is characterized by higher sensitivity in detecting SLN (94.5%).

MID ILEAL DUPLICATION CYST WITH ECTOPIC GASTRIC MUCOSA DETECTED BY TECHNETIUM-99M PERTECHNETATE

Gastrointestinal duplication cysts are a rare congenital malformation in the gastrointestinal tract, most commonly seen in the ilium. The present study reported a child with a mid ileal duplication cyst ofthe ectopic gastric mucosa that was diagnosed by Technetium-99m pertechnetate single-photon emission computed tomography-computed tomography (SPECT-CT) scintigraphy. Gastrointestinal duplication cysts can present with massive lower gastrointestinal bleeding in early childhood Technetium-99m pertechnetate (Meckel scan) with SPECT-CT can help reach the diagnosis and decrease morbidity and mortality.

Medial Tibial Stress Syndrome: A Review Article.

Leg pain caused by recurrent stressors is known as shin pain, also known as the medial tibial stress syndrome (MTSS). Athletes, particularly runners, are more vulnerable. As a result, runners devote little time to practice and avoid exercises completely. The precise cause is yet to be identified. Microdamage caused by recurrent stressors has been proposed as the fundamental mechanism in other investigations. Gender, navicular bone loss, higher body mass index, activities of high intensity, and increased range in external hip rotation in males are all risk factors. A common complaint is a bilateral pain in the distal leg, primarily on the anterior and medial sides. Pain is exacerbated by activity and eased by relaxation. Particularly, pain and swelling in the posterior and medial aspects of the tibia, as well as other causative symptoms, may be discovered during the examination. To rule out alternate origins of the same symptoms, imaging modalities such as computed tomography, radiography, bone scintigraphy, and magnetic resonance imaging might be used. Preventative measures include shock-absorbing insoles, repetitive stress avoidance, and effective treatment of repetitive stress disorder and anatomical abnormalities. Rest, ice, and pain medications are the most common treatments.

Contrast Enhancement of Scintigraphic Image Using Fuzzy Intensification.

The objective of this study was to see the effect of fuzzy intensification (INT) operator on enhancement of scintigraphic image. Nuclear medicine physician (NMP) provided 25 scintigraphic images that required enhancement. The image pixels value was converted into fuzzy plane and was subjected to contrast INT operator with parameters of INT operator i.e., cross-over = 0.5 and number of iterations = 1 and 2. The enhanced image was again brought back into spatial domain (de-fuzzification) whose intensity value was in the range 0-255. NMP compared the enhanced image with its input image and labeled it as acceptable or unacceptable. The quality of enhanced image was also accessed objectively using four different image metrics namely: Entropy, edge content, absolute mean brightness error and saturation metrics. Most of the enhanced images (18 out of 25 images) obtained at cross-over = 0.5 and number of iterations = 1 are acceptable and found to have overall better contrast compared to the corresponding input image. Four images (two brain positron emission tomography scan and two I-131 scan) obtained at cross-over = 0.5 and with iteration = 2 are acceptable. Three input images (one dimercaptosuccinic acid (DMSA), one I-131 and one I-131- metaiodo-benzyl-guanidine (MIBG) scan) were better than their enhanced images. The enhancement produced by fuzzy INT operator was encouraging. Majority of enhanced images were acceptable at cross-over = 0.5 and number iterations = 1.

Census of Cardiac Uptake on Routine Bone Scintigraphy, a Methodology to Assess the Prevalence of the TTR Amyloidosis

Objective: Transthyretin cardiac amyloidosis is a rapidly progressive disease, remains underdiagnosed, and has long been considered a rare disease. Diagnosis decision making cannot be based on echography and MRI findings alone because they lack accuracy. However, it requires invasive test of myocardial or fat pad biopsies. Thus, the diagnosis is challenging, and the non-invasive scintigraphic technique using bone-seeking radiopharmaceuticals has become a cornerstone in the workup revealing a myocardial uptake. Our work consists of a single institution retrospective study aiming to estimate the bone scintigraphies, and the prevalence of the transthyretin cardiac amyloidosis in our population. Methods: We have carried out a census of the incidental cardiac uptake on routine bone scintigraphy in 2211 consecutive patients enrolled between 2009 and 2020, mostly performed for oncologic purposes. The visual analysis of the scintigraphic images classifies the cardiac uptake into 3 levels of gradation and evokes the diagnosis of the TTR cardiac amyloidosis in grades 2 and 3. Results: Different grades of myocardial uptake were observed in 1.37 % of all patients. Prevalence of uptake was 0.37% in the 50th, increased dramatically at the 60th (2.49%), and reached 4% above the age of 80. The diagnostic grades 2 and 3 cardiac uptakes were identified in 5 patients (0.23% of overall patients) ranging between 56- and 91-y-old. Our results concord with the trend of disease increases with age. Conclusion: The careful analysis of the bone scintigraphy of all incoming adult patients should allow to make the diagnosis of the TTR cardiac amyloidosis at a preclinical stage and establish new effective treatments. Our results provide an estimate of the number of patients that could be diagnosed and improve the awareness of the corresponding prevalence in our population. In this way, multicentric studies should be implemented by enrolling large cohorts of bone scintigraphy cases.

Refractory postoperative Staphylococcus hominis bacteremia in a patient with an ACTH-producing pancreatic neuroendocrine neoplasm: a case report

BackgroundStaphylococcus hominis (S. hominis) is an opportunistic pathogen that is often highly resistant to antibiotics and is difficult to treat. In patients diagnosed with an adrenocorticotropic hormone (ACTH)-producing tumor that compromises the immune system due to hypercortisolemia, cancer treatment and infection control should be considered simultaneously. This report presents a case of refractory postoperative S. hominis bacteremia requiring the prolonged administration of several antibiotics in a patient with an ACTH-producing pancreatic neuroendocrine neoplasm (pNEN).Case presentationA 35-year-old man visited a neighboring hospital for a thorough examination after experiencing weight gain and lower limb weakness for several months. Enhanced computed tomography revealed a pancreatic tail tumor and bilateral adrenal enlargement. Elevated plasma ACTH and serum cortisol were noted. Biopsy under endoscopic ultrasonography revealed the tumor as an ACTH-producing pNEN. The patient was transferred to our hospital for further treatment. Pneumocystis pneumonia was noted and treated with sulfamethoxazole and adjunctive glucocorticoids. Hypercortisolism was controlled with metyrapone and trilostane. Somatostatin receptor scintigraphy and ethoxybenzyl magnetic resonance imaging detected other lesions in the pancreatic head. A total pancreatectomy was performed given that the lesions were found in both the pancreatic head and tail. Plasma ACTH and serum cortisol levels decreased immediately after the resection. Pathological examination revealed that the pancreatic tail tumor was NEN G2 and T3N1aM0 Stage IIB and the pancreatic head lesions were SSTR-positive hyperplasia of the islet of Langerhans cells. On postoperative day 11, catheter-associated bacteremia occurred. Initially, meropenem hydrate and vancomycin hydrochloride were administered empirically. S. hominis was identified and appeared sensitive to these antibiotics according to susceptibility testing. However, S. hominis was repeatedly positive in blood cultures for more than one month, despite treatment with several antibiotics. Eventually, with the combined use of three antibiotics (meropenem hydrate, vancomycin hydrochloride, and clindamycin phosphate) for more than 3 weeks, the S. hominis-associated bacteremia improved. He was discharged 79 days after surgery.ConclusionsOur patient with an ACTH-producing pNEN was immunocompromised and needed meticulous attention for infectious complications even after successful tumor removal. Specifically, S. hominis bacteremia in such patients demands intensive treatments, such as with combinational antibiotics.

Development of a scatter correction technique for planar 99mTc-MAA imaging to improve accuracy in lung shunt fraction estimation

PurposePrior to 90Y selective internal radiation therapy (SIRT) treatment, 99mTc-MAA scintigraphy imaging is used in the estimation of the lung shunt fraction (LSF). Planar imaging is recommended for determining a LSF ratio. However, the estimate may be affected by scatter contributions, attenuation and respiratory motion. The objective of this study was to correct for the effects of scatter in the LSF, towards the determination of a more accurate estimation method of LSF derived from planar scintigraphy imaging, which is recommended by international guidelines. MethodsThe open access SIMIND Monte Carlo modelling software was used to estimate an optimum scatter window (SW) for scatter correction. The uncertainties associated with scatter and scatter contributions from the liver on the LSF were evaluated using an anthropomorphic thorax phantom and a virtual Vox-Man phantom. A brief retrospective examination of patient scans and tumour location investigated the impact that the inclusion of the simulated scatter corrections had on the LSF estimation. ResultsThe percentage overestimation of the manufacturer recommended method of LSF estimation was 192%. SW corrections improved the uncertainty to within 19% for the range of known LSFs. Similar findings were observed for our patient and tumour location studies. ConclusionThe incorporated scatter corrections can significantly improve the accuracy of the LSF estimation, thereby providing a robust gamma camera, patient and tumour depth specific correction which is easily implementable. This is supported by Monte Carlo, phantom and preliminary patient studies.

Effectiveness of Iodine-123 β-methyl-P-iodophenyl-pentadecanoic acid (BMIPP) Myocardial Scintigraphy for Cancer Therapeutics-Related Cardiac Dysfunction (CTRCD) in Breast Cancer Patients.

Purpose: The optimal imaging modality for evaluating Cancer Therapeutics-Related Cardiac Dysfunction (CTRCD) other than echocardiography is currently not known. We conducted a retrospective study utilizing myocardial scintigraphy to detect early-stage CTRCD in asymptomatic breast cancer patients.Patients and Methods: Fifty-five asymptomatic breast cancer patients who had received chemotherapy within three years were involved in this study. Echocardiography was performed for all patients before and during chemotherapy. Thallium (201Tl) and 123I-β-methyl-P-iodophenyl-pentadecanoic acid (123I-BMIPP) myocardial perfusion and metabolism scintigraphy were performed for all patients. Scintigraphy images were reviewed by several doctors including cardiologists, radiologists, palliative care physicians, and breast surgeons. The visual image assessment was then compared with the automated analysis utilizing Heart Risk View-S software (Nihon Medi-Physics Co Ltd, Tokyo, Japan). The results of scintigraphy were then compared with previous echocardiography data.Results: Measuring global longitudinal strain (GLS) was impossible in 51% of patients. Measuring left ventricular ejection fraction (LVEF) was impossible in 15% of patients. A significant reduction of 123I-BMIPP uptake was observed in 15 patients out of 55 patients (27.3%). Among the 51 patients who were not previously diagnosed with CTRCD, 11 patients (21.6%) showed a significant reduction of 123I-BMIPP uptake.Conclusion: Myocardial scintigraphy with 123I-BMIPP detected myocardial damage in asymptomatic patients. If echocardiography is difficult to perform, myocardial scintigraphy could provide a second option for evaluating CTRCD.

C41 AN UNUSUAL CASE OF “PULMONARY EMBOLISM”

Abstract Background Pulmonary vein stenosis (PVS) is a complication of catheter–based radiofrequency ablation (RFA) for atrial fibrillation (AF), caused by a vascular response which leads to replacement of necrotic myocardium with collagen. Clinical presentation can mimic pulmonary embolism (PE) and usually appears some months after procedure. Case report A 65–year–old man was hospitalized in March 2021 with a complaint of worsening dyspnoea on exertion, over the course of one month. He had a past medical history of persistent atrial fibrillation, because of which he underwent four pulmonary vein ablations (both RFA and crioablation), the last one in 2019. The previous echocardiogram showed a high systolic pulmonary arterial pressure (sPAP of 75 + 5 mmHg) with normal right ventricular function and dimensions. Despite D–dimer at admission was negative, a CT pulmonary angiography was performed and showed occlusion of left superior pulmonary vein and a severe stenosis of right superior pulmonary vein; ventilation–perfusion scintigraphy (V/Q scan) demonstrated widespread decreased perfusion of both superior lung lobes. The patient underwent angioplasty of right pulmonary vein and after the procedure sPAP greatly decreased (35 mmHg). Discussion Despite its reduction in incidence and its short–term presentation from procedure, severe symptomatic pulmonary vein stenosis must be considered among complications of ablation for atrial fibrillation. Delayed symptoms can also present years after procedure, even if in literature few similar cases are described. Ventilation–perfusion scintigraphy is a very sensible method to assess the functional significance of pulmonary vein stenosis and it also relates with symptoms’ severity. It should be performed in case of a high clinical suspicion, considering that the characteristic ventilation–perfusion mismatch of this condition can be seen in other diseases too, over all pulmonary embolism. Conclusions This case report emphasizes the importance of a thorough anamnesis and an exact interpretation of diagnostic imaging to correctly identify this AF ablation complication and optimize the patient’s therapeutic management. It must be considered that PV stenosis can develop late and with unusual symptoms, mimicking other diseases, like pulmonary embolism, which has the same scintigraphic imaging.

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

BackgroundTransthyretin 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.ResultsOur 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.ConclusionAutomated 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.