Deep Learning on Bone Scintigraphy to Detect Abnormal Cardiac Uptake at Risk of Cardiac Amyloidosis.

BACKGROUND: Cardiac 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. OBJECTIVES: The authors sought to develop and validate a 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. METHODS: The 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. RESULTS: The training data set consisted of 3,048 images: 281 positives (Perugini grade ≥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 <90 years, body mass index, injection-acquisition delay, radionuclides, and the indication of WBS only slightly affected performances. CONCLUSIONS: The authors' detection model is effective at identifying patients with cardiac uptake Perugini grade ≥2 on WBS and may help in the diagnosis of patients with cardiac amyloidosis.

Value of Positron Emission Tomography Coupled With Computed Tomography for the Diagnosis of Inflammatory Syndrome of Unknown Origin in an Internal Medicine Department.

Objective: To evaluate the usefulness of positron emission tomography (PET) coupled with computed tomography (CT) in the diagnostic workup for inflammatory syndrome of undetermined origin (IUO) and to determine the diagnostic delay in an internal medicine department. Patients and methods: We retrospectively studied a cohort of patients for whom a PET/CT scan had been prescribed in an indication of IUO in an internal medicine department (Amiens University Medical Center, Amiens, France) between October 2004 and April 2017. The patients were grouped according to the PET/CT findings: very useful (enabling an immediate diagnosis), useful, not useful, and misleading. Results: We analyzed 144 patients. The median (interquartile range) age was 67.7 years (55.8-75.8 years). The final diagnosis was an infectious disease in 19 patients (13.2%), cancer in 23 (16%), inflammatory disease in 48 (33%), and miscellaneous diseases in 12 (8.3%). No diagnosis was made in 29.2% of the cases; half of the remaining had a spontaneously favorable outcome. Fever was observed in 63 patients (43%). Positron emission tomography coupled with CT was determined to be very useful in 19 patients (13.2%), useful in 37 (25.7%), not useful in 63 (43.7%), and misleading in 25 (17.4%). The median diagnostic delay (ie, the time interval between the first admission and a confirmed diagnosis) was significantly shorter in the useful (71 days [38-170 days]) and very useful (55 days [13-79 days]) groups than that in the not useful group (175 days [51-390 days]; P<.001). The median time interval between the PET/CT scan and the diagnosis was twice as long in the not useful group than that in the pooled misleading, useful, or very useful groups (P=.03). In a univariate analysis, the poor overall condition (P=.007) and the absence of fever (P=.005) were predictive of usefulness of PET/CT. Conclusion: Positron emission tomography coupled with CT seems to be useful in the diagnosis of IUO and might shorten the diagnostic delay.

Improved imaging of intrahepatic colorectal metastases with 18F-fluorodeoxyglucose respiratory-gated positron emission tomography.

BACKGROUND: In 18F-fluorodeoxyglucose PET/CT, respiratory motion induces bias in image interpretations (i.e. organ misregistration or lesion omission/underestimation). OBJECTIVE: 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. METHODS: 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). RESULTS: 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). CONCLUSION: 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.

Respiratory-gated 18F-FDG PET imaging in lung cancer: effects on sensitivity and specificity.

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 (SUV(max)) 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.

Initial clinical results for breath-hold CT-based processing of respiratory-gated PET acquisitions.

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Bone mineral density directly correlates with elevated serum leptin in haemodialysis patients.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Increased prevalence of hypothyroidism among human immunodeficiency virus-infected patients: a need for screening.

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.

Sevelamer hydrochloride with or without alphacalcidol or higher dialysate calcium vs calcium carbonate in dialysis patients: an open-label, randomized study.

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 CaCO(3) 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: CaCO(3) alone vs sevelamer in conjunction with measures to increase calcium balance. METHODS: Forty-two patients were randomized: 21 continued their treatment with 4.8 g/day CaCO(3) and 21 were switched to sevelamer (initial dose: 2.4 g/day, increased to 4.4 g/day). Each month, when serum-corrected calcium decreased below 2.30 mmol/l, dialysate calcium was increased or alphacalcidol was given at each dialysis session, according to serum PO(4) levels. The following parameters were monitored: serum Ca, PO(4), 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 CaCO(3). The transient decrease of serum bicarbonate after discontinuation of CaCO(3) 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.