Planar Scintigraphy Research Articles

Quantitative assessment of kidney split function and mean transit time in healthy patients using dynamic 18F-FDG PET/MRI studies with denoising and deconvolution methods making use of Legendre polynomials

PurposeOur objective was to assess a deconvolution and denoising technique based on Legendre polynomials compared to matrix deconvolution on dynamic 18F-FDG renography of healthy patients.MethodThe study was carried out and compared to the data of 24 healthy patients from a published study who underwent examinations with 99mTc-MAG3 planar scintigraphy and 18F-FDG PET/MRI. Due to corruption issues in some data used in the published article, post-publication measurements were provided. We have been warned that post-publication data were treated differently. The smoothing method switched from Bezier to Savitzky–Golay and the deconvolution from matrix-based (with Tikhonov Regularization) to Richardson–Lucy. A comparison of the split function and mean transit times of the published and post-publication data against our method based on Legendre polynomials was performed.ResultsFor split function, we only observed a good agreement between the processing methods for the 99mTc-MAG3 and the post-published data. No correlation was found between the split functions obtained on the 99mTc-MAG3 and the 18F-FDG, contrary to the published study. However, all calculated split function values for 18F-FDG and 99mTc-MAG3 were within the established normal range. For the mean transit time, the correlation was moderate with published data and very good with the post-publication measurements for both 99mTc-MAG3 and 18F-FDG. Bias of the Bland–Altman analysis of the mean transit times for 99mTc-MAG3 versus 18F-FDG was 1.1 min (SD 1.7 min) for the published data, − 0.11 min (SD 1.9 min) for the post-publication results and .05 min (SD 1.9 min) for our method.ConclusionsThe processing methods used in the original publication and in the post-publication work were quite complex and required adaptation of the fitting parameters for each individual and each type of examination. Our method did not require any specific adjustment; the same unmodified and fully automated algorithm was successfully applied to all data.

Preoperative visualization of parathyroid pathology in patients with primary hyperparathyroidism using PAT/KT: a retrospective study

INTRODUCTION: Topical diagnosis of pathologically altered parathyroid glands in patients with primary hyperparathyroidism is a challenge both for specialists of radial diagnostics and for planning the scope of surgical intervention. The choice of diagnostic modality for localization of parathyroid glands depends on the availability of the method for a particular medical center. PET/CT is a promising method to determine the localization of parathyroid adenomaOBJECTIVE: To analyze the experience of using PET/CT with 11C-methionine and PET/CT with 11C-choline for preoperative diagnosis of parathyroid pathology in patients with primary hyperparathyroidism.MATERIALS AND METHODS: 72 patients diagnosed with PHPT and underwent surgical treatment were included in the study. Before surgical intervention all patients underwent laboratory and instrumental investigations in the scope of: blood tests for PTH, TTH, ionized calcium, calcitonin, 25(OH)D, creatinine, phosphorus, ultrasound of the neck, computer tomography of the neck with intravenous bolus contrasting.RESULTS: PET/CT showed the highest rates of DA in the patient group before primary surgery — 90.9%, compared with ultrasound (89.6%) and CT with IV contrast (84.9%). In the group of solitary adenomas of ectopic MTCS, PET/CT also had a higher DA — 92.8% than the other modalities. In patients with relapsed or persistent disease, the informativity rates of CT with intravenous contrast and PET/CT were similar (Se — 100%, Sp — 94.1%, DT — 96.2%).DISCUSSION: The algorithm for preoperative evaluation of patients to identify the location of pathologic parathyroid glands now includes imaging with two modalities: Neck ultrasound and radionuclide imaging: planar scintigraphy (washout/subtraction), SPECT, SPECT-CT. If the results are questionable, a CT scan of the neck with contrast or PET/CT is performed as a second step. None of the modalities has 100% diagnostic accuracy. Our study demonstrated the superiority of PET/CT over ultrasound and CT w/in contrast in a group of patients scheduled for primary surgical treatment. In a small group of patients, high informative rates of PET/CT and CT with contrast were demonstrated before reoperation, confirming the great potential of these techniques in these patients.CONCLUSION: PET/CT with 11C-methionine and PET/CT with 11C-choline have high diagnostic accuracy in patients with primary hyperparathyroidism before reoperation. PET/CT and CT with contrast showed similarly high diagnostic accuracy for the diagnosis of parathyroid adenoma with persistence or recurrence of the disease in patients with primary hyperparathyroidism.

Deep learning model using planar whole-body bone scintigraphy for diagnosis of skull base invasion in patients with nasopharyngeal carcinoma

PurposeThis study assesses the reliability of deep learning models based on planar whole-body bone scintigraphy for diagnosing Skull base invasion (SBI) in nasopharyngeal carcinoma (NPC) patients.MethodsIn this multicenter study, a deep learning model was developed using data from one center with a 7:3 allocation to training and internal test sets, to diagnose SBI in patients newly diagnosed with NPC using planar whole-body bone scintigraphy. Patients were diagnosed based on a composite reference standard incorporating radiologic and follow-up data. Ten different convolutional neural network (CNN) models were applied to both whole-image and partial-image input modes to determine the optimal model for each analysis. Model performance was assessed using the area under the receiver operating characteristic curve (AUC), calibration, decision curve analysis (DCA), and compared with expert assessments by two nuclear medicine physicians.ResultsThe best-performing model using partial-body input achieved AUCs of 0.80 (95% CI: 0.73, 0.86) in the internal test set, 0.84 (95% CI: 0.77, 0.91) in the external cohort, and 0.78 (95% CI: 0.73, 0.83) in the treatment test cohort. Calibration curves and DCA confirmed the models’ excellent discrimination, calibration, and potential clinical utility across internal and external datasets. The AUCs of both nuclear medicine physicians were lower than those of the best-performing deep learning model in external test set (AUC: 0.75 vs. 0.77 vs. 0.84).ConclusionDeep learning models utilizing partial-body input from planar whole-body bone scintigraphy demonstrate high discriminatory power for diagnosing SBI in NPC patients, surpassing experienced nuclear medicine physicians.

Role of quantitative planar lung perfusion scintigraphy and tomography in identifying target lobes in patients with emphysematous phenotype of advanced chronic obstructive pulmonary disease: a retrospective cross-sectional study.

Chronic obstructive pulmonary disease (COPD) is a common, preventable, and treatable disease. Despite optimal medical therapy and pulmonary rehabilitation, bronchoscopic and surgical lung volume reduction may still be necessary. Identifying the target lobe is crucial for the success of these treatments. This study aims to compare the role of quantitative planar lung perfusion scintigraphy (QPLPS) with quantitative lung computed tomography (StratX®), which is used in identifying the target lobe before the Zephyr® endobronchial valve (EBV) placement in patients with the emphysematous phenotype of advanced COPD. A single-center retrospective cross-sectional study was performed in the Department of Pulmonology at the University of Health Sciences Turkey, Yedikule Chest Diseases and Thoracic Surgery Education and Research Hospital between June 2019 and June 2022. The study included 46 patients with the emphysematous phenotype of advanced COPD, who were all candidates for Zephyr® EBV therapy. The target lobes were assessed using the QPLPS and StratX® and the agreement between the methods was analyzed by the Kappa statistic method. Additionally, demographic characteristics, respiratory function tests, distributions of emphysema, and 6-minute walk test results of patients were recorded. The median age was 67 (42-80) years and 42 (91.3%) were male. In QPLPS, the perfusion percentages were 7.47%±3.31%, 9.59%±2.67%, and 13.32%±2.59% for the 1st, 2nd and 3rd target lobes, respectively while in StratX®, the voxel densities were 68.28%±9.16%, 63.79%±7.42%, and 60.69%±5.35%. In StratX®, the fissure integrity (FI) at the target lobe was 76.25%±21.18%, 84.68%±17.67%, and 86.19%±13.19%, respectively. There was a significant agreement between the methods in identifying the first, second, and third target lobes in all patients (Kappa coefficient: 0.897, 0.700, and 0.522), and also in identifying the first and second target lobes in patients with heterogeneous (Kappa coefficient: 0.879, and 0.735), and homogeneous subgroups (Kappa coefficient: 0.919, and 0.672). There is an agreement between QPLPS and StratX® in identifying the target lobe in patients with severe emphysema, including those with homogeneous diseases. However, StratX® may be preferred, considering that it also predicts FI.

99mTc]Tc-hydroxydiphosphonate uptake in soft tissue is associated with amyloid load in subcutaneous abdominal fat tissue and mortality in wild-type transthyretin amyloidosis patients.

Bone scintigraphy is key to non-invasively diagnosing wild-type transthyretin (ATTRwt) amyloidosis, and is mainly used to assess cardiac radiotracer uptake. However, extracardiac radiotracer uptake is also observed. We investigated whether intensity of soft tissue radiotracer uptake is associated with amyloid load in subcutaneous abdominal fat tissue and with mortality. This prospective cohort study included 94 ATTRwt amyloidosis patients and 26 amyloid-negative heart failure controls who underwent whole-body [99mTc]Tc-hydroxydiphosphonate scintigraphy. Site-to-background ratios were calculated for heart, elbows, subcutaneous tissue, shoulders and wrists on anterior planar bone scintigraphy images using rib and whole-body radiotracer uptake as background. Fat tissue aspirates were stained with Congo red to grade amyloid load. Site-to-rib ratios were compared between ATTRwt amyloidosis patients and controls, and associations of site-to-background ratio with Congo red score and all-cause mortality were studied. ATTRwt amyloidosis patients had higher soft tissue-to-rib, heart-to-rib and heart-to-whole body ratios compared with controls. The intensity of soft tissue uptake was positively associated with amyloid load in fat tissue in ATTRwt amyloidosis patients. Estimated glomerular filtration rate, N-terminal brain natriuretic propeptide, high-sensitivity cardiac troponin T (hs-cTnT), and the prognostic Mayo and NAC staging system were associated with all-cause mortality in univariable models. Soft tissue/rib ratio, hs-cTnT and the prognostic staging systems were the only two variables that were independently associated withall-cause mortality. Soft tissue radiotracer uptake on bone scintigraphy in ATTRwt amyloidosis patients is positively associated with amyloid load in abdominal fat tissue and is independently associated with mortality.

Pulmonary perfusion in long-term survivors of COVID-19-related severe acute respiratory distress syndrome treated by extracorporeal membrane oxygenation.

COVID-19associates with a hypercoagulant state and an increased risk for venous thromboembolic events (VTEs). Whether severe COVID-19 infection requiringextracorporeal membrane oxygenation(ECMO) support might lead to chronic pulmonary perfusion abnormalities and chronic thromboembolic pulmonary disease/hypertension remains unclear. The purpose of this study was to evaluate chronic pulmonary perfusion abnormalities in long-term survivors of COVID-19-related severe acute respiratory distress syndrome (ARDS) treated by ECMOat our institution. Pulmonary perfusion was examined by ventilation/perfusion(V/Q) single-photon emission computed tomographyor V/Q planar scintigraphy at least 3 months after ECMO explantation, comorbidities and incidence of thromboembolic events were recorded as well. Of 172 COVID-19 patients treated by ECMO for severe COVID-19 pneumonia between March 2020 and November 2021, only 80 were successfully weaned from ECMO. Of those, 37 patients were enrolled into the present analysis (27% female, mean age 52 years). Median duration of ECMO support was 12 days. In 24 (65%) patients VTE was recorded in the acute phase (23 patients developed ECMO cannula-related deep vein thrombosis, 5 of them had also a pulmonary embolism, and one thrombus was associated with a central catheter). The median duration between ECMO explantation and assessment of pulmonary perfusion was 420 days. No segmental or larger mismatched perfusion defects were then detected in any patient. In conclusion, in long-term survivors of COVID-19-related ARDS treated by ECMO, no persistent pulmonary perfusion abnormalities were detected although VTE was common.

Dual-tracer subtraction scintigraphy combined with SPECT/CT in preoperative patients with primary hyperparathyroidism.

Abstract.

SPECT/CT in the Diagnosis of Ectopic Gastric Mucosa-Meckel's Diverticulum.

Aim The imaging of Meckel's diverticulum (MD) is based of accumulation of Tc-99m pertechnetate in the ectopic gastric mucosa (EGM) content. Although the diagnostic accuracy of this imaging modality is high, there are some overlap patients with coexisting gastrointestinal bleeding and false positive causes hampering diagnostic power. The aim of this study was to evaluate the possible contribution of single-photon emission computed tomography/computed tomography (SPECT/CT) in EGM-MD diagnosis and to determine the indication of this additional imaging modality. Materials and Methods Fifty-two pediatric patients (24 girls, 28 boys; mean age: 8.06 ± 5.22 years old) who have suspicion of MD and referred for scintigraphy were evaluated retrospectively. Additional SPECT/CT were performed to selected five cases among the group. The results of the scintigraphy as well as SPECT/CT were compared with endoscopy, pathology, and/or follow-up results. Results There were 9 patients with equivocal study results, 12 positive results, and the others were considered negative MD scintigraphy. One patient was out of follow-up and 10 patients underwent surgery. Only one single patient was negative during surgery but scintigraphy was also negative. The diagnostic sensitivity, specificity, and accuracy were 100, 95, and 96%, respectively. Among five patients with SPECT/CT results one patient was diagnosed by only SPECT/CT who had EGM in duplication cyst, one equivocal patient was diagnosed as descending colon bleeding, and one patient's lesion was clearly delineated by SPECT/CT. Conclusion SPECT/CT has clear advantage over standard planar scintigraphy imaging in EGM-MD determination. This modality might decrease equivocal and false positive results but this issue has to be addressed with further studies.

Comparison of novel PSMA-targeting [177Lu]Lu-P17-087 with its albumin binding derivative [177Lu]Lu-P17-088 in metastatic castration-resistant prostate cancer patients: a first-in-human study.

Prostate-specific membrane antigen (PSMA) is a promising target for diagnosis and radioligand therapy (RLT) of prostate cancer. Two novel PSMA-targeting radionuclide therapy agents, [177Lu]Lu-P17-087, and its albumin binder modified derivative, [177Lu]Lu-P17-088, were evaluated in metastatic castration-resistant prostate cancer (mCRPC) patients. The primary endpoint was dosimetry evaluation, the second endpoint was radiation toxicity assessment (CTCAE 5.0) and PSA response (PCWG3). Patients with PSMA-positive tumors were enrolled after [68Ga]Ga-PSMA-11 PET/CT scan. Five mCRPC patients received [177Lu]Lu-P17-087 and four other patients received [177Lu]Lu-P17-088 (1.2 GBq/patient). Multiple whole body planar scintigraphy was performed at 1.5, 4, 24, 48, 72, 120 and 168h after injection and one SPECT/CT imaging was performed at 24h post-injection for each patient. Dosimetry evaluation was compared in both patient groups. Patients showed no major clinical side-effects under this low dose treatment. As expected [177Lu]Lu-P17-088 with longer blood circulation (due to its albumin binding) exhibited higher effective doses than [177Lu]Lu-P17-087 (0.151 ± 0.036 vs. 0.056 ± 0.019 mGy/MBq, P = 0.001). Similarly, red marrow received 0.119 ± 0.068 and 0.048 ± 0.020 mGy/MBq, while kidney doses were 0.119 ± 0.068 and 0.046 ± 0.022 mGy/MBq, respectively. [177Lu]Lu-P17-087 demonstrated excellent tumor uptake and faster kinetics; while [177Lu]Lu-P17-088 displayed a slower washout and higher average dose (7.75 ± 4.18 vs. 4.72 ± 2.29 mGy/MBq, P = 0.018). After administration of [177Lu]Lu-P17-087 and [177Lu]Lu-P17-088, 3/5 and 3/4 patients showed reducing PSA values, respectively. [177Lu]Lu-P17-088 and [177Lu]Lu-P17-087 displayed different pharmacokinetics but excellent PSMA-targeting dose delivery in mCRPC patients. These two agents are promising RLT agents for personalized treatment of mCRPC. Further studies with increased dose and frequency of RLT are warranted to evaluate the potential therapeutic efficacy. 177Lu-P17-087/177Lu-P17-088 in Patients with Metastatic Castration-resistant Prostate Cancer (NCT05603559, Registered at 25 October, 2022). URL OF REGISTRY: https://classic. gov/ct2/show/NCT05603559 .

3-[18F]Fluoro-para-hydroxyphenethylguanidine (3-[18F]pHPG) PET-A Novel Imaging Modality for Paraganglioma.

Functional positron emission tomography (PET) imaging for the characterization of pheochromocytoma and paraganglioma (PCC/PGL) and for detection of metastases in malignant disease, offers valuable clinical insights that can significantly guide patient treatment. This work aimed to evaluate a novel PET radiotracer, 3-[18F]fluoro-para-hydroxyphenethylguanidine (3-[18F]pHPG), a norepinephrine analogue, for its ability to localize PCC/PGL. 3-[18F]pHPG PET/CT whole-body scans were performed on 16 patients (8 male:8 female; mean age 47.6 ± 17.6 years; range, 19-74 years) with pathologically confirmed or clinically diagnosed PCC/PGL. After intravenous administration of 304 to 475 MBq (8.2-12.8 mCi) of 3-[18F]pHPG, whole-body PET scans were performed at 90 minutes in all patients. 3-[18F]pHPG PET was interpreted for abnormal findings consistent with primary tumor or metastasis, and biodistribution in normal organs recorded. Standardized uptake value (SUV) measurements were obtained for target lesions and physiological organ distributions. 3-[18F]pHPG PET showed high radiotracer uptake and trapping in primary tumors, and metastatic tumor lesions that included bone, lymph nodes, and other solid organ sites. Physiological biodistribution was universally present in salivary glands (parotid, submandibular, sublingual), thyroid, heart, liver, adrenals, kidneys, and bladder. Comparison [68Ga]DOTATATE PET/CT was available in 10 patients and in all cases showed concordant distribution. Comparison [123I]meta-iodobenzylguanidine [123I]mIBG planar scintigraphy and SPECT/CT scans were available for 4 patients, with 3-[18F]pHPG showing a greater number of metastatic lesions. We found the kinetic profile of 3-[18F]pHPG PET affords high activity retention within benign and metastatic PCC/PGL. Therefore, 3-[18F]pHPG PET imaging provides a novel modality for functional imaging and staging of malignant paraganglioma with advantages of high lesion affinity, whole-body coregistered computed tomography, and rapid same-day imaging.

Возможности создания источников излучения для персонализированной брахитерапии на основе 3D-каркасов из сплава титана

Purpose: The study explores the possibility of manufacturing radiation sources for personalized brachytherapy using titanium alloys, activated in a neutron flux reactor, by measuring the radiation composition of applicator implants and their dosimetric characteristics. Material and methods: A 3D implant of a brachytherapy source was made from a titanium alloy using an additive selective laser melting setup. The titanium 3D prototype was irradiated for three days in the horizontal experimental channel of the IR-8 reactor. Subsequently, measurements of the gamma-ray spectrum from the irradiated implant were carried out on a spectrometer, and dose characteristics of the 3D implant were measured using a dosimeter-radiometer. Results: In the experimental 3D implant obtained by us, the radionuclide 47Sc exhibits the highest activity. Currently, 47Sc is considered a promising candidate for brachytherapy. It possesses attractive nuclear and physical properties as a β-emitter, decaying into the ground state (27 %) of 47Ti (Eβmax = 600 keV) and the excited state of 47Ti (Eβmax = 439 keV) with a half-life of 3.4 days. Additionally, 47Sc emits γ-radiation at an energy of 159 keV (68 %), which is suitable for imaging, allowing for SPECT or planar scintigraphy and obtaining a picture of the drug’s distribution in the body. In the experimental implant, small amounts of scandium radionuclides – 46Sc and 48Sc, were also detected, emitting sufficiently hard gamma radiation, which can pose a problem for patient dosage determination. The advantages of using titanium-47 with an enrichment of over 95 %, economically available, have been demonstrated, allowing for high radiochemical yields of 47Sc, sufficient for therapy. Conclusion: The 3D printing technology allows the production of a customized applicator for brachytherapy of specific dimensions and the delivery of arbitrarily-shaped sources to the tumor area for personalized therapy of oncological diseases. When implanting sources based on titanium alloys activated in a neutron flux of a research nuclear reactor, the radionuclide scandium-47 exhibits the highest activity.

Sodium iodide symporter immunolabelling as a predictor of clinical iodide uptake in canine thyroid carcinoma: A preliminary study.

Thyroid follicular tumours may take up iodide via the sodium-iodide symporter. Knowledge of iodide uptake could then allow treatment with I-131 in dogs with high-risk tumours. The objective of this study was to determine the relationship between clinically detectable iodide uptake (as determined by scintigraphy and/or thyroxine concentrations) and sodium iodide symporter immunohistochemical labelling on histologically fixed thyroid tumours. Nineteen dogs were identified who were diagnosed with thyroid carcinoma and underwent surgery from November 2017 to July 2021. All had recorded thyroid hormone concentrations and were hyperthyroid and/or underwent preoperative nuclear imaging using planar scintigraphy (technetium-99m or I-123), or I-124 PET-CT. All dogs subsequently underwent surgery to remove the thyroid mass. Twenty-two tumours were submitted for histopathologic analysis immediately following surgery, which confirmed a diagnosis of thyroid carcinoma for each tumour. Images and/or thyroid hormone concentrations were reviewed for the included cases, and tumours were sorted into an avid/functional group (group 1) and a non-avid/functional group (group 2). The tumour tissues were re-examined histologically using sodium iodide symporter (NIS) immunohistochemistry (IHC). Group 1 contained 15 avid/functional tumours. Twelve of these tumours had membranous NIS IHC labelling. Group 2 contained 7 non-avid tumours. One of these tumours had membranous NIS IHC labelling. This resulted in an overall sensitivity and specificity for identification of avid/functional tumours with membranous NIS of 80.0% and 85.7%, respectively. NIS IHC may predict ion trapping in canine follicular thyroid tumours. Further studies using iodide-based imaging are warranted to better determine the clinical utility of this diagnostic modality.

Diagnostic Performance of Perfusion-Only SPECT/CT for Chronic Thromboembolic Pulmonary Hypertension in Comparison With Ventilation-Perfusion Planar, SPECT, and SPECT/CT Imaging.

The aim of this study was to assess the diagnostic performance of perfusion-only SPECT/CT (Q SPECT/CT) in comparison with that of ventilation/perfusion planar scintigraphy (V/Q planar), perfusion SPECT with ventilation scan (V/Q SPECT), and perfusion SPECT/CT with ventilation scan (V/Q SPECT/CT) in chronic thromboembolic pulmonary hypertension (CTEPH). Patients with pulmonary hypertension who underwent ventilation-perfusion planar and SPECT/CT were retrospectively recruited. Two nuclear medicine physicians interpreted V/Q planar, V/Q SPECT, V/Q SPECT/CT, and Q SPECT/CT according to the European Association of Nuclear Medicine criteria. The diagnostic accuracy of these modalities for CTEPH was compared using a composite reference standard of pulmonary angiography, imaging test, cardiorespiratory assessment, and follow-up. A total of 192 patients were enrolled, including 85 with CTEPH. The sensitivity of Q SPECT/CT was 98.8%, which similar to that of V/Q planar (97.6%), V/Q SPECT (96.5%), or V/Q SPECT/CT (100.0%). In contrast, Q SPECT/CT exhibited significantly lower specificity (73.8%) compared with V/Q planar (86.9%, P = 0.001), V/Q SPECT (87.9%, P < 0.001), and V/Q SPECT/CT (88.8%, P < 0.001). The significantly lower specificity of Q SPECT/CT, compared with the 3 others, was observed in the subgroup aged ≥50 years ( P < 0.001 for all), but not in those <50 years. Q SPECT/CT exhibited lower specificity compared with V/Q planar, V/Q SPECT, and V/Q SPECT/CT in diagnosing CTEPH. It might underscore the essential role of a ventilation scan in patients with PH, even with the introduction of SPECT/CT.

Extravasation After [ 177 Lu]Lu-HA-DOTATATE Therapy.

Extravasation of the radiopharmaceutical during peptide receptor radionuclide therapy infusion is an unwanted infrequently reported event. We present the case of a 74-year old woman with a neuroendocrine tumor who was referred for peptide receptor radionuclide therapy. During intravenous infusion of 7.4 GBq [ 177 Lu]Lu-HA-DOTATATE in the upper right arm, extravasation of the radiopharmaceutical occurred through a displaced intravenous catheter. Planar scintigraphy showed pooling of radioactivity in the right upper arm. After 24 hours, the swelling in the arm was decreased; however, erythema was increased. One week later, symptoms had disappeared, and the patient did not experience any complications during follow-up of 11 months.

PET/CT and SPECT/CT imaging of 90Y hepatic radioembolization at therapeutic and diagnostic activity levels: Anthropomorphic phantom study.

Prior to 90Y radioembolization procedure, a pretherapy simulation using 99mTc-MAA is performed. Alternatively, a small dosage of 90Y microspheres could be used. We aimed to assess the accuracy of lung shunt fraction (LSF) estimation in both high activity 90Y posttreatment and pretreatment scans with isotope activity of ~100 MBq, using different imaging techniques. Additionally, we assessed the feasibility of visualising hot and cold hepatic tumours in PET/CT and Bremsstrahlung SPECT/CT images. Anthropomorphic phantom including liver (with two spherical tumours) and lung inserts was filled with 90Y chloride to simulate an LSF of 9.8%. The total initial activity in the liver was 1451 MBq, including 19.4 MBq in the hot sphere. Nine measurement sessions including PET/CT, SPECT/CT, and planar images were acquired at activities in the whole phantom ranging from 1618 MBq down to 43 MBq. The visibility of the tumours was appraised based on independent observers' scores. Quantitatively, contrast-to-noise ratio (CNR) was calculated for both spheres in all images. LSF estimation. For high activity in the phantom, PET reconstructions slightly underestimated the LSF; absolute difference was <1.5pp (percent point). For activity <100 MBq, the LSF was overestimated. Both SPECT and planar scintigraphy overestimated the LSF for all activities. Lesion visibility. For SPECT/CT, the cold tumour proved too small to be discernible (CNR <0.5) regardless of the 90Y activity in the liver, while hot sphere was visible for activity >200 MBq (CNR>4). For PET/CT, the cold tumour was only visible with the highest 90Y activity (CNR>4), whereas the hot one was seen for activity >100 MBq (CNR>5). PET/CT may accurately estimate the LSF in a 90Y posttreatment procedure. However, at low activities of about 100 MBq it seems to provide unreliable estimations. PET imaging provided better visualisation of both hot and cold tumours.

Optimisation of the bone single photon emission computed tomography in oncology patients

Introduction: The introduction of hybrid imaging systems such as Single Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) has completely changed the scanning procedure of conventional diagnostic nuclear medicine protocols. Modern bone scintigraphy protocols include SUV quanitification and Whole Body (WB) SPECT/CT scanning modality. The major limitation of these new technologies is relatively long scanning time. New detector systems with modern reconstruction softwares have been developed for fast scanning SPECT protocolos. These new technologies can produce images of reduced acquisition with same quality as full scanning acquisition. As a result new studies suggest that planar WB scintigraphy should be replaced with WB SPECT/CT. Methods: One hundred oncology patients performed SPECT/CT as a part as their clinical follow-up. Three different scanning and three reconstruction protocols have been evaluated. Two nuclear medicine physicians evaluated with Likert scale image sharpness, lesion visibility, and lesion background detectability. The overall image quality was determined as the sum of these three parameters. Results: In terms of scan duration reduction on image quality, Volumetrix Evolution for Bone performed during ultra-fast SPECT acquisition achieved the highest score, which is superior compared to the standard SPECT acquisition protocol. The overall image quality was the best with the Volumetrix MI Evolution for Bone protocol for ultra-fast acquisition Conclusion: The Evolution for Bone protocol for ultra-fast acquisition showed best results compared to other protocols. The adoption of new acquisition SPECT protocol may offer more comfortable exams, resulting in higher patient satisfaction. The implementation of this new protocol can lead to an improvement in SPECT sensitivity, primarily due to the reduction of SPECT motion artifacts.

Preoperative diagnosis of parathyroid gland pathology in patients with persistent or recurrent primary hyperparathyroidism: a retrospective study

INTRODUCTION: Localization of abnormal parathyroid glands in persistent or relapsed patients with primary hyperparathyroidism presents problems for surgeons before repeated surgery. There is no clear standard for the choice of diagnostic modality for localization of PG in this group of patients.OBJECTIVE: To search for the optimal diagnostic protocol of the parathyroid pathology preoperative diagnosis in patients with primary hyperparathyroidism with persistent or recurrent disease.MATERIALS AND METHODS: 55 patients diagnosed with persistence or recurrence of PHPT who underwent repeated surgical treatment were included in the study. Before surgical intervention all patients underwent laboratory and instrumental investigations in the volume of: blood tests for PTH, TTH, ionized calcium, 25(OH)D, creatinine, phosphorus, neck ultrasound, parathyroid scintigraphy by washout method, dual-isotope subtractive scintigraphy of parathyroid glands (early and delayed phases), SPECT of parathyroid glands (with uptake correction), computed tomography of the neck with intravenous bolus contrast.RESULTS: CT and planar subtraction dual-isotope scintigraphy showed the highest DA in the overall group (persistence and recurrence) (78% and 78%), with the DA of these methods differing slightly (88% and 92%) and overall accuracy being higher for CT (90% and 87%). Neck ultrasound showed the lowest rates among all methods (DA — 46%, DS — 80%, OA — 67%). Planar scintigraphy (washout) and SPECT were comparable in their informativeness: DA — 67% and 65%, DS — 96% and 98%, OA — 85% and 86%.DISCUSSION: The most commonly used current diagnostic search algorithm before reoperation is visualization of the thyroid gland by two modalities: Neck ultrasound and parathyroid scintigraphy (washout/subtraction) or SPECT-CT. In doubtful cases, the second step is computed tomography of the neck with contrast or PET/CT. It is extremely difficult to choose one optimal diagnostic method, as none of them has 100% diagnostic accuracy. In addition, each study has limitations, and the availability of some modalities is limited. In our study, the location of pathologically altered thyroid was correctly recognized in 90% of cases by CT with contrast and in 87% of cases by planar subtraction dual-isotope scintigraphy. The informativeness of neck ultrasound showed the lowest values of all modalities. SPECT and planar washout scintigraphy took an intermediate position in terms of diagnostic accuracy.CONCLUSION: Isolated ultrasonography of the neck has low diagnostic accuracy in patients with primary hyperparathyroidism with persistent or recurrent disease. We recommend the combination of US with contrast-enhanced computed tomography of the neck or US with dual isotope subtraction scintigraphy of the parathyroid glands, which have the same diagnostic accuracy. SPECT and planar washout scintigraphy can be used for the diagnosis of abnormal parathyroid glands in persistent or recurrent patients with primary hyperparathyroidism when more informative techniques are unavailable. When the techniques were combined, the combination of ultrasound/CT with contrast and ultrasound/planar subtraction dual isotope scintigraphy showed the best results with DA of 85% and 86%.

Verification of reprojected planar images generated from a ring-configured cadmium zinc telluride gamma camera in scintigraphy for diagnosing transthyretin cardiac amyloidosis.

Non-invasive diagnosis of amyloid transthyretin (ATTR) cardiac amyloidosis using planar scintigraphy and single-photon emission computed tomography-computed tomography (SPECT-CT) with [99mTc]Tc-3,3-diphosphono-1,2-propanodicarboxylic acid ([99mTc]Tc-DPD) has high specificity and sensitivity. However, the introduction of ring-configured cadmium zinc telluride (CZT) gamma cameras warrants an update in the acquisition method since these systems are not able to perform planar scintigraphy. We aimed to verify the use of reprojected planar images from SPECT-CT as a replacement for planar scintigraphy in evaluating ATTR-amyloidosis. The study examined 30 patients referred for clinically indicated [99mTc]Tc-DPD scintigraphy who were scanned with both a conventional gamma camera and a ring-configured CZT gamma camera. Planar scintigraphy from the conventional gamma camera was compared with reprojected planar images from the ring-configured CZT gamma camera. The images were evaluated in regard to image quality and Perugini visual score in a blinded fashion by three nuclear medicine physicians. Heart-to-contralateral (H/CL) ratios were calculated. There were 27 patients who had an identical Perugini score in planar and reprojected planar images, yielding a strong level of agreement and inter-rater reliability among the three readers. The H/CL ratios showed a strong correlation ratio (r = 0.98, P < 0.0001). A shift towards lower image quality was seen for the reprojected images. Reprojected planar images generated from a ring-configured CZT gamma camera combined with SPECT-CT can be used to score ATTR amyloidosis and extract H/CL ratios in the same way as planar images and SPECT-CT from a conventional gamma camera.

Improvement of Whole-body Bone Planar Images on a Bone-dedicated Single-photon Emission Computed Tomography Scanner by Blind Deconvolution Algorithm.

We have developed a bone-dedicated collimator with higher sensitivity but slightly degraded resolution on single-photon emission computed tomography (SPECT) for planar bone scintigraphy, compared with conventional low-energy high-resolution collimator. In this work, we investigated the feasibility of using the blind deconvolution algorithm to improve the resolution of planar images on bone scintigraphy. Monte Carlo simulation was performed with the NCAT phantom for modeling bone scintigraphy on the clinical dual-head SPECT scanner (Imagine NET 632, Beijing Novel Medical Equipment Ltd.) equipped with the bone-dedicated collimator. Maximum likelihood estimation method was used for the blind deconvolution algorithm. The initial estimation of point spread function (PSF) and iteration number for the method were determined by comparing the deblurred images obtained from different input parameters. We simulated different tumors in five different locations and with five different diameters to evaluate the robustness of the initial inputs. Furthermore, we performed chest phantom studies on the clinical SPECT scanner. The quantified increased contrast ratio (CR) between the tumor and the background was evaluated. The 2 mm PSF kernel and 10 iterations provided a practical and robust deblurred image on our system. Those two inputs can generate robust deblurred images in terms of the tumor location and size with an average increased CR of 21.6%. The phantom studies also demonstrated the ability of blind deconvolution, using those two inputs, with increased CRs of 17%, 17%, 22%, 20%, and 13% for lesions with diameters of 1 cm, 2 cm, 3 cm, 4 cm, and 5 cm, respectively. It is feasible to use the blind deconvolution algorithm to deblur the planar images for SPECT bone scintigraphy. The appropriate values of the PSF kernel and the iteration number for the blind deconvolution can be determined using simulation studies.

Comparative Analysis of Diagnostic Efficacy in Primary Hyperparathyroidism: A Comparison Analysis of 11C-Choline PET/CT, Neck Ultrasonography, 99mTc-MIBI Dual-Phase Planar Scintigraphy, and 99mTc-MIBI SPECT/CT Imaging.

Objective: To compare the diagnostic efficacy of 11C-choline PET/CT, neck ultrasonography, 99mTc-MIBI dual-phase planar scintigraphy, and 99mTc-MIBI SPECT/CT imaging in the diagnosis of primary hyperparathyroidism (PHPT). Methods: We conducted a retrospective analysis of 32 patients with PHPT who visited the Nuclear Medicine Department of Jilin University China-Japan Union Hospital between January 2019 and December 2022. All patients underwent 11C-choline PET/CT, neck ultrasonography, 99mTc-MIBI dual-phase planar scintigraphy, and 99mTc-MIBI SPECT/CT examinations within two months before surgery. Sensitivity, specificity, positive predictive value, and negative predictive value of each imaging study were compared using postoperative pathology and follow-up results. Diagnostic efficacy was further analyzed using ROC curve analysis. Factors influencing on 99mTc-MIBI imaging were also investigated. Results: A total of 35 lesions were resected in the 32 patients. The diagnostic sensitivity of 11C-choline PET/CT, neck ultrasonography, 99mTc-MIBI dual-phase planar scintigraphy, and 99mTc-MIBI SPECT/CT was 88.2%, 52.9%, 58.8%, and 67.6%, respectively. Specificity was 96.8%, 95.7%, 96.8%, and 95.7%, respectively. Positive predictive values were 90.9%, 81.8%, 86.9%, and 85.2%, respectively, and negative predictive values were 95.7%, 84.9%, 86.7%, and 89.1%, respectively. The areas under the ROC curve (AUC) were 0.925, 0.743, 0.778, and 0.817, respectively. Among them, 11C-choline PET/CT had higher sensitivity and AUC than other imaging studies (p<0.05), while specificity, positive predictive value, and negative predictive value were similar (p>0.05). The positive group in 99mTc-MIBI SPECT/CT imaging had significantly larger lesion diameters than the negative group (P<0.05), while preoperative blood calcium and PTH showed no statistical differences (P>0.05). Conclusion: 11C-choline PET/CT demonstrates superior preoperative diagnostic efficacy for PHPT compared to neck ultrasonography, 99mTc-MIBI dual-phase planar scintigraphy, and 99mTc-MIBI SPECT/CT. Lesion size may be the primary factor affecting the sensitivity of 99mTc-MIBI imaging.