Highlights lecture EANM 2016: "Embracing molecular imaging and multi-modal imaging: a smart move for nuclear medicine towards personalized medicine"

PET tracer development for imaging α-synucleinopathies

Abnormal α-synuclein aggregation is a key neuropathological hallmark of α-synucleinopathies, such as Parkinson's disease (PD), multiple system atrophy (MSA), and several other neurological disorders, and closely contributes to pathogenesis. The primary characteristics of α-synucleinopathies are selective targeted neurodegeneration and the accumulation of Lewy pathologies. Specifically, α-synuclein positron emission tomography (PET) radiotracers target the fibrillar forms of the protein, thus enhancing early diagnosis and the evaluation of treatment effectiveness for various α-synucleinopathies. Therefore, in vivo detection of α-synuclein aggregates using targeted radiolabeled probes would aid in drug development, early diagnosis, and ongoing disease monitoring. As such, no promising α-synuclein biomarkers suitable for clinical applications have been reported. PET is a valuable non-invasive technique for imaging drug distribution in tissues and receptor occupancy at target sites in living animals and humans. Advances in PET biomarkers have significantly enhanced our understanding of the mechanisms underlying PD. This review summarizes recent ongoing efforts in the development of selective PET tracers for α-synuclein and discusses future perspectives.

Cancer Targeting Radiopeptidomimetics in Molecular Nuclear Medicine

Peptides are highly receptor-affine molecules exhibiting suitable pharmacokinetics. Additionally, low-cost production, simple protocols allowing easy modifications, and tolerance toward harsh reaction conditions make peptides ideal ligands for preparation of radiopharmaceuticals for cancer detection and treatment. However, natural peptides being substrates for enzymes are susceptible to proteolysis, which limits the in vivo lifetime and the target uptake. Therefore, the majority of peptides are not able to progress beyond preclinical research. Advancement of peptides for clinical analysis needs modification to instill improved features. Continuous increase and further expected rise in cancer cases in the next decade require development of more disease-directed and promising radiopharmaceuticals. Redesigned peptide, mimicking the original peptide with similar or improved affinity and high metabolic stability, shall have significant edge. This review outlines the design of peptidomimetics by incorporation of D-amino acids (inverso); reversal of D-amino acid sequence (retro-inverso), and reversal of L-amino acid sequence (retro). Clinically successful radiopeptidomimetics prepared using the three approaches have been elaborated to elucidate the important role of peptidomimetics in cancer management.

A review of the current research on in vivo and in vitro detection for alpha-synuclein: a biomarker of Parkinson's disease

Parkinson's disease is a health-threatening neurodegenerative disease of the elderly with clinical manifestations of motor and non-motor deficits such as tremor palsy and loss of smell. Alpha-synuclein (α-Syn) is the pathological basis of PD, it can abnormally aggregate into insoluble forms such as oligomers, fibrils, and plaques, causing degeneration of nigrostriatal dopaminergic neurons in the substantia nigra in the patient's brain and the formation of Lewy bodies (LBs) and Lewy neuritis (LN) inclusions. As a result, achieving α-Syn aggregate detection in the early stages of PD can effectively stop or delay the progression of the disease. In this paper, we provide a brief overview and analysis of the molecular structures and α-Syn in vivo and in vitro detection methods, such as mass spectrometry, antigen-antibody recognition, electrochemical sensors, and imaging techniques, intending to provide more technological support for detecting α-Syn early in the disease and intervening in the progression of Parkinson's disease.

The Role of Molecular Imaging in Personalized Medicine

The concept of personalized medicine refers to the tailoring of medical treatment to each patient's unique characteristics. Scientific advancements have led to a better understanding of how a person's unique molecular and genetic profile makes them susceptible to certain diseases. It provides individualized medical treatments that will be safe and effective for each patient. Molecular imaging modalities play an essential role in this aspect. They are used widely in screening, detection and diagnosis, treatment, assessing disease heterogeneity and progression planning, molecular characteristics, and long-term follow-up. In contrast to conventional imaging approaches, molecular imaging techniques approach images as the knowledge that can be processed, allowing for the collection of relevant knowledge in addition to the evaluation of enormous patient groups. This review presents the fundamental role of molecular imaging modalities in personalized medicine.

Recent Developments in Positron Emission Tomography Tracers for Proteinopathies Imaging in Dementia

An early detection and intervention for dementia represent tremendous unmet clinical needs and priorities in society. A shared feature of neurodegenerative diseases causing dementia is the abnormal accumulation and spreading of pathological protein aggregates, which affect the selective vulnerable circuit in a disease-specific pattern. The advancement in positron emission tomography (PET) biomarkers has accelerated the understanding of the disease mechanism and development of therapeutics for Alzheimer's disease and Parkinson's disease. The clinical utility of amyloid-β PET and the clinical validity of tau PET as diagnostic biomarker for Alzheimer's disease continuum have been demonstrated. The inclusion of biomarkers in the diagnostic criteria has introduced a paradigm shift that facilitated the early and differential disease diagnosis and impacted on the clinical management. Application of disease-modifying therapy likely requires screening of patients with molecular evidence of pathological accumulation and monitoring of treatment effect assisted with biomarkers. There is currently still a gap in specific 4-repeat tau imaging probes for 4-repeat tauopathies and α-synuclein imaging probes for Parkinson's disease and dementia with Lewy body. In this review, we focused on recent development in molecular imaging biomarkers for assisting the early diagnosis of proteinopathies (i.e., amyloid-β, tau, and α-synuclein) in dementia and discussed future perspectives.

Chemical and Physical Characterisation of Human Serum Albumin Nanocolloids: Kinetics, Strength and Specificity of Bonds with 99mTc and 68Ga

Nanoparticles of Human Serum Albumin (NC) labelled with ^99mTc are widely used in Nuclear Medicine and represent the gold-standard for the intraoperative detection of the sentinel lymph node in many kinds of cancer, mainly breast cancer and melanoma. A significant amount of radionuclides can be incorporated into the HSA particle, due to the multiple binding sites, and HSA-based nanocolloid catabolism is a fast and easy process that results in innocuous degradation products. NCs labelled with different isotopes represent an interesting radiopharmaceutical for extending diagnostic accuracy and surgical outcome, but the knowledge of the chemical bond between NCs and isotopes has not been fully elucidated, including information on its strength and specificity. The aim of this study is to investigate and compare the physicochemical characteristics of the bond between NCs and ^99mTc and ⁶⁸Ga isotopes. Commercial kits of HSA-based nanocolloid particles (NanoAlbumon^®) were used. For this purpose, we have primarily studied the kinetic orders of NC radiolabelling. Langmuir isotherms and pH effect on radiolabelling were tested and the stability of the radiometal complex was verified through competition reactions carried out in presence of different ligands. The future goal of our research is the development of inexpensive and instant kits, easily labelled with a wide spectrum of diagnostic and therapeutic isotopes, thus facilitating the availability of versatile and multipurpose radiopharmaceuticals.

Rigid and flexible ureteroscopy (URS/RIRS) management of paediatric urolithiasis in a not endemic country

INTRODUCTION

In the last years due to miniaturization of endoscopic instruments and percutaneous surgery, endourology has become very popular in paediatric urinary stone managment. We reported our single-centre experience in retrograde endoscopic procedures in children. Results and complications of URS/RIRS are discussed.

MATERIALS AND METHODS

We retrospectively reviewed our experience in patients ≤ 16 years old affected by urinary stones who underwent URS/RIRS procedures performed by two surgeons with expertise in endourology. A total of 30 renal Units (RUs) underwent endoscopic procedures (URS, RIRS or both). Surgical complications according to the ClavienDindo's classification and stone-free rate were evaluated at 3 months follow-up. Success of URS was defined as stone-free status after single procedure while RIRS success rate was considered as presence of residual stone fragments smaller than 4 mm at first procedure.

RESULTS

The mean age of our patients was 8 years, range 2- 16 years. A total of 30 renal units (RUs) underwent 40 endourological procedures (23 URS and 17 RIRS; 10 children underwent both procedures at the same time). 17/30 (56.6%) RUs were pre-stented before surgery. The stone-free status was achieved in 23/30 renal units treated, with a 76.6% success rate. The remaining 7 patients had residual stones greater than 4 mm and underwent further treatments. After a second surgery the stone-free rate turned out to be 93.3% (28/30 renal units).

CONCLUSIONS

Rigid and flexible ureteroscopy (URS/RIRS) is a reliable technique for treatment of < 2 cm urinary stones in paediatric age group. It shows low rate of major complications and promising results in terms of stone-free rate.

[68Ga]Ga-PSMA-11 PET-CT: Local preliminary experience in prostate cancer biochemical recurrence patients

OBJECTIVES

Clinical approach of prostate cancer (PCa) biochemical recurrence (BCR) is an ever-changing topic. Prostate-specific membrane antigen positron emission tomography ([68Ga]Ga-PSMA-11 PET-CTPSMA PET-CT) has shown good potential in this field. The aim is to evaluate PSMA PET-CT detection rate in PCa BCR and assess its impact on clinical outcome.

MATERIAL AND METHODS

Out of 319 patients with PCa who underwent PSMA PET-CT between October 2015 and June 2019, 70 had developed BCR after treatment with curative intent. Two groups were created: one with BCR after surgery (RP group) (N: 48; 68.6%) and other with BCR after radiotherapy (RT group) (N: 22; 31.4%). Clinical, analytical, pathological and PSMA PET-CT results were evaluated.

RESULTS

Initial age was different between groups (p = 0.008). RP patients were mainly at intermediate risk (85.1% vs 42.9%, p = 0.001) while RT patients were at low risk of recurrence (8.5% vs 47.6%, p = 0.001). In RP and RT groups, PSMA PETCT detected, respectively, pelvic relapse in 31.3% and 63.6%, and extrapelvic relapse in 18.8% and 31.8%. Salvage treatment was performed in 61.9% (n = 26) of RP patients and in 15% (n = 3) of RT patients, p < 0.001. Of RP patients submitted to salvage treatment, 59.1% achieved complete remission. Concerning these patients, local radiotherapy led to complete remission in 68.4% (n = 13). Of RT patients submitted to salvage treatment, two had complete remission and one had partial remission.Concerning detection rate, PSMA PET-CT was positive for pelvic relapse when pre-PET PSA ≥ 0.8 ng/mL (RP) or ≥ 2.3 ng/mL (RT) and for extrapelvic relapse when PSA ≥ 0.4 ng/mL (RP) or ≥ 3.5 ng/mL (RT), p > 0.05.

CONCLUSIONS

Biochemical persistence rate after salvage therapy was similar (30-40%). The cut-off PSA values for pelvic relapse detected on PSMA PET-CT were ≥ 0.8 ng/mL (RP) and ≥ 2.3 ng/mL (RT).

The increased recurrence rate of liver abscess caused by extended-spectrum β-lactamase-producing Klebsiella pneumoniae

The pathogenic bacterium Klebsiella pneumoniae (KP) is the major causative agent of pyogenic liver abscess (PLA). But reports about the prognosis of KP-caused PLA (KPLA) are rare. This study aimed to ascertain the recurrence rate of KPLA after initial treatment and its contributing factors. A total of 110 patients who had first-time episodes of KPLA were included into the study. The average follow-up time was 3.65 ± 2.18 years. Twenty (18.18%) KPLA patients experienced recurrence. Those in the recurrence group had a significantly greater incidence of extended-spectrum β-lactamase (ESBL) production compared with the non-recurrence group (30.0% vs 8.89%, P = 0.018). Diabetes, biliary tract disease, and history of malignancy were not associated with recurrence (all P > 0.05). No difference in the CT characteristics of KPLA (including abscess size, location, whether multilocular, gas production of KPLA, and thrombophlebitis) was found between the two groups. Multivariate regression analysis showed that ESBL production (OR, 6.3; 95% CI, 1.02-38.59; P = 0.04) was an independent risk factor for the recurrence of KPLA. Our findings emphasize that KPLA has a high recurrence rate and ESBL production is an independent risk factor for recurrent KPLA.

Advanced modalities of molecular imaging in precision medicine for musculoskeletal malignancies

Musculoskeletal malignancies consist of a heterogenous group of mesenchymal tumors, often with high inter- and intratumoral heterogeneity. The early and accurate diagnosis of these malignancies can have a substantial impact on optimal treatment and quality of life for these patients. Several new applications and techniques have emerged in molecular imaging, including advances in multimodality imaging, the development of novel radiotracers, and advances in image analysis with radiomics and artificial intelligence. This review highlights the recent advances in molecular imaging modalities and the role of non-invasive imaging in evaluating tumor biology in the era of precision medicine.

Advances in PET Diagnostics for Guiding Targeted Cancer Therapy and Studying In Vivo Cancer Biology

Purpose of the Review

We present an overview of recent advances in positron emission tomography (PET) diagnostics as applied to the study of cancer, specifically as a tool to study in vivo cancer biology and to direct targeted cancer therapy. The review is directed to translational and clinical cancer investigators who may not be familiar with these applications of PET cancer diagnostics, but whose research might benefit from these advancing tools.

Recent Findings

We highlight recent advances in 3 areas: (1) the translation of PET imaging cancer biomarkers to clinical trials; (2) methods for measuring cancer metabolism in vivo in patients; and (3) advances in PET instrumentation, including total-body PET, that enable new methodologies. We emphasize approaches that have been translated to human studies.

Summary

PET imaging methodology enables unique in vivo cancer diagnostics that go beyond cancer detection and staging, providing an improved ability to guide cancer treatment and an increased understanding of in vivo human cancer biology.

Diagnostic value and clinical significance of ultrasound combined with CT in cystic renal cell carcinoma

This study investigated the value and clinical significance of ultrasound combined with CT in the diagnosis of cystic renal cell carcinoma. A total of 85 patients with cystic renal cell carcinoma, who were admitted to the Oncology Department of Yantai Yuhuangding Hospital Affiliated to Qingdao University from December 2015 to April 2017, were selected as the study group, and 70 patients with benign renal cyst, who were examined in Yantai Yuhuangding Hospital Affiliated to Qingdao University, were selected as the benign group. The patients in the two groups were examined by ultrasound and CT. The diagnostic value of ultrasound, CT, and ultrasound combined with CT in cystic renal cell carcinoma was analyzed. The sensitivity of ultrasound combined with CT was significantly higher than that of CT and ultrasound (P<0.05). The specificity and diagnostic coincidence rate of ultrasound combined with CT were significantly higher than those of CT (P<0.05). For unicapsular kidney cancer, there was no significant difference among ultrasound, CT and ultrasound combined with CT in the diagnosis of septum and wall nodule (P>0.05). For polycystic kidney cancer, there was no significant difference among ultrasound, CT and ultrasound combined with CT in the diagnosis of the presence or absence of septum (P>0.05). Ultrasound was significantly better than CT in cyst wall confounding (P<0.05). Ultrasound combined with CT was significantly better than ultrasound in calcification and blood supply of tumors (P<0.05). In conclusion, the accuracy of ultrasound combined with CT is higher than that of ultrasound or that of CT in the diagnosis of cystic renal cell carcinoma, which can be beneficial in accurately carrying out clinical diagnosis, reduce the incidence of missed diagnosis and misdiagnosis caused by a single diagnosis and treatment. Ultrasound combined with CT is good for clinical screening and can guide clinical symptomatic treatment, which is worthy of generalizing in clinic.