Céline Heimburger

18 F-DOPA PET/CT in the diagnosis and localization of persistent medullary thyroid carcinoma

PurposeTo evaluate the performance of 18F-l-dihydroxyphenylalanine (18F-DOPA) PET/CT in the detection of locoregional and distant medullary thyroid carcinoma (MTC) metastases and to compare imaging findings with histological data.MethodsWe retrospectively evaluated 86 MTC patients with persistently high serum calcitonin levels after initial surgery who had undergone 18F-DOPA PET/CT between January 2007 and December 2014 in two referral centres. They were followed up for at least 6xa0months after the PET/CT assessment. The results were compared with histological data or with the findings obtained during follow-up using a complementary imaging modality.Results18F-DOPA PET/CT was positive in 65 of the 86 patients, corresponding to a patient-based sensitivity of 75.6 %. Distant metastatic disease (M1) was seen in 29 patients including 11 with previously unknown metastases revealed only by PET/CT. Among the 36 patients without distant metastatic spread, 25 had nodal involvement limited to the neck, and 10 of these 25 patients underwent reoperation. The lymph node compartment-based sensitivity of 18F-DOPA PET/CT was 100 % in the two institutions but lesion-based sensitivity was only 24 %. Preoperative and postoperative median calcitonin levels were 405 pg/mL (range 128xa0–xa01,960 pg/mL) and 259 pg/mL (range 33xa0–xa01,516 pg/mL), respectively. None of the patients achieved normalization of serum calcitonin after reoperation.Conclusion18F-DOPA PET/CT enables early diagnosis of a significant number of patients with distant metastasis. It has a limited sensitivity in the detection of residual disease but provides high performance for regional analysis. A surgical compartment-oriented approach could be the approach of choice whatever the number of nodes revealed by 18F-DOPA PET/CT.

Metabolomics approaches in pancreatic adenocarcinoma: tumor metabolism profiling predicts clinical outcome of patients

BackgroundPancreatic adenocarcinomas (PAs) have very poor prognoses even when surgery is possible. Currently, there are no tissular biomarkers to predict long-term survival in patients with PA. The aims of this study were to (1) describe the metabolome of pancreatic parenchyma (PP) and PA, (2) determine the impact of neoadjuvant chemotherapy on PP and PA, and (3) find tissue metabolic biomarkers associated with long-term survivors, using metabolomics analysis.Methods1H high-resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy using intact tissues was applied to analyze metabolites in PP tissue samples (nu2009=u200917) and intact tumor samples (nu2009=u2009106), obtained from 106 patients undergoing surgical resection for PA.ResultsAn orthogonal partial least square-discriminant analysis (OPLS-DA) showed a clear distinction between PP and PA. Higher concentrations of myo-inositol and glycerol were shown in PP, whereas higher levels of glucose, ascorbate, ethanolamine, lactate, and taurine were revealed in PA. Among those metabolites, one of them was particularly obvious in the distinction between long-term and short-term survivors. A high ethanolamine level was associated with worse survival. The impact of neoadjuvant chemotherapy was higher on PA than on PP.ConclusionsThis study shows that HRMAS NMR spectroscopy using intact tissue provides important and solid information in the characterization of PA. Metabolomics profiling can also predict long-term survival: the assessment of ethanolamine concentration can be clinically relevant as a single metabolic biomarker. This information can be obtained in 20xa0min, during surgery, to distinguish long-term from short-term survival.

18F-FDG PET/CT for the Diagnosis of Malignant and Infectious Complications After Solid Organ Transplantation

PurposeInfection and malignancy represent two common complications after solid organ transplantation, which are often characterized by poorly specific clinical symptomatology. Herein, we have evaluated the role of 18F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) in this clinical setting.MethodsFifty-eight consecutive patients who underwent FDG PET/CT after kidney, lung or heart transplantation were included in this retrospective analysis. Twelve patients underwent FDG PET/CT to strengthen or confirm a diagnostic suspicion of malignancies. The remaining 46 patients presented with unexplained inflammatory syndrome, fever of unknown origin (FUO), CMV or EBV seroconversion during post-transplant follow-up without conclusive conventional imaging. FDG PET/CT results were compared to histology or to the finding obtained during a clinical/imaging follow-up period of at least 6 months after PET/CT study.ResultsPositive FDG PET/CT results were obtained in 18 (31xa0%) patients. In the remaining 40 (69xa0%) cases, FDG PET/CT was negative, showing exclusively a physiological radiotracer distribution. On the basis of a patient-based analysis, FDG PET/CT’s sensitivity, specificity, PPV and NPV were respectively 78xa0%, 90xa0%, 78xa0% and 90xa0%, with a global accuracy of 86xa0%. FDG PET/CT was true positive in 14 patients with bacterial pneumonias (nu2009=u20094), pulmonary fungal infection (nu2009=u20091), histoplasmosis (nu2009=u20091), cutaneous abscess (nu2009=u20091), inflammatory disorder (sacroiliitis) (nu2009=u20091), lymphoma (nu2009=u20093) and NSCLC (nu2009=u20093). On the other hand, FDG PET/CT failed to detect lung bronchoalveolar adenocarcinoma, septicemia, endocarditis and graft-versus-host disease (GVHD), respectively, in four patients. FDG PET/CT contributed to adjusting the patient therapeutic strategy in 40xa0% of cases.ConclusionsFDG PET/CT emerges as a valuable technique to manage complications in the post-transplantation period. FDG PET/CT should be considered in patients with severe unexplained inflammatory syndrome or FUO and inconclusive conventional imaging or to discriminate active from silent lesions previously detected by conventional imaging particularly when malignancy is suspected.

FDOPA PET-CT of Nonenhancing Brain Tumors.

Background Primary brain tumor grading is crucial to rapidly determine the therapeutic impact and prognosis of a brain tumor as well as the tumors’ aggressiveness profile. On magnetic resonance imaging, high-grade tumors are usually responsible for blood -brain barrier breakdowns, which result in tumor enhancement. However, this is not always the case. The main objective of this study was to evaluate the diagnostic value of FDOPA PET in the assessment of primary brain tumor aggressiveness with no contrast enhancement on MRI. Methods Fifty-three patients were prospectively included: 35 low-grade and 18 high-grade histologically proven gliomas, with no contrast enhancement. Each patient underwent static PET acquisitions at 30 minutes. All patients had MRSI with measurements of different metabolites ratio. Results FDOPA was useful in the subgroup of low-grade gliomas, discriminating between dysembryoplastic neuroepithelial tumor and grade II oligodendroglioma (P < 0.01). An optimal threshold of the maximum standardized uptake value at 30 minutes (SUVmax (T/N)30) = 2.16 to discriminated low- from high-grade gliomas with a sensitivity of 60%, specificity of 100%, PPV of 100%, and NPV of 83.33% (P < 0.01). The nCho/Cr and nCho/NAA ratios were significantly higher in high- than in low-grade gliomas (P < 0.03 and P < 0.04, respectively). A significant positive correlation between MRSI ratios and SUVmax was found. Conclusion Including data from amino acid metabolism used alone or in association with MRSI allows us to discriminate between dysembryoplastic neuroepithelial tumor and grade II oligodendroglioma and between low- and high-grade gliomas with no contrast enhancement on MRI.

Head-to-head comparison between (18)F-FDOPA PET/CT and MR/CT angiography in clinically recurrent head and neck paragangliomas.

PurposeHead and neck paragangliomas (HNPGLs) can relapse after primary treatment. Optimal imaging protocols have not yet been established for posttreatment evaluation. The aim of the present study was to assess the diagnostic value of 18F-FDOPA PET/CT and MR/CT angiography (MRA/CTA) in HNPGL patients with clinical relapse during their follow-up.MethodsSixteen consecutive patients presenting with local pain, tinnitus, dysphagia, hoarse voice, cranial nerve involvement, deafness, or retrotympanic mass appearing during follow-up after the initial treatment of HNPGLs were retrospectively evaluated. Patients underwent both 18F-FDOPA PET/CT and MRA (15 patents) or CTA (1 patent). Both methods were first assessed under blinded conditions and afterwards correlated. Head and neck imaging abnormalities without histological confirmation were considered true-positive results based on a consensus between radiologists and nuclear physicians and on further 18F-FDOPA PET/CT and/or MRA.Results18F-FDOPA PET/CT and MRA/CTA were concordant in 14 patients and in disagreement in 2 patients. 18F-FDOPA PET/CT and MRA/CTA identified, respectively, 12 and 10 presumed recurrent HNPGLs in 12 patients. The two lesions diagnosed by PET/CT only were confirmed during follow-up by otoscopic examination and MRA performed 29 and 17xa0months later. 18F-FDOPA PET/CT images were only slightly influenced by the posttreatment sequelae, showing a better interobserver reproducibility than MRA/CTA. Finally, in 2 of the 16 studied patients, 18F-FDOPA PET/CT detected two additional synchronous primary HNPGLs.Conclusion18F-FDOPA PET/CT is highly sensitive in posttreatment evaluation of patients with HNPGLs, and also offers better interobserver reproducibility than MRA/CTA and whole-body examination. We therefore suggest that 18F-FDOPA PET/CT is performed as the first diagnostic imaging modality in symptomatic patients with suspicion of HNPGL relapse after primary treatment when 68Ga-labeled somatostatin analogues are not available.

Small Bowel Carcinoid: The "Dancing Bowel Sign" on 18F-FDOPA PET/CT.

The localization of small bowel (SB) neuroendocrine tumors (NETs) remains a diagnostic challenge in clinical practice. In about a third of cases, SB-NETs are multiple at diagnosis. However, the sensitivity of conventional presurgical diagnostic investigations is not exhaustive. F-FDOPA (6-L-F-fluorodihydroxyphenylalanine) PET seems to be a valuable diagnostic technique for the detection of midgut NETs. According to our experience, a delayed PET/CT acquisition centered on abdominopelvic region and performed after oral hydration may improve the detection of primary tumor and the identification of patients with multifocal SB-NETs who could benefit from a more accurate intraoperative palpation of the entire SB.

Carbidopa-assisted 18 F-fluorodihydroxyphenylalanine PET/CT for the localization and staging of non-functioning neuroendocrine pancreatic tumors

ObjectiveCD premedication was found to increase the value of 18F-fluorodihydroxyphenylalanine (18F-FDOPA) PET/CT imaging in the detection of adult insulinoma. The aim of this study was to evaluate the performance of CD-assisted 18F-FDOPA PET/CT in the diagnosis and staging of non-functioning pNETs.MethodsTwenty consecutive patients with low-grade pNETs who underwent CD-assisted 18F-FDOPA PET/CT imaging and 111In-somatostatin receptor scintigraphy (SRS) were evaluated. Histology was considered as the gold standard. In case where no surgical resection was performed, the diagnosis of pNET was made by the confrontation of the different available imaging modalities.ResultsCD-assisted 18F-FDOPA PET/CT was positive in 18/20 cases (90xa0%), whereas SRS was positive in 13/19 cases (68xa0%). When considered the 19 patients underwent both nuclear medicine examinations, 18F-FDOPA PET/CT was significantly more sensitive then SRS for primary tumor detection (pxa0=xa00.049). False-negative results of both 18F-FDOPA PET/CT and SRS were observed in 2 cystic pNETs. SRS failed to detect one additional cystic tumor and 3 pNETs of 10, 12 and 17xa0mm, respectively. 18F-FDOPA PET/CT correctly identified all patients with lymphatic, visceral and bone metastases. SRS failed to detect lymphatic spread and was falsely negative in one patient with splenic metastasis.ConclusionsContrary to widely held assumptions, our study further expands the application of CD-assisted 18F-FDOPA PET/CT for non-functioning pNETs when 68Ga-radiolabeled somatostatin analogs are not available.

Positional Brain Single-Photon Emission Computed Tomography Findings in a Case of Limb-Shaking Syndrome

An 84-year-old man, who presented lower limbs limb-shaking syndrome at orthostatism lasting a few seconds, was referred in our stroke unit. Magnetic resonance imaging showed an acute infarction in the right thalamus and the insular cortex, left extracranial carotid stenosis at 80%, and low flow in the right middle cerebral artery but did not explain limb-shaking syndrome symptomatology. We performed comparative positional brain perfusion single-photon emission computed tomography (SPECT), in the upright and in the supine position, to explore and localize hypoperfusion-endangered brain structures that may be involved in the presenting symptoms. Brain perfusion SPECT showed deep hypoperfusion in bilateral carotid territories in the upright position in favor of a hemodynamic mechanism, on which blood pressure was maintained higher to avoid hypoperfusion and the patient remained supine for a longer period of time than in the usual support. Late postoperative brain perfusion SPECT after left endarterectomy did not show significant abnormalities. Limb-shaking syndrome may be related to a transient decrease in blood pressure and cerebral blood flow caused by postural changes. Positional brain perfusion SPECT seems to be helpful to improve clinical care. Positional brain perfusion SPECT should be discussed in the acute phase of stroke and if there are involuntary movements.

Adrenal Metastasis of a Poorly Differentiated Adenocarcinoma Mimicking a Pheochromocytoma on 18F-FDOPA PET/CT.

We report the surprising intense uptake of F-FDOPA in a right adrenal metastasis of a poorly differentiated metastatic adenocarcinoma of unknown primary mimicking a pheochromocytoma in a hemodialyzed patient with the typical Menards triad and increased serum catecholamines. Our observation emphasizes that F-FDOPA is not a specific radiotracer for pheochromocytoma and paraganglioma investigation, although it is currently and successfully used in this clinical setting. Moreover, we underline that kidney failure may be responsible for abnormally high serum catecholamines values even in subjects without pheochromocytoma, leading to erroneous diagnostic conclusions particularly in patients with adrenal masses.

FDG PET in Intracranial Carcinomatous Meningitis.

A 63-year-old white man, diagnosed with pT3N2 squamous cell lung carcinoma, underwent right upper lobectomy with adjuvant radiochemotherapy. After a partial epileptic seizure, MRI revealed a solitary right frontal metastasis that was treated with surgical resection followed by stereotaxic radiotherapy. Three months later, the patient presented weight loss, weakness, and headache. He underwent a whole-body FDG PET/CT for restaging. It showed intense FDG uptakes on the brain periphery corresponding to nodular meningeal contrast enhancement on MRI leading to the diagnosis of carcinomatous meningitis, despite negative cerebrospinal fluid cytology.