Whole-body Scan Research Articles

P-59 A CASE REPORT: A RARE CASE OF PAPILLARY THYROID CARCINOMA WITH BRAIN METASTASIS WITHOUT LOCAL RECURRENCE

Abstract Introduction Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy and generally has an excellent prognosis. However, distant metastases, particularly to the brain, are rare and associated with poor outcomes. This case report presents a 67-year-old female patient with a history of PTC, who developed brain metastasis in the follow-up. Clinical Case A 67-year-old female patient presented four years ago with a rapidly growing 4 cm mass, extending from the right thyroid gland to the right jugular vein. Fine-needle aspiration biopsy (FNAB) of the lesion was reported as suspicious for follicular neoplasm. Ultrasound imaging revealed pathological lymphadenopathy in the bilateral cervical chains. The patient underwent total thyroidectomy and bilateral neck dissection. Pathology confirmed the diagnosis of the follicular variant of papillary thyroid carcinoma (PTC), with extrathyroidal extension into muscle and adipose tissue, as well as lymph node metastases. After surgery, while the patient's TSH level was 68.6 µIU/ml, her thyroglobulin (Tg) level was 1.02 ng/ml, with negative anti-Tg antibodies. The patient received 150 mCi of radioactive iodine (RAI) approximately 3 months after surgery. One year after RAI therapy, a whole-body iodine scan showed no evidence of residual disease or metastasis. Follow-up Tg levels of the patient remained around 0.04 ng/ml. 3.5 years after surgery, there was a slight increase in thyroglobulin levels (0.26 ng/ml), although no recurrent disease was detected on ultrasound of the thyroid bed. The patient was planned to be under close surveillance but she did not come to visits regularly. The patient subsequently presented with complaints of imbalance and brain MRI revealed a mass lesion measuring 46x43x55 mm in the frontal region. The mass was surgically resected, and the pathology confirmed metastatic papillary thyroid carcinoma (PTC). A postoperative whole-body iodine scan was negative for metastatic disease. At that time, the TSH level was 0.5 µIU/ml, and thyroglobulin (Tg) was 0.04 ng/ml. Cranial radiotherapy was planned for the patient. Conclusion Approximately 10% of patients with PTC develop distant metastases, most commonly to the lungs and bones. Brain metastasis from PTC is extremely rare, occurring in less than 1% of cases. Due to its rarity, brain metastasis from PTC is not typically considered in the differential diagnosis for patients presenting with new neurological symptoms, potentially delaying diagnosis. Despite aggressive treatment, the prognosis for patients with PTC and brain metastasis remains poor, with a median survival of approximately 17 months. This case highlights the importance of considering the possibility of brain metastasis in high-risk PTC patients who present with neurological symptoms despite the lack of significant elevation in thyroglobulin (Tg) levels or evidence of recurrence on neck ultrasound.

P-62 A CASE OF PAPILLARY THYROID CARCINOMA WITH ISOLATED BONE METASTASES

Abstract Introduction Thyroid carcinomas constitute less than 3% of all cancers (1). Papillary thyroid carcinoma (PTC) accounts for 80% of thyroid carcinomas and generally has a good prognosis(2). Lymph node metastases are frequently observed in thyroid cancers(30-40%). However, distant metastases are quite rare(1-4%)(2). Clinical Case A 52-year-old female patient presented to the neurosurgery department due to back pain of approximately 2 months. A mass lesion was observed in the T9 vertebral body on a thoracic CT scan, which was destroying the bone structure, causing a compression fracture in the vertebra, and extending into the spinal canal. A total laminectomy of T9 vertebra and partial laminectomies of T8 and T10 vertebrae were performed. Pathology revealed strongly positive for Vimentin, TTF-1, Thyroglobulin, and Pax 8, consistent with carcinoma metastasis. It was recommended to perform a whole-body scan, primarily focusing on the thyroid gland. PET-CT, thoracic and abdominal CT scans revealed a 62x48 mm metastatic lesion in the right iliac bone and metastatic involvement of the T9 vertebra, with no other pathological findings. The patient's history revealed that she had undergone a total thyroidectomy six years ago, and the result was reported as benign. She was on levothyroxine sodium replacement therapy. Blood tests revealed TSH: 0.288 (0.27-4.2 µIU/ml), T4: 18.7 (12-22 pmol/L), T3: 4.78 (3.1-6.8 pmol/L), Anti-Thyroglobulin Antibody: 60.8 (0-115 IU/ml), and Thyroglobulin: >500 (3.5-77 ng/ml). Neck ultrasonography did not reveal any residual thyroid tissue or pathological lymph nodes. Given the suspicion of thyroid carcinoma metastasis and high thyroglobulin levels, the pathology preparations of the total thyroidectomy were re-consulted by our hospital's pathology department. The pathology result was consistent with papillary thyroid carcinoma composed of 55% follicular subtype and 45% solid/trabecular subtype. As surgery for the iliac bone metastasis was not considered appropriate, the patient was referred to the nuclear medicine department for radioactive iodine therapy and to the radiation oncology department for radiotherapy. The nuclear medicine, radiation oncology, and our department continue to follow up and treat the patient. Conclusion PTC is generally a slowly progressing cancer with a good prognosis. The most common site of metastasis in all PTC cases is the cervical lymph node, and only 3.5-3.8% have distant metastases(3). Distant metastases are most commonly seen in the lungs (53.4%), followed by bones (28.1%), liver (8.3%), and brain (4.7%) (1,4). Distant metastases significantly increase mortality from PTC. Therefore, the importance of adjuvant therapy (endocrine therapy, radiotherapy, etc.) and regular follow-up after thyroid cancer surgery should be emphasized. It should be kept in mind that, as in our case, papillary thyroid carcinomas can also present with isolated bone metastases without cervical lymph node metastases.

99mTc-FAPI-46 Scan and 177Lu-FAPI-2286 Treatment in a Patient With Nasopharyngeal Carcinoma.

We present a 24-year-old man with a history of metastatic nasopharyngeal cancer. Despite receiving standard treatments, including surgery, radiotherapy, and chemotherapy, he has shown progression. Consequently, he has been referred to the nuclear medicine department for theranostic purposes. The 99mTc-FAPI-46 whole-body scan showed tracer uptake in mediastinal large mass, both external lymph nodes and osseous metastases. Treatment with 177Lu-FAPI-2286 initiated, with subsequent planar scans revealing sustained uptake up to day 10, particularly in the large mediastinal mass. This case indicates promising FAPI-targeted theranostic potential in metastatic nasopharyngeal carcinoma and proper retention of 177Lu-FAPI-2286 in metastatic lesions.

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.

PET Imaging of Sphingosine-1-Phosphate Receptor 1 with [18F]TZ4877 in Nonhuman Primates.

The sphingosine-1-phosphate receptor-1 (S1PR1) is involved in regulating responses to neuroimmune stimuli. There is a need for S1PR1-specific radioligands with clinically suitable brain pharmcokinetic properties to complement existing radiotracers. This work evaluated a promising S1PR1 radiotracer, [18F]TZ4877, in nonhuman primates. [18F]TZ4877 was produced via nucleophilic substitution of tosylate precursor with K[18F]/F- followed by deprotection. Brain PET imaging data were acquired with a Focus220 scanner in two Macaca mulatta (6, 13 years old) for 120-180 min following bolus injection of 118-163 MBq [18F]TZ4877, with arterial blood sampling and metabolite analysis to measure the parent input function and plasma free fraction (fP). Each animal was scanned at baseline, 15-18 min after 0.047-0.063 mg/kg of the S1PR1 inhibitor ponesimod, 33 min after 0.4-0.8 mg/kg of the S1PR1-specific compound TZ82112, and 167-195 min after 1 ng/kg of the immune stimulus endotoxin. Kinetic analysis with metabolite-corrected input function was performed to estimate the free fraction corrected total distribution volume (VT/fP). Whole-body dosimetry scans were acquired in 2 animals (1M, 1F) with a Biograph Vision PET/CT System, and absorbed radiation dose estimates were calculated with OLINDA. [18F]TZ4877 exhibited fast kinetics that were described by the reversible 2-tissue compartment model. Baseline [18F]TZ4877 fP was low (<1%), and [18F]TZ4877 VT/fP values were 233-866 mL/cm3. TZ82112 dose-dependently reduced [18F]TZ4877 VT/fP, while ponesimod and endotoxin exhibited negligible effects on VT/fP, possibly due to scan timing relative to dosing. Dosimetry studies identified the critical organs of gallbladder (0.42 (M) and 0.31 (F) mSv/MBq) for anesthetized nonhuman primate. [18F]TZ4877 exhibits reversible kinetic properties, but the low fP value limits reproducible quantification with this radiotracer. S1PR1 is a compelling PET imaging target, and these data support pursuing alternative F-18 labeled radiotracers for potential future human studies.

Evaluating lower limits of body fat percentage in athletes using DXA.

Body fat percentage (BF%) is routinely measured in athletes to monitor training and dietary interventions. Dual energy x-ray absorptiometry (DXA) is widely considered the gold standard body composition measurement technique, but DXA BF% values measure consistently higher than other techniques. Therefore, the main purpose of this study is to determine the lowest DXA-estimated whole-body fat mass in free-living athletes with unrestricted access to food. In this cross-sectional analyses, 732 participants across 18 competitive sports (643 athletes; 88 %) plus two (male and female) "non-athlete" male and female cohorts (89 non-athletes; 12 %) underwent a whole-body DXA scan using a Horizon A Hologic™ device (software version 13.6.0.5; TBAR 1209), performed and analyzed by a single operator. The average BF % in 454 males (20.9 ± 3.8 years) was 18.2 ± 4.9 % (range 10.3 - 37.2 %), with basketball players having the lowest BF% (15.3 ± 2.6 %) and non-athletes having the highest BF% (21.6 ± 5.4 %) (1-way ANOVA between 10 teams: F = 12.3; p < 0.0001). The average BF% in 278 females (21.3 ± 5.5 years) was 27.1 ± 5.1 % (range 16.2 - 45.3 %), with runners having the lowest BF% (23.5 ± 3.5 %) and non-athletes having the highest BF% (31.7 ± 6.3 %) (1-way ANOVA between 10 teams F = 12.9; p < 0.0001). In absolute values (kg), the average body fat for males was 19.9 ± 8.0 kg (range 6.7 - 62.0 kg) and 18.9 ± 6.4 kg (range 9.2 - 49.7 kg) for females. These data suggest that the lower limits of whole-body fat mass in free-living competitive athletes is approximately 10 % for males and 16 % for females. Whether these DXA-derived fat thresholds represent "healthy" levels, or how much of these DXA-derived fat depots represent essential fat stores located within lean soft tissue mass, remains unclear.

Evaluation of a Deep Learning Denoising Algorithm for Dose Reduction in Whole-Body Photon-Counting CT Imaging: A Cadaveric Study.

Photon Counting CT (PCCT) offers advanced imaging capabilities with potential for substantial radiation dose reduction; however, achieving this without compromising image quality remains a challenge due to increased noise at lower doses. This study aims to evaluate the effectiveness of a deep learning (DL)-based denoising algorithm in maintaining diagnostic image quality in whole-body PCCT imaging at reduced radiation levels, using real intraindividual cadaveric scans. Twenty-four cadaveric human bodies underwent whole-body CT scans on a PCCT scanner (NAEOTOM Alpha, Siemens Healthineers) at four different dose levels (100%, 50%, 25%, and 10% mAs). Each scan was reconstructed using both ADMIRE level 2 and a DL algorithm (ClariCT.AI, ClariPi Inc.), resulting in 192 datasets. Objective image quality was assessed by measuring CT value stability, image noise, and contrast-to-noise ratio (CNR) across consistent regions of interest (ROIs) in the liver parenchyma. Two radiologists independently evaluated subjective image quality based on overall image clarity, sharpness, and contrast. Inter-rater agreement was determined using Spearman's correlation coefficient, and statistical analysis included mixed-effects modeling to assess objective and subjective image quality. Objective analysis showed that the DL denoising algorithm did not significantly alter CT values (p ≥ 0.9975). Noise levels were consistently lower in denoised datasets compared to the Original (p < 0.0001). No significant differences were observed between the 25% mAs denoised and the 100% mAs original datasets in terms of noise and CNR (p ≥ 0.7870). Subjective analysis revealed strong inter-rater agreement (r ≥ 0.78), with the 50% mAs denoised datasets rated superior to the 100% mAs original datasets (p < 0.0001) and no significant differences detected between the 25% mAs denoised and 100% mAs original datasets (p ≥ 0.9436). The DL denoising algorithm maintains image quality in PCCT imaging while enabling up to a 75% reduction in radiation dose. This approach offers a promising method for reducing radiation exposure in clinical PCCT without compromising diagnostic quality.

Radiographic, computed tomographic, and histologic characteristics of bone for clinically normal laying hens in a free-range housing system.

Laying hens are increasingly being kept in backyard flocks and considered family pets; however, diagnostic imaging characteristics of bone for clinically normal backyard hens are currently limited. This prospective, descriptive study was to describe radiographic, computed tomographic, and histologic characteristics of bone for a group of clinically normal laying hens housed in conditions comparable to those of backyard flocks. Sixteen 60-week-old Lohmann Brown laying hens were included. Hens were housed in a free-range unit with outdoor access at a university research and teaching farm. Hens were defined as clinically normal by the farm manager and a veterinary researcher in laying hen behavior and welfare. Findings from the horizontal beam, left lateral, sternal radiographs (n=16), postmortem, and whole-body CT scans (n=4) were recorded by a veterinary radiologist and a research technician. Histologic findings for sternal, femoral, and tibiotarsal bone samples (n=5) were recorded by a veterinary pathologist. The most frequent radiographic findings for the sternal carina (keel bone) were smoothly marginated concave deviations of the ventral margin and caudal section fractures. Multiple punctate mineral opacities (PMOs) were present in radiographs and CT images for all hens and were involved in the sternal carina and multiple other bones in the axial and appendicular skeleton. No bone abnormalities were identified in any histologic sections where PMOs were radiographically detected. Authors propose that PMOs are normal radiographic and CT findings in the bones of mature, laying hens and may represent temporary calcium reservoirs formed during osteoclastic activities.

Validation of a 3D whole-body scanning system to collect anthropometric data from a working-age population for ergonomic design

Validation of a 3D whole-body scanning system to collect anthropometric data from a working-age population for ergonomic design

18F]Tetrafluoroborate: a new NIS PET/CT radiopharmaceutical. An overview focused on differentiated thyroid cancer.

In relapsing differentiated thyroid cancer (DTC), the in vivo evaluation of natrium-iodine symporter (NIS) expression is pivotal in the therapeutic planning and is achieved by [131/123I]Iodine whole-body scan. However, these approaches have low sensitivity due to the low sensitivity due to the low resolution of SPECT. [18F]Tetrafluoroborate (TFB) has been proposed as a viable alternative, which could outperform [131/123I]Iodine scans owing to the superior PET resolution. We have reviewed the literature to collect the available data on TFB diagnostic performance and compare it with standard methods. Two authors searched PubMed, CENTRAL, Scopus, Web of Science and the web for studies evaluating the biodistribution and dosimetry of TFB in patients with DTC. General characteristics, technical parameters, procedures' sensitivities, and standards-of-reference were extracted from the selected studies. The risk of bias was evaluated with the QUADAS-2 scoring system. Five studies were included in the review. Two analysed TFB's biodistribution and dosimetry, while the other three assessed its diagnostic performance. The diagnostic comparators were [18F]FDG-PET/CT (all cases), [124I]Iodine-PET/CT (one study), and diagnostic/therapeutic [131I]Iodine-SPECT/CT (one study each). TFB performed better than [131I]Iodine; the TFB and [18F]FDG-PET/CT combination achieved the best sensitivity. TFB delivered significantly less dose than the other NIS tracers. TFB is a promising tracer in relapsing DTC, showing higher sensitivity and less radiation exposure than standard methods. The TFB and [18F]FDG combination appears particularly intriguing, especially when disease heterogeneity is suspected. However, data are still sparse and need to be confirmed by further investigations.

A case and review of FGF23-mediated hypophosphatemic osteomalacia in the absence of pathogenic PHEX variants

Abstract We report an atypical case of fibroblast growth factor-23 (FGF23)-mediated hypophosphatemic osteomalacia without a pathogenic variant (PV) of PHEX, who improved biochemically, clinically and radiologically post burosumab treatment. We present a narrative review of FGF23-mediated hypophosphatemic osteomalacia and propose a roadmap for investigating the etiology of hypophosphatemia to guide therapy. A 29-year-old female with FGF23-mediated hypophosphatemic osteomalacia experienced multiple insufficiency fractures, including bilateral femoral diaphyseal fractures and delayed healing. This occurred on a background of juvenile enthesitis-related arthritis, narcolepsy and brittle dentition since her early teens. Whole-body magnetic resonance imaging and Gallium-68 DOTATATE positron emission tomography scans were unremarkable, making tumor-induced osteomalacia highly unlikely. No hypophosphatemic PVs were found using massively parallel sequencing. Despite phosphate and calcitriol therapy, mild hypophosphatemia persisted with minimal improvement in fracture healing or pain. One dose of 60 mg burosumab, an anti-FGF23 antibody, led to hyperphosphatemia requiring dose titration and three doses of burosumab normalized renal tubular maximum reabsorption rate of phosphate relative to glomerular filtration rate. Burosumab led to fracture healing with callus formation corresponding with improved pain at fracture sites. Hypophosphatemic osteomalacia manifests with varus deformity of the lower limbs, gait disturbance, muscle weakness, enthesopathy, and dental necrosis. Evaluation of the etiology is crucial and requires an algorithmic approach to determine whether hypophosphatemia is renally-mediated, FGF23-mediated, acquired or inherited. The most common inherited cause of FGF23-mediated hypophosphatemic osteomalacia is X-linked hypophosphatemia (XLH) secondary to a PV of the PHEX gene. However, the absence of a PHEX PVs does not exclude a diagnosis of hereditary FGF23-mediated hypophosphatemic osteomalacia. Other inherited causes of this disorder include autosomal dominant and autosomal recessive hypophosphatemic rickets, fibrous dysplasia-McCune-Albright syndrome, cutaneous skeletal hypophosphatemia syndrome and osteoglophonic dysplasia. Burosumab significantly improves serum phosphate and fracture healing in XLH and may effectively treat other forms of FGF23-mediated hypophosphatemia.

The role of sympathetic control in bone vasculature: insights from spinal cord injury.

Bone vasculature is richly innervated by an extensive network of sympathetic nerves. However, our understanding of bone blood flow regulation and its contribution to human bone health is limited. Here, we further our previous findings by characterizing bone vascular responses in the absence of sympathetic control - studying individuals with spinal cord injury (SCI), a population with known peripheral sympathetic disruption. We assessed tibial vascular responses to isometric handgrip exercise (IHE) in individuals with SCI (n = 12) and controls (n = 12). When sustained to fatigue, IHE increases perfusion pressure and sympathetic vasoconstriction in the non-active tissues of the legs. During IHE, we measured blood pressure, whole leg blood velocity via ultrasound, and tibial perfusion (as hemoglobin content) via near-infrared spectroscopy. Controls demonstrated active sympathetic vasoconstriction in the whole leg (i.e., increased vascular resistance, arterial pressure/leg blood velocity) and tibia (i.e., decreased hemoglobin). In contrast, SCI individuals demonstrated modest whole leg vasoconstriction with lesser increases in vascular resistance than controls (P<.04). Tibial vasculature evidenced absent or blunted vasoconstriction compared to controls (P<.01), indicated by increasing tibial hemoglobin until plateauing at higher pressure levels. This suggests that, in the absence of sympathetic control, tibial vascular response may involve other regulatory mechanisms like myogenic vasoconstriction. Lastly, we leveraged existent whole-body Dual Energy X-ray Absorptiometry scans in a subgroup of nine individuals with SCI and we found a strong relationship between leg bone mineral density (BMD) and tibial hemoglobin at end of IHE (r2 = 0.67, P<.01). Our findings indicate that in the absence of sympathetic mechanisms, myogenic control may play a compensatory role in regulating blood flow, though to a lesser extent in bone compared to muscle. The close relationship between lesser declines in bone blood content and higher BMD underscores the link between blood flow and bone health.

Evaluation of the safety, biodistribution, dosimetry of [18F]AlF-NYM005 and initial experience in clear cell renal cell carcinoma: an interim analysis of a prospective trial.

This first-in-human study aimed to evaluate the radiation dosimetry and whole-body biodistribution of [18F]AlF-NYM005, a novel small-molecule carbonic anhydrase IX (CAIX) targeting agent, and to investigate its ability to detect CAIX-positive tumors using PET scans in a cohort of clear cell renal cell carcinoma (ccRCC) patients. [18F]AlF-NYM005 was synthesized using a fully automatic cassette module Mortenon M1 (Nuoyu, China). Thirty-five patients with a suspicious lesion considered primary renal malignancy or a history of ccRCC were prospectively recruited and studied. All patients underwent [18F]AlF-NYM005 PET/CT examinations and the maximum standardized uptake value (SUVmax) was measured on conventional [18F]AlF-NYM005 PET/CT images. Among these patients, five patients underwent dynamic [18F]AlF-NYM005 PET/CT scanning (120min) of the lower abdomen. Another subset of five ccRCC patients underwent sequential whole-body PET scans at 30, 60, 90, and 120min (one of the five patients underwent additional 150min and 180min scans) after [18F]AlF-NYM005 injection to assess biodistribution and dosimetry. The influx constant (Ki) was calculated from the dynamic [18F]AlF-NYM005 PET/CT data using the Patlak model. Whole-body biodistribution was calculated as time-activity curves (TACs) describing dynamic uptake patterns in the patients' major organs, followed by calculation of tracer kinetics and cumulative organ activity. Effective doses of [18F]AlF-NYM005 and individual organ doses were also calculated. [18F]AlF-NYM005 was successfully synthesized with a radiochemical purity of > 95% and an average labeling yield of 36.5 ± 8.3%. All patients tolerated the PET examinations well, and no adverse side effects were observed. The total body effective dose was 7.6E-03 mSv/MBq. The highest agent uptake was observed in the kidneys, stomach, and liver, contributing to an effective dose of 0.0126 ± 0.0029 mSv/MBq. The TACs showed optimal normal organ uptake with high tumor uptake and long retention of up to 2h post-injection. Notably, a rapid increase of the tracer followed by a rapid decrease in the blood pool, kidney, liver, and tumor lesions was observed, indicating that [18F]AlF-NYM005 was rapidly eliminated from blood and urine. For the kinetic data analysis, the Ki for the primary kidney lesions had a mean of 0.082 ± 0.057ml/g/min. The CAIX-positive tumors displayed rapid uptake, and all lesions were detectable within 30min, with no additional lesions observed in the subsequent multi-time point scans. The patient-level sensitivity, specificity, and accuracy of [18F]AlF-NYM005 PET/CT were 93.8%, 75.0%, and 90% for group 1 and 92.3%, 100%, and 93.3% for group 2, respectively. For per-lymph node analysis, [18F]AlF-NYM005 PET/CT demonstrated 92.9% sensitivity, 90.5% specificity, and 91.8% accuracy in diagnosing metastatic lymph nodes. For per-distant metastasis analysis, it showed 90.5% sensitivity, 91.3% specificity, and 90.6% accuracy. The SUVmax of [18F]AlF-NYM005 PET/CT for primary ccRCC lesions was 15.5 ± 7.35. Tumor uptake was positive correlated with immunohistochemical staining findings. This pilot study in ccRCC patients has demonstrated the safety, acceptable radiation dosimetry, favorable biodistribution, and exceptional tumor uptake of [18F]AlF-NYM005. The preliminary diagnostic study indicated the potential utility of [18F]AlF-NYM005 PET/CT, showing promising results in the diagnosis of primary or metastatic ccRCC. This study was registered at ClinicalTrial.gov (ChiCTR2200058108) as NYPILOT on 29 March, 2022.

Uterine artery projection relative to anatomical bony landmarks in CT-angiographies.

The aim was to find bony landmarks of the pelvis for the origins and routes of uterine arteries, hoping to improve speed and safety of embolization procedures (leiomyoma, post-partum bleedings…). We carried out a study based on the analysis of CT-angiographies in arterial phases of whole-body scans. Two measurements were done per artery, one from the origin of uterine arteries to a first perpendicular line passing through the lowest part of the sacroiliac joint, another one from the beginning of the parametrial segment from a second parallel line passing by the acetabular roof. Mean distances across all these measurements were calculated, as were potential associations with known variables such as anatomical variants, age, parity and any pelvic surgical history. Two hundred uterine arteries were analyzed. Concerning the origin, 83.5% of uterine arteries were located approximately one centimeter around the first line defined above, with a mean distance of + 4.8mm. Concerning parametrial segment beginning, 88% were located approximately one centimeter around the second line defined, with a mean distance of only + 3.9mm above the acetabular roof. Some significant differences were observed in subgroups, notably with a small trend to higher arising of uterine arteries in patients who had at least one childbirth, and expectedly lower arising in distal anatomical variants. Clear pelvic anatomic landmarks exist and could help the guidance of arteries catheterization, and therefore indirectly lead to faster embolization and optimize procedures safety.

18F]SF51, a novel 18F-labeled PET radioligand for translocator protein 18kDa (TSPO) in brain, works well in monkeys but fails in humans.

[18F]SF51 is a novel radioligand for imaging translocator protein 18 kDa (TSPO) that previously displayed excellent imaging properties in nonhuman primates. This study assessed its performance in human brain and its dosimetry. Seven healthy participants underwent brain PET imaging to measure TSPO binding using a two-tissue compartment model (2TCM) to calculate total distribution volume (VT). This cohort included two high-affinity binders (HABs), three mixed-affinity binders (MABs), and two low-affinity binders (LABs). Two other participants received whole-body scans to assess radiation exposure. Peak brain radioactivity reached a standardized uptake value (SUV) of 1.4 at 3 minutes post-injection, diminishing to 30% of peak by 120 minutes. The average VT for all genotype groups was notably low (<1 mL·cm-3), emphasizing the radioligand's poor binding in brain. [18F]SF51 remained sensitive to the TSPO polymorphism in vivo, as shown by a two-fold difference in VT between HABs and LABs. VT stabilization by 80 minutes post-injection suggested minimal radiometabolite accumulation in brain. The average effective dose was 13.8 ± 0.9 µSv/MBq. Contrary to previously published animal data, [18F]SF51 showed low binding to human TSPO, with uptake remaining influenced by the rs6971 polymorphism. These findings highlight the challenges of developing TSPO radioligands and underscore the significant species differences that may influence translational outcomes.ClinicalTrials.gov identifier: NCT05564429; registered 10/03/2022.

Superscan in First Posttherapeutic 177Lu-PSMA Scan.

This case highlights the effectiveness of 177Lu-PSMA therapy in a 70-year-old man with castration-resistant prostate cancer who has extensive skeletal metastases in posttherapeutic whole-body imaging. A 70-year-old man with extensive skeletal metastases underwent 4 cycles of 177 Lu-PSMA-617 therapy. A whole-body 177Lu-PSMA scan after the first cycle showed diffuse skeletal lesions, with minimal PSMA uptake in the kidneys and salivary glands. A whole-body scan after the fourth cycle of 177Lu-PSMA showed a complete response of skeletal metastases with normal PSMA uptake in the kidneys and salivary glands. According to RECİP 1.0, the patient was considered a complete response.

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.

Assessing radiation exposure of fingers of PET/CT technologists during 18F-FDG procedures using active extremity dosimeters: a single-center study

Extremity radiation exposure in nuclear medicine is a growing concern because it may surpass the maximum permissible dose of 500 mSv. This study aimed to assess the occupational finger dose received by technologists during the preparation and administration of18F-FDG radiopharmaceuticals in positron emission tomography-computed tomography (PET-CT) whole-body scan procedures. Fifty scans were selected, with one procedure excluded due to a high administered activity. The mean administered activity per scan was 207.2 ± 41.8 MBq, with preparation and administration times averaging 1.44 ± 1.30 min and 0.46 ± 0.31 min, respectively. The technologist's mean total finger dose received during preparation and administration was 253.5 ± 153.3 µSv per procedure. A significant positive correlation was found between the administered activity and occupational dose, with patient's body mass index, preparation time, and administration time also contributing to dose variation. Based on 703 PET-CT procedures conducted in 2022, the estimated occupational finger dose for a technologist was 178.2 mSv annually. This value is well below the International Commission on Radiological Protection's maximum permissible dose of 500 mSv. The findings of this study have a significant impact on extremity dosimetry in nuclear medicine in Sri Lanka, as this is the first study of its kind.

PET/MRI evaluation of hepatobiliary tumors.

Positron-emission tomography magnetic resonance imaging (PET/MRI) has emerged as a powerful hybrid molecular imaging technique in clinical practice, overcoming initial technical challenges to provide comprehensive anatomic and metabolic information. This advanced modality combines the superior soft tissue contrast of MRI with the metabolic insights of PET, offering advantages in hepatobiliary imaging, including improved detection of small liver metastases and reduced radiation exposure. The evolution of PET/MRI technology has been marked by significant advancements, such as the development of MRI-compatible PET detectors and sophisticated motion compensation techniques. These innovations have enhanced image quality and co-registration accuracy, crucial for hepatobiliary imaging. The integration of time-of-flight capability and silicon photomultipliers has further improved spatial resolution and sensitivity. PET/MRI protocols for liver imaging typically involve a whole-body scan followed by a targeted liver examination, utilizing radiotracers like FDG and DOTATATE. This approach allows for comprehensive staging and detailed liver assessment in a single session, potentially altering management decisions in up to 30% of patients with intrahepatic cholangiocarcinoma. While PET/MRI excels in characterizing various hepatobiliary lesions, including hepatocellular carcinoma and cholangiocarcinoma, challenges remain in differentiating certain benign entities like small hemangiomas from metastases. Ongoing research and clinical experience continue to refine the role of PET/MRI in hepatobiliary imaging, promising improved diagnostic accuracy and patient care.

Diagnostic performance of fluorine-18-fluorodeoxyglucose PET/MRI for detection of disease recurrence in differentiated thyroid cancer: a compartment-based analysis.

The objective of this study is to evaluate the diagnostic performance of neck fluorodeoxyglucose (FDG) PET/MRI in addition to whole-body PET/computed tomography (CT) and to compare it with MRI in the detection of suspicion of disease relapse in patients with differentiated thyroid cancer (DTC) who underwent total thyroidectomy and radioactive iodine therapy. Twenty-nine patients with DTC who underwent whole-body 18F-FDG PET/CT followed by neck PET/MRI because of increased serum thyroglobulin (Tg) or anti-Tg antibody levels and negative 131I whole-body scan were included. At least 6 months of clinical and radiological (neck ultrasound) follow-up or histopathological examination results were accepted as the gold standard. Lesion and compartment-based analyses were performed to evaluate the diagnostic performances of PET/CT, MRI, and PET/MRI. In addition, changes of clinical management were evaluated. On lesion-based analysis, for PET/CT, MRI, and PET/MRI: sensitivity: 33.3, 33.3, and 37%; specificity: 90.1, 87.9, and 95.9%; accuracy: 87.5, 85.4, and 93.2 were calculated, respectively. Specificity of PET/MRI was significantly superior to PET/CT and MRI (P of0.001); however, sensitivity of PET/MRI was not significant to PET/CT and MRI (P of0.05). On compartment-based analysis, specificity of PET/MRI and MRI were comparable but significantly superior to PET/CT at levels 1 and 2; however, specificity of PET/CT and PET/MRI were comparable but significantly superior than MRI, especially at levels 3, 4, and 5. PET/MRI especially helps in the accurate exclusion of findings that are suspicious on PET/CT and MRI, and has the potential to change the clinical management by identifying uncertain neck findings.