Technetium-99m-labeled macroaggregated albumin lung perfusion scan for diagnosis of hepatopulmonary syndrome: A prospective study comparing brain uptake and whole-body uptake

BACKGROUND Hepatopulmonary syndrome (HPS) is an arterial oxygenation defect induced by intrapulmonary vascular dilatation (IPVD) in the setting of liver disease and/or portal hypertension.This syndrome occurs most often in cirrhotic patients(4%-32%) and has been shown to be detrimental to functional status,quality of life,and survival.The diagnosis of HPS in the setting of liver disease and/or portal hypertension requires the demonstration of IPVD (i.e.,diffuse or localized abnormally dilated pulmonary capillaries and pulmonary and pleural arteriovenous communications) and arterial oxygenation defects,preferably by contrast-enhanced echocardiography and measurement of the alveolar-arterial oxygen gradient,respectively.AIM To compare brain and whole-body uptake of technetium for diagnosing HPS.METHODS Sixty-nine patients with chronic liver disease and/or portal hypertension were prospectively included.Brain uptake and whole-body uptake were calculated using the geometric mean of technetium counts in the brain and lungs and in the entire body and lungs,respectively.RESULTS Thirty-two (46%) patients had IPVD as detected by contrast-enhancedechocardiography.The demographics and clinical characteristics of the patients with and without IPVD were not significantly different with the exception of the creatinine level (0.71±0.18 mg/dL vs 0.83±0.23 mg/dL;P=0.041),alveolararterial oxygen gradient (23.2±13.3 mmHg vs 16.4±14.1 mmHg;P=0.043),and arterial partial pressure of oxygen (81.0±12.1 mmHg vs 90.1±12.8 mmHg;P=0.004).Whole-body uptake was significantly higher in patients with IPVD than in patients without IPVD (48.0%±6.1%vs 40.1%±8.1%;P=0.001).The area under the curve of whole-body uptake for detecting IPVD was significantly higher than that of brain uptake (0.75 vs 0.54;P=0.025).The optimal cut-off values of brain uptake and whole-body uptake for detecting IPVD were 5.7%and 42.5%,respectively,based on Youden’s index.The sensitivity,specificity,and accuracy of brain uptake> 5.7%and whole-body uptake> 42.5%for detecting IPVD were23%,89%,and 59%and 100%,52%,and 74%,respectively.CONCLUSION Whole-body uptake is superior to brain uptake for diagnosing HPS.

A Simple and Quick Screening Method for Intrapulmonary Vascular Dilation in Cirrhotic Patients Based on Machine Learning

Background and Aims:Screening for hepatopulmonary syndrome in cirrhotic patients is limited due to the need to perform contrast enhanced echocardiography(CEE)and arterial blood gas(ABG)analysis.We aimed to develop a simple and quick method to screen for the presence of intrapulmonary vascular dilation(IPVD)using noninvasive and easily available variables with machine learning(ML)algorithms.Methods:Cirrhotic patients were enrolled from our hospital.All eligible patients underwent CEE,ABG analysis and physical examination.We developed a twostep model based on three ML algorithms,namely,adaptive boosting(termed AdaBoost),gradient boosting decision tree(termed GBDT)and eXtreme gradient boosting(termed Xgboost).Noninvasive variables were input in the first step(the NI model),and for the second step(the NIBG model),a combination of noninvasive variables and ABG results were used.Model performance was determined by the area under the curve of receiver operating characteristics(AUCROCs),precision,recall,F1-score and accuracy.Results:A total of 193 cirrhotic patients were ultimately analyzed.The AUCROCs of the NI and NIBG models were 0.850(0.738–0.962)and 0.867(0.760–0.973),respectively,and both had an accuracy of 87.2%.For both negative and positive cases,the recall values of the NI and NIBG models were both 0.867(0.760–0.973)and 0.875(0.771–0.979),respectively,and the precisions were 0.813(0.690–0.935)and 0.913(0.825–1.000),respectively.Conclusions:We developed a two-step model based on ML using noninvasive variables and ABG results to screen for the presence of IPVD in cirrhotic patients.This model may partly solve the problem of limited access to CEE and ABG by a large numbers of cirrhotic patients.