PubMed Health⌕ Search

Biomedical subjects

T Mala

Publications and source records attributed to T Mala.

At least 19 recordsLinked to original sources
PubMed2006

Hepatic radiofrequency ablation using perfusion electrodes in a pig model: effect of the Pringle manoeuvre.

AIM: To assess the influence of the Pringle manoeuvre on volume and geometry of coagulations close to the portal vein using an impedance-controlled radiofrequency ablation system with perfusion electrodes. METHODS: Twelve pigs were randomly assigned to a control group (n = 6) and a group where the Pringle manoeuvre was applied during ablation (n = 6). One coagulation was made in each animal close to the portal vein. All animals were sacrificed 4 days after ablation, and the livers were removed for gross and histopathologic analysis. RESULTS: Effective coagulation volume in the Pringle group (10.8 +/- 5.0 cm(3)) was significantly increased (p = 0.03) compared to the control group (4.1 +/- 4.1 cm(3)). The efficacy ratio, defined as the effective coagulation volume divided by the coagulation volume, was not significantly different in the Pringle group (0.47 +/- 0.27) compared to the control group (0.33 +/- 0.22). The geometrical centre of the effective coagulation volume did not correspond to the position of the ablation electrode. Thermal damage of the gallbladder was found in three animals, all belonging to the Pringle group. CONCLUSIONS: The Pringle manoeuvre was associated with increased effective coagulation volume, but did not significantly influence the predictability of coagulation volume or geometry.

Animals↗
PubMed2005

Intra-operative visualisation of 3D temperature maps and 3D navigation during tissue cryoablation.

Thermotherapeutic tools are increasingly used for tissue ablation, although the intra-operative monitoring is not adequate for such procedures. This is a main challenge for more extensive use of any ablative technique. The present work focuses on treatment of hepatic tumours by cryo therapy. For any thermotherapeutic tool there are specific thermal conditions that have to be met to ensure treatment adequacy. A software tool was made to calculate and visualise 3D temperature distributions during hepatic cryoablation combined with a 3D intra-operative navigation system. This system aids the user in placing the cryoprobe using an optical tracking system and 3D visualisation of the probe placement in relation to the target anatomy and the planned trajectory. 3D temperature distributions are calculated and visualized intra-operatively. The system is integrated with an interventional Magnetic Resonance 0.5T scanner. The system was tested in an animal experiment, exemplifying the usefulness of the navigation system and its ability to give intuitive feedback to the user on thermodynamic conditions induced in the target region. The system constitutes a novel tool for enhanced intra-operative control during cryoablative procedures, and motivates for studies using this tool to investigate predictors applied as indicators of treatment adequacy and patient outcome.

Animals↗
PubMed2004

Laparoscopic resection of the pancreas: a feasibility study of the short-term outcome.

BACKGROUND: Laparoscopic resection is not an established treatment for tumors of the pancreas. We report our preliminary experience with this innovative approach to pancreatic disease. METHODS: Thirty two patients with pancreatic disease were included in the study on an intention-to-treat basis. The preoperative indications for surgery were as follows: neuroendocrine tumors ( n=13), unspecified tumors ( n=11), cysts ( n=2), idiopathic thrombocytopenic purpura with ectopic spleen ( n=2), annular pancreas ( n=1), trauma ( n=1), aneurysm of the splenic artery ( n=1), and adenocarcinoma ( n=1). RESULTS: Enucleations ( n=7) and distal pancreatectomy with ( n=12) and without splenectomy ( n=5) were performed. Three patients underwent laparoscopic exploration only. Four procedures (13%) were converted to an open technique. One resection was converted to a hand-assisted procedure. The mortality rate for patients undergoing laparoscopic resection was 8.3% (two of 24). Complications occurred after resection in nine of 24 procedures (38%). The median hospital stay was 5.5 days (range, 2-22). Postoperatively, opioid medication was given for a median of 2 days (range, 0-13). CONCLUSION: Resection of the pancreas can be performed safely via the laparoscopic approach with all the potential benefits to the patients of minimally invasive surgery.

Adenocarcinoma↗
PubMed2004

Cryoablation of colorectal liver metastases: minimally invasive tumour control.

BACKGROUND: Freezing is used for in situ destruction (ablation) of liver tumours not eligible for resection. The procedure is typically done during laparotomy. The objective of this report was to study tumour control at the site of freezing and a minimally invasive approach to cryoablation of colorectal liver metastases. METHODS: A prospective study of 19 patients was conducted between 1999 and 2003. Twenty-five tumours were ablated during 24 procedures (i.e. 5 reablations). Sixteen procedures were performed percutaneously, 5 during laparotomy and 3 laparoscopically. Magnetic resonance imaging (MRI) was used for intraprocedural monitoring during most procedures. Nine patients had concomitant liver resections performed (5 during laparoscopy, 4 during laparotomy). RESULTS: Out of 25 ablations, 18 (72%) were assumed adequate. Total ice-ball volume during percutaneous procedures was median 62 cm (range 32-114). Excellent imaging of the extent of freezing was achieved using MRI. Hospital stay for patients treated percutaneously was median 4 days (range 3-30). No perioperative mortality occurred. Tumour recurrence at the site of ablation occurred in 8 of 18 (44%) tumours adequately ablated. Actuarial 2-year tumour-free survival at site of ablation was 48%. At the time of analyses 12 out of 13 (92%) patients assumed to be adequately ablated were alive. Of all patients, 14 out of 19 (74%) survived. CONCLUSIONS: Short-term tumour control can be achieved following cryoablation of colorectal liver metastases. A minimally invasive approach is feasible but the diameter of metastases considered for percutaneous cryoablation should not exceed 3 cm.

Aged↗
PubMed2002

A comparative study of the short-term outcome following open and laparoscopic liver resection of colorectal metastases.

BACKGROUND: Laparoscopic resection of liver tumors is feasible, but few studies have compared short-term outcome of the laparoscopic approach to that of a conventional technique. METHODS: Eighteen tumor resections performed during 14 procedures (14 patients) by conventional surgery were compared to 21 similar resections performed laparoscopically during 15 procedures (13 patients). All patients had colorectal liver metastases. RESULTS: No perioperative mortality occurred. Surgical time, peroperative bleeding and blood transfusion requirement were similar in the two groups. The resection margin was involved by tumor tissue in one specimen laparoscopically resected and in two specimens conventionally resected (p = 0.58). Patients operated laparoscopically remained in hospital for median 4 days, while patients operated conventionally stayed median 8.5 days (p <0.001). Patients operated laparoscopically required less opioid medication than patients having conventional surgery (median 1 vs 5 days; p = 0.001). CONCLUSIONS: Short-term outcome of laparoscopic liver resection compares to that of conventional surgery, with the additional benefits derived from minimal invasive therapy.

Adult↗
PubMed2002

Local recurrence after mesorectal excision for rectal cancer.

AIMS: Controversy still exists about the optimal surgical treatment of rectal cancer. The main purpose of the present study was to compare local recurrence (LR) rates after mesorectal excision (ME) and conventional surgery (CS) technique. METHODS: All rectal cancer patients from a defined catchment area were included. Outcome after ME in the period 1993-1999 (n=161) was compared with the outcome after CS (n=217) in the period 1983-1992. Partial ME (PME) was the routine in upper, and total ME the routine in mid- and low rectal cancer. The follow-up programmes were identical, and the median observation times very similar (37 and 38 months) in the two periods. Five-year actuarial LR rate and survival were estimated using the Kaplan-Meier method, and adjustment for prognostic factors was performed with Cox regression analysis. RESULTS: Total LR rate after R0 resection was 7.7% crude and 9% 5 year actuarial in the ME period, as compared with 16.0% crude and 24% actuarial in the CS period (P=0.02). Cox regression analyses confirmed these differences with a hazard ratio of 0.40 for ME vs CS (P=0.02). Isolated LR rate was 2% after ME and 8% after CS. Five-year actuarial total LR rate after rectal resection with curative intent was 11% after ME and 27% after CS (P<0.01). Actuarial total LR rate after PME was 6%, and none of these patients developed isolated LR. CONCLUSION: Standardization of surgical technique and application of ME resulted in a significant reduction of LRs. LR rate was low after PME, indicating that this procedure is adequate in upper rectal cancer.

Adenocarcinoma↗
PubMed2001

[Surgical treatment of esophageal cancer].

BACKGROUND: Oesophageal cancer is a serious condition with low long-term survival. The objective of this study was to define procedural safety and survival following tumour resection. MATERIAL AND METHODS: All 46 patients (41 men) operated for oesophageal cancer at the National Hospital, Oslo, Norway between 1987 and 1994 were reviewed. Median age was 61 years. 23 patients had squamous epithelial carcinoma and 20 had adenocarcinoma. Right-sided thoracotomy combined with laparotomy was performed in 38 patients (83%). RESULTS: Serious complications occurred in 17 patients (37%). Seven patients developed postoperative anastomotic leakage. Eight patients were reoperated due to complications. Perioperative mortality was 13%. Surveillance time at the intensive care unit was median eight days; nine patients stayed at the intensive care unit for more than 20 days. Three and five year survival for patients with adenocarcinoma were 30% and 20% respectively, and for patients with squamous cell carcinoma 18% and 14%. INTERPRETATION: Surgical treatment of oesophageal cancer has high morbidity and mortality. Long-term survival is achieved in only few patients.

Adenocarcinoma↗
PubMed2001

[Liver resection--indications and results].

BACKGROUND: Liver resection is an established treatment for malignancies like colorectal metastases and hepatocellular carcinoma. MATERIAL AND METHODS: Indications and outcomes of liver resection at the National Hospital, Oslo, Norway was studied retrospectively in 226 patients operated between 1977 and 1999. RESULTS: The main indication for surgery was colorectal metastases (n = 137). The frequency of liver resection for colorectal malignancies was < 1 per 100,000 patients per year in the hospital's catchment area. Other indications included hepatocellular carcinoma (n = 30), benign tumours like hemangioma (n = 14), and various primary and secondary malignant tumours. Reoperation due to postoperative complications was performed in 13 patients (6%). Total perioperative mortality defined as death before hospital discharge or within 30 days after discharge, was 3% (7/226). No perioperative deaths occurred among the 159 patients operated after 1987. Five year survival for patients operated for colorectal metastases and hepatocellular carcinoma were 29% and 24%, respectively. INTERPRETATION: The main indication for liver resection is colorectal metastases. Liver resection is a safe operation with potential curation for selected patients.

Adolescent↗
PubMed2001

[Cryoablation--a treatment option for inoperable liver tumors?].

BACKGROUND: Most patients with primary and secondary liver tumours are inoperable by conventional surgery. This has prompted the development of different techniques of local destruction of liver tumours, i.e. cryosurgical ablation radiofrequency, laser, and microwave ablation. MATERIAL AND METHODS: On the basis of relevant literature and our own experience we describe the principles of local destruction by cryoablation of colorectal metastases. RESULTS: Indications for ablation are mainly colorectal metastases and hepatocellular carcinoma. Mechanisms for tumour destruction include intra- and extracellular ice crystal formation, cellular membrane rupture, cellular dehydration and ischaemic damage. Ablation is regularly monitored by ultrasonography, which is suboptimal because of inadequate visualisation of the iceball. Long-term outcome of local destruction of liver tumours is not documented and randomized trials are not ethically acceptable. This complicates analyses of patient outcomes. INTERPRETATION: Local ablation of liver tumours is experimental therapy and should only be performed as a part of prospective trials.

Carcinoma, Hepatocellular↗
PubMed2001

Laparoscopic and open surgery for pheochromocytoma.

BACKGROUND: Laparoscopic adrenalectomy is a promising alternative to open surgery although concerns exist in regard to laparoscopic treatment of pheocromocytoma. This report compares the outcome of laparoscopic and conventional (open) resection for pheocromocytoma particular in regard to intraoperative hemodynamic stability and postoperative patient comfort. METHODS: Seven patients laparoscopically treated (1997-2000) and nine patients treated by open resection (1990-1996) at the National Hospital (Rikshospitalet), Oslo. Peroperative hemodynamic stability including need of vasoactive drugs was studied. Postoperative analgesic medication, complications and hospital stay were recorded. RESULTS: No laparoscopic resections were converted to open procedure. Patients laparoscopically treated had fewer hypertensive episodes (median 1 vs. 2) and less need of vasoactive drugs peroperatively than patients conventionally operated. There was no difference in operative time between the two groups (median 110 min vs. 125 min for adrenal pheochromocytoma and 235 vs. 210 min for paraganglioma). Postoperative need of analgesic medication (1 vs. 9 patients) and hospital stay (median 3 vs. 6 days) were significantly reduced in patients laparoscopically operated compared to patients treated by the open technique. CONCLUSION: Surgery for pheochromocytoma can be performed laparoscopically with a safety comparable to open resection. However, improved hemodynamic stability peroperatively and less need of postoperative analgesics favour the laparoscopic approach. In experienced hands the laparoscopic technique is concluded to be the method of choice also for pheocromocytoma.

Adrenal Gland Neoplasms↗
PubMed2001

Magnetic resonance imaging-estimated three-dimensional temperature distribution in liver cryolesions: a study of cryolesion characteristics assumed necessary for tumor ablation.

The goal of this study was to estimate the three-dimensional (3D) temperature distribution in liver cryolesions and assess the margin of the transition zone between the tumoricidal core of the lesion and the surrounding unfrozen tissue, using criteria proposed in the literature. Local recurrences after liver tumor cryoablation are frequent. Temperatures below -40 degrees C and a 1-cm zone of normal tissue included in the cryolesion are considered necessary for adequate ablation. The 3D temperature distribution in 10 pig cryolesions was estimated by numerical solution of a simplified bioheat equation using magnetic resonance imaging data to establish cryolesion border conditions. Volumes encompassed by the -20, -40, and -60 degrees C isotherms were estimated. The shortest distance from every voxel on the -40 degrees C isotherm to the cryolesion edge was calculated and the mean and the maximal of these distances were defined for each cryolesion. Median cryolesion volumes with temperatures of -20, -40, and -60 degrees C or colder were 53, 26, and 14% of the total cryolesion volume, respectively. The median cryolesion volume was 12.3 cm(3). The median of the mean distances calculated between the -40 degrees C isotherm and the cryolesion edge was 4.1 mm and increased with increasing cryolesion volume. The median of the largest of these distances calculated for each cryolesion was 8.1 mm. Temperatures claimed to be adequate for tumor destruction were obtained only in parts of the cryolesion. The adequacy of a 1-cm zone of normal liver tissue included in the cryolesion to ensure tumor ablation is questioned.

Animals↗
PubMed2001

Validation of estimated 3D temperature maps during hepatic cryo surgery.

A simple model for estimating temperature distribution within the frozen region during cryo ablation was tested for accuracy. Freezing experiments were conducted in both ex vivo and in vivo porcine livers. Temperature was measured during freezing using a fiber-optic temperature sensor. Three-dimensional MR images were obtained at the end of each freezing cycle. From the MR image volumes, three-dimensional temperature maps were calculated numerically using a simplified bio-heat model. Estimated temperatures were compared to measured temperatures. The median difference between measured and estimated temperature was 3.03 degrees C. The median distance from a sensor element to the closest point on a isotherm surface with the corresponding estimated temperature was 0.70 mm. The accuracy of this model is acceptable. Temperature maps as outlined here may be used for monitoring of cryotherapy in order to increase clinical effectiveness.

Animals↗
PubMed2001

Magnetic-resonance-guided percutaneous cryoablation of hepatic tumours.

OBJECTIVE: To study the feasibility of percutaneous cryoablation of hepatic tumours monitored by magnetic resonance imaging (MRI). DESIGN: Prospective study SETTING: University hospital, Norway PATIENTS: Six patients with hepatic metastases from colorectal cancer. INTERVENTIONS: Percutaneous cryoprobe positioning under general anaesthesia. Positioning and freezing monitored by near-real-time MRI using an open 0.5 Tesla MRI configuration system. MAIN OUTCOME MEASURES: Safety and feasibility of the procedure. Measurement of volumes of cryolesions. RESULTS: One patient developed a biliary leakage that had to be drained. Four patients developed pleural fluid. Two small tumours were adequately cryoablated. In the remaining 4 patients with large (>4 cm) tumours, an adequate cryolesion could not be formed. Cryolesion volumes larger than 105 cm3 were not produced even using 3-4 probes. MRI visualised the growing cryolesion well, but positioning of the cryoprobes was time-consuming. CONCLUSION: MR guided cryoablation is clinically feasible and gives good visualisation of the procedure. Patients with small tumours (<3 cm) seem to be best suited to this percutaneous approach as cryolesion volumes claimed to be adequate for tumour destruction can be produced. Measurement of tumour volume preoperatively may help to select patients who will respond.

Aged↗
PubMed2001

Does tumor size influence the outcome of laparoscopic adrenalectomy?

BACKGROUND: Laparoscopic adrenalectomy is safe and effective for small adrenal tumors, but its role for large adrenal tumors and the influence of tumor size on the outcome of laparoscopic adrenalectomy have been questioned. PATIENTS AND METHODS: Thirty-one patients with unilateral adrenal tumors operated on between January 1997 and April 2000 were selected for this study. The indications for surgery were Conn's adenoma in 16 patients, pheochromocytoma in 7 patients, Cushing's adenoma in 4 patients, and incidental lesions in 4 patients. The patients were divided in two groups: 19 patients with tumors <3.5 cm (Group I) and 12 patients with tumors > or = 3.5 cm (Group II). The outcomes of the two groups were compared. RESULTS: None of the laparoscopic procedures was converted to open surgery. The tumor size correlated with operative time (r = 0.434; P = 0.015) and blood loss (r = 0.513; P = 0.003), with both being significantly greater for larger tumors. No patient required a blood transfusion during or after surgery. One preoperative complication occurred in Group I. There was no peroperative complication in Group II. The median postoperative hospital stay and opioid requirement did not differ significantly between the groups. One patient in Group I developed pneumonia, while no postoperative complications were recorded in Group II. CONCLUSION: Surgery for large adrenal tumors can safely be performed laparoscopically with outcomes comparable to those of surgery for small tumors.

Adrenalectomy↗
PubMed2001

Liver tumors and minimally invasive surgery: a feasibility study.

Laparoscopic liver resection has not yet been established, although recent reports document that liver resection can be performed safely by the laparoscopic approach. Other interventional procedures like cryoablation have also been introduced in treatment of liver metastases. In this report 11 liver resections performed laparoscopically in eight patients are presented. Six patients had colorectal metastases, one a metastases from a malignant melanoma, and one patient had focal nodular hyperplasia. Two patients received synchronous cryoablation of remaining liver metastases. During follow up, two patients received percutaneous cryoablation of liver recurrences monitored by an open configuration magnetic resonance scanner. All except one of the tumors we attempted to remove had free resection margins (re-resection of new metastasis). No complications occurred except an atelectasis of the left lower pulmonary lobe in one patient. Median postoperative hospital stay was 3 days, and median postoperative opioid-dependent days was 1. The report demonstrates that minimally invasive techniques may safely be combined in hepatic intervention, and that the advantages of minimally invasive surgery, such as reduced hospital stay and less patient discomfort, also applies to liver resections.

Adenocarcinoma↗
PubMed2000

[Endoscopic retrograde cholangiopancreatography--a 4-year retrospective study].

Endoscopic retrograde cholangiopancreatography (ERCP) may lead to serious complications. Recently, magnetic resonance cholangiopancreatography (MRCP) has been introduced as a diagnostic alternative to ERCP. This study was initiated to document the diagnostic and therapeutic capabilities of ERCP, enabling us to compare the two techniques. Results of 567 ERCP procedures in 371 patients were reviewed. Bile duct stones were the most frequent indication for the procedure (66%). Normal duct systems (37%) and common bile duct stones (35%) were the most frequent findings. Stone extraction was performed in 97 patients. In 18 patients minor stones were left behind and in six patients open choledocholithotomy was performed. Procedure related mortality was 0.3% and 0.8% in the diagnostic and therapeutic group respectively. Five patients developed serious pancreatitis, and duodenal perforation complicated two procedures. 56% of the procedures were diagnostic and could probably have been replaced by MRCP if this technique had been available during the study period.

Adult↗
PubMed1993

Physiologic adaptation changes of the "Bering Bridge" expedition participants.

Cardiorespiratory measurements were repeatedly performed on indigenous and Caucasian Soviet and American male team members of the Bering Bridge expedition which covered approximately 1280 km over a 61 day period. Significant baseline differences in cardiorespiratory functions at rest and during submaximal cycle ergometer exercise were noted between racial groups. Indigenous members had significantly lower mean vital lung capacity and oxygen consumption levels during submaximal exercise, but a greater systolic blood pressure response to exercise. The energy cost during submaximal work decreased during the trek in both groups, but was marked in the Caucasians, suggesting that the indigenous subjects were better adapted at baseline to the Arctic environment. Overall, there was stabilization of functional responses in four of seven parameters studied, although differences between racial groups remained the same.

Adaptation, Physiological↗