Coronary microvascular dysfunction as assessed by multimodal diagnostic imaging in patients with hypertrophic cardiomyopathy is related to the severity of cardiac dysfunction.

INTRODUCTION: Coronary microvascular dysfunction (CMD) plays a major role in hypertrophic cardiomyopathy (HCM) physiopathology but its assessment in clinical practice remains a challenge. Nowadays, innovations in invasive and noninvasive coronary evaluation using multimodal imaging provide options for the diagnosis of CMD. The objective of the present study was to investigate if new multimodal imaging diagnosis of CMD could detect HCM patients with more impaired cardiac function by left atrioventricular coupling index (LACI). METHODS AND RESULTS: A total of 32 consecutive patients with a confirmed diagnosis of HCM (62 ± 13 years, 62% men) were prospectively screened for CMD using a multimodal imaging method. LACI was assessed by cardiovascular magnetic resonance imaging. Fifteen (47%) patients had CMD by multimodal imaging method. Patients with CMD presented a significantly higher LACI (48.5 ± 25.4 vs. 32.5 ± 10.6, p = .03). A multivariate logistic regression analysis demonstrated that CMD was independently associated with LACI (OR = 1.069, 95% CI 1.00-1.135, p = .03). CONCLUSION: Multimodal imaging diagnosis of CMD is applicable to HCM patients and is associated with more impaired cardiac function.

Response Evaluation Criteria in PSMA PET/CT (RECIP 1.0) in Metastatic Castration-resistant Prostate Cancer.

Background Response Evaluation Criteria in Prostate-specific Membrane Antigen (PSMA) PET/CT (RECIP 1.0) initially integrated software-based quantitative assessment of PSMA-positive total tumor volume (TTV). Clinical implementation of such software is not expected soon, limiting the use of RECIP in practice. Purpose To assess the agreement of RECIP determined using tumor segmentation software (quantitative RECIP) with RECIP determined by qualitative reads by nuclear medicine physicians (visual RECIP) for response evaluation in metastatic castration-resistant prostate cancer. Materials and Methods This multicenter retrospective study at three academic centers included men who received lutetium 177 (177Lu) PSMA treatment between December 2014 and July 2019. PSMA PET/CT images at baseline and 12 weeks were assessed qualitatively by five readers for changes in TTV and for new lesions. Quantitative changes in TTV were also measured using tumor segmentation software. The status of new lesions was combined with qualitative changes in TTV to determine visual RECIP and with quantitative changes in TTV to determine quantitative RECIP. The primary outcomes were the agreement between visual and quantitative RECIP and the interreader reliability of visual RECIP according to the Fleiss κ. The secondary outcome was the association of visual RECIP with overall survival according to Cox regression. Results A total of 124 men (median age, 73 years [IQR, 67-76 years]) were included. Forty (32%) and 84 (68%) men had quantitative RECIP progressive disease (PD) and non-PD, respectively. Agreement between visual versus quantitative RECIP was excellent (κ = 0.89; 118 of 124 men [95%]). Agreement among readers in classifying visual RECIP PD versus non-PD was excellent (κ = 0.81; 103 of 124 men [83%]). RECIP PD was associated with significantly shorter overall survival compared with non-PD (hazard ratio, 2.6 [95% CI: 1.7, 3.8]; P < .001). Conclusion Qualitatively assessed RECIP demonstrated excellent agreement with quantitative RECIP and excellent interreader reliability and can be readily implemented in clinical practice for response evaluation in men with metastatic castration-resistant prostate cancer undergoing 177Lu-PSMA therapy. © RSNA, 2023 Supplemental material is available for this article.

Regional CZT myocardial perfusion reserve for the detection of territories with simultaneously impaired CFR and IMR in patients without obstructive coronary artery disease: a pilot study.

OBJECTIVES: To assess the diagnostic performances of CZT myocardial perfusion reserve (MPR) for the detection of territories with simultaneous impaired coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) in patients without obstructive coronary artery disease. METHODS: Patients were prospectively included before being referred for coronary angiography. All patients underwent CZT MPR before invasive coronary angiography (ICA) and coronary physiology assessment. Rest and dipyridamole-induced stress myocardial blood flow (MBF) and MPR were quantified using 99mTc-SestaMIBI and a CZT camera. Fractional flow reserve (FFR), Thermodilution CFR, and IMR were assessed during ICA. RESULTS: Between December 2016 and July 2019, 36 patients were included. 25/36 patients presented no obstructive coronary artery disease. A complete functional assessment was performed in 32 arteries. No territory presented a significant ischemia on CZT myocardial perfusion imaging. A moderate yet significant correlation was observed between regional CZT MPR and CFR (r = 0.4, P = .03). Sensitivity, specificity, positive and negative predictive value, and accuracy of regional CZT MPR versus the composite invasive criterion (impaired CFR and IMR) were 87 [47% to 99%], 92% [73% to 99%], 78% [47% to 93%], 96% [78% to 99%], and 91% [75% to 98%], respectively. All territories with a regional CZT MPR ≤ 1.8 showed a CFR < 2. Regional CZT MPR values were significantly higher in arteries with CFR ≥ 2 and IMR < 25 (negative composite criterion, n = 14) than in those with CFR < 2 and IMR ≥ 25 (2.6 [2.1 to 3.6] versus 1.6 [1.2 to 1.8]), P < .01). CONCLUSION: Regional CZT MPR presented excellent diagnostic performances for the detection of territories with simultaneously impaired CFR and IMR reflecting a very high cardiovascular risk in patients without obstructive coronary artery disease.

Coronary Physiology: Delivering Precision Medicine?

Coronary physiological assessment is now widely used to assess epicardial coronary lesions in cath lab. Based on clinical evidence, fractional flow reserve (FFR) is the gold standard method to select whether epicardial coronary lesions need revascularization. While additional epicardial indexes, such as instantaneous wave-free ratio (iFR), are also used for revascularization decision-making, several indexes are now also available to explore the coronary microcirculation. Therefore, coronary physiological assessment now allows to explore the entire coronary tree and offer the potential of precision medicine for patients affected by coronary artery disease (CAD). This paper will provide review of the epicardial and microvascular indexes available for the assessment of coronary physiology. More specifically, the already demonstrated contributions of these indexes in the management of CAD and the role they could play in precision medicine will be reviewed with special emphasis on chronic coronary syndrome.

Comparison of Cadmium Zinc Telluride ECG-gated SPECT equilibrium radionuclide angiocardiography to magnetic resonance imaging to measure right ventricular volumes and ejection fraction in patients with cardiomyopathy.

AIMS: The objective of this study was to determine the accuracy of right ventricular function (RVF) assessed by Cadmium Zinc Telluride ECG-gated SPECT equilibrium radionuclide angiocardiography (CZT-ERNA). METHODS AND RESULTS: Twenty-one consecutive patients with cardiomyopathy (aged 54 ± 19 years; 62% male) were included. RV ejection fraction (EF) and volumes were analyzed by CZT-ERNA and compared with values obtained by cardiac magnetic resonance imaging (CMR). Mean values were not different between CZT-ERNA and MRI for RVEF (48.1 ± 10.4% vs 50.8 ± 10.0%; P = .23). Significant correlations (P < .0001) were observed between CZT-ERNA and MRI for RVEF, RV end-diastolic volume, and end-systolic volume (r = 0.81, r = 0.93, and r = 0.96, respectively). Bland-Altman analysis showed a mean difference (bias) between CZT-ERNA and MRI for RVEF of -2.69% (95% CI - 5.35 to - 0.42) with good agreement between the 2 techniques (limits of agreement, -14.3 to 8.99). Intraobserver and interobserver reproducibility of RVF measured by CZT-ERNA was high. CONCLUSION: CZT-ERNA provides accurate, reproducible assessment of RVF and appears as a good alternative to cardiac magnetic resonance for the evaluation of the magnitude of RVF in patients with cardiomyopathy.

Preclinical and clinical evaluation of a new method to assess cardiac insulin resistance using nuclear imaging.

BACKGROUND: Myocardial insulin resistance (IR) could be a predictive factor of cardiovascular events. This study aimed to introduce a new method using 123I-6-deoxy-6-iodo-D-glucose (6DIG), a pure tracer of glucose transport, for the assessment of IR using cardiac dynamic nuclear imaging. METHODS: The protocol evaluated first in rat-models consisted in two 6DIG injections and one of insulin associated with planar imaging and blood sampling. Compartmental modeling was used to analyze 6DIG kinetics in basal and insulin conditions and to obtain an index of IR. As a part of a translational approach, a clinical study was then performed in 5 healthy and 6 diabetic volunteers. RESULTS: In rodent models, the method revealed reproducible when performed twice at 7 days apart in the same animal. Rosiglitazone, an insulin-sensitizing drug, induced a significant increase of myocardial IR index in obese Zucker rats from 0.96 ± 0.18 to 2.26 ± 0.44 (P<.05) after 7 days of an oral treatment, and 6DIG IR indexes correlated with the gold standard IR index obtained through the hyperinsulinemic-euglycemic clamp (r=.68, P<.02). In human, a factorial analysis was applied on images to obtain vascular and myocardial kinetics before compartmental modeling. 1.5-fold to 2.2-fold decreases in mean cardiac IR indexes from healthy to diabetic volunteers were observed without reaching statistical significance. CONCLUSIONS: These preclinical results demonstrate the reproducibility and sensibility of this novel imaging methodology. Although this first in-human study showed that this new method could be rapidly performed, larger studies need to be planned in order to confirm its performance.

Prognostic value of SPECT myocardial perfusion entropy in high-risk type 2 diabetic patients.

PURPOSE: Risk stratification of patients with type 2 diabetes mellitus (T2D) remains suboptimal. We hypothesized that myocardial perfusion entropy (MPE) quantified from SPECT myocardial perfusion images may provide incremental prognostic value in T2D patients independently from myocardial ischemia. METHODS: T2D patients with very high and high cardiovascular risk were prospectively included (n = 166, 65 ± 12 years). Stress perfusion defect was quantified by visual evaluation of SPECT MPI. SPECT MPI was also used for the quantification of rest and stress MPE. The primary end point was major adverse cardiac events (MACEs) defined as cardiac death, myocardial infarction (MI), and myocardial revascularization > 3 months after SPECT. RESULTS: Forty-four MACEs were observed during a 4.6-year median follow-up. Significant differences in stress MPE were observed between patients with and without MACEs (4.19 ± 0.46 vs. 3.93 ± 0.40; P ≤ .01). By Kaplan-Meier analysis, the risk of MACEs was significantly higher in patients with higher stress MPE (log-rank P ≤ 01). Stress MPE and stress perfusion defect (SSS ≥ 4) were significantly associated with the risk of MACEs (hazard ratio 2.77 and 2.06, respectively, P < .05 for both) after adjustment for clinical and imaging risk predictors as identified from preliminary univariate analysis. MPE demonstrated incremental prognostic value over clinical risk factors, stress test EKG and SSS as evidenced by nested models showing improved Akaike information criterion (AIC), reclassification (global continuous net reclassification improvement [NRI]: 63), global integrated discrimination improvement (IDI: 6%), and discrimination (change in c-statistic: 0.66 vs 0.74). CONCLUSIONS: Stress MPE provided independent and incremental prognostic information for the prediction of MACEs in diabetic patients. TRIAL REGISTRATION NUMBER: NCT02316054 (12/12/2014).

Prospective diagnostic performance of semiconductor SPECT myocardial perfusion imaging: wall thickening analysis reduces the need for an additional prone acquisition.

PURPOSE: To determine whether the assessment of regional wall thickening (WT) in addition to myocardial perfusion from stress supine acquisitions could compensate for the lack of prone acquisition and the corresponding decrease in the diagnostic performance of SPECT myocardial perfusion imaging (MPI) in patients with known or suspected coronary artery disease (CAD). METHODS: The study group comprised 41 patients (123 vessels) with known or suspected CAD prospectively recruited for systematic prone and supine 201Tl stress SPECT MPI. The diagnostic performance of SPECT MPI was determined for various image sets including nongated supine images (supine NG), nongated combined prone and supine images (prone and supine NG) and gated supine images, allowing WT evaluation from NG images in addition to perfusion (supine NG + WT) using invasive coronary angiography and fractional flow reserve as the gold standards. RESULTS: The rate of false positives was significantly higher among the supine NG images (20.8%) than among either the prone and supine NG or the supine NG + WT images (3.3% and 2.7%, respectively, P < 0.05 vs. supine NG). Consequently, specificity was higher for the prone and supine NG images than for the supine NG images (96.1% vs. 76.1%, P < 0.01) and was highest for the supine NG + WT images (96.8%, P not significant vs. prone and supine NG), without significant differences in sensitivity (80.0%, 86.6% and 73.3%, respectively, P not significant for all comparisons). CONCLUSION: The diagnostic performance of supine stress SPECT MPI is improved when WT assessment of ischaemic segments is used as an additional diagnostic criterion to values not significantly different from those with combined prone and supine acquisitions.

Diagnostic value of stress thallium-201/rest technetium-99m-sestamibi sequential dual isotope high-speed myocardial perfusion imaging for the detection of haemodynamically relevant coronary artery stenosis.

BACKGROUND: The aim of this study was to determine the diagnostic accuracy of stress thallium-201/rest technetium-99m-sestamibi sequential dual-isotope high-speed myocardial perfusion imaging (DI-HS-MPI) against invasively determined fractional flow reserve (FFR). METHODS: Fifty-four consecutive patients prospectively underwent DI-HS-MPI before invasive coronary angiography. Perfusion was scored visually by summed stress score on a patient and coronary territory basis. Significant coronary artery disease (CAD) was defined by the presence of ≥ 90% stenosis/occlusion or fractional flow reserve ≤ 0.80 for coronary stenosis ≥ 50%. RESULTS: FFR was measured in 69 of 162 coronary vessels, with 1.28 ± 0.56 vessels assessed/patient. Sensitivity, specificity, and diagnostic accuracy of MPI for the detection of significant CAD were 92.8%, 69.2%, and 81.4%, on a patient basis, and 83.7%, 90.4%, and 88.8% by coronary territory. CONCLUSIONS: DI-HS-MPI accurately detects functionally significant CAD as defined by using FFR.

SPECT myocardial ischemia in the absence of obstructive CAD: Contribution of the invasive assessment of microvascular dysfunction.

Coronary microvascular dysfunction has recently emerged as a major independent prognostic factor and can be invasively assessed by coronary flow reserve (CFR) and the index of microvascular resistance (IMR). The incremental prognostic value of myocardial ischemia from SPECT myocardial perfusion imaging (MPI) over clinical characteristics, cardiac risk factors, and stress test data for the prediction of hard cardiac events (myocardial infarction and cardiac death) has been well demonstrated over the last two decades regardless of the absence or presence of epicardial CAD. Recently developed semi-conductor, cardiac-dedicated cameras allow for decreased acquisition times and systematic procubitus and decubitus acquisitions thereby limiting the occurrence of false positives historically attributable to artefactual motion, attenuation, and digestive artifacts. It is therefore likely that pathophysiological causes rather than acquisition artifacts might underlie SPECT perfusion abnormalities. Here, we report four representative examples of patients presenting with ischemia in the setting of no obstructive CAD and normal fractional flow reserve together with elevated IMR and low CFR. The results indicate that ischemia from SPECT MPI could result from microvascular dysfunction in patients without obstructive CAD and should be considered as a prognostic factor for hard cardiac events.

Validation of HPLC and TLC analytical methods to determine radiochemical purity of 99mTc-cAbVCAM1-5, a new experimental radiotracer.

Cardiovascular diseases, including fatal myocardial infarctions from atheromatous plaques, are the primary global mortality cause. Detecting stenotic atheromatous plaques is possible through coronary angiography, but vulnerable plaques with eccentric remodeling are undetectable with current diagnostic methods. Addressing this challenge, our group developed a radiopharmaceutical drug targeting vascular cell adhesion molecule 1 (VCAM-1), radiolabeled with technetium-99m. Given the absence of a monograph in the European Pharmacopoeia, and in order to draft the investigational medicinal product documentation, analytical methods had to be validated by high performance liquid chromatography (HPLC) and thin layer chromatography (TLC) to determine the radiochemical purity (RCP) of 99mTc-cAbVCAM1-5. This study therefore presents the results of the validation of analytical methods obtained in this context. The method validation followed the European Association of Nuclear Medicine (EANM) recommendations adapted from ICH Q2(R1), ensuring conformity with specificity, accuracy, repeatability and intermediate precision, linearity, robustness, quantification limit (LoQ), and range criteria. Regarding the results of specificity, both HPLC and TLC methods demonstrated excellent separation of 99mTc-cAbVCAM1-5 from impurities 99mTcO4-. Accuracy results indicated recovery percentages within the range of 99.52-101.40% for the HPLC and 99.51-101.97% for TLC, ensuring reliable measurements for each concentration of 99mTcO4-. Precision of the methods was validated by assessing repeatability and intermediate precision. Linearity was determined over the usual concentrations range and the correlation coefficient was greater than 0.99 for both methods. The limit of quantification was measured by diluting the 99mTcO4- to obtain a signal-to-noise ratio of around 10:1. Under these conditions, we obtained an LOQ of 2.10 MBq/mL for HPLC and 2Mbq/mL for TLC. In conclusion, the analytical methods developed in this study comply with EANM recommendations. This therefore allows us to correctly assess the radiochemical purity of 99mTc-cAbVCAM1-5, a new radiotracer targeting inflammation in vulnerable plaques.

RECIP 1.0 Predicts Progression-Free Survival After [177Lu]Lu-PSMA Radiopharmaceutical Therapy in Patients with Metastatic Castration-Resistant Prostate Cancer.

Response Evaluation Criteria in Prostate-Specific Membrane Antigen Imaging (RECIP) 1.0 is an evidence-based framework to evaluate therapeutic efficacy in metastatic prostate cancer using prostate-specific membrane antigen (PSMA) PET/CT. This study aimed to evaluate the associations of interim PSMA PET/CT by RECIP 1.0 with short-term outcome after radiopharmaceutical treatment. Methods: This multicenter retrospective study included patients with metastatic castration-resistant prostate cancer who underwent [177Lu]Lu-PSMA radiopharmaceutical therapy at 3 academic centers and received PSMA PET/CT at baseline and at 12 wk. Pairs of PSMA PET/CT images were assessed by 5 readers for visual RECIP 1.0. The primary outcome was the association of RECIP with prostate-specific antigen progression-free survival (PSA-PFS) by Kaplan-Meier analysis. Results: In total, 124 of 287 screened patients met the inclusion criteria, with 0 (0%), 29 (23%), 54 (44%), and 41 (33%) of those 124 patients having complete response, partial response, stable disease, or progressive disease (PD) by visual RECIP 1.0, respectively. Patients with visual RECIP PD had a significantly shorter PSA-PFS than those with RECIP stable disease or with RECIP partial response (2.6 vs. 6.4 vs. 8.4 mo; P < 0.001). The median PSA-PFS among patients with RECIP PD versus those with non-RECIP PD was 2.6 versus 7.2 mo (hazard ratio, 13.0; 95% CI, 7.0-24.1; P < 0.001). Conclusion: PSMA PET/CT by RECIP 1.0 after 2 cycles of [177Lu]Lu-PSMA is prognostic for PSA-PFS. PSMA PET/CT by RECIP 1.0 may be used in earlier stages of prostate cancer to evaluate drug efficacy and to predict progression-free survival.

Phase 2 trial of PSMA PET CT versus planar bone scan and CT in prostate cancer patients progressing while on androgen deprivation therapy.

For prostate cancer patients who experience biochemical progression during androgen deprivation therapy (ADT), prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) has not been prospectively compared to planar bone scan plus CT. This was a single-arm, head-to-head, prospective phase II trial (NCT04928820) designed to enroll 102 men with prostate cancer who experienced biochemical progression (rising prostate-specific antigen [PSA] ≥ 1 ng/mL) during ADT. All patients received 68Ga-PSMA-11 PET/CT and 99mTc-MDP planar bone scans. Each scan was interpreted by three central independent readers. The primary endpoint was the per-patient bone metastasis detection rate of PSMA PET/CT versus planar bone scan and CT. Secondary endpoints compared the number of bone metastases detected per patient and the inter-reader agreement of each imaging modality. Twenty-two men were enrolled between July 2021 and June 2022. Due to slow accrual following approval of PSMA PET radiotracers in the U.S. and a lack of a statistical signal between the two imaging modalities on interim analysis, this trial was closed early on October 2022. Median PSA was 8.5 ng/mL (interquartile range: 1.6-77.6). There was 100% agreement between the two scans. Six patients (27%) had negative findings and 16 patients (73%) had positive findings on both scans. PSMA PET/CT and bone scan plus CT detected an equal number of bone lesions for 14 patients (64%), PSMA PET/CT detected more bone lesions for six patients (27%), and bone scan plus CT detected more bone lesions for two patients (9.1%) (p = 0.092). The inter-reader agreement rates of PSMA PET/CT and bone scan plus CT were 96% and 82%, respectively (p = 0.25). In men with biochemical progression during ADT, 68Ga-PSMA-11 PET/CT and 99mTc-MDP planar bone scan plus CT had identical bone metastasis detection rates. Bone scan plus CT can continue to serve as a cost-effective and readily accessible restaging modality in patients with biochemical progression. ClinicalTrials.gov NCT04928820. Registered 16/06/2021.

Differences and Common Ground in 177Lu-PSMA Radioligand Therapy Practice Patterns: International Survey of 95 Theranostic Centers.

177Lu-labeled prostate-specific membrane antigen (PSMA) radioligand therapy effectively treats metastatic castration-resistant prostate cancer. Patients requiring treatment, and consequently the number of theranostic centers, are expected to increase significantly after Food and Drug Administration and European Medicines Agency approval. This requires standardization or harmonization among theranostic centers. The aim of this study was to assess operational differences and similarities among 177Lu-PSMA treatment centers. Methods: A questionnaire comprising 62 items, designed by a core team of 5 physicians and externally reviewed by international experts, was developed. Study participants were asked to provide answers about their center, patient selection, radiopharmaceuticals, clinical assessment before and after 177Lu-PSMA treatments, laboratory values, treatment discontinuation, posttreatment imaging, and general information. An invitation e-mail to participate in the study was sent in June 2022. Duplicates were removed to allow for only one valid response per center. Results: Ninety-five of 211 (45%) contacted centers completed the questionnaire. Most participating centers were in Europe (51%), followed by America (22%) and Asia (22%). During the 12 mo before this study, a total of 5,906 patients received 177Lu-PSMA therapy at the 95 participating centers. Most of these patients were treated in Europe (2,840/5,906; 48%), followed by Asia (1,313/5,906; 22%) and Oceania (1,225/5,906; 21%). PSMA PET eligibility for 177Lu-PSMA was determined most frequently using 68Ga-PSMA-11 (77%). Additional pretherapy imaging included 18F-FDG PET/CT, CT, renal scintigraphy, and bone scintigraphy at 41 (49%), 27 (32%), 25 (30%), and 13 (15%), respectively, of the 84 centers for clinical standard of care, compassionate care, or local research protocols and 11 (26%), 25 (60%), 9 (21%), and 28 (67%), respectively, of the 42 centers for industry-sponsored trials. PSMA PET eligibility criteria included subjective qualitative assessment of PSMA positivity at 33% of centers, VISION criteria at 23%, and TheraP criteria at 13%. The mean standard injected activity per cycle was 7.3 GBq (range, 5.5-11.1 GBq). Sixty-two (65%) centers applied standardized response assessment criteria, and PSMA PET Progression Criteria were the most applied (37%). Conclusion: Results from this international survey revealed interinstitutional differences in several aspects of 177Lu-PSMA radionuclide therapy, including patient selection, administered activity, and the response assessment strategy. Standardization or harmonization of protocols and dedicated training are desirable in anticipation of increasing numbers of patients and theranostic centers.

Bacterial survival in radiopharmaceutical solutions: a critical impact on current practices.

BACKGROUND: The aim of this brief communication is to highlight the potential bacteriological risk linked to the processes control of radiopharmaceutical preparations made in a radiopharmacy laboratory. Survival rate of Pseudomonas aeruginosa (ATCC: 27853) or Staphylococcus aureus (ATCC: 25923) or Staphylococcus epidermidis (ATCC: 1228) in multidose technetium-99 m solution was studied. RESULTS: Depending on the nature and level of contamination by pathogenic bacteria, the lethal effect of radioactivity is not systematically observed. We found that P. aeruginosa was indeed affected by radioactivity. However, this was not the case for S. epidermidis, as the quantity of bacteria found in both solutions (radioactive and non-radioactive) was rapidly reduced, probably due to a lack of nutrients. Finally, the example of S. aureus is an intermediate case where we observed that high radioactivity affected the bacteria, as did the absence of nutrients in the reaction medium. The results were discussed in the light of current practices on the sterility test method, which recommends waiting for radioactivity to decay before carrying out the sterility test. CONCLUSION: In terms of patient safety, the results run counter to current practice and the latest EANM recommendation of 2021 that radiopharmaceutical preparations should be decayed before sterility testing.

TrisOxine abiotic siderophores for technetium complexation: radiolabeling and biodistribution studies.

BACKGROUND: Despite the development of positron emission tomography (PET), single photon emission computed tomography (SPECT) still accounts for around 80% of all examinations performed in nuclear medicine departments. The search for new radiotracers or chelating agents for Technetium-99m is therefore still ongoing. O-TRENSOX and O-TRENOX two synthetic siderophores would be good candidates for this purpose as they are hexadentate ligands based on the very versatile and efficient 8-hydroxyquinoline chelating subunit. First, the radiolabeling of O-TRENOX and O-TRENSOX with 99mTc was investigated. Different parameters such as the quantity of chelating agent, type of reducing agent, pH and temperature of the reaction mixture were adjusted in order to find the best radiolabeling conditions. Then an assessment of the partition coefficient by measuring the distribution of each radiosynthesized complex between octanol and phosphate-buffered saline was realized. The complex's charge was evaluated on three different celluloses (neutral, negatively charged P81 and positively charged DE81), and finally in vivo studies with biodistribution and SPECT imaging of [99mTc]Tc-O-TRENOX and [99mTc]Tc-O-TRENSOX were performed. RESULTS: The radiolabeling studies showed a rapid and efficient complexation of 99mTc with both chelating agents. Using tin pyrophosphate as the reducing agent and a minimum of 100 nmol of ligand, we obtained the [99mTc]Tc-O-TRENOX complex with a radiochemical purity of more than 98% and the [99mTc]Tc-O-TRENSOX complex with one above 97% at room temperature within 5 min. [99mTc]Tc-O-TRENOX complex was lipophilic and neutral, leading to a hepatobiliary elimination in mice. On the contrary, the [99mTc]Tc-O-TRENSOX complex was found to be hydrophilic and negatively charged. This was confirmed by a predominantly renal elimination in mice. CONCLUSIONS: These encouraging results allow us to consider the O-TRENOX/99mTc and O-TRENSOX/99mTc complexes as serious candidates for SPECT imaging chelators. This study should be continued by conjugating these tris-oxine ligands to peptides or antibodies and comparing them with the other bifunctional agents used with Tc.

Presurgical 68Ga-PSMA-11 Positron Emission Tomography for Biochemical Recurrence Risk Assessment: A Follow-up Analysis of a Multicenter Prospective Phase 3 Imaging Trial.

BACKGROUND: In the initial staging of patients with high-risk prostate cancer (PCa), prostate-specific membrane antigen positron emission tomography (PSMA-PET) has been established as a front-line imaging modality. The increasing number of PSMA-PET scans performed in the primary staging setting might be associated with decreases in biochemical recurrence (BCR)-free survival (BCR-FS). OBJECTIVE: To assess the added prognostic value of presurgical PSMA-PET for BCR-FS compared with the presurgical Cancer of the Prostate Risk Assessment (CAPRA) and postsurgical CAPRA-Surgery (CAPRA-S) scores in patients with intermediate- to high-risk PCa treated with radical prostatectomy (RP) and pelvic lymph node dissection. DESIGN, SETTING, AND PARTICIPANTS: This is a follow-up study of the surgical cohort evaluated in the multicenter prospective phase 3 imaging trial (n = 277; NCT03368547, NCT02611882, and NCT02919111). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Each 68Ga-PSMA-11-PET scan was read by three blinded independent readers. PSMA-PET prostate uptake (low vs high), PSMA-PET extraprostatic disease (N1/M1), and CAPRA and CAPRA-S scores were used to assess the risk of BCR. Patients were followed after RP by local investigators using electronic medical records. BCR was defined by a prostate-specific antigen (PSA) level increasing to ≥0.2 ng/ml after RP or initiation of PCa-specific secondary treatment (>6 mo after surgery). Univariate and multivariable Cox models, and c-statistic index were performed to assess the prognostic value of PSMA-PET and for a comparison with the CAPRA and CAPRA-S scores. RESULTS AND LIMITATIONS: From December 2015 to December 2019, 277 patients underwent surgery after PSMA-PET. Clinical follow-up was obtained in 240/277 (87%) patients. The median follow-up after surgery was 32.4 (interquartile range 23.3-42.9) mo. Of 240 BCR events, 91 (38%) were observed. PSMA-PET N1/M1 was found in 41/240 (17%) patients. PSMA-PET prostate uptake, PSMA-PET N1/M1, and CAPRA and CAPRA-S scores were significant univariate predictors of BCR. The addition of PSMA-PET N1/M1 status to the presurgical CAPRA score improved the risk assessment for BCR significantly in comparison with the presurgical CAPRA score alone (c-statistic 0.70 [0.64-0.75] vs 0.63 [0.57-0.69]; p < 0.001). The C-index of the postsurgical model utilizing the postsurgical CAPRA-S score alone was not significantly different from the presurgical model combining the presurgical CAPRA score and PSMA-PET N1/M1 status (p = 0.19). CONCLUSIONS: Presurgical PSMA-PET was a strong prognostic biomarker improving BCR-FS risk assessment. Its implementation in the presurgical risk assessment with the CAPRA score improved the performance and reduced the difference with the reference standard (postsurgical CAPRA-S score). PATIENT SUMMARY: The use prostate-specific membrane antigen positron emission tomography improved the assessment of biochemical recurrence risk in patients with intermediate- and high-risk prostate cancer who were treated with radical prostatectomy and pelvic lymph node dissection.