Single-photon Emission Computed Tomography/computed Tomography Research Articles

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<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<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: <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<0.001), native T1 time (p=0.011), RV-LS (p=0.007), NT-proBNP (p<0.001), troponin T (p=0.030), 6MWD (p=0.002) and NAC ATTR stage (I: p<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.

Use of technetium-99m-pyrophosphate single-photon emission computed tomography/computed tomography in monitoring therapeutic changes of RNA interference therapeutics in patients with hereditary transthyretin amyloid cardiomyopathy

BackgroundRNA interference therapeutics reduce transthyretin production; however, their effect on hereditary transthyretin amyloid cardiomyopathy (ATTR-CA) remains unclear. We aimed to investigate alterations in technetium-99 m (99mTc)-pyrophosphate (PYP) single-photon emission computed tomography/computed tomography (SPECT/CT) outcomes in patients receiving patisiran or vutrisiran. MethodsWe retrospectively identified individuals with hereditary ATTR-CA who received patisiran or vutrisiran. First and second 99mTc-PYP SPECT/CT data, including visual grading, planar heart to contralateral lung (H/CL) ratio, and volumetric heart to lung (H/L) ratio were assessed. ResultsEight patients with hereditary ATTR-CA were enrolled. Cohort A included four patients who underwent their first 99mTc-PYP SPECT/CT imaging at the initiation of small interfering RNA (siRNA) treatment, while cohort B comprised four patients who had been receiving siRNA treatment before their first 99mTc-PYP SPECT/CT imaging (median duration 1281 days). Overall, there were numerical reductions in planar H/CL ratio (1.7 ± 0.2 to 1.6 ± 0.1, p = 0.050) and a significant improvement in volumetric H/L ratio (4.0 ± 0.9 to 3.5 ± 0.4, p = 0.035). Although without significance, subgroup analysis showed more pronounced changes in cohort A for both planar H/CL ratio and volumetric H/L ratio (−20.1 ± 12.6% and −17.1 ± 11.4%) compared to cohort B (−3.3 ± 11.2% and −4.3 ± 12.7%). ConclusionOur results demonstrated a significant decrease in volumetric H/L ratio in hereditary ATTR-CA patients receiving RNA interference therapeutics.

Orthopedic Applications of Single-photon Emission Computed Tomography/Computed Tomography in Identifying Pain Generators in the Pre- and Post-operative Patient

Postoperative and benign bone pathologies can sometimes be difficult to elicit on purely anatomical-based imaging. Single-photon emission computed tomography-computed tomography (SPECT-CT) is an established modality with emerging applications in the musculoskeletal field that combines cross-sectional structural imaging with the metabolic data. It is thought to offer certain clinical advantages to conventional imaging modalities as it can be sensitive to conditions before they appear as a structural abnormality. The aim of this pictorial review is to demonstrate the musculoskeletal applications of SPECT/CT in the pre- and post-operative orthopedic patient. The evidence for the musculoskeletal application of SPECT/CT is reviewed in various pre- and post-operative patients focusing on the advantages and disadvantages of this imaging modality alongside conventional imaging. Alongside this we present a series of musculoskeletal SPECT/CT cases in postoperative spinal and extremity joints identifying such pathologies as loosening, pseudoarthroses and prosthetic joint infection. We also include cases on the nonoperative joint identifying pain generators for targeted therapy. This review has shown that SPECT/CT can be a useful adjunct alongside other conventional imaging modalities in identifying musculoskeletal pain generators in the postoperative patient. It is especially useful in situations where anatomical imaging modalities alone provide insufficient diagnostic information or lack of symptomatic improvement. SPECT/CT is therefore likely to remain an complimentary investigative tool for unidentified musculoskeletal pain or for postoperative patients with metalwork in situ.

Evaluation of jaw pathologies of patients with medication-related osteonecrosis of the jaw using a computer program to assess the bone scan index: comparison of standardized uptake values with bone SPECT/CT.

The aim of this study is to investigate the jaw pathologies of patients with medication-related osteonecrosis of the jaw (MRONJ) using a computer program to assess the bone scan index (BSI), especially comparison of standardized uptake values (SUVs) with bone single-photon emission-computed tomography/computed tomography (SPECT/CT). Sixty-three patients with MRONJ underwent bone SPECT/CT in this prospective study. BSI and high-risk hot spot as bone metastases in the patients with MRONJ were evaluated using a computer program for BSI that scanned SPECT/CT and automatically defined the data. The maximum and mean SUVs with SPECT/CT were obtained using commercially available software. Statistical analyses were performed by Pearson chi-square test, Mann-Whitney U-test, or one-way analysis of variance with Tukey's honestly significant difference test. A P value lower than 0.05 was considered statistically significant. The maximum and mean SUVs for a high-risk hot spot of the jaw with MRONJ [28.2 ± 10.2 and 11.7 ± 3.8; n = 6 (6/63 : 9.5%)] were significantly higher than those for a low-risk hot spot [18.5 ± 6.4 and 6.2 ± 1.9; n = 23 (23/63 : 36.5%)] and no-risk hot spot [14.2 ± 9.4 and 5.3 ± 5.1; n = 34 (34/63 : 54.0%)], respectively. The computer program for BSI indicated that 9.5% of the jaw with MRONJ were false positive of bone metastases. The study suggests that high-risk hot spots of the jaw with MRONJ depend on the SUVs.

Comparison between the use of one and two CT scans for attenuation correction of rest-stress myocardial perfusion SPECT with Tc-99m sestamibi

Background: The standard protocol is to use separate computed tomography (CT) scans acquired during rest and stress for attenuation correction (AC) of myocardial perfusion (MP) single photon emission computed tomography (SPECT) imaging. Recently, there have been attempts to reduce the radiation dose by using one CT instead of two CTs. Objective: To compare between the use of one and two CTs for AC of rest-stress MP SPECT with Tc-99m sestamibi in quantification of MP and left ventricle (LV) function. Materials and Methods: Gated rest-stress MP SPECT images of 107 patients were reprocessed using 3 different AC methods: 1) rest CT for AC of rest SPECT and stress CT for AC of stress SPECT (2CT); 2) rest CT for AC of both rest and stress SPECT (1CT-rest); and 3) stress CT for AC of both rest and stress SPECT (1CT-stress). SPECT images obtained from 2CT and 1CT were used for quantification of MP values and LV function values. The values from 2CT and 1CT were compared. Results: The MP values of 2CT and 1CT showed a strong correlation (r≥0.712) and they did not differ significantly (p=0.106 to 0.931). In contrast, the LV function values of 2CT and 1CT exhibited a very strong correlation (r≥0.960), but they differ significantly (p=&lt;0.001 to 0.004). Conclusions: The use of one and two CTs for AC in rest-stress MP SPECT with Tc-99m sestamibi can be interchanged for the quantification of MP, but not for the quantification of LV function.

Imaging bone turnover assessment through volumetric density-adjusted standardized uptake value using quantitative bone SPECT/CT in osteoporosis

BackgroundSerum bone turnover markers offer limited insight into metabolic activity at the individual vertebra level in osteoporosis. This study introduces a novel image-derived bone turnover marker for individual vertebrae to address this limitation, utilizing volumetric density-adjusted quantitative bone single-photon emission computed tomography/computed tomography (SPECT/CT) with [99mTc]Tc-DPD. This retrospective study included 177 lumbar vertebrae from 55 postmenopausal South Korean women. The mean standardized uptake value (SUVmean, g/cm3) and volumetric bone mineral density (vBMD, mg/cm3) were determined within a 2-cm³ volume of interest in the trabecular portion of each vertebra using quantitative SPECT and CT. The density-adjusted mean standardized uptake value (dSUVmean) was calculated by dividing the SUVmean by the vBMD and multiplying by 1,000.ResultsSUVmean correlated positively with vBMD (r = 0.60, p < 0.001). Conversely, dSUVmean correlated negatively with vBMD (ρ = −0.66, p < 0.001), highlighting the inverse relationship between bone mass and turnover after density adjustment of SUVmean. Patients with major osteoporotic fractures had lower vBMD (62.5 ± 29.4 vs. 92.3 ± 27.4 mg/cm³, p = 0.001) but higher dSUVmean (100.8 ± 60.7 vs. 62.6 ± 17.5, p = 0.001) compared to those without fractures, reinforcing the association between fracture prevalence, low bone mass, and high bone turnover.ConclusionVolumetric density-adjusted quantitative bone SPECT/CT offers a novel image-derived bone turnover marker for assessing bone turnover in osteoporosis. This method provides a precise assessment of fragility at the individual vertebra level, which may enhance personalized osteoporosis management.

Prospective study of dual-phase 99mTc-MIBI SPECT/CT nomogram for differentiating non-small cell lung cancer from benign pulmonary lesions

ObjectivesTo establish and validate a technetium 99m sestamibi (99mTc-MIBI) single-photon emission computed tomography/computed tomography (SPECT/CT) nomogram for predicting non-small cell lung cancer (NSCLC). Comparing the diagnostic performance of early and delayed SPECT/CT nomogram, and compare the diagnostic performance of SPECT/CT radiomics models with single SPECT and CT radiomics models. MethodsThis prospective study included 119 lesions (NSCLC: n = 92, benign pulmonary lesions: n = 27) from 103 patients (mean age: 59.68 ± 8.94 years). Patients underwent dual-phase 99mTc-MIBI SPECT/CT imaging. They were divided into the training (n = 83) and validation (n = 36) cohorts. Logistic regression, support vector machine, random forest, and light-gradient boosting machine were applied to train and determine the optimal machine learning model. Then, combining radiomics score and clinical factors, establish nomograms for diagnosing NSCLC. ResultCYFRA21-1 was selected for constructing the clinical model. In early imaging, the areas under the curve (AUCs) of the clinical model, radiomics model, and nomogram were 0.571, 0.830, and 0.875, respectively. The nomogram performed better than the clinical model and similarly to the radiomics model (P=0.020, P=0.216), and there are no statistically significant differences in the predictive performance between the radiomics model and the clinical model (P=0.103). In delayed imaging, the AUC was 0.643, 0.888, and 0.893, respectively. The predictive performance of the nomogram was superior compared to the clinical model and comparable to the radiomics model (P=0.042, P=0.480), and the radiomics model also demonstrated superior diagnostic performance compared to the clinical model (P=0.049). Compared to early SPECT/CT results, the AUC values of the nomogram and radiomics models in the delayed phase were higher, although no statistical differences were found (P=0.831, P=0.568). In delayed imaging, the AUC of the radiomics models for CT and SPECT was 0.696 and 0.768, respectively, SPECT/CT radiomics exhibited significant differences compared with CT and SPECT alone (P=0.042, P=0.038). ConclusionDual-phase 99mTc-MIBI SPECT/CT nomograms and radiomics models can effectively predict NSCLC, providing an economically and non-invasive imaging method for diagnosing NSCLC, moreover, these findings provide a basis for early diagnosis and treatment strategies in NSCLC patients. Delayed-phase SPECT/CT imaging may offer greater practical value than early-phase imaging for diagnosing NSCLC. However, this novel approach necessitates further validation in larger, multi-center cohorts. Clinical relevanceRadiomics nomogram based on SPECT/CT for discriminating NSCLC from benign lung lesions helps to aid early diagnosis and guide treatment. Key pointsNomograms, based on dual-phase SPECT/CT, was constructed to discriminate between non-small cell lung cancer and benign lesions.SPECT/CT radiomics model has better predictive performance than SPECT and CT radiomics model.

A Rare and Intriguing Case of Papillary Thyroid Carcinoma with Tumor Thrombus Extending into the Right Ventricle: Documentation with 131I-NaI-SPECT/CT, MRI, and 18F-FDG-PET/CT

AbstractA unique case of papillary carcinoma of the thyroid with an extensive tumor thrombus extending into the right ventricle is presented. The patient was a known case of solid variant of papillary carcinoma of thyroid, post three cycles of radioiodine therapy, had reported for a diagnostic 131I-NaI scintigraphy as a part of the workup for planning the next 131I therapy. Clinically, the patient was asymptomatic. 131I-NaI scintigraphy showed an arcuate pattern concentration of tracer in the upper mediastinum, which descended up to the lower mediastinum. A 131I-NaI single photon emission computed tomography/computed tomography (SPECT/CT) showed a tracer avid tumor with an extensive tumor thrombus extending from the left brachiocephalic vein to the right ventricle. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) and magnetic resonance imaging (MRI) demonstrated similar findings. The patient was decided to be managed with tyrosine kinase inhibitors as surgical intervention was not deemed possible due to the involvement of major vessels and the high risk of bleeding.

Evaluation of patients' radiation doses and establishment of institutional diagnostic reference levels in nuclear medicine in Oman.

This study aimed to develop diagnostic reference levels (DRLs) in Single Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) and Positron Emission Tomography/Computed Tomography (PET/CT) imaging for the most frequent SPECT/CT and PET/CT examinations performed at our institution. A total of 1134 adult patients, who have undergone SPECT/CT and PET/CT scanning over a period of 4years (2018-2021), were included. The scans consisted of 401 PET/CT and 733 SPECT/CT scans. The CT dosimetry data [CT-dose-index (CTDIvol), dose-length-product (DLP)] and administered activities were collected. The DRLs were calculated for CTDIvol, DLP and administrated activity. The estimated DRLs are given as [median CTDIvol (mGy):median DLP (mGy.cm):median administrated activity (MBq)]: whole body PET/CT: 1.88:175:259; brain PET/CT: 12.9:300:239; cardiac PET/CT: 1.34:32:368; bone SPECT/CT: 2.68:116:763; MPI SPECT/CT (stress-rest): 1.49:52:751-721; parathyroid SPECT/CT: 3.1:126:779; thyroid uptake SPECT: 3.52:147:195; thyroid post-ablation SPECT/CT: 3.85:160:NA. The derived DRLs have allowed careful monitoring of doses delivered to patients and could act as a trigger to investigate doses that systematically exceeds the derived DRLs.

Imaging of Chromophobe Renal Cell Carcinoma with 99mTc-Sestamibi SPECT/CT: Considerations Regarding Risk Stratification and Histologic Reclassification.

Indeterminate renal masses are increasingly incidentally found on cross-sectional imaging. 99mTc-sestamibi single-photon emission computed tomography/computed tomography (SPECT/CT) scans can be used to identify oncocytomas and oncocytic renal neoplasms, including a subset of chromophobe renal cell carcinomas (chRCCs), which are viewed as false-positive. Patients imaged with renal sestamibi scans between 2014 and 2023 were reviewed. Those patients with solitary tumors that were originally classified as chRCC were included in the analysis. Imaging with SPECT/CT from the liver dome down had been carried out 75min after the administration of 925MBq of 99mTc-sestamibi. All available H&E and immunostained slides were re-reviewed and classified according to WHO 2022 criteria. Confirmatory immunohistochemical stains were performed in tumors considered morphologically suspicious for non-chRCC entities. A total of 18 patients with solitary tumors were included in the final analysis. 13/18 (72.2%) tumors in this cohort remained classified as chRCC, with 4/18 (22.2%) being eosinophilic-variant chRCC. The reclassified tumors (5/18 [27.8%]) included 2/18 (11.1%) low-grade oncocytic tumor (LOT), 1/18 (5.5%) eosinophilic vacuolated tumor (EVT), and 2/18 (11.1%) unclassified low-grade oncocytic neoplasms. As such, only 2/9 (22.2%) qualitatively "hot" tumors were chRCC other than eosinophilic-variant and only 1/9 (11.1%) "cold" tumors was a histology other than chRCC. Based on current histopathologic classification methods, it is likely that the "false-positive" rate of uptake on renal sestamibi scans with chRCC has been over-stated. Further study is warranted to better refine the optimal utility of renal sestamibi scans for non-invasive risk stratification of indeterminate renal masses.

Incidence of exclusive extrapelvic skeletal metastasis in prostate carcinoma on bone scintigraphy.

Bone is one of the common sites of metastasis from prostate carcinoma. Bone scintigraphy (BS) is one of the most sensitive imaging modalities currently used for bone metastatic work-up. Skeletal metastasis in prostate carcinoma commonly involves pelvic bones but rarely involves extrapelvic-extraspinal sites. To retrospectively analyze the BS data to determine the pattern of skeletal metastases in the prostate carcinoma. This retrospective observational study involves patients with biopsy-proven prostate carcinoma referred for BS for staging assessment. Patients with abnormal BS were evaluated for the pattern of skeletal involvement and data were presented in descriptive format in the form of percentages. A total of 150 patients with biopsy-proven prostate cancer who were referred for staging were included in the study. Thirteen of 150 patients (8.67%) had no abnormal uptake on planar images, ruling out metastatic disease. Twenty-four patients (16%) had heterogeneous uptake in the spine with distribution characteristic of degenerative disease and no scan pattern of metastatic disease. Thirty patients (20%) had multifocal uptake involving both pelvic and extra pelvic bones on planar images typical for skeletal metastasis and were considered metastatic. Eighty-three out of 150 patients (55.3%) had increased tracer uptake, which was indeterminate, thus, single photon emission computed tomography-computed tomography (SPECT-CT) was acquired, which showed 51 with metastatic disease, 31 benign lesions, and one indeterminate finding. Seven of 150 patients had exclusive pelvic bone uptake, which was found to be metastatic in 4/7 patients in SPECT-CT. Fifty six out of 150 patients showed exclusive extrapelvic tracer uptake, of which only 3 had vertebral metastatic disease. None of the patients with increased uptake exclusively in the extrapelvic-extraspinal location was metastatic. The incidence of exclusive extrapelvic skeletal metastatic disease in prostate carcinoma is 2% (excluding one patient with indeterminate findings). Further, none of the patients in the current study had exclusive extrapelvic-extraspinal metastasis. Thus, exclusive extrapelvic-extraspinal focal abnormality on planar BS carries a very low probability of metastatic disease and hence, further imaging or SPECT-CT can be safely avoided in such cases.

Quantitative assessment of cardiac 123iodo-metaiodobenzylguanidine SPECT/CT in patients with arrhythmogenic right ventricular cardiomyopathy: Novel insight in disease monitoring

BackgroundThe heart-to-mediastinum ratio (H/M-Ratio) of 123iodo-metaiodobenzylguanidine (123I-MIBG) represents state-of-the-art assessment for sympathetic dysfunction in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). This study aims to evaluate quantitative reconstruction of 123I-MIBG uptake and to demonstrate its correlation with echocardiographic parameters. MethodsCardiac innervation was assessed in 23 patients diagnosed with definite ARVC or borderline ARVC and 12 patients with other cardiac disease presenting arrhythmia, using quantitative 123I-MIBG Single Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) imaging. Tracer uptake was evaluated in the left (LV) and right ventricle (RV) based on a CT scan after quantitative image reconstruction. The relationship between tracer uptake and echocardiographic parameter data was examined. ResultsAbsolute quantification of 123I-MIBG uptake in the LV and RV is feasible and correlates accurately with the gold standard H/M Ratio. When comparing sensitivity and specificity, the area under the curve (AUC) favors standardized uptake value (SUV) of the RV over the right-ventricle-to-mediastinum-ratio (RV/M-Ratio) for diagnosing ARVC. A reduced RV-SUV in patients with definite ARVC is associated with reduced RV function. RV polar maps revealed globally reduced 123I-MIBG uptake without segment-specific reduction in the RV. ConclusionsQuantitative 123I-MIBG SPECT in ARCV patients offers robust potential for clinical reporting and demonstrates a significant correlation with RV function. Segmental RV analysis needs to be evaluated in larger samples. In summary, cardiac 123I-MIBG imaging using SUV could facilitate image-guided therapy in patients diagnosed with ARVC.

Novel evaluation of pulmonary hypertension associated with chronic lung disease using perfusion SPECT/CT: A pilot study.

In pulmonary hypertension (PH) associated with chronic lung disease (CLD), identifying patients who would benefit from pulmonary vasodilators is a significant clinical challenge because the presence of PH is associated with poorer survival. This study evaluated the severity of pulmonary circulation impairment in patients with CLD-PH using pulmonary perfusion single-photon emission computed tomography/computed tomography (SPECT/CT). This single-center, observational study enrolled patients with CLD-PH who had a mean pulmonary arterial pressure (PAP) ≥ 25 mmHg, as confirmed by right heart catheterization. The primary outcome was to measure the percentage of pulmonary perfusion defect (%PPD), calculated by dividing the perfusion defect volume from perfusion SPECT images by the lung volume from CT scan images. The secondary outcome was to assess the correlation between %PPD and baseline characteristics. The median %PPD was 52.4% (interquartile range, 42.5%-72.3%) in 22 patients. In multivariate linear regression analysis, both forced vital capacity (β = 0.58, p = 0.008) and mean PAP (β = 0.68, p = 0.001) were significantly correlated with %PPD. In conclusion, significant correlation between mean PAP and %PPD in patients with CLD-PH was observed. This noninvasive assessment of %PPD may be useful for evaluating the severity of pulmonary circulation impairment in CLD-PH.

Correlation between the maximum standard uptake value and mean Hounsfield unit on single-photon emission computed tomography-computed tomography to discriminate benign and metastatic lesions among patients with breast cancer.

Retrospective study. To compare and correlate technetium-99m methylene diphosphonate uptake between benign and metastatic bone lesions using semiquantitative analysis of maximum standard uptake value (SUVmax) and mean Hounsfield unit (HU) in single-photon emission computed tomography-computed tomography (SPECT-CT). Qualitative interpretation of metastatic bone lesions in breast cancer on bone scintigraphy is often complicated by coexisting benign lesions. In total, 185 lesions were identified on bone and SPECT-CT scans from 32 patients. Lesions were classified as metastatic (109 sclerotic lesions) and benign (76 lesions) morphologically on low-dose CT. Semiquantitative analysis using SUVmax and mean HU was performed on the lesions and compared. To discriminate benign and metastatic lesions, the correlation between SUVmax and mean HU was determined using the intraclass correlation coefficients. The SUVmax was higher in metastatic lesions (20.66±14.36) but lower in benign lesions (10.18±12.79) (p<0.001). The mean HU was lower in metastatic lesions (166.62±202.02) but higher in benign lesions (517.65±192.8) (p<0.001). A weak negative correlation was found between the SUVmax and the mean HU for benign lesions, and a weak positive correlation was noted between the SUVmax and the mean HU on malignant lesions with no statistical significance (p=0.394 and 0.312, respectively). The cutoff values obtained were 10.8 for SUVmax (82.6% sensitivity and 84.2% specificity) and 240.86 for the mean HU (98.7% sensitivity and 88.1% specificity) in differentiating benign from malignant bone lesions. Semiquantitative assessment using SUVmax and HU can complement qualitative analysis. Metastatic lesions had higher SUVmax but lower mean HU than benign lesions, whereas benign lesions demonstrated higher mean HU but lower SUVmax. A weak correlation was found between the SUVmax and the mean HU on malignant and benign lesions. Cutoff values of 10.8 for the SUVmax and 240.86 for the mean HU may differentiate bone metastases from benign lesions.

Sentinel Lymph Node Biopsy in Cutaneous Melanoma: Results of a Single-Center Analysis

Sentinel lymph node biopsy (SLNB) in cutaneous melanoma is a staging step in cases of unaffected regional lymph nodes. This method is included in routine practice in many medical facilities of the Russian Federation.Aim. To analyze the results of SLNB in cutaneous melanoma performed using gamma scintigraphy technique with the 99mTc-containing technefit radiopharmaceutical agent.Materials and methods. The prospective study included 97 patients (39.2 % (38/97) men and 60.8 % (59/97) women) with primary cutaneous melanoma who received surgical treatment at the Republican Clinical Oncological Dispensary (Ufa) between February of 2021 and January of 2023. Mean patient age was 57.2 ± 13.2 years (95 % confidence interval (CI) 53.8–61.3 years), mean Breslow thickness per biopsy and histological examination after wide tumor resection was 2.89 ± 2.7 mm (95 % CI 2.2–3.76 mm), median follow-up period was 14 months (interquartile range 8–18 months). 99mTc-containing technefit radiopharmaceutical agent was administered intradermally around melanoma/scar. Accumulation of the radiopharmaceutical in the regional lymph nodes was evaluated using single-photon emission computed tomography/computed tomography (SPECT/CT). Intraoperatively the sentinel lymph node (SLN) was identified using a portable gamma probe. Morphological evaluation was performed in accordance with the protocol approved at the Republican Clinical Oncological Dispensary and based on the updated protocol of the European Organisation for Research and Treatment of Cancer (EORTС) (2019).Results. The percentage of successfully mapped SLNs after radiopharmaceutical administration was 93.8 % (91/97). Mean number of visualized SLNs per SPECT/CT data was 1.7 ± 1.1 SLN (95 % CI 1.5–1.9). SLN biopsy was performed in 91.8 % (89/97) patients. Mean number of identified SLNs during SLNB was 1.9 ± 1.2 (95 % CI 1.6–2.3). Histological and immunohistochemical examinations showed SLN metastases in 22.5 % (20/89) patients; in 77.5 % (69/89) patients, no lymph node metastases were found. SLN biopsy allowed to perform disease staging. During follow-up in 3 patients with negative SLNs metastases in the regional lymph nodes were found, as well as in 2 patients with positive SLNs. The frequency of false negative SLNB results was 13 % (3/23), negative post-test probability was 2.8 % (2/69). V600E mutation in the BRAF gene was found in 42.3 % (22/52) patients.Conclusion. SLN biopsy using the technefit radiopharmaceutical showed satisfactory results: SLNs were identified in 93.8 % of cases. Morphological examination showed SLN metastases in 22.5 % (20/89) of patients.

Coronal Deformity is Associated With Uptake on Single Photon Emission Computed Tomography in Patients With Low Back Pain.

Retrospective Cohort Study. Single Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) is emerging as a valuable imaging test for identifying pain generators within the lumbar spine. The relationship between radiotracer uptake on SPECT/CT and anatomic biomechanical parameters has not been previously studied. We performed a retrospective review of all patients seen at our institution between 2021-2023 who obtained SPECT/CT scans for workup of thoracolumbar back pain. Patient data including demographic, clinical symptoms, and surgical history were collected. Radiology reports were reviewed for evidence of pathologic degeneration and increased bone metabolism on SPECT/CT. Biomechanical parameters were measured from standing scoliosis plain radiographs. Patients were stratified into two cohorts by either presence or absence of asymmetric coronal uptake on SPECT/CT. 160 patients met inclusion criteria. Patients were primarily male (55%) with average age 55 ± 15years. 87 (54%) patients demonstrated asymmetric uptake on SPECT/CT. These patients were older (P < 0.001), but with similar gender, prior fusion history, sacroiliitis, adjacent segment degeneration, and pseudoarthrosis (P > 0.05). This cohort had more disc disease, facet arthropathy, and greater degree of coronal scoliosis and coronal imbalance (P < 0.001). There were significantly more sites of uptake in the asymmetric cohort, and uptake was preferentially observed in the concavity of the lumbar curve (P < 0.001). There were no significant differences in sagittal balance or spinopelvic mismatch between cohorts (P > 0.05). Asymmetric uptake on SPECT/CT was associated with coronal deformity in patients with low back pain. Further prospective studies are warranted to assess the effect of coronal deformity on pain generation.