Francesco Maria Di Matteo

EUS-guided Nd:YAG laser ablation of normal pancreatic tissue: a pilot study in a pig model.

BACKGROUND Laser ablation with a neodymium:yttrium aluminum garnet (Nd:YAG) laser can achieve a high rate of complete tissue necrosis and has been applied as a minimally invasive, palliative option in hepatocellular carcinoma, liver metastasis in colorectal cancer, and malignant thyroid nodules. OBJECTIVE To assess the in vivo feasibility of EUS-guided laser ablation with an Nd:YAG laser of normal pancreatic tissue of a porcine model. DESIGN Prospective investigation. SETTING Hospital animal laboratory. SUBJECTS Eight pigs. INTERVENTIONS EUS-guided puncture of the pancreatic tail with a laser-beam fiber. An Nd:YAG laser (1.064 nm) was used, with an output power of 2 and 3 W and a total delivered energy of 500 and 1000 J in continuous mode. MAIN OUTCOME MEASUREMENTS The 24-hour follow-up of the pigs was focused on clinical and laboratory aspects. Results of histological studies of the pancreas were obtained 24 hours after the procedure on necroscopy tissue. RESULTS There were no technical limitations to the performance of the procedure. Tissue necrosis, localized in the pancreatic parenchyma, was observed in all animals on histological examination. The volume of ablation tissue ranged from a mean of 314 mm(3) to 483 mm(3). The ablation area ranged from a mean of 49 mm(2) to 80 mm(2). No major postprocedure complications were recorded, and all the pigs survived at 24 hours. LIMITATION Animal study. CONCLUSIONS EUS-guided laser ablation of the pancreas with an Nd:YAG laser is feasible in a porcine model.

Portosystemic shunts in a large cohort of patients with liver cirrhosis: detection rate and clinical relevance

BackgroundThis study aimed to determine the detection rate and clinical relevance of portosystemic collaterals.MethodsWe studied 326 cirrhotics. Portosystemic collaterals, portal vein diameter, and splenic area were evaluated by color Doppler sonography; esophageal varices were detected by endoscopy.ResultsOf the cirrhotics, 130 had portosystemic collaterals (39.9% total, left gastric vein 11%, paraumbilical vein 7.4%, splenorenal shunts 13.8%, and combined shunts 7.7%). Cirrhotics without portosystemic collaterals or with a paraumbilical vein had a significantly narrower portal vein diameter than cirrhotics with a left gastric vein (P < 0.001). Cirrhotics with a paraumbilical vein had a significantly smaller splenic area than cirrhotics with a left gastric vein (P < 0.001), splenorenal shunts (P < 0.001), combined shunts (P < 0.001), or without portosystemic collaterals (P < 0.05). A significant association between portosystemic collaterals and Child’s classes or presence and type of esophageal varices was found (P < 0.0001 and P = 0.0004, respectively). The highest prevalence of Child’s class C and large (F-3) esophageal varices was found in cirrhotics with a left gastric vein (41.7% and 36.1%, respectively), whereas esophageal varices were absent in 47.4% of cirrhotics without portosystemic collaterals and in 58.3% of cirrhotics with a paraumbilical vein.ConclusionsThe left gastric vein is associated with some sonographic and clinical markers of disease severity, whereas the absence of portosystemic collaterals or the presence of paraumbilical veins seems to identify cirrhotics with markers predictive of a more favorable clinical course.

EUS-guided Nd:YAG laser ablation of a hepatocellular carcinoma in the caudate lobe

Vascular liverinjuries and portobiliary fistulas related to biliary proceduresappear to be a more recognized complication of percutane-ous biliary drainage rather than ERCP. However, this casereport illustrates that if the apparent biliary anatomy looksunusual, particularly if radiographic contrast material washesout from the biliary tree, then entry into the portal vein haslikely occurred, a diagnosis of portobiliary fistula should beconsidered, and stent placement should take place only withcaution. As in this case, if a stent has been placed previously,then further stenting may be needed to occlude the fistula. Inthe occurrence of a portobiliary fistula, biliary stenting viaeither ERCP or percutaneous transhepatic cholangiographyoffers an opportunity to prevent significant hemorrhage andpotential portal sepsis.

US-guided application of Nd:YAG laser in porcine pancreatic tissue: an ex vivo study and numerical simulation

BACKGROUND Laser ablation (LA) with a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser is a minimally invasive approach able to achieve a high rate of complete tissue necrosis. In a previous study we described the feasibility of EUS-guided Nd:YAG pancreas LA performed in vivo in a porcine model. OBJECTIVE To establish the best laser setting of Nd:YAG lasers for pancreatic tissue ablation. A secondary aim was to investigate the prediction capability of a mathematical model on ablation volume. DESIGN Ex vivo animal study. SETTING Hospital animal laboratory. SUBJECTS Explanted pancreatic glands from 60 healthy farm pigs. INTERVENTION Laser output powers (OP) of 1.5, 3, 6, 10, 15, and 20 W were supplied. Ten trials for each OP were performed under US guidance on ex vivo healthy porcine pancreatic tissue. MAIN OUTCOME MEASUREMENTS Ablation volume (Va) and central carbonization volume (Vc) were measured on histologic specimens as the sum of the lesion areas multiplied by the thickness of each slide. The theoretical model of the laser-tissue interaction was based on the Pennes equation. RESULTS A circumscribed ablation zone was observed in all histologic specimens. Va values grow with the increase of the OP up to 10 W and reach a plateau between 10 and 20 W. The trend of Vc values rises constantly until 20 W. The theoretical model shows a good agreement with experimental Va and Vc for OP between 1.5 and 10 W. LIMITATIONS Ex vivo study. CONCLUSION Volumes recorded suggest that the best laser OP could be the lowest one to obtain similar Va with smaller Vc in order to avoid the risk of thermal injury to the surrounding tissue. The good agreement between the two models demonstrates the prediction capability of the theoretical model on laser-induced ablation volume in an ex vivo animal model and supports its potential use for estimating the ablation size at different laser OPs.

Invasive and non-invasive techniques for detecting portal hypertension and predicting variceal bleeding in cirrhosis: A review

Abstract Portal hypertension is a severe syndrome that may derive from pre-sinusoidal, sinusoidal, and post-sinusoidal causes. As a consequence, several complications (i.e. ascites, oesophageal varices) may develop. In sinusoidal portal hypertension, hepatic venous pressure gradient (HVPG) is a reliable method for defining the grade of portal pressure, establishing the effectiveness of the treatment, and predicting the occurrence of complications; however, some questions exist regarding its ability to discriminate bleeding from non-bleeding varices in cirrhotic patients. Other imaging techniques (transient elastography, endoscopy, endosonography, and duplex Doppler sonography) for assessing causes and complications of portal hypertensive syndrome are available and may be valuable for the management of these patients. In this review, we evaluate invasive and non-invasive techniques currently employed to obtain a clinical prediction of deadly complications, such as variceal bleeding in patients affected by sinusoidal portal hypertension, in order to create a diagnostic algorithm to manage them. Again, HVPG appears to be the reference standard to evaluate portal hypertension and monitor the response to treatment, but its ability to predict several complications and support management decisions might be further improved through the diagnostic combination with other imaging techniques.

Error of a Temperature Probe for Cancer Ablation Monitoring Caused by Respiratory Movements: Ex Vivo and In Vivo Analysis

Hyperthermal techniques are spreading as an alternative to conventional surgery for cancer removal. A real-time temperature feedback can be used to adjust the treatment settings, in order to improve the clinical outcomes. In this paper, we experimentally assessed the feasibility for distributed temperature monitoring of a custom probe, which consists of a needle embedding six fiber Bragg gratings (FBGs). Since FBGs are also sensitive to strain, we focused on the analysis of the measurement error (artifact) caused by respiratory movements. We assessed the artifact both on ex vivo pig liver and lung (by mimicking the movement of these organs caused by respiration) and on in vivo trial on pig liver. Lastly, we proposed an algorithm to detect and minimize the artifact during ex vivo liver laser ablation. During both ex vivo and in vivo trials, the probe insertion within the organ was easy and safe. The artifact was significant (up to 3 °C), but the correction algorithm allows minimizing the error. The main advantages of the proposed probe are: 1) spatially resolved temperature monitoring (in six points of the tissue by inserting a single needle) and 2) the needle is magnetic resonance (MR)-compatible, hence can be used during MR-guided procedure. Even if the model is close to humans, further trials are required to investigate the feasibility of the probe for clinical applications.

Endoscopic full-thickness resection of superficial colorectal neoplasms using a new over-the-scope clip system: A single-centre study

BACKGROUND AND AIM Endoscopic full-thickness resection (EFTR) provides complete en-bloc resection with a histopathological evaluation of submucosal, muscular, and serosal layers. The aim of this study was to investigate the efficacy and safety of a novel over-the-scope device for colorectal EFTR. MATERIAL AND METHODS In this retrospective, observational, open-label case study, a total of 20 patients with superficial colorectal neoplasms, underwent EFTR using a new endoscopic full-thickness resection device (FTRD; Ovesco Endoscopy, Tübingen, Germany). Endoscopic treatment outcomes (technical success, rate of EFTR, adverse events) and early follow-up at three months, were analyzed. RESULTS We reported a 100% of technical success, defined as full-thickness resection. Among the R1 resections, histology was negative for neoplasm. Non-lifting adenomas had histology positive for adenocarcinoma: seven T1/G1/sm1; one T1/G1/sm2; one, who underwent a surgical resection, T1/G1/sm3. Mean size of the resected lesions was 26mm, ranging from 10 to 42mm. One (5%) patient developed abdominal pain, fever and leukocytosis and was treated conservatively with medical therapy. In all specimens, histological complete resection was confirmed. CONCLUSIONS EFTR is a feasible and effective technique that could become a valid alternative to EMR and ESD in the management of recurrent adenomas, no-lifting lesions and scars of R1 resections. However, prospective studies are needed to further evaluate the device and technique.

Portal hypertensive gastropathy in cirrhotics without varices: a case-control study.

Objective Information is lacking on portal hypertensive gastropathy (PHG) in cirrhotics without varices; our aim it is to evaluate whether clinical and sonographic parameters are associated with PHG and may provide information suitable for the management of these patients. Patients and methods After endoscopic selection of 145 cirrhotics without varices, 75 with PHG and 70 without PHG, clinical and sonographic characteristics were assessed. Results Forty portosystemic shunts were present in 27 patients. The mean Child–Pugh score was 6.3±1.4 and 5.6±0.5 in patients with severe and mild PHG, respectively (P=0.004). The mean portal vein diameter was 10.4±1.7 and 11.6±2.0 mm in cirrhotics without and with PHG, respectively (P=0.0002). Conclusion A link between the presence of PHG and a more advanced phase of cirrhosis was found. Duplex Doppler sonography was confirmed to be a valuable diagnostic method in monitoring cirrhosis. Management of these patients cannot be performed on the basis of a single diagnostic method, and a multimodal diagnostic approach is required.

Pancreatitis after percutaneous ethanol injection into HCC: a minireview of the literature

Deaths after percutaneous ethanol injection (PEI) into hepatocellular carcinoma (HCC) may occur within a few hours to a few days following the procedure because of hemoperitoneum and haemorrhage from oesophageal varices or hepatic insufficiency. Pancreatitis has been recently reported as a rare lethal complication of intra-arterial PEI, another modality for treating HCCs. In this minireview, we analyze the literature concerning the development of acute pancreatitis after PEI. Pathogenesis of pancreatitis from opioids and ethanol is also addressed. Treatment with opioids to reduce the patients abdominal pain after PEI in combination with the PEI itself may lead to direct toxic effects, thus favouring the development of pancreatitis.

Feasibility assessment of an FBG-based probe for distributed temperature measurements during laser ablation

During thermal procedures, the monitoring of tissue temperature is useful to improve therapy success. The aim of this study is the feasibility assessment of a Fiber Bragg Grating (FBG)-based probe, which contains six FBGs, to obtain distributed temperature measurement in tissue undergoing laser ablation (LA). Among different thermometric techniques, FBG sensors show valuable characteristics, even though their sensitivity to strain entails measurement error for patient respiratory movement. We performed: i) the static calibration of the FBG-based probe to estimate the thermal sensitivity of the six FBGs; ii) the estimation of the response time of the FBGs. All FBGs have a thermal sensitivity of 10 pm·°C-1 and a time constant in the order of <; 250 ms. Additionally, we performed a preliminary estimation of the error due to the strain and caused by respiratory movements. Experiments were carried out by simulating a typical respiratory movement on ex vivo swine liver. The measurement error was <;0.6 °C for all FBGs. Eventually, experiments were performed on ex vivo porcine liver undergoing LA to assess the measurement error, called artifact, caused by the direct absorption of the laser light by the metallic needle. The artifact was firstly investigated at 12 relative positions between the needle and the laser applicator, then corrected by a two-variables model. After adjustment, the artifact decreases from about 2.1 °C to about 0.1 °C. The solutions proposed in this study foster confirming the feasibility of the FBG-based probe for temperature monitoring in organ undergoing LA.