Promising clinical performance of pretargeted immuno-PET with anti-CEA bispecific antibody and gallium-68-labelled IMP-288 peptide for imaging colorectal cancer metastases: a pilot study.

INTRODUCTION: This pilot study evaluated the imaging performance of pretargeted immunological positron emission tomography (immuno-PET) using an anti-carcinoembryonic antigen (CEA) recombinant bispecific monoclonal antibody (BsMAb), TF2 and the [68Ga]Ga-labelled HSG peptide, IMP288, in patients with metastatic colorectal carcinoma (CRC). PATIENTS AND METHODS: Patients requiring diagnostic workup of CRC metastases or in case of elevated CEA for surveillance were prospectively studied. They had to present with elevated CEA serum titre or positive CEA tumour staining by immunohistochemistry of a previous biopsy or surgical specimen. All patients underwent endoscopic ultrasound (EUS), chest-abdominal-pelvic computed tomography (CT), abdominal magnetic resonance imaging (MRI) and positron emission tomography using [18F]fluorodeoxyglucose (FDG-PET). For immuno-PET, patients received intravenously 120 nmol of TF2 followed 30 h later by 150 MBq of [68Ga]Ga-labelled IMP288, both I.V. The gold standard was histology and imaging after 6-month follow-up. RESULTS: Eleven patients were included. No adverse effects were reported after BsMAb and peptide injections. In a per-patient analysis, immuno-PET was positive in 9/11 patients. On a per-lesion analysis, 12 of 14 lesions were positive with immuno-PET. Median SUVmax, MTV and TLG were 7.65 [3.98-13.94, SD 3.37], 8.63 cm3 [1.98-46.64; SD 14.83] and 37.90 cm3 [8.07-127.5; SD 43.47] respectively for immuno-PET lesions. Based on a per-lesion analysis, the sensitivity, specificity, positive-predictive value and negative-predictive value were, respectively, 82%, 25%, 82% and 25% for the combination of EUS/CT/MRI; 76%, 67%, 87% and 33% for FDG-PET; and 88%, 100%, 100% and 67% for immuno-PET. Immuno-PET had an impact on management in 2 patients. CONCLUSION: This pilot study showed that pretargeted immuno-PET using anti-CEA/anti-IMP288 BsMAb and a [68Ga]Ga-labelled hapten was safe and feasible, with promising diagnostic performance. TRIAL REGISTRATION: ClinicalTrials.gov NCT02587247 Registered 27 October 2015.

GATE V6: a major enhancement of the GATE simulation platform enabling modelling of CT and radiotherapy.

GATE (Geant4 Application for Emission Tomography) is a Monte Carlo simulation platform developed by the OpenGATE collaboration since 2001 and first publicly released in 2004. Dedicated to the modelling of planar scintigraphy, single photon emission computed tomography (SPECT) and positron emission tomography (PET) acquisitions, this platform is widely used to assist PET and SPECT research. A recent extension of this platform, released by the OpenGATE collaboration as GATE V6, now also enables modelling of x-ray computed tomography and radiation therapy experiments. This paper presents an overview of the main additions and improvements implemented in GATE since the publication of the initial GATE paper (Jan et al 2004 Phys. Med. Biol. 49 4543-61). This includes new models available in GATE to simulate optical and hadronic processes, novelties in modelling tracer, organ or detector motion, new options for speeding up GATE simulations, examples illustrating the use of GATE V6 in radiotherapy applications and CT simulations, and preliminary results regarding the validation of GATE V6 for radiation therapy applications. Upon completion of extensive validation studies, GATE is expected to become a valuable tool for simulations involving both radiotherapy and imaging.

Preoperative localization of parathyroid lesions. Value of 99mTc-MIBI tomography and factors influencing detection.

UNLABELLED: The AIM of our study was to assess retrospectively the value of (99m)Tc-MIBI SPECT in the localization of parathyroid lesions in primary hyperparathyroidism and to determine the impact of PTH level, age, sex, characteristics of the lesions and thyroid nodules on the sensitivity of imaging. PATIENTS, METHODS: Fifty nine patients who were cured after the resection of 60 lesions (50 adenomas, 9 hyperplasias and 1 carcinoma, 9 of them in ectopy) were selected. (99m)TcO(4)(-), early and late (99m)Tc-MIBI planar images (n = 59), (99m)Tc-MIBI SPECT (n = 58) and ultrasound (n = 50) performed preoperatively were analyzed. The imaging results were compared to surgical and histological findings and correlated to different factors suspected of influencing the imaging's sensitivity. RESULTS: Sensitivity of double phase (99m)Tc-MIBI/(99m)TcO(4)(-) scintigraphy was higher than that of early or late scintigraphy alone. SPECT increased the sensitivity of scintigraphy from 85% to 92% and was useful to confirm doubtful foci and to localize ectopic lesions. Ultrasound (US) had the lowest sensitivity (56%) and the highest rate of false-positive results (n = 10), but identified 2 adenomas which were not detected by scintigraphy. Combining all imaging modalities, sensitivity reached 96%. Better sensitivities were observed when age <69 years, preoperative PTH level > or =155 pg/ml, weight of the gland > or =0.80 g and in the absence of thyroid nodules. US was more influenced by these factors than scintigraphy. CONCLUSION: Combination of US, double-phase (99m)Tc-MIBI/(99m)TcO(4)(-) planar scintigraphy and SPECT is the most accurate method for the detection of parathyroid lesions and should be performed before minimally invasive surgery, especially when PTH level is low, in older patients and in cases of multinodular goiter.

Comparison of positron emission tomography and lymphangiography in the diagnosis of infradiaphragmatic Hodgkin's disease.

PURPOSE: To evaluate the respective roles of positron emission tomography using 18F-fluorodeoxyglucose (FDG-PET) and lymphangiography (LAG) in staging Hodgkin's disease (HD) patients with negative contrast-enhanced infradiaphragmatic computed tomography (CT). MATERIAL AND METHODS: 28 patients underwent FDG-PET and LAG at initial staging. Concordant positive findings on both tests were regarded as actual HD locations and concordant negative findings as true negative. In case of discrepancy, the reference was biopsy or magnetic resonance imaging (MRI). RESULTS: Concordant results were obtained in 26 patients (24 negative, two positive). In two of the 24 negative patients, PET showed additional lesions in the spleen and one celiac lymph node (one patient), and in the right kidney and the right iliac crest (one patient). Discordant results were obtained in two patients. Both methods indicated infradiaphragmatic involvement in different locations in one patient. In the other, PET was falsely positive (PET done within 24 hours after a negative LAG), which was confirmed by biopsy (benign inflammatory, probably due to LAG medium). CONCLUSION: FDG-PET and LAG gave comparable results, making invasive LAG unnecessary. Furthermore, LAG, when performed before PET, can be responsible for false-positive PET results.