Whole body planar and 3D quantitative imaging after 177Lu-DOTATATE on CZT SPECT/CT device with MEHRS collimator. First report.

Lutetium-177 (177Lu)-based post-therapeutic imaging allows visualization of treated lesions andabsorbed dose measurement. There is an increasing number of cadmium-zinc-telluride (CZT) gamma-cameras in nuclear medicine departments but until now these devices were not adapted to the medium-energy emission of 177Lu photons. We present here in the first reported images acquired with a new collimator designed for CZT gamma-camera compared to a conventional sodium iodide (NaI) (Tl) gamma-camera. Post-therapeutic 177Lu-DOTATATE imaging on a CZT device with a medium energy high resolution (MEHRS)-collimator are promising and support the widespread of both 177Lu-based peptide-receptor radionuclide therapy (PRRT) and CZT gamma-cameras.

Extended liver venous deprivation before major hepatectomy induces marked and very rapid increase in future liver remnant function.

OBJECTIVE: The aim of this study was to assess the safety and efficacy of extended liver venous deprivation (eLVD), i.e. combination of right portal vein embolisation and right (accessory right) and middle hepatic vein embolisation before major hepatectomy for future remnant liver (FRL) functional increase. METHODS: eLVD was performed in non-cirrhotic patients referred for major hepatectomy in a context of small FRL (baseline FRL <25% of the total liver volume or FRL function <2.69%/min/m2). All patients underwent 99mTc-mebrofenin hepatobiliary scintigraphy (HBS) and computed tomographic evaluations. RESULTS: Ten consecutive patients underwent eLVD before surgery for liver metastases (n = 8), Klatskin tumour (n = 1) and gallbladder carcinoma (n = 1). FRL function increased by 64.3% (range = 28.1-107.5%) at day 21. In patients with serial measurements, maximum FRL function was at day 7 (+65.7 ± 16%). The FRL volume increased by +53.4% at 7 days (+25 ± 8 cc/day). Thirty-one days (range = 22-45 days) after eLVD, 9/10 patients were resected. No post-hepatectomy liver failure was reported. Two grade II and one grade III complications (Dindo-Clavien classification) occurred. No patient died with-in 90 days following surgery. CONCLUSIONS: eLVD is safe and provides a marked and very rapid increase in liver function, unprecedented for an interventional radiology procedure. KEY POINTS: • eLVD is safe • eLVD provides a marked and very rapid increase in liver function • After eLVD, the FRL-F increased by 64.3% (28.1-107.5%) at day 21 • After eLVD, the maximum FRL-F was obtained at day 7 (+65.7 ± 16%) • After eLVD, the FRL volume increased by +53.4% at 7 days (+25 ± 8 cc/day).

In myotonic dystrophy type 1 reduced FDG-uptake on FDG-PET is most severe in Brodmann area 8.

BACKGROUND: In myotonic dystrophy type 1 (DM1), only one FDG-PET study used statistical parametric mapping (SPM) showing frontal reduced FDG-uptake. Our aim was to 1) identify the FDG-PET area with the most severe reduced FDG-uptake using SPM8 in a larger group of patients 2) assess potential correlation between CTG-numbers and FDG-PET. METHODS: FDG-PET was performed in 24 patients and compared to 24 controls. Pearson's correlation was used to analyse correlation. RESULTS: SPM8 revealed Brodmann area 8 as the area with the most severe reduced FDG-uptake. Weak, although not statistically significant, correlation was observed between CTG-numbers and reduced FDG-uptake in Brodmann area 8. CONCLUSION: In DM1, Brodmann area 8 is the area with the most severe reduced FDG-uptake on FDG-PET. Brodmann area 8 reduced FDG-uptake is correlated -although weakly- to CTG-repeat numbers.

[68Ga]Ga-FAPI-46 synthesis on a GAIA® module system: Thorough study of the automated radiolabeling reaction conditions.

The influence of several parameters involved in the 68Ga radiolabeling of FAPI-46 was studied at the scale of the automated reaction. Among the buffers tested, HEPES 0.3 M pH 4 allowed both high radiochemical purity (RCP) and radiochemical yield (RCY), without prepurification of 68Ga but after final purification of [68Ga]Ga-FAPI-46 on a C18 cartridge. A longer reaction time did not show significant benefit on the RCP, while higher loads of FAPI-46 and gentisic acid as anti-radiolysis compound allowed better RCY.

Absorbed Dose-Response Relationship in Patients with Gastroenteropancreatic Neuroendocrine Tumors Treated with [177Lu]Lu-DOTATATE: One Step Closer to Personalized Medicine.

[177Lu]Lu-DOTATATE has been approved for progressive and inoperable gastroenteropancreatic neuroendocrine tumors (GEP-NETs) that overexpress somatostatin receptors. The absorbed doses by limiting organs and tumors can be quantified by serial postinfusion scintigraphy measurements of the γ-emissions from 177Lu. The objective of this work was to explore how postinfusion [177Lu]Lu-DOTATATE dosimetry could influence clinical management by predicting treatment efficacy (tumor shrinkage and survival) and toxicity. Methods: Patients with GEP-NETs treated with [177Lu]Lu-DOTATATE between 2016 and 2022 and who underwent dosimetry were included. Absorbed doses were calculated for healthy organs (liver, kidneys, bone marrow, and spleen) and tumors using PLANET Dose and the local energy deposition method based on serial posttreatment SPECT/CT. Up to 5 lesions per site were selected and measured on images collected at baseline and 3 mo after treatment end (measurement masked to the somatostatin receptor imaging uptake). For toxicity assessment, laboratory parameters were regularly monitored. Clinical data, including time to death or progression, were collected from the patients' health records. Correlations between absorbed doses by organs and toxicity and between absorbed doses by lesions and tumor volume variation were studied using regression models. Results: In total, 35 dosimetric studies were performed in patients with mostly grade 2 (77%) tumors and metastases in liver (89%), lymph nodes (77%), and bone (34%), and 146 lesions were analyzed: 1-9 lesions per patient, mostly liver metastases (65%) and lymph nodes (25%). The median total absorbed dose by tumors was 94.4 Gy. The absorbed doses by tumors significantly decreased between cycles. The absorbed dose by tumors was significantly associated with tumor volume variation (P < 0.001) 3 mo after treatment end, and it was a significant prognostic factor for survival. Toxicity analysis showed a correlation between the decrease of hematologic parameters such as lymphocytes or platelet concentrations and the absorbed doses by the spleen or bone marrow. The mean absorbed dose by the kidneys was not correlated with nephrotoxicity during the studied period. Conclusion: In patients treated with [177Lu]Lu-DOTATATE for GEP-NETs, tumor and healthy organ dosimetry can predict survival and toxicities, thus influencing clinical management.

225Ac-Labeled Somatostatin Analogs in the Management of Neuroendocrine Tumors: From Radiochemistry to Clinic.

The widespread use of peptide receptor radionuclide therapy (PRRT) represents a major therapeutic breakthrough in nuclear medicine, particularly since the introduction of 177Lu-radiolabeled somatostatin analogs. These radiopharmaceuticals have especially improved progression-free survival and quality of life in patients with inoperable metastatic gastroenteropancreatic neuroendocrine tumors expressing somatostatin receptors. In the case of aggressive or resistant disease, the use of somatostatin derivatives radiolabeled with an alpha-emitter could provide a promising alternative. Among the currently available alpha-emitting radioelements, actinium-225 has emerged as the most suitable candidate, especially regarding its physical and radiochemical properties. Nevertheless, preclinical and clinical studies on these radiopharmaceuticals are still few and heterogeneous, despite the growing momentum for their future use on a larger scale. In this context, this report provides a comprehensive and extensive overview of the development of 225Ac-labeled somatostatin analogs; particular emphasis is placed on the challenges associated with the production of 225Ac, its physical and radiochemical properties, as well as the place of 225Ac-DOTATOC and 225Ac-DOTATATE in the management of patients with advanced metastatic neuroendocrine tumors.

Comparison of the Discovery A and Stratos DR densitometers for assessing whole-body and regional bone mineral density and body composition.

PURPOSE: The agreement between the Stratos DR and Discovery A densitometers was assessed for measurements of whole-body (WB) and regional fat mass (FM), fat-free soft tissue (FFST) and bone mineral density (BMD). Moreover, the precision of the Stratos DR was also evaluated. METHODS: Fifty participants (35 women, 70%) were measured consecutively, once on the Discovery A and once on the Stratos DR. In a subgroup of participants (n = 29), two successive measurements with the Stratos DR were also performed. RESULTS: FM, FFST and BMD measured with the two devices were highly correlated, with a coefficient of correlation ranging from 0.80 to 0.99. Bland-Altman analyses indicated significant bias between the two devices for all measurements. Thus, compared to the Discovery A, the Stratos DR underestimated WB BMD and WB and regional FM and FFST, with the exception of trunk FM and visceral adipose tissue (VAT), which were overestimated. Precision error for the Stratos DR, when expressed as root mean square-coefficient of variation (RMS-CV%) for FM, was 1.4% for WB, 3.0% for the gynoid and android regions, and 15.9% for VAT. The RMS-CV% for FFST was 1.0% for WB. The root mean square of standard deviation for WB BMD was 0.018 g/cm², corresponding to a 1.4% CV. The least significant change was 0.050 g/cm² (SD), and 4.0% was considered to be a significant biological change. CONCLUSIONS: Differences between the Stratos DR and Discovery A measurements are significant and require the use of translational cross-calibration equations. For most of the BMD and body composition parameters, our results demonstrated good Stratos DR precision.

Clinical Pharmacokinetics of Radiopharmaceuticals from SPECT/CT Image Acquisition by Contouring in Patients with Gastroenteropancreatic Neuroendocrine Tumors: Lu-177 DOTATATE (Lutathera®) Case.

BACKGROUND AND OBJECTIVE: Lu-177 DOTATATE (Lutathera®) is a radiolabeled analog of somatostatin administered intravenously in patients with somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumors. Biodistribution of Lu-177 DOTATATE in tumor and healthy tissues can be monitored by serial post-injection scintigraphy imaging. Patient exposure to the drug is variable with the recommended fixed dosage, and hence there is a variable response to treatment. The aim of this work was to study the pharmacokinetics of Lu-177 DOTATATE by a population modeling approach, based on single-photon emission computed tomography (SPECT)/computed tomography (CT) images used as surrogate of plasma concentrations to study the interindividual variability and finally optimize an individual dosage. METHODS: From a retrospective study, SPECT/CT images were acquired at 4 h, 24 h, 72 h, and 192 h postadministration. From these images, volumic activities were calculated in blood and bone marrow. An individual non-compartmental pharmacokinetic analysis was performed, and the mean pharmacokinetic parameters of each tissue were compared together and with reference data. Blood volumic activities were then used to perform a population pharmacokinetic analysis (NONMEM). RESULTS: The pharmacokinetic parameters (non-compartmental analysis) obtained from blood (clearance [CL] = 2.65 L/h, volume of distribution at steady state [Vss] = 309 L, elimination half-life [t1/2] = 86.3 h) and bone marrow (CL =1.68 L/h, Vss = 233 L, t1/2 = 98.8 h) were statistically different from each other and from reference values (CL = 4.50 L/h, Vss = 460 L, t1/2 = 71.0 h) published in the literature. SPECT/CT blood images were used as a surrogate of plasma concentrations to develop a population pharmacokinetic model. Weight was identified as covariate on volume of the central compartment, reducing the interindividual variability of all population pharmacokinetic parameters. CONCLUSION: This study is a proof of concept that obtaining pharmacokinetic parameters with image-based blood concentration is possible. Obtaining observed concentrations from SPECT/CT images, without the need for blood sampling, is a real advantage for the patient and the drug monitoring. Pharmacokinetic modeling could be combined with a deep learning model for automatic contouring and allow precise patient-specific dose adjustment in a non-invasive manner.

Identification of 18F-FDG PET/CT Parameters Associated with Weight Loss in Patients with Esophageal Cancer.

18F-FDG PET-CT is routinely performed as part of the initial staging of numerous cancers. Other than having descriptive, predictive and prognostic values for tumors, 18F-FDG PET-CT provides full-body data, which could inform on concurrent pathophysiological processes such as malnutrition. To test this hypothesis, we measured the 18F-FDG uptake in several organs and evaluated their association with weight loss in patients at diagnosis of esophageal cancer. Forty-eight patients were included in this retrospective monocentric study. 18F-FDG uptake quantification was performed in the brain, the liver, the spleen, bone marrow, muscle and the esophageal tumor itself and was compared between patients with different amounts of weight loss. We found that Total Lesion Glycolysis (TLG) and peak Standardized Uptake Values (SUVpeak) measured in the brain correlated with the amount of weight loss: TLG was, on average, higher in patients who had lost more than 5% of their usual weight, whereas brain SUVpeak were, on average, lower in patients who had lost more than 10% of their weight. Higher TLG and lower brain SUVpeak were associated with worse OS in the univariate analysis. This study reports a new and significant association between 18F-FDG uptake in the brain and initial weight loss in patients with esophageal cancer.

Tailored Media-Fill Test Protocols Inspired by 68Ga Kit-Based Radiopharmaceuticals.

Gallium-68 radiolabeling is an increasingly common activity in radiopharmacy. Single vial cold kits to radiolabel DOTATOC and PSMA-11 with 68Ga were developed, either for manual or automated preparation. Both approaches are very specific and require aseptic compounding skills, raising the need for dedicated training. The aim of this work was to design and implement an integrative media-fill test (MFT) protocol inspired by 68Ga kit-based radiopharmaceuticals for operator qualification, suitable for both manual and automated preparation simulations. Three custom MFT protocols (two manual and one automated simulations) compatible with specific radiopharmacy equipment were designed for operator training. During MFT sessions, the microbiological quality of the working environment was monitored by surface and air sampling. The sensitivity of the tryptic soy broth (TSB) and the influence of the number of punctures performed in each vial on the units positivity were also studied. Four operators were evaluated and carried out in triplicate the three MFTs. None of the 336 incubated units showed turbidity, although 27.8% of surface samples and 11.1% of air samples were positive (1-4 CFU). Over 36 MFT sessions, 15 contaminations of the working area by TSB drops occurred. TSB sensitivity was estimated >3.12 UFC. Units positivity showed a probable relationship with the number of punctures in a vial and, more obviously, with the contamination level of the vial stopper. As a part of a general sterile compounding instruction, these MFT protocols may be useful tools for initial and continuing training of operators carrying out manual and automated 68Ga radiolabeling.

177Lu-Dotatate administration using an infusion pump or a peristaltic pump: comparison of two methods.

OBJECTIVES: 177Lu-oxodotreotide (Lutathera) is an intravenous peptide receptor radionuclide therapy to treat unresectable metastatic digestive neuroendocrine tumours. The recommended method for Lutathera administration is gravity infusion; however, other appropriate and safe techniques are possible. This work compares two infusion methods from a medico-economic, radiation protection, efficiency and practicality point of view. METHODS: Two infusion methods were studied, either involving a volumetric infusion pump (method 1) or a peristaltic pump (method 2). For each method, the mean residual activity per vial and the mean injection time were compared. Occupational radiation exposure was measured. The cost of initial equipment and consumables for one administration was determined. Feedback from operators and past incidents during injections were collected through a survey. RESULTS: Three operators performed 219 Lutathera injections over 70 months: 60.7% (133) with method 1 and 39.3% (86) with method 2. After infusion, the mean residual activity in vial was 124.3±16.9 MBq with method 1 and 80.9±19.3 MBq with method 2 (34.9% decrease). The average administration time was 41±7.2 min with method 1 and 39±8.5 min with method 2. Occupational exposures obtained with both methods were very low and quite similar. Method 1 required an initial investment of 1165.8 US$ plus 4.0 US$ of supplies for each administration. Initial investment for method 2 was comparable (1261.4 US$) but supplies cost per administration was higher (12.5 US$). Two major incidents were recorded with method 1 and none with method 2. From operators' experience, method 2 felt safer and more suitable. CONCLUSIONS: Method 2 appeared to be convenient and secure, despite a higher cost per injection. It could also be applied to new radioligand therapies such as 177Lu-PSMA or 225Ac-Dotatate.

Development and Implementation of a Professional Practices Evaluation during Radiopharmaceuticals Administration.

Securing both the patient and radiopharmaceuticals (RPs) circuit is an essential concern in nuclear medicine (NM). These circuits converge at the RP administration phase, a key step in patient management in NM. In a continuous quality improvement approach, we developed and implemented an evaluation of professional practices (EPPs) methodology focused on RPs injection to identify and correct deviations from good practices. The nuclear medicine technologists (NMTs) of a single center were evaluated. A specific audit grid was designed for this purpose, covering 4 main themes. Following the audit campaign, an improvement action plan was set up to address the non-conformities observed. Nine NMTs were audited on 4 RPs injections each. The mean total score was 93.36% with, on average, 7.01% and 3.00% of unmet and partially met criteria, respectively. In view of the non-compliance rates of hygiene and radiation protection items, theoretical reviews of these themes were included in the improvement action plan. As a part of the quality assurance system of a healthcare unit, EPPs are useful for identifying and correcting practice deviations at an early stage. They should be regularly repeated and combined with rigorous training and qualification of operators involved in RPs injection.

Assessment of the Stratos, a new pencil-beam bone densitometer: dosimetry, precision, and cross calibration.

The goal of this study was to assess a new pencil-beam densitometer, the Stratos (Diagnostic Medical Systems, Pérols, France). Evaluation of the dosimetry and precision were done together with an in vivo cross-calibration study performed with the fan beam densitometer Discovery A (Hologic, Bedford, MA). The results indicated that the Stratos performed bone mineral density (BMD) measurements with a good precision, low radiation dose, and good agreement with the Discovery A. The air dose, measured by an ionization chamber, was 40 µGy. The effective dose was assessed using an anthropomorphic phantom and thermoluminescent detectors resulting in 1.96 and 0.31 µSv for a lumbar spine and proximal femur scan, respectively. The average scattered dose rate at a distance of 1m from the device was 1.06 and 1.21 µSv.h(-1) in the lumbar spine and left proximal femur scan mode, respectively. For the precision evaluation, 30 patients underwent 2 lumbar spine and 2 proximal femur scans with repositioning after each scan. The percentage root-mean-square coefficient of variation was 1.22%, 1.38%, 2.11%, and 0.86% for the lumbar spine (L1-L4), lumbar spine (L2-L4), femoral neck, and total hip, respectively. The cross-calibration studies were done on 57 patients (60 ± 9 yr). Lumbar spine, left neck, and left total hip mean BMD were 3.10% lower and 11.94% and 8.83% higher, respectively, with the Stratos compared with the Discovery A. Cross-calibration equations were calculated with a correlation coefficient of 98% (p<0.01) for the lumbar spine (L2-L4), 94% (p<0.01) for the left neck, and 92% (p<0.01) for the left total hip. After standardizing the Stratos measures using the cross-calibration equations, LIN's concordance correlation coefficient was 0.98, 0.93, and 0.92 for the lumbar spine (L2-L4), left neck, and total hip, respectively.

Brain FDG-PET changes in ALS and ALS-FTD.

BACKGROUND: FDG-PET in ALS most typically demonstrates a primary (and sometimes also supplementary) motor cortex hypometabolism, often associated with more diffuse cortical hypometabolism involving mostly the dorsolateral prefrontal cortex, the medial and lateral premotor cortices, and the bilateral insular cortex involvement. In ALS-FTD, extensive temporal hypometabolism is seen in addition to severe diffuse frontal hypometabolism. METHODS: This study analyses FDG-PET findings in 6 ALS patients and 4 ALS-FTD patients. RESULTS: In addition to earlier described areas of hypometabolism in ALS, we found also reduced FDG-PET metabolism in the medial frontal cortex, the orbitofrontal cortex, and the anterior temporal lobe in our ALS patients. The anterolateral area was the best preserved part of the frontal lobe in ALS patients. In ALS-FTD, frontal and temporal hypometabolism was severe (and parietal hypometabolism was often also present) with relatively preserved perirolandic metabolism. CONCLUSION: In ALS, more diffuse frontal and temporal FDG-PET hypometabolism was seen than earlier reported, with the anterolateral area as the best preserved part of the frontal lobe. In ALS-FTD, relatively preserved perirolandic metabolism was seen, associated with severe frontal and temporal hypometabolism.

Implementation and validation of an in-house combined fluorescein/media-fill test to qualify radiopharmacy operators.

BACKGROUND: The purpose of this work was to design, validate and implement a media-fill test combined with fluorescein (MFT-F) for the specific qualification and training of radiopharmacy operators, in accordance with United States Pharmacopeia General Chapter 797 and European Good Manufacturing Practices. MFT-F was embedded in the quality management system of our radiopharmacy unit. Its validation involved fluorescein concentration choice, media growth promotion test and evaluation protocol controls (with or without intentional aseptic mistakes). Each operator was evaluated following a three-part evaluation form. Evaluation criteria related to garbing and hygiene, fluorescent contamination and bacteriological contamination (pre- and post-evaluation environment controls and MFT-F samples). Combined MFT-F allowed the assessment of aseptic compounding skills and non-contamination of the working area through a single evaluation. It was also designed to fit the constraints of radiopharmacy common practice related to radiation protection equipment and to the small volumes handled. RESULTS: A 0.01% fluorescein concentration was chosen to prepare MFT-F. Addition of fluorescein in the culture medium did not jeopardize its growth properties according to growth promotion test. Eleven operators were evaluated and carried out 3 MFT-F over 3 successive days. Pre- and post-evaluation bacteriological controls of every session showed no CFU of microbiological contaminant above 5. All operators validated the garbing and hygiene evaluation, with an average score of 92.7%. All operators validated the fluorescent contamination evaluation, with an average score of 29.4 out of 30. None of the MFT-F samples showed any visible bacterial growth after incubation. CONCLUSIONS: Combined MFT-F, as a part of a comprehensive sterile compounding training program, appeared as a convenient and promising tool to increase both the sterile compounding safety and awareness of radioactive contamination in radiopharmacy.

Comparison of commercial dosimetric software platforms in patients treated with 177 Lu-DOTATATE for peptide receptor radionuclide therapy.

PURPOSE: The aim of this study was to quantitatively compare five commercial dosimetric software platforms based on the analysis of clinical datasets of patients who benefited from peptide receptor radionuclide therapy (PRRT) with 177 Lu-DOTATATE (LUTATHERA® ). METHODS: The dosimetric analysis was performed on two patients during two cycles of PRRT with 177 Lu. Single photon emission computed tomography/computed tomography images were acquired at 4, 24, 72, and 192 h post injection. Reconstructed images were generated using Dosimetry Toolkit® (DTK) from Xeleris™ and HybridRecon-Oncology version_1.3_Dicom (HROD) from HERMES. Reconstructed images using DTK were analyzed using the same software to calculate time-integrated activity coefficients (TIAC), and mean absorbed doses were estimated using OLINDA/EXM V1.0 with mass correction. Reconstructed images from HROD were uploaded into PLANET® OncoDose from DOSIsoft, STRATOS from Phillips, Hybrid Dosimetry Module™ from HERMES, and SurePlan™ MRT from MIM. Organ masses, TIACs, and mean absorbed doses were calculated from each application using their recommendations. RESULTS: The majority of organ mass estimates varied by <9.5% between all platforms. The highest variability for TIAC results between platforms was seen for the kidneys (28.2%) for the two patients and the two treatment cycles. Relative standard deviations in mean absorbed doses were slightly higher compared with those observed for TIAC, but remained of the same order of magnitude between all platforms. CONCLUSIONS: When applying a similar processing approach, results obtained were of the same order of magnitude regardless of the platforms used. However, the comparison of the performances of currently available platforms is still difficult as they do not all address the same parts of the dosimetric analysis workflow. In addition, the way in which data are handled in each part of the chain from data acquisition to absorbed doses may be different, which complicates the comparison exercise. Therefore, the dissemination of commercial solutions for absorbed dose calculation calls for the development of tools and standards allowing for the comparison of the performances between dosimetric software platforms.

Data acquisition analysis for femoral morphometric X-ray absorptiometry.

Bone mineral density (BMD) is a contributing factor of hip fracture risk. Other factors, such as lifestyle, the propensity for falls, and femoral geometry may influence the risk of hip fracture. The DMS Lexxos densitometer, a dual-energy X-ray densitometer can produce either a single-energy X-ray or a BMD image. The purpose of this study was to evaluate which of these 2 images enables the best detection to make femoral morphometry measurements. Spatial resolution, contrast, and noise were evaluated separately. A contrast-detail phantom was also used for the purpose of overall visual analysis. The spatial resolution was the same in the 2 images. The contrast was better with the BMD image, but the noise was higher. Using the contrast-detail phantom, the single-energy X-ray image allowed globally a better detection of the objects, but results were in the same range with high contrast values. Hip volunteers' morphometric measurements and the Singh Index were evaluated 3 times for each image by 3 observers, and the intra-, inter-, and global reproducibility was computed. The reproducibility of the measurements seems to be better with the single-energy X-ray image but results were not statistically significantly different. These results suggest that even if the image-quality indices were different, the single-energy X-ray image and BMD image are closely useful for clinical morphometric femoral evaluation.

Artificial nutrition in patients with cancer has no impact on tumour glucose metabolism: Results of the PETANC Study.

BACKGROUND & AIMS: Nutrition support is recommended in cachexic patients with cancer. However, there is no clear evidence about its impact on tumour growth. Glycolysis, which is usually higher in cancer than normal cells, can be monitored by 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) imaging that is widely used for cancer staging and therapy efficacy assessment. Here, we used 18F-FDG PET/CT imaging to investigate whether artificial nutrition has an impact on tumour glucose metabolism in patients with cancer and cachexia. METHODS: This prospective study included ten patients with histologically proven head and neck or oesophageal cancer. All patients underwent 18F-FDG PET/CT imaging at baseline and after (parenteral and/or enteral) nutrition support on average for 7 days. Tumour glucose metabolism changes were evaluated using static (SUVmax, SUVmean and SULpeak) and dynamic (glucose metabolic rate and transport constant rates, k) parameters computed from the 18F-FDG PET/CT data. RESULTS: Artificial nutrition (median energy intake of 21.83 kcal/kg/day [13.16-45.90], protein intake of 0.84 g/kg/day [0.56-1.64]) was administered. Eight patients (80%) received enteral nutrition and two patients (20%) parenteral support. Comparison of 18F-FDG PET/CT parameters did not highlight any significant difference in tumour glucose metabolism before and after the period of nutrition support. CONCLUSIONS: In cachexic patients with head and neck or oesophageal cancer, nutrition support administered according to the current guidelines shows no impact on tumour glucose metabolism, assessed by 18F-FDG PET/CT.

Cell membrane is a more sensitive target than cytoplasm to dense ionization produced by auger electrons.

To improve radioimmunotherapy with Auger electron emitters, we assessed whether the biological efficiency of (125)I varied according to its localization. A-431 and SK-OV-3 carcinoma cells were incubated with increasing activities (0-4 MBq/ml) of (125)I-labeled vectors targeting the cell membrane, the cytoplasm or the nucleus. We then measured cell survival by clonogenic assay and the mean radiation dose to the nucleus by assessing the cellular medical internal radiation dose (MIRD). The relationship between survival and the radiation dose delivered was investigated with a linear mixed regression model. For each cell line, we obtained dose-response curves for the three targets and the reference values (i.e., the dose leading to 75, 50 or 37% survival). When cell survival was expressed as a function of the total cumulative decays, nuclear (125)I disintegrations were more harmful than disintegrations in the cytoplasm or at the cell membrane. However, when survival was expressed as a function of the mean radiation dose to the nucleus, toxicity was significantly higher when (125)I was targeted to the cell membrane than to the cytoplasm. These findings indicate that the membrane is a more sensitive target than the cytoplasm for the dense ionization produced by Auger electrons. Moreover, cell membrane targeting is as cytotoxic as nuclear targeting in SK-OV-3 cells. We suggest that targeting the membrane rather than the cytoplasm may contribute to the development of more efficient radioimmunotherapies based on Auger electron radiation, also because most of the available vectors are directed against cell surface antigens.

Implementation of patient dosimetry in the clinical practice after targeted radiotherapy using [177Lu-[DOTA0, Tyr3]-octreotate.

BACKGROUND: This study's aim was to develop our dosimetric methodology using a commercial workstation for the routine evaluation of the organs at risk during peptide receptor radionuclide therapy (PRRT) with 177Lu. METHODS: First, planar and SPECT sensitivity factors were determined on phantoms. The reconstruction parameters were optimized by SPECT/CT image acquisition using a NEMA IEC phantom containing a 500 ml bottle of 177Lu, to simulate a kidney. The recovery coefficients were determined on various phantoms. For the red marrow, this was calculated using a NEMA IEC phantom that contained a centrally placed bottle of 80 ml of 177Lu (to model the L2-L4 red marrow) flanked by two 200 ml bottles with 177Lu to simulate the kidneys. Then, SPECT/CT images were acquired at 4, 24, 72, and 192 h after injection in 12 patients with neuroendocrine tumors who underwent PRRT with 177Lu-DOTATATE. SPECT data were reconstructed using the iterative ordered subset expectation maximization (OSEM) method, with six iterations and ten subsets, attenuation, scatter, recovery resolution corrections, and a Gaussian post-filter of 0.11 cm. The liver, spleen, kidneys, and red marrow dose per administered activity (AD/A admin) values were calculated with the Medical Internal Radiation Dose (MIRD) formalism and the residence times (Dosimetry toolkit® application) using standard and CT imaging-based organ masses (OLINDA/EXM® V1.0 software). RESULTS: Sensitivity factors of 6.11 ± 0.01 and 5.67 ± 0.08 counts/s/MBq were obtained with planar and SPECT/CT acquisitions, respectively. A recovery coefficient of 0.78 was obtained for the modeled L2-L4 red marrow. The mean AD/A admin values were 0.43 ± 0.13 mGy/MBq [0.27-0.91] for kidneys, 0.54 ± 0.58 mGy/MBq [0.12-2.26] for liver, 0.61 ± 0.13 mGy/MBq [0.42-0.89] for spleen, and 0.04 ± 0.02 mGy/MBq [0.01-0.09] for red marrow. The AD/A admin values varied when calculated using the personalized and standard organ mass, particularly for kidneys (p = 1 × 10-7), spleen (p = 0.0069), and red marrow (p = 0.0027). Intra-patient differences were observed especially in organs close to or including tumor cells or metastases. CONCLUSIONS: The obtained AD/A admin values were in agreement with the literature data. This study shows the technical feasibility of patient dosimetry in clinical practice and the need to obtain patient-specific information.