Apports de l’acquisition TDM couplée à la scintigraphie pulmonaire dans l’exploration d’une suspicion d’embolie pulmonaire

Pulmonary embolism is a frequent disease difficult to diagnose because of heterogeneous clinical presentation. Pulmonary embolism diagnosis requires additional examinations, which are guided by clinical probability scores. The ventilation/perfusion scintigraphy is a validated technic in pulmonary embolism diagnosis strategies, which represents one of its most important indications. In the past years, the technique of scintigraphy evolved with the appearance of hybrid cameras, allowing the realization of tomoscintigraphy coupled with computerised tomodensitometry (CT). One of the major interests of this technique is the possibility of considering alternative diagnosis in case of negative result of scintigraphy. The purpose of this article is to offer nuclear medicine physicians a review of the alternative diagnoses that can be found during pulmonary ventilation/perfusion tomoscintigraphy according to the underlying scintigraphic and morphological abnormalities. In this review, we will first on diseases responsible for: a mismatch (pathological perfusion and normal ventilation), an inverted mismatch (normal perfusion and pathological ventilation) and for associated disorders in ventilation and in perfusion patterns (identically abnormal perfusion and ventilation). The final part will address some specific CT features that can be encountered on a low dose CT centered on thorax.     

Application de l’imagerie moléculaire par fluorescence à la clinique

Fluorescence probes and imaging methods have been extensively developed in microscopy to visualize biological pathways, cell trafficking and intracellular interactions, which are the main targets of molecular imaging. The translation of these methods from microscopy to preclinical and clinical applications requires to image through large thickness of live biological tissues, and to ensure the non-toxicity of the probes. We hereafter list the main issues that must be addressed to translate fluorescence techniques to clinic, and we present the main envisioned solutions. As first realistic clinical application, we present work in progress on intraoperative fluorescence guided surgery.     

Apport de la TEP/TDM au 18FDG dans le bilan préopératoire des phéochromocytomes. Étude rétrospective comparative par rapport à la scintigraphie à la MIBG

Pheochromocytomas (PHEO) are tumors arisen from the adrenal medulla, with a high secretory risk. Malignancy is rare and difficult to establish before metastastic spread. The risk of multifocality becomes greater whether genetic predisposition exists. MIBG scintigraphy is the reference functional imaging of PHEO. The place of 18FDG PET/CT is not well-established in literature. Our study retrospectively analyzes patients operated for a PHEO and who underwent both MIBG and 18FDG PET/CT before surgery, between 2007 and 2015. On the 49 patients included (52 lesions), among them 13 had genetic mutation, MIBG detected 39 lesions (75%) and 18FDG PET/CT forty-eight (92%), enabling a combined sensitivity of 98%. Sensitivity was not affected by the predominant secretion (metanephrine or normetanephrine), whereas MIBG-negative lesions showed a higher proliferation index (Ki67) than MIBG-positive lesions (6.6 vs. 2.8; P = 0.0044). FDG PET/CT semi-quantitative indices vary with the germline mutation status and were significantly higher for Cluster 1 lesions (SDHx, VHL or FH mutations) than for any other lesions (SUVmax = 27.73 vs. 5.92 for the others mutations (Cluster 2), 9.53 for lesions without mutation and 3.78 for undetermined lesions; P = 0.002). In conclusion, because of their capacity to take up FDG, 18FDG PET/CT could be useful in the preoperative imaging of PHEO, especially when MIBG is not contributive or when F-DOPA PET/CT is not available. An intense FDG uptake may orient to a Cluster 1 mutation.     

Optimisation du protocole d’acquisition de la TEP à la fluorocholine dans la détection des lésions parathyroïdiennes

18F-Fluorocholine (FCH) PET/CT shows very promising potential for detection of hyperfunctioning parathyroid tumors. However, the optimal time to perform imaging after FCH administration has not yet been determined and protocols are highly variable. The aim of this study was to qualitatively and quantitatively compare 5, 10, 15, 20 and 60 min post-injection acquisition times in patients with primary hyperparathyroidism and equivocal traditional imaging. Thirty-one patients were included. Two observers retrospectively analyzed the five protocols. Any focal increase in FCH uptake was localized and graded on a discrete gradation scale between 1 and 5 to assess the likelihood of hyperfunctioning parathyroid tumors. Gold standard was histopathological findings for the 11 operated patients. Regarding quantitative analysis, ratio of SUVmax of parathyroid foci on SUVmean of thyroid background (as signal-to-noise ratio) were compared between protocols. After injection of 2.5 MBq/kg, FCH PET performed 60 min post-injection (2 min) had the best sensitivity and specificity by lesion (92% and 100% respectively and the best signal-to-noise ratio (median of 2). We suggest performing PET scan 60 min after injection, associated with early acquisition so as not to miss a wash-out hyperfunctioning parathyroid tumors.     

Variation de la captation hépatique de 18-FDG dans l’évaluation intermédiaire des lymphomes B diffus à grandes cellules en TEP/TDM

IntroductionThe aim of this study was to evaluate the variability of 18F-FDG liver uptake at interim PET/CT among patients with high-grade lymphomas.MethodsForty-six patients with diffuse large B-cell lymphomas (DLBCL) who underwent 18F-FDG PET/CT at baseline (PET1) and after a few cycles of therapy (PET2) were included retrospectively. SUV mean normalized for body weight (SUVmean) and for lean body mass (SULmean) were obtained from 2-dimensional regions of interest (ROI) in the right lobe of the liver.ResultsLiver SUVmean values for the 46 patients were not different before and after the courses of chemotherapy. On univariate and multivariate analysis, liver SUVmean values increased with BMI (P = 0.0031). No significant correlation was found between delay post-injection, blood glucose level, age, gender and liver SUVmean. We found no statistically significant correlation between the liver SULmean or mediastinum SUVmean and studied variables. No factors affecting intrapatient hepatic uptake variation between PET1 and PET2 were found on correlation analysis.ConclusionAt interim PET in diffuse large B-cell lymphomas, liver SUVmean depends on BMI, but not liver SULmean. Caution is required when using liver SUV as reference in patients with high BMI.     

Contribution à la connaissance des Copépodes de la Région Parisienne

Sans résumé     

Évaluation de la faisabilité de la tomoscintigraphie myocardique précoce au sestamibi synchronisée à l’électrocardiogramme

BackgroundOur aim was to assess the feasibility of early acquisition (10 min) gated single photon emission computed tomography (SPECT) by comparison to conventional imaging at one hour.Methods and resultsOne hundred and four patients referred for exercise test and SPECT were included. Sequential imaging was started 10 min (SPECT 10) and 60 min (SPECT 60) after injection of the radiotracer (Tc-99m sestamibi). Stress myocardial perfusion was visually analyzed from 10 to 60 min stress by two experienced nuclear-cardiologists. Six patients were further excluded, because of high digestive accumulation: one patient at 10 min, three at 10 and 60 min, two at rest. The participants were classified as follows: group G1 (normal SPECT 10 and 60, n = 53), group G2 (abnormal SPECT 10 and/or SPECT 60, n = 45). The left ventricle ejection fraction (EF) and volumes (end-systolic and end-diastolic volumes, ESV, EDV) were calculated with the Cedars-Sinai program.ResultsQuality imaging was the same at SPECT 10 min and SPECT 60 min. Perfusion scores: G1 10 min = 0,4 versus G1 60 min = 0,4 (p = NS); G2 10 min = 10,2 versus G2 60 min = 10,1 (p = NS); EFG1 10 min = 71 ± 11% versus EFG1 60 min = 68 ± 10% (p = 4E-04); EFG2 10 min = 56 ± 15% versus EFG2 60 min = 53 ± 15% (p = 0,002); EDV G1 10 min = 72 ± 20 ml versus EDV G1 60 min = 76 ± 19 (p = 0,002); EDV G2 10 min = 98 ± 46 ml versus EDV G2 60 min = 105 ± 38 (p = 0,08); ESVG1 10 min = 22 ± 12 m versus ESV G1 60 min = 25 ± 12 (p = 9E-04); ESVG2 10 min = 47 ± 35 ml versus ESV G2 60 min = 53 ± 36 (p = 3E-04).ConclusionsThis study suggests that early gated Sestamibi SPECT after stress provides same perfusion analysis than classical late imaging.     

Évaluation de la tomoscintigraphie de perfusion pulmonaire couplée à la tomodensitométrie dans la prédiction de la fonction respiratoire postopératoire

IntroductionThe aim of our study was to evaluate the performances of pulmonary perfusion single photon emission computed tomography-computed tomography (SPECT-CT) with semi-automatic analysis for preoperative assessment for lung cancer.Materiel and methodThirty-five patients underwent preoperative lung perfusion scintigraphy (planar and SPECT-CT acquisition) from august 2016 to December 2017. Predicted postoperative forced expiratory volume in one second (ppoFEV1 and FEV1) by both methods were compared between each other and with the actual FEV1 measured 3 months after surgery. We also evaluated interobserver reproductibility of SPECT-CT semi-automatic segmentation software and the concordance of the data simulating reductions of 30 and 50% of acquisition time.ResultsFor 30 lobectomies and 5 pneumonectomies, the mean ppoFEV1 was 69%, a difference with actual ppoFEV1 of ?8% for SPECT-CT and ?6.77% for planar (P < 0,001). Both methods were well correlated, correlation coefficient was 0,827, 95% CI [0.686–0.909] but underestimated the actual poppFEV1. For SPECT-CT, interobserver reproducibility was excellent for pulmonary and lobar evaluation. The lobar functions, without 30 and 50% of the time acquisition, had absolute difference < 3% in comparison to native data.DiscussionWe did not prove SPECT-CT superiority on planar scintigraphy, actual FEV1 being difficult to predict because of confounding factors. But this exam could be useful before lobectomy and in cases of heterogeneous perfusion. Easily made, this method is reproducible even on data simulating a reduction of 50% of time acquisition.     

Efficacité comparée de l'antibioprophylaxie par la céfoxitine en une ou trois doses dans la césarienne.

To compare the effectiveness of three doses and of a single dose of cefoxitin, a second-generation cephalosporin, in preventing infection after nonelective cesarean section, we carried out a prospective study in 255 women who underwent the procedure between March 1983 and February 1985. The rate of postoperative infection was 7% in the group that received three doses and 8% in the one-dose group. The sensitivity and specificity of perioperative cultures were low. The rate of asymptomatic bacteriuria was high, at 20%, but few symptomatic urinary tract infections were found. Routine antibiotic prophylaxis with a single dose is suggested for all nonelective cesarean sections.     

Impact de la TEP/TDM au 18F-FDG dans la prise en charge des patients atteints de cancer thyroïdien différencié

Aim¹⁸F-FDG PET/CT by combining both metabolic and anatomical informations has proven to be an effective modality for detecting many types of cancer. Some differentiated forms of cancer like differentiated thyroid carcinoma (DTC) are less FDG avid and thus less easily detectable. Nevertheless ¹⁸F-FDG PET/CT has been proved useful in DTC especially in case of suspected recurrent disease with negative whole-body radioiodine scintigraphy (¹³¹I WBS) and elevated thyroglobulin (Tg) or thyroglobulin autoantibodies (AbTg) levels. Impact on clinical management after ¹⁸F-FDG PET/CT examinations has been analyzed in patients with suspected recurrent DTC in this retrospective study.MethodologyFifty-five ¹⁸F-FDG PET/CT were performed in 45 patients with suspected recurrent or residual disease either because of elevated Tg/AbTg levels (n = 45) or uncertain conventional imaging (n = 10) including ¹³¹I WBS, cervical echography and CT scan if necessary. ¹⁸F-FDG PET/CT results were compared with histopatology and/or clinical follow-up with evaluation of impact on clinical management.ResultsTwenty-nine exams were positive (53 %). There were 20 true-positive (TP) (14 locoregional relapses and six with distant metastases) and nine false-positive (FP) (all cervical). SUV_max median values of hypermetabolic foci were significantly higher in TP (5.1) than in FP (2.8). Overall, 20 (36 %) ¹⁸F-FDG PET/CT directly affected clinical management resulting in 13 (65 %) new surgical operations. Sensitivity, specificity, predictive positive value, predictive negative value and accuracy of ¹⁸F-FDG PET/CT were estimated for the whole group (respectively 83 %, 71 %, 69 %, 85 % and 76 %) and for two subgroups depending on Tg level (less or more than 1.2 ng/mL).Discussion and conclusion¹⁸F-FDG PET/CT is a powerful and useful tool in patients with suspected DTC recurrence or residual disease and should be systematically performed when basal Tg level is above 1.2 ng/mL. Thanks to given anatomical informations it can guide surgical re-operation.     

Arthrite rhumatoide traitée par noréthynodrel associée à mestranol: Aspects cliniques et tests de laboratoire

A cause de l''effet favorable de la grossesse sur l''activité de l''arthrite rhumatoïde, on s''est demandé si une pseudo-grossesse, produite par un progestatif de synthèse n''entraînerait pas une rémission du moins partielle de cette maladie.Noréthynodrel associée à mestranol (Enovid), 30 mg./jour, a été administrée à 44 femmes pendant quatre à 24 mois. A cause d''effets secondaires indésirables, 11 patientes furent soustraites de l''investigation. Les résultats s''appuient sur 33 cas. Une rémission apparente complète s''est manifestée chez sept patientes aux stades précoces de la maladie; chez 15, une amélioration objective des signes inflammatoires a été observée; chez quatre, une amélioration subjective seule a été notée; chez sept, il n''y a eu aucune amélioration. Dix-sept femmes sur 36 ont présenté une altération d''un ou plusieurs tests hépatiques. Trois présentèrent un ictère cholestatique. Les 17-OH plasmatiques se sont élevés à trois ou quatre fois la normale.De cette étude il ressort que noréthynodrel associée à mestranol peut produire une atténuation des signes inflammatoires de l''arthrite rhumatoïde. L''effet est palliatif, mitigé et non curatif et ne résulte pas nécessairement de l''état de pseudo-grossesse en soi.     

TEP/TDM à la fluorométhylcholine-(18F) dans l’imagerie de la récidive du cancer de la prostate : jalons pour un PHRC national

This article illustrates, by means of three case reports, whose patients were referred to our PET centre at Tenon hospital, the potential role of fluoromethycholine-(18F) or FCH PET/CT in three different clinical settings of prostate cancer recurrence: early relapse or persistence of neoplastic tissue, restaging of a recurrence detected on MRI while PSA serum levels were less than 1 ng/mL, and detection of an occult recurrence suspected on rising PSA levels. The experience of our team and the analysis of results from literature have permitted to settle a national cooperative study ICHOROPRO that has just been approved, aiming to assess the diagnostic performances and the clinical impact of FCH PET/CT in occult recurrence of prostate cancer.