Évaluation de la sidération myocardique post-effort immédiat par tomoscintigraphie myocardique au 99mTc-sestamibi couplée à l’ECG

AimRepeated episodes of myocardial stunning may lead to chronic ventricular dysfunction. We attempted to assess the parameters related to post-exercise stunning in patients undergoing gated SPECT.MethodsSix hundred patients undergoing a one-day stress/rest ^99mTc-sestamibi gated SPECT were studied. Stress imaging was acquired within 15 minutes after injection. Summed perfusion scores (SSS, SRS and SDS) were calculated using QPS, and LV function assessed using QGS. Stunning was defined as the association of ischemia (SSS ≥ 4 and SDS > 0) and a minimum of 5% decrease in post-stress EF.ResultsIschemia was found in 225 (37.5%) patients. Among these, 67 (30%) showed myocardial stunning. Patients with stunning had a lower rest ESV (47 ± 24 mL vs 65 ± 52 mL, p < 0.0003) and EDV (108 ± 35 mL vs 122 ± 66 mL, p = 0.03), an increased rest LVEF (58 ± 10% vs 52 ± 13%, p < 0.0001) and a decreased post-stress LVEF (49 ± 10% vs 53 ± 13%, p < 0.02) compared to patients with no stunning. The number of myocardial segments showing reversible perfusion defects was increased in patients with stunning (2.7 ± 2.6 vs 1.7 ± 2.1, p < 0.02). On logistic regression, an extent of ischemia greater than two segments and a rest EF greater than 45% were independent predictors of the occurrence of myocardial stunning in patients with ischemia.ConclusionsIn patients with ischemia, exercise-induced stunning was associated with an increased extent of ischemia but also preserved rest ventricular function.     

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.     

Évaluation de l’innervation sympathique cardiaque par la scintigraphie myocardique à la 123I-métaiodobenzylguanidine

Metaiodobenzylguanidine-iode 123 (¹²³I-MIBG) myocardial scintigraphy is one of the few methods available for the objective evaluation of cardiac sympathetic function at the clinical level. Disorders of cardiac sympathetic function play an important role in a variety of heart diseases and particularly in heart failure. MIBG myocardial scintigraphy provides abundance of useful information for evaluation of severity therapeutic effects and prognosis.     

Intérêt de la tomoscintigraphie cardiaque à la 123I-mIBG couplée à la perfusion myocardique dans le diagnostic de l’atrophie multisystématisée

ObjectiveThe aim of this prospective study is to assess the pertinence of using ¹²³I-mIBG myocardial tomoscintigraphy coupled with perfusion scintigraphy as a diagnostic tool, to discriminate between multiple system atrophy (MSA) and idiopathic Parkinson's disease (PD) at first guided by clinical data and L-DOPA tests.Material and methodsForty patients, aged from 43 to 78 years (median 62 years) with Parkinson's syndrome were studied. Nineteen had a diagnosis of PD (criteria of brain bank) and 21 AMS (Gibbs criteria). All were given test to acute L-DOPA. Chest-centered planar imaging (128 × 128 matrix, 5 minutes of duration) is performed at 1 hour and 4 hours after injection of 220 MBq of ¹²³I-mIBG, in addition a non-synchronised tomoscintigraphy (64 × 64 matrix, 32 images of 50 seconds , zoom 1.45) was performed after the 4th hour and 15 minutes after injection of 200 to 400 MBq of ^99mTc-tetrofosmin. Besides neurological data, the parameters retained for comparison purposes with ¹²³I-mIBG cardiac tomoscintigraphy were patients’ age, duration of disease and L-DOPA test results. Two regions of interest (ROI) identical in size and in shape are used for ¹²³I-mIBG uptake quantifications (H/M and washout [Wo]). The first one was placed in projection of mediastinum (M) and the other one in projection of heart (H).ResultsWe found an overall decreased uptake of the myocardial ¹²³I-mIBG without perfusion abnormality in 15 of 19 patients with PD and 11 among them were L-DOPA sensitive (L-DOPA test greater than 30%). Normal tracer uptake with ¹²³I-mIBG associated with an almost quite normal perfusion was seen in 15 of 21 patients with MSA and they were little or not L-DOPA sensitive (L-DOPA test less than 30%). Therefore, 10 discordant cases (25%) between cardiac scintigraphy and clinical evolution of disease with also discordant L-DOPA tests were observed. In the PD group, quantification of data enhanced the diagnostic decision with low heart to mediastinum ratio (H/M) (1.32 ± 0.15 at the early stage and 1.25 ± 0.13 at the later stage). In the MSA group, the uptake of ¹²³I-mIBG (1.66 ± 0.43 at the early stage and 1.72 ± 0.42 at the later stage) was comparable to literature data, however, with significant inter-individual variations. The association of data of scintigraphy with L-DOPA test allows to improve sensitivity in 84% and specificity in 90.5%.ConclusionOur prospective study of 40 cases shows the relevance of cardiac sympathetic postganglionic imaging with ¹²³I-mIBG coupled with myocardial perfusion scintigraphy to discriminate between MSA and PD with a higher sensitivity (71.4%) compared to the test with L-DOPA but a lower specificity (78.9%) than the L-DOPA. The difficulty of diagnosis is firstly linked to damage occurring to both the pre- and postganglionic sympathetic systems in patients with MSA and secondly to the integrity of the sympathetic nerve endings in patients with PD. However, the association of data of scintigraphy with L-DOPA test show a significant improvement of sensibility (84%).     

Faisabilité et précision diagnostique d’un protocole de scintigraphie myocardique synchronisée à l’ECG en deux heures : l’étude Myofast

Aim of the studyTo assess the feasibility of early stress and rest myocardial perfusion and function study using a fast 99mTc-tetrofosmin gated-SPECT protocol in patients with known coronary artery disease.Materials and methodsForty-three patients (pts) (37 M, 6 F, mean age 63.8 ± 9.8 years) underwent a 99mTc-Tetrofosmin gated-SPECT (Axis Picker-Philipps^®) myocardial study and a coronary angiography (CA) within 3 months. Images were acquired (LEHR, eight bins, 40 sec per image) after injection of 99mTc-tetrofosmin (200 to 380 MBq) early (15 min) post-stress (36 dipyridamole, two dobutamine and five ergometric stress), and at rest after 99mTc-tetrofosmin reinjection (600 to 1150 MBq), in a total time not exceeding 2 hours. Processing was performed with QGS^® software using the 17-segment model. Pathological study was defined as a summed difference score (SDS) greater than or equal to 4 4, a fixed defect with summed rest score greater than or equal to 4 and/or LV dysfunction defined as myocardial stunning (variation between stress and rest LVEF greater than or equal to 4 5%), stress LVEF less than or equal to 45% or rest LVEF less than or equal to 40%. Results were compared with CA, and stenosis greater than or equal to 4 50% was considered as significant.ResultsFor 100% the quality of SPECT imaging was good or excellent. For six patients gating was impossible because of arrhythmia. The overall sensitivity, specificity and accuracy were 95%, 50%, and 91%, respectively. The concordance between gated SPECT and CA was moderate (kappa = 0.45, SE = 0.15). Interestingly, early-gated acquisition permitted to underline left ventricular dysfunction in 11 cases (30%), of whom eight had polyvascular disease. Stunning was detected in six of 37 cases (16%), of whom six had polyvascular disease.ConclusionA one-day two-hour 99mTc-tetrofosmin gated-SPECT protocol to assess left ventricular perfusion and function is feasible and accurate. Early gated acquisition proves helpful for detecting post-stress stunning, which is a well known crucial prognostic factor of major cardiac events, and could help to speed up clinical management.     

Évaluation de la TEP au 18F-FDG dans l’exploration de la récidive des carcinomes colorectaux

PurposeThe aim of the study was to evaluate the diagnostic performance, the prognosis factors and the therapeutic impact of 18F-FDG positron emission tomography (FDG-PET) in the detection of recurrent colorectal cancers.MethodsSixty PET/CT with 18F-FDG and CT were performed in 52 patients, at the Paul Papin cancer center between 2003 and 2005, following suspicion of colorectal cancer relapse. The FDG-PET impact on the clinical management was studied by examination of multidisciplinary concertations results. Survival analysis were realized with a mean follow up of 2.2 years.ResultsRecurrence was confirmed for 50 explorations by histologic (n = 32), radiologic (n = 14) or clinical (n = 4) findings. Twenty patients died during the time of the study. On a patient based analysis, FDG-PET sensitivity, specificity and overall accuracy were 90, 90, 90% respectively compared with 74, 50 and 70% for CT. FDG-PET changed the clinical management in 18 cases (30%). A positive FDG-PET signal, more than one hepatic lesion, more than two lymph node lesions detected on FDG-PET and more than two hepatic lesions on CT were characterized as bad prognostic factors for survival. Multivariate analysis showed that the only independent bad prognostic factor was the FDG-PET detection of more than two liver lesions.ConclusionThese results confirmed the important impact of FDG-PET in the clinical management of patients with a suspected recurrence of colorectal cancer.     

Facteurs influençant la détectabilité de l’activité myocardique en caméra à semi-conducteurs

Body weight was already shown to be a major factor for the detectability of myocardial activity with conventional cameras and thus, for the optimization of injected activities and or recording times. This study was aimed to identify the factors affecting this detectability on a new solid-state camera showing a high sensitivity of detection (D.SPECT camera Cyclopharma^®).Patients and methodsThe study population involved 101 patients, who underwent myocardial SPECT with Sestamibi on a one-day stress/rest protocol. Each conventional acquisition (DST-XL General Electric Healthcare^® USA) was immediately followed by a D-SPECT^® one. Myocardial activity was determined on each acquisition in counts per seconds and expressed in fraction of the injected activity for assessing the detectability of myocardial activity.ResultsMyocardial activity was on average 12 ± 3 fold higher when recorded with the D-SPECT^® camera than with the DST-XL^® one. Body weight and especially body mass index (BMI) were the most significant correlates of the detectability of myocardial activity for both cameras. According to these correlations, an increase in the BMI from 25 to 35 kg/m was associated with a 47% decrease in the detectability of myocardial activity at stress with the DST-XL^® and of only 30% with the D-SPECT.ConclusionThe detectability of myocardial activity provided by the D.SPECT camera is dramatically higher than that documented for conventional cameras of the DST-XL^® type and is affected by the increase in body weight and in body mass index but at a lower rate than for the Anger camera.     

L’analyse combinée de la tomoscintigraphie myocardique de stress et de l’angioscanner coronaire pour identifier les artères responsables de l’ischémie

The identification of ischemia-related coronary artery by stress myocardial perfusion SPECT (SPECT-MPS) is difficult, but it is likely that this identification could be easier by fusionning the SPECT images with images from coronary CT angiography (CTA).ObjectiveTo assess the usefulness of the fusion of SPECT-MPS images with CTA images in the identification of ischemia-related coronary arteries.MethodSPECT-MPS and CTA, which had been recorded in a delay ≤ 3 months, were reanalyzed blindly to identify the coronary arterial vessels with (1) stress ischemia at SPECT-MPS and (2) significant coronary stenosis (> 70 %) at CTA. In case of discordance between the two techniques, an analysis was performed while fusioning the SPECT-MPS and CTA images.ResultsThe population included 38 patients, of whom 22 (58 %) had an ischemia at SPECT-MPS. The identification of the ischemia-related vessels was initially discordant between SPECT-MPS and CTA for 17 patients (45 %). After the fusion's analysis, nine out of these 17 patients (53 %) became totally concordant because of modifications in the CTA analysis in six patients and in the SPECT-MPS analysis in only three. A low severity of ischemia was the main correlate of persisting discordances after fusion: 58 % (7/12) of such low severity ischemia were observed in coronary vessels with persisting discordance, but only 24 % (5/27) with concordant coronary vessels (p = 0.02).ConclusionThe identification with SPECT-MPS of the ischemia-related coronary artery is rarely modified by a fusion analysis with CTA images. Discordances between the two techniques remain frequent, even after fusion, but especially in case of low severity SPECT-MPS ischemias.     

Apport de la TEP/TDM au 18FDG dans la stadification initiale et l’évaluation précoce de la réponse thérapeutique des rhabdomyosarcomes pédiatriques

PurposeThe objective of this study was to retrospectively evaluate the impact of positron emission tomography/computed tomography (PET/CT) using fluorine-18-fluorodeoxyglucose (FDG), in comparison with conventional imaging modalities (CIM), for initial staging and early therapy assessment in paediatric rhabdomyosarcoma.Patients and methodsPrior to treatment, 18 patients (age range, 9 months to 18 years) with histologically proven rhabdomyosarcoma underwent FDG PET/CT in addition to CIM (magnetic resonance imaging of primary site, whole body CT and bone scintigraphy). After three courses of chemotherapy, 12 patients underwent FDG PET/CT in addition to CIM. RECIST criteria and visual analysis of FDG uptake were used for assessment of response. The standard of reference was determined by an interdisciplinary tumor board based on imaging material, histopathology and follow-up data (median = 5 years).ResultsPET/CT sensitivity was superior to CIM's concerning lymph node involvement (100% versus 83%, respectively) and metastases detection (100% versus 50%, respectively). PET/CT results changed therapeutic management in 11% of cases. After three courses of chemotherapy, the rate of complete response was 66% with PET/CT versus 8% with CIM. Five percent of patients relapsed during follow-up (median = 5 years).ConclusionThis study confirms that PET/CT depicts important additional information in initial staging of paediatric rhabdomyosarcomas and suggests a superior prognostic value of PET/CT in early response to chemotherapy assessment.