Hepatopulmonary syndrome (HPS) is characterized by abnormalities in blood oxygenation caused by the presence of intrapulmonary vascular dilations (IPVD) in the context of liver disease, generally at a cirrhotic stage....Hepatopulmonary syndrome (HPS) is characterized by abnormalities in blood oxygenation caused by the presence of intrapulmonary vascular dilations (IPVD) in the context of liver disease, generally at a cirrhotic stage. Knowledge about the subject is still only partial. The majority of the information about the etiopathogenesis of HPS has been obtained through experiments on animals. Reported prevalence in patients who are candidates for a liver transplantation (LT) varies between 4% and 32%, with a predominance of mild or moderate cases. Although it is generally asymptomatic it does have an impact on their quality of life and survival. The diagnosis requires taking an arterial blood gas sample of a seated patient with alveolar-arterial oxygen gradient (AaO<sub>2</sub>) ≥ 15 mm Hg, or ≥ 20 mm Hg in those over 64 years of age. The IPVD are identified through a transthoracic contrast echocardiography or a macroaggregated albumin lung perfusion scan (<sup>99m</sup>Tc-MAA). There is currently no effective medical treatment. LT has been shown to reverse the syndrome and improve survival rates, even in severe cases. Therefore the policy of prioritizing LT would appear to increase survival rates. This paper takes a critical and clinical look at the current understanding of HPS, as well as the controversies surrounding it and possible future research.展开更多
AIM: To compare different multidetector computed tomography (MDCT) protocols to optimize pancreatic contrast enhancement. METHODS: Forty consecutive patients underwent contrast-enhanced biphasic MDCT (arterial and por...AIM: To compare different multidetector computed tomography (MDCT) protocols to optimize pancreatic contrast enhancement. METHODS: Forty consecutive patients underwent contrast-enhanced biphasic MDCT (arterial and portalvenous phase) using a 64-slice MDCT. In 20 patients, the scan protocol was adapted from a previously used 40-channel MDCT scanner with arterial phase scanning initiated 11.1 s after a threshold of 150 HU was reached in the descending aorta, using automatic bolus tracking (Protocol 1). The 11.1-s delay was changed to 15 s in the other 20 patients to reflect the shorter scanning times on the 64-channel MDCT compared to the previous 40-channel system (Protocol 2). HU values were measured in the head and tail of the pancreas in the arterial and portal-venous phase. RESULTS: Using an 11.1-s delay, 74.2 HU (head) were measured on average in the arterial phase and 111.2 HU (head) were measured using a 15-s delay (P <0.0001). For the pancreatic tail, the average attenuation level was 76.73 HU (11.1 s) and 99.89 HU (15 s) respectively (P = 0.0002). HU values were also significantly higher in the portal-venous phase [pancreatic head: 70.5 HU (11.1 s) vs 84.0 HU (15 s) (P = 0.0014); pancreatic tail: 67.45 HU (11.1 s) and 77.18 HU (15 s) using Protocol 2 (P = 0.0071)]. CONCLUSION: Sixty-four MDCT may yield a higher contrast in pancreatic study with (appropriate) optimization of scan delay time.展开更多
文摘Hepatopulmonary syndrome (HPS) is characterized by abnormalities in blood oxygenation caused by the presence of intrapulmonary vascular dilations (IPVD) in the context of liver disease, generally at a cirrhotic stage. Knowledge about the subject is still only partial. The majority of the information about the etiopathogenesis of HPS has been obtained through experiments on animals. Reported prevalence in patients who are candidates for a liver transplantation (LT) varies between 4% and 32%, with a predominance of mild or moderate cases. Although it is generally asymptomatic it does have an impact on their quality of life and survival. The diagnosis requires taking an arterial blood gas sample of a seated patient with alveolar-arterial oxygen gradient (AaO<sub>2</sub>) ≥ 15 mm Hg, or ≥ 20 mm Hg in those over 64 years of age. The IPVD are identified through a transthoracic contrast echocardiography or a macroaggregated albumin lung perfusion scan (<sup>99m</sup>Tc-MAA). There is currently no effective medical treatment. LT has been shown to reverse the syndrome and improve survival rates, even in severe cases. Therefore the policy of prioritizing LT would appear to increase survival rates. This paper takes a critical and clinical look at the current understanding of HPS, as well as the controversies surrounding it and possible future research.
文摘AIM: To compare different multidetector computed tomography (MDCT) protocols to optimize pancreatic contrast enhancement. METHODS: Forty consecutive patients underwent contrast-enhanced biphasic MDCT (arterial and portalvenous phase) using a 64-slice MDCT. In 20 patients, the scan protocol was adapted from a previously used 40-channel MDCT scanner with arterial phase scanning initiated 11.1 s after a threshold of 150 HU was reached in the descending aorta, using automatic bolus tracking (Protocol 1). The 11.1-s delay was changed to 15 s in the other 20 patients to reflect the shorter scanning times on the 64-channel MDCT compared to the previous 40-channel system (Protocol 2). HU values were measured in the head and tail of the pancreas in the arterial and portal-venous phase. RESULTS: Using an 11.1-s delay, 74.2 HU (head) were measured on average in the arterial phase and 111.2 HU (head) were measured using a 15-s delay (P <0.0001). For the pancreatic tail, the average attenuation level was 76.73 HU (11.1 s) and 99.89 HU (15 s) respectively (P = 0.0002). HU values were also significantly higher in the portal-venous phase [pancreatic head: 70.5 HU (11.1 s) vs 84.0 HU (15 s) (P = 0.0014); pancreatic tail: 67.45 HU (11.1 s) and 77.18 HU (15 s) using Protocol 2 (P = 0.0071)]. CONCLUSION: Sixty-four MDCT may yield a higher contrast in pancreatic study with (appropriate) optimization of scan delay time.
