Single-photon Emission Computed Tomography/computed Tomography Research Articles

Visual Scoring of Sacroiliac Joint/Sacrum Ratios of Single-Photon Emission Computed Tomography/Computed Tomography Images Affords High Sensitivity and Negative Predictive Value in Axial Spondyloarthritis.

Spondyloarthritis (SpA) is characterized by inflammatory back pain. Magnetic resonance imaging (MRI) was the earlier gold standard technique for detecting early inflammatory change. We reassessed the diagnostic utility of sacroiliac joint/sacrum (SIS) ratios of single-photon emission computed tomography/computed tomography (SPECT/CT) for identifying sacroiliitis. We aimed to investigate of SPECT/CT in diagnosing SpA using a rheumatologist's visual scoring of SIS ratios assessment. We conducted a single-center, medical records review study of patients with lower back pain who underwent bone SPECT/CT from August 2016 to April 2020. We employed semiquantitative visual bone scoring methods of SIS ratio. The uptake of each sacroiliac joint was compared to that of the sacrum (0-2). A score of 2 for the sacroiliac joint of either side was considered diagnostic of sacroiliitis. Of the 443 patients assessed, 40 had axial SpA (axSpA), 24 being radiographic axSpA and 16 being nonradiographic axSpA. The sensitivity, specificity, and positive and negative predictive values of SIS ratio of SPECT/CT for axSpA were 87.5%, 56.5%, 16.6%, and 97.8%, respectively. In receiver operating curve analysis, MRI better diagnosed axSpA than did SIS ratio of SPECT/CT. Although the diagnostic utility of SIS ratio of SPECT/CT was inferior to MRI, visual scoring of SPECT/CT affords high sensitivity and negative predictive value in axSpA. When MRI is inappropriate for certain patients, SIS ratio of SPECT/CT is an alternative tool for identifying axSpA in real practice.

188 Re-N-DEDC Lipiodol for Treatment of Hepatocellular Carcinoma (HCC)-A Clinical and Prospective Study to Assess In-Vivo Distribution in Patients and Clinical Feasibility of Therapy.

Objective The incidence of inoperable hepatocellular carcinoma (HCC) with/without malignant portal vein thrombosis (PVT) is increasing in India for the last decade; thus, Bhabha Atomic Research Centre (BARC), Mumbai, India, developed diethydithiocarbamate (DEDC), a new transarterial radionuclide therapy (TART) agent. 188 Re-N-DEDC lipiodol is an emerging radiotherapeutic agent for inoperable HCC treatment due to its simple and onsite labeling procedure, cost-effectiveness, and least radiation-induced side effects. This study aimed to evaluate in-vivo biodistribution and clinical feasibility of 188 Re-N-DEDC lipiodol TART in HCC and optimization of labeling procedure to assess post-labeling stability and radiochemical yield of labeled lipiodol with 188 Re-N-DEDC complex. Materials and Methods DEDC kits were obtained as gift from BARC, Mumbai. Therapy was given to 31 HCC patients. Post-therapy planar and single-photon emission computed tomography/computed tomography (SPECT/CT) imaging were performed to see tumor uptake and biodistribution. Clinical feasibility and toxicity were decided by Common Terminology Criteria for Adverse Events version 5.0 (CTCAE v 5.0). Statistical Analysis Descriptive statistics was done for data using SPSS v22. Values was expressed as mean ± standard deviation or median with range. Results Post-therapy planar and SPECT/CT imaging showed radiotracer localization in hepatic lesions. Few patients showed lungs uptake due to hepato-pulmonary shunt (lung shunt < 10%). Maximum clearance was observed through urinary tract with very less elimination through hepatobiliary route due to slow rate of leaching of tracer. No patient showed myelosuppression or any other long-term toxicity over median follow-up of 6 months. Mean overall % radiochemical yield of 188 Re-N-DEDC lipiodol was 86.04 ± 2.35%. The complex 188 Re-N-DEDC was found to be stable at 37°C under sterile condition over a period of 1 hour without any significant change on the % radiochemical purity (90.83 ± 3.24%, 89.78 ± 3.67%, 89.22 ± 3.77% at 0, 0.5, 1 hours, respectively). Conclusion Human biodistribution showed very high retention of radiotracer in hepatic lesions with no long-term toxicity with this therapy. The kit preparation procedure is ideally suited for a busy hospital radio-pharmacy. By this procedure, 188 Re-N-DEDC lipiodol can be prepared in high radiochemical yield within a short time (∼45 minutes). Thus, 188 Re-N-DEDC lipiodol can be considered for TART in advanced and/or intermediate HCC.

Inter-observer variability between readers in detection of bone metastases comparing different modalities; PET/CT, SPECT/CT and planar bone scintigraphy.

To assess the inter-observer variability between readers in the detection of bone metastases for different modalities [planar bone scintigraphy (BS), single photon emission computed tomography/computed tomography (SPECT/CT), and fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) (F-18 FDG PET/CT)]. Patients with known primary tumors referred for metastatic workup either by F-18 FDG PET/CT or conventional planar BS and SPECT/CT were enrolled in this prospective study. The three modalities (BS, SPECT/CT, and PET/CT) were acquired for each patient. Interpretation was done by two independent nuclear medicine physicians separately and blindly; reader 1 (R1) and reader 2 (R2). A three-point subjective scale was used (1 = negative for bone metastases, 2 = equivocal, and 3 = positive). The findings were compared to the final patient status based on clinical and radiological follow-up for at least 6 months. The Kappa test was used to assess the degree of agreement between readers in their interpretation of each modality. A total of 54 patients (39 females and 15 males, ages 26-76; mean: 54.7 ± 12) were eligible for this study. Fair agreement 0.372 between R1 and R2 in interpretation of BS was noticed that improved to 0.847 after addition of SPECT/CT. Perfect agreement was achieved between R1 and R2 while interpreting PET/CT images (kappa = 0.964, P < 0.001). F-18 FDG PET/CT significantly improved the inter-observer variability between readers, allowing for better diagnosis of bone metastases in known cancer patients. Also, it was superior to BS and SPECT/CT in the detection of bone metastases.

Radiological-nuclear medicine hybrid diagnostics with SPECT/CT for chronic foot and ankle diseases : Anew and important diagnostic tool

In contrast to standard methods (sonography, X‑ray, CT(computed tomography), MRI(magnetic resonance imaging), numerous diseases of the foot or ankle can be diagnosed using SPECT/CT (single photon emission computed tomography/computed tomography) with regard to their clinical relevance with high accuracy (up to > 90%). The aim of this review is to provide an up-to-date overview of the importance of SPECT/CT in selected diseases of the foot and ankle. Aliterature search was carried out in the Pubmed database using the following terms: SPECT/CT, SPECT, skeletal scintigraphy, CT, computed tomography, foot and ankle disease, OSG, tarsal root, foot pain. The publications were selected with regard to questions and diagnoses that frequently occur in foot and ankle diagnostics. Furthermore, papers that describe amore precise diagnosis, achange in therapy management or areduction in symptoms due to the use of SPECT/CT were selected. Several studies have shown that afocally increased bone metabolism in osteoarthritis and osteochondral lesions correlates significantly with the development of pain. The presence of symptomatic ossicles such as the os naviculare accessorium typeII and os trigonum can be clearly demonstrated with the help of SPECT/CT and cannot be assigned as the source of the symptoms as accurately with any other imaging method. Bony reactions in the area of coalitions, arthrodesis, osteosynthesis, occult fractures, prostheses and diabetic foot cannot be detected with comparable accuracy using any other imaging method, so that therapy concepts in unclear cases, based only on standard imaging are changed inup to 2/3 of cases by SPECT/CT information. SPECT/CT is useful when there are clinical uncertainties despite standard imaging.

Quantitative application of dual-phase 99mTc-sestamibi SPECT/CT imaging of parathyroid lesions: identification of optimal timing in secondary hyperparathyroidism

PurposeIn this retrospective study, we compared the maximum standardized uptake values (SUVmax) of parathyroid lesions and the target-to-background ratio (TBR) of parathyroid lesions to thyroid tissue in early-phase single-photon emission computed tomography/computed tomography (SPECT/CT) versus delayed-phase SPECT/CT in patients with secondary hyperparathyroidism (SHPT) in order to determine the optimal timing of 99mTc- methoxyisobutylisonitrile (99mTc-MIBI) SPECT/CT imaging.MethodsSeventeen patients with a history of chronic kidney failure stage 5 on hemodialysis, underwent pre-operative parathyroid scintigraphy for detection and localization of parathyroid lesions. Retrospective analysis was conducted for lesions with focal accumulation of 99mTc-MIBI. All patients underwent dual-phase 99mTc-MIBI parathyroid scintigraphy and dual-phase SPECT/CT. SUVmax of parathyroid lesions and thyroid tissues was measured.ResultsMean SUVmax of parathyroid lesions was 4.86 on early-phase and 2.58 on delayed-phase SPECT/CT, respectively. Mean TBR was 1.14 on early phase and 1.48 on delayed-phase SPECT/CT, respectively. Statistically significant differences in SUVmax and TBR between dual-phase SPECT/CT were observed (P < 0.001).ConclusionsDelayed-phase SPECT/CT in SHPT is required because of the better image contrast.

An Australian experience using Tc-PSMA SPECT/CT in the primary diagnosis of prostate cancer and for staging at biochemical recurrence after local therapy.

Technetium 99 prostate-specific membrane antigen(Tc-PSMA) single-photon emission computed tomography/computed tomography (SPECT/CT) has the potential to provide greater accessibility globally thangallium 68(Ga)-PSMA positron emission tomography (PET)/CT but has not been studied as extensively in primary diagnosis, staging, or relapse of prostate cancer (PC). We instituted a novel SPECT/CT reconstruction algorithm using Tc-PSMA and established a database to prospectively accumulate data on all patients referred with PC. This study extracts data on all patients referred over a 3.5-year period with the primary aim of comparing the diagnostic accuracy of Tc-PSMA and multiparametric magnetic resonance imaging (mpMRI) in the primary diagnosis of PC. The secondary aim was to assess the sensitivity of Tc-PSMA in detecting disease with relapse after either radical prostatectomy or primary radiotherapy. A total of 425 men referred for primary staging (PS) of PC and 172 men referred with biochemical relapse (BCR) were evaluated. We evaluated diagnostic accuracy and correlations between Tc-PSMA SPECT/CT, magnetic resonance imaging(MRI), prostate biopsy, prostate-specific antigen (PSA), and age in the PS group and positivity rates at different PSA levels in the BCR group. Taking the biopsy's grade according to the International Society of Urological Pathologyprotocol as a reference, the sensitivity (true positive rate), specificity (true negative rate), accuracy (positive and negative predictive value), and precision (positive predictive value) for Tc-PSMA in the PS group were 99.7%, 83.3%, 99.4%, and 99.7%, respectively. Comparison rates for MRI in this group were 96.4%, 71.4%, 95.7%, and 99.1%. We found moderate correlations between Tc-PSMA uptake in the prostate and biopsy grade, the presence of metastases, and PSA. In BCR, the Tc-PSMA positive rates were 38.9%, 53.2%, 62.5%, and 84.6% at PSA levels of <0.2, 0.2 to <0.5, 0.5 to <1.0, and > 1.0 ng/mL respectively. We have shown that Tc-PSMA SPECT/CT using an enhanced reconstruction algorithm has a diagnostic performance similar to Ga-PSMA PET/CT and mpMRI in an everyday clinical setting. It may have some advantages in cost, sensitivity for primary lesion detection, and the ability for intraoperative localization of lymph nodes.

MP64-08 99m TC- SESTAMIBI SPECT/CT FOR THE CHARACTERIZATION OF SMALL RENAL MASSES: INITIAL EXPERIENCE FROM a TERTIARY REFERRAL CENTER

MP64-08 ^99m TC- SESTAMIBI SPECT/CT FOR THE CHARACTERIZATION OF SMALL RENAL MASSES: INITIAL EXPERIENCE FROM a TERTIARY REFERRAL CENTER

A Review on the Usage of Bone Single-Photon Emission Computed Tomography/Computed Tomography in Detecting Skeletal Metastases in the Post-COVID-19 Era: Is it Time to Ditch Planar and Single-Photon Emission Computed Tomography only Gamma Camera Systems?

Planar whole-body bone scanning (WBS) is widely used to evaluate skeletal lesions seen in cancer and noncancer cases. Frequently, degenerative, or other benign bony changes may give rise to indeterminate lesions that mimic bone metastases. In the post-COVID-19 era, there is an evolutionary phase that puts importance on global development and adaptability, which encompasses to include nuclear medicine practices worldwide. Single-photon emission computed tomography/computed tomography (SPECT/CT) can be used to improve the characterization of these lesions and help to resolve the diagnostic conundrum while reducing the need for patients to undergo multiple different examinations at various imaging departments. The fusion of SPECT and CT allows morphological characterization of functional abnormality detected by focal tracer uptake on planar scintigraphy, which provides a one-stop center imaging in nuclear medicine departments. The objective of this study was to review the diagnostic accuracy of SPECT/CT in diagnosing bone metastases in a variety of oncology and nononcology cases and to determine the feasibility of performing bone SPECT/CT in all suspected cancer cases, including cases of bone infection instead of planar imaging alone. The utilization of hybrid SPECT/CT in indeterminate bone lesions detected on planar WBS can significantly increase the diagnostic confidence and accuracy of image interpretation. Recognition of patterns of disease identified using hybrid imaging can improve the management of patients with potentially lower costs in the long term. Currently, hybrid SPECT/CT machines are becoming a norm in nuclear medicine departments, thus potentially making single planar application machines obsolete in the near future. We hypothesize that in the interest of providing a meaningful interpretation of isotope bone scans, the default protocol should involve the option of acquiring SPECT/CT images rather than relying on whole-body scans only. Departments choosing to upgrade existing equipment or those choosing to invest in only one gamma camera should proactively opt for hybrid SPECT/CT systems.

The Utility of Tc-99m Hydroxydiphosphonate Single-Photon Emission Computed Tomography/Computed Tomography in Symptomatic Kohler's Disease.

Kohler's disease (KD) is a rare disorder of the foot in children where there is avascular necrosis of the navicular bone (NB). It presents with pain and limping and is often misdiagnosed as an infection. However, by adding single-photon emission computed tomography-computed tomography (SPECT-CT) of the foot, the lesion is localized to the NB, leading to the diagnosis of KD. We report the case of a 6-year-old boy with limping and foot pain, who underwent a bone scan using Tc-99m hydroxydiphosphonate and SPECT-CT of the feet. SPECT-CT was necessary not only to localize the exact site of the pathology in an area with small bones but also to confidently reach the diagnosis of KD and proceed with the correct management plan.

CT-free quantitative SPECT for automatic evaluation of %thyroid uptake based on deep-learning

PurposeQuantitative thyroid single-photon emission computed tomography/computed tomography (SPECT/CT) requires computed tomography (CT)-based attenuation correction and manual thyroid segmentation on CT for %thyroid uptake measurements. Here, we aimed to develop a deep-learning-based CT-free quantitative thyroid SPECT that can generate an attenuation map (μ-map) and automatically segment the thyroid.MethodsQuantitative thyroid SPECT/CT data (n = 650) were retrospectively analyzed. Typical 3D U-Nets were used for the μ-map generation and automatic thyroid segmentation. Primary emission and scattering SPECTs were inputted to generate a μ-map, and the original μ-map from CT was labeled (268 and 30 for training and validation, respectively). The generated μ-map and primary emission SPECT were inputted for the automatic thyroid segmentation, and the manual thyroid segmentation was labeled (280 and 36 for training and validation, respectively). Other thyroid SPECT/CT (n = 36) and salivary SPECT/CT (n = 29) were employed for verification.ResultsThe synthetic μ-map demonstrated a strong correlation (R2 = 0.972) and minimum error (mean square error = 0.936 × 10−4, %normalized mean absolute error = 0.999%) of attenuation coefficients when compared to the ground truth (n = 30). Compared to manual segmentation, the automatic thyroid segmentation was excellent with a Dice similarity coefficient of 0.767, minimal thyroid volume difference of − 0.72 mL, and a short 95% Hausdorff distance of 9.416 mm (n = 36). Additionally, %thyroid uptake by synthetic μ-map and automatic thyroid segmentation (CT-free SPECT) was similar to that by the original μ-map and manual thyroid segmentation (SPECT/CT) (3.772 ± 5.735% vs. 3.682 ± 5.516%, p = 0.1090) (n = 36). Furthermore, the synthetic μ-map generation and automatic thyroid segmentation were successfully performed in the salivary SPECT/CT using the deep-learning algorithms trained by thyroid SPECT/CT (n = 29).ConclusionCT-free quantitative SPECT for automatic evaluation of %thyroid uptake can be realized by deep-learning.

Follow-up Tc-99m pyrophosphate cardiac scan for patients with transthyretin cardiac amyloidosis treated with tafamidis.

Tafamidis has been used for treatment of transthyretin cardiac amyloidosis (ATTR-CA). However, Tc-99m pyrophosphate (PYP) cardiac scan for follow-up after tafamidis therapy has not been reported. From May 2017 to March 2022, five patients with or without tafamidis therapy had received two Tc-99m PYP cardiac scans. Tc-99m PYP cardiac scan was performed with planar image and single photon emission computed tomography/computed tomography (SPECT/CT) 3h after administration of Tc-99m PYP. Perugini grading system was applied to determine positive or negative result of the scan. Heart to contralateral lung (H/CL) ratio as well as the difference of H/CL ratio between first and second Tc-99m PYP cardiac scans (ΔH/CL ratio) was calculated. In the five patients participated in this study, three received tafamidis therapy and H/CL ratio was significantly decreased (p = 0.02) after tafamidis therapy. Besides, the ΔH/CL ratio was larger in patients with tafamidis therapy than that in those without tafamidis therapy, albeit not reaching statistical significance (p = 0.2). A decrease in H/CL ratio was found after tafamidis therapy in patients with ATTR-CA, albeit the magnitude of changes in the H/CL ratio (ΔH/CL ratio) was not significantly different from that of patients without tafamidis therapy. Future study with larger population might be required to further clarify the effect of tafamidis therapy on myocardial uptake of Tc-99m PYP. No clinical trial was conducted in our retrospective study.

SPECT/CT, PET/CT and PET/MRI: oncologic and infectious applications and protocol considerations.

Functional imaging is playing an increasingly important role in pediatric radiology. Hybrid imaging techniques utilizing PET/CT (positron emission tomography/computed tomography), PET/MRI (positron emission tomography/magnetic resonance imaging), or SPECT/CT (single photon emission computed tomography/computed tomography) are now available in nearly every clinical practice. There are an increasing number of indications for the use of functional imaging, including oncologic and infectious indications, and it is essential to select and design the hybrid imaging protocol in order to optimize both the functional and anatomic components of the examination. Optimizing the protocol includes strategies for dose reduction, judicious use of contrast media and diagnostic quality imaging as appropriate, and for the greatest reduction in exposure to ionizing radiation, utilizing PET/MRI, whenever available. This review will provide an overview of hybrid imaging protocol considerations with a focus on oncologic and infectious indications.

177Lu]Lu-PSMA-617 theranostic probe for hepatocellular carcinoma imaging and therapy.

This study aimed to explore the feasibility of using [177Lu]Lu-prostate-specific membrane antigen (PSMA)-617 and [177Lu]Lu-Evans blue (EB)-PSMA-617 for in vivo radioligand therapy by single-dose administration in a PSMA-positive hepatocellular carcinoma (HCC) xenograft mouse model. [177Lu]Lu-PSMA-617 and [177Lu]Lu-EB-PSMA-617 were prepared, and labelling efficiency and radiochemical purity were determined. A HepG2 human HCC subcutaneous xenograft mouse model was established. After intravenous injection of [177Lu]Lu-PSMA-617 or [177Lu]Lu-EB-PSMA-617 (37MBq) into the mouse model, single-photon emission computed tomography/computed tomography (SPECT/CT) was performed. Biodistribution studies were conducted to verify targeting specificity and pharmacokinetics. In the radioligand therapy study, mice were randomized into 4 groups: 37MBq [177Lu]Lu-PSMA-617, 18.5MBq [177Lu]Lu-PSMA-617, 7.4MBq [177Lu]Lu-EB-PSMA-617, and saline (control). A single-dose administration was applied at the beginning of therapy studies. Tumor volume, body weight, and survival were monitored every 2days. After the end of therapy, mice were euthanized. Tumors were then weighed, and systemic toxicity was evaluated via blood testing and histological examination of healthy organs. [177Lu]Lu-PSMA-617 and [177Lu]Lu-EB-PSMA-617 were successfully prepared with high purity and stability. SPECT/CT and biodistribution showed that tumor uptake was higher and persisted longer for [177Lu]Lu-EB-PSMA-617 compared with [177Lu]Lu-PSMA-617. [177Lu]Lu-PSMA-617 was rapidly cleared from the blood, while [177Lu]Lu-EB-PSMA-617 persisted for significantly longer. In radioligand therapy studies, tumor growth was significantly suppressed in the 37MBq [177Lu]Lu-PSMA-617, 18.5MBq [177Lu]Lu-PSMA-617, and 7.4MBq [177Lu]Lu-EB-PSMA-617 groups compared to the saline group. Median survival was 40, 44, 43, and 30days, respectively. No healthy organ toxicity was observed in safety and tolerability evaluation. Radioligand therapy using [177Lu]Lu-PSMA-617 and [177Lu]Lu-EB-PSMA-617 significantly suppressed tumor growth and prolonged survival time in PSMA-positive HCC xenograft mice without obvious toxicity. These radioligands appear promising for clinical use in humans, and future studies are warranted.

Sub 4 minute superfast single-photon emission computed tomography/computed tomography as an add-on for problem-solving in planar bone scintigraphy: a time-saving solution for departments without whole-body single-photon emission computed tomography/computed tomography.

Whole-body bone scintigraphy remains widely used in nuclear medicine as it is a relatively inexpensive and quick test in which the whole body can be imaged with good sensitivity. However, one downside of the technique is its lack of specificity. The difficulty comes when there is a single 'hot spot' which usually requires further anatomical imaging to identify the cause and differentiate malignant from benign lesions. In this situation, hybrid imaging with single-photon emission computed tomography/computed tomography (SPECT/CT) can be a useful problem solver. The addition of SPECT/CT can however, be time-consuming, adding up to 15-20 min for every bed position required, a process that can tax the compliance of the patient and reduce the scanning capacity of the department. We report the successful implementation of a new superfast SPECT/CT protocol comprising a 1 s per view over 24 views point and shoot approach, reducing the SPECT scan time to less than 2 min and the whole SPECT/CT to under 4 min while still producing images that allow diagnostic certainty in previously equivocal lesions. This is faster than previously reported ultrafast SPECT/CT protocols. The utility of the technique is demonstrated in a pictorial review of four disparate causes of solitary bone lesions: fracture, metastasis, degenerative arthropathy and Paget's disease. This technique may prove a cost-effective problem-solving adjunct in nuclear medicine departments unable to yet offer whole-body SPECT/CT to every patient, without adding much burden to the department's gamma camera usage and patient throughput.

Multimodal Fusion Network for Detecting Hyperplastic Parathyroid Glands in SPECT/CT Images.

In secondary hyperparathyroidism (SHPT) disease, preoperatively localizing hyperplastic parathyroid glands is crucial in the surgical procedure. These glands can be detected via the dual-modality imaging technique single-photon emission computed tomography/computed tomography (SPECT/CT) since it has high sensitivity and provides an accurate location. However, due to possible low-uptake glands in SPECT images, manually labeling glands is challenging, not to mention automatic label methods. In this work, we present a deep learning method with a novel fusion network to detect hyperplastic parathyroid glands in SPECT/CT images. Our proposed fusion network follows the convolutional neural network (CNN) with a three-pathway architecture that extracts modality-specific feature maps. The fusion network, composed of the channel attention module, the feature selection module, and the modality-specific spatial attention module, is designed to integrate complementary anatomical and functional information, especially for low-uptake glands. Experiments with patient data show that our fusion method improves performance in discerning low-uptake glands compared with current fusion strategies, achieving an average sensitivity of 0.822. Our results prove the effectiveness of the three-pathway architecture with our proposed fusion network for solving the glands detection task. To our knowledge, this is the first study to detect abnormal parathyroid glands in SHPT disease using SPECT/CT images, which promotes the application of preoperative glands localization.

Localization Strategy Prior to Radiofrequency Ablation for Primary and Secondary Hyperparathyroidism

Preoperative localization in patients with primary or secondary hyperparathyroidism before radiofrequency ablation (RFA) is crucial. There is currently a lack of consensus regarding imaging protocol. Evaluating the diagnostic performance of ultrasound, four-dimensional computed tomography (4D-CT), and technetium 99m-sestamibi single-photon-emission-computed tomography/computed tomography (SPECT/CT) is necessary for RFA of hyperparathyroidism. This retrospective study recruited patients with primary or secondary hyperparathyroidism who underwent ultrasound, 4D-CT, and SPECT/CT before RFA at a single institution. The sensitivity, accuracy, and receiver operating characteristic curve analysis were used to evaluate the diagnostic performance of the imaging modalities. A total of 33 patients underwent RFA for hyperparathyroidism (8 patients with primary hyperparathyroidism, 25 patients with secondary hyperparathyroidism). Ultrasound had the highest sensitivity (0.953) and accuracy (0.943), while 4D-CT had higher sensitivity and accuracy than SPECT/CT (sensitivity/accuracy, 4D-CT vs. SPECT/CT: 0.929/0.920 vs. 0.741/0.716). Combined ultrasound with 4D-CT and the three combined modalities achieved equivalent, and the highest, diagnostic performance (sensitivity 1.000, accuracy 0.989). The lesion length and volume were important predictors of the diagnostic performance of 4D-CT and SPECT/CT (area under curve of length in 4D-CT/volume in 4D-CT/length in SPECT/volume in SPECT: 0.895/0.834/0.767/0.761). Combined ultrasound with 4D-CT provides optimal preoperative localization prior to RFA in patients with primary or secondary hyperparathyroidism. The length and volume of parathyroid lesions are determinative of the diagnostic performance of 4D-CT and SPECT/CT.

Evaluation of Therapeutic Efficacy and Imaging Capabilities of 153Sm2O3-Loaded Polystyrene Microspheres for Intra-Tumoural Radionuclide Therapy of Liver Cancer Using Sprague-Dawley Rat Model

Introduction: Neutron-activated samarium-153-oxide-loaded polystyrene ([153Sm]Sm2O3-PS) microspheres has been developed in previous study as a potential theranostic agent for hepatic radioembolization. In this study, the therapeutic efficacy and diagnostic imaging capabilities of the formulation was assessed using liver cancer Sprague-Dawley (SD) rat model. Methods: Twelve male SD rats (150-200 g) that implanted with N1-S1 hepatoma cell line orthotopically were divided into two groups (study versus control) to monitor the tumour growth along 60 days of treatment. The study group received an intra-tumoural injection of approximately 37 MBq of [153Sm]Sm2O3-PS microspheres, while control group received an intra-tumoural injection of 0.1 mL of saline solution. A clinical single photon emission computed tomography/computed tomography (SPECT/CT) system was used to scan the rats at Day 5 post-injection to investigate the diagnostic imaging capabilities of the microspheres. All rats were monitored for change in tumour volume using a portable ultrasound system throughout the study period. Histopathological examination (HPE) was performed after the rats were euthanized at Day 60. Results: At Day 60, no tumour was observed on the ultrasound images of all rats in the study group. In contrast, the tumour volumes in the control group were 24-fold larger compared to baseline. Statistically significant difference was observed in tumour volumes between the study and control groups (p < 0.05). The SPECT/CT images clearly displayed the location of [153Sm]Sm2O3-PS in the liver tumour of all rats at Day 5 post-injection. Additionally, the [153Sm]Sm2O3-PS microspheres was visible on the CT images and this has added to the benefits of 153Sm as a CT contrast agent. The HPE results showed that the [153Sm]Sm2O3-PS microspheres remained concentrated at the injection site with no tumour cells observed in the study group. Conclusions: Neutron-activated [153Sm]Sm2O3-PS microspheres demonstrated excellent therapeutic and diagnostic imaging capabilities for theranostic treatment of liver cancer in a SD rat model. Further studies with different animal and tumour models are planned to validate this finding.

Molecular Imaging Diagnosis of Renal Cancer Using 99mTc-Sestamibi SPECT/CT and Girentuximab PET-CT-Current Evidence and Future Development of Novel Techniques.

Novel molecular imaging opportunities to preoperatively diagnose renal cell carcinoma is under development and will add more value in limiting the postoperative renal function loss and morbidity. We aimed to comprehensively review the research on single photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography computed tomography (PET-CT) molecular imaging and to enhance the urologists' and radiologists' knowledge of the current research pattern. We identified an increase in prospective and also retrospective studies that researched to distinguish between benign and malignant lesions and between different clear cell renal cell carcinoma subtypes, with small numbers of patients studied, nonetheless with excellent results on specificity, sensitivity and accuracy, especially for 99mTc-sestamibi SPECT/CT that delivers quick results compared to a long acquisition time for girentuximab PET-CT, which instead gives better image quality. Nuclear medicine has helped clinicians in evaluating primary and secondary lesions, and has lately returned with new and exciting insights with novel radiotracers to reinforce its diagnostic potential in renal carcinoma. To further limit the renal function loss and post-surgery morbidity, future research is mandatory to validate the results and to clinically implement the diagnostic techniques in the context of precision medicine.

Skeletal standardized uptake values obtained using quantitative SPECT/CT for the detection of bone metastases in patients with lung adenocarcinoma.

To assess the utility of skeletal standardized uptake values (SUVs) obtained using quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) in differentiating bone metastases from benign lesions, particularly in patients with lung adenocarcinoma. Patients with lung adenocarcinoma who had undergone whole-body Tc-99m methyl-diphosphonate (99mTc-MDP) bone scans and received late phase SPECT/CT were retrospectively analyzed in this study. The maximum SUV (SUVmax); Hounsfield units (HUs); and volumes of osteoblastic, osteolytic, mixed, CT-negative metastatic and benign bone lesions, and normal vertebrae were compared. Receiver operating characteristic curves were used to determine the optimal cutoff SUVmax between metastatic and benign lesions as well as the cutoff SUVmax between CT-negative metastatic lesions and normal vertebrae. The linear correlation between SUVmax and HUs of metastatic lesions as well as that between SUVmax and the volume of all bone lesions were investigated. A total of 252 bone metastatic lesions, 140 benign bone lesions, and 199 normal vertebrae from 115 patients with lung adenocarcinoma were studied (48 males, 67 females, median age: 59 years). Metastatic lesions had a significantly higher SUVmax (23.85 ± 14.34) than benign lesions (9.67 ± 7.47) and normal vertebrae (6.19 ± 1.46; P < 0.0001). The SPECT/CT hotspot of patients with bone metastases could be distinguished from benign lesions using a cutoff SUVmax of 11.10, with a sensitivity of 87.70% and a specificity of 80.71%. The SUVmax of osteoblastic (29.16 ± 16.63) and mixed (26.62 ± 14.97) lesions was significantly greater than that of osteolytic (15.79 ± 5.57) and CT-negative (16.51 ± 6.93) lesions (P < 0.0001, P = 0.0003, and 0.002). SUVmax at the cutoff value of 8.135 could distinguish CT-negative bone metastases from normal vertebrae, with a sensitivity of 100.00% and a specificity of 91.96%. SUVmax showed a weak positive linear correlation with HUs in all bone metastases and the volume of all bone lesions. SUVmax of quantitative SPECT/CT is a useful index for distinguishing benign bone lesions from bone metastases in patients with lung adenocarcinoma, particularly in the diagnosis of CT-negative bone metastases, but other factors that may affect SUVmax should be considered.

SPECT/CT SUV-based metrics: A promising diagnostic tool in classifying patients with suspected transthyretin cardiac amyloidosis among the different Perugini grades?

The purpose of this study was to evaluate the contribution of single photon emission computed tomography/computed tomography (SPECT/CT) standardized uptake value (SUV) metrics in classifying patients with suspected transthyretin cardiac amyloidosis (ATTR-CA) among the different Perugini grades. One hundred four patients suspected of ATTR-CA underwent planar scintigraphy with bone seeking tracer (99mTc pyrophosphate-PYP). Patients were classified according to the Perugini scale, the H/CL, H/Bone and H/Bkg ratios. A subset of 48 patients received additional SPECT/CT. Single photon emission computed tomography/CT SUV quantitative parameters, of the heart, myocardium, lungs, liver, soft tissues, bone, and SUV ratios (SUVmaxmyo, SUVmaxlungs, SUVmaxliver, SUVmaxbone and SUVmaxsoft tissue ratios), were evaluated in order to investigate potential metrics that could more clearly differentiate Perugini grades. A total of 33.7% of patients were considered grade 0, 34.6% grade 1 and 31.7% grade 2/3. A combination of H/CL >1.33 and H/Bone >0.85 showed the highest sensitivity 100%. Standardized uptake value-based metrics clearly differentiated grade 0 or 1 vs grades 2 or 3, whereas no significant difference was found between grades 0 and 1, or between grades 1 and 2. The combined cut-off values H/CL 1.33 and SUVmaxmyo 2.88 yielded 100% sensitivity and 84.6% specificity in differentiating ATTR-CA positives vs negatives. The metric SUVmaxmyo/SUVmaxliver was the best metric to classify patients with grade 1 as negative (grade 0) or positive (grade 2 or 3). Single photon emission computed tomography/CT SUV metrics could be complementary to planar scintigraphy in classifying patients among the different Perugini grades. The ratio SUVmaxmyo/SUVmaxliver was the only parameter with high affinity to differentiate patients with grade 1, as grade 0 or grade 2/3 for ATTR-CA.