Single-photon Emission Computed Tomography/computed Tomography Research Articles

Diagnostic value of 99mTc-MDP single-photon emission computed tomography/computed tomography in medication-related osteonecrosis of the jaw: A single-center retrospective study of 39 patients.

The focus of this study was to assess the diagnostic effectiveness of 99mTc-MDP single-photon emission computed tomography/computed tomography (SPECT/CT) in pinpointing medication-related osteonecrosis of the jaw (MRONJ). We gathered a total of 39 patients who were suspected of having MRONJ and displayed radionuclide concentration in the jaws on whole-body bone scans. These patients were subjected to simultaneous SPECT/CT fusion imaging of the jaws during delayed imaging. A consistent team of nuclear medicine physicians and oral and maxillofacial surgeons carried out diagnostic evaluations using SPECT/CT image analysis and dental specialist examinations, and the diagnoses were documented. Based on the SPECT/CT image analysis and dental specialist examination outcomes, we calculated the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 99mTc-MDP SPECT/CT in diagnosing suspected MRONJ. Further, we enumerated the number and proportion of patients at each stage. Our findings suggest that 99mTc-MDP SPECT/CT demonstrates high diagnostic precision in patients suspected of MRONJ who display radionuclide concentration in the jaw on whole-body bone scans. Moreover, it proves beneficial in identifying the early stages of MRONJ.

Development of 99mTc-Labeled Complexes with a Niraparib HYNIC Derivative for PARP-Positive Tumor Imaging.

As an enzyme that plays an important role in DNA repair, poly(ADP-ribose) polymerase-1 (PARP-1) has become a popular target for cancer therapy. Nuclear medicine molecular imaging technology, supplemented by radiolabeled PARP-1 inhibitors, can accurately determine the expression level of PARP-1 at lesion sites to help patients choose an appropriate treatment plan. In this work, niraparib was modified with a hydrazinonicotinamide (HYNIC) group to generate the ligand NPBHYNIC, which has an in vitro affinity (IC50) of 450.90 nM for PARP-1. The ligand NPBHYNIC was labeled with technetium-99m and six different coligands to yield [99mTc]Tc-(X/tricine)-NPBHYNIC (X = TPPTS, TPPMS, PSA, PDA, NIC and ISONIC). These complexes were hydrophilic and exhibited good stability in vitro, and low levels of these complexes were taken up by nontarget organs and tissues in Kunming mice. Among these complexes, [99mTc]Tc-(TPPTS/tricine)-NPBHYNIC and [99mTc]Tc-(NIC/tricine)-NPBHYNIC were selected for biodistribution in HeLa tumor-bearing BALB/c nude mice at 2 h post injection. The results revealed that the tumor uptake of [99mTc]Tc-(TPPTS/tricine)-NPBHYNIC (1.02 ± 0.07% ID/g) was greater than that of [99mTc]Tc-(NIC/tricine)-NPBHYNIC (0.36 ± 0.05% ID/g). Additionally, in biodistribution, single-photon emission computed tomography/computed tomography (SPECT/CT) and radioautography experiments, the tumor uptake of [99mTc]Tc-(TPPTS/tricine)-NPBHYNIC was significantly reduced in the blocked group, indicating PARP-1 specificity. Therefore, it has potential for use as a niraparib-based tumor imaging agent that targets PARP-1.

2025 Update Consensus of 99mTc-Pyrophosphate Scintigraphy in the Transthyretin Cardiac Amyloidosis from the Taiwan Society of Cardiology and the Society of Nuclear Medicine of the Republic of China.

This 2025 updated consensus outlines the diagnostic strategy for transthyretin amyloid cardiomyopathy (ATTR-CM). Given that ATTR-CM is a significant contributor to heart failure, this article emphasizes the importance of making an early and precise diagnosis, particularly as new therapeutic options become available. Highlighting the critical importance of an early and accurate diagnosis, particularly in light of emerging therapeutic modalities, this consensus underscores the central role of 99mTc-pyrophosphate (PYP) scintigraphy as a non-invasive diagnostic tool. The consensus calls for the adoption of standardized imaging protocols and interpretation criteria to ensure consistency and reliability across diverse clinical settings. The integration of qualitative and quantitative imaging techniques within a structured diagnostic framework places particular focus on the use of single-photon emission computed tomography/computed tomography (SPECT/CT) imaging to enhance diagnostic precision by minimizing blood pool activity and eliminating overlapping interference. Three-hour imaging is considered to be critical for accurate evaluations and to reduce false-positive findings, and it is recommended for its superior diagnostic accuracy. Moreover, quantitative assessments are also considered to be essential for evaluating myocardial amyloid deposition. This updated consensus provides comprehensive guidelines for clinicians, with the aim of optimizing patient outcomes through precise diagnosis and effective management of ATTR-CM. The consensus concludes by advocating for continued research and refinement of imaging methodologies, particularly to enhance the clinical applicability of 99mTc-PYP scintigraphy and other future developments in nuclear molecular imaging.

Evaluation of long axial field-of-view (LAFOV) PET/CT for post-treatment dosimetry in Yttrium-90 radioembolization of liver tumors: a comparative study with conventional SPECT imaging.

Long axial field-of-view (LAFOV) positron emission tomography/computed tomography (PET/CT) scanners enable high sensitivity and wide anatomical coverage. Therefore, they seem ideal to perform post-selective internal radiation therapy (SIRT) 90Y scans, which are needed, to confirm that the dose is delivered to the tumors and that healthy organs are spared. However, it is unclear to what extent the use of LAFOV PET is feasible and which dosimetry approaches results in accurate measurements. In this retrospective analysis, a total number of 32 patients was included (median age 71, IQR 14), which had hepatocellular carcinoma, cholangiocarcinoma, or liver metastases. All patients underwent SIRT, and the post-therapy scan was acquired on a single photon emission computed tomography/computed tomography (SPECT/CT) and a LAFOV Biograph Quadra PET/CT with a 20-minute acquisition time. Post-treatment dosimetry, regarding the tumor, whole-liver and lung (LMD) absorbed dose was done using an organ-wise (Simplicit90Y) and a voxel-wise approach (HERMIA Dosimetry) which used a semi-Monte Carlo algorithm. The lung shunt fraction (LSF) was also measured using the voxel-wise approach and compared to the planned. The planning, post-treatment SPECT and PET (SPECTpre, SPECTpost, PETpost) median tumor doses based on the organ-wise dosimetry were 276.0Gy (200.0-330.0Gy), 232.0Gy (158.5-303.5Gy) and 267.5Gy (182.5-370.8Gy). In contrast, the median voxel-wise PETpost dose was significantly smaller than the planned SPECTpre (152.5Gy (94.8-223.8Gy); p < 0.00001). Moreover, the median tumor absorbed dose at 90% (D90) of the tumor volume was significantly higher in SPECTpost compared with PETpost (123.5Gy; 81.5-180.0 vs. 30.5Gy; 11.3-106.3; p < 0.00001). The PETpost measured LSF was significantly lower compared to the planned SPECTpre (0.89%; 0.4-1.3% vs. 2.3%; 1.5-3.6%; p < 0.0001). Similarly, the measured PETpost median LMD was considerably lower to the planned SPECTpre (1.2Gy; 0.6-2.3 vs. 2.5Gy; 1.4-4.7; p < 0.0001). LAFOV PET enabled the direct measurement of post therapy lung dose and tumor doses that correlated well with the planned treatment doses. However, current voxel-wise-based tumor dosimetry seems to be inaccurate for LAFOV PET. In addition, dose volume histogram-based metrics also significantly underestimate the delivered dose. Therefore, improved dosimetry tools are needed for reliable voxel-wise 90Y dosimetry to leverage the sensitivity and spatial resolution of LAFOV PET scanners.

The value of semiquantitative analysis of [99mTc]MDP SPECT/CT in localizing responsible lesions for suspected fresh osteoporotic vertebral compression fractures in patients with contraindications to MRI.

The aim of this study was to evaluate the effectiveness of single-photon emission computed tomography/computed tomography (SPECT/CT) in detecting and localizing the causative vertebra in cases of suspected fresh osteoporotic vertebral compression fractures (OVCFs) in patients with contraindications to MRI. A total of 21 patients with severe back pain with 31 suspected OVCF segments and contraindications to MRI were initially identified through radiographs and the back pain-inducing test (BPIT). The responsible vertebral bodies were determined using [99mTc]MDP SPECT/CT before percutaneous vertebroplasty (PVP). Clinical outcomes and radiographic parameters, including basic demographics, injury duration, focal kyphosis (FK), loss of vertebral height (LVH), and relative intensity values (RIVs) for target and nontarget segments in the SPECT/CT were measured. SPECT/CT identified 14 old and 26 fresh OVCFs. Of these, 18 patients with 26 fresh OVCF segments underwent PVP, and achieved satisfactory outcomes. Significant differences were observed in the RIV, FK, and LVH values between the fresh and old OCVF groups (all p < 0.05). RIVs showed a significant negative correlation with injury duration (r = -0.57, p < 0.05), and a positive correlation with LVH (r = 0.43, p < 0.05). Multiple linear regression analysis confirmed that injury duration was an independent predictor of RIVs (p < 0.05). SPECT/CT is useful for detecting and differentiating fresh fractures from old fractures in patients having OVCF who cannot undergo MRI after BPIT validation, allowing these patients to achieve excellent clinical outcomes following PVP. The RIV serves as a valuable parameter for assessing the duration of fresh versus old OVCFs. ChiCTR, ChiCTR 2300077570. Retrospectively registered, http://www.chictr.org.cn/showproj.html?proj=206192.

Application of modified Curie and SIOPEN skeleton scoring systems in 18F-AlF-NOTA-octreotide PET/CT for neuroblastoma.

The study aimed to explore the role of fluorine-18-aluminum fluoride-1,4,7-triazacyclononane-1,4,7-triacetic acid-octreotide (18F-OC) positron emission tomography/computed tomography (PET/CT) in neuroblastoma (NB) and compared it with Iodine-123 labeled metaiodobenzylguanidine (123I-MIBG) scintigraphy with single photon emission computed tomography/computed tomography (SPECT/CT), as well as to investigate the feasibility of the modified Curie scoring system and International Society of Pediatric Oncology Europe Neuroblastoma (SIOPEN) skeleton scoring system applied in 18F-OC PET/CT. Patients with pathologically confirmed NB underwent 123I-MIBG scintigraphy with SPECT/CT and 18F-OC PET/CT according the standard imaging protocols. The interval between the two imaging techniques ranged from 0 to 22days (median interval: 9days). The number of lesions in modified Curie scoring system and SIOPEN skeleton scoring system applied on 123I-MIBG SPECT/CT and 18F-OC PET/CT was compared. A total of 50 NB patients (male: female = 25:25) with a median age of 62-month-old were enrolled. 123I-MIBG and 18F-OC imaging were positive in 22 patients and negative in 27 patients. 1 patient had positive 18F-OC but negative 123I-MIBG results (p = 1.000). In lesion-based analysis, 18F-OC PET/CT revealed more positive lesions than 123I-MIBG scintigraphy with SPECT/CT (57 vs. 44, p < 0.001), regardless of bone/bone marrow lesions (43 vs. 37, p = 0.031) or soft tissue lesions (14 vs. 7, p = 0.016). The Curie scores of the two imaging techniques showed a significant difference (p = 0.047), whereas no statistic difference for SIOPEN scores (p = 0.688). The Curie and SIOPEN scores were significantly higher in patients with the presence of MYCN amplification or positive bone marrow puncture result (p < 0.05). 18F-OC could be used in the evaluation of NB, and the modified Curie scoring system could be used to semi-quantify the disease extent of NB in 18F-OC PET/CT.

Analysis of the application value of SUV in quantitative SPECT/CT for diagnosing benign and malignant bone lesions.

To analyze the application value of standardized uptake value (SUV) in quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) based on the maximum expectation reconstruction algorithm for diagnosing benign and malignant bone lesions. A retrospective analysis was conducted on the clinical data of 83 patients suspected of bone metastasis who underwent quantitative SPECT/CT bone scans in our hospital from September 2023 to July 2024. A total of 91 high-metabolic bone lesions were outlined for SUV measurement, while the spinal SUV of patients with normal bone metabolism were outlined as the control group (46 vertebral bodies). The maximum SUV (SUVmax), mean SUV (SUVmean), and minimum SUV (SUVmin) of benign lesions (benign group), malignant lesions (malignant group), and the control group were measured and compared. Receiver operating characteristic (ROC) curves were plotted to analyze the diagnostic value of SUV in differentiating benign and malignant bone lesions using quantitative SPECT/CT. Based on the final diagnosis determined by pathology and/or imaging follow-up for 6-12 months or more, 50 malignant bone lesions and 41 benign bone lesions were identified. The levels of SUVmax, SUVmean, and SUVmin in the malignant and benign groups were higher than those in the control group, with the malignant group showing higher levels than the benign group (P<0.05). Receiver operating characteristic curve analysis showed that the areas under the curves for SUVmax, SUVmean, and SUVmin were 0.867, 0.909, and 0.896, respectively. The optimal cut-off value for SUVmax was 26.58g/mL, with a specificity of 100% and a sensitivity of 65.27%; for SUVmean, the optimal cutoff value was 12.75g/mL, with a sensitivity of 78.36% and a specificity of 93.54%; for SUVmin, the optimal cut-off value was 9.13g/mL, with a sensitivity and specificity of 81.42% and 89.87%, respectively. The diagnostic detection rate of quantitative SPECT/CT fusion imaging combined with SUVmean analysis (91.21%) was higher than that of conventional SPECT/CT fusion imaging qualitative analysis (74.73%) (P<0.05). Standardized uptake value in quantitative SPECT/CT to some extent supplements the qualitative analysis of tumor bone metastasis and benign bone lesions, offering a higher accuracy in diagnosing tumor bone metastasis and differentiating between benign and malignant lesions compared to conventional SPECT/CT bone fusion imaging.

Adjacent Segment Disease Occurred in Cervical Spine Due to Trauma Rather Than Degeneration: Observation from Skeletal Scintigraphy in a Case of Tetraplegia

Cervical adjacent segment disease (ASD) is a symptomatic condition that may occurr after cervical spine surgery, accounting for approximately 6% of cases requiring a second surgery. However, some cases may lack abnormal radiographic findings, complicating both the diagnosis and treatment planning. We present the case of a 66-year-old male who developed cervical ASD following anterior cervical discectomy and fusion performed due to a traffic accident. The diagnosis was made using single-photon emission computed tomography/computed tomography (SPECT/CT), which disclosed increased uptake in the C3 to C7 vertebral bodies. We suggest that SPECT/CT should be considered for patients presenting with pain following cervical spine surgery to achieve a more accurate diagnosis of ASD.

Diagnostic Ability of Quantitative Parameters of Whole-Body Bone SPECT/CT Using a Full-Ring 360° Cadmium-Zinc-Telluride Camera for Detecting Bone Metastasis in Patients with Prostate Cancer.

This study aimed to assess the diagnostic capability of quantitative parameters from whole-body bone single-photon emission computed tomography/computed tomography (SPECT/CT) in detecting bone metastases in prostate cancer patients; Methods: We retrospectively analyzed 82 prostate cancer patients who underwent staging bone scintigraphy with a full-ring 360° Cadmium-Zinc-Telluride (CZT) SPECT/CT system. From the SPECT/CT images, we measured the maximum (SUVmax) and mean (SUVmean) standardized uptake values at six normal bone sites (skull, humerus, thoracic spine, lumbar spine, iliac bone, and femur), and the SUVmax for both metastatic and benign bone lesions. Ratios of lesion SUVmax-to-maximum and mean uptake values at the skull, humerus, and femur were computed for each lesion; Results: SUVmax and SUVmean at the skull and femur exhibited significantly lower variance compared to those at the thoracic spine, lumbar spine, and iliac bone, and revealed no significant differences between patients with and without bone metastasis. In receiver operating characteristic curve analysis for detecting bone metastasis among 482 metastatic lesions, 132 benign bone lesions, and 477 normal bone sites, the lesion-to-femur mean uptake ratio demonstrated the highest area under the curve value (0.955) among SPECT/CT parameters. Using a cut-off value of 5.38, the lesion-to-femur mean uptake ratio achieved a sensitivity of 94.8% and a specificity of 86.5%; Conclusions: The bone lesion-to-femur mean uptake ratio was the most effective quantitative bone SPECT/CT parameter for detecting bone metastasis in prostate cancer patients. Quantitative analysis of bone SPECT/CT images could thus play a crucial role in diagnosing bone metastasis.

99mTc-Sestamibi SPECT/CT Evaluation of Renal Oncocytomas

Abstract We present 2 cases of the benign renal neoplasm, oncocytoma, evaluated with 99mTc-sestamibi single-photon emission computed tomography/computed tomography (SPECT/CT) imaging. Oncocytoma is a benign, solid enhancing renal mass that resembles the much more common renal cell carcinoma on standard imaging studies. Differentiation can be difficult due to shared imaging and histological characteristics; therefore, diagnosis historically primarily relied on resection. However, in a subset of patients who are poor candidates for surgical excision or percutaneous biopsy, a possible option for planning follow-up management is 99mTc-sestamibi SPECT/CT imaging. These cases highlight the role of 99mTc-sestamibi SPECT/CT imaging in differentiating benign oncocytomas from malignant renal cell carcinomas.

Evaluation of the SwiftScan mode in bone single-photon emission computed tomography (SPECT) imaging: effect on imaging quality and a semi-quantitative analysis.

99mTc-stannous methylene diphosphonate (99mTc-MDP) bone single-photon emission computed tomography/computed tomography (SPECT/CT) imaging plays a crucial role in various clinical applications. Many strategies have been developed to reduce the injection activity and procedure time, improve the patient experience and reduce their anxiety prior to and during SPECT imaging. This study aimed to evaluate the SwiftScan mode and its effect on image quality, and diagnostic performance of malignant skeletal lesions in bone SPECT image. 99mTc-MDP SPECT/CT scans were acquired from the National Electrical Manufacturers Association (NEMA) phantom with a sphere-to-background ratio of 10:1, and 69 patients were enrolled in this retrospective study. The patients who showed abnormal uptake of focal 99mTc-MDP on whole-body bone planar scans, underwent local SPECT/CT scans. The image comparison and analysis were performed in three acquisition modes: SwiftScan; SwiftScan-50% (the SwiftScan mode with a 50% reduction in acquisition time); and step-and-shoot (SS). The image mean count, coefficient of variation (COV), radioactive concentration, and signal-to-background ratio (SBR) were measured for each phantom image. Visual assessment (using a 5-point Likert scale), semi-quantitative analysis [to determine the COV, mean of the standard uptake value (SUVmean), maximum of the standard uptake value (SUVmax), and SBR], and receiver operating characteristics (ROC) curve analysis were performed for clinical assessment. The SwiftScan mode obtained better quality images than the SwiftScan-50% and SS modes, and it also had better sphere clarity and lower background COVs (P<0.05). The mean counts of the SwiftScan, and the corresponding radioactive concentration and SBR were significantly higher than those of the SwiftScan-50% and SS (P<0.05), except in relation to the 13-10 mm spheres. A total of 101 abnormal 99mTc-MDP uptake skeletal lesions were included in the clinical study. The SwiftScan had significantly higher visual scores than both the SwiftScan-50% and SS (P<0.001). Additionally, there were significantly higher visual scores in the SwiftScan-50% than SS (P<0.05). The SwiftScan also had a lower COV, indicating reduced image noise. The SUVmax, SUVmean, and SBR for the skeletal lesions were significantly higher in the SwiftScan than the other two modes (P<0.05). The optimal diagnostic cut-off values of the SUVmax for identifying malignant skeletal lesions in the SwiftScan, SwiftScan-50%, and SS were 17.95, 14.75, and 9.94, respectively, but there was no significant difference among the three modes in terms of their differential diagnostic performance (all P>0.05). The SwiftScan showed significant improvements in image quality and the semi-quantitative analysis of bone SPECT imaging. It reduced the scanning time by 50% without compromising the image quality or diagnostic performance. These findings provide valuable insights that may inform the clinical application of the SwiftScan, enhancing qualitative and quantitative diagnosis in bone SPECT imaging.

Sentinel Lymph Node Detection in Early-Stage Oral Squamous Cell Carcinoma Using Magnetic Resonance Lymphography: A Pilot Study.

Objectives: To assess the efficacy of magnetic resonance (MR) lymphography with gadobutrol contrast for sentinel lymph node (SLN) mapping in early-stage oral squamous cell carcinoma (OSCC). Methods: This pilot study compared the identification of SLNs by MR lymphography using a gadolinium-based contrast agent (gadobutrol) to conventional [99mTc]Tc-nanocolloid lymphoscintigraphy (including single-photon emission computed tomography/computed tomography (SPECT/CT)) in 10 early-stage OSCC patients undergoing SLN biopsy. The patients initially underwent conventional lymphoscintigraphy following the peritumoral administration of indocyanine green [99mTc]Tc-nanocolloid (120 megabecquerel; ~0.5 mL). Subsequently, 0.5-1.0 mL gadobutrol was peritumorally injected, and MR imaging was acquired for 30 min. The following day, the identified SLNs were harvested and subjected to a histopathological assessment. The MR lymphography and [99mTc]Tc-nanocolloid lymphoscintigraphy results were evaluated and compared with respect to those of the SLN identification. The reference standard consisted of a histopathological evaluation of the harvested SLNs, complementary neck dissection specimens, and follow-up data. Results: The MR lymphography detected 16 out of 27 SLNs identified by [99mTc]Tc-nanocolloid lymphoscintigraphy, revealing an additional SLN that did not harbor metastasis. MR lymphography failed to identify any SLNs in one patient. Of the seven histopathologically positive SLNs detected by [99mTc]Tc-nanocolloid lymphoscintigraphy, three were identified by MR lymphography. All patients remained disease-free after a median follow-up of 16 months. Compared to [99mTc]Tc-nanocolloid lymphoscintigraphy, MR lymphography using gadobutrol achieved an SLN identification rate of 59%, a sensitivity of 75%, and a negative predictive value of 86%. Conclusions: MR lymphography using gadobutrol demonstrates limited reliability for SLN mapping in early-stage OSCC.

The application of extraocular muscle maximum standardized uptake value of 99mTc-diethylenetriamine pentaacetic acid orbital single photon emission computed tomography/computed tomography in the assessment of Graves' orbitopathy.

To study the feasibility and value of assessing patients with Graves' orbitopathy (GO) in 99mTc-diethylenetriamine pentaacetic acid (DTPA) orbital single photon emission computed tomography/computed tomography (SPECT/CT) with extraocular muscle maximum standardized uptake value (SUVmax). A total of 235 patients underwent 99mTc-DTPA orbital SPECT/CT, including 176 patients with GO and 59 patients with Graves' disease (GD) as controls. The SUVmax of extraocular muscles, including right medial rectus muscle (RMR), right lateral rectus muscle (RLR), left medial rectus muscle (LMR), left lateral rectus muscle (LLR), was compared between groups, correlation analyses with clinical activity scores (CAS) and serological indices was performed, and the diagnostic efficacy was evaluated using receiver operating characteristic curves. The consistency of SPECT/CT and MRI in assessing extraocular muscle activity was compared. SUVmax in the extraocular muscles of active GO patients was significantly higher than in inactive GO patients and controls. In GO patients, SUVmax of the medial rectus (LMR most prominent) was higher than that of the lateral rectus. SUVmax correlated with CAS, thyroid-stimulating hormone, total cholesterol, low-density lipoprotein (positively) and free triiodothyronine and free thyroxine (negatively), but not with GO duration. The optimal cutoff values for distinguishing between active and inactive SUVmax were identified. RLR had high sensitivity and RMR had high specificity. SPECT/CT and MRI showed moderate agreement in assessing extraocular muscle activity in 87 GO patients, with high concordance. The extraocular muscle SUVmax of 99mTc-DTPA orbital SPECT/CT may be used as an adjunct method in combination with CAS to more accurately assess GO activity, which can help in clinical diagnosis and individualized treatment.

Pre-symptomatic scintigraphic and genetic cascade screening in cardiac transthyretin amyloidosis.

While early diagnosis is crucial, as new treatments can significantly slow the progression of the disease, there is growing evidence on the application of novel imaging techniques for detecting transthyretin amyloidosis (ATTR) in pre-symptomatic stages. This study aimed to evaluate the utility of pre-symptomatic scintigraphic imaging cascade screening for early detection of ATTR. During the period from 2020 to 2024, we conducted a prospective study that enrolled 100 consecutive adults. The study utilized a multimodal cascade screening approach to assess asymptomatic relatives of individuals with ATTR (ClinicalTrials.gov Identifier: NCT05814380). The analysis incorporated clinical data, genetic testing, echocardiography, scintigraphy and single-photon emission computed tomography/computed tomography (SPECT/CT) with [99mTc]Tc-DPD, regardless of the predicted age of disease onset. Overall, scintigraphy identified cardiac amyloidosis (CA) in 8.2% of relatives, while 20.5% carried a pathogenic transthyretin variant without radiotracer uptake, with Phe53Leu being predominant. Notably, no relatives of wild-type ATTR patients exhibited CA on scintigraphy or carried a transthyretin variant. Additionally, newly-diagnosed relatives with ATTR CA presented elevated high-sensitivity troponin levels and exhibited a higher incidence of pathological electrocardiographic Q waves, greater thickness of the intraventricular septum and left ventricular posterior wall, a notable decline in lateral wall and intraventricular septal E' tissue velocities measured by TDI, and the "5-5-5" sign (p < 0.05). The presented findings demonstrate that implementing a systematic screening protocol, which integrates genetic and scintigraphic testing, facilitates the early detection of ATTR. Crucially, a significant proportion of asymptomatic relatives of patients with hereditary ATTR may suffer from underlying CA. ClinicalTrials.gov Identifier: NCT05814380.

Efficacy of additional lateral pinhole and SPECT/CT imaging in dual-phase Tc-99m MIBI parathyroid scintigraphy for localising parathyroid pathologies in patients with primary hyperparathyroidism: a single-institution experience.

Parathyroid imaging with dual-phase technetium-99m methoxyisobutrylizonitrile (Tc-99m MIBI) scintigraphy serves as an important prerequisite for the identification of hyperfunctioning parathyroid gland(s) in patients with primary hyperparathyroidism (PHPT) for a successful targeted parathyroidectomy. This study aimed to evaluate the clinical value of additional lateral imaging and single-photon emission computed tomography/computed tomography (SPECT/CT) versus conventional planar imaging for locating parathyroid pathologies in patients with PHPT. A retrospective review was performed on 105 patients who underwent dual-phase Tc-99m MIBI scintigraphy and were surgically treated by parathyroidectomy. Dual-phase Tc-99m-MIBI planar scintigraphy with additional lateral pinhole views and SPECT/CT imaging was performed on a routine basis, as per departmental protocol. Comparison study between imaging modalities was done by patient-based analysis and scintigraphy results were compared with the clinical findings, biochemical markers, and histopathological findings. Sensitivity and specificity for anterior planar dual-phase Tc-99m MIBI scintigraphy were 78.8 and 80%, respectively. In comparison, lateral pinhole scan and SPECT/CT alone were found to have sensitivities of 85.9 and 90.9%, respectively, with the same specificity. Sensitivity decreased in patients with normocalcaemia and multiglandular disease. The mean adenoma weight and size for true-positive studies were significantly higher than those for false-negative or false-positive studies. SPECT/CT provided the highest diagnostic accuracy for preoperative identification of parathyroid lesions in PHPT patients. Lateral pinhole imaging offers comparable sensitivity and aids in adenoma localisation when SPECT/CT is unavailable.

Molecular Imaging of Melanoma VEGF-expressing Tumors through [99mTc]Tc-HYNIC-Fab(Bevacizumab).

Angiogenesis is a process that many tumors depend on for growth, development, and metastasis. Vascular endothelial growth factor (VEGF) is one of the major players in tumor angiogenesis in several tumor types, including melanoma. VEGF inhibition is achieved by bevacizumab, a humanized monoclonal antibody that binds with high affinity to VEGF and prevents its function. In order to successfully enable in vivo VEGF expression imaging in a murine melanoma model, we previously labeled bevacizumab with [99mTc]Tc. We observed that this was feasible, but it had prolonged blood circulation and delayed tumor uptake. The aim of this study was to develop a radiolabeled Fab bevacizumab fragment, [99mTc]Tc-HYNICFab( bevacizumab), for non-invasive in vivo VEGF expression molecular imaging. Flow cytometry was used to examine VEGF presence in the murine melanoma cell line (B16-F10). Bevacizumab was digested with papain for six hours at 37°C to produce Fab(bevacizumab), which was then conjugated to NHS-HYNIC-Tfa for radiolabeling with [99mTc]Tc. Stability and binding affinity assays were also evaluated. Biodistribution and single photon emission computed tomography/computed tomography (SPECT/CT) were performed at 1, 3, and 6 h (n = 4) after injection of [99mTc]Tc-HYNIC-Fab(Bevacizumab) in normal and B16-F10 tumor-bearing C57Bl/6J mice. Using flow cytometry, it was shown that the B16-F10 murine melanoma cell line has intracellular VEGF expression. Papain incubation resulted in the complete digestion of bevacizumab with good purity and homogeneity. The radiolabeling yield of [99mTc]Tc-HYNIC-Fab(bevacizumab) was 85.00 ± 6.06%, with a specific activity of 291.87 ± 18.84 MBq/mg (n=3), showing in vitro stability. Binding assays demonstrated significant intracellular in vitro VEGF expression. Fast blood clearance and high kidney and tumor uptake were observed in biodistribution and SPECT/CT studies. We present the development and evaluation of [99mTc]Tc-HYNIC-Fab(bevacizumab), a novel molecular VEGF expression imaging agent that may be used for precision medicine in melanoma and potentially in other VEGF-expressing tumors.

DPD quantification correlates with ECV and disease severity in patients with ATTR-CM

Abstract Background The pathophysiological hallmark of transthyretin amyloid cardiomyopathy (ATTR-CM) is the deposition of amyloid within the myocardium. However, the association between myocardial amyloid load and quantitative cardiac 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) uptake is barely investigated. Purpose We aimed to investigate the relationship between quantitative cardiac 99mTc-DPD uptake and myocardial amyloid load, assessed by extracellular volume (ECV) on cardiac magnetic resonance (CMR) imaging, along with cardiac function in patients with ATTR-CM. Methods Forty ATTR-CM patients underwent 99mTc-DPD single-photon emission computed tomography/computed tomography (SPECT/CT) and CMR imaging. Results We observed significant correlations (r, Spearman's correlation coefficient) between the standardized uptake value (SUV) retention index and myocardial amyloid load (ECV: r=0.677, p&amp;lt;0.001; native T1 time: r=0.430, p=0.006), longitudinal cardiac function [right ventricular longitudinal strain (RV-LS): r=0.472, p=0.002], cardiac biomarkers (NT-proBNP: r=0.543, p&amp;lt;0.001; troponin T: r=0.401, p=0.011), exercise capacity [6-min walking distance (6MWD): r=-0.410, p=0.010] and disease stage [National Amyloidosis Centre (NAC) ATTR stage: r=0.479, p=0.002]. ATTR-CM patients were divided into two cohorts based on the median of the SUV retention index (low cardiac uptake: &amp;lt;5.19 mg/dL, n=20; high cardiac uptake: ≥5.19 mg/dL, n=20). We observed significant between-cohort differences in terms of ECV (p&amp;lt;0.001), native T1 time (p=0.011), RV-LS (p=0.007), NT-proBNP (p&amp;lt;0.001), troponin T (p=0.030), 6MWD (p=0.002) and NAC ATTR stage (I: p&amp;lt;0.001, II: p=0.030, III: p=0.021). Conclusions In ATTR-CM, quantitative cardiac 99mTc-DPD uptake correlates with myocardial amyloid load, longitudinal cardiac function, cardiac biomarkers, exercise capacity, and disease stage. DPD quantification may provide a valuable tool for quantifying and monitoring cardiac disease burden in affected individuals.Table.Baseline Characteristics.Figure.Correlations.

Can bone SPECT/CT determine optimal sites for microbiological identification in post-traumatic or chronic osteomyelitis of extremities?

IntroductionAccurate microbiological identification is crucial when managing chronic osteomyelitis (COM) and post-traumatic osteomyelitis (PTO). Although bone single photon emission computed tomography/computed tomography (SPECT/CT) has helped in localizing osteomyelitis lesions, its effectiveness in guiding microbiological sampling remains unclear. This study aimed to determine whether bone SPECT/CT can improve microbiological identification rates in COM or PTO of the extremities. Patients and methodsFrom February 2020 to August 2024, 53 patients with suspected COM or PTO in the extremities were retrospectively analyzed. All patients underwent bone SPECT/CT, followed by microbiological sampling during surgery. Tissue samples were taken from the areas of high SPECT/CT uptake or based on intraoperative findings where no uptake was observed. Microorganism identification rates were analyzed, including a sub-group analysis based on antibiotic discontinuation. ResultsOf the 53 patients, 42 had positive bone SPECT/CT scan findings, with pathogen identification in 30 patients (71.4 %). In contrast, pathogen identification occurred in one out of twelve patients (9.1 %) with negative findings (odds ratio 25, p< 0.001). Bone SPECT/CT demonstrated a sensitivity of 96.8 % and an overall accuracy of 75.5 %. When antibiotics had been discontinued for ≥2 weeks, the pathogen identification rate increased to 90 %, compared with 50 % for <2 weeks of discontinuation (odds ratio 10.0, p= 0.006). In a sub-group of 30 patients with adequate antibiotic discontinuation duration, a positive bone SPECT/CT scan yielded a pathogen identification rate of 90.1 % (odds ratio 60.0, p= 0.001). ConclusionBone SPECT/CT effectively identifies optimal sites for microbiological sampling in COM and PTO of the extremities, particularly when antibiotics have been discontinued for ≥2 weeks, enhancing pathogen detection rates.

Validation of radiolabelled exendin for beta cell imaging by ex vivo autoradiography and immunohistochemistry of human pancreas

BackgroundEstimation of beta cell mass is currently restricted to evaluating pancreatic tissue samples, which provides limited information. A non-invasive imaging technique that reliably quantifies beta cell mass enables monitoring of changes of beta cell mass during the progression of diabetes mellitus and may contribute to monitoring of therapy effectiveness. We assessed the specificity of radiolabelled exendin for beta cell mass quantification in humans. Fourteen adults with pancreas tumours were injected with 111In-labeled exendin-4 prior to pancreatic resection. In resected pancreas tissue, endocrine-exocrine ratios of tracer uptake were determined by digital autoradiography and accumulation of 111In-labeled exendin-4 was compared to insulin and GLP-1 receptor staining. Of four participants, abdominal single photon emission computed tomography/computed tomography (SPECT/CT) images were acquired to quantify pancreatic uptake in vivoResultsTracer uptake was predominantly present in the endocrine pancreas (endocrine-exocrine ratio: 3.6 [2.8–10.8]. Tracer accumulation showed overlap with insulin-positive regions, which overlapped with GLP-1 receptor positive areas. SPECT imaging showed pancreatic uptake of radiolabelled exendin in three participants.ConclusionRadiolabelled exendin specifically accumulates in the islets of Langerhans in human pancreas tissue. The clear overlap between regions positive for insulin and the GLP-1 receptor substantiate the beta cell specificity of the tracer. Radiolabelled exendin is therefore a valuable imaging agent for human beta cell mass quantification and has the potential to be used for a range of applications, including improvement of diabetes treatment by assessment of the effects of current and novel diabetes therapies on the beta cell mass.Trial registrationClinicalTrials.gov NCT03889496, registered 26,032,019, URL https://clinicaltrials.gov/study/NCT03889496?term=NCT03889496. ClinicalTrials.gov NCT04733508, registered 02022021, URL https://clinicaltrials.gov/study/NCT04733508.

Deep-learning-based attenuation map generation in kidney single photon emission computed tomography

BackgroundAccurate attenuation correction (AC) is vital in nuclear medicine, particularly for quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) imaging. This study aimed to establish a CT-free quantification technology in kidney SPECT imaging using deep learning to generate synthetic attenuation maps (μ-maps) from SPECT data, thereby reducing radiation exposure and eliminating the need for CT scans.ResultsA dataset of 1000 Tc-99m DTPA SPECT/CT scans was analyzed for training (n = 800), validation (n = 100), and testing (n = 100) using a modified 3D U-Net for deep learning. The study investigated the use of primary emission and scattering SPECT data, normalization methods, loss function optimization, and up-sampling techniques for optimal μ-map generation. The problem of checkerboard artifacts, unique to μ-map generation from SPECT signals, and the effects of iodine contrast media were evaluated. The addition of scattering SPECT to primary emission SPECT imaging, logarithmic maximum normalization, the combination of absolute difference loss (L1) and three times the absolute gradient difference loss (3 × LGDL), and the nearest-neighbor interpolation significantly enhanced AI performance in μ-map generation (p < 0.00001). Checkerboard artifacts were effectively eliminated using the nearest-neighbor interpolation technique. The developed AI algorithm produced μ-maps neutral to the presence of iodine contrast and showed negligible contrast effects on quantitative SPECT measurement, such as glomerular filtration rate (GFR). The potential reduction in radiation exposure by transitioning to AI-based CT-free SPECT imaging ranges from 45.3 to 78.8%.ConclusionThe study successfully developed and optimized a deep learning algorithm for generating synthetic μ-maps in kidney SPECT images, demonstrating the potential to transition from conventional SPECT/CT to CT-free SPECT imaging for GFR measurement. This advancement represents a significant step towards enhancing patient safety and efficiency in nuclear medicine.