Multiyear in-situ L-band microwave radiometry of land surface processes on the Tibetan Plateau.

We report a unique multiyear L-band microwave radiometry dataset collected at the Maqu site on the eastern Tibetan Plateau and demonstrate its utilities in advancing our understandings of microwave observations of land surface processes. The presented dataset contains measurements of L-band brightness temperature by an ELBARA-III microwave radiometer in horizontal and vertical polarization, profile soil moisture and soil temperature, turbulent heat fluxes, and meteorological data from the beginning of 2016 till August 2019, while the experiment is still continuing. Auxiliary vegetation and soil texture information collected in dedicated campaigns are also reported. This dataset can be used to validate the Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) satellite based observations and retrievals, verify radiative transfer model assumptions and validate land surface model and reanalysis outputs, retrieve soil properties, as well as to quantify land-atmosphere exchanges of energy, water and carbon and help to reduce discrepancies and uncertainties in current Earth System Models (ESM) parameterizations. Measurement cases in winter, pre-monsoon, monsoon and post-monsoon periods are presented.

Evaluating soil moisture retrievals from ESA's SMOS and NASA's SMAP brightness temperature datasets.

Two satellites are currently monitoring surface soil moisture (SM) using L-band observations: SMOS (Soil Moisture and Ocean Salinity), a joint ESA (European Space Agency), CNES (Centre national d'études spatiales), and CDTI (the Spanish government agency with responsibility for space) satellite launched on November 2, 2009 and SMAP (Soil Moisture Active Passive), a National Aeronautics and Space Administration (NASA) satellite successfully launched in January 2015. In this study, we used a multilinear regression approach to retrieve SM from SMAP data to create a global dataset of SM, which is consistent with SM data retrieved from SMOS. This was achieved by calibrating coefficients of the regression model using the CATDS (Centre Aval de Traitement des Données) SMOS Level 3 SM and the horizontally and vertically polarized brightness temperatures (TB) at 40° incidence angle, over the 2013 - 2014 period. Next, this model was applied to SMAP L3 TB data from Apr 2015 to Jul 2016. The retrieved SM from SMAP (referred to here as SMAP_Reg) was compared to: (i) the operational SMAP L3 SM (SMAP_SCA), retrieved using the baseline Single Channel retrieval Algorithm (SCA); and (ii) the operational SMOSL3 SM, derived from the multiangular inversion of the L-MEB model (L-MEB algorithm) (SMOSL3). This inter-comparison was made against in situ soil moisture measurements from more than 400 sites spread over the globe, which are used here as a reference soil moisture dataset. The in situ observations were obtained from the International Soil Moisture Network (ISMN; https://ismn.geo.tuwien.ac.at/) in North of America (PBO_H2O, SCAN, SNOTEL, iRON, and USCRN), in Australia (Oznet), Africa (DAHRA), and in Europe (REMEDHUS, SMOSMANIA, FMI, and RSMN). The agreement was analyzed in terms of four classical statistical criteria: Root Mean Squared Error (RMSE), Bias, Unbiased RMSE (UnbRMSE), and correlation coefficient (R). Results of the comparison of these various products with in situ observations show that the performance of both SMAP products i.e. SMAP_SCA and SMAP_Reg is similar and marginally better to that of the SMOSL3 product particularly over the PBO_H2O, SCAN, and USCRN sites. However, SMOSL3 SM was closer to the in situ observations over the DAHRA and Oznet sites. We found that the correlation between all three datasets and in situ measurements is best (R > 0.80) over the Oznet sites and worst (R = 0.58) over the SNOTEL sites for SMAP_SCA and over the DAHRA and SMOSMANIA sites (R= 0.51 and R= 0.45 for SMAP_Reg and SMOSL3, respectively). The Bias values showed that all products are generally dry, except over RSMN, DAHRA, and Oznet (and FMI for SMAP_SCA). Finally, our analysis provided interesting insights that can be useful to improve the consistency between SMAP and SMOS datasets.

Reappraisal of percutaneous transhepatic cholangioscopic lithotomy for primary hepatolithiasis.

BACKGROUND: A review of the literature pertaining to percutaneous transhepatic cholangioscopic lithotomy (PTCSL) showed that more than 50% of reported patients had undergone earlier biliary surgery. METHODS: A retrospective study investigated 74 patients undergoing initial PTCSL for hepatolithiasis who had undergone no prior biliary surgery or manipulation. The patients were followed for 1 to 23 years after PTCSL for effective evaluation of the procedure outcome. RESULTS: Complete clearance of hepatolithiasis was achieved for 61 (82%) patients. The incomplete clearance rate was higher for patients with intrahepatic duct stricture (11/37 [30%] vs 2/37 [5%]; p < 0.05), although it showed no relation to the actual lobar distribution of hepatolithiasis (left: 7/41 [17%] vs right: 2/11 [18%] vs bilateral: 4/22 [18%]; p < 0.05). The recurrence rate for hepatolithiasis also was higher for patients with intrahepatic duct stricture (18/26 [69%] vs 13/35 [37%]; p < 0.05), but the recurrence rate showed no relation to the lobar distribution of hepatolithiasis (left: 18/34 [53%] vs right: 4/9 [44%] vs bilateral: 9/18 [50%] p > 0.05) or the presence of gallbladder stones (5/12 [42%] vs 26/49 [53%]; p > 0.05). Patients showing the coexistence of retained or recurrent hepatolithiasis demonstrated a higher incidence of recurrent cholangitis (57% [13/23] vs 14% [7/51]; p < 0.01) or cholangiocarcinoma (17% [4/23]) vs 0% [0/51]; p < 0.01). CONCLUSIONS: The findings show that PTCSL is effective for treating primary hepatolithiasis, and that complete stone clearance is mandatory to diminish the sequelae of hepatolithiasis. Intrahepatic duct stricture was the main factor contributing to incomplete clearance and stone recurrence.

Management of pancreatic pseudocysts by endoscopic cystogastrostomy.

Open surgical drainage is currently the treatment of choice for pancreatic pseudocysts, but endoscopic transmural drainage is another minimally invasive surgical alternative. In this report, we describe two patients with symptomatic pancreatic pseudocysts treated with endoscopic cystogastrostomy. The first patient, a 15-year-old boy, had an episode of traumatic pancreatitis after abdominal injury from a car accident, and complained of postprandial vomiting and abdominal distention 4 weeks later. A large pancreatic pseudocyst, about 10 cm x 6 cm, was noted. The second patient, a 44-year-old man, had a 1-year history of recurrent alcoholic pancreatitis prior to this admission. He suffered from abdominal distention for several weeks. Sonography revealed a large pancreatic pseudocyst, about 18 cm x 9 cm in size. Both patients underwent successful endoscopic cyst-drainage without recurrence. These cases illustrate that endoscopic transmural drainage provides a minimally invasive and effective approach to the management of pancreatic pseudocysts.

Percutaneous cholangiofiberscopic endoluminal forceps biopsy of intrabile duct diseases.

BACKGROUND/AIMS: The aim of the present study was to determine the usefulness and sensitivity of percutaneous cholangiofiberscopic guided forceps biopsy in patients suspected of intrabile duct diseases. This study also emphasized the use of a video monitor system in which the field of view is magnified; thus, even a small lesion can easily be detected. Furthermore, coordination of both the operator and assistant is easier because both can observe the image together on the video monitor. METHODOLOGY: Percutaneous cholangio-fiberscopic forceps biopsy was performed in 27 patients (14 men, 13 women, aged 37-81 years with a mean age of 61 years). A mature T-tube tract was used as an access for cholangioscopy in 17 cases while the remaining 10 patients underwent percutaneous transhepatic biliary drainage and gradual tract dilatation from 7-French to 16-French. A flexible fiberoptic choledoscope was gently inserted into a mature tract and once an abnormal mucosal lesion was identified, a forceps biopsy was inserted into a working channel of the scope, and 3-5 specimens were taken for histological examination. RESULTS: A histological diagnosis was obtained in 24 cases of the 27 patients (sensitivity 89%) and included cholangiocarcinoma (n=8), papillomatosis (n=3), ampullary adenoma (n=1), ampullary adenocarcinoma (n=1), hepatoma with intrabile duct invasion (n=1), and chronic inflammation (n=10). Post-procedural bleeding was noted in 1 patient. CONCLUSIONS: Percutaneous cholangiofiberscopic-guided forceps biopsy is a safe and easy to perform procedure. It yielded a high sensitivity rate for definitive diagnosis of very small or early intrabile duct lesions; thus, a curative therapeutic modality can be appropriately applied. The use of a video monitor system, which magnified the field of view without distorting the quality of the image, plays a crucial role in this technique. Mucin substance is commonly seen in cholangiocarcinoma. The association between bile duct stones and neoplasm needs further evaluation.

Self-expandable metallic stents in the management of malignant biliary obstruction.

To overcome problems with conventional plastic endoprostheses, a study was conducted to determine the clinical efficacy of self-expandable metallic stents in the palliative treatment of malignant biliary obstruction. From May 1994 to March 1995, 19 self-expandable metallic stents were implanted in 13 consecutive patients with malignant obstructive jaundice due to cholangiocarcinoma (four patients), ampullary carcinoma (six), pancreatic carcinoma (one), and hepatic hilar lymph node metastasis (two). All patients underwent percutaneous transhepatic biliary drainage followed by stent insertion, except for two patients where the T-tube tract was used as access and another with previous placement of a polyethylene internal-external drainage catheter for more than 6 months. When both lobes of the biliary system were to be drained, stents were placed either side by side through punctured, separate hepatic ducts or, using a T configuration, through a single transhepatic tract. Percutaneous transhepatic stent placement was technically successful in all patients. After a mean follow-up of 5.9 months (range, 1-10 mo), 10 of 13 patients were still alive while three had died of nonprocedure-related causes. In 10 patients, total serum bilirubin levels decreased significantly (from 136.8 +/- 157 mumol/L to 34.2 +/- 22.2 mumol/L), while it increased in three patients. Two patients had stent occlusions at 2 and 3 months after stent placement, which required intervention. The overall patency period ranged from 1 to 9 months (mean, 5.1 mo). Our results confirm that the use of metallic stents is effective in the palliative treatment of malignant jaundice.

Percutaneous trans-hepatic cholangioscopy and lithotripsy in the treatment of intrahepatic stones: a study with 5 year follow-up.

BACKGROUND: Intrahepatic stones are characterized by high treatment failure and recurrence rates. In the past, surgery played a major role in the management of this disease, but surgical intervention may not be feasible in previously operated patients or those classified as poor surgical risks. The development of percutaneous trans-hepatic cholangioscopy and lithotripsy has played an important role in the treatment of these patients. METHODS: We reviewed our results in 165 patients with intrahepatic stones treated by percutaneous trans-hepatic cholangioscopy and lithotripsy in the past 12 years. RESULTS: The rate of complete stone removal was 80% (132 cases) and the rate of recurrent biliary stones after a mean 58 month follow-up interval was 32.6% (43 of 132 cases). There were 2 deaths during the treatment period and 10 deaths during follow-up. CONCLUSIONS: Percutaneous trans-hepatic cholangioscopy and lithotripsy are good alternatives in treating primary intrahepatic stones, especially for those patients unsuitable for surgery.

Bilateral hepatic duct decompression via a single percutaneous tract using a 'mother-baby' drainage catheter.

Decompression of the right and left hepatic ducts using a 'mother-baby' self-made drainage system via a single percutaneous tract was performed successfully in 15 of 21 patients with benign (n = 4) and malignant (= 17) hilar obstruction. The 'mother-baby' drainage system was composed of an 18 F catheter placed through the right hepatic duct into the distal common bile duct which was designated as the 'mother' catheter, while a second 10 F baby catheter was placed through the first catheter into the left hepatic ducts. This was achieved by a three-stage procedure: (1) percutaneous transhepatic biliary drainage; (2) balloon dilatation of the tract; and (3) intubation of the contralateral hepatic duct and placement of the 'mother-baby' drainage catheters. The mean interval of stent clogging was 5 months, with a range of 2-9 months. In 12 malignant cases, average survival time was 9.8 months. The technique avoided a second percutaneous hepatic puncture in centrally obstructing lesions and afforded bilateral biliary decompression.

Percutaneous choledochoscopic biliary tract stone removal: experience in 645 consecutive patients.

Our experience in non-operative retrieval of biliary tract stones through PTCS (percutaneous transhepatic cholangioscopy, n = 103) and POC (post-operative choledochoscopy, n = 542) plus the use of Dormia basket and EHL (electrohydraulic lithotripsy) is presented. The results of transhepatic and T-tube routes are compared, with emphasis on the technical difficulties encountered. The success rates were 96% and 97% in POC and PTCS, respectively. No mortality was related to these procedures. Intrahepatic duct angulation and stricture were the factors most often responsible for failure. Postoperative choledochoscopic stone removal is safe and the method of choice for retained biliary tract calculi, while PTCS is highly indicated for those high-risk patients with or without previous biliary surgery. POC and PTCS have, therefore, their own indications and differ in their clinical applications.

Endoscopic sphincterotomy in the treatment of biliary tract diseases.

Endoscopic sphincterotomy (EST) was performed in 53 patients with biliary disease. Indications for sphincterotomy were: 48 patients with choledocholithiasis, 3 patients with malignant biliary obstruction, and 2 patients with papillary stenosis. The procedure was successful in 52 patients (98.1%). In patients with choledocholithiasis, the stones were successfully removed or passed out spontaneously in 42 patients (87.5%). Endoscopic retrograde biliary drainage (ERBD) was successfully carried out in 2 cases of malignant biliary obstruction after EST. The clinical and biochemical evidence of cholestasis resolved in both patients with papillary stenosis. Complications consisted of hemorrhage (2 patients) and cholangitis (1 patient), resulting in one death. The overall complication and mortality rates were 5.7% and 1.9% respectively. Thirty-two patients received regular ultrasound examination follow-up with a mean of 13.4 months. Two patients had recurrent common bile duct stones and one had restenosis of papilla. The conditions were managed by endoscopic therapy. Endoscopic sphincterotomy is a relatively safe and effective means of relieving extrahepatic cholestasis; however, its comparison with surgical techniques needs long-term, randomized studies.

Transcholecystic endoscopic choledocholithotripsy: successful management of retained common bile duct stone.

Removal of large common bile duct stones has been a continuing challenge. The feasibility and efficacy of transcholecystic endoscopic choledocholithotripsy in a high-risk patient are demonstrated in this report. The procedure requires an established cholecystostomy track, catheter dilatation of the cystic duct, and the application of electrohydraulic shock waves to the calculus. The use of a choledochofiberscope permits the passage of the electrohydraulic probe and minimizes complications by direct monitoring. Stone fragments are removed by basket retrieval. This procedure in conjunction with minicholecystostomy may obviate the need for surgery in selected high-risk patients with combined gallbladder and common bile duct stones.