Agreement Between 18F-FDG PET/CT and Whole-Body Magnetic Resonance Compared With Skeletal Survey for Initial Staging and Response at End-of-Treatment Evaluation of Patients With Multiple Myeloma

PURPOSE

To compare the agreement between whole-body (WB) magnetic resonance (MR) imaging, 18F-FDG PET/CT, and skeletal survey (SS) in patients with multiple myeloma (MM) for diagnosis, initial staging, response evaluation, and early detection of complications.

METHODS

This is a retrospective cohort study including MM patients who were diagnosed, treated, and followed in 2 institutions. These patients were studied with SS, WB-MR, and/or 18F-FDG PET/CT. We studied bone lesions by anatomical locations and analyzed the concordance between SS and a tomographic technique (WB-MR or 18F-FDG PET/CT) and between both tomographic techniques (WB-MR and PET/CT).

RESULTS

Forty-four MM patients with a mean age of 62.6 years (range, 38-85 years) were included from January 2012 to February 2016. Whole-body MR and 18F-FDG PET/CT found more lesions than SS in every location except in the skull. Concordance between WB-MR and 18F-FDG PET/CT was either good or excellent in most of the locations and in plasmacytoma studies. However, WB-MR was better than 18F-FDG PET/CT in the study of complications (medullar compression and vascular necrosis).

CONCLUSIONS

Our results suggest the study of MM patients should include WB-MR and/or 18F-FDG PET/CT, whereas SS is only useful for the skull. Whole-body MR and 18F-FDG PET/CT are complementary techniques, because both of them show good concordance in almost every location. It is still necessary to individualize the indication of each technique according to patient characteristics.

Novel Experience in Hybrid Tracers: Clinical Evaluation of Feasibility and Efficacy in Using ICG-99mTc Nanotop for Sentinel Node Procedure in Breast Cancer Patients

PURPOSE

The clinical introduction of a radioactive and fluorescent hybrid tracer allowed for preoperative lymphatic mapping and intraoperative real-time fluorescence tracing of the sentinel lymph node (SLN) by a single injection. The aim of this feasibility study is to evaluate the first-in-human use of the hybrid tracer by combining indocyanine green (ICG) and radiocolloid based on Nanotop compound (99mTc Nanotop) for SLN biopsy (SLNB) in breast cancer patients.

METHODS

The day before surgery, ICG-99mTc Nanotop was injected periareolarly in breast cancer patients scheduled for SLNB. Planar lymphoscintigraphic (PL) and SPECT/CT images were then acquired. An intraoperative optonuclear probe was used to detect SLN gamma and fluorescent signals. The harvested SLNs were examined by hematoxylin-eosin staining, and patients were clinically evaluated 1 month after surgery.

RESULTS

Twenty-one consecutive patients were enrolled. The PL and SPECT/CT techniques identified at least 1 SLN in all patients for a preoperative sentinel detection rate of 100%. SPECT/CT revealed 3 additional lymph nodes in the same nodal basin, which had not been visualized on conventional PL (κ = 0.747; P < 0.005). All 30 preoperative SLNs were localized and excised up to 16 hours after injection. The counts measured via gamma tracing showed a very strong correlation with those measured via near-infrared fluorescent tracing (P < 0.005, r = 0.964). No adverse reactions were observed.

CONCLUSIONS

The SLNB technique used with the ICG-99mTc Nanotop tracer resulted to be feasible, reliable, and safe. This hybrid compound allowed us to obtain excellent performance in terms of both preoperative lymphatic mapping and intraoperative SLN detection in breast cancer patients.

Venous Air Embolism Identified by 18F-Fluorocholine Dual-Phase PET/CT

ABSTRACT

A 60-year-old woman with primary hyperparathyroidism with previous nonconclusive imaging studies was referred for 18F-fluorocholine (18F-FCH) PET/CT as part of the preoperative diagnostic imaging workup to localize the adenoma before minimally invasive surgery. 18F-FCH PET/CT with dual time point was performed, acquiring immediately and 60 minutes after 18F-FCH administration. The early images demonstrated possible hyperfunctioning parathyroid tissue in the mediastinum, located in the right upper paratracheal space (region 2R), with an incidental iatrogenic subclavian venous air bubble embolism presenting as high uptake in the early images that disappeared in the late images. No symptomatology was reported during the examination.

Machine learning-based differentiation between multiple sclerosis and glioma WHO II°-IV° using O-(2-[18F] fluoroethyl)-L-tyrosine positron emission tomography

INTRODUCTION

This study aimed to test the diagnostic significance of FET-PET imaging combined with machine learning for the differentiation between multiple sclerosis (MS) and glioma II°-IV°.

METHODS

Our database was screened for patients in whom FET-PET imaging was performed for the diagnostic workup of newly diagnosed lesions evident on MRI and suggestive of glioma. Among those, we identified patients with histologically confirmed glioma II°-IV°, and those who later turned out to have MS. For each group, tumor-to-brain ratio (TBR) derived features of FET were determined. A support vector machine (SVM) based machine learning algorithm was constructed to enhance classification ability, and Receiver Operating Characteristic (ROC) analysis with area under the curve (AUC) metric served to ascertain model performance.

RESULTS

A total of 41 patients met selection criteria, including seven patients with MS and 34 patients with glioma. TBR values were significantly higher in the glioma group (TBRmax glioma vs. MS: p = 0.002; TBRmean glioma vs. MS: p = 0.014). In a subgroup analysis, TBR values significantly differentiated between MS and glioblastoma (TBRmax glioblastoma vs. MS: p = 0.0003, TBRmean glioblastoma vs. MS: p = 0.0003) and between MS and oligodendroglioma (ODG) (TBRmax ODG vs. MS: p = 0.003; TBRmean ODG vs. MS: p = 0.01). The ability to differentiate between MS and glioma II°-IV° increased from 0.79 using standard TBR analysis to 0.94 using a SVM based machine learning algorithm.

CONCLUSIONS

FET-PET imaging may help differentiate MS from glioma II°-IV° and SVM based machine learning approaches can enhance classification performance.

Enhanced antitumor efficacy of lapachol-loaded nanoemulsion in breast cancer tumor model

Lapachol (LAP) is a natural compound with various biological properties, including anticancer activity. However, its clinical application is limited due to the low aqueous solubility and potential adverse side effects. Nanoemulsions are drug delivery systems that can assist in the administration of hydrophobic drugs, increasing their bioavailability and protecting from degradation. Thus, this study aimed to prepare a LAP-loaded nanoemulsion (NE-LAP), and evaluate its antitumor activity. For this purpose, the nanoemulsion was prepared using a hot homogenization method and characterized morphologically by cryogenic transmission electron microscopy (cryo-TEM). Mean diameter, polydispersity index, and zeta potential was evaluated by DLS, encapsulation efficiency was measured by HPLC. Moreover, the short-term storage stability, the drug release and hemolysis in vitro was determined. Additionally, pharmacokinetic, toxicology and toxicity properties of99mTc-NE-LAP were evaluated in a breast cancer (4T1) tumor model. The cryo-TEM showed spherical globules, and the physicochemical characterization of NE-LAP showed a homogeneous stable nanoemulsion with a mean diameter of ∼170 nm, zeta potential of around -20 mV, and encapsulation greater than 85 %. In vitro studies validated that encapsulation did not impair the cytotoxicity activity of LAP. The nanoemulsion was successfully radiolabeled and 99mTc-NE-LAP showed prolonged blood circulation and tumor affinity was confirmed by tumor-to-muscle ratio. Moreover, NE-LAP showed higher antitumor activity than the free drug and the treatment did not result in any signs of toxicity. Therefore, these findings suggest that NE-LAP can be considered an effective strategy for cancer treatment.

Selective internal radiation therapy of hepatic tumors: Morphologic and functional imaging for voxel-based computer-aided dosimetry

Introduction:

Selective Internal Radiation Therapy (SIRT) is used for the treatment of hepatic tumors. The aim of this retrospective study was to compare two dosimetric approaches based on ^99mTc-MAA SPECT/CT and ⁹⁰Y PET/CT, using Simplicit⁹⁰Y^™versus the supplier suggested method of activity calculation.

Material and methods:

A total of 19 patients underwent 21 SIRT after baseline angiography and 99mTc-MAA SPECT/CT, followed by 90Y PET/CT. Overlap between 99mTc-MAA and 90Y-microspheres was quantified with different thresholds isocontours. The perfused volume and tumor absorbed dose were estimated using Simplicit90Y^™ based on SPECT/CT and PET/CT, then compared with the supplier suggested method. These data were related to overall survival to evaluate their prognostic impact.

Results:

The overlap between PET/CT and SPECT/CT was dependent on thresholds, decreasing with an increasing threshold. The overlap between the 99mTc-MAA and 90Y-microspheres biodistributions versus the tumor distribution on morphological imaging was suboptimal, in particular for small tumor volume. The tumor absorbed dose estimated after 90Y PET/CT was not different from tumor absorbed dose estimated after SPECT/CT. The Perfused lobe absorbed dose was significantly lower while the volume of the perfused lobe was significantly higher when estimated by Simplicit90Y^™ compared to the supplier suggested conventional approach. A statistical parameter based on overlap between tumor and 90Y-microspheres distribution as well as tumoral dosimetry was significantly related to the overall survival.

Conclusion:

Post-treatment imaging remains paramount to estimate the irradiation dosimetry, due to an imperfect overlap. The perfused volume could be estimated from functional imaging, given its impact on dosimetry. Finally, survival seems related to tumoral overlap and dosimetry.

The role of sacubitril/valsartan in the treatment of chronic heart failure with reduced ejection fraction in hypertensive patients with comorbidities: From clinical trials to real-world settings

Background:

Sacubitril/valsartan, the first agent to be approved in a new class of drugs called angiotensin receptor neprilysin inhibitors (ARNIs), has been shown to reduce cardiovascular mortality and morbidity compared to enalapril in outpatient subjects with chronic heart failure (HF) and reduced left ventricular ejection fraction (HFrEF). However, there is little real-world evidence about the efficacy of ARNIs in elderly hypertensive patients with HFrEF and comorbidities.

Methods:

In this prospective open-label study, 108 subjects, 54 of them (mean age 78.6 ± 8.2 years, 75.0 % male), with HFrEF (29.8 ± 4.3 %) and New York Heart Association (NYHA) class II-III symptoms were assigned to receive ARNIs twice daily, according to the recommended dosage of 24/26, 49/51, 97/103 mg. Patients were gender- and age-matched with a control arm of patients with HFrEF receiving the optimal standard therapy for HF. The clinic blood pressure (BP), N-terminal pro-B-type natriuretic peptide (NT-proBNP), estimated glomerular filtration rate (eGFR), blood glucose and glycated hemoglobin (HbA1c), uric acid (UA), left ventricular ejection fraction (LVEF) and NYHA class were evaluated at a mean follow-up of 12 months. During the follow-up, the clinical outcomes, including mortality and re-hospitalization for HF, were collected.

Results:

NYHA class significantly improved in the ARNI arm compared to the control (24.9 vs. 6.4 %, shifting from class III to II, and 55.4 vs. 25.2 %, from class II to I, p < 0.05 for all). A significant improvement in LVEF and eGFR levels was found in the ARNI arm compared to controls (42.4 vs. 34.2 %, 73.8 vs. 61.2 mL/min, respectively; p < 0.001 for all). NT-proBNP, clinic systolic and diastolic BP, blood glucose, HbA1c and UA values were reduced in both treatment arms, but they were lower in the ARNI arm compared controls (3107 vs. 4552 pg/mL, 112.2 vs. 120.4 and 68.8 vs. 75.6 mmHg, 108.4 vs. 112.6 mg/dL, 5.4 vs. 5.9 % and 5.9 vs. 6.4 mg/dL, respectively, p < 0.05). Mortality and re-hospitalization for HF was lower in the ARNI arm than controls (20.1 vs. 33.6 % and 27.7 vs. 46.3 % respectively; p < 0.05 for all). Gender differences were not found in either arm. No patients refused to continue the study, and no side effects to the ARNI treatment were observed.

Conclusions:

In elderly patients with HFrEF and comorbidities, ARNI treatment seems effective and safe. The improvement in LVEF and cardiac remodeling, BP, eGFR, serum glucose, UA and HbA1c could be the mechanisms by which ARNIs play their beneficial role on clinical outcomes. However, these results need to be confirmed in studies involving a greater number of subjects, and with a longer follow-up.

Comparison of 99mTc-Labeled Colloid SPECT/CT and Planar Lymphoscintigraphy in Sentinel Lymph Node Detection in Patients with Melanoma: A Meta-Analysis

We compared the detection rate (DR) for sentinel lymph nodes (SLN), the number of SLNs and the subjects with additional SLNs of single-photon emission computed tomography (SPECT/CT) and planar lymphoscintigraphy (PL) in patients with melanoma. Furthermore, we evaluated the impact of SPECT/CT on surgical plans. Articles containing head-to-head comparisons between SPECT/CT and PL were searched in Pubmed/MEDLINE and Scopus. The literature search was updated until December 31st, 2019. DR was calculated on a per patient-based analysis; the studies were pooled by their odds ratios (ORs) with a random effects model to assess the significance of difference (p < 0.05). The number of additional SLNs (calculated as the relative risk) and pooled proportion of patients with additional SLNs were investigated. The pooled ratio of surgical procedures influenced by the SPECT/CT findings was calculated. Seventeen studies with 1438 patients were eligible for the calculation of DR of SPECT/CT and PL. The average DR was 98.28% (95% confidence interval (95% CI): 97.94-99.19%) for the SPECT/CT and 95.53% (95% CI: 92.55-97.77%) for the PL; OR of 2.31 (95% CI: 1.66-4.18, p < 0.001) in favor of the SPECT/CT. There was a relative risk of a higher number of SLNs (1.13) for the SPECT/CT and 17.87% of patients with additional SLNs were detected by SPECT/CT. The average impact of SPECT/CT on surgery resulted in 37.43% of cases. This meta-analysis favored SPECT/CT over PL for the identification of SLNs in patients with melanoma due to a higher DR, reproducibility, number of SLNs depicted, proportion of patients with additional SLNs and the impact on the surgical plan. However, PL remains a good option due to the high values of the DR for SLNs.

A new mobile self-dispensing and administering system for 18F-FDG: evaluation of operator dose reduction

PURPOSE

Recently new mobile systems for dispensing positron emitters have been produced, designed to guarantee dispensing cycles in an aseptic environment. The aim of the present work was to assess the advantage of one of these systems in radiation protection of operators in clinical settings.

METHODS

Recently, in our centre the new self-dispensing system named KARL₁₀₀ by Tema Sinergie was adopted for ¹⁸F-FDG radiopharmaceuticals. The system is associated with an automatic Rad-inject infuser. The system that was previously used was a fixed isolator NMC DSI (Tema Sinergie), equipped with a μDDS-An activity fractioning system, together with a pneumatic post for the syringe delivery. The dosimetric evaluations on both systems were carried out through environmental measurements with an ionisation chamber and with the use of personal dosimeters.

RESULTS

The operations of preparation and administration of ¹⁸F-FDG dose to the patient, with the use of Karl₁₀₀ + RadInject, involve exposures much lower than those obtained by the fixed isolator. The average body exposure of the technician was reduced by 31%, and for the physician by 77%. On the extremities, the equivalent dose to the hands of the technician was reduced by 78%, and for the physician by 96%. Also the additional dosimeters worn by the technician confirmed the estimated environmental assessments.

CONCLUSIONS

The exposures of the working personnel were significantly reduced with the introduction of the new KARL₁₀₀ system.

The sentinel lymph node biopsy technique in papillary thyroid carcinoma: The issue of false-negative findings

BACKGROUND

The management of papillary thyroid carcinoma (PTC) is changed after introduction of sentinel lymph node biopsy (SNB) technique for nodal staging. Some debate still surrounds the accuracy of this procedure in terms of wide heterogeneity of sentinel lymph node detection and false-negative findings.

AIM

to identify the key issues which make it difficult the usefulness of SNB in PTC.

METHODS

A comprehensive computer literature search of meta-analyses published in PubMed/MEDLINE and Cochrane library database until June 30, 2019 was conducted. We used a search algorithm based on this combination of terms: (i) "thyroid neoplasm" or "thyroid cancer" or "thyroid carcinoma" or "thyroid malignancy" or "meta-analysis" or "systematic review") AND (ii) "sentinel lymph node biopsy".

RESULTS

Comparing 4 written meta-analyses published in the literature, the diagnostic performance of SNB technique in PTC has been summarized. Relatively high false-negative rates (FNR) were reported for each SNB methods: vital-dye (VD: 12.7%; 7%; 0-38%), 99mTc-nanocolloid planar lymphoscintigraphy with the use of intraoperative hand-held gamma probes (LS: 11.3%; 16%; 0-40%), combined LS with VD (LS+VD: 0%; 0-17%), LS with the additional contribution of preoperative SPECT/CT (7-8%).

CONCLUSION

Evidence-based data about the diagnostic performance of SNB in PTC are increasing. The nuclear medicine community should reach a consensus on the operational definition of the SLN to better guide the surgeon in identifying the lymph nodes most likely contain metastatic cells. Standardization of SLN identification, removal and analysis are required.

Thermosensitive Nanosystems Associated with Hyperthermia for Cancer Treatment

Conventional chemotherapy regimens have limitations due to serious adverse effects. Targeted drug delivery systems to reduce systemic toxicity are a powerful drug development platform. Encapsulation of antitumor drug(s) in thermosensitive nanocarriers is an emerging approach with a promise to improve uptake and increase therapeutic efficacy, as they can be activated by hyperthermia selectively at the tumor site. In this review, we focus on thermosensitive nanosystems associated with hyperthermia for the treatment of cancer, in preclinical and clinical use.

Long-term effect of the perindopril/indapamide/amlodipine single-pill combination on left ventricular hypertrophy in outpatient hypertensive subjects

BACKGROUND

Most antihypertensive drugs used in monotherapy or in combination therapy reduce the left ventricular mass index (LVMI). However, little is known about the effects on LVMI of a triple fixed-dose combination (TFC) therapy, containing in a single pill an angiotensin-converting enzyme inhibitor (ACEI), a diuretic and a calcium channel blocker (CCB).

METHODS

In this prospective open-label study, 92 patients with essential hypertension were randomized to treatment with a TFC of perindopril/indapamide/amlodipine at different doses or a triple free combination therapy (FCT) including ACEI/diuretic/CCB. Office blood pressure (BP) measurement, 24 h-ambulatory BP monitoring and echocardiography were performed at baseline and during a 14-month follow-up. The BP variability (BPV) over 24 h was calculated as ± standard deviation of the daytime systolic BP. Differences between office and monitored BP and LVMI were evaluated by ANOVA for repeated measures.

RESULTS

A significant BP-lowering effect was observed for both treatments. At follow-up, BPV was reduced in both the treatment groups vs. the baseline (14.0±1.5 vs. 17.0±1.8 and 16.2±2.1 vs. 17.6±2.3, respectively), but it was lower in the TFC vs. the FCT group (14.0±1.5 vs. 16.1±2.2, P < 0.05). LVMI was lower in both the treatment groups, but the change was greater for TFC vs. FCT (-8.3±4.9% vs. -2.0 ±2.1%, P < 0.0001). Left ventricular hypertrophy (LVH) regression was greater in the TFC vs. the FCT group (43.5% vs. 30.4%, P < 0.05).

CONCLUSIONS

Independently of BP values achieved, the antihypertensive TFC therapy was more effective than FCT in LVMI reduction and LVH regression, possibly related to drugs' intrinsic properties and to BPV modulation.

European Association of Nuclear Medicine Practice Guideline/Society of Nuclear Medicine and Molecular Imaging Procedure Standard 2019 for radionuclide imaging of phaeochromocytoma and paraganglioma

PURPOSE

Diverse radionuclide imaging techniques are available for the diagnosis, staging, and follow-up of phaeochromocytoma and paraganglioma (PPGL). Beyond their ability to detect and localise the disease, these imaging approaches variably characterise these tumours at the cellular and molecular levels and can guide therapy. Here we present updated guidelines jointly approved by the EANM and SNMMI for assisting nuclear medicine practitioners in not only the selection and performance of currently available single-photon emission computed tomography and positron emission tomography procedures, but also the interpretation and reporting of the results.

METHODS

Guidelines from related fields and relevant literature have been considered in consultation with leading experts involved in the management of PPGL. The provided information should be applied according to local laws and regulations as well as the availability of various radiopharmaceuticals.

CONCLUSION

Since the European Association of Nuclear Medicine 2012 guidelines, the excellent results obtained with gallium-68 (⁶⁸Ga)-labelled somatostatin analogues (SSAs) in recent years have simplified the imaging approach for PPGL patients that can also be used for selecting patients for peptide receptor radionuclide therapy as a potential alternative or complement to the traditional theranostic approach with iodine-123 (¹²³I)/iodine-131 (¹³¹I)-labelled meta-iodobenzylguanidine. Genomic characterisation of subgroups with differing risk of lesion development and subsequent metastatic spread is refining the use of molecular imaging in the personalised approach to hereditary PPGL patients for detection, staging, and follow-up surveillance.

Folate-coated, long-circulating and pH-sensitive liposomes enhance doxorubicin antitumor effect in a breast cancer animal model

Long circulating pH-sensitive liposomes have been shown to effectively deliver doxorubicin (DOX) to tumors and reduce its toxic effects. Folic acid receptors are upregulated in a wide variety of solid, epithelial tumors, including breast cancer. In order to improve liposomal endocytosis and antitumor activity, folic acid has been added to nanoparticles surfaces to exploit overexpression of folate receptors in tumor cells. The purpose of this study was to evaluate the antitumor activity in vitro and in vivo of long circulating pH-sensitive folate-coated DOX-loaded liposomes (SpHL-DOX-Fol) in a 4T1 breast cancer model system in vitro and in vivo. Biodistribution studies were performed and in vivo electrocardiographic parameters were evaluated. A higher tumor uptake for radiolabeled SpHL-Fol (^99mTc-SpHL-Fol) 4 h after intravenous administration was observed in comparision with non-folate-coated liposomes (^99mTc-SpHL). Antitumor activity showed that SpHL-DOX-Fol treatment led to a 68% growth arrest and drastically reduce pulmonary metastasis foci. Additionally, eletrocardiographic parameters analysis revealed no dispersion in the QT and QTc interval was observed in liposomal treated mice. In summary, this novel multifunctional nanoplatform deomonstrated higher tumor uptake and antitumor activity. SpHL-DOX-Fol represents a drug delivery platform to improve DOX tumor delivery and reduce dose-limiting toxicity.

Diuresis renography in equivocal urinary tract obstruction. A historical perspective

Obstructive nephropathy may be suspected for the incidental detection of dilated renal collecting system at ultrasonography, CT or MRI. A dilated renal collecting dilation (calyco-pelvis or ureteres) might be related 1) to an anatomical variant of the excretory tract without obstruction and, therefore, without consequence on renal function, or 2) to an obstruction/stenosis of the urinary tract that may cause a damage of kidney function. In the present review we annotated the various methods proposed for Diuresis Renography (DR) used with the purpose to make early diagnosis of obstructive nephropathy. First, the F + 20 method (i.e. furosemide 40 mg injected IV 20 min after radiotracer injection) in seated position (sp) (F + 20(sp)) was reported to distinguish between an anatomical dilation from an anatomical obstruction of the urinary tract. It was also suggested to perform DR with the patient in supine or prone position in order to minimize possible furosemide-induced hypotension and patient's movements during exam. Other DR methods were proposed administering furosemide EV to the patient in supine position at different times: F-15 (furosemide injected IV 15 min prior to radiotracer), F0 (furosemide injected contemporary to radiotracer), F + 20 (furosemide injected 20 min after the radiotracer), F-20 and Well Tempered (other than F + 20 this modality requires saline infusion for all duration of the test plus bladder catheterization). Unfortunately, in all the above described DR methods with patientin supine position, despite the furosemide administration, a sensitive slowing down of urinary outflow could be related to the supine position itself of the patient during the examination. Lastly, there are reports of a new DR method based on furosemide IV injection 10 min after radiotracer with the patient in seated position, F+10(sp). This method allows a better timing between hydration (400 mL of water) at 5 min, and the injection of relatively low dose of furosemide (20 mg), thus avoiding side effects as diuretic-induced hypotension and favouring bladder filling, therefore ameliorating patient compliance and reducing equivocal responses.

The impact of infection and inflammation in oncologic 18F-FDG PET/CT imaging

Sites of infection and inflammation can be misleading in oncology PET/CT imaging because these areas commonly show ¹⁸F-FDG activity. Caution in the interpretation must be taken to avoid the misdiagnosis of malignancy. Utilization of both CT findings as well as patient history can help differentiate benign infectious and inflammatory processes from malignancy, although occasionally additional work-up may be required. This article discusses the mechanism of ¹⁸F-FDG uptake in infection and inflammation with illustrative examples.

Influence of PEG coating on the biodistribution and tumor accumulation of pH-sensitive liposomes

Liposomes are lipid vesicles widely used as nanocarriers in targeted drug delivery systems for therapeutic and/or diagnostic purposes. A strategy to prolong the blood circulation time of the liposomes includes the addition of a hydrophilic polymer polyethylene glycol (PEG) moiety onto the surface of the vesicle. Several studies claim that liposome PEGylation by a single chain length or a combination of PEG with different chain lengths may alter the liposomes' pharmacokinetic properties. Therefore, the purpose of this study was to evaluate the influence of PEG on the biodistribution of pH-sensitive liposomes in a tumor-bearing animal model. Three liposomal formulations (PEGylated or not) were prepared and validated to have a similar mean diameter, monodisperse distribution, and neutral zeta potential. The pharmacokinetic properties of each liposome were evaluated in healthy animals, while the biodistribution and scintigraphic images were evaluated in tumor-bearing mice. High tumor-to-muscle ratios were not statistically different between the PEGylated and non-PEGylated liposomes. While PEGylation is a well-established strategy for increasing the blood circulation of nanostructures, in our study, the use of polymer coating did not result in a better in vivo profile. Further studies must be carried out to confirm the feasibility of the non-PEGylated pH-sensitive liposomes for tumor treatment.

Role of 18F-FDG PET/CT in establishing new clinical and therapeutic modalities in lung cancer. A short review

Lung cancer is a fairly common malignancy. An early diagnosis and a reliable staging and re-staging with the aim to detect both local and distant relapse are of utmost importance in planning the therapeutic management. The imaging diagnostic work-up of patients with lung cancer usually includes conventional imaging (chest X-ray, contrast-enhanced CT, bone scan) and more recently ¹⁸F-FDG PET/CT. Great advances in the management of lung cancer are based on the information provided by ¹⁸F-FDG PET/CT, as it supplies both metabolic and anatomic information (better localisation). There is vast evidence in the literature demonstrating its utility in (a) characterising benign versus malignant solitary nodules, (b) staging and re-staging lung cancer, (c) guiding the type of therapy, (d) monitoring treatment response and (e) predicting outcome. In particular, given its specificity in differentiating ¹⁸F-FDG-avid relapse from post-surgical changes or post-radiation fibrosis (which do not take up ¹⁸F-FDG), PET/CT can detect recurrent disease after initial treatment and (being a whole-body technique) has demonstrated high accuracy in the detection of distant metastases or secondary tumours. In conclusion, ¹⁸F-FDG PET/CT can be considered a highly accurate and reliable method for staging and re-staging lung cancer, and is highly effective in guiding personalised therapies.

Effects of plasma glucose levels on regional cerebral 18F-fluorodeoxyglucose uptake: Implications for dementia evaluation with brain PET imaging

Purpose:

Hyperglycemia affects FDG uptake in the brain, potentially emulating Alzheimer’s disease in normal individuals. This study investigates global and regional cerebral FDG uptake as a function of plasma glucose in a cohort of patients.

Methods:

120 consecutive male patients with FDG PET/CT for initial oncologic staging (July-Dee 2015) were reviewed. Patients with dementia, cerebrovascular accident, structural brain lesion, prior oncology treatment or high metabolic tumor burden (recently shown affecting brain FDG uptake) were excluded. 53 (24 nondiabetic) eligible patients (age 65.7 ± 2.8 mean ± SE) were analyzed with parametric computer software, MIMneuro™. Regional Z-scores were evaluated as a function of plasma glucose and age using multi variable linear mixed effects models with false discovery analysis adjusting for multiple comparisons. If the regression slope was significantly (p < 0.05) different than zero, hyperglycemia effect was present.

Results:

There was a negative inverse relationship (p < 0.001) between global brain FDG uptake and hyperglycemia. No regional hyperglycemia effect on uptake were present when subjects were normalized using pons or cerebellum. However, regional hyperglycemia effects were seen (p < 0.047–0.001) when normalizing by the whole brain. No obvious pattern was seen in the regions affected. Age had a significant effect using whole brain normalization (p < 0.04–0.01).

Conclusions:

Cortical variation in FDG uptake were identified when subjects were hyperglycemic. However, these variations didn’t fit a particular pattern of dementia and the severity of the affect is not likely to alter clinical interpretation.

Nanostructured Lipid Carrier Co-loaded with Doxorubicin and Docosahexaenoic Acid as a Theranostic Agent: Evaluation of Biodistribution and Antitumor Activity in Experimental Model

PURPOSE

Nanotheranostic platforms, i.e., the combination of both therapeutic and diagnostic agents on a single platform, are emerging as an interesting tool for the personalized cancer medicine. Therefore, the aim of this work was to evaluate the in vivo properties of a Tc-99m-labeled nanostructured lipid carrier (NLC) formulation, co-loaded with doxorubicin (DOX) and docosahexaenoic acid (DHA), for theranostic applications.

PROCEDURES

NLC-DHA-DOX were prepared busing the hot melting homogenization method using an emulsification-ultrasound and were radiolabeled with Tc-99m. Biodistribution studies, scintigraphic images, and antitumor activity were performed in 4T1 tumor-bearing mice.

RESULTS

NCL was successfully radiolabeled with Tc-99m. Blood clearance showed a relatively long half-life, with blood levels decaying in a biphasic manner (T_1/2 α = 38.7 min; T_1/2 β = 516.5 min). The biodistribution profile and scintigraphic images showed higher tumor uptake compared to contralateral muscle in all time-points investigated. Antitumor activity studies showed a substantial tumor growth inhibition ratio for NLC-DHA-DOX formulation. In addition, the formulation showed more favorable toxicity profiles when compared to equivalent doses of free administered drugs, being able to reduce heart and liver damage.

CONCLUSIONS

Therefore, NLC-DHA-DOX formulation demonstrated feasibility in breast cancer treatment and diagnosis/monitoring, leading to a new possibility of a theranostic platform.

Technetium-99m-labeled lapachol as an imaging probe for breast tumor identification

OBJECTIVE

Breast cancer is a health problem worldwide with high incidence and mortality rates. It is well known that the development of more sensitive and specific diagnostic methods is of great importance since an early diagnosis is essential to successfully treat tumors. Lapachol is a natural compound, belonging to the naphthoquinone group that has been widely used in traditional medicine to treat various illnesses, including cancer. The aim of this study was to evaluate technetium-99m (^99mTc) labeled lapachol as an imaging probe for breast cancer identification.

METHODS

To achieve this purpose, lapachol was labeled with ^99mTc, radiochemical purity and in vitro stability were determined. Blood clearance, in healthy mice, and biodistribution, in 4T1 tumor-bearing mice, were also evaluated.

RESULTS

Lapachol was successfully labeled with ^99mTc, with high values of radiochemical yield (95.9±3.4%). In vitro stability showed that the radiolabeled complex remained stable for up to 24h, with values above 90% for both saline and plasma (95.6±3.6% and 96.4±1.7%, respectively). The radiolabeled complex decays in a biphasic manner, with a half-life of distribution and elimination equal to 3.3 and 50.0min, respectively. Biodistribution and scintigraphic images showed high uptake in organs of excretion (kidneys, liver, and intestine). It could be also noted that tumor uptake was higher than the muscle at all time points. Tumor-to-muscle ratio reaches ∼4.5 at 24h after administration.

CONCLUSION

These findings suggest that ^99mTc-lapachol can be a potential diagnostic agent for breast tumors.

The EANM practical guidelines for sentinel lymph node localisation in oral cavity squamous cell carcinoma

Purpose

Sentinel lymph node biopsy is an essential staging tool in patients with clinically localized oral cavity squamous cell carcinoma. The harvesting of a sentinel lymph node entails a sequence of procedures with participation of specialists in nuclear medicine, radiology, surgery, and pathology. The aim of this document is to provide guidelines for nuclear medicine physicians performing lymphoscintigraphy for sentinel lymph node detection in patients with early N0 oral cavity squamous cell carcinoma.

Methods

These practice guidelines were written and have been approved by the European Association of Nuclear Medicine (EANM) and the International Atomic Energy Agency (IAEA) to promote high-quality lymphoscintigraphy. The final result has been discussed by distinguished experts from the EANM Oncology Committee, and national nuclear medicine societies. The document has been endorsed by the Society of Nuclear Medicine and Molecular Imaging (SNMMI).

These guidelines, together with another two focused on Surgery and Pathology (and published in specialised journals), are part of the synergistic efforts developed in preparation for the “2018 Sentinel Node Biopsy in Head and Neck Consensus Conference”.

Conclusion

The present practice guidelines will help nuclear medicine practitioners play their essential role in providing high-quality lymphatic mapping for the care of early N0 oral cavity squamous cell carcinoma patients.

How to harmonize SUVs obtained by hybrid PET/CT scanners with and without point spread function correction

State of the art point-spread function (PSF) corrections implemented in positron emission tomography/computed tomography (PET/CT) reconstruction improved image quality and diagnostic performance but caused an increase in the standardized uptake value (SUV) compared to a conventional OSEM reconstruction system. The EANM suggested one produce two reconstructions, one optimised for maximum lesion detection and one for semi-quantitative analysis. In this work we investigated an alternative methodology, using a single reconstruction data set together with a post-reconstruction algorithm for SUV harmonization. Data acquisition was performed on a Siemens Biograph mCT system equipped with lutetium oxyorthosilicat crystals, PSF and time-of-flight algorithms and on a General Electric Discovery STE system equipped with BGO crystals. Both a EANM double reconstruction method and a dedicated post-reconstruction algorithm (marketed as EQ-filter) were tested to harmonize the quantitative values of the two PET/CT scanners. For phantom measurements we used a NEMA IQ phantom and a Jaszczak cylindrical phantom equipped with small spheres (lesion to background ratios of 8:1 and 4:1). Several different reconstruction settings were tested in order to provide a general methodology. Data obtained by phantom measurements were validated on seven oncologic patients who performed a one-bed extra acquisition on a different scanner. The evaluation regarded 39 small lesions (diameters: 0.3-2.6 cm) and was performed by two experienced nuclear medicine physicians. The SUV recoveries measured with the PSF reconstruction exceeded those obtained by the OSEM reconstruction with deviations ranging from 16% to 150%. These discrepancies resulted below 7% applying the optimized value of the EQ.filter or the double-reconstruction methods. For each reconstruction setting the optimal value of the EQ.filter was identified in order to minimize these discrepancies. Patient data, analyzed by Wilcoxon statistical test, confirmed and validated phantom measurements. EQ.filter can harmonize SUV values between different PET/CT scanners using a single reconstruction optimized to maximum lesion detectability. In this way, the second reconstruction proposed by EANM/EARL is avoided.

Sentinel lymph node biopsy in small papillary thyroid cancer. A review on novel surgical techniques

PURPOSE

Sentinel lymph node biopsy (SNB) in patients with papillary thyroid carcinoma (PTC) and negative for clinically neck lymph node metastatic involvement (N0) has emerged as a promising minimally invasive procedure to detect metastatic nodes.

METHODS

The MEDLINE database was searched via the PubMed interface on 10 January 2018 for the MeSH headings "sentinel lymph node biopsy" and "thyroid carcinoma".

RESULTS

Vital blue dye, radioisotope, and the combination of both techniques are used in PTC patients. These methods and the emerging role of SPECT/CT are discussed in this review. The sentinel lymph node (SLN) identification rates ranged from 0 to 100% for blue dye, 83 to 100% for radioisotopes, and 66 to 100% for the combination of both techniques, respectively.

CONCLUSIONS

SNB based on radioisotope technique with the use of intraoperative gamma-probe is an accurate and safe method that allows the highest SLN detection rate. There is sufficient evidence to propagate the increasing use of SNB procedure that has the potential to avoid prophylactic lymph node surgery in patients clinically N0.

Effect of Monacolin K and COQ10 supplementation in hypertensive and hypercholesterolemic subjects with metabolic syndrome

INTRODUCTION

Metabolic syndrome (MetS) is a world-wide epidemic disease with an increased risk of morbidity and mortality. Treatment strategies of MetS include pharmacologic and non-pharmacologic interventions and in this respect a relevant role has been shown for nutraceutical compounds (NCs). The aim of this study was to investigate the efficacy and safety of NCs incorporated with diet and lifestyle management versus diet alone, in lowering blood pressure (BP) values and improving lipid and glucose profile, in a group of hypertensives and hyper-cholesterolemic patients with MetS.

METHODS

104 subjects with MetS (mean age 57.4 ± 8.8 years, 51% males) without history of cardio-vascular (CV) diseases were enrolled in the study. 52 subjects were treated with a once-daily oral formulation of a NCs containing red yeast rice and coenzyme Q10 added to their diet for 2 months and were compared with the 52 patients following a diet program. Differences in BP, serum total cholesterol (TC), low- and high-density-lipoprotein cholesterol (LDLC and HDLC), triglycerides (TG) and glucose values were compared by analysis of variance.

RESULTS

A significant reduction of BP, TC, TG, LDLC and glucose levels was observed in both treatment groups. However, a greater reduction of systolic BP (-5.2 vs. -3.0 mmHg), diastolic BP (-4.9 vs. 2.9 mmHg), total cholesterol (-17.2%), LDLC (-21.8%), TG (-16.0%) and serum glucose (-3.4%) was observed in the treatment group relative to the control (p < 0.001 for all); HDLC remained unchanged (p = N.S.). Gender difference was not found in either group (p = N.S.).

CONCLUSIONS

In patients with MetS, NC supplementation was safe, well tolerated and effective in improving clinic BP, lipid and glucose profile.

99MTc-mibi Radio-guided Surgery in Primary Hyperparathyroidism: A Prospective Study of 128 Patients

Aims and study design

We investigated the role of an intraoperative gamma probe (IGP) technique in 128 patients with primary hyperparathyroidism (HPT). The patients were evaluated before surgery by 99mTcO4/MIBI scintigraphy and neck ultrasound and then operated on by the same surgical team. The IGP technique consisted of the injection of a low dose (37 MBq) of 99mTc-MIBI in the operating room shortly before the start of surgery. Quick parathyroid hormone (QPTH) was routinely measured during the operation.

Results

In 94/97 patients (96.9%) with a preoperative diagnosis of solitary parathyroid adenoma (PA) minimally invasive radioguided surgery (MIRS) was successfully performed; in the other 3/97 patients (3.1%) conversion to bilateral neck exploration (BNE) was required because of the intraoperative diagnosis of parathyroid carcinoma in two cases and multiglandular disease (MGD) in one. MIRS was successfully performed also in 23 patients who had undergone previous thyroid or parathyroid surgery. In 31 patients with a preoperative diagnosis of MGD (n = 5) or concomitant nodular goiter (n = 26) the IGP technique was used during a bilateral neck exploration. Among these patients IGP was useful in localizing an ectopic parathyroid gland in the thymus in one case of MGD and a PA located deep in the neck (n = 2) or ectopic at the carotid bifurcation (n = 1) in three cases with nodular goiter. However, in several other patients with nodular goiter it was difficult for the probe to distinguish intraoperatively between thyroid nodules and PA located close to the thyroid gland.

Conclusions

It can be concluded that a) in primary HPT patients with a high likelihood (according to scintigraphic and ultrasound findings) of being affected by a single PA and with a normal thyroid gland, the IGP technique appears useful in MIRS; b) a 99mTc-MIBI dose as low as 37 MBq appears to be adequate to perform MIRS; c) the measurement of QPTH is strongly recommended in HPT patients selected for MIRS to confirm the radicality of parathyroidectomy; d) MIRS can be useful also in HPT patients who underwent previous parathyroid or thyroid surgery to limit the surgical trauma of reoperation and minimize complications; e) with the exception of PAs located at ectopic sites or deep in the neck, the IGP technique does not seem to be recommendable in HPT patients with concomitant nodular goiter.

A Simplified Procedure for Continuous Intraoperative External Monitoring of Systemic Leakage during Isolated Limb Perfusion

Aims

Isolated limb perfusion (ILP) with high doses of an alkylating agent alone or in combination with tumor necrosis factor (TNF) in hyperthermic conditions (HAP) has been proposed for the treatment of locoregional tumors. A critical step in ILP/HAP is accurate monitoring of systemic leakage to prevent the toxic effects of chemotherapy, and in particular of TNF. Ten percent systemic leakage from the perfusion circuit is considered the maximum acceptable leakage. In this study we report our experience of a new leakage monitoring system.

Materials and methods

This new simplified procedure is based on the use of 99mTc-labeled soluble human serum albumin (HSA) and a hand-held gamma probe as detector. The procedure consists of the following steps: 1) A standardized 99mTc-HSA dose of 0.5 MBq/kg body weight is injected into the perfusion circuit before chemotherapy/TNF perfusion, and a hand-held gamma probe (IGP) is placed over the precordial area in a zone that was marked on the skin during a simulation test; 2) 48-72 hours before ILP/HAP a complete simulation test is performed with a 99mTc-HSA dose corresponding to 10% of the total dose calculated for the patient's body weight; 3) during the simulation test the maximum countrate zone on the precordial area is detected by IGP and marked on the patient's skin; 4) a 60-min curve of effective 99mTc-HSA radioactivity decay (physical and biological) is calculated and fitted; 5) to compare external counting with the effective circulating radioactivity, patient blood samples and circuit blood samples are taken every five minutes during ILP/HAP and measured by a laboratory gamma counter and very convenient thanks to the favorable characteristics of IGP. The placed in the operating room.

Results

External counting with a hand-held gamma probe was easy to perform time/activity curves obtained during simulation tests showed a regular and constant effective decay with a mean decay rate of 30% at 60 minutes compared to baseline values. The external measurements obtained by IGP proved to be well correlated with blood samples measured in vitro by a laboratory gamma counter. The results of this procedure, in particular the data of the simulation test for each patient, allowed us to correct the limit of 10% maximum leakage during ILP/HAP in accordance with the time/activity curve.

Conclusions

Although 99mTc-HSA has some unfavorable characteristics, it offers many advantages over 131I-HSA. The procedure proposed by us, which was based on the use of an IGP and 99mTc-HAS at a standardized dose of 0.5 MBq/kg body weight and on an individual simulation test for each patient performed 48 hours before ILP/HAP, proved to be simple and accurate in monitoring systemic leakage during ILP/HAP anticancer therapy.

The Role of Fluorine-18-Deoxyglucose (Fdg) Positron Emission Tomography (Pet) Whole Body Scan (Wbs) in the Staging and Follow-Up of Cancer Patients: Our First Experience

We report the results of FDG PET whole body scan in 75 cancer patients in whom tumor extent was defined by surgical, histological or cytological findings and clinical follow-up. Twenty-five had malignant lymphomas, 24 lung carcinomas, and 26 other types of solid tumors. Twenty-three patients were evaluated at disease onset, before therapy, and 37 at the moment of tumor recurrence; the remaining 15 patients were in complete remission after treatment and were taken as controls. Visual and quantitative PET results were compared with conventional imaging (US, CT scan and/or MRI, and Tc99m MDP bone scan).

In the 60 patients with active disease, PET as well as conventional imaging were able to locate the primary tumor in all 23 patients studied at disease onset. However, with regard to lymph node and distant metastases, PET provided the same information as conventional imaging in 31 cases (51.6%), but revealed further neoplastic foci in 29 cases (48.4%), 21 in lymph nodes and 8 at distant sites. The sensitivity of PET, in comparison with conventional imaging, was 100% versus 100% for the detection of the primary tumor, 97.6% versus 55.8% for the localization of node metastases, and 100% versus 55.5% for the visualization of distant metastases. The specificity, calculated in the group of 15 disease-free patients, was 100% for PET and 86.6% for conventional imaging. The therapeutic approach was modified in 12 patients (20%) on the basis of the PET results. Furthermore, in 14 cases (23.3%) with advanced disease, PET provided complete information on tumor spread, otherwise obtainable only by taking together the results of all other diagnostic procedures. Our data indicate a higher accuracy of FDG PET whole body scan compared to conventional imaging techniques in the evaluation of metastatic spread both at initial diagnosis and during follow-up, with an important impact on therapeutic decision-making. Moreover, by providing complete information on tumor spread in some cases, PET can become a profitable tool in terms of cost reduction.

Favorable Long Term Results in Patients with Small Differentiated Thyroid Cancer not Treated with Radioiodine

Data on a group of 110 patients with differentiated thyroid cancer not treated by radioiodine are reported. Most of them had intrathyroid (stage I) papillary or capsuled follicular cancer of less than 3 cm diameters. They all received thyroxine at TSH suppressive doses. The follow-up ranged between 4 and 25 years, mean 8.7. No patient died of tumor. Two very old patients died free of disease. Four recurrences occurred, within 8 years, all in patients over 45 years, all local or nodal, all papillary, 3 out of 4 after total thyroidectomy. This study shows that radioiodine therapy may be avoided and that lobectomy may be sufficient in patients under 45 years with small papillary or capsuled follicular cancer.

High Prevalence of Occult Papillary Thyroid Carcinoma in a Surgical Series for Benign Thyroid Disease

In a surgical series of 277 consecutive patients operated on the thyroid for benign diseases, a high prevalence rate (10.5%) of occult papillary carcinoma was found by means of an accurate histologic examination. Indications for surgery were euthyroid multinodular goiter in 25 patients, autonomously hyperfunctioning adenoma in 2 and Graves’ disease in 2 patients. Neoplastic foci were unilaterally found in 25 cases but multifocally in 6 and bilaterally in 4 cases: the diameters ranged from 2-10 mm. After operation (14 subtotal and 15 total thyroidectomies), all patients received TSH-suppressive doses of T4. At a mean follow-up of 5.6 years, neither local recurrences nor lymph node or distant metastases had occurred; no patient died of the tumor. In keeping with other surgical and autopsy series, the prevalence of occult thyroid carcinoma in a normal population is calculated to be about 5-10%, whereas it is known that the prevalence of clinically evident thyroid cancer is only 0.05%. This means that only 1-2% of occult carcinomas may evolve in an overt tumor during life. In view of such an epidemiologic difference and the favorable course of our patients, although the mean follow-up is rather short, we suggest that lobectomy plus T4 treatment may be considered an adequate therapeutic approach in patients with occult papillary thyroid carcinoma.

Distant Metastases in Differentiated Thyroid Cancer: Long-term Results of Radioiodine Treatment and Statistical Analysis of Prognostic Factors in 214 Patients

Long-term results and statistical analysis of prognostic factors in a series of 214 patients with distant metastases from differentiated thyroid cancer (DTC) are reported here. These 214 were part of a total series of 1457 patients with DTC referred to our center from 1967 to 1987. All patients underwent surgery and 131-I therapy and were treated with TSH suppressive doses of thyroid hormones. After a mean follow-up of 7.3 years including clinical, scintigraphic, radiological and laboratory investigations, 24.4% of patients were alive without disease, 36.5% alive with disease, 1.8% dead without disease and 37.3% dead with disease. One of the main factors influencing the survival in our series was 131-I uptake (RIU) by metastatic tissue. No case of complete remission of disease was observed among patients with nonfunctioning metastases. Another important factor was the site of metastases, patients with bone metastases having the worst prognosis. The patient's age at diagnosis represented another important factor for survival; patients over 40 years, particularly those over 60 years had a bad prognosis. A clear interrelation was found among the factors advanced age, nonfunctioning metastases and bone metastases. Patients with these last clinical features were considered to be at high risk and generally had a fatal outcome. Another significant prognostic factor revealed by univariate analysis was the histologic type. Patients with follicular tumor showed a poorer prognosis in comparison to papillary tumor. When multivariate analysis was applied, the factors age at diagnosis, site of metastases and RIU proved to have a significant influence on survival, but not the histologic type. Lastly, the relative rate of males was higher in the group of patients with metastases in comparison to the whole series of DTC patients. Despite this, the factor sex did not influence survival.

Sentinel Node Biopsy in Cutaneous Melanoma Patients: Technical and Clinical Aspects

The role of the patent blue dye (PBD) technique and intraoperative probe-guided lymphoscintigraphy (LS) in detecting the sentinel node (SN) was investigated in a group of 130 consecutive stage I cutaneous melanoma patients. The preoperative workup included high-resolution US scanning and LS performed 15–18 hours before surgery. On the basis of preoperative LS, in the group of examined patients a total of 143 lymphatic drainage basins were identified and surgically explored: 41.6% in the axilla, 52.8% in the groin, and 5.6% in the head/neck. A total of 228 SNs were intraoperatively detected and removed; 110 lymphatic basins contained histologically negative SNs, while 33 basins had metastatic SNs. The sensitivity for SN detection using PBD alone was 93%, while it was 100% when PBD was combined with intraoperative LS. Preoperative and intraoperative LS appears to be a highly sensitive technique for SN detection in cutaneous melanoma patients. Furthermore, in view of the limited skin incision when radioguided surgery is performed, SN biopsy could be feasible under local anesthesia.

Current Role of 111In-DTPA-Octreotide Scintigraphy in Diagnosis of Thymic Masses

Aims and background

Thymic tumors (thymomas and thymic carcinomas) represent 50% of all mediastinal tumors. Thymomas usually express high levels of somatostatin receptors, which enable in vivo imaging with 111In-DTPA-octreotide (OctreoScan®). The aim of this study was to further investigate the role of radionuclide techniques in the diagnosis, staging and follow-up of these tumors.

Methods

Eight patients (5 women, 3 men, age range 35–79 years; mean ± SD 56.1 ± 15.8 years) entered the study. In 4 patients, myasthenia gravis was the presenting symptom. 111In-DTPA-octreotide scan was performed within 3 weeks after contrast enhanced CT and/or MRI. Planar and tomographic images were acquired within 24 hours of the injection of 111 MBq OctreoScan. The scintigraphic results were defined in correlation with the histological findings.

Results

Histology revealed thymoma in 3 patients, thymic carcinoma in 1, insular carcinoma of presumably thymic origin in 1, thymic carcinoid in 1, and thymic hyperplasia in 2 patients. Two thymomas were at stage I, 1 thymoma and 1 thymic carcinoma at stage II, 1 insular carcinoma of presumably thymic origin at stage IV, and 1 thymic carcinoid at stage IV. OctreoScan consistently accumulated in primary and/or metastatic sites of thymic tumors while no radiotracer uptake was detected in the 2 patients with benign thymic hyperplasia. In 1 patient with a very large mediastinal mass (13 cm in largest diameter) and multiple metastatic deposits in the lungs, OctreoScan scintigraphy showed a large area of pathological uptake in the anterior mediastinum and a small area of focal uptake in the cervical-dorsal region of the right lung corresponding to a lymph node expressing somatostatin receptors.

Conclusions

OctreoScan is avidly taken up by thymic tumors, enabling the diagnosis of these tumors and a better evaluation of their extension. It does not accumulate in thymic hyperplasia, thus allowing the differential diagnosis between these 2 pathological conditions. In patients affected by myasthenia gravis, OctreoScan scintigraphy can play an important role in characterizing thymic masses.

Fludeoxyglucose F 18 PET/CT Assessment of Ovarian Cancer

Ovarian cancer is one of the most common gynecologic cancers and one of the leading causes of cancer death in women. It is often asymptomatic in early stages, and thus most patients are diagnosed when it is of advanced stage. For these reasons, the role of biomarkers and tomographic imaging is crucial. Fludeoxyglucose F 18 PET/CT is a useful imaging modality in different clinical settings of the disease, overcoming some limits of conventional imaging and influencing prognosis and therapeutic approaches. PET/MR imaging is an emerging modality, and its potential role remains to be explored.

Minimally invasive radio-guided parathyroidectomy on a group of 452 primary hyperparathyroid patients

The aim of this study was to investigate the efficacy of minimally invasive radio-guided parathyroidectomy (MIRP) in primary hyperparathyroid (PHPT) patients. Patients, methods: 452 consecutive PHPT patients were evaluated. Inclusion criteria for MIRP were (a) evidence at scintigraphy of a solitary parathyroid adenoma (PA); (b) a clear sestamibi uptake in the PA; (c) the absence of concomitant thyroid nodules; (d) no history of familial HPT or MEN; (e) no history of previous neck irradiation. Intra-operative protocol consisted of the injection of a low 37 MBq sestamibi dose in the operating suite 10 min before surgery. A hand held 11-mm collimated gamma probe was used. Quick PTH (QPTH) was routinely measured. Results: 344 out of the 452 patients met the inclusion criteria, and MIRP was successfully performed in 321 of them (93.3%). No major intra-operative complication was recorded. MIRP required a mean operative time of 32 min, and a mean hospital stay of 1.2 d. The parathyroid to background ratio (P/B) calculated by the probe was well correlated with the P/B calculated by sestamibi SPECT (r = 0.91; p <0.01), while no significant correlation was found between the probe-calculated P/B and the P/B calculated at planar sestamibi scan. Conclusions: In our experience: a) an accurate preoperative localising imaging protocol based on planar and SPECT sestamibi scan, and neck US is effective in selecting PHPT patients for MIRP, b) the P/B calculated by sestamibi SPECT seems able to predict the probe-calculated P/B more accurately than the P/B calculated at planar scan, c) the low 37 MBq sestamibi dose protocol proved to be a safe and effective approach to perform MIRP.

Paclitaxel-loaded folate-coated long circulating and pH-sensitive liposomes as a potential drug delivery system: A biodistribution study

A range of antitumor agents for cancer treatment is available; however, they show low specificity, which often limit their use. Recently, we have reported the preparation of folate-coated long-circulating and pH-sensitive liposomes (SpHL-folate-PTX) loaded with paclitaxel (PTX), an effective drug for the treatment of solid tumors, including breast cancer. The purpose of this study was to prepare and characterize SpHL-PTX and SpHL-folate-PTX radiolabeled with technetium-99m (^99mTc). Biodistribution studies and scintigraphic images were performed after intravenous administration of ^99mTc-PTX, ^99mTc-SpHL-PTX and ^99mTc-SpHL-folate-PTX into healthy and tumor-bearing mice. High radiochemical purity (>98%) and in vitro stability (>90%) were achieved for both liposome formulations. The pharmacokinetic properties of ^99mTc-SpHL-DTPA-PTX and ^99mTc-SpHL-folate-DTPA-PTX decreased in a monophasic manner showing half-life of 400.1 and 541.8min, respectively. Scintigraphic images and biodistribution studies showed a significant uptake in liver, spleen and kidneys, demonstrating these routes as way for excretion. At 8h post-injection, the liposomal tumor uptake was higher than ^99mTc-PTX. Interesting, 4h after administration, the liposome folate coated showed higher tumor-to-muscle ratio than ^99mTc-SpHL-DTPA-PTX and ^99mTc-PTX. In conclusion, the liposomal systems, showed high tumor uptake by scintigraphic images, especially the ^99mTc-SpHL-folate-DTPA-PTX that showed a sustained and higher tumor-to-muscle ratio than non-functionalized liposome, which indicate its feasibility as a PTX delivery system to folate positive tumors.

pH-Sensitive, Long-Circulating Liposomes as an Alternative Tool to Deliver Doxorubicin into Tumors: a Feasibility Animal Study

PURPOSE

Therapeutic agents used in chemotherapy have low specificity leading to undesired severe side effects. Hence, the development of drug delivery systems that improve drug specificity, such as liposome moieties, is an alternative to overcome chemotherapy limitations and increase antitumor efficacy. In this study, the biodistribution profile evaluation of pH-sensitive long-circulating liposomes (SpHL) containing [^99mTc]DOX in 4T1 tumor-bearing BALB/c mice is described.

PROCEDURES

[^99mTc]DOX was radiolabeled by direct method. Liposomes were prepared and characterized. [^99mTc]DOX was encapsulated into liposomes by freezing and thawing. Circulation time for SpHL-[^99mTc]DOX was determined by measuring the blood activity from healthy animals. Biodistribution studies were carried out in tumor-bearing mice at 1, 4, and 24 h after injection.

RESULTS

Blood levels of the SpHL-[^99mTc]DOX declined in a biphasic manner, with an α half-life of 14.1 min and β half-life of 129.0 min. High uptake was achieved in the liver and spleen, due to the macrophages captured. Moreover, tumor uptake was higher than control tissue, resulting in high tumor-to-muscle ratios, indicating higher specificity for the tumor area.

CONCLUSION

[^99mTc]DOX was successfully encapsulated in liposomes. Biodistribution indicated high tumor-to-muscle ratios in breast tumor-bearing BALB/c mice. In summary, these results showed the higher accumulation of SpHL-[^99mTc]DOX in the tumor area, suggesting selective delivery of doxorubicin into tumor.

The role of radionuclide probes for monitoring anti-tumor drugs efficacy: A brief review

Despite recent advances in the development of new therapeutic agents and diagnostic imaging modalities, cancer is still one of the main causes of death worldwide. A better understanding of the molecular signature of cancer has promoted the development of a new generation of anti-cancer drugs and diagnostic agents that specifically target molecular components such as genes, ligands, receptors and signaling pathways. However, intrinsic heterogeneity of tumors has hampered the overall success of target therapies even among patients with similar tumor types but unpredictable different responses to therapy. In this sense, post-treatment response monitoring becomes indispensable and nuclear medicine imaging modalities could provide the tools for an early indication of therapeutic efficacy. Herein, we briefly discuss the current role of PET and SPECT imaging in monitoring cancer therapy together with an update on the current radiolabeled probes that are currently investigated for tumor therapy response assessment.