Extracellular fluid volume: A suitable indexation variable to assess impact of bariatric surgery on glomerular filtration rate in patients with chronic kidney disease.

BACKGROUND: Bariatric surgery (BS) might be a nephroprotective treatment in obese patients with chronic kidney disease (CKD), and the non-linear relation between body surface area (BSA) and extracellular fluid volume (ECFV) in obese people raises the question of the most relevant way to scale glomerular filtration rate (GFR) for assessing renal function changes after BS. METHODS: We screened 1774 BS candidates and analysed 10 consecutive participants with CKD stage 3. True GFR (mGFR), measured by the renal clearance of 51Cr-ethylenediaminetetraacetic acid (EDTA), was scaled either to BSA (mGFRBSA) or to ECFV measured by 51Cr-EDTA distribution volume (mGFRECFV) before and one year after BS. RESULTS: The 10 candidates for BS had a mean body mass index of 43.3 ± 3.6 kg/m2 and a mean GFR of 48 ± 8 mL/min/1.73 m2. Six participants had a sleeve gastrectomy and four had a Roux-en-Y gastric bypass. One year after BS, ECFV decreased (23.2 ± 6.2 to 17.9 ± 4.3 L, p = 0.001), absolute mGFR was not significantly modified (74 ± 23 versus 68 ±19 mL/min), mGFRBSA did not change significantly (53 ± 18 versus 56 ± 17 mL/min/1.73 m2) whereas mGFRECFV significantly increased (42 ± 13 versus 50 ± 14 mL/min/12.9 L, p = 0.037). The relation between mGFRECFV and mGFRBSA was different from the identity line before (p = 0.014) but not after BS (p = 0.09). CONCLUSION: There is a difference between mGFRBSA and mGFRECFV following BS and the latter might better reflect the adequacy between renal function and corpulence.

Mn(II) Complex of Lipophilic Group-Modified Ethylenediaminetetraacetic Acid (EDTA) as a New Hepatobiliary MRI Contrast Agent.

Liver-specific contrast agents (CAs) can improve the Magnetic resonance imaging (MRI) detection of focal and diffuse liver lesions by increasing the lesion-to-liver contrast. A novel Mn(II) complex, Mn-BnO-TyrEDTA, with a lipophilic group-modified ethylenediaminetetraacetic acid (EDTA) structure as a ligand to regulate its behavior in vivo, is superior to Gd-EOB-DTPA in terms of a liver-specific MRI contrast agent. An MRI study on mice demonstrated that Mn-BnO-TyrEDTA can be rapidly taken up by hepatocytes with a combination of hepatobiliary and renal clearance pathways. Bromosulfophthalein (BSP) inhibition imaging, biodistribution, and cellular uptake studies confirmed that the mechanism of hepatic targeting of Mn-BnO-TyrEDTA is the hepatic uptake of the amphiphilic anion contrast agent mediated by organic anion transporting polypeptides (OATPs) expressed by functional hepatocytes.

Preclinical Assessment Addressing Intravenous Administration of a [68Ga]Ga-PSMA-617 Microemulsion: Acute In Vivo Toxicity, Tolerability, PET Imaging, and Biodistribution.

It has been herein presented that a microemulsion, known to be an effective and safe drug delivery system following intravenous administration, can be loaded with traces of [68Ga]Ga-PSMA-617 without losing its properties or causing toxicity. Following tolerated IV injections the capability of the microemulsion in altering [68Ga]Ga-PSMA-617 distribution was presented at 120 min post injection based on its ex vivo biodistribution results.

Antihormone treatment differentially regulates PSA secretion, PSMA expression and 68Ga-PSMA uptake in LNCaP cells.

BACKGROUND: In recent years, a variety of innovative therapeutics for castration-resistant prostate cancer have been developed, including novel anti-androgenic drugs, such as abiraterone or VPC-13566. Therapeutic monitoring of these pharmaceuticals is performed either by measuring PSA levels in serum or by imaging. PET using PSMA ligands labeled with Fluor-18 or Gallium-68 is the most sensitive and specific imaging modality for detection of metastases in advanced prostate cancer. To date, it remains unclear how PSMA expression is modulated by anti-hormonal treatment and how it correlates with PSA secretion. METHODS: We analyzed modulation of PSMA-mRNA and protein expression, 68Ga-PSMA uptake and regulation of PSA secretion by abiraterone or VPC-13566 in LNCaP cells in vitro. RESULTS: We found that abiraterone and VPC-13566 upregulate PSMA protein and mRNA expression but block PSA secretion in LNCaP cells. Both anti-androgens also enhanced 68Ga-PSMA uptake normalized by the number of cells, whereas abiraterone and VPC-13566 reduced 68Ga-PSMA uptake in total LNCaP monolayers treated due to cell death. CONCLUSION: Our data indicate that PSA secretion and PSMA expression are differentially regulated upon anti-androgen treatment. This finding might be important for the interpretation of 68Ga-PSMA PET images in monitoring therapies with abiraterone and VPC-13566 in prostate cancer patients, but needs to be validated in vivo.

Biodistribution, dosimetry, and temporal signal-to-noise ratio analyses of normal and cancer uptake of [68Ga]Ga-P15-041, a gallium-68 labeled bisphosphonate, from first-in-human studies.

INTRODUCTION: [68Ga]Ga-P15-041 ([68Ga]Ga-HBED-CC-BP) is a novel bone-seeking PET radiotracer that can be generator-produced. We undertook a Phase 0/I clinical trial to assess its potential for imaging bone metastases in prostate cancer including assessment of radiotracer biodistribution and dosimetry. METHODS: Subjects with prostate cancer and known or suspected osseous metastatic disease were enrolled into one of two arms: dosimetry or dynamic. Dosimetry was performed with 6 whole body PET acquisitions and urine collection spanning 3 h; normal organ dosimetry was calculated using OLINDA/EXM. Dynamic imaging included a 60 min acquisition over a site of known or suspected disease followed by two whole body scans. Bootstrapping and subsampling of the acquired list-mode data were conducted to recommend image acquisition parameters for future clinical trials. RESULTS: Up to 233 MBq (6.3 mCi) of [68Ga]Ga-P15-041 was injected into 12 enrolled volunteers, 8 in dosimetry and 4 in dynamic cohorts. Radiotracer accumulated in known bone lesions and cleared rapidly from blood and soft tissue. The highest individual organ dose was 0.135 mSv/MBq in the urinary bladder wall. The average effective dose was 0.0173 ± 0.0036 mSv/MBq. An average injected activity of 166.5 MBq (4.5 mCi) resulted in absorbed dose estimates of 22.5 mSv to the urinary bladder wall, 8.2 mSv to the kidneys, and an effective dose of 2.9 mSv. Lesion signal to noise ratios on images generated from subsampled data were significantly higher for injected activities above 74 MBq (2 mCi) and were also significantly higher for imaging at 90 min than at 180 min post-injection. CONCLUSIONS: Dosimetry estimates are acceptable and [68Ga]Ga-P15-041 uptake characteristics in patients with confirmed bone metastases support its continued development. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE: Use of [68Ga]Ga-P15-041 would not require cyclotron infrastructure for manufacturing and distribution, allowing for improved patient access to a promising PET bone imaging agent.

Glomerular filtration rate: comparison of simultaneous plasma clearance of 99mTc-DTPA and 51Cr-EDTA revisited.

The issue of whether 99mTc-DTPA can replace 51Cr-EDTA for measurement of plasma clearance as a surrogate for glomerular filtration rate (GFR) is of great relevance to daily clinical practice. Prompted by the shortage of 51Cr-EDTA we conducted a head-to-head comparison in patients attending our department for GFR determination. The two tracers (3.7 MBq of 51Cr-EDTA and 8 MBq of 99mTc-DTPA) were administered intravenously immediately after each other, and the standard number of blood samples were drawn. Fifty-four patients were enrolled. In 51 of these, single-sample measurement was performed with the following results: GFREDTA was 84.6 ± 23.3 mL/min, GFRDTPA was 84.2 ± 24.7 mL/min. The mean difference was 0.4 ± 2.8 mL/min, p = 0.32, and results based on the two tracers were highly correlated (r = 0.995). GFRDTPA exceeded GFREDTA at high GFR values (difference < 0 at GFREDTA >91.4 mL/min) and vice versa (difference > 0 at GFREDTA < 91.4 mL/min). However, differences fell within few GFR units that most often will have no clinical consequence. We therefore conclude that 99mTc-DTPA can replace 51Cr-EDTA for single-sample determination of GFR in a clinical setting.

PET Imaging Quantifying 68Ga-PSMA-11 Uptake in Metastatic Colorectal Cancer.

At diagnosis, 22% of colorectal cancer (CRC) patients have metastases, and 50% later develop metastasis. Peptide receptor radionuclide therapy (PRRT), such as 177Lu-PSMA-617, is used to treat metastatic prostate cancer. 177Lu-PSMA-617 targets prostate-specific membrane antigen (PSMA), a cell-surface protein enriched in prostate cancer and the neovasculature of other solid tumors, including CRC. We performed 68Ga-PSMA-11 PET/CT imaging of 10 patients with metastatic CRC to assess metastasis avidity. Eight patients had lesions lacking avidity, and 2 had solitary metastases exhibiting very low avidity. Despite expression of PSMA in CRC neovasculature, none of the patients exhibited tumor avidity sufficient to be considered for 177Lu-PSMA-617 PRRT.

68Ga-PSMA-Guided Bone Biopsies for Molecular Diagnostics in Patients with Metastatic Prostate Cancer.

For individual treatment decisions in patients with metastatic prostate cancer (mPC), molecular diagnostics are increasingly used. Bone metastases are frequently the only source for obtaining metastatic tumor tissue. However, the success rate of CT-guided bone biopsies for molecular analyses in mPC patients is approximately only 40%. PET using 68Ga prostate-specific membrane antigen (68Ga-PSMA) is a promising tool to improve the harvest rate of bone biopsies for molecular analyses. The aim of this study was to determine the success rate of 68Ga-PSMA-guided bone biopsies for molecular diagnostics in mPC patients. Methods: Within a prospective multicenter whole-genome sequencing trial (NCT01855477), 69 mPC patients underwent 68Ga-PSMA PET/CT before bone biopsy. The primary endpoint was the success rate (tumor percentage ≥ 30%) of 68Ga-PSMA-guided bone biopsies. At biopsy sites, 68Ga-PSMA uptake was quantified using rigid-body image registration of 68Ga-PSMA PET/CT and interventional CT. Actionable somatic alterations were identified. Results: The success rate of 68Ga-PSMA-guided biopsies for molecular analyses was 70%. At biopsy sites categorized as positive, inconclusive, or negative for 68Ga-PSMA uptake, 70%, 64%, and 36% of biopsies were tumor-positive (≥30%), respectively (P = 0.0610). In tumor-positive biopsies, 68Ga-PSMA uptake was significantly higher (P = 0.008), whereas radiodensity was significantly lower (P = 0.006). With an area under the curve of 0.84 and 0.70, both 68Ga-PSMA uptake (SUVmax) and radiodensity (mean Hounsfield units) were strong predictors for a positive biopsy. Actionable somatic alterations were detected in 73% of the sequenced biopsies. Conclusion: In patients with mPC, 68Ga-PSMA PET/CT improves the success rate of CT-guided bone biopsies for molecular analyses, thereby identifying actionable somatic alterations in more patients. Therefore, 68Ga-PSMA PET/CT may be considered for guidance of bone biopsies in both clinical practice and clinical trials.

EDTA-Modified 17ß-Estradiol-Laden Upconversion Nanocomposite for Bone-Targeted Hormone Replacement Therapy for Osteoporosis.

Hormone therapy (HT) is one of the most effective treatments for osteoporosis. However, the nonselective accumulation of hormone in organs such as breast, heart and uterus other than bones causes serious side effects, which impedes the application of HT. Hence, it is critically important to develop a HT strategy with reduced non-specific enrichment of hormone drugs in non-target tissues and enhanced bone-targeting ability. Methods: Herein, a 17ß-estradiol (E2)-laden mesoporous silica-coated upconversion nanoparticle with a surface modification of ethylenediaminetetraacetic acid (EDTA) (NaLuF4:Yb,Tm@NaLuF4@mSiO2-EDTA-E2, E2-csUCNP@MSN-EDTA) is developed for bone-targeted osteoporosis hormone therapy. EDTA was attached onto the surface of E2 upconversion nanocomposite to enhance its affinity and efficiency targeting bone tissue and cells to optimize hormone replacement therapy for osteoporosis. We characterized the size, cytotoxicity, loading and release efficiency, in situ and ex vivo imaging. Further, in vitro and in vivo osteogenic ability was tested using preosteoblast and ovariectomy mouse model of osteoporosis. Results: The upconversion core of E2-csUCNP@MSN-EDTA nanoparticle serves as an excellent imaging agent for tracking the loaded hormone drug in vivo. The mesoporous silica layer has a high loading efficiency for E2 and provides a relatively long-lasting drug release within 50 h. EDTA anchored on the silica layer endows the nanocomposite with a bone targeting property. The nanocomposite effectively reverses estrogen deficiency-induced osteoporosis and reduces the damage of hormone to the uterus. The bone mineral density in the nanocomposite treatment group is nearly twice that of the ovariectomized (OVX) group. Compared with the E2 group, the uterine weight and luminal epithelial height were significantly lower in the nanocomposite treatment group. Conclusion: This work demonstrated that E2-csUCNP@MSN-EDTA alleviates the side effect of hormone therapy while maintaining its therapeutic efficacy, which has great potential for developing the next generation of methods for osteoporosis treatment.

68Ga-PSMA-HBED-CC PET/CT imaging for adenoid cystic carcinoma and salivary duct carcinoma: a phase 2 imaging study.

Rationale: Treatment options for recurrent and/or metastatic (R/M) adenoid cystic carcinoma (ACC) and salivary duct carcinoma (SDC), major subtypes of salivary gland cancer, are limited. Both tumors often show overexpression of prostate-specific membrane antigen (PSMA). In prostate cancer, PSMA-ligands labeled with 68Ga or 177Lu are used for imaging and therapy, respectively. Primary aim of this study in R/M ACC and SDC patients was to systematically investigate 68Ga-PSMA-uptake by PET/CT imaging to determine if PSMA radionuclide therapy could be a treatment option. Methods: In a prospective phase II study, PET/CT imaging was performed 1 h post injection of 68Ga-PSMA-HBED-CC in 15 ACC patients and 10 SDC patients. Maximum standardized uptake values (SUV) were determined in tumor lesions. Immunohistochemical PSMA expression was scored in primary tumors and metastatic tissue. Standard imaging (MRI or CT) was performed for comparison. Results: In ACC patients, SUVmax ranged from 1.1 to 30.2 with a tumor/liver-ratio >1 in 13 out of 14 evaluable patients (93%). In SDC patients, SUVmax ranged from 0.3 to 25.9 with a tumor/liver-ratio >1 in 4 out of 10 patients (40%). We found a large intra-patient inter-metastatic variation in uptake of 68Ga-PSMA, and immunohistochemistry did not predict ligand uptake in ACC and SDC. Finally, PSMA-PET detected additional bone metastases compared to CT in 2 ACC patients with unexplained pain. Conclusion: In 93% of ACC patients and 40% of SDC patients we detected relevant PSMA-ligand uptake, which warrants to study PSMA radionuclide therapy in these patients. Additionally, our data provide arguments for patient selection and treatment timing. Finally, PSMA-PET imaging has added diagnostic value compared to CT in selected patients.

Postoperative Renal Function in Patients Undergoing Unilateral Nephrectomy: Development of a Prediction Model Using Preoperative Risk Factors and 51Cr-EDTA Clearance.

Objectives: To analyze the preoperative variables associated to the postoperative glomerular filtration rate (GFR) outcomes after nephrectomy for benign and malignant conditions, measured by the reference isotopic technique 51Cr-ethylene diamine tetra-acetic (51Cr-EDTA) and to create a model to predict the short-term postoperative GFR. Secondary aim was to evaluate which of the common equations for GFR estimation (Cockcroft-Gault, Modification of Diet in Renal Disease [MDRD] or Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI]) has the best correlation with the 51Cr-EDTA. Methods: Patients undergoing unilateral nephrectomy from 2014 to 2018 were selected. Pre- and postoperative variables were prospectively collected. Univariate and multivariate analyses were done to identify independent risk factors associated with renal function outcomes and to create a model to predict the postoperative GFR. Correlation analyses were performed to evaluate the performance of various serum creatinine-based equations for GFR estimation compared with 51Cr-EDTA. Results: In total, 107 patients were evaluated. After univariate and multivariate analyses, older age (p = 0.008), higher split function of the operated kidney on dimercaptosuccinic acid (DMSA) scintigraphy (p < 0.001), and lower preoperative 51Cr-EDTA (p < 0.001) were independent risk factors for higher GFR decline. Correlation analyses showed that GFR estimated by CKD-EPI equation had the best concordance to GFR measured by 51Cr-EDTA. Conclusions: Based on our findings age, DMSA and lower preoperative 51Cr-EDTA are predictors of postoperative renal function after unilateral nephrectomy. For the assessment of estimated GFR, CKD-EPI equation appears to have the best concordance with 51Cr-EDTA.

Prostate-Specific Membrane Antigen Expression in Primary Juvenile Nasal Angiofibroma-A Pilot Study.

PURPOSE: Prostate-specific membrane antigen (PSMA) is highly expressed in prostate cancer cells and is exploited for imaging and treatment of patients with prostate cancer. Prostate-specific membrane antigen expression is also demonstrated in the tumor-associated neovasculature endothelium. Juvenile nasal angiofibroma (JNA), being a similar highly vascular tumor, may also demonstrate significant PSMA expression, which may be utilized for its imaging and treatment. METHODS: In this prospective study, 25 clinicoradiologically diagnosed primary JNA patients underwent PSMA PET/CT scan. The scan was performed after 45 to 60 minutes of intravenous injection of 2 to 3 mCi (74-111 MBq) of Ga-PSMA-HBED-CC on a dedicated PET/CT scanner. Low-dose CT scan was acquired from vertex to sternoclavicular joint (100 mA, 20 kVp, 3-mm slice thickness, 0.8 pitch). Images were reconstructed with iterative reconstruction technique (4 iterations, 24 subsets). The objective was to assess the intensity and pattern of PSMA uptake in primary JNA patients. RESULTS: All cases (n = 25) of primary JNA showed PSMA expression in the tumor (100%). The median PSMA SUVmax ratio of tumor to background was 4.57 (range, 2.08-7.27). Intracranial extension in 14 of 25 patients was prominently visualized because of absence of background uptake in the brain. Advanced stage tumors demonstrated greater uptake than early tumors (P = 0.011). A statistically nonsignificant trend was noted for decreasing uptake with increasing age after normalizing for stage (Spearman correlation coefficient r = -0.08). CONCLUSIONS: Assessment of PSMA expression in JNA by PSMA PET/CT opens up a new window of opportunity with respect to its radiological staging, vascularity assessment, and molecular characterization. A potential role in identification of the difficult residual-recurrent disease is anticipated and perhaps also in radioligand therapy for residual/recurrent JNA.Clinical Trials Registry of India (CTRI/2018/08/015479).

[68Ga]Ga-P16-093 as a PSMA-Targeted PET Radiopharmaceutical for Detection of Cancer: Initial Evaluation and Comparison with [68Ga]Ga-PSMA-11 in Prostate Cancer Patients Presenting with Biochemical Recurrence.

PURPOSE: This study was undertaken to evaluate radiation dosimetry for the prostate-specific membrane antigen targeted [68Ga]Ga-P16-093 radiopharmaceutical, and to initially assess agent performance in positron emission tomography (PET) detection of the site of disease in prostate cancer patients presenting with biochemical recurrence. PROCEDURES: Under IND 133,222 and an IRB-approved research protocol, we evaluated the biodistribution and pharmacokinetics of [68Ga]Ga-P16-093 with serial PET imaging following intravenous administration to ten prostate cancer patients with biochemical recurrence. The recruited subjects were all patients in whom a recent [68Ga]Ga-PSMA-11 PET/X-ray computed tomography (CT) exam had been independently performed under IND 131,806 to assist in decision-making with regard to their clinical care. Voided urine was collected from each subject at ~ 60 min and ~ 140 min post-[68Ga]Ga-P16-093 injection and assayed for Ga-68 content. Following image segmentation to extract tissue time-activity curves and corresponding cumulated activity values, radiation dosimetry estimates were calculated using IDAC Dose 2.1. The prior [68Ga]Ga-PSMA-11 PET/CT exam (whole-body PET imaging at 60 min post-injection, performed with contrast-enhanced diagnostic CT) served as a reference scan for comparison to the [68Ga]Ga-P16-093 findings. RESULTS: [68Ga]Ga-P16-093 PET images at 60 min post-injection provided diagnostic information that appeared equivalent to the subject's prior [68Ga]Ga-PSMA-11 scan. With both radiopharmaceuticals, sites of tumor recurrence were found in eight of the ten patients, identifying 16 lesions. The site of recurrence was not detected with either agent for the other two subjects. Bladder activity was consistently lower with [68Ga]Ga-P16-093 than [68Ga]Ga-PSMA-11. The kidneys, spleen, salivary glands, and liver receive the highest radiation exposure from [68Ga]Ga-P16-093, with estimated doses of 1.7 × 10-1, 6.7 × 10-2, 6.5 × 10-2, and 5.6 × 10-2 mGy/MBq, respectively. The corresponding effective dose from [68Ga]Ga-P16-093 is 2.3 × 10-2 mSv/MBq. CONCLUSIONS: [68Ga]Ga-P16-093 provided diagnostic information that appeared equivalent to [68Ga]Ga-PSMA-11 in this limited series of ten prostate cancer patients presenting with biochemical recurrence, with the kidneys found to be the critical organ. Diminished tracer appearance in the urine represents a potential advantage of [68Ga]Ga-P16-093 over [68Ga]Ga-PSMA-11 for detection of lesions in the pelvis.

Whole-Body Integrated [68Ga]PSMA-11-PET/MR Imaging in Patients with Recurrent Prostate Cancer: Comparison with Whole-Body PET/CT as the Standard of Reference.

PURPOSE: The aim of this study was to evaluate the detection rate of [68Ga]prostate-specific membrane antigen ([68Ga]PSMA-11) positron emission tomography (PET)/magnetic resonance imaging (MRI) and to compare it with [68Ga]PSMA-11 PET/X-ray computed tomography (CT) in patients with recurrent prostate cancer (PC) after radical prostatectomy. PROCEDURES: A total of 93 patients with biochemically recurrent prostate cancer underwent [68Ga]PSMA-11 PET/CT and subsequently a whole-body integrated PET/MRI examination. Board certified nuclear medicine physicians and radiologists evaluated PET/CT and PET/MRI datasets regarding identification of tumor lesions ((i) lymph nodes, (ii) bone lesions, (iii) local recurrence, and (iv) parenchymal lesions) based on maximum [68Ga]PSMA-11 uptake as well as morphological changes. Quality of PET images for both PET/CT and PET/MRI were rated using a 5-point scoring system by evaluating lesion homogeneity, contrast, contour, and delineation. Wilcoxon signed-rank tests were used to determine statistical differences. RESULTS: PC relapse was detected in 62/93 patients. PET/MRI detected 148 out of 150 lesions described in PET/CT. In addition, PET/MRI detected 11 lesions not detected in PET/CT (5 lymph nodes, 6 local recurrences). The exact McNemar statistical test (one-sided) showed significant difference between PET/CT and PET/MRI for diagnosis of local recurrence (p value = 0.031). Diagnostic confidence for (iii) was higher in PET/MRI compared with PET/CT (PET/CT = 1.1; PET/MRI = 4.9). Diagnostic confidence for (i) (PET/CT = 4.9; PET/MRI = 4.6), (ii) (PET/CT = 4.9; PET/MRI = 4.6), and (iv) (PET/CT = 4.6; PET/MRI = 4.8) was equivalent between PET/MRI and PET/CT. CONCLUSIONS: Integrated [68Ga]PSMA-11 PET/MRI provides a similarly high diagnostic performance for localization of recurrent PC as PET/CT. For the detection of local recurrences [68Ga]PSMA-11 PET/MRI is superior compared with [68Ga]PSMA-11 PET/CT.

[68Ga]Ga-HBED-CC-DiAsp: A new renal function imaging agent.

INTRODUCTION: [68Ga]Ga-EDTA ([68Ga]Ga-ethylenediaminetetraacetic acid) was previously reported as a renal imaging agent for measuring GFR (glomerular filtration rate). In an effort to provide new agents with better in vivo characteristics for renal imaging, [68Ga]Ga-HBED-CC-DiAsp (Di-Aspartic acid derivative of N,N'-bis [2-hydroxy-5-(carboxyethyl)benzyl]-ethylenediamine-N,N'-diacetic acid) was prepared and tested. METHOD: HBED-CC-DiAsp was synthesized and labeled with [68Ga]GaCl4- at room temperature. Plasma protein and red blood cells (RBC) binding were also evaluated. Biodistribution and dynamic PET imaging studies were performed in mice and rats, respectively. RESULTS: [68Ga]Ga-HBED-CC-DiAsp was radiolabeled at room temperature by a one-step kit formulation in high purity without any purification (radiochemical purity >98%). Previous reports suggested that Ga-HBED-CC exhibited a higher stability constant and rapid chelating formation rate than that of Ga-EDTA (logKGaL = 38.5 vs 22.1, respectively). In vitro stability studies indicated that it was stable up to 120 min. The log DOW value, partition coefficient between n-octanol and water, was found to be -2.52 ± 0.08. Plasma protein and RBC binding was similar to that observed for [68Ga]Ga-EDTA. Biodistribution and dynamic PET/CT imaging studies in rats revealed a rapid clearance primarily through the renal-urinary pathway. The PET-derived [68Ga]Ga-HBED-CC-DiAsp renograms in rats showed an average time-to-peak of 3.6 ± 0.7 min which was similar to that observed for [68Ga]Ga-EDTA (3.1 ± 0.5 min). The time-to-half-maximal activity was also comparable to that of [68Ga]Ga-EDTA (8.8 vs 8.2 min, respectively). Pretreatment of probenecid, a renal tubular excretion inhibitor, showed no significant effect on renal excretion. CONCLUSIONS: [68Ga]Ga-HBED-CC-DiAsp could be prepared quickly at room temperature in high yield and purity. Results of in vitro studies and in vivo biodistribution in mice and rats suggested that [68Ga]Ga-HBED-CC-DiAsp might be useful as a PET imaging agent for measurement of GFR.

Contribution of 5th minute and 2nd hour images to standard imaging in (68Ga)PSMA 11 PET/CT.

OBJECTIVE: To investigate the superiority or contribution of 5th minute pelvic and 2nd hour whole body Gallium68-prostate-specific membrane antigen-HBED-CC [(68Ga)PSMA 11] Positron Emission Tomography/Computed Tomography (PET/CT) images to 1st hour imaging in patients with prostate cancer (PCa). MATERIALS AND METHODS: A total of 63 patients diagnosed with PCa who underwent (68Ga)PSMA 11 PET/CT between April 2019 and June 2019 and who had 5th minute and 1st and 2nd hour images were included in the study. Early (5th minute) pelvic region and 1st and 2nd hour full body images were obtained from all patients. The regions of interest (ROI) were drawn from the background tissues and the physiological uptake sites in a way to include the same lesions from primary and metastatic lesions in all three imagings, and SUVmax values, and tumor-background ratio (TBR) were calculated. RESULTS: The mean age of the patients was 69.81 ± 8.78 (min/max: 51/91) years. In the 5th minute images, prostate gland and bed were easier to evaluate, because of low bladder activity. However, lymph node evaluation was more difficult due to high vascular activity. In the prostate gland, lymph nodes and bone metastases, both SUVmax values and TBR rates increased with time from the 5th minute (p < 0.001). At the 2nd hour, some lesions became more visible, while decreased activity was observed in some lesions. However, none of the patients required a change in the stage or treatment. CONCLUSION: In conclusion, the 5th minute pelvic images in (68Ga)PSMA 11 PET/CT were helpful in visual evaluation of the prostate gland and bed, while 2nd hour images showed high SUVmax and TBR rates in malignant lesions. As the SUVmax values of benign lesions were found to be lower in the 2nd hour, when compared to the 1st hour, it was thought that the 2nd hour imaging could be used in the additional imaging for suspicious lesions without the need for very long waiting times.

The "question-mark" MR anatomy of the cervico-thoracic ganglia complex: can it help to avoid mistaking it for a malignant lesion on 68Ga-PSMA-11 PET/MR?

Background Detectable uptake of 68Ga-PSMA-ligands in sympathetic ganglia may potentially lead to mistaking them for malignant lesions. Our aim was to investigate the anatomy of cervico-thoracic-ganglia-complex (CTG-C) in the MR part of multimodal 68Ga-PSMA-11 PET/MR imaging, in view of PET factors hindering its proper identification. Patients and methods In 106 patients, 212 sites of the CTG-C were retrospectively reviewed to assess the radiotracer uptake (SUVmax), size, shape, position, symmetry of location and visual uptake intensity. Asymmetry of PSMA-ligand uptake and increased uptake were regarded as risk factors of malignancy. Results In 66.0% left (L) and 53.8% right (R) CTG-C we noticed configurations, resembling the shape of an exclamation-mark, a question-mark, or its part (called "typical"). Tumor-like CTG-C shapes (oval, binodular or longitudinal) were detected in 28.3% L-CTG-C and in 40.6% R-CTG-C. When visual assessment of PET suggested malignancy, the recognition of "typical" shape of underlying CTG-C on MR generated a rise in the accuracy of their proper identification (from 34.4% to 75%, χ2(1) = 70.4; p < 0.001). Recognizing the shape of the CTG-C as "typical" in MR allowed us to classify as "not-suspicious" 61.9% of all CTG-C which were treated as "suspicious" after sole PET assessment. Conclusions The characteristic shape of cervico-thoracic-ganglia-complex (resembling a question-mark, or its part) helps in proper recognition of CTG-C on multimodal whole-body 68Ga-PSMA-ligand PET/MR imaging, when detectable uptake might lead to considering pathology.

Manganese-Enhanced MRI of the Brain in Healthy Volunteers.

BACKGROUND AND PURPOSE: The manganese ion is used as an intracellular MR imaging contrast agent to study neuronal function in animal models, but it remains unclear whether manganese-enhanced MR imaging can be similarly useful in humans. Using mangafodipir (Teslascan, a chelated manganese-based contrast agent that is FDA-approved), we evaluated the dynamics of manganese enhancement of the brain and glandular structures in the rostral head and neck in healthy volunteers. MATERIALS AND METHODS: We administered mangafodipir intravenously at a rate of 1 mL/minute for a total dose of 5 µmol/kg body weight. Nine healthy adult volunteers (6 men/3 women; median age, 43 years) completed baseline history and physical examination, 3T MR imaging, and blood work. MR imaging also followed mangafodipir administration at various time points from immediate to 7 days, with delayed scans at 1-3 months. RESULTS: The choroid plexus and anterior pituitary gland enhanced within 10 minutes of infusion, with enhancement persisting up to 7 and 30 days, respectively. Exocrine (parotid, submandibular, sublingual, and lacrimal) glands also enhanced avidly as early as 1 hour postadministration, generally resolving by 1 month; 3 volunteers had residual exocrine gland enhancement, which resolved by 2 months in 1 and by 3 months in the other 2. Mangafodipir did not affect clinical parameters, laboratory values, or T1-weighted signal in the basal ganglia. CONCLUSIONS: Manganese ions released from mangafodipir successfully enable noninvasive visualization of intra- and extracranial structures that lie outside the blood-brain barrier without adverse clinical effects, setting the stage for future neuroradiologic investigation in disease.

Synthesis and Initial Biological Evaluation of Boron-Containing Prostate-Specific Membrane Antigen Ligands for Treatment of Prostate Cancer Using Boron Neutron Capture Therapy.

Boron neutron capture therapy (BNCT) is a therapeutic modality which has been used for the treatment of cancers, including brain and head and neck tumors. For effective treatment via BNCT, efficient and selective delivery of a high boron dose to cancer cells is needed. Prostate-specific membrane antigen (PSMA) is a target for prostate cancer imaging and drug delivery. In this study, we conjugated boronic acid or carborane functional groups to a well-established PSMA inhibitor scaffold to deliver boron to prostate cancer cells and prostate tumor xenograft models. Eight boron-containing PSMA inhibitors were synthesized. All of these compounds showed a strong binding affinity to PSMA in a competition radioligand binding assay (IC50 from 555.7 to 20.3 nM). Three selected compounds 1a, 1d, and 1f were administered to mice, and their in vivo blocking of 68Ga-PSMA-11 uptake was demonstrated through a positron emission tomography (PET) imaging and biodistribution experiment. Biodistribution analysis demonstrated boron uptake of 4-7 µg/g in 22Rv1 prostate xenograft tumors and similar tumor/muscle ratios compared to the ratio for the most commonly used BNCT compound, 4-borono-l-phenylalanine (BPA). Taken together, these data suggest a potential role for PSMA targeted BNCT agents in prostate cancer therapy following suitable optimization.

Drug-eluting fully covered self-expanding metal stent for dissolution of bile duct stones in vitro.

BACKGROUND: The treatment of difficult common bile duct stones (CBDS) remains a big challenge around the world. Biliary stenting is a widely accepted rescue method in patients with failed stone extraction under endoscopic retrograde cholangiopancreatography. Fully covered self-expanding metal stent (FCSEMS) has gained increasing attention in the management of difficult CBDS. AIM: To manufacture a drug-eluting FCSEMS, which can achieve controlled release of stone-dissolving agents and speed up the dissolution of CBDS. METHODS: Customized covered nitinol stents were adopted. Sodium cholate (SC) and disodium ethylene diamine tetraacetic acid (EDTA disodium, EDTA for short) were used as stone-dissolving agents. Three different types of drug-eluting stents were manufactured by dip coating (Stent I), coaxial electrospinning (Stent II), and dip coating combined with electrospinning (Stent III), respectively. The drug-release behavior and stone-dissolving efficacy of these stents were evaluated in vitro to sort out the best manufacturing method. And the selected stone-dissolving stents were further put into porcine CBD to evaluate their biosecurity. RESULTS: Stent I and Stent II had obvious burst release of drugs in the first 5 d while Stent III presented controlled and sustainable drug release for 30 d. In still buffer, the final stone mass-loss rate of each group was 5.19% ± 0.69% for naked FCSEMS, 20.37% ± 2.13% for Stent I, 24.57% ± 1.45% for Stent II, and 33.72% ± 0.67% for Stent III. In flowing bile, the final stone mass-loss rate of each group was 5.87% ± 0.25% for naked FCSEMS, 6.36% ± 0.48% for Stent I, 6.38% ± 0.37% for Stent II, and 8.15% ± 0.27% for Stent III. Stent III caused the most stone mass-loss no matter in still buffer or in flowing bile, which was significantly higher than those of other groups (P < 0.05). In vivo, Stent III made no difference from naked FCSEMS in serological analysis (P > 0.05) and histopathological examination (P > 0.05). CONCLUSION: The novel SC and EDTA-eluting FCSEMS is efficient in diminishing CBDS in vitro. When conventional endoscopic techniques fail to remove difficult CBDS, SC and EDTA-eluting FCSEMS implantation may be considered a promising alternative.