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International audience; BackgroundCardiac uptake on technetium-99m whole-body scintigraphy (WBS) is almost pathognomonic of transthyretin cardiac amyloidosis. The rare false positives are often related to light-chain cardiac amyloidosis. However, this scintigraphic feature remains largely unknown, leading to misdiagnosis despite characteristic images. A retrospective review of all WBSs in a hospital database to detect those with cardiac uptake may allow the identification of undiagnosed patients.ObjectivesThe authors sought to develop and validate the first deep learning–based model that automatically detects significant cardiac uptake (≥Perugini grade 2) on WBS from large hospital databases in order to retrieve patients at risk of cardiac amyloidosis.MethodsThe model is based on a convolutional neural network with image-level labels. The performance evaluation was performed with C-statistics using a 5-fold cross-validation scheme stratified so that the proportion of positive and negative WBSs remained constant across folds and using an external validation data set.ResultsThe training data set consisted of 3,048 images: 281 positives (≥Perugini 2) and 2,767 negatives. The external validation data set consisted of 1,633 images: 102 positives and 1,531 negatives. The performance of the 5-fold cross-validation and external validation was as follows: 98.9% (± 1.0) and 96.1% for sensitivity, 99.5% (± 0.4) and 99.5% for specificity, and 0.999 (SD = 0.000) and 0.999 for the area under the curve of the receiver-operating characteristic curves. Sex, age

DEAR SIR, We read with great interest the recent letter to the Editor by Lavinia Monaco et al. [1] about the article by Jeeban P. Das et al. [2] that were both published in your European Journal of Nuclear Medicine and Molecular Imaging. In six patients with a laboratory-confirmed diagnosis of COVID-19 and a moderate or high pre-test probability of pulmonary embolism (PE), perfusion (Q)-single-photon emission computed tomography (SPECT)/CT was found positive in 4/6 of patients with bilateral and segmental PE in 3/4 of patients. [...]

In 18F-fluorodeoxyglucose PET/CT, respiratory motion induces bias in image interpretations (i.e. organ misregistration or lesion omission/underestimation).The present study applied our custom gating method (referred to as 'CT-based gated PET' and that has already been validated by our research group) to PET imaging of the liver and compared its per lesion sensitivity with that of standard clinical (i.e. ungated) PET.A total of 13 patients scheduled for liver surgery were referred to our department for PET/CT imaging. Each patient underwent both ungated and CT-based gated PET imaging protocols. Two independent, blinded observers interpreted the two sets of PET images and reached a consensus when necessary. Image interpretations were combined with histological analysis and/or intraoperative ultrasound examination to compute each method's per lesion sensitivity and true positive fraction. Analyses were also performed by considering lesions according to their size (longest axis over 10 mm or over 15 mm).Forty-eight lesions were confirmed by pathology reports. When considering all the uptakes, the ungated and the CT-based gated PET methods had sensitivities of 54.2 and 64.6% (P=0.025) and true positive fractions of 83.9 and 86.1%, respectively. When considering uptakes greater than 10 mm in size, ungated and CT-based gated PET had sensitivities of 74.3 and 88.6% (P=0.025), respectively. For lesions greater than 15 mm in size, the corresponding sensitivities were 85.2 and 100% (P=0.046).CT-based gated PET yielded a higher lesion-based sensitivity than routine, ungated PET did. Hence, this method improves the detection of intrahepatic colorectal metastases--especially for lesions that are close in size to the detection limit of the PET gantry.

Background Respiratory motion is known to deteriorate positron emission tomography (PET) images and may lead to potential diagnostic errors when a standardized uptake value (SUV) cut-off threshold is used to discriminate between benign and malignant lesions. Purpose To evaluate and compare ungated and respiratory-gated 18F-fluorodeoxyglucose PET/computed tomography (CT) methods for the characterization of pulmonary nodules. Material and Methods The list-mode acquisition during respiratory-gated PET was combined with a short breath-hold CT scan to form the CT-based images. We studied 48 lesions in 43 patients. PET images were analyzed in terms of the maximum SUV (SUVmax) and the lesion location. Results Using receiver-operating characteristic (ROC) curves, the optimal SUV cut-off thresholds for the ungated and CT-based methods were calculated to be 2.0 and 2.2, respectively. The corresponding sensitivity values were 83% and 92%, respectively, with a specificity of 67% for both methods. The two methods gave equivalent performance levels for the upper and middle lobes (sensitivity 93%, specificity 62%). They differed for the lower lobes, where the CT-based method outperformed the ungated method (sensitivity values of 90% and 70%, respectively, and a specificity of 73% with both methods) – especially for lesions smaller than 15 mm. Conclusion The CT-based method increased sensitivity and did not diminish specificity, compared with the ungated method. It was more efficient than the ungated method for imaging the lower lobes and smallest lesions, which are most affected by respiratory motion.

Aim To assess the extent to which bone marrow scintigraphy (BMS) makes the interpretation of leucocyte scintigraphy (LS) easier and improves its diagnostic value. Methods Seventy-three 111In LSs, 99mTc hydroxymethylene diphosphonate bone scintigraphies (BSs) and 99mTc sulfur colloid BMSs were performed in 60 patients with suspected infection related to a hip prosthesis or knee prosthesis, either in situ (+group, n = 43) or after removal for septic loosening (-group, n = 30). Bacteriological samples were obtained from all patients. LS was interpreted together with BS (LS-BS) or with BMS (LS-BMS) by three independent readers. Results The concordance among readers, estimated by the kappa test, was average with LS-BS (kappa/kappam coefficients = 0.58, 0.58 and 0.46, respectively, for the three pairs of readers) and excellent with LS-BMS (kappa/kappam coefficients = 1.00 for the three pairs of readers). With LS-BS, 64/219 interpretations were equivocal whereas only one was equivocal with LS-BMS. Sensitivity, specificity and accuracy of LS-BMS were, respectively, 80%, 94% and 91% in the +group, and 33%, 100% and 93% in the -group. Conclusion We conclude that (1) the interpretation of the results for LS-BMS is very easy, in contrast to LS-BS; (2) the diagnostic value of LS-BMS for detecting infected joint prostheses is good; and (3) additional data are needed to assess the accuracy of LS-BMS when the prosthesis has been removed.

Experimentally, leptin has a positive effect on bone mass when infused intravenously, but a negative one after intracerebroventricular administration. Renal failure increases its serum level above the concentration beyond which its transport to the brain may be saturated. Thus, we tested, in a chronic haemodialysis population, the hypothesis of a positive relationship between serum leptin and bone mineral density (BMD) when serum levels are above this threshold.Serum leptin (using a two-site RIA), and BMD at the femoral neck, midshaft, and ultradistal radius, as measured by DEXA, were assessed in 17 female and 16 male chronic dialysis patients, with comparable calcium and phosphate metabolism, age and dialysis duration.Polynomial regression analysis showed a U-shaped correlation between BMD Z-score, with an inflexion point, which may correspond to the concentration threshold at which leptin blood-brain carrier is saturated. Linear regression analysis showed no correlation between BMD and serum leptin levels below these points but a significant positive correlation between BMD at the two radius sites and leptin levels above these points. The correlation remained significant after adjustment for BMI, serum PTH and duration of dialysis. Leptin levels were twice as high in female patients and associated with higher BMD Z-scores close to zero.This study suggests a bone-sparing effect of serum leptin in haemodialysis patients only when the serum levels of leptin were higher than the presumed threshold of blood-brain transport saturation. Higher leptin levels in post-menopausal female haemodialysis patients than in male patients may account for their slower bone loss with ageing.

The aim of this cross-sectional multicenter study was to determine the prevalence of and risk factors for hypothyroidism in human immunodeficiency virus (HIV)-infected patients. Free T4, free T3, and thyroid-stimulating hormone levels were determined. Data on age, sex, weight variation, smoking status, duration of HIV infection, Centers for Disease Control and Prevention disease stage, CD4 cell count, HIV RNA load, lipodystrophy, HIV-hepatitis C virus coinfection, and antiretroviral treatment (type of drugs and total cumulative dose) were collected. The prevalence study included 350 HIV-infected patients. Sixteen percent of patients had hypothyroidism: 2.6% had overt hypothyroidism, 6.6% had subclinical hypothyroidism, and 6.8% had a low free T4 level. The prevalence of subclinical hypothyroidism was higher among HIV-infected men than among HIV-infected women. A case-control study was conducted that compared hypothyroid (n=56) and euthyroid (n=287) patients. In the multivariate analysis, receipt of stavudine and low CD4 cell count were associated with hypothyroidism. Therefore, screening may be indicated for patients, especially men, who have received stavudine or have decreased CD4 cell counts.

Background. Sevelamer hydrochloride was recently proposed as a phosphate binder to prevent hypercalcaemia in place of calcium alkaline salts in dialysis patients. So far, it has been evaluated only in patients receiving calcitriol, without comparison with CaCO3 alone, although the latter was found to be as effective as the combination of calcitriol and Al(OH)3 in suppressing parathyroid hormone (PTH) without inducing hypercalcaemia and to have a better lowering effect on serum phosphate. Moreover, this bile salt binder may decrease serum 25-OH vitamin D. Therefore, we compared for 5 months two strategies for controlling moderate hyperparathyroidism: CaCO3 alone vs sevelamer in conjunction with measures to increase calcium balance. Methods. Forty-two patients were randomized: 21 continued their treatment with 4.8 guday CaCO3 and 21 were switched to sevelamer (initial dose: 2.4 guday, increased to 4.4 guday). Each month, when serumcorrected calcium decreased below 2.30 mmolul, dialysate calcium was increased or alphacalcidol was given at each dialysis session, according to serum PO4 levels. The following parameters were monitored: serum Ca, PO4, bicarbonate and protein, weekly; and serum PTH, 25-OH vitamin D and total, LDL and HDL cholesterol monthly. Results. Except for higher serum phosphate at month 1, lower serum bicarbonate at month 2 and lower LDL cholesterol at month 5 in the sevelamer group, no difference was found between the two groups. Compared with baseline levels, PTH increased and 25-OH vitamin D decreased significantly in both groups, these two parameters being inversely correlated. Conclusions. Given comparable control of plasma calcium, phosphate and 25-OH vitamin D, PTH control is comparable in both strategies. Sevelamer does not induce greater vitamin D depletion than CaCO3. The transient decrease of serum bicarbonate after discontinuation of CaCO3 in the sevelamer group suggests a less optimal prevention of acidosis. The sevelamer-induced decrease in LDL cholesterol gives this drug a potential advantage in cardiovascular prevention.

Respiratory motion causes uptake in positron emission tomography (PET) images of chest structures to spread out and misregister with the CT images. This misregistration can alter the attenuation correction and thus the quantisation of PET images. In this paper, we present the first clinical results for a respiratory-gated PET (RG-PET) processing method based on a single breath-hold CT (BH-CT) acquisition, which seeks to improve diagnostic accuracy via better PET-to-CT co-registration. We refer to this method as "CT-based" RG-PET processing.Thirteen lesions were studied. Patients underwent a standard clinical PET protocol and then the CT-based protocol, which consists of a 10-min List Mode RG-PET acquisition, followed by a shallow end-expiration BH-CT. The respective performances of the CT-based and clinical PET methods were evaluated by comparing the distances between the lesions' centroids on PET and CT images. SUV(MAX) and volume variations were also investigated.The CT-based method showed significantly lower (p = 0.027) centroid distances (mean change relative to the clinical method = -49%; range = -100% to 0%). This led to higher SUV(MAX) (mean change = +33%; range = -4% to 69%). Lesion volumes were significantly lower (p = 0.022) in CT-based PET volumes (mean change = -39%: range = -74% to -1%) compared with clinical ones.A CT-based RG-PET processing method can be implemented in clinical practice with a small increase in radiation exposure. It improves PET-CT co-registration of lung lesions and should lead to more accurate attenuation correction and thus SUV measurement.

Steady-state captopril renography (SSCR) is an original technique for assessing the captopril-induced increase in technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) mean parenchymal transit time (MPTT) in kidneys affected with functional renal artery stenosis (RAS). The steady-state parenchymal activity achieved by constant infusion of 99mTc-MAG3 is directly linked to the MPTT of the radiopharmaceutical. This steady-state parenchymal activity was continuously monitored from 15 min before to 60 min after a single dose of captopril in order to detect possible disruption of the steady state. SSCR was performed in 11 hypertensive patients with unilateral RAS and in two with RAS of a solitary kidney before renal revascularization (RR). In four of these patients, an additional SSCR was performed after RR. Of the ten patients whose hypertension was cured or improved by RR, one presented an uninterpretable SSCR and six presented a positive SSCR on the affected side. Control SSCR performed in four of these six patients was bilaterally negative. SSCR was also bilaterally negative in the three patients who showed no blood pressure response to RR. These preliminary results tend to indicate that, in spite of the stability of pre- and post-captopril hydration and data acquisition conditions allowed by this steady-state technique, the sensitivity is lower than expected. However, the reason for the false-negative results does not seem to be inherent to SSCR.

Cyclosporine bone remodeling effect prevents steroid osteopenia after kidney transplantation.BackgroundIt is well established that prednisone above 7.5 mg/day may induce osteopenia in association with decreased bone formation. In contrast, the effect of cyclosporine on bone remodeling and bone mineral density (BMD) is controversial. Multiple confounding factors explain this controversy, especially after renal transplantation.MethodsFifty-two renal transplanted patients never exposed to aluminum while on dialysis were selected because they had no rejection and no hypercalcemia for 24 months while being treated with low dose prednisone/cyclosporine A (daily dose at 10 mg and 4.8 mg/kg, respectively, beyond 3 months). Bone remodeling markers (BRMs; plasma osteocalcin, bone and total alkaline phosphatases for formation, and urinary pyridinolines for resorption) were sequentially measured together with plasma creatinine, intact parathyroid hormone (PTH) and 25 OH vitamin D and cyclosporine from day 0 to 24 months. BMD was measured at 3, 6, 12, and 24 months by quantitative computerized tomography (QCT) at the lumbar spine and by double-energy x-ray absorptiometry (DEXA) at this site, as well as at the femoral neck, radius shaft, and ultradistal (UD) radius.ResultsPlasma concentrations of creatinine, PTH, and 25 OH vitamin D initially decreased and stabilized beyond three months at 137 μmol/L, 1.5 the upper limit of normal (ULN) and 11 ng/mL, respectively. All BRM increased significantly above the ULN at six months and then decreased. The BMD Z score at three months was low at all sites measured by DEXA and QCT. Follow-up measurements showed stability of absolute value and of Z score at all sites measured by DEXA. A comparison of the lumbar QCT Z score, which was available in 42 patients at 3 and 24 months, showed an increase in 28 and a decrease in 14, so that the increase for the whole group was significant (P < 0.04). Compared with patients with a decreased Z score, those with an increased Z score had significantly higher cyclosporine and lower prednisone dosages and a greater BRM increase at six months, whereas age, sex ratio, and plasma creatinine, PTH and 25 OH vitamin D were comparable and stable from months 3 through 24. The mean trough level of cyclosporine for the first six months was positively correlated to osteocalcin and total alkaline phosphatase increase at six months, and both bone formation and resorption marker increases were significantly correlated to the lumbar QCT Z score increase at 24 months.ConclusionsCombined low-dose prednisone and cyclosporine immunosuppression are associated with a stabilization of BMD measured at all sites with DEXA 3 to 24 months after renal transplantation and with a prevention of age-related loss of vertebral trabecular bone, as shown by the significant increase in lumbar spine QCT Z score. It is suggested that cyclosporine, together with the decrease of prednisone dosage but independent of renal function, PTH, and vitamin D status, contributes to a transient stimulation of bone remodeling at six months, which counterbalances the deleterious effect of prednisone on bone formation and BMD.

La TEP-FDG est une modalité d'imagerie officiellement intégrée au bilan diagnostique de l'endocardite infectieuse (EI) depuis 2015. Cependant, sa sensibilité, en particulier en présence de sondes d'électrostimulation, n'est pas totalement satisfaisante. Une innovation technologique, les photodiodes à base de silicium (SiPM), permet d'augmenter significativement la résolution spatiale de la TEP. L'objectif de ce travail était donc d'évaluer les performances de la SiPM/TEP-FDG pour le diagnostic d'EI. Étude rétrospective monocentrique portant sur les patients adressés dans le service de médecine nucléaire du CHU d'Amiens entre janvier 2018 et février 2020 pour suspicion d'EI. Les performances de l'analyse visuelle de la TEP ont été calculées en utilisant comme gold standard le diagnostic final retenu par le clinicien. 57 patients ont été inclus. 17 TEP-FDG ont été interprétées « positives » et 40 « négatives ». La sensibilité et la spécificité de l'examen étaient respectivement de 64% et 96,9% pour l'EI, 83,3% et 95,7% pour l'EI sur prothèse valvulaire et 38,5% et 100% pour l'EI sur sonde d'électrostimulation. La TEP-FDG a permis de reclasser 50% des patients classés « EI possible » selon les critères de Duke modifiés. Les résultats obtenus sont conformes à ceux de la littérature : l'innovation apportée par les détecteurs SiPM ne semble pas révolutionner les performances de la TEP-FDG. La fixation myocardique résiduelle du FDG malgré le régime préconisé ainsi que la petite taille et la mobilité des lésions sont les deux principales difficultés rencontrées. Nous proposons pour chacune une voie d'amélioration.

La tomographie par émission de positons à la fluorocholine (TEP-FCH) prend une place croissante dans le bilan préchirurgical d'hyperparathyroïdie primaire (HPTP) depuis quelques années. Les objectifs de ce travail étaient de mesurer les performances de la TEP-FCH dans cette indication et d'évaluer les pratiques du service de médecine nucléaire du CHU Amiens-Picardie concernant cet examen récent. Ce travail rétrospectif monocentrique mené au CHU Amiens-Picardie concernait les patients ayant bénéficié d'une TEP-FCH dans le bilan préchirurgical d'HPTP après scintigraphie au sestamibi et échographie cervicale négatifs ou discordants. Le gold standard était la chirurgie avec analyse histologique et le suivi biologique. Des mesures quantitatives sur les lésions hypermétaboliques étaient réalisées et comparées entre deux délais post-injection d'acquisition des images. Vingt-deux patients ont été inclus dans l'étude. Dix-huit examens TEP-FCH étaient de vrais positifs, 3 étaient faux négatifs, 1 était faux positif. Dix-sept des patients opérés sur la base de la TEP-FCH (95%) ont pu bénéficier d'une exploration cervicale unilatérale curative. Les sensibilité et VPP de la TEP-FCH étaient de 82% et 95% respectivement en analyse par patient. Les analyses quantitatives montraient un contraste lésion sur bruit de fond environnant significativement plus élevé sur les acquisitions à 30 minutes que sur les acquisitions à 5 minutes post-injection (p = 0,03). La TEP-FCH présente de bonnes performances pour la détection et la localisation de glandes parathyroïdes hyperfonctionnelles dans le bilan préchirurgical d'HPTP lorsque le bilan d'imagerie conventionnelle est négatif ou discordant. L'examen permet de mener une chirurgie élective avec succès dans 77% des cas, évitant une exploration cervicale bilatérale aux risques de complication accrus. La TEP-FCH pourrait remplacer la scintigraphie au sestamibi en première intention dans cette indication mais d'autres études, notamment médico-économiques sont nécessaires pour le confirmer.